GAMMA SPECTROMETRY Included in the following pages are

o~..

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

.J /

RAD-GAMSpectrometryInstrument NotesSeptember 1979

9/79

E. INSTRuMENT NOTES: GAMMA SPECTROMETRY

Included in the following pages are Instrument Notes

for those instruments useful for gamma and x-ray spectrometry.

The reader should be aware of the following facts, in order

to find all Instrument Notes appropriate for gamma detectionand measurement:

1) The filing system lists Instrument Notes alphabetically

by manufacturer.

2) In the filing system, no distinction has been made

between gamma, gamma/x-ray, and x-ray instruments.The choice of mnemonic (GAM, GAM-XRA, or XRA) has

usually been made based upon the manufacturer's

advertised specifications.

3) Instruments for gamma and x-ray monitoring are

not included here. They have all been put together

in a separate section, after the text on "X and GammaRadiation Monitoring Instrumentation." Also, some

similar instruments, also sensitive to betas orto alphas and betas, have been placed in the beta

section (mnemonic RAD-BET, GAM) or under "Combination

Instruments" (mnemonic RAD-ALP, BET, GAM).

3.3.5-i

I

-~-INSTR.LDM6NTA{[aONU ,,)

FOR ENVIRONMENTAL

MONITORING

;)

Shielded Well Scintillation Counter

Baird Atomic Model 988-10C

RAD-GAM,BETLaboratoryBaird-AtomicMay 1977

9/79

Class

Principleof Operation

Sensitivity andRange

Sampling

Performance

Requirements

Features

References

Cost

Address

Laboratory

Well-type NaI (T1) scintillation detector system1-3/4" diameter x 2" thick NaI (Tl) crystal.Well size 21/32" ID x 1-35/64" Deep

Efficiency: 35% for Iodine-131Background: 250 cpm 20 cpm when used with spectrometer

Batch

Accuracy:Operating temperature: meets minimum requirements

Power: 110 Vac, 60 Hz (220 Vac, 50 Hz optimal)Size: 45.7cm H x 32.4cm diameter (18" height x 12-3/4" diameter)Weight: 131.5 kg (290 1bs.)

Lead shield, tube mount, Model 810LX does not include detector

Manufacturer's specifications

$1425.00

Baird-Atomic, Inc.125 Middlesex TurnpikeBedford, Mass. 01730(617) 276-6204

3.3.5.ba-1

I

-~-INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Ge(Li) Gamma Spectrometry Detectors

Canberra Industries

RAD-GAMSpectrometryCanberraJanuary 1978

Class

TRUE COAXIAL DETECTOR,

Laboratory

CLOSED-END COAX IAL DETECTOR

Principle ofOperation

Specifications

Features

References

Address

9/79

Ge(Li) semiconductor detectors used for gamma spectrometry.

Model 72lX Model 722

Shape Circular True Coaxial Closed End Coaxial

Active AreaUp to 20 Up to 28(cm2

)

Volume (ems) 10 to 100 10 to 150

Drifted DepthUp to 20 Up to 25(mm)

Resolution, FWHM 1.8 to 3 1.7 to 3(keV) for 1.33 MeV

Efficiency* Up to 20% Up to 30%

Peak-to-Compton Up to 40:1 Up to 50:1for 1.33 MeV

Price Range $9,282 - U7,589 $9,282 - $17,589

>IEfficiency measured relative to 3" x 3" NaI(Tl). at 1.33 MeV and

25" distance.

(1) Cryostats and associated electronics also available.(2) Model 1427 electronic unit available for fast-timing applications.

Manufacturer's Specifications

Canberra Industries45 Gracey AvenueMeriden, CT 06450(203) 238-2351

3.3.5.ca-l

! 1 J ;oJ) ~j 0"'~.J 'Oor ,.,/

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-GAMSpectrometryCanberra 2January 1978

Class


Specifications

NaI(Tl) Gamma Spectrometry Systems

Canberra Industries Model 802

Laboratory

NaI(Tl) crystal, photomultiplier tube, and tube base voltage divider assembledinto a unit for gamma spectrometry.

Crystal Crystal TubeDiameter Thickness Size Price for

Designation (em) (in.) (em) (in. ) (em) (in. ) Assembly

802-1 3.8 1-1/2 2.5 1 5.1 2 $247

802-3 5.1 2 5.1 2 7.6 3 $344

A802-3W 1. 59 .625 3.65 1.438 $381(well detector)

802-4 7.6 3 7.6 3 7.6 3 $420

B802-4W 1.67 .656 5.24 2.063 $1024(well detector)

Features

References

Address

9/79

(1) Entrance window 0.019" aluminum(2) Aluminum housing(3) Auxiliary electronics also available


Canberra Industries45 Gracey AvenueMeriden, CT 06450(203) 238- 2351

3.3.S.ca-3

t'i '

INSTRUME'~TA110NJFOR ENVIRONMENTAL

MONITORING

X-ray Detectors

Canberra Industries

RAD - GAM, XRASpectrometryCanberra 3January 1978

9/79

Class


Specifications

Features

References

Address

Laboratory

Si(Li) detectors used for x-ray spectroscopy

Model 7313 7333 7383

Area (mm2) 10 30 80

DepthCmm) 3 3 3

Resolution 1at 5.9 keY 160 eV to 170 eV 185 eVFWHM

Price Range2 $3,500 to $5,700

lGuaranteed worst case resolution @5,9 keY @iooo counts/sec. Typicalperformance exceeds specifications. 2) Includes Si(Li) detector, cryostatwith choice of 1.0, 0.5, 0.3 mil Be window, Model 1708 pulsed opticalfeedback preamp.

"Liquid nitrogen cryostat, preamplifier, spectrum enhancer, system alarm,LN mOhitor, and bias supply also available


Canberra Industries45 Gracey AvenueMeriden, CT 06450(203) 238-2351

3.3.5.ca-5

Oc

·'u/-- .. .. .

~ .J .. j ~': ~II\iSTRUMENT.A:TION'

FOR ENVIRONMENTAL

MONITORING

X-ray Scintillation Detectors

Canberra Industries

RAD-GAM ,XRASpectrometryCanberra 4January 1978

Principle· ofOperation

X-ray scintillation detector comprising a NaI(fl) crystal photomultipliertube and a voltage divider network

0.5 in. slit

Specifications Model 1701Window 0.005 in. Beryllium

Transmission 50% at 3.5 keY88% at 6.0 keY

Resolution 55% or better at 6 keYCollimator Removable brass with 0.125" x

Crystal NaI (Tl) 1" in dia., 1 rrnn thick

Photomultiplier Amperex XP 1010, selected

Cost$624

Model 1702

Type

Power

Output

with preamplifier

Charge sensitive, FET input

24 V

o to 20 V, 40 nsec risetime60 Ilsec fall time, 50 ohms inpedance

$980

References

Address

9/79


Canberra Industries45 Gracey Ave.Meriden, cr 06450(203) 238- 2351

3.3.5.ca-7

C)

//-,

(""--)

o

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

;l".j '<,.1 \J

Radioisotope Calibrator

RAn-GAMCalibratorCapintecJanuary 1978

9/79 3.3.5.cp-l

-~-INSTRUM ENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-GAMCalibratorCapintecPage 2

oClass


Laboratory calibration for gamma-emitting radioisotopes

Pressurized argon well-type ionization chamber and digital electrometersystem.

Each calibrates over 90 radionuclides. For CRe-20, computer memory canaccommodate up to 19 samples and concentration recall displays decay adjustedconcentrations for push-button isotopes with a ticket printed patient dosehard copy record.Accuracy: ~ 3% between calculated and observed values

---------.-------------~.....-----------


Function

Energy Range

SensitivityRange

Resolution

Dose Range

Performance

Requirements

Power:

Size:

Weight:

CRC-5/l0

Calibrator

To 6 Ci maximum

NA

Operating temperature:

CRC-5/l0

38.7 cm x16.5 emx 23.5 em15 1/4" Wx 6 1/2" Hx 9 1/4" D

18.1 kg (40 lb)

CRC-5M/IOM

Calibrator/radiationmonitor

25 keV to 3 MeV

To 6 Ci maximum (calibrator mode)

0.1 ]lCi

o to 200 mR/hro to 2 R/hro to 20 R/hr(Radiation monitoring mode)

CRC-5M/IOM

117 VAC~ 10%, 50/60 Hz

38.7 emx16.5 cmx 23.5 cm

15 1/4" Wx 6 1/2" Hx 9 1/4" D

20.4 kg (45 lb)

CRC-20

Calibrator

To 2 Ci maximum

NA

CRC-20

36.8 cmx 16.5 cmx 40.6 cm14 1/2" WX 6 1/2" Hx 16" D

23.6 kg (52 lb)

Features

Reference

1) Push button isotope selection2) Geometry independence3) 9%10 (interference w/ 99Tc) assay capability4) Accommodates small animals for total body assay5) CRC-5/l0 field upgradable to computer/printer model (CRC-20)

1) Suzuki, A., Suzuki, M.N., Weis, A.M., "Analysis of a RadioisotopeCalibrator," Journal of Nuclear Medicine Technology, Volume 4, pg.193-198, (December 1976).

2) Manufacturer's Specifications

Cost

Address

9/79

CRC-5/l0

$3250./$3700

Capintec, Inc.136 Summit AvenueMontvale, New Jersey(201) 391-3930

CRC-SM/IOM

$3970./$4225

07645

3.3.5.cp-2

CRC-20

$6300

o

INSTRUMENTATION

FOR ENViRONMENTAL

MONITORING

RAD-GAM,XRASpectrometryGEC-Elliott ProcessMarch 1978

Four Channel Gamma-Ray Spectrometer

GEC-Elliott Process Model Type 0928

Model Name and Nwnber

Class


Portable, designed for field use

Used with a variety of probes; it has a discriminator and three energychannels all of which may be preset within the range 50 keV to 3 MeV.Counts derived from ~-ray energies exceeding the discriminator thresholdor lying within the channel boundaries, may be displayed one at a timeon the front panel meter and, simultaneously, on an external 4-channelrecorder; alternatively they maybe displayed one at a time as anaccumulated count on a digital display.

cps

source

50 keV to 1 MeV1 MeV to 2 MeV1.25 MeV to 2.25 MeV2 MeV to 3 MeV

60 keV line from 24lAm referenceSpectrum stabilized usingcontained in probeFront panel switch allow test pulser of a 1Hz or 136 Hz to be injectedinto digital counting circuits so that the correct operation of eachcounting chain may be monitored.

1)

2)

Range (for channels 1,2, and 3): 0-10, 0-30, 0-100, 0-300, 0-1000Range (discriminator): 0-100, 0-300, 0-1000, 0-10,000 cpsSensitivity: depends on probeEnergy limits: DiscriminatorChannel 1 Channel 1Channel 2 Channel 2Channel 3 Channel 3

Sensitivityand Range

Features

References Manufacturer's specifications

Cost Refer to Manufacturer

Address GEC-Elliott Process Instruments LimitedNuclear Controls Division, Century WorksLewisham, SE13 7LN, England01-692 1271Telex 22469

9/79 3.3.5.ge-l

C)

o·

I

-~-INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

.'.

RAD- GAM,XRASurveyGEC-Elliott ProcessMarch 1978

Class

Gannna Survey Meter

GEC-Elliott Process Type 0593

Portable

9/79



Sampling

Perfonnance

Requirements

Features

References

Cost

Address

y-ray detector, solid-state circuitry, scaler, liquid crystal display, andaudible alann

Range: 0-5 digit readout

Continuous

Count cycling time: 2 secondsOperating temperature range: -5°C to 50°C

Power: Six "c" cellsSize: 7.4 cm x 12.4 ern x 24.0 cm (3 in. x 5 in~ x 9 1/2 in.)Weight: 1.6 kg (3.5 lb.)

1) Audible alann has an adjustable threshold and pitch related to countrate

2) Hermetically sealed3) Fully compensated to accommodate voltage changes between 9V and 6.6V4) Battery test switch


Refer to Manufacturer

GEC - Elliott Process Instruments LimitedCentury WorksLewisham, London SE13 7LN, EnglandTelephone: 01-692-1271

3.3.5.ge-3

u .) u UINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

;.JRAD-GAMSpectrometryHarshaw 3May 1977

Phoswich Scintillation Detector

Harshaw Chemical Company

---------- LOW BACKGROUNDOPTICAL WINDOW

LOW BACKGROUND

VOLTAGE DIVIDER BASE

LOW NOISEPHOTOMULTIPLIER

[CSI (TL)]SCINTILLATOR B

[NAI (TL)]

SCINTILLATOR A

LOW BAC KGROUND ------,

HOUSING [STAINLESS STEEL]

LaboratoryClass


Performance

The PHOSWICH detector is designed for high sensitivity radiation countingwhere low level, low energy radiation is normally obscured by backgroundradiation. The detector consists of a thin primary scintillator and athick secondary scintillator. Events that occur in the secondary crystalonly, and those events that occur in both crystals simultaneously, areelectronically rejected. Only the low level radiation that is totallyabsorbed by the primary scintillator is counted. Events are sorted outusing the Harshaw NC-25 Pulse Shape Analyzer which recognizes events in theprimary and secondary crystals by their different decay times.

By using a thin CaF2 (Eu) primary scintillator and a NaI(Tl) secondaryscintillator, the Phoswich can detect alpha and beta particles in thepresence of a gamma background.

Can suppress higher-energy backgrounds by factors of 3 to 10, compared toordinary NaI(Tl) or CsI(Tl) detector.

Especially designed for low-energy x-rays from Americium-24l, as used todetermine plutonium.

9/793.3.5.ha-l

Features

References

Pulse shape analysis system Model TASC-lO also available.o

RAD-GAMSpectrometryHarshaw 3Page 2 May 1977


Phoswich Detector-- _ $4500 - Depends on size

Harshaw Chemical Company6801 Cochran R-oadSolon, OH 44139(216) 248-7400

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING~rJ~-8

LI

Cost

Address

()

9/793.3.S.ha~2

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

X-ray Proportional Detectors

LND Models

RAD- GAM, XRASpectrometryLNDAugust 1977

9/79 3.3.5.ln-l

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD- GAM,XRASpectrometryLND 2Page 2 August 1977

Class Detector

X-ray Detectors

Maximum OverallDia. Length Operating

Model (em) (in. ) (em) (in.) Voltage Price Gas

456 2.54 1.00 10.16 4.00 1800 $300.00 Xenon4561 3.00 1.181 9.50 3.740 1850 $300.00 Xenon4562 2.54 1.00 7.62 3.00 1300 $300.00 Xenon4563 2.54 1.00 10.16 4.00 1400 $450.00 Neon4564 2.54 1.00 10.16 4.00 1400 $500.00 Neon4565 3.33 1.31 10.16 4.00 1200 $300.00 Xenon4566 2.54 1.0 13.97 5.5 1800 $350.00 Xenon4567 6.35 x 6.35 1.25 x 1.25 6.67 2.625 1850 $300.00 Xenon4568 4.20 x 4.20 1. 653 x 1. 653 14.47 5.697 1900 $450.00 Xenon

Reference Manufacturer's Specifications

Address LND3230 Lawson Blvd.Oceans ide, NY 11572(516) 678-6141

9/793.3.5.1n-2

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Ge(Li) Detectors

RAD- GAM, XRASpectrometersNuclear EnterprisesApril 1978

Class Laboratory

Nuclear Enterprises

9/79


Specifications

Features

References

Address

Ge(Li) semiconductor detector to be used with associated electronics,cryostat accessories

Series Designation

GDP GDC-T GDC-C

Planar Ge(Li) for TrapezoidalDetector Type or Cylindrical Coaxial Ge(Li)Low Energy X-Rays 5-Sided Ge (Li)

Area (rom) 4 to 15 10 to 40 4.5 to 15

Depletion Depth 5 to 15 5 to 15 8 to 15(rom)

Length (rom) - 10 to 78 23 to 78

Sensitive Volume 2 to 22.5 5 to 100 8 to 100(cm 3)

Energy Resolution 2.5 to 5 keV 2.5 to 5 keV 2.5 to 5 keVat 1.33 MeV

Peak/Compton 4:1 to 12:1 5:1 to 18:1 6:1 to 17:1at 1.33 MeV

Efficiency at1.33 MeV 1% to 11% 0.9% to 11%Compared to -

3" x 3" NaI(Tl)

Price Range $ to $ $ to .$ $ to $

Cryostats, associated electronics also available.3 grades of Ge(Li) available in each line.


Nuclear Enterprises, Inc.931 Terminal WaySan Carlos, CA 94070(415)592-8663. Telex: 348371

or

Nuclear Enterprises, Ltd.Bath Road, BeenhamReadingENGLAND

3.3.S.ne-1

u ") ,; ()INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

)

Si(Li) Detectors

Nuclear Enterprises

RAD- GAM, XRASpectrometryNuclear Enterprises 2April 1978

Class


Specifications

Features

References

Address

9/79

Laboratory

Si(Li) semiconductor detector to be used with associatedelectronics

Series Area Thickness Resolution at Price,Designation (rrnn) (rrnn) 6.4 keY, nOK Detector Only(FWHM, eV)

SDX 25-3A 25 3 280 $SDX 25-3 25 3 400SDX 50-3 50 3 450SDX 100-3 100 3 600

SDX 200-5 200 5 750

SDX 300-5 300 5 900

Si(Li) detectors available for particle detection also.Associated electronics also available.Cryostats available separately. 'Resolution measured at LN (77°K).


Nuclear Enterprises Inc.931 Terminal WaySan Carlos, CA 94070(415) 592-8663 Telex: 348371

or


3.3.5.ne-3

I-, f '~ . .;: . "1

INSTRUr¢lEN'TATf'0N ()

FOR ENVIRONMENTAL

MONITORING

NaI(Tl) Crystals

Nuclear Enterprises

RAD-GAMSpectrometersNuclear Enterprises 3May 1977

Class


Specifications

Laboratory

NaI(Tl) crystal coupled to photomultiplier tube

Crystal Sizes: Range from 1/2" x 1/2" to 6" x 4"Prices: Range from $ to $

De-mountable Assemblies:Prices: Range from $

Can accept crystal sizes from 1/2" x 1/2" to 6" x 4"to $

9/79

Other FeaturesAlso Available

References

Address

."..

Integral assemblies: Can accept cyrstal sizes with diameter up to andincluding 3",

Prices: Range from $ to $Special configurations manufactured to order,

Electronic accessoriesLow-background quartz windows &stainless steel mounts, Beryllium windowsAnti-Compton set-upsLarge well set-upsCesium-iodide (thallium) detectors also available


Nuclear Enterprises Inc,931 Terminal WaySan Carlos, CA 94070(415) 592-8663. Telex: 348371

or


3,3.5.ne-5

(\\, /

eJINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Si(Li) X-Ray Detector/Cryostat

Nuclear Semiconductor 101

RAD- GAM, XRASpectrometryNuclear SemiconductorJanuary 1978

Class


9/79

Nuclear Semiconductor 104

Laboratory (101) and portable (104)

Cryogenically cooled Si (Li) detector and pulsed optical feedbackpreamplifier. Vertical dipstick (17~) dewar

3.3.5.ns-l

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-XRASpectrometerNuclear SemiconductorPage 2 - o


Sampling

Perfonnance

Requirements

Features

References

Cost

Address

9/79

Range: Oxygen X = 8 to americium Z = 95Sensitivity: 1 ppm = 100% full scale

RESOLUTION AT 5.9 keV(FWHM in eV)

lOnnn2 3Onnn2 8Onnn2 20Onnn2 30Onnn2 Pricearea area area

144 148 165 $7280.148 155 170 6880.155 160 175 6080.165 170 185 4070.175 180 195 225 250 6490.

260 290 4490.

Continuous

Accuracy: ±O.l%Temperature Range: 10-35°CReadout Time: Instantaneous

Power: 110 V ac, 2 ASize: 91 em Hx48 em W (36" Hx17" W)Weight: About 45 kg (100 lb)

1) Detector mounted in shock absorber2) Other type dewars available3) Model 104-Portable spectrometer with 3 liter dewar, add $1500 to above

prices for the same perfonnance4) Electronic components available, also.


See table

Nuclear Semiconductor1400 Stierlin RoadP.O. Box 1389Mountain View, CA 94042(415) 969-9400

3.3.5.ns-2

C)

I

-~-I

LJ ..} s ) ,~.) ~,,)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

6

Survey Meter

RAD-GAMSurveyNuclear SystemsJune 1977

Gamma Industries Models lSOB, lSSB, 2S0B

Class Portable

Geiger-Muller tube as detector, amplifier, electrometer, meter readoutPrinciple ofOperation


Range:

Sampling

9/79

lSOB, lSSB

a - 2 mR/hra - 20 mR/hra - 200 mR/hr

Continuous

3.3.S.nu-l

2S0B

a - 10 mR/hra - 100 mR/hra - 1000 mR/hr

I INSTRUMENTATION

-'f:i2_ .. FOR ENVIRONMENTAL

l¥J MONITORING

Perfonnance

RAn-GAMSurveyNuclear SystemsPage 2 June 1977

150B - internal probe155B - external probeAccuracy:· ±. 20% PSOperating temperature range: -17.8C to 75QC (OQP to 167QP)

Time constants: -5 secEnergy range: 250 keV to 1. 5 MeV

C)

Requirements

Power:Size:

Weight:

150B, 155B

Two "D" Cells8.25 on x20.32 on X 10.16 on

(3 1/2" Wx 8" Lx 4" H)1.135.kg (2.5 1b)

250B

Two "D" Cells8.26 on x 20.32 onx 10.16 on

(31/4" Wx8" Lx4" H)1.25 kg (2.75 1b)

Features

References

1) Will not reverse in high intensity gannna radiation fields2) Low power consumption:> 400 hour,s from ordinary batteries, up to

1000 hrs on a1ka1ines.


Cost Model 150BModel 155BModel 250B

$275.00$325.00$250.00

Address

9/7'9

Nuclear Systems, Inc.924 Joplin St.P.O. Box 2543Baton Rouge, LA 70821(504) 387-0846TWX 510 993-3494

3.3.5.nu-2

INJ1RUMENrlATloiJ \}

FOR ENVIRONMENTAL

MONITORING

o t.JRAD-GAMSpectrometryOrtec 2May 1977

Ge(Li) Gamma Spectrometry Detectors, Systems

Ortec 8000 Series

~__-j_ 1-2.0 '

3.0

*2.75 for 25-mm-diam LEPS.

Vertical Dip Stick

*2.75 for 25-mm-diam LEPS.

Horizontal Dip Stick

9/79

Class


ENERGY.(keV)

124 ·62 n 21 16 12.4 10 6.2 3.1100

80~>u~U

~'"2i=2::>au 40

'"~ , IA):E 1~~~t1af-a~ 20

0.1 .2 .6

WAVE LENGTH (\)

Comparison of Ge(Li) LEPS and Si(Li) Detectors for High-Energy X-Ray Analysis.

Laboratory

Gennanium (Lithium-Drifted) detectors used for gamma spectrometry, andfull systems including dewar, preamplifier, cryostat.

3.3.5.or-1

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Specifications8000 Series Ge(Li) Coaxial Detectors

RAD-GAMSpectrometryOrtec 2Page 2 May 1977

()

ResolutionRelative FWHMb

Vertical Horizontal Photopeak (keV) for 60Co Peak-to-Detector Cryostat Cryostat Efficiency 1.332 MeV ComptonSeries M:>del No. Model No. (%) Ganrrnas Ratio Price

VIp10 Series 800l-l020V 8l0l-l020V ~ 10 ~ 2.0 ~ 33:1 $7,940Delivery: from

stock 800l-l022V 810l-l022V ~ 10 oS. 2.2 L 30:1 6,960

WIN15 Series 800l-l52lW 8l0l-l52lW L 15 ~ 2.1 ~ 36:1 10,490Delivery: from

stock 800l-l523W 8l0l-l523W ~ 15 ~ 2.3 L 33:1 9,770

TEC20 Series 800l-202lT 8l0l-202lT L 20 oS. 2.1 2- 41:1 13,090Delivery: fromstock to 60 days 800l-2023T 8l0l-2023T ~ 20 oS. 2.3 L 38:1 12,290

CUSTOM Single and multiple detector TO 75 To 1.7 200:1 PleaseSYSTEMS arrays available in a wide Cooled FET ask forDelivery: As range of cryostat, end cap, Systems factoryper quotation and dewar configurations Available quotation

~e ORTEC Ge(Li) Detectors are true_coaxial geometries to avoid the problems ot "Dead Layer" andpoor time resolution associated with closed-end type geometries.

bFWIM is ~ 2 x FWHM (Full Width at Tenth Maximum is ~ twice the Full Width at Half Maximum) •

Specifications for Cryostats and Dewars

lN2 lN2Typical Total

Cryostat Dewar Holding WeightM:>del Type Weight Volume Weight Weight Time Full ofNo. (kg) (liters) (kg) (kg) (days) lN2 (kg)

80 Vertical 2.45 31 24 15 28 41.5Dipstick

81 Horizontal 3.32 31 24 15 28 42.9Dipstick

/-,CJ

9/79 3.3.5.or-2

-~-I

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

·1J

RAD-GAMSpectrometryOrtec 2Page 3 May 1977

8000 Series Ge(Li) Low Energy Photon Spectrometers. aDelivery: stock to 30 days

Vertical Horizonts1 Diameter Drifted Depth Active Area Energy Resolution FWJ1MC (eV)Cryostat Cryostat

(mm) (mm) (mm2) At 5.9 keV (55Fe) At 122 keV (57Co)Model No. Model No.

8013-06180 8113-06180 6 5 30 180 4858013-06185 8113-06185 6 5 30 185 5008013-06200 8113-06200 6 5 30 200 5258013-10190 8113-10190 10 5 80 190 4908013-10210 8113-10210 10 5 80 210 5108013-10225 8113-10225 16 5 80 225 5258013-16260 8113-16260 16 5 200 260 5258013-16275 8113-16275 16 5 200 275 5358013-16300 8113-16300 16 5 200 300 5508013-25360d 8113-25360d 25 7 500 360 5958013-25380d 8113-25380~ 25 7 500 380 6158013-25400d 8113-25400 25 7 500 400 6158013-32500d 8113-32500d 32e 7 800 500 750

aA11 systems supplied with 5-mi1-thick Be windows and 31-1iter dewars except where noted.

bHorizonta1 common-vacuum configuration available special order.

'1Jsing optimum time constant of 2 to 6 l.lS FWI'M s. 2x FWHM. Total system resolution for 5.9 keV 55Fesource at 1000 counts/s measured in accordance with IEEE Standard 325 (1971), using ORTEC standardelectronics. Guaranteed for one year.

d10-mi1-thick Be window.

eSpecial order.

Features (1)(2)(3)(4)(5)

(6)

Detector efficiency is compared to that of 3" x 3" NaI (Tl) .Geometry is true cylindrical on all coaxial detectors.Electronic accessories (preamplifiers, etc) available.Spectrometer system has s. 1 \lill 'window'.End cap is 0.005" beryl1ium on all models except 0.010" on 25-mm-&32mm diameter models.Cryosorption pumping used in all spectrometers.

References

Address

9/79


ORTEC, Inc.100 Midland RoadOak Ridge, TN 37830(615) 482-4411

3.3.5.or-3

INSTRU:MENlf:iATldN \.4

FOR ENVIRONMENTAL

MONITORING

".J o

Si(Li) Photon Detectors

Ortec Series 7000

RAD-GAMSpectrometryOrtecMay 1977

l00I-TIIITlTIr-T'":::2~~"?"'I"TTr-~-rnTlnTl

80

~ 60~..5c2 40

j;;; .•~ 20

~

0.1

Class


Specifications

ElWIIlIV (keV)

Detectors

Silicon (Lithium-Drifted) Detectors for Low-Energy Photon Spectrometry

ORTEC Dewar Liquid Nitrogen Guaranteed Resolution* (eV)Cryostat Model Size Use Time FWHM for ~ Area/Diam. Range

Configuration No. (Liters) (Liters/Day) of12.5 nnn2

/ 30 nnn2/ 80 nnn2

/ 200 nnn2/ Price

4nnn 6nnn 10 nnn 16 nnn

Vertical 7013 30 1.1 205 215 230 325 $5,570.Dipstick 160 175 190 285 7,050.

Horizontal 7113 30 1.1 205 215 230 325 5,720.Dipstick 160 175 190 285 7,200.

Light Weight 7513 5 0.9 205 215 230 325 5,750.160 175 190 285 7,230.

Detectors are available with a guaranteed resolution better than that shown in table.*Total system resolution for 55Pe 5.9 keV at 1000 counts/sec measured with an ORTEC 7l6A,a 459, and a dc-coupled 5l2-channel analyzer. The FWI'M is ~ 2 FWHM. Guaranteed for oneyear. Upper value is standard. Lower value is premium.

Standard

Optional

9/79

Beryllium Entrance Windows

( 1 mil BeWinClow. Normally delivered with 4, 6, &\ 10 nnn diameter detectors., 2 mil Be Window, also.

jO. 5 mil Be Window. Thin, unsupported window for 4 and

6 nnn diameter detectors.

0.3 mil Be Window. Ultra-thin, unsupported window for4 nnn diameter detectors.

3.3.5.or-5

Price

Included in System Price

$220.00

330.00

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-GAMSpectrometryOrtecPage 2 May 1977

Features

References

Address

9/79

(1) Price includes: (a) Si(Li) crystal(b) Cryogenic Dynamic Charge Restoration Preamplifier(c) Cryostat with entrance window(d) Liquid nitrogen dewar

(2) Figure shows effect of different beryllium windows and Si(Li)thicknesses.


ORTEC, Inc.100 Midland RoadOak Ridge, TN 37830(615) 482-4411

3.3.5.or-6

INSTRUME~~ATi0N ~JFOR ENVIRONMENTAL

MONITORING

LJ

Na1 (Tl) Well-Type Spectrometers

Picker Nuclear

RAD-GAMSpectrometersPicker NuclearJune 1977

Cross Section view of the 621-940 Scintillation Well Detector.

Class

Principle· ofOperation

Specifications

Features

References

Address

9/79

Laboratory Spectrometers

Na1(Tl) well-type crystals with photomultiplier tubes and associatedelectronics, for gamma spectroscopy.

Na1(Tl) Crystal Size Sample Volumes Typicai 1251Model Number Accepted Background Price

Diameter Thickness (cc) Window 20-40 keV

621-940 2" 2" 15 70 CPM621-941 1. 75" 2" 5 55 CPM

Dimensions: 30.5 em x 33. 0 em x 41. 2 em(12" Wx 13" Dx 16 1/2" H)

Net Weight: 81 kg (180 lbs)

Auxiliary accessories also available.Shielding of at least 2" lead in all models.Other models, automatic systems also available.


Picker Corporation333 North State StreetNorth Haven, CT 06473(203) 484-2711

3.3.5.pi-l

()'-._-/"

; ~

~-.J ~.j (..J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

t) ./I

Isotope Calibrator

Picker MOdel 632-507

-

RAD-GAMSpectrometryPicker 2May 1977

9/79

Class



Performance

Requirements

Peatures

References

Cost

Address

Stationary, Laboratory

Pressurized, well-type, argon filled, ion chamber, electrometer, dosecomputing circuit, digital display, calibration

Energy Range: Gammas from 25 KeV to 3 MeVActivity Range: 1 \lCi to 999 mCi

Accuracy: < ±5% for any isotopeTemperature: 12°C to 45°CMeasurement Time: < 1 sec for samples above 200 \lCiRepeatability: ~ ±3% for 99m Tc above 100 \lCiStability: ~ ±l% drift for ±10% line voltage variation

Power: 115 Vac, ~10%, 60 Hz (optional 230 Vac, 50 Hz) 28 wattsSize: 30.4cm Hx 27. 9cm Wx43. 8cm D (12" x 11" x 17.3")Weight: 21.8 kg (48 lb)

Calibration factor feature allows selection of the followingradioisotopes and a variety of syringe and serum vial geometries.18p, 22Na, 24Na, 32p, 51Cr, 57CO, 60Co, 59pe, 67Ga, 68Ga, 75Se, 85Sr,

87mSr, 99V,o, 99IDrc 113mIn, 1251, 131 1, 133Xe, 137CS, 197Hg, 203Hg,

198Au, 226Ra


Picker Corporation333 State StreetNorth Haven, CN 06473(203) 484-2711

Picker Corporation~~rketing Services6119 Highland RoadCleveland, OHAttention: Mr. Prank Dean

3.3.5.pi-3

tj !.) \j tt";INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Spectrometer Components

Princeton Gamma Tech

RAD-GAMSpectrometryPrinceton Gamma-TechJanuary 1978

Class


Specifications


Ge(Li) and Intrinsic Germanium detectors, Amplifiers and other electronics,Cryostats and accessories

Ge (Li) Detectors

9/79

Range of Energy ResolutionEfficiency Peak/ComptonGeometry Relative to (keV) Ratio Price

3 x 3 NaI(Tl) at 1.33 MeVat 1. 33 MeV 1. 33 MeV 7.6 MeV

Modified Coaxial 5 to 26 1. 7 to 2.5 4.5 to 6.0 20 to 50 $5000 to $28,000

True Coaxial 5 to 16 1. 8 to 2.6 5.5 to 6.0 16 to 40 $6000 to $19,000

Standard Grade Coaxial Intrinsic Germanium Detectors,Straight Dipstick Cryostat, Pre-amplifier, l7-Liter Dewar

Area Resolution Resolution Be Window Price(mm2 ) at 5.9 keV at 122 keV Thickness-

25 155 eV 485 eV .0013" $6,300

25 145 480 .0013" 7,300

50 175 490 · 0013" 6,800

100 190 495 •0013" 7,900

200 240 540 •0023" 8,800300 300 570 .006"

,9,600I

400 350 610 · 006" 10,300

500 400 650 .006" 11,300

1000 600 800 I .006" 13,300_I

3.3.5.pr-l

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Semi~Planar Gc,Li) Detectors, SP-Series

RAD-GAMSpectrometryPrinceton Gamma-TechPage 2

()

Active Area Drift Energy Resolution PreampModel Depth Price(cm2 ) (mm) (eV, FWHM, at 122 KeY) Type

LGSPIOR 10 10 1000 RT $3,400LGSPIOC 10 10 750 CF 3,800

LGSP15,R 15 10 1050 RT 4,400LGSPISC 15 10 800 CF 4,800

Other sizes also available

Extra charges for other cryostats:Model ED, horizontal-looking dipstick $100.Model HT, horizontal-looking unitary (IS-liter) $250.Model DT, down-looking unitary (IS-liter) $250.

Features

References

Address

9/79

Many variations in full systems available.Special detector specifications available on request.


Princeton Gamma-TechBox 641Princeton, NJ 08540(609) 924-7310

3.3.S.pr-Z

(J

!. -I

\~) ~ .:!

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Ganuna Detectors

Quartz Products

RAD-GAMSpectrometryQuartz ProductsJtme 1977

FOUR SEGMENTWELL.TYPE SCINTIFLEX

305 VPFE 305

for pair spectrometry operable as ananti-Compton annulus by series

connexion of segments

Monocrystal NaI(TI): 21 305 mmh 305 mm

4 PhotomultipliersXP 1031 or RCA 8054Well: 0 elf, 83 mm,

o 60

o 66

.!" ~i_f==t=:t ('---;--l 1---i----.1(;j'''-''5'-t--1_---'---_

+I- -tf-_Aluminium

9/79

$~~~-----~=-I L_~i3__.._~-~.!~_~3-.!7

3.3.S-qu-1

Stainlesssteel tho 2

Alumina

Dimensions in mm

Class

INSTRUMENTATION

FOR ENV I RONM ENTAL

MONITORING

Laboratory

;'IWiGAM

'SpectrometryQuartz ProductsPage 2 June 1977

oPrincipleof Operation NaI(Tl) stintillators and photomultipliers

Sensitivityand Range Energy Range: 10 keV to 3 MeV, ganunas

12751

Performance

Requirements

Accuracy: About 9%Temperature: -50°C to 50°CCalibration: l37Cs resolution, 60Co peak-to-valley ratio, 55Fe for X-rays

Scintibloc Crystals (Solids &Well Types)Diameter rum: 32 38 44 51 76 76Height rum: 25 25 51 51 51 76Energy

Resolution: 7 - 9% for Cs-137 (661 keV)

Cost: $137.- $1194.

45 - 60% for Fe-55 (220 keV)$265. - $1194.

Scintibloc X CrystalsDiameter rum:Thickness rum:Energy

Resolution:

Cost:

25 32 441 to 5 1 to 5 1 to 5

76 to 2501 to 5 rum

203 228 292'102 102 102

7.5 - 9.5% for CS-137 (661 keV)

$1159. - $8500.Cost:

Scintibloc and Scintiflex Crystals (Solids and well-types)

Diameter rum: 102 102 127 127 127 152Height rum: 76 102 76 102 127 102Energy

ResolutioI' :

Note: Scintibloc refers to Direct CouplingScintiflex refers to Demountable Phototube

Features 1. Anti -Compton Annuli (Pair Spectrometer Annulus Option) from8" x 8" to 12" x 12"

2. Phoswich detector (NaI[Tl]/CsI[Tl]) for Plutonium studies3. Crystals up to 16" diameter

Other scintillating CsI (Tl) , CsI (Na) , Anthracene, Stilbene, ZnS (Ag)materials.

References Manufacturer's specifications

Address Quartz Products Corporation688 Somerset StreetP.O. Box 628Plainfield, NJ 07061(201) 757-4545

3.3.5.qu-2

9/79

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

".,) JRAD~GAM

LaboratorySearle AnalyticMay 1977

Class



Sampling

Performance

Requirements

Features

References

Cost

Address

9/79

Automatic Gannna COWlter

Seale Analytic Model 1185

Laboratory

A well~type scintillation detector and lead shield and a NaI(Tl) crystalwith nearly 4rr detection geometry

Sensitivity expressed in terms of E2/b ratio is at least 200 with a 2"crystalDynamic Range ~ 100:1

300 sample capacity, cOWlted individually

Typical efficiency is 80% with 25 CPM backgroWld when a 2" crystal is usedTemperature:

Power: l15V ± 10V, 60 HZ or 230 V 50 HZSize: 162.6 cm H x 111.8 em Wx 85.1 em D (64" H x 44" Wx 33.5" D)Weight: 907. 2 kg (2000 poWlds)

Automatic backgroWld subtraction, two or three analysis channels with bothpreset and adjustable windows, automatic calibration, automatic correctionfor spillover in dual labeled experiments, ratemeter. RIA data reductionavailable


Not known

Searle Analytic, Inc.2000 Nuclear DriveDes Plaines, IL 60018(312) 298-6600

3.3.5.se-l

; l;~~) ~.)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-GAM,XRASpectrometryTeledyne IsotopesJanuary 1978

NaI(Tl) Gamma Spectrometry Systems

Teledyne Isotopes

Radiation Entrance Window--

CanOillmeter

Can Length

Class


Specifications

9/79

Typiaal Assembly

Laboratory

NaI (Tl) crystals, photomultipliers, mOWlts, and assembled systems for photonspectrometry.

NaI(Tl) Crystals

(1) Wide variety of standard cylindrical crystals, from 1" (diam) x 1/2"(length) to 11-1/2" x 4".

(2) Well shapes and thin crystals also available.(3) Table shows a few representative crystals:(4) Response Time can be pre-determined to satisfy customer needs through

the use of specific Photomultiplier tubes.

Crystal CrystalDiameter Thickness Crystal

Designation (cm) (in.) (em) (in.) Price

S-42 2.54 1" 1. 27 1/2"S-44 2.54 1" 2.54 1"S-64 3.81 1-1/2" 2.54 1"S-88 5.1 2" 5.1 2"S-12l2 7.6 3" 7.6 3"S-16l6 10.2 4" 10.2 4"S-2020 12.7 5" 12.7 5"S-32l6 20.3 8" 10.2 4"S-46l6 29.2 11-1/2" LO.2 4"

ST-41 2.52 1" lmmST-46 2.54 1" 6mmST-8l 5.1 2" lmmST-86 5.1 2" 6mm

3.3.5.ti-l

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-GAM,XRASpectrometryTeledyne IsotopesPage 2

AssembliesSpecifications(Continued) (1)

(2)

(3)(4)(5)

(6)

(7)

Many types of assemblies available.All "Integral Series" assemblies have photomultiplier attached toNaI(T1), all hermetically sealed.Magnetic shield included.Tube base available as extra option.A1wnimnn housing (0.020") standard: copper or stainless steel alsoavailable.Phototubes used are DuMont 3240 and 3248L, RCA 6342AV1,2060, EMI 9778,9578B and 4524.Well-type and other geometries also available.

Designation

S-64-IS-78-IS-84-IS-88-IS-1208-IS-1212-I

CrystalDiameter

1-1/2"1-3/4"

2"2"3"3"

CrystalThickness

1"2"1"2"2"3"

Price

References

Address

9/79


Teledyne Isotopes50 Van Buren AvenueWestwood, NJ 07675(201) 664-7070

3.3.5.ti-2

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

NaI (Tl) Spectrometer Systems

Tennelec, Inc.

RAD-GAMSpectrometryTennelecFebruary 1978

Class


Specifications


NaI (Tl) crystal, photoll1Ultiplier tube for gamma spectroscopy.

Crystal Size

Diameter Thickness Model TypePerformance

Data Photomultiplier Tube Price

Thin Window NaI(Tl) X-Ray Detectors(55Fe Peak/Valley Ratio, 5.9 keV)

25mm xL 5mm (1" x 0.2") TD 25 SX 1/532mm xL 5mm (1. 25" x 0.2") ,TD 32 SX 1/544mm x 1. 5mm (1. 75" x 0.2") TD 44 SX 1/5

15:115:115:1

Philips XPlOlOPhilips XPlOlOPhilips 153 AVP 02

$ 430$ 500$ 600

Standard NaI (Tl) Assemblies(137Cs Energy Resolution, 662 keV)

25mm x 25nrrn (1" xl") TD 25 S 25 8.5% RCA 6199 $ 14032mm x 25mm (1. 25" xl") TD 32 S 25 8.5% RCA 6199 $ 15038mm x 25mm (1. 5" xl") TD 38 S 25 8.5% RCA 6342A $ 16544mm x 5lmm (1. 75" x 2") TD 44 S 51 8.5% RCA 6342A $ 2705lmm x 5lmm (2" x 2") TD 51 S 51 8.5% RCA 6342A $ 32076mm x 5lmm (3" x 2") TD 76 S 51 8.5% RCA 8054 $ 70076mm x 76mm (3" x 3") ill 76 S 76 8.5% RCA 8054 $ 850

102mm x102mm (4" x 4") TD 102 SE 102 9.0% RCA 8055 $1,490l27mm x l27mm (5" x 5") ill 127 SE 127 10.0% RCA 8055 $2,290

Well Type Assemblies(137CS Energy Resolution, 662 keV)

44mm x 5lmm (1. 75" x 2")5lmm x 5lmm (2" x 2")76mm x76nnn (3" x3")102mm xl02mm (4" x 4")l27mm x l27mm (5" x 5")

ill 44-SP-5lTD 5l-SP-5lTD 76-SP-76ill 102-SPE-l02ill l27-SPE-127

9.0%9.0%9.0%

10.0%11.0%

RCA 6342ARCA 6342ARCA 8054RCA 8055RCA 8055

$ 330$ 390$ 990$1,645$2,645

9/79

Features

References

Address

Electronic accessories also available. Individual NaI(Tl) crystals alsoavailable. All assemblies have magnetic shielding, hermetic seals.


Tennelec, Inc.P.O. Box DOak Ridge, TN 37830(615) 483-8405

3.3.5.tn-l

· ,",...~

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

.)

NEUTRON MONITORING INSTRUMENTATION

RAD-NEUPage 1

~-

1. Introduction

2. Radiation Protection Considerations

3. Measurement Considerations

A. Thermal Neutrons

B. Intermediate-Energy Neutrons

C. Fast Neutrons

D. Relativistic Neutrons

E. Dose-Equivalent Instruments

4. Sources for Calibration of Neutron Instruments

5. Summary and Recommendations

6. Acknowledgement

7. References

8. Instrument Notes

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 3

1. INrRODUCTION

There are a large number arid varietyof applications where a significant amountof radiation is due to the presence ofneutrons. Among these are:

a. charged particle accelerators,particularly proton and ionaccelerators and high-energyaccelerators;

b. nuclear reactors;

c. sealed neutron sources.

These sources vary widely in the intensities, energy spectra, and temporal durations of the neutron f1uences involved.From the highest-energy proton accelerators,primary beam interactions can produceneutrons with energies up to the full energyof the primary protons themselves, while inreactor situations there can be a heavyweighting toward thermal neutrons. Giventhis wide energy range, it is remarkablethat one can give any unified treatment tothe general problems of measurement ofneutron fluences. However, a unificationis indeed possible, for a large class ofapplications, primarily because of thecharacteristics of neutron interactions inshielding materials.

Neutrons traversing through materialcan interact in one of five general ways:

a. elastic scattering from nuclei;

b. inelastic scattering through nuc1earlevel excitation;

processes in degrading neutron energies inshielding (hence, the common use of concrete). Also, at energies much higher thanthose of typical nuclear levels (a few tensof MeV, say) a major energy loss mechanismis nuclear break-up or (above a few hundredMeV) mu1tipartic1e interactions, such aspion production. These facts have longbeen well known, and have influenced shielding design around major sources of neutronsand other particles. The unification oftreatment mentioned above is primarily dueto the effectiveness of energy-degradationprocesses in appropriately designed shielding, such that even at the highest energyaccelerators the major components of neutronf1uence are almost never at energies abovea few tens of MeV.

Neutron interactions, then, generallytend to degrade energies continually, downto the region where the neutrons can beabsorbed and eliminated by nuclear reactions.The ultimate energy degradation is neutron'therma1ization'; thermal neutrons are thosewith an energy spectrum in thermal equilibrium with the ambient material. Thermalneutrons can scatter without energy lossin, for example, air or concrete for relatively indefinite periods; while therma1ization of a several-MeV neutron can takefrom a few to a few hundred microseconds,thermal-neutron lifetimes themselves canbe as long as a few tens of milliseconds,until they are ultimately eliminated bynuclear absorption or reactions such as the(n,a.) mentioned above.

Historically, it has been common todivide the neutron energy spectrum into thefollowing approximate categories:

Intermediate energy 0.5 eV to 200 keVneutrons

This division is convenient both because of the different types of processeswhich are typical of these energy regions,and because instrumentation is often senSitive in only one of the categories. We shalldiscuss instrumentation partially accordingto these divisions, noting that in manyapplications one has a priori knOWledge

200 keV to 20 MeV

c. quasi-two-body interactions suchas (n,a.) or (n,np) interactions;

d. nuclear excitation or catastrophicbreak-up;

e. the high-energy phenomena of manyparticle production.

The relative importance of each of thefive general types depends on both neutronenergy and target material. Thus, elasticscattering from heavy nuclei is a veryinefficient energy loss mechanism, as iseasily seen from kinematical considerations.However, elastic scattering from hydrogennuclei (protons) is one of the most useful

Thermal neutrons

Fast neutrons

Relativistic neutrons

o to 0.5 eV

>20 MeV

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 4

that the neutron energy extends up to only aparticular energy region.

For detailed information about techniques of neutron dosimetry, the reader isreferred to several excellent papers andconference proceedings. (Ref. 1,2,3,4,5,6)

2. RADIATION PROTECTION CONSIDERATIONS

In the general case of occupationalexposure to external radiation, the relevantMaximum Permissible Exposure guideline(discussed in more detail in the introductorypart of this volume) is a basic limit todose-equivalent of 5 rem/year, with no morethan 3 rem to be accumulated in any l3-weekquarter and no lifetime accumulation up toage N years in excess of 5 (N-lS) rem.

The complication in measuring neutronrem (absorbed-dose equivalent) is thevariation of quality factor (QF) withenergy. Figure 1 shows the ICRP reconnnendedQF for neutrons as a function of energy.Figure 2 gives the flux density of primaryneutrons, in equilibrium with their secondaries, which is reconnnended by ICRP asbeing equivalent to 2.5 mrem/hour (Ref. 7).The inverse curve (Figure 3) is the energyresponse required of a neutron detectorsuch that different energies are weightedproperly for a direct determination of doseequivalent (rem).

3. MEASUREMENT CONSIDERATIONS

There are three main tasks in neutronmonitoring:

1. Measurement of the intensityspectrum as a funct!on ofenerR' (neutrons cm 2 MeV-Isec ).

2. Measurement of the total absorbeddose equivalent (rem or rem/sec).

3. Determination of the level ofother possible particle species,and the response of neutroninstrumentation to them.

There does not exist a single instrument or instrument type which can performcompletely all of these functions (or indeed,anyone of them separately). However, theredoes exist instrumentation more or less

adequate to the needs of the health physicist responsible for radiation protectionaround any of the sources mentioned above.The wide range of energies and fluencespreviously mentioned must be considered,along with several other concepts such astissue-equivalence and particle equilibrium,which have been treated in the introductorysection of this volume.

A. Thermal Neutron Measurements(below 0.5 eV)

Truly thermal neutrons, which havean energy spectrum in thermal equilibrium with the ambient environment,are centered at an energy of about0.025 eV. However, in actual practice,very few situations exist in which theneutron fluence is solely thermal:one possible case is that in whichneutrons are almost totally thermalizedfor some application such as a thermalcolumn. Many detection systems forhigher-energy neutrons depend uponthe process of (partial or complete)thermalization, with subsequent detection of the thermal neutrons usingone of the techniques to be discussedin this section.

There is usually both a trulythermal (Maxwellian) component and acomponent with a continuous energyspectrum above thermal, typicallywith a ("epi -Maxwellian") distributioninversely proportional to energy.Also, most of the reactions used todetermine thermal neutron flux densities have cross-sections which are almostexactly proportional to l/velocity inthe range from thermal up to thecadmium cut -off energy. (Since a cadmiumabsorber prevents neutrons below about0.5 eV from reaching a detector, itallows a convenient separation atabout that energy.) Because fluxdensity (neutrons cm- 2 sec-I) is proportional to velocity (if they aregoing twice as fast, they cross anyarea in half the time), the reactionrate per atom for a pure l/v detectoris independent of velocity and proportional only to the total neutrondensity. Table 1 (from Ref. 5) shows mostof the connnon thermal neutron reactions;the coefficient g(20oC) in the righthand column indicates the departurefrom l/v dependence for each reaction.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 5

II

10

9

8~U 7.2,.. 6~

g 5

o 4 Thermal(0.025 eV)

:3 !2

neutrons, as recommendedFIGURE 1:

O'~,-m<r-.'rr-...L--,x..-rI<><-,'--;),1-"I,,...--'----,10,..--n9.-...L--"l,1

o.ooei leV lkeV I MeV IGeVEnergy (electron valls)

(

QUALITY FACTOR vs. ENERGY for monoenergeticin ICRU Report No. 20.

10 100 ,A 100 ,A 100 10leV IkeV I MeV IGeV

Energy (electron volts)

rThermal(0.025 eV)

I 0.01 0.1O.OOleV

~..Do

7~s:e~

.§

~ 100

'lie 10~)(:0

r;::c:E:0..Z

FIGURE 2: MONOENERGETIC NEUTRON FLUX vs. ENERGY which yields MADE of 1 mrem/hour.

Thermol{0.025 eV}

+

161~, 0.01 0., 10 100 ,A 100 ,aQOOleV leV !keV I MeV

Energy (electron valls)

100IGeV

FIGURE 3: NEUTRON DOSE (rem) vs. ENERGY for 1 neutron/cm2 (for monoenergeticneutrons incident normally on a 30 em-thick tissue-equivalent phantom:ICRU Report No. 20).

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Table 1

Useful Thermal Neutron Detectors

RAD-NEUPage 6

Nuclide or Reaction Half-Life of <TO X 1024 forElement Nuclide Produced Production

cm2g(20·C)

sHe (n,p)3H 12.3 y 5327 1.06Li (n, t)4He stable 945 1.0lOB (n,a)7Li stable 3837 1.02sNa(I8) (n,'Y)24Na 15.0 h 0.534 1.0458c(I8) (n,'Y)468c 85d 22.3BV (n,'Y) 52V 3.8 min 4.9 1.055Mn(I8) (n,'Y)56Mn 2.58h 13.3 1.059Co(18) (n,'Y)60Co 5.24y 36.6 1.06SCU (n,'Y) 64CU 12.8h 4.5 1.0mIn (n,'Y)l161nm 54 min 157 1.019l57Gd (n,'Y)158Gd stable 242000 0.854197Au(18) (n,'Y)198Au 2.70d 98.8 1.0052S5U fission many 577 0.976

Notes: (18) denotes natural monoisotopic element.

For a more detailed discussion ofthermal neutron spectra, departuresfrom Maxwellian distributions, andneutron temperature the reader isreferred to ICRU Report No. 13 (Ref. 5) .

The most corrnnonly used thermalneutron detector is the BF3 filled gasproportional counter, wlu"Ch is corrnnercially available in a wide variety ofsizes and sensitivities. The reactionemployed is lOB(n,a) 7Li, in which thealphas are detected. The Q (kineticenergy released) is 2.8 MeV, but mostof the capture goes throu~ an intermediate excited state of Li, whichthen decays to the ground state byemission of a 470 keV garrana. In mostcounters the BF 3 gas ·is enriched withboron-IO to about 96%. (Naturalabundance is 20% lOB and 80% IlB). Thecross-section of the above reaction isabout 3800 barns with a l/v dependencein the thermal-energy range. Thus BF3counters are relatively insensitive toparticles with energies significantlyabove that of thermal neutrons(0.025 eV). The sensitivity dependson counter size, gas pressure, andenrichment. The response to garranafields is very low. In fields of equalgarrnna and neutron fluxes, the garrana

response is typically two orders of magnitude smaller than the neutron response(Ref.1) . An exception is when the BF 3detector is inside a moderator, andpulsed fields are being detected (suchas near a low duty-cycle accelerator).In that case, photons can pile up andcount.

The 3He gas proportional counter isanother corrnnonly used detector, similarto the BF3 counter. It relies uponthe reaction 3He (n,p) 3H, with a Qvalueof 765 keV. Both the proton and thetriton (3H) are available for ionization, but one of the problems is thatnear the walls efficiency can suffer,due to the rather low stopping powerof the 3He gas. This deficiency canbe overcome either by increasing thevolume or gas pressure, or (m0recommonly) by adding an impurity (usuallyargon or krypton) to improve the stopping power. The disadvantage of theimpurity is that garrana sensitivity isincreased, while pulse rise-time isdecreased. Because of the small Qvalue, garrnna sensitivity is greaterthan in the BF~:filled counter, butneutron sensitlvity is also greater(Ref.l), until the recoil particlesbecome too long (at neutron energiesabove about 10 MeV).

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

For neutron detection in highproton fields, lOB-lined proportionalcounters are used. The react10n 1Sthe same as for BF 3counters, exceptthat the lOB is coated on the counterwalls, in thicknesses that range fromabout 0.2 to 1.0 mg/cm2• Sensitivityis proportional to coating thickness,but self-absorption of the alphas prevents significant increases in sensitivity at greater thicknesses. Thesecounters are extremely insensitive tophotons, and are capable of neutronsensitive operation in photon fieldsas high as 104 or even 105 R/hr.However, their sensitivity to neutronsis perhaps an order of magnitudesmaller than that of the BF3 counter(Ref. 1). A typical fill gas is C02or Argon. The operating voltage isusually lower than that of the BF3 or3He tubes, and typically larger outputpulses with shorter rise times areproduced.

Still another gas proportionalneutron detector is the fission counter.A material such as 233U, ?03S U, or 239 puis coated on the walls. The kineticenergy of the fission fragments (approximately 200 MeV) produces large pulsesand fast response time. The sensitivityof these counters is inherently lowerby perhaps an order of magnitude thanthe lOB lined counters, and two ordersof magnitude below that of the BF 3tubes (Ref. 1). However, operation attemperatures as high as 7009C and inextremely high gamma fluxes (up to106 R/hr) makes them attractive forapplications such as inside reactorshielding. It should be noted herethat special licensing is'often required to obtain the fissionablematerial within the counter.

Ionization chambers are also usedfor thermal neutron detection. BothlOB-lined and BF3-filled ion chambersare used. Many of the same characteristics apply which have already beendiscussed in the case of the gasproportional counters. The ion chambersare generally less sensitive than thegas proportional counters (Ref. 1).A fuller treatment of ionization chambers can be found below.

RAD-NEUPage 7

Scintillation counters (in whichphotomult1pl1er tubes detect the lightproduced by ionization in scintillator)are also used for detection of thermalneutrons (Ref. 1). Among the. most sensitive are a lithium-iodide crystal witheuropium activation [6LiI(Eu)J ; 6Liloaded, cerium-activated silicate glass;and 6Li-loaded, zinc-sulfide crystals.In each case one counts the alpha andtriton from the reaction 6Li (n,a) 3H,with a Qof 4.8 MeV. If the detectoris large in size there can be a significant perturbation of the fieldbeing measured. However, the gammarejection is excellent, with gammasensitivities typically one to twoorders-of-magnitude below those forneutrons. The crystal itself (andthe others as well) have negligibleanisotropy of sensitivity, except forself-shielding and the flux perturbations already mentioned. A description of some of the properties of .cerium-activated glass has been givenby Ginther (Ref. 8); and a discussion of6Li-loaded glasses is given by Bormannet al (Ref. 9).

Another technique is the activationof a NaI (rl) crystal, in which onecounts the decay after activation of24Na (IS hour half-life, S withE...~ =2.12 MeV). An advantage of thist~~finique is the good detection efficiency for the decay betas. The sensitivity is very low, perhaps 104 belowthat of the others previously mentioned.Although common at one time, this technique is not often used today. Smallcrystals (say, 1 mm thick) must be usedto minimize the problem of perturbationof the incident flux. For a good description of the NaI method, the readeris referred to Grimeland (Ref. 10).

Zinc sulfide glass with lOB loadingis another mater1al used as a scintillator; however, it suffers from twoproblems (Ref. 1) when compared to itscounterpart, 6Li-loaded ZnS: first,poorer gamma discrimination, becauseof the lower Qvalue of the (n,a) reaction; and second, typical sensitivities several orders of magnitude lowerthan for the lithium-loaded crystals.Thus, only in situations where neutronfluences are high and photon levels areknown to be small can the lOB-loadedZnS be useful.

$I

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RAD-NEUPage 8

the flux in the region near 1.5 eV,one can surround an indium foil withcadmium. The cadmium will absorbneutrons below 0.5 eV, and the indiumfoil (with its huge capture resonanceof 26, 000 barns near 1. 5 eV) can beS-counted by any low background G-Mcounter to detect the beta from 116Indecay after the reaction 115 In (n,y)116In. Accuracies within better thana factor of 2 in flux measurements canbe obtained. A further description ofthis procedure can be found in thearticle by Hankins (Ref. 12).

Intermediate energy neutrons aremost often detected by moderating themdown to the thermal region and thenemploying one of the thermal methodsjust described.

Direct detection of recoils fromneutron scattering does not work well inthis energy region, because it is difficult to observe the recoils againsteven a small gamma ray background. Instead, the most common teclmique is todetect the energetic products of anexothermic reaction such as (n,a).However, the cross sections for manyof these reactions decrease rapidly atenergies above a feweV, and thusneutrons in the keY range are usuallydetected by rather specialized means.

One such teclmique is the so-called''black detector" which absorbs allneutrons within a certain energy region.The most commonly used ''black detectors"are a lOB-doped liquid scintillator ora detector consisting of a boron platewhich uses the associated photon fromthe (n,Y) reaction for detection(Ref. 13). The problem is that theseinstruments absorb all neutrons belowa certain maximum energy. To deriveabsorbed dose-equivalent from fluxdensity involves a detailed knowledgeof the energy spectrum (see Fig. 3).

The moderator approach has beenused with reasonable success. Moderators can be appropriately designedto yield either rem-equivalent responseor flux density response weighted toyeild values of absorbed dose. An

Foil Activation is another commontecMlque for detection of thermalneutrons. Table 1 above showed theproperties of some of the useful reactions. Perhaps the most widely usedfoil material when high sensitivityis required is indium, due to its verylarge thermal neutron cross-section.Use of cobalt is common for the integration"'""O:f'Ji:eutron fluence over verylong periods, because of the long(5.2 year) half-life of 60Co. Gold isused when high precision is requlred,since its capture cross-section is wellbehaved for energies up to about 3 ev.

Thermoluminescence is still anotherdetection techriique for thermal neutrons(Ref. 11). The most commonly usedthermoluminescence detector (TLD) forneutrons is 6LiF, but this detectoralso has substantial gamma sensitivity(Ref. 11). Therefore, it is commonpractice when gamma backgrounds arepresent to use two or three TLD's withvarying fractional concentrations of6Li and 7Li, in order to determine thegamma and neutron contributions separately. TLD's are integrating deviceswhich must be read out in a separateoperation after exposure. The generaldiscussion of TLD's is found in thesection entitled "Personal Dosimetry."The sensitivity of 6LiF is typicallyabove 1000 neutrons/cm2, and the sensitivity to fast neutrons is small.Another common TLD device is CaF2' butit has very small intrinsic neutronsensitivity and large gamma response;addition of lOB or 0Li is used to enhance the neutron response, but withthe exception of pure neutron fieldsit is not recommended.

To summarize the discussion onthermal neutrons, it can be seen thatthere are many methods used for detection; however, complications can arisewhen higher-energy neutrons are present,since most thermal neutron detectorshave at least some sensitivity to higherenergies. When one suspects the presenceof higher-energy fluences, a commontechnique to use is the "cadmium ratio"method. This involves shielding thedetector with a layer of cadmium (anexcellent absorber of neutrons belowabout 0.5 eV) and comparing detector response to the bare situation. To determine

B. Intermediate-Ener~Neutrons(~0.5 eV to 200 ke )

INSTRUM~~TAYIONJFOR ENVIRONMENTAL

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instnunent with the response of Fig. 4has been reported by Leake (Ref. 14);however, the figure indicates a substantial fall-off in sensitivity athigh and low energies, necessitating acorrection for neutrons outside ofthe sensitive range. This device usesa6LiI (Eu) crystal scintillator surrounded by polyethylene moderator.Another instnunent (Ref. 15) uses aboron-loaded ZnS scintillator enclosedin a polyethylene sphere.' Figure 5(from Ref. 15) 'shows the energy responseof this instrument for various moderator thicknesses. Note that the response can be made quite flat. Both ofthese instruments have excellent gammadiscrimination (Ref. 1).

}Q()

~

E~

et

/5()

Q.

&100

5()

.J

RAn-NEUPage 9

Instruments which cover the intermediate range in a rem-equivalentmanner but are also sensitive overmuch broader energies will be discussedbelow in the section on dose-equivalentinstruments.

C. Fast Neutrons (~200 keV to 20 MeV)

In situations where fast neutronsrequire measurement, there is usuallyan accompanying flux of lower energyneutrons, and there may be gamma backgrounds as well. For this reason, afrequently used technique for isolatingthe fast-neutron component is foilactivation, because one can chooseprocesses with a variety of thresholdsand sensitivities.

Neutron energy (fit')

'. )'--/

FIGURE 4: The response of a dosimeter designed to measure dose equivalent ofneutrons in the intermediate energy range.

FIGURE 5: Variation of efficiency and dose dependence of the optimum arrangementwith neutron energy.

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Activation of foils is also usedfor relativistic neutrons. Figure 6shows the cross section as a functionof energy for some of the cOJlllIlonlyused reactions (Ref. 16). Table 2(from Ref. 17) gives some properties ofthe reactions, and the half-lives ofthe activation products.' The last twocolumns. in Table 2 show the sensitivityfor 1 rad, and the backgrol.IDd, for thedetector used by Cross (Ref. 17). Thesensitivity with In, Fe, andZn is perhaps. an order of magnitude better thanfor the fission detectors, because adecay gamma peak stands out above background to a greater extent than whencounting a wide spectrum.

Gas proportional counters whichrely upon the measurement of protonrecoils have found widespread use for

Table 2Properties of Some Threshold Reactions

Reaction Eth T1 /2 a E'Y Sensitivity Background

(MeV) (b) (MeV) for 1" rad (cpm)

(cpm/g)

In116 (n,n t )In116 m 1.2 4.6h 0.3 0.336 121 14

NI68 (n,p)co68 2;6 72 d 0.6. 0.•810 0.63 8

S32(n, p)p32- .

2.9- 1402 d 0.36 ~ 17 1

Zn64 (n. p)Cii643.3 12.8 h 0.26 0.611 27 12

Fe66 (n, p)Mn666.7. 2.6 h 0.08 0.846 56 8

Mg24 (n, p)Na247.2 16 h 0.16 2.76 13 1

AI27 (n, CONa24

1.6 15 h 0.1 2.16 9 1

In1l6 (n, 2n)ln1l410.6 50 d 1.4 0.192 0.46 17

Cu6 6(n, 2n)Cu6411.4 12.8h 1.0 0.611 28 12

NI6 8 (n. np)Co5 7 12 267 d 0.7 0.122 0.58 20

310

FIGURE 6: Response functions of highenergy neutron detectors.

tlrthr c0 60

CoGO GAMMA RAYS

+ Po-Be NEUTRONS

1,000

gaJlllIlaS (at rates from 1 to 100 R/hour)and to the neutron spectrum from aPo-Be source, at rates of 0.001rad/hour. If one is willing to set abias level to eliminate signals fromneutrons below. about 0.5 MeV, .thegaJlllIla discrimination is excellent.

~-t5r Iflr

..--+ 10, I·hr

A-- + 25' I hr....-t 50' I tit

100 - + 100r I hr

~!5ou 10

10,000.---------

Effective threshold energy (in MeV) atwhich cross-section reaches 25% of 0.

uw

'"

Tl/2: Half life of product._0: Average cross-section (in barns) over the

most sensitive energy region.

Ey ; Energy of Decay y (MeV)

Sensitivity: Counts/min per gram of detectorfor 1 rad of neutrons.

Bkgd.: Counter background (cpm).

FIGURE- 7: Integral pulse-height curvesfor mixtures of gamma-raysand fast neutrons.

12 C (n,2n)" C

20g ei (n, fission)

-1 0 1 2 3 4 510 10 10 10 10 10 10

Energy (MeV)

210

-210

fast neutron detection, because of theirexcellent gaJlllIla discrimination. Severalsuch counters have been described inthe literature.. As an example, considerthe counter built at Oak Ridge NationalLaboratory and described by Hurst andWagner (Ref. 18). The counter,~ whichreads out in rads, is completely linedwith polyethylene (CJf2 ) and filled

. with ethylene (C2H4) tona pressure of750 torr. Figure 7 (from Ref. 18)shows the response to 1.3 MeV CoGO

.D 1E 10

'Bee0

Hg (n, ,poll)"' TbuOJ 0 Bf'3

r'" 1:J

'"'"~C,J

-110

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 11

Another counter, filled withmethane-argon, has been described byDennis and Loosemore (Ref. 19). Itsenergy response is shown in Fig. 8.Although this counter has sensitivitywhich is roughly dose-equivalent (rem)in the fast neutron region, it suffersfrom inaccuracies due to a loss ofcounts below the bias level. Theoretical techniques have been developedto estimate corrections for these losses(Ref. 20), but some independent measurements are proba.bly required when theneutron spectnnn is unknown.

0.1

>uc:aJ

~0.05......

MeV

10 20 30 ~05b 6'0 io io 9'0Neutron energy. MeV

I , I

100 110 120

~-

/-- ......../ ........

............... .............. e

................. A............

............

'" Experimental pojnts-eOd irradiation" Experimental POints-sIde irradiation

1 ~ ) ~ 5 6 7 8 9 10 11 12 1) 1, 15 16Neutron Energy MeV

FIGURE 8: Average response of threetype FN 2/3 counters as afunction of neutron energy.The solid line is the responserequired according to the ICRPrecommendations (ICRP Pub. 4)for a counting rate of 0.9c/sec/MPL. The dashed line is thetheoretical response of thecounter for end-on irradiationat a bias level equivalent to0.09 MeV.

Other instnnnents of this type havebeen described by Anderson (Ref. 21)and Murthy (Ref. 22). Murthy's instrument can measure neutron fluxes up to15,000 neutrons cm- 2sec-l. Theseinstnnnents can tolerate (Ref. 1)thermal/fast-neutron dose rate ratiosof about 100/1 and gamma/fast-neutrondose rates of about 200/1.

Another fast-neutron detectiontechnique is scintillation countingwith plastic or liquid scintillatorsattached to a photomultipl1er. Neutrons can be counted in a scintillatorthrough their interaction and productionof secondaries. The enhancement inhigh energy detection efficiency isaccomplished by setting a rather highthreshold. Figure 9 (from Ref. 23)shows the neutron detection efficiencyof a typical liquid scintillator forvarious threshold values.

FIGURE 9: Neutron detection efficiencyof a liquid scintillator,4.7 cm x 4.7 cm, withthresholds of 2,3,4, and 5 MeVelectron energy .

A problem with scintillation count~

ing is that if any relativistic chargedparticles are present, they will countwith nearly 100% efficiency. Thereforeto isolate the neutron component one mu~teither determine that charged particles'are absent or measure them separately.

Unfortunately, the photon responseof some plastics, especially the organicplastics which contain significant fractions by weight of hydrogen, is also verylarge, making them unsuitable where gammabackgrounds are important.

Efforts have been made to overcomethe problem of gamma sensitivity. Themost useful method for distinguishingn:utr<;ll1l? fr?m gammas is pulse shaped1scrlDlmat10n. As an example, VerbinS¥1 et al: (Ref. 24) have successfullyd1fterent1ated the two species in the1 to 10 MeV range using pulse shapediscrimination on the response fromNE-2l3 liquid scintillator manufacturedby Nuclear Enterprises, Ltd. (Ref. 25) •.However, this technique suffers becauseit is delicate, and requires sophisticated electronic equipment.

Another fast neutron detector isthe so-called 'Long Counter' originallydeveloped in 1947 by Hanson and McKibben(Ref. 26), and improved in 1966 byDePangher and Nichols (Ref. 27). TheLong Counter is a BF 3 proportionalcounter surrounded by two concentriccylindrical hydrogenous moderators,with a thermal neutron shield in-between.It has high sensitivity, good gammadiscrimination, and wide energy response(from about 25 keV to 14 MeV). The mostsignificant drawback of the counter isits non-isotropy of response; it is insensitive except for neutrons incidentalong the axis.

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RAn-NEUPage 12

/00 ......----------------------------------,

(p, pnJ

_,-__:..:::.:::.. --.:....:-::...::. {'f1~ ""·nJ----- -----

10

(r.n)

10 100 1000 10000

FIGURE 10: Cross-sections for the production of carbon-II from carbon-12

Another high-energy detection technique depends upon fission. Ionization

This problem of exactly how to weight ameasurement is inherent in all caseswhere.activation is used.

rough check on the possible contributionfrom high-energy neutron fluences. Aquantity termed the "neutron flux density above 20 MeV" can be defined andestimated from the amount of Carbon-IIactivity, assuming an average productioncross-section of 22 mbarns (Ref. 28).The problem is to interpret this"measured" quantity in terms of doseequivalent, which depends upon theassumed spectrum of neutrons. For 20MeV neutrons, the ICRP recommended conversion factor (Ref. 7) states that 4neutrons cm- 2sec- 1 is equivalent to 1mrem/hr (the number is 3.9 at 100 MeV).Various high-energy laboratories haverecommended different conversion factors,which are summarized in the followingtable, reproduced from Ref. 28.:

As in the case of intermediateenergy neutrons, it is possible tomoderate fast neutrons to thermal energies and apply any of the large numberof thermal-detection schemes previouslydescribed. These instruments will bediscussed in more detail in the sectionbelow on dose-equivalent rem-meters.

D. Relativistic Neutrons (Energiesabove 20 MeV)

These neutrons are almost never foundat levels which can pose a potentialhazard to personnel except at high-energyaccelerators. Carbon-II activation(20.4 minute half-lIfe) IS one of themost widely used techniques for measuring the high-energy neutron componentsof a radiation field. A carbon-richdetector is exposed to the radiationfield and the decay positrons (0.97MeV Ema ) are then counted by standardtechnllttles. The threshold for IICexcitation is about 20 MeV, and Fig. 10(from Ref. 28) shows cross-sections forvarious particle types. Note that the(y, n) cross-section is very small.Although the neutron cross-sectionalbehavior overemphasizes the regionjust above threshold, and high-ener¥ycharged particles can also produce lC,this technique is often useful for a

Laboratory

BrookhavenDaresburyCERNRutherfordBerkeley

Flux permrelll/hour

44

103.6 1/4

l2.l/ECMeV)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING"'

RAD-NEUPage 13

500

• Hudis 6 Kotcoff

o Konshin et 01.

o LRL

The generic instrument design is asfollows: a BF 3proportional counter issurrounded by two cylindrical layers ofpolyethylene separated by a 200 mg/cm2

layer of boron plastic. Similar diskscap the ends of the cylinder. TheAndersson-Braun approach was to vary thetwo polyethylene thicknesses, and todrill a variable number of holes throughthe boron plastic layer, until the bestempirical fit to the desired rem-responsewas achieved. Using a BF 3 tube, 2.5cm in diameter and filled to a pressureof 600 torr, the counter was found(Ref. 31) to be insensitive to 137Csphotons (660 keV) up to above 500 R/hour,with neutron sensitivities down to 2mrem/hr full scale. Also, the energyresponse was within ± 10% of rem-equivalent all the way from thermal to 15 MeV,except for a slight region of oversensitivity near 10 keV. This is shown inFig. 12, taken from Ref. 30.

1000,

:0E

b

10

5

<?

I0.1

FIGURE 11: Fission cross sections vs.energy of incident nucleon(neutron or proton) fortargets of U, Bi, Au, and Ta.

E. Dose Equivalent Instruments

chambers lined with bismuth are sometimes used for neutron measurements atvery high energies (Ref. 1). Figure 11(from Ref. 29) shows fission crosssections for U, Bi, Au, and Ta as afunction of energy. Another techniqueis to coat thin evaporated layers ofthese materials on mica, which is subsequently scanned for fission events.To determine the energy spectrum,ratios of fission-probabilities aretaken among the various materials (forexample, U/Au, Bi/Au, U/Ta) , and thedifferent cross-sections of Fig. 11 arethen used to determine the neutronenergy spectrum.

Both foil activation and scintillation counting are commonly used forrelativistic neutron detection; thesehave already been discussed under "fastneutrons".

In this section, instruments will bediscussed which are intended to providea direct measurement of dose-equivalent(rem) over a wide range of neutronenergies. Referring to Fig. 3,_theneutron flux (particles cm 2sec 1) isshown as a function of energy whichprovides proper weighting for doseequiva.lent.

There are several different approachesto the direct measurement of rem. Themost widely used method is the use of asuitably designed moderator surroundinga thermal-neutron detector. There aretwo geometries in common use: cylindrical and spherical. The cylindricaldesign was first described by Andersonand Braun (Ref. 30), who calibrated itusing both thermal neutrons and 25 keVto 15 MeV neutrons. A similar instru-ment was evaluated by Block andPetrock (Ref. 31) who showed that in theintermediate-energy range the responsewas rem-proportional to within ± 10%and directionally isotropic to ± 15%.Another design, by Leake and Smith(Ref. 32), was an improvement overthe original Andersson-Braun instrument.The Block design was in turn modified byTracerlab (now Trapelo West, a divisionof Lab for Electronics). Trapelo Westmarkets the commercially available"SNOOPY" (see the Instrument Note).

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORINGRAD-NEUPage 14

10,--- -,----,

u(]) ,Vl

7

If /uEL=_=_:=_,,=-,_--=-·------- '":"'_,,/RBE DOSE

(Ref. 35) the detector is surrounded by asuccession of polyethylene spheres, 2,3,5,8, and 12 inches in diameter. Figure 13from Ref. 35 shows the relative count ratevs. energy for the various sphere sizes,while Fig. 14 shows the estimated responseof a single 10-inch sphere. While thegamma discrimination is slightly less impressive than for the cylindrical instrument, it is still very good: 5 R/hour ofphotons produces negligible response.That is quite sufficient for most purposes, since one seldom needs to measure1 mrern/hr of neutrons in the presence ofphoton exposure rates as large as 5 R/hr.

10'10'to""' tO~ 10-3 10-2 $0-1

NEUTRON ENERGY (NeV)

o.ot.... .... ....

'"o

NEUTRON ENERGY

"

."lOOeV 10_tV ~ 100"'''

NEUTRON ENERGYIDe"

00 '

o t...===-----ll-,oLO.-:....,.....----,~.O-:-.-::.y-----:-!ID...'

:II" 10o..!i •l;l~ .z

-2 1

~.."~ $.,'" .~

f •.,~ ,

f 0.227 '"ERMAL RESPONSEO. US INVERSE RPG

" ,------;1-,------.,-------,

OJ>;:"'''''..JOJa:

FIGURE 14: Estimated response of a10-inch sphere plottedagainst energy. The pointsshown are experimentalpoints.

FIGURE 13: Relative couting rate plottedagainst energy for moderatingspheres.

The cylindrical instrument is now awidely used survey instrument for mixedfield neutron dosimetrv measurements(Ref.33). It is rugged, portable (about11 kg), and sensitive. It has one important disadvantage: -the electronicsassociated with the BF3 tube cannotfollow extremely brief, high-intensityradiation bursts such as those aroundpoor-duty-factor linear accelerators.A similar instrument is manufactured inBritain by Twentieth Century Electronics,Ltd, of Surrey. Another Andersson-Brauntype detector has been reported by Leake(Ref.34). This instrument, specificallydesigned for use around pulsed-radiationsources, replaces the BFs counter with aBFs-filled ion chamber run in currentmode. The output is measured using ad.c. amplifier with a 30-second integrating time constant. However, thegreatest sensitivity is about an orderof magnitude less sensitive than that ofthe BFs-counter instrument.

The use of a nmber of differentdetectors in spherical geometry wasfirst described by Hankins (Ref.35).The basic instrument is commonly calledthe "Bonner sphere" (Ref. 36): a 6LH (Eu)crystal, 4mm in diameter and 4mm thicksurroUi1ded by polyethylene moderatingspheres. "About 80% of incident thermalneutrons are absorbed in lmm of 6LH, sothat thermal neutron detection isessentially a surface effect, whereasthe efficiency for detection of gammaradiation and fast neutrons is roughlyproportional to the volume of the crystal" (Ref. 36) . In Hankins' description

FIGURE 12: Neutron detection efficiencyas a function of neutron energy.The figures give the countingrate relative to that from acounter with an ideal rem doseresponse of 19 cps/2.5 mrem h.

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The directional sensitivity of thespheres is, of course, essentiallyisotropic except on the side where theelectronic circuitry is located. FromFig. 14 it can be_'seen that if one cantolerate errors of about factors oftwo or three in the fast energy range,a single 10-inch sphere will suffice;the multi-sphere technique JllUst beused when greater precision is required. These spheres are now commercially available, from both Ludlum andNuclear Chicago (see the InstrumentNotes section). Because of the use ofLiI with resolution times of about 1microsecond, these devices suffer froman inability to measure properly inpoor-duty-factor situations, a failingthey share with the cylindrical (BF 3counter) instrument. Eberline manufactures a 9" sphere with a BF3 counter as the detector.

Leake (Ref. 34) has reported aspherical-geometry detector with amoderator similar to the AnderssonBraun .design, except that the boronplastic is replaced by cadmium betweenthe polyethylene layers. The detectoris LiI (Eu) , similar to that of Hankins(Ref. 35) and Bramblett et al. (Ref.36). Commercial manufacturehas beenundertaken by Isotope Developments,Ltd., of Reading, U.K. (Ref. 34).

Nachtigall and Rohloff (Ref. 37)have succeeded in extending the JllUltisphere technique up to an energy of 50MeV, using four spheres of diameter 2,5, 11, and 18 inches.

Dose-equivalent instruments whichemploy several other principles of operation have been reported in the literature. One of these is the use ofgas proportional counters sensitive toproton recoils. These instrumentshave been discussed above under "fastneutrons." They follow the desiredresponse reasonably well up to aboutIS MeV, but are insensitive to neutrons below about 100 keV. Three different efforts to develop so-called"Universal Dose Equivalent Instruments" (not specific to neutrons butrather intended for all types of radiation) have been discussed in the section Particle Accelerators. These arethe approaches of LET spectrometry,columnar recombination in an ion chamber, and use of a liquid-filled ionchamber.

RAD-NEUPage IS

4. SOURCES FOR CALIBRATION OF NEUTRONINSTRUMENTS

Some of the general problems with calibration of instruments have been discussed in theintroductory part of this volume. Here weshall focus attention on a few of the aspectsspecific to the use of neutron sources for calibration purposes.

The central problem in any calibrationmeasurement is to understand the source of neutrons: its energy spectrum, directionality,presence or absence of equilibrium secondaries,and possible secondary sources from scatter ofthe primary neutron flux.

One common calibration technique in thefast-neutron region is the use of radioactiveneutron sources from (a,n) reactions. Considerable research has been done on a determination of energy spectra from these sources, anda review paper by Hanson (Ref. 40) contains anexcellent summary of information up to 1960.More recent work is summarized in ICRU ReportNo. 13 (Ref. 5). The most common sources arePo-Be, Ra-Be, Pu-Be, and Am-Be. Figure IS,from ICRU 134 shows the energy spectrum of neutrons from 2 1Am-Be as measured by severalgroups. The purpose of the figure is to showhow JllUch difference exists among various investigators for Am-Be; this situation is also truefor each of the other sources mentioned. Thespectral uncertainties imply that absolute accuracies better than about ±10% are probablynot achievable with this method; but this isprobably sufficient for most radiation protection work. One remaining problem is that thespectral studies have not generally extendedbelow about 1 MeV, despite the fact that 20 to30% of the neutrons in a typical source are inthat low energy region (Ref. 5). The Am-Besource has one important advantage over theothers, in that there is insignificant contamination from decay of daughters subsequent toAmericium decay.

Fission is another common source of fastneutrons. M>st data on energy spectra seem tofit the Maxwellian distribution fUnction (Ref.5), where E is the fission neutron energy andEn is an experimental parameter:

dN(E)/dE~El/2 exp(-E/E )n .

Experimental numbers for En are in the range1.2 to 1.6 MeV for several fission nuclei l suchas 233U, 235U, 239Pu, 24°Pu, 241Pu, and 252Cf.A compilation of studies on fission spectra wasdone by Barnard et al. (Ref. 41), and summarized in ICRU No. 13 (Ref. 5).

Use of accelerators for production ofnearly mono-energetic neutrons has been common;a wide variety of reactions is available leading to a variety of neutron energies. Figure16 and Table 3~ from ICRU No. 13 (Ref. 5), showthe properties of some of the reactions used.

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RAn-NEUPage 16

16,..-,,..-,-r--,..--,..--,..--,..--.,--,--,---,--.,.--...,.---,---,

1210864

I-~"; \ \.:~. ,-., '\~' /,,-,

\ J \ ;~~~-':""f'~"",,"\\_J \/"1,"\,,

\ I ' ..../ I \\ """'........,V \ \~ /'1'___\ J ~.~J·····t·· '--',\

\/ \". \..... \ ...

2

I'1\I \I \I \I \I \I \I \

JI,.---'"

.•.............

o

12

~

'§,.0

~ 8

sL21"

'"4

Neutron energy. MeV

FIGURE IS: Energy distribution of 241Am-Be neutrons according to differentauthors. The curves have been normalized to give the same totalnumber of neutrons between energies 2.5 and 10.5 MeV: Geigerand Hargrove (1964), proton-recoil counter telescope and time offlight;----Greiss (1968), nuclear emulsions;·····Thompson and Taylor(1965), stilbene crystal with pulse-shape discrimination; -.-.-0-0Salgir and Walker (1967), proton-recoil spectrometer (silicon detector). The dotted low energy peak has been drawn according to thesuggestion of Geiger and Hargrove.

'TABLE 3 -Monoenergetic neutron..producing reactions (allenergies in MeV)

Fig. 16 • Neutron energy spectra resulting from thebombardment of carbon, magnesium, sulphur and silicon withprotons of several energies. (norchers et aI., IOIH. Publisher:North Holland Publishillg Company, Amsterdam.)

51-0'

, 1

'~}

a Measured at 2.0 MeV, 150 degrees.b At bombarding energy = 1.762 MeV.~ At bombarding energy = 2.368 MeV.

Sources of thermal neutrons are usuallymade by the moderat10n of any of the fastneutron sources just mentioned (Ref. 1).Alternatively, a thermal column from areactor can be used. The fluence rate of anyof these thermal sources can be calibrated bythe foils-activation technique; gold foils arecommonly used when high accuracies are required.

Maxi-Maximum mum

Neutron Bom-Minimum Energy at barding

Thresh- Neutron Bombarding EnergyReaction Q-Value ' old Energy Energy for

Energy at 0' Mono-ener-getic

2 MeV 3 MeVNeu-trons

------- --- ----'2D(d,n)3He 3.265 - 1.8- 5.24 6.26 -"T(p, n)3He -0.764 1.019 0.0639 1.20 2.21 -3T(d,n)4He 17.6 - 12.4- 18.25 19.57 3.7'1Li(p,n)7Be -1.647 1.882 0.0294 0.228 1.3 2.38l3C(d, n)14N -0.281 0.328 0.00195 1.6 2.6 3.045SC(p, n)45Ti -2.79 2.908 0.00140 - 0.112 3.67~lV (p, n)51Cr -1.562 1.565 0.00059 0.215b - 2.36<l5CU(p, n)66Zn -2.136 2.169 0.00051 0.214" - 2.29

64

12 Mo<:V11- M4V10 MczV

12 Mqy11 MlzV10 MlzV

2

NEUT?O~ ENERGY, (MeV)

108

C-O'

10sl~

~u..:; 12 ~1';:'1 I> 11 M.V t9 MaV

~ 10· 8 M~V

[5CD

108::;

~::J2

20<r>--=>UJ2

1cf

12 MeV

1d11 MqV10 M4V

0 2 4 6 0

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 17

The directionality of the neutron-sourceis sometimes difficult to determine. especiallyfor thermal neutrons. The important problemhere is the possible presence of scatteredparticles in addition to the primary flux.For accelerator-generated neutron beams thebeam direction is known well. but beam halois difficult to understand or reduce. Forisotopic sources of small size. one can use asmall detector to study departures frominverse-square fall-off of the flux. To minimize scattering problems. the physical layoutof the calibration set-up should be carefullyplanned: for example. apparatus placed neara wall can be subject to large scatteringcorrections. A discussion of this. and ofmethods for measuring the possible scatteringcorrection. can be found in ICRU Report No. 20(Ref. 1).

In all calibrations. cross-comparison withstandard instruments is extremely important.This is necessary to complement the understanding of the properties of the neutron source,because of possible unknown changes in thesource.

As of this time. there does not exist astandard mechanism of calibrations for neutroninstruments through any of the national standards bodies. Further. there are large regionsin the neutron energy spectrum for which nowell-understood neutron sources exist (Ref. 5):this is true in the region around 1 eV. andalso near 2 keV. The available data are poorfor many of the important cross-sections inthe fast neutron region (e.g.,

ICRU Report No. 13 contains a summary ofbasic research (primarily cross-sectionmeasurements) needed to make possible accurateneutron instrument calibrations.

5. SUMMARY AND RECOMMENDATIONS

Neutron monitoring comprises two distincttasks: (a) making detailed area surveys todetermine the properties of the radiationfields; and (b) conducting routine surveillance monitoring. The latter should be supplemented with detailed surveys. undertakenoccasionally and whenever there have beenimportant changes in operating conditions.

The purpose of this section has been toenumerate the various classes of instruments.the conditions under which each class isappropriate and the changes in operation whichrequire a detailed re-evaluation. The readeris directed to the original references forrelevant details about specific techniques.

It is important to remember that whenever anew installation begins operation, itis essential to perform a detailed survey.Thus. separate instruments dominantly sensitive to thermal, intermediate. fast andpossibly to relativistic neutrons are needed,as well as an instrument sensitive to photons.The relative weighting of neutrons in thevarious energy ranges can be assessed usinga combination of techniques discussed in thetext. There should by all means be an overlap in the means of measuring the variousneutron energies to provide some redundancyof information. Also, these spectral studiesare an important aid in studies for reducinglevels for radiation protection purposes.

For routine surveillance an instrumentwhose response is proportional to doseequivalent (rem) is recommended. Among thosecommercially available the cylindricalAnderson-Braun type is widely used, specifically that manufactured by TrapeloWest. Also available are the Bonner-sphereinstruments manufactured by Ludlum. NuclearChicago. and Eberline.

An instrument sensitive to thermalneutrons is frequently required: BF 3 and3He gas proportional counters, boron-linedchambers, LiI(Eu) scintillation detectors.as well as several other types are discussed.Activation of foils is another good techniquefor monitoring thermal neutrons because it isboth simple and sensitive. A variety of foilsapplicable to a wide range of neutron energiesis available commercially. All of thesetechniques are represented among the individual Instrument Notes.

The Indium/Cadmium technique. togetherwith any of the thermal neutron detectors.can be used to provide a rapid assessment offluxes of thermal- and intermediate-energyneutrons.

In the text no attempt has been made tocomment on the commercially available instruments individually: the advantages and disadvantages are discussed in the classes ofdetectors (e.g .• BF 3 tubes). However. sufficient information is not available at thistime to make valid comparisons concerningthe regions of applicability of many instruments. Also. we have attempted to give abrief discussion of some instruments andtechniques which are not now commerciallyavailable. but are worthy of commercialdevelopment.

Finally a comment about electronicsdesign should be made. It is generally truethat monitoring instruments have not yet incorporated a number of the most recent advances in electronic technology. Whenexploited, these advances will lead to manyimprovements: Increased stability and reliability, reduced maintenance, smaller size,

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 18

weight and cost,· and better means of dataread-out. It is urgently recommended thatt~ese improvements be incorporated commerclally wherever possible.

6. ACKNOWLEDGMENT

For this section we particularly acknowledgethe generous advice and review of the following:

Seymour Block, Lawrence Livermore LaboratoryRichard C. McCall, Stanford Linear Accelerator CenterH. Wade Patterson, Lawrence Berkeley LaboratoryRalph H. Thomas, Lawrence Berkeley Laboratory

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

;

v ;) ,J

RAD-NEUPage 19

REFERENCES

ICRU Report No. 20, "Radiation Protection Instrumentation and Its Application",International Commission on Radiation Units and Measurements, 1971

2.

3.

4.

5.

6 .

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

Selected Topics in Radiation Dosimetry, Proceedings of an IAEA Symposium inVienna, June 7, 1960, Internation~l Atomic Energy Agency, Vienna, 1961

Neutron Dosimetry, Proceedings of an IAEA Symposium in Harwell, England,December 10-14, 1962 (2 volumes), International Atomic Energy Agency, Vienna,1963

Neutron Monitoring, Proceedings of an IAEA Symposium in Vienna, 29 August 1966,International Atomic Energy Agency, Vienna, 1967

ICRU Report No. 13, "Neutron Fluence, Neutron Spectra, and Kerma,"International Commission on Radiation Units and Measurement, September 1969

"Second International Conference on Accelerator Dosimetry and Experience",Proceeding; of a Conference at Stanford, November 5-7, 1969, DocumentCONF-691101, U.S. Atomic Energy Commission, Washington, 1969

ICRU Report No.4, "Recommendations of the International Commission onRadiological Protection, Report of Committee IV", Pergamon Press, (1964)

R. Ginther, "Cerium-Activated Scintillating Glasses", page 521 ofReference 2.

M. Bormann et aI, "Flux Mea~urements of Medium Energy I'j"eutrons by Means ofStilbene Scintillators and 't.i Glasses", page 209 of Reference 4.

B. Grimeland et aI, "Measure~ent of Neutron Densities by Activation ofNaI (Tl) CrystalS", p. 377, Vo. I of Reference 3.

J.R. Cameron, N. Suntharalingam, and G.N. Kenney, Thermoluminescent Dosimetry,University of Wisconsin Press, Madison 1968

D.E. Hankins, "Monitoring Intermediate Energy Neutrons", Health Physics ~,

31 (1963)

J.K. Basson,ftCounting Intermediate Energy Neutrons", p. 241, Vol. II ofReference 3.

J.W. Leake, "Calibration of the Neutron Survey Probe 95/0054, ReportAERE-M-1564, U.K. Atomic Energy Research Establishment, Harwell (1965)The figure is from p. 643 of Reference 6.

J.K. Basson, "A Detector for Intermediate Energy Neutrons", Nuclear Ins~ andMethods 22 339 (1963). Another description of the Basson detector is byJ.W. Smith on p. 261, Vol. I of Reference 3.

J.T. Routti, "Mathematical Considerations of Determining Neutron Spectra fromActivation Measurements", p. 494 of Reference 6.

W.G. Cross, "The Use of Mg, Ti, Fe, Ni, and Zn in Fast-Neutron ActivationDosimetry", p. 389, Volume I of Reference 3.

G. Hurst and E. Wagner, "Special Counting Techniques in Mixed-RadiationDosimetry", p. 409 of Reference 2.

J. Dennis and W.R. Loosemore, "A Fast-Neutron Counter for Dosimetry",p. 443 of Reference 2.

R.H. Ritchie, "Calculations of Energy Loss Under the Bias in Fast NeutronDosimetry", Health Physics g, 73 (1958)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 20

21. 1.0. Andersson,"A Proton-Recoil Proportional Counter for Fast Neutron Dosimetry",p. 453 of Reference 2.

22. K.B.S. Murthy et aI, "A Counter for Fast Neutron Dosimetry," Indian Journalof Pure and Applied Physics 5, 26 (1967). A brief description can be foundon page 462 of Radiation Protection Monitoring, Proceedings of Joint WHO-IAEARegional Seminar in Bombay, 9-13 Dec. 1968, International Atomic Energy Agency,Vi enna, 1969.

23. K. Tesch, "Radiation Problems Around the 7 GeV DESY Electron Accelerator,"p. 595 of Reference 6.

24. V.V. Verbinski et aI, "Proton Recoil Neutron Spectrometry with OrganicScintillators",p.151 of Reference 4.

25. Nuclear Enterprise, Ltd., Winnipeg, Canada and Edinburgh, Scotland

26. A. Hanson and J. McKibben, "A Neutron Detector Having Uniform Sensitivityfrom 10 keV to 3 MeV," Physical Review 11..,673 (1947)

27. J. DePangher and L. Nichols, "A Precision Long Counter for Measuring NeutronFlux Density", Report BNWL-260 (1966), Battelle Pacific Northwest Laboratories,Richland, Washington 99352 (1966)

28. A. H. Sullivan, "The Prese::tt Status of Instrumentation for Accelerator HealthPhysics," p. 625 of Reference 6.

29. H.A. Wollenberg and A.K. Smith, "Energy and Flux Determination of High EnergyNucleons", p. 586 of Reference 6.

30. 1.0. Andersson and J. Braun, "A Neutron Rem Counter", Nukleonik §.., No.5,p. 237 (1964). Also reported on p. 93, Vol II of Reference 3, from whichFigure 12 is taken.

31. S. Block and K. Petrock, "Evaluation of a Neutron Rem Dosimeter", UCRL-12167,Lawrence Livermore Laboratory (1964), unpublished.

32. J.W. Leake and J.W. Smith, "Calibration of a Neutron Rem Counter", ReportAERE-R4524, Harwell, U.K. (Her Majesty's Stationery Office, London, 1964),unpubli shed.

33. H.Wade Patterson, Lawrence Berkeley Laboratory, (private communication)

34. J.W. Leake, "Portable Instruments for the Measurement of Neutron Dose-EQuivalentRate in Steady-State and Pulsed Neutron Fields", p. 313 of Reference 4.

35. D. Hankins, AEC Idaho Operations Office Report IDO-16655 (1961), Los AlamosScientific Laboratory Reports LA-2717 (1962), LAMS-2977 (1964), and LA-3700(1968), all unpublished. Also described in Vol. II, p. 123 of Reference 3from which Figurffi 13 and 14 are taken.

36. R.C. Bramblett, R.I. Ewing, and T.W. Bonner, "A New Type of Neutron Spectrometer",Nucl. Inst. Methods ~, 1 (1960)

37. D. Nachtigall and F. Rohloff, Nucl. Inst. and Methods ~, 137 (1967) in German.

38. NCRP Report No. 25, "Measurement of Absorbed Dose of Neutrons, and of Mixturesof Neutrons and Gamma Rays", National Committee on "Radiation Protection andMeasurements, Washington, D.C. (1961). Also published as National Bureau ofStandard Handbook 75.

39. H.H. Rossi, "Ionization Chambers in Neutron Dosimetry", p. 55, Vol. II ofReference 3.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUPage 21

40. A.D. Hanson, "Radioactive neutron sources". Fast Neutron Physics,(J.B. Marion and J.L. Fowler, eds.). Interscience, New York, 1960, Part 1.

41. E. Barnard, A.T.e. Ferguson, W.R. McMurray and I.J. Van Heerden~ "Ti~e-offlight measurements of neutron spectra from fission of 235u, 230U and239pu." Nuclear Physics 71, 228 (1965).

.,")..'j

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

F. INSTRUMENT NOTES: NEUTRONS

RAD-NEUNeutron Monitoring

InstrumentsSeptember 1979

9/79

In this section are found Instrument Notes for those

commercial instruments which are capable of measuring neutrons.

The filing system lists Instrument Notes alphabetically by

manufacturer. These notes include instruments that are

appropriate for neutron spectroscopy as well as dose

equivalent measurements, neutron flux measurements, etc.

3.3.6-i

I

-~

, "

'...l {)u "; " } ,..) ;..J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Neutron Dose-Equivalent MonitorEberline Radiation Monitor ~1-l6

Neutron Rem Detector, NRO-l

RAD-NEllStationary MonitorEberlineJanuary 1978

Class Stationary

Polyethlene (cadmium-loaded) sphere of 9" diameter, BP3 tube inside, usedwith rate meter.



NRD-l:

~-16:

(1)

(2)(1)

(2)(3)

Energy response close to rem-equivalent froin thermal to about10 MeV.Range 1 to 10,000 mrem/hour.Input sensitivity is charge sensitive, adjustable fromapproximately 2 10-13 to 10-11 Coulomb.Range of four logarithmic decades.Window width is adjustable from 0 to at least double the inputsensitivity.

Sampling Continuous

Perfonnance

9/79

NRD-l:

~-16:

(1)(2)(3)(4)(5)(1)(2)(3)

(4)

Gamma rejection up to 500 R/hour dependent on high'voltageAbout 50 counts/minute corresponds to 1 mrem/hour.Plateau approximately 300 volts with a slope of 3% per 100 volts.Directional response within ±10%Operation voltage in typically 1600 to 2000 volts.Response time varies continuously with count rates.Linearity within ~10% of reading typically, ~25% maximum.High voltage regulated and adjustable from less than +200 voltsto +2500 volts.Temperature range is -loC to 60°C (+30oP to ~1400P)

3.3.6.eb-1

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RequirementsNRD-l

Power: 105 = 125V, 60 Hz

Size: 22.9 em diameterX 25.1 emoverall height(9" x 9 7/8")

Weight: 6.25 kg (13 3/4 1b)

RAD-NEUStationary MonitorEberlinePage 2 Jan. 1978

RM-16105 - l25V, 50-60 Hzand rechargeable batteries13.6 em Hx 26.4 em Dx 21. 6 em W (5 3/8"x 10 3/8"x 8 1/2")3.69 kg (8 lbs. 2 oz.)

(),---_/

Features

References

(1) Detector can be wall-mounted(2) Cable up to 100 feet long from detector to electronics package(3) Alarm indication, high, red light and more penetrating tone; low,

blue lamp


Cost NRD-1 Sphere w/cableRM-16 Rate Meter

$695.00$890.00 w/meter face 10472-B42

Address

9/79

Eber1ine Instrument CorporationP.O. Box 2108Santa Fe, NM 87501(505) 982-1881

3.3.6.eb-2

INstku~~N+ATla~ ,;

FOR ENVIRONMENTAL

MONITORING

.J'l

Fast-Slow Neutron Counter

Eberline Model PNC-4

RAD-NEUPortable SurveyEberline 2January 1978

Class Portable, hand-held

9/79



Performance

Requirements

Features

Cost

Address

Uses BF3 slow neutron tube and electronic counter

Neutrons detected: slow and fastRange: 0-500,000 cpm in four, linear, continuously progressive Lin-Log

ranges: 0-500, 500-5,000 0-50,000, and 502000 - 500,000(equivalent to approximately 0-10,000 n/em sec for 1 MeV neutrons)

Linearity: ±.10%Temperature: -40°F to +140°FModerator: Paraffin block enclosed· in a 0.03 inch Cadmium shield in a

0.06 inch aluminum canGannna rejection: Will not detect 60Co gannna radiation below 10R/hr (at

normal setting on detector plateauHigh Voltage: Variable (+1200 volts to +2000 volts) and regulated

Power: Five "D" cells, 200 hoursSize: 22.9 em xlO.2 em x 29.9 em (9" Lx4" WX ll-3/4" H)Weight: 5.44 kg (12 lbs)

The detector may be slipped in or out of the moderator for monitoring fastor slow neutrons, respectively. By correlation of these readings with aknown neutron flux-rate and a known energy, the user may evaluate fast andslow neutron hazards.

$925.00

Eberline InstrumentP.O. Box 2108Santa Fe, New Mexico 87501(50S) 982-1881

3.3.6.eb-3

I-,

Class

; i ..~

INS1RUtvl'EN1"ATlbN '.J

FOR ENVIRONMENTAL

MONITORING

Neutron Rem Counter

Eberline Model PNR-4

Portable, hand-held

RAD-NEUPortable SurveyEberline 3January 1978



Performance

Requirements

Features

Reference

Cost

Address

9/79

Uses a BF3 tube and electronic counter

Energy sensitivity: Thermal to approx. 10 MeVRange: 0-5000 mRem/hr in four, linear continuously progressive, Lin-Log

ranges: 0-5, 5-50, 0-500, 500-5,000 mRem/hr.

Linearity: ~8 of full scale of decade being readTemperature: -40°C to 60°C (-40°F to + 140°F)Ganuna rejection: up to 500 R/hr, dependent on high voltage settingResponse time nominal: 12 seconds, 1st decade

6 seconds, 2nd decade1.5 sec, 3rd decade0.3 sec, 4th decade

Directional response: within ~10%

High voltage: regulated and adjustable, 1300 volts to 2000 volts

Power: Five "D" cells, 200 hoursSize: 43.2 cm x 24.1 em x22.9 em (17" H X 9-1/2" Lx9" W)

instrument 10.2 em W (4")Weight: 8.9 kg (19-1/2 Ibs.)

Detachable detector, lin-log presenation; aural monitoring capability

Manufacturers' specifications

$1125.00

Eberline Instrument CorporationP.O. Box 2108Santa Fe, New Mexico 87501(505) 982-1881

3.3.6.eb-5

1~~TR;YME!'JjTA1JON ,,)

FOR ENVIRONMENTAL

MONITORING

o ',j RAD-NEUDetectorsLNDJanuary 1978

Class


Neutron Radiation Detectors, BF3-He3

Portable, Laboratory

N~utron Detectors

Model

Quadrilateral BF3 Counting Tubes

Outside Dia. Overall Length Operating(on) (inches) (on) (inches) voltage

General Price

220 1. 9x1.2 0.75xO.75 26.0 10.25 1100 Spectrometry221 2.9x2.5 1x1 26.0 10.25 1200 Spectrometry223 3.8x3.8 1. 5x1.5 36.2 14.25 1500 Spectrometry224 5.1x5.1 2x2 36.2 14.25 1500 Spectrometry

Cylindrical 3He Counting Tubes

Model Outside Dia. Overall Length Operating General(on) (inches) (on) (inches) vo1tag~

$400.00400.00550.00500.00

Price

250 2.54 1.0 132.72 52.25 13002501 0.76 0.300 13.02 5.125 1900251 1.35 0.531 15.32 6.032 1000'2510 1.31 0.515 32.22 12.687 22002511 1.31 0.515 21. 75 8.562 2100252 1.31 0.515 36.75 14.562 22002520 2.62 1.031 26.04 10.25 12752521 2.62 1.031 24.45 9.625 12752522 2.62 1.031 27.14 14.875 34002523 2.62 1.031 42.38 16.687 34002524 2.62 1.031 57.62 22.687 34002525 2.62 1.031 29.21 11.50 13002526 2.62 1.031 34.29 13.50 13002527 2.62 1.031 39.37 15.50 1300253 5.16 2.031 26.04 10.25 15002531 5.16 2.031 29.53 11.625 4800254 5.16 2.031 17.46 6.875 4800255 4.45 1. 75 21.11 8.312 1500

Quadrilateral 3He Counting Tubes

Model Outside Dia. Overall Length Operating(on) (inches) (em) (inches) voltage

262 2.54x2.54 1x1 26.04 10.25 1500263 5.1 x 5.1 2x2 36.8 14.50 2000275 1.9 x 5.1 0.75x2 11.1 4.375 170027510 1.9 x 1.97 4.75 1900-2150

Cylindrical BF3 Counting Tubes

Model Outside Dia. Overall Length Operating(on) (inches) (on) (inches) voltage

Flux MappingTime of FlightMonitoringTime of FlightTime of Flight SpectroscopyTime of Flight SpectroscopyMonitoringHigh TemperatureTime of Flight SpectroscopyTime of Flight spectroscopyTime of Flight SpectrsocopyIndustrial GagingIndustrial GagingIndustrial GagingMonitoringSpectrometryDiffractionHigh Temperature

General

SpectrometrySpectrometryBeam MonitorBeam Monitor

General

$400.00325.00300.00350.00350.00375.00400.00400.00550.00650.00825.00825.00875.00

1000.00725.00750.00875.00400.00

Price

$550.001250.00

750.00550.00

Price

200 2.24 0.875 132.40 52.125 1200 Flux Mapping201 1.35 0.531 15.40 6.062 1600 Monitoring2011 1.35 0.531 19.70 7.75 1200 Monitoring20110 1.32 0.519 19.70 7.75 1050 Survey Instruments202A 2.62 1.031 30.80 12.125 1100 General Purpose202S 2.62 1.031 30.80 12.125 1100 General Purpose2021 2.70 1.062 14.61 5.75 1600 AV/PDR-7020210 2.62 1.031 35.48 13.97 1700 General Purpose2022 2.62 1.031 20.00 7.875 1700 General Purpose2023A 2.62 1.031 40.32 15.875 1200 General Purpose2023S 2.62 1.031 40.32 15.875 1200 General Purpose

3.3.6.1n-19/79

$350.00130.00130.00130.00150.00150.00185.00150.00150.00175.00175.00

~..

INSTRUMENTATION

FOR ENVIRONMENTALRAD-NEUDetectors

MONITORING LNDPage 2 Jan. 1978

Cylindrical BF3 Counting Tubes (continued)

Model Outside Dia. Overall Length Operating General Price/-~\

(em) (inches) (em) (inches) voltage I,)

2024 2.62 1.031 60.64 23.875 1200 General Purpose $175.002025 2.62 1.031 30.48 12 1200 Reactor Source Range 175.002026 2.62 1.031 76.52 30.125 1200 Reactor Source Range 175.00202ER 2.62 1.031 37.78 14.875 1600 Diffraction 550.00203S 5.16 2.031 40.32 15.875 2200 General Purpose 190.00203A 5.16 2.031 40.32 15.875 2200 General Purpose 190.002031 5.16 2.031 27.94 11 3000 AN/PDR-58 550.0020310 5.16 2.031 64.45 25.374 2700 General Purpose 225.002032A 5.16 2.031 30.56 12.375 1300 General Purpose 225.002032S 5.16 2.031 30.56 12.041 1300 General Purpose 225.00212E 5.16 2.031 33.63 12.031 2500 Diffraction 750.00212ER 5.16 2.031 39.69 28.25 2500 Diffraction 750.0020327 2.0 2200-2900 Low energy neutron detection 200.00

lOB Lined Proportional Counters

Model Max. Dia. Overall Length Operating Sensitivity Price(em) (inches) (em) (inches) voltage (cps/nv)

230 1. 35 0.531 As Specified 700 0.6 $350.00232 2.54 1.0 20.00 7.875 800 1.0 300.0023210 2.54 1.0 38.74 15.25 950 4.0 400.0023211 2.54 1.0 76.2 30.0 800 10 475.0023011 1. 27 0.50 29.61 11.656 600-900 0.6 300.0023110 1. 27 0.50 69.06 27.188 600-950 7.5 300.0023113 1.27 0.50 160.82 63.313 600-950 7.5 500.00

Proton Recoil Fast Neutron Detectors

Model Max. Dia.. Overall Length Operating voltage Price(em) (inches) (em) (inches)

270 4.10 1.615 11.75 4.625 1500-3200 $400.002801 5.08 2.00 17.15 6.75 1400 350.002802 5.08 2.00 20.80 8.19 1400 400.002803 5.08 2.00 31. 75 12.50 1400 430.002804 5.08 2.00 53.72 21.15 1400 475.00281 3.81 1.50 25.40 10.0 2500 300.002821 2.54 1.0 17.15 6.75 1100 300.002822 2.54 1.0 20.80 8.19 1100 330.002823 2.54 1.0 31. 75 12.50 1100 400.002824 2.54 1.0 53.75 21.15 1100 440.0028114 5.1 2.0 70.00 27.75 2500 250.0028115 5.1 2.0 85.34 33.6 2500 285.00

Fission Counter

Model Max. Dia. Overall Length Operating Remark Range Price(em) (inches) (em) (inches) voltage

3075 0.64 0.25 2.54 1.0 200-800 Stainless 103 to 108n $640.003076 1. 27 0.5 13.97 5.5 200-800 Aluminum 103 to 108n 700.-725.003078 5.08 2.0 30.48 12 200-800 Aluminum 103 to 108n 850.00

3.3.6.1n:"'2

9/79

IN~+RU~rv1EN,JATI~ ",J

FOR ENVIRONMENTAL

MONITORING

RAD-NEUDetectorsLNDPage 3 Jan. 1978

One-dimension Position Sensitive Proportional CounterModel Max. Dia. Overall Length Operating voltage

(em) (inches) (em) (inches)Anode Price

2522525228252292523026211

2.542.542.542.547.62

1.01.01.01.03.0

112.40112.40

43.1843.1825.40

744.2544.2517.0017.0010.00

10001000100010001000

quartzmolecul--

quartzmolecul--molecul---

$1800.001800.001200.001200.005000.00

Reference

Address

9/79

Manufacturers' specifications

LND3230 Lawson Blvd.Oceanside NY 11572(516) 578-6141Telex 14-4563

3.3.6.1n-3

,,)_) \J "j 0INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Neutron Spectrometer

Ludlum Model 42-5

IOOfV I ~tN IO"'tV .... IOOk~"'"

NEUTRON ENERGY

RAD-NEUSpectrometerLudlum 4January 1978

IMev 10M-tV IOOMfV

Class


9/79

Relative counting pate plotted against enepgyfop modepating sphepes.

Mobile

Six different diameter spheres moderate various energy neutrons LiI (Eu)crystal, light pipe and RCA 6199 photollUlltiplier tube to be used with anycounting system capable of accepting 2 millivolt minillUlrn signals andproviding 900 V dc to the detector

3.3.6.lu-l

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NEUSpectrometer

. Lud1tml 4Page 2 Jan. 1978


Sampling

Sphere Diameter (in)

2358

1012

Continuous

Energy Range

See Figure

Performance Accuracy: Efficiencies, response time, etc. (see references)

Requirements Power:Size:Weight:

900 V dc to be supplied by counting system112 em H x 45 em Wx 52 em D (45" x 18" WX 21" D)

55 kg (120 1bs)

Features

References

Cost

Address

X-ray inspection of all spheres insures void-free moderators. A crankoperated elevator assembly adjusts detector center from 44 to 73 inchworking height.

a) Mdhufacturers' specificationsb) D. E. Hankins, "The Multisphere Neutron-Monitoring Technique,"

Los Alamos Report LA-3700, UC-41 Health and Safety, TID-4500,Los Alamos, New Mexico 1968.

$1,695.00

Lud1tml Measurements Inc.501 Oak StreetSweetwater, Texas 79556(915) 235-5494

3.3.6.1u-2

INhRclME~TAtiON"') bFOR ENVIRONMENTAL

MONITORING

1

f

Neutron C01.Ulters

N. Wood Models

RAD-NEUC01.UltersN. WoodJanuary 1978

9/79

MN-1

MN-1

MN-3

G-S-1

G-S-2

G-S-3

G-S-9

G-S-9

G-S-16

G-10-2

G-10-ZA

G-10-S

G-10-S

G-10-S

G-10-12

G-10-1ZA

G-10-20

G-1S-S

G-1S-7H

G-1S-34A

G- 20- 5

G-20-12

3.3.6.nw-1

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Neutron Counters

N. Wood Models

RAD-NEllCountersN. WoodPage 2 Jan. 1978

/_.)..(0 ...

'. ---.-/

Class


Portable, Laboratory

BF3 Neutron proportional counters

ACTIVE OPERATINGMODEL DIAMETER LENGTH VOLTAGE GENERAL PRICE

MN-1 V4" v. " to 5" 1100 to 2000 volts, Pigtail lead. Microneutron counters for $100.00MN-3 v. " as for 20 to 60 em. Hg. 931 /U connector. reactor instrumentation. $200.00

specified. pressure of SF,. (MN-3 has 5/16"casing up to 56"long.)

$100.00G-5-3 5/S" 3" 1400 to 2100 volts, 931 /U connector. Small generalG-5-9 or 9" for 20 to 60 em. Hg. Caps same 0.0. pu rpose neutron $107.00G-5-12 V2" as 12" as counter. detectors. $113.00G-5-16 specified. 16" $120.00G-10-2 1" 2" 1300 v. for 20 em. Hg. Pigtail lead. Widely used in $107.00G-10-2A 1" 2" 1800 v. for 60 em. Hg. 931 /U connector. portable instruments. $120.00G-10-5 1" 4%" 1500 to 2200 v. for 20 HN 82-805 Standard multiple

$133.00G-10-12 1" 12%" to 60 em. Hg. For or purpose neutron ,G-10-20 1" 20" lower oper. volt. 931 /U connector. detectors. $147.00 )

specify small dia. $160.00anode.

G-15-5 1V2" 5" 1700 to 2250 v. for 20 HN 82-805 Standard research $133.00G-15-12 1V2" 12" to 45 em. Hg. Higher or counters. High sensitivity $167.00G-15-20 1V2" 20" pressure may be 931 /U connector. low background. $187.00G-15-34A 1%" 34" specified as well as [G-15-34A was developed for cosmic radiation $233.00

lower voltage. studies (Simpson counter).]

G-20-5 2" 5" 1900 to 2300 v. for 20 General purpose high sensitivity detectors. $153.00G-20-12 2" 12" to 45 em. Hg. Higher Useful in moisture meters and environmental $187.00G-20-20 2" 20" pressures and lower monitoring. Connectors sa~e as above $213.00IG-20-38 2" 38" voltages may be models. $247.00

specified.

Prices listed are for brass or copper cathode, prices for aluminum cathode - add $10.00; pricesfor stainless steel on request.Prices listed for Model G (Enriched BF3 - 97% Boron 10) are the same for Model F (Depleted BF3 11% Boron 10).

Address

9/79

N. Wood Counter Laboratory, Inc.1525 E. 53rd StreetChicago, Illinois 60615(312) 324-1114

3.3.6.nw-2

\-~ ~ ,) i'-•.) 't.) ~,)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Reactor Experiments, Inc.

RAD-NEUFoilsReactor ExperimentsJanuary 1978

Class Portable

Principle Neutron dosimeter foils 12.7 nnn (0.5") diameterof Operation

NominalThickness Purity Price per

Material Cat. No. (nnn) (inches) (percent) Box of 10

Aluminwn 505 0.76 0.030 99.963 $60.00Aluminwn 505A 0.13 0.005 99.991 55.00Alwnimun 505B 0.05 0.002 99.999 65.00Arranoniwn-

Sulfate 538A. 3.2 0.125 99.998 65.00

Cadmiwn Cover Set 53lA 1.0 0.040 99.9 $70.00Cadmiwn Cover Set 531 0.5 0.020 99.9 55.00

Cobalt 50M 0.05 0.002 99.896 $85.00Copper 509A 0.25 0.010 99.998 65.00Copper 509 0.13 0.005 99.998 70.00

Copper 509B 0.013 0.005 99.997 $ 70.00Dysprosiwn 581 0.025 0.001 99.995 125.00

Gold 521B 0.025 0.001 99.995 $100.00Hafniwn 553 0.05 0.002 99.957* 140.00Indiwn 501 0.03 0.005 99.99 65.00

Iron 515 0.13 0.005 98.643 $ 95.004.45% Lutetiwn-

Alwninwn 508 0.1 0.004 99.963 180.00

~)Magnesiwn 514 0.13 0.005 99.781 60.00

*Includes 2.94% Zirconiwn

9/79 3.3.6.re-1

$INSTRUMENTATION RAD-NEUFOR ENVIRONMENTAL FoilsMONITORING Reactor Experiments

Page 2 Jan. 1978

Reactor Experiments, Inc.

NominalThickness Diameter Purity Price per

Material Cat. No. (rrnn) (inches) (rrnn) (inches) (percent) Box of 10

80.2%Manganese-Copper 516 0.05 0.002 99.722 $65.00

Molybdemun 527 0.075 0.003 99.985 60.00NeptWlium-237 578 50 jlg cm2 19 0.75 275.00/foilNickel 5l3A 0.25 0.010 99.981 60.00

Nickel 513B 0.075 0.003 99.981 $65.00Niobium 576 0.13 0.005 99.837 85.00Plutonium- 239 575 30 jlg cm2 19 0.75 99.22 275.00/foilRhodium 540 0.025 0.001 99.97 145.00Scandium 580 0.13 0.005 99.64 225.00Silver 511 0.13 0.005 99.96 65.00

Sodium Chloride 543B 2.0 0.075 99.99 $65.00Sulfur

(I" diam.) 522A 4.75 0.187 99.99 60.00Sulfur 522B 0.075 99.99 55.00Tantalum 534 0.13 0.005 99.98 65.00Thorium 5l2B 0.1 0.004 99.885 65.00

Tin 551 0.1 0.004 99.57 $60.00Titanium 535 0.25 0.010 99.876 105.00Tungsten 526 0.15 0.006 99.96 115.00Uranium

(natural) 503 0.175 0.007 99.97 110.00Uranium

(depleted) 504L 0.025 0.001 99.958 145.00 for5 foils

Uranium30 jlg/cm2(enriched) 577 19 0.75 99.06 275.00/foil

Vanadium 517 0.075 0.003 99.968 75.00Zinc 552 0.13 0.005 99.99 75.00Zirconium 541 0.13 0.005 99.82 75.00

Features Each foil is thoroughly cleaned and accurately weighted to 0.0001 g with aweight code ernbosed directly on the foil and 28 page "Foil InstructionManual". Flux wires, fission foils, and cadmium tubing is also available.

Address Reactor Experiments, Inc.963 Terminal WaySan Carlos, CA 94070(415) 592-3355

9/79 3.3.6.re-2

· ,,-~-,J .-;)

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Neutron Survey Meter

Victoreen Model 488A

Portable, handheld

RAD-NEDSurveyVictoreenJanuary 1978


Uses a 4" boron-lined neutron proportional counter, moderator, amplifier,ratemeter, meter readout

0-800 cpm0-8,000 cpm0-80,000 cpm0-800,000 cpm 2thermal neutrons/em /sec,


Range: Thermal to 14 MeVThermal neutrons, four ranges:

These ranges correspond to 0-12xl, x20, xlOO, xlOOO.

Gannna Sensitivity: Completely insensitiveR/hr.

to gannna radiation fields to 500

Sampling

Performance

Requirements

Jeatures

9/79

Continuous

Accuracy: ±.10% fullscale deflectionTime Response: Switch selected, 1.5 seconds,S seconds, 15 secondsModerator: high density polyethylene encased in 1/32 in. cadmiwn chilled.

2.54em (1 in.) wall thickness overall moderator diameter7.9em (3 1/8").

Drift: less than 5% over 24 hoursTemperature operating range: -30°C to +50°C

, -20oP to +120 oPTemperature dependence: less than 5% over above temperature rangeHLunidity range: 0-90%

Power: Two "D" cellsSize: 30. 5em LxII. 4cm Wx 25. 4em H (12" x 4 1/2" x lO")Weight: 3.85 kg (8.5 lbs)

The detector assembly may be utilized in three modes -- either bare tube,tube with polyethylene moderator, or tube with moderator and cadmiwn shield.With these combinations the 488A detects thermal neutrons, moderated fastand thermal neutrons, and only fast neutrons respectively.

3.3.6.vi-l

-~-I

Cost

Address

INSTRUMENTATION

FO R ENV I RONM ENTAL

MONITORING

$1,090.00

Victoreen Instrument Division10101 Woodland AvenueCleveland, Ohio 44104(216) 795-8200

RAD-NEllSurveyVictoreenPage 2

9/793.3.6.vi-2

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

PERSONNEL DOSIMETRY

RAn-DOSPersormel DosimetryPage 1

1. Introduction

2. Design Considerations

3. Dosimeter Types

4. Gamma/Beta Dosimetry

a. Filmb. TLDc. Pocket Ionization Chambersd. Other Dosimeters

(i) RPL(ii) TSEE

\(iii) Track Etching}

5. Neutron Dosimetry

a. Fast Neutron Detectorsb. Thermal Neutron Detectorsc. Albedo Dosimetry

6. Special Dosimetry Problems

7. SlDlDllary

8. Acknowledgment

9. References

) ,.J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING .

i} ./I

RAD-DOSPersonnel DosimetryPage 3

1. INfROruCTION

In this section we shall discuss instrumentation used to measure integrated externalradiation doses to personnel. The archtype ofsuch instnnnentation is the "film badge", butof course this discussion will be of broaderscope; we shall deal with the general measurement problem of integrating dose instnnnentsdesigned to be pinned to clothing, carried inpockets, worn on fingers, or otherwise portablewithout the user's constant attention or evenconstant consciousness.

There are several reasons why such instruments are used. Perhaps the most commonlyexpressed reason is related to legal liabili ty:in routine use at low integrated dose levels,the dosimeter protects the employer againstliability for negligence, and is in many casesrequired by law for just such a purpose. Asecond important motivation, and certainly theprime operational motivation, is the assessment of dose in the event of an accident, asthis can be a crucial aid in post-accidenttreatment. Third, when doses may approachmaximum permissible levels, dosimeters areoften used to limit individual exposures.Finally, the psychological benefit of dosimetryis often cited; some individuals ignorant asto the true meaning of radiation dose somehowfeel "safer" wearing a dosimeter, as if "bigbrother" were looking after them.

2. DESIGN CONSIDERATIONS

Each of these motivations places a differentset of constraints upon the dosimetry system.Thus the whole question of accuracy is relatedboth to the legal-liability situation and tothe requirements imposed by decision-makingin post-accident treatment. Also, the desirability of long-term dosimeter storage forlegal purposes is sometimes cited. Further,the portability required of the dosimeter imposes size-and-weight restrictions, while costconsiderations demand that large numbers ofreadings be possible at low unit-cost. All ofthese factors must be considered in any discussion of personnel dosimetry.

Obvious ly, "the more accurate the better".However, certain basic limitations prevent theattainment of extremely precise measurements.The most important is the problem of sampling.A dosimeter can only measure the radiationwhich strikes it, but the problem arises whenone relates the dosimeter reading to an"equivalent whole body external dose." Severalfactors contribute here; for example, lowenergy beta activity in the air can register ina sensitive dosimeter and yet be effectivelyshielded by a couple of layers of clothing.Also, the angle of incidence of the radiationis important: exposures from one side of thebody may be misrepresented by some dosimeter

geometries, especially if the dosimeter is atthe front while radiation is incident at theback of the body. Another problem occurs whendose is delivered to a part of the body (e.g.,hands or feet) distant from the dosimeter.

Dosimetry thus presents a nearly impossibleproblem if accuracies in the few-percent rangewere to be required. Fortunately, no such needexists, from the viewpoint of either postaccident treatment or legal responsibility.

To illustrate these point~, we shall quotefrom ICRP Publication 12 (Ref. 1):

"A dosemeter carried on the surfaceof the worker's body is best regarded asa sampling device. It provides a sampleof the dose received at the surface of thebody during the movement of the workerthrough his environment. It does notprovide a direct measurement of the radiation dose to organs or tissues, except forthe dose to the skin in the immediatevicinity of the dosemeter. Neither doesit necessarily provide an adequate assessment of the situation i:1 the workplacebecause it measures the dose only at onepoint on the body of each worker.

"It is only in exceptional cases,usually associated with substantialaccidental exposures, that attempts needbe made to estimate the actual organ doses,rather than doses at the surface of thebody. The greatest uncertainties in theassessment of organ doses from routinemonitoring are caused by the fact that asmall number of dosemeters, often onlyone, has to be taken as representative ofthe exposure of the whole surface of thebody. Unless the dosemeter results arerepresentative, there is little point inconducting detailed calculations of thedepth dose in a composite, finite medium- - the human body.

"The need to use many dosemeters andthe complexity of the necessary interpretation to assess the actual organ dosesprohibit the making of these assessmentsas part of routine individual monitoring.A simplified system of interpretationhas to be adopted•.• and this will usuallyhave the effect of assessing upper limitsto organ doses rather than actual values •..

"It has become conventional to noteand record all radiation doses above thethreshold of detection of the personaldosemeter. This detailed attention to lowdoses may, in some cases, focus unrealisticattention onto exposures which, if theycause any risk at all, cause risks whichare trivial in comparison with other risksof life. Other exposures, often of thesame order of magnitude, are not recorded,

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING


either because they are below the thresholdof detection or because the individualsare not monitored. The Commission [ICRP]has now recomnended that individual monitoring and associated records are notneeded if the doses are most unlikely toexceed 3/10 of the annual Maximum Permissible Doses. It is possible to makeuse of this recommendation to makeindividual monitoring simpler and morelogical •••

"In principle, the choice of aninvestigation level would correspondexactly to 3/10 of the appropriate annualMaximum Permissible Dose •.•

"In practice, however, such a preciseequivalence cannot be achieved becausemost individual monitoring for externalradiation is carried out over periodssubstantially shorter than a year. It istherefore recommended that, for thewhole body, the investigation level forpenetrating radiation should be set somewhat lower--50 mrem for a dosimeterissued for 2 weeks, 100 mrem for 1 month,or 300 mrem for 3 months. In the rarecases when a substantial part of the doseto an individual results from neutrons orfrom internal contamination, the investigation level should be applied to thetotal recorded dose in a control periodrather than to each of the separatecontributions .••

"The uncertainties acceptable inroutine individual monitoring should besomewhat less than the investigationlevel and can best be expressed in relation to the annual dose. The uncertaintyin assessing the upper limits to theannual dose equivalent to the whole bodyor to the organs of the body•.• shouldnot exceed 50%. Where these doses areless than 2 rems an uncertainty of 1 remis acceptable. This uncertainty includeserrors due to variations in the dosemetersensitivity with incident energy anddirection of incidence, as well asintrinsic errors in the dosemeter andits calibration."

For the purposes of our discussion here,suffice it to say first that the obviousaccuracy limitations on external personneldosimetry must be recognized by the user;second, that when high accuracies are requiredother methods must be called upon to complementthe dosimeters of concern here; and finally,that most people realize that the need forgreat intrinsic accuracy is not the mostsignificant factor in the choice of dosimeters.

What is important is an assurance thatno substantIal component of the absorbed doseis missed entirely by the dosimetry system

being used. Thus one needs to base a dosimetry system upon detailed information aboutthe types of radiation likely to be encountered.

We shall concentrate here upon a discussionof the tUJes of dosimeters; their relativesensitivltles to various particle species andenergy ranges; and their advantages and disadvantages.

3. DOSIMETER TYPES

For routine daily monitoring, there aretwo basic types of dosimeters in common usetoday: film and thermoluminescent dosimeters(TLD' s). --nlm is the more commonly used, andhistorically has been the mainstay of personneldosimetry systems. TLD's are now achievingincreasingly widespread use. The most importantsubject of debate today in this field seems toconcern the relative merits of film and TLD.

Several other types of dosimeters arealso in use, usually for special applications.Among these are pocket ionization chambers,activation detectors, radiophotoluminescent(RPL) dosimeters, and thermally-stimulatedexoelectron-emission (TSEE) devices.

We shall attampt here to discuss the basicproperties of each of these various types, aswell as their various regions of applicability.We shall also indicate those new techniqueswhich show possible promise for dosimetry, butstill require extensive investigations anddevelopment.

There are two basic types of externalradiation fields which are commonly monitored:beta/gamma and neutron fields. We shall discussthese separately, Slnce the latter involvestechniques and considerations completelydifferent from the former.

4. GAMMA/BETA DOSIMETRY

A. Film

The basic property of film dosimetersis the ionization-induced darkening of emulsion.The intrinsic limitations of film are due tofour problems: first, some (unavoidable)background darkening occurs in the absence ofany ionization; second, film must be wrappedto avoid light leaks, and even for thinwrappings the dosimeter is typically insensi-tive to alpha particles, low energy betas, andlow energy x-rays; third, the high atomicnumber of typical emulsions makes the responsenon-tissue-equivalent for low-energy photons;and finally, emulsion darkening ultimatelysaturates at high doses.

;) ..~,-r"

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAn-DOSPersonnel DosimetryPage 3

1. INTRODUCTION

In this section we shall discuss instrumentation used to measure integrated externalradiation doses to personnel. The archtype ofsuch instrumentation is the "film badge", butof course this discussion will be of broaderscope; we shall deal with the general measurement problem of integrating dose instrumentsdesigned to be pinned to clothing, carried inpockets, worn on fingers, or otherwise portablewithout the user's constant attention or evenconstant consciousness.

There are several reasons why such instruments are used. Perhaps the most commonly.expressed reason is related to legal liability:in routine use at low integrated dose levels,the dosimeter protects the employer againstliability for negligence, and is in many casesrequired by law for just such a purpose. Asecond important motivation, and certainly theprime operational motivation, is the assessment of dose in the event of an accident, asthis can be a crucial aid in post-accidenttreatment. Third, when doses may approachmaximum permissible levels, dosimeters areoften used to limit individual exposures.Finally, the psychological benefit of dosimetryis often cited; some individuals ignorant asto the true meaning of radiation dose somehowfeel "safer" wearing a dosimeter, as if ''bigbrother" were looking after them.

2. DESIGN CONSIDERATIONS

Each of these motivations places a differentset of constraints upon the dosimetry system.Thus the whole question of accuracy is relatedboth to the legal-liability situation and tothe requirements imposed by decision-makingin post-accident treatment. Also, the desirability of long-term dosimeter storage forlegal purposes is sometimes cited. Further,the portability required of the dosimeter imposes size-and-weight restrictions, while costconsiderations demand that large numbers ofreadings be possible at low unit-cost. All ofthese factors must be considered in any discussion of personnel dosimetry.

Obviously, "the more accurate the better".However, certain basic limitations prevent theattainment of extremely precise measurements.The most important is the problem of sampling.A dosimeter can only measure the radiationwhich strikes it, but the problem arises whenone relates the dosimeter reading to an"equivalent whole body external dose." Severalfactors contribute here; for example, lowenergy beta activity in the air can register ina sensitive dosimeter and yet be effectivelyshielded by a couple of layers of clothing.Also, the angle of incidence of the radiationis important: exposures from one side of thebody may be misrepresented by some dosimeter

geometries, especially if the dosimeter is atthe front while radiation is incident at theback of the body. Another problem occurs whendose is delivered to a part of the body (e.g.,hands or feet) distant from the dosimeter.

Dosimetry thus presents a nearly impossibleproblem if accuracies in the few-percent rangewere to be required. Fortunately, no such needexists, from the viewpoint of either postaccident treatment or legal responsibility.

To illustrate these points, we shall quotefrom ICRP Publication 12 (Ref. 1):

"A dosemeter carried on the surfaceof the worker's body is best regarded asa sampling device. It provides a sampleof the dose received at the surface of thebody during the movement of the workerthrough his environment. It does notprovide a direct measurement of the radiation dose to organs or tissues, except forthe dose to the skin in the immediatevicinity of the dosemeter. Neither doesit necessarily provide an adequate assessment of the situation i:1 the workplacebecause it measures the dose only at onepoint on the body of each worker.

"It is only in exceptional cases,usually associated with substantialaccidental exposures, that attempts needbe made to estimate the actual organ doses,rather than doses at the surface of thebody. The greatest uncertainties in theassessment of organ doses from routinemonitoring are caused by the fact that asmall number of dosemeters, often onlyone, has to be taken as representative ofthe exposure of the whole surface of thebody. Unless the dosemeter results arerepresentative, there is little point inconducting detailed calculations of thedepth dose in a composite, finite medium- - the human body.

"The need to use many dosemeters andthe complexity of the necessary interpretation to assess the actual organ dosesprohibit the making of these assessmentsas part of routine individual monitoring.A simplified system of interpretationhas to be adopted... and this will usuallyhave the effect of assessing upper limitsto organ doses rather than actual values •..

"It has become conventional to noteand record all radiation doses above thethreshold of detection of the personaldosemeter. This detailed attention to lowdoses may, in some cases, focus unrealisticattention onto exposures which, if theycause any risk at all, cause risks whichare trivial in comparison with other risksof life. Other exposures, often of thesame order of magnitude, are not recorded,

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAn-DOSPersonnel DosimetryPage 4

either because they are below the thresholdof detection or because the individualsare not monitored. The Conunission [ICRP]has now recomnended that individual monitoring and associated records are notneeded if the doses are most unlikely toexceed 3/10 of the annual Maximum Permissible Doses. It is possible to makeuse of this recommendation to makeindividual monitoring simpler and morelogical. ••

"In principle, the choice of aninvestigation level would correspondexactly to 3/10 of the appropriate annualMaximum Permissible Dose •••

"In practice, however, such a preciseequivalence cannot be achieved becausemost individual monitoring for externalradiation is carried out over periodssubstantially shorter than a year. It istherefore recommended that, for thewhole body, the investigation level forpenetrating radiation should be set somewhat lower- -50 mrem for a dosimeterissued for 2 weeks, 100 mrem for 1 month,or 300 mrem for 3 months. In the rarecases when a substantial part of the doseto an individual results from neutrons orfrom internal contamination,the investigation level should be applied to thetotal recorded dose in a control periodrather than to each of the separatecontributions .••

"The uncertainties acceptable inroutine individual monitoring should besomewhat less than the investigationlevel and can best be expressed in relation to the annual dose. The uncertaintyin assessing the upper limits to theannual dose equivalent to the whole bodyor to the organs of the body•.• shouldnot exceed 50%. Where these doses areless than 2 rems an uncertainty of 1 remis acceptable. This uncertainty includeserrors due to variations in the dosemetersensitivity with incident energy anddirection of incidence, as well asintrinsic errors in the dosemeter andits calibration."

For the purposes of our discussion here,suffice it to say first that the obviousaccuracy limitations on external personneldosimetry must be recognized by the user;second, that when high accuracies are requiredother methods must be called upon to complementthe dosimeters of concern here; and finally,that most people realize that the need forgreat intrinsic accuracy is not the mostsignificant factor in the choice of dosimeters.

What is important is an assurance thatno substantIal component of the absorbed doseis missed entirely by the dosimetry system

being used. Thus one needs to base a dosimetry system upon detailed information aboutthe types of radiation likely to be encountered.

We shall concentrate here upon a discussionof the tlPes of dosimeters; their relativesensitivltles to various particle species andenergy ranges; and their advantages and disadvantages.

3. DOSIMETER TYPES

For routine daily monitoring, there aretwo basic types of dosimeters in common usetoday: film and thermoluminescent dosimeters(TLD's).-n:tm is the more commonly used, andhistorically has been the mainstay of personneldosimetry systems. TLD's are now achievingincreasingly widespread use. The most importantsubject of debate today in this field seems toconcern the relative merits of film and TLD.

Several other types of dosimeters arealso in use, usually for special applications.Among these are pocket ionization chambers,activation detectors, radiophotoluminescent(RPL) dosimeters, and thermally-stimulatedexoelectron-emission (TSEE) devices.

We shall attampt here to discuss the basicproperties of each of these various types, aswell as their various regions of applicability.We shall also indicate those new techniqueswhich show possible promise for dosimetry, butstill require extensive investigations anddevelopment.

There are two basic types of externalradiation fields which are commonly monitored:beta/gamma and neutron fields. We shall discussthese separately, since the latter involvestechniques and considerations completelydifferent from the former.

4. GAMMA/BETA IXlSlMETRY

A. Film

The basic property of film dosimetersis the ionization-induced darkening of emUlsion.The intrinsic limitations of film are due tofour problems: first, some (unavoidable)background darkening occurs in the absence ofany ionization; second, film must be wrappedto avoid light leaks, and even for thinwrappings the dosimeter is typically insensi-tive to alpha particles, low energy betas, andlow energy x-rays; third, the high atomicnumber of typical emulsions makes the responsenon-tissue-equivalent for low-energy photons;and finally, emulsion darkening ultimatelysaturates at high doses.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-OOSPersonnel DosimetryPage 5

The advantages of film include the abilityto re-scan emulsions after an exposure todetennine details of dose depositions; use offilter shadowing and exposure-uniformity information to measure directionality of exposureand source distance; and the very wide varietyof possible film types and grades (although inactual fact the variety of films now commercially available is quite limited).

The dynamic range of the more sensitivefiims is typically from a few mrad to a fewthousand mrad, with films available which respond up to the megarad region; the typicaldosimeter system might use films of both themost and least sensitive types in order tocover as large a dynamic range as possible.Film's linearity of response (emulsion densityvs. dose) is excellent, tmtil saturation setsin at the high-dose end. This is illustrated

The intrinsic accuracy of film is quitegood. In one study (Ref. 6) tmder carefullycontrolled conditions, and changing films everyweek, x-ray exposures to Kodak Type 3 film of10 to 200 mR/week (0.5 to 10.0 R!year) havebeen determined to ~ ±20% for a single filmand $ ±10% (standard deviation) on a quarterlybasis. For a single 10 mR exposure, standarddeviations of ±25% are possible. Of course,such "carefully controlled conditions" are nottypical of actual operational use. One veryimportant quality-control practice is to setaside and develop a few blanks and controlledexposure films with each new batch of emulsions,to detennine if any changes in sensitivity haveoccurred. The main point to be made here isthat intrinsic accuracy is not a significantcontributor to error in the use of film dosimeters.

54

2S KVCP. IlVL 0.17 MM AL

2 3STORAGE TIME (weeks)

X-Rays:

Effect of 75 to 95% humidity, 23 to32°C on optical density of KodakType 2 Film, as a fW1.otion of storagetime (from Ref. 14).

/ ./

,/< .,'~.

,,' C Kodak Convnerical, 14lt x 17" Ready Pack,Behind KK in Same Pack

° Kodak Industrial M, 8" x 10" Ready Pack

UNSEAL1EDI

- -

""o OUTDOORS STORAGE• LAB STORAGE

" SEALED

", • OUTDOORS STORAGE• LAB STORAGE

" JDAK PERSONlL MONITORING,,

FILM TYPE 2

'" EM. NO. 204701

"'........

1 Ry

(GOeo)

........"- r---,

- 75-95'70 RELATIVE.......,

HUMIDITY, 23-32°e """"----......;.-I "

~eKGR~~ (FOG) DEN11TY0.2

o

0.4

in Figure 1 (from Ref. 7).

1.0

>fiiizwo

<I 0.6u;::co

ORNL-DWG 71-7775

Exposure (R)

FIGURE 1. Optical density against roentgenexposure plotted on linear grid for KodakCorronercial film and for Kodak Type M filmsin Ready Packs (from Ref. 7).

O.B

The humidity and temperature effects aresignificant, however. StudIes of DuPont 555and Kodak Type 2 films have shown rapid lossesof up to 40% in sensitivity at high humidity(Ref. 8). The effect is probably on latentimage fonnation, possibly from "the action ofthe various radiolytic products of water uponthe silver halide crystal, affecting either themigration of conduction band electrons, thefraction of silver ions free to migrate to thesensitivity centers, or both" (Ref. 8). Figure2, from Becker (Ref. 14) shows the effect of 75to 95% humidity, 23 to 32°C on optical densityfor a typical film.

FIGURE 2.

3

the physical or engineering contwo other properties of film are

low unit cost, and long-termre-measurement and legal record-

Besidessiderations,often cited:storage (forkeeping).

Here we shall present data about sometypical films to indicate the approximateranges of various parameters. We shall nottry to discuss and compare all of the variouscommercially available films and film services;because of their large number, that would bean almost insurmomtable task. Suffice it tosay that film badge services have come underthe study of the International Atomic EnergyAgency (IAEA) and the U.S. Public HealthService, and documents containing overviews ofthe important considerations have been in theopen literature for several years (Ref. 2, 3,4). Also, a 1962 book by Becker (Ref. 5) contains an excellent summary of the basic properties and considerations in film dosimetry.

The three basic operational characteristics to consider are accuracy, dynamic range,and energy response.

)

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The non-unifonnity of photon sensitivityof films as a function of quantum energy isconsidered by some to be their greatest drawback. At low energies, the intrinsic sensi-tivity of emulsions is much larger than atmedium energies, in some cases by pig factors.Much effort has gone into the design of varioustypes of filters to coq>ensate for this energydependence.

A typical example of the use of filtersfor decreasing the energy dependence is thework of Storm and Shlaer at Los Alamos (Ref. 9).Figure 3 shows the way in which the unfilteredresponse is modified by using filters with oneelement (Bi), two elements (Bi, Er) and sixelements (Bi, Au, Ta, Er, Cd, and Nd). Theidea is that the incident x-rays are attenuated by the K-edge absorption of each successivematerial, decreasing the effective dosimetersensitivity. Figure 4 shows the measuredresponse of four commercial films using thistechnique. Use of a lead frame back wasnecessary to eliminate a scattering problem inthe plastic encasing the filters.

'0

The conclusion of Storm and Shlaer is thatit is possible to eliminate much variation insensitivity at the low energies in film dosimeters, at least down to energies of a few tensof keV. It should be noted that multi-filterholders are relatively expensive, which hasdiscouraged their wide use. At the other (high)end of the energy scale, response becomes poorat energies high enough that particle-equilibriumis not established upstream of the dosimeter(of course, this is true for all dosimetersunder consideration in this section).

B. TLD

Thermoluminescent dosimetry (TLD) isbecoming more and more widely used for routinegarrana/beta dosimetry. The basic physicalprinciple is now reasonably well understood.Ionizing radiation incident upon a crystalelevates an electron from the valance band tothe conduction band, leaving a hole in thevalance band. The electron and the hole movethrough the crystal until they either recombine

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FIGURE 3. The photon response ofDuPont 502 fi lm unfi Zteredand filtered by one-, twoand six-element filters(from Ref. 9).

ON[·£I..£MENT FilTER' 0.'67 O/c",' SiTWO-ELEMENT FinER: 0268 O/tm' Oi ANO O.I~6 Olem t ErSIX-! LEM£NT Fit1£ R; 0.013 o/c:rn "ai,01l6 O/c.,,1 Au. 0.1116 oleml To.

o.o~e g/crn' £', 0.014 0/(11'1 Ode AND 0.049 0/,,,,1 'rut

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FIGURE 4. Response of DuPont 508 and555, Eastman Type II andIZford PM-l films in thelead-frame plastia badge(from Ref. 9).

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FIGURE 5. Useful range of TID and film (fromRef. 15).

The destructive readout is intrinsic to themethod. One heats up the TLD chip, measuresthe integrated signal, and is than ready tore-use the chip. Systems are now commonly usedto semi-automate the process; however, allinformation is lost, and in the event of somefailure there is no second opporttmity to fallback upon, except the back-up chip alreadymentioned.

Still another advantage of TLD is itssensitivity to betas. LiF can be fabricated invery thin layers, and requires little wrapping,so that beta dosimetry is quite feasible.

Perhaps the two main reasons cited atlaboratories where TLD has not replaced film areits difficulties when neutrons are present, andits destructive readout. We shall discuss theneutron measurement problem separately below.

r=1=f-I-

102 10'Exposure (rem)

10

In perusing the literation on TLD, one isimpressed by a tremendous amotmt of enthusiasmfor TLD among its proponents. This impressioncan be had from even a brief study of the proceedings of recent conferences on the subjectof TLD (Ref. 12,13,14). We would like toemphasize here that both film and TLD seem tohave some advantages in partlcular situations,and can be used to complement one another formixed-field dosimetry.

The advantages of TLD over film areseveral: (a) reproducible accuracies tmderlaboratory conditions have been achieved at the±5% level; (b) the dynamic range is large, withdoses of from a few mrem to many thousand remmeasurable in the same crystal; (c) directionaltmiformity surpasses that of film: it is easierto design a dosimeter to reduce the directionaldependence to ±20% down to low x-ray energies;(d) fading is minimal: TLD's do not fade significantly with extreme climatic conditions;(e) energy response is more tmiform at low xray energies; (f) TLD dosimeters are rugged andreusable.

or are trapped in metastable states, usuallyassociated wi th impurity sites. When thecrystal is heated, sufficient energy may begiven to the electron (or the hole) so that itwanders arotmd, eventually recombining with acotmterpart hole (or electron). The recombination energy is released as visible light(a thermoluminescent photon).

A good description of basic TLD dosimetrycan be fotmd in the excellent book by Cameron,Stmtharalingam, and Kenney (Ref. 10). Also,Cameron has compiled a bibliography on thesubject (Ref. 11).

The disadvantages include the destructivereadout (once read out, the information is lost);the inability to determine directionality ofdose deposition; and slightly higher costs thanfilm. The commonest way to avoid the problemof data lost by accident is use of a back-upchip; this is now fotmd in many sys tems .

The most common thermoluminescent crystalused today is lithium fluoride. There is extensive documentation of the properties of LiF; weshall try to show some of the typical data.For example, Figure 5 (Ref. 15) shows that theuseful range of LiF extends up beyond 10 5 rem;a typical sensitive film is shown for comparison. The linearity of response is good,extending down to below 10 mrem on the low-doseend. The directional sensitivity is shown inFigure 6 (Ref. 15); again, the tmiformity isexcellent.

The energy response of a typical TLD isshown in Figure 7 (from Ref. 16). The enhanced sensitivity in the 20 keV region ismuch more easily handled by filtering techniques than is the (more extreme) problem withfilm.

Another frequently cited "disadvantage" ofTLD (compared to film) is the legal, recordkeeping requirement. The argument is given thatpossession of the actual exposed film dosimeteritself is somehow intrinsically preferable tothe mere record from a TLD reading. However, itis now generally recognized that well-maintainedrecords are sufficient evidence in any legalsituation (Ref. 17).

The "fading" problem is an important consideration if dosimeters are not changed often.There are many situations in which large groups

O'

~~---:!=--~---b;;;;-;~~.TLD

Badge

FIGURE 6. TLD dosimeter response VS. angleof incidence (from Ref. 15).

I

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ENER G'I RESPONSE

500

400 -

... ~k- 300c::>l- i 1-2-~ 2...'"'" 200..'"

100

Energy (MeV)

FIGURE 7. Energy Response of TLD-700thermoluminesaent material (fromRef. 16).

of employees are monitored with no expectationthat any detectable exposure will occur. Forexample, at Lawrence Livermore Laboratory,semi-annual or annual processing cycles weredesired for many employees whose exposure riskis minimal, but it was estimated that "themaximtnn period that film should be used isthree months. In practice, a one-month exposureperiod was never exceeded because of the significant aging and fading characteristics ofthe film dosimeter" (Ref. 18). The fading ofLiF, by contrast, is considered to be of onlyminor concern. However, in order to doublecheck for anomalous or incorrect readings, aback-up TLD chip (of calcium fluoride, CaF2)is used at Livermore; it is read out only inthe event of such an anomaly (Ref. 18).

In addition to LiF, several other TLDmaterials have been studied and applied inpersonnel dosimetry. Among those in use todayare CaF2:Mn, caS04:Tm, CaS04:Dy, A1203, andfluorite. Some of these are used in combination with or as back-ups for LiF. Some ofthem also have properties which are improvements over one or more of the less desirablecharacteristics of LiF.

For example, although LiF is subject totribothermoluminescence (mechanically inducedluminescence) and other possible spuriousluminescence, CaS04:Dy is significantly lesssusceptable: a factor of 30 less tribothermoluminescent response was measured in onestudy (Ref. 19). Also, this study showedexcellent low-dose sensitivi ty for caS04:Dy(down to ~0.2 mR), which can be of occasionalusefulness in dosimetry.

Another drawback of LiF is that its thermoluminescence is strongly dependent upon the

thermal history of the material (Ref. 20, 21),so that the annealing technique must be quitecarefully controlled. This is much less trueof CaF2:Mn and caS04 dosimeters.

C. Pocket Ionization Chambers

A frequently-used back-up or auxiliarydosimeter is a pocket ion chamber, usually pensized. It is typically used to assess (in situ)the dose being received by a worker in a--high-radiation-level environment. These instruments are understood to be for x and gannnaradiation only (although many will respond aswell to beta radiation), and to be capable ofeither direct read-out or immediate indirectread-out with a separate instrtnnent.

Specifications for such dosimeters haverecently been established by the AmericanNational Standards Institute, Subcommittee N13.5(Ref. 22). The electrodes of the ion chamberform a capacitor which is charged to a predetermined voltage; ionization occurring inthe chamber surrOlmding the electrodes causesa decrease in the charging voltage which canbe read by an electrometer; or alternativelycauses motion of a movable electrode, whichmotion can be read directly.

A typical instrument today can measureexposure (Roentgen) to about ±15% of full scalefor 200 mR full scale settings, and undergoesdischarge (leakage) at rates of at most a fewtenths of a milliroentgen per hour, for 200 mRfull scale (Ref. 22). Since it is meant foruse on at most a daily (8-hour or perhaps24-hour) basis, it is a very useful instrumentfor daily or even hourly dose assessment.Pocket ion chambers can now be obtained in avariety of rugged, sealed, environment-insensitive design; their disadvantage is an almosttotal insensitivity to betas, alphas, and neutrons.

D. Other Dosimeters

Several dosimetry techniques are nowin the research-and-development stage, and arenot yet fully operational. Among the conceptsbeing studied for gannna dosimetry are radiophotoluminescence (RPL) and thermally stimulatedexoelectron emission (TSEE). Neither RPLnor TSEE is now used in any commercially available systems.

(i) RPL

In radiophotoluminescence, radiationproduces defects in a solid (usually aglass); ultraviolet light can subsequentlybe used to produce fluorescence in theglass. The amount of fluorescence isrelated to the radiation absorbed. UVstimulation is not a destructive readout,however, which is a clear difference from

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FIGURE 8. Typical absorption and luminescencecurves for an RPL glass:(A) absorption characteristics priorto irradiation, (B) absorption afterirradiation, (C) luminescence produced by illumination in the absorption band (from Ref. 23).

TLD. On the other hand, because dose iscontinually integrated an RPL dosimetereventually saturates and must be discarded.

that radiation impinging on the TSEEmaterial elevates an electron from thevalance band to the conduction band,leaving a hole in the valance band. Theelectron and hole move about until trappedin impurity sites. When the crystal isheated, the electron may pick up enoughenergy to overcome the work-function andbe emitted: hence, thermally-stimulatedexoelectron emission. The number ofemitted electrons is measured in somec0unting or integrating device (e.g.,G-M tube, ionization chamber).

Reviews of recent research in TSEEdosimetry have appeared in the two mostrecent conferences on TLD (Ref. 13, 14).Becker (Ref. 29, 30) has also recentlyreviewed the subject. Among the featureswhich commend TSEE are extreme sensitivity(down to even the 10-6 R region); significantly reduced problems with poor crystalpuri ty; low background and "pre-dose"characteristics; the small thickness of thesensitive layer (perhaps less than 10 nm);and the possibility of excellent energyresponse down to low x-ray energies, by theuse of several materials. The disadvantages,at present, include poor "fading", so thatreadout must take place within at most afew days of exposure; and the more complicated read-out system required. At present,TSEE still requires consIderable work onboth the basic physics and the engineeringdetails, before it can supplement themore widely-used systems.

~o...N

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Figure 8 (Ref. 23) shows the absorption and luminescence response curves forone typical RPL glass.

Most RPL glasses suffer from fadingover long periods of time. Anotherproblem is the "pre-dose" RPL, which isthe amount of response even before irradiation. Today, pre-doses equivalent to afew hundred mrad are about the lowestavailable (Ref. 24). Among the glassesbeing investigated are aluminum andlithium phosphates and lithium borate,all doped with silver phosphate. Figure9 shows the calculated energy dependenceof a lithium borate RPL glass containingvarious amounts of AgP03' It can be seenthat this material is quite energyindependent down to a few tens of keV.Among other drawbacks (Ref. 26) of glassdosimeters are the poor sensitivity toSIS of encapsulated glasses; and therelative insensitivity to low energyx-rays (~50 keV).

Recent stnnrnaries by Cameron (Ref. 23),Becker (Ref. 24, 27) and Yokota (Ref. 26)can be consulted for more detailed information about RPL. We will summarize hereby stating that RPL has several attractivefeatures, which still require developmentwork to produce a workable beta/gammadosimetry system.

2400

(ii) TSEE

10 100

PHOTON ENERGY (kllll

1000

Thermally-stimulated exoelectronemission (TSEE) is a process quite similarphysically to thermoluminescence; indeed,many substances exhibit both TSEE andthermoluminescence. The basic concept is

FIGURE 9. Calculated energy dependence of alithium borate RPL glass containingdifferent amounts of silver phosphate(from Ref. 23).

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(iii) Track Etching

This technique relies upon the factthat certain materials suffer local radiation damage from very high-LET radiation,the sites of which are preferentiallyattacked by certain etchants. This technique, which is principally used forneutron dosimetry, will be discussedbelow under "Thermal Neutrons".

5. NET.ITRON DOSIMETRY

The problem of neutron personnel dosimetryis discussed separately from the gamma/betaproblem for three reasons: First, a largefraction of radiation exposure involves noneutron fluxes at all; second, the presentinstrumentation for neutron dosimetry is inmany important cases not adequate to the task,unlike that for gamma7oe"ta dosimetry; andthird, the dosimetry of high-LET radiations(of which neutron dosimetry is but one part)has been of increasing concern in recent years.

For details on the various energy divisions, properties, and relative importances ofneutron fluences, the reader is referred to"Neutron Monitoring" elsewhere in this volume.In what follows here, we shall assume afamiliarity with that section.

Baarli (Ref. 31) has discussed the problemof personnel dosimetry in mixed radiationfields around high-energy accelerators; theconclusion is drawn that present techniquesare adequate only if the approximate composition and energy spectra of the componentradiations are understood reasonably well.

At the present time, separate dosimetersare in common use for thermal and for fastneutron detection. Intermediate-energy----personnel dosimetry is not often attempted,and high-energy neutron personnel dosimetry isperformed using techniques (mainly, foilsactivation) already described in detail in"Neutron Monitoring."

There are basic physical reasons for thedifficulty in monitoring intermediate-energyneutrons using a portable dosimeter. Thermalneutrons can be captured in materials withhigh thermal-neutron cross-sections, and fastneutrons can be detected by the chargedsecondaries produced in (n,p) interactions inhydrogenous (or other 10w-3) material. However,neutrons in the intermediate-energy region(between -0.5 eV and -200 keY) are not easilydetected except by the use of a moderator anda thermal-neutron detector.

As discussed in "Neutron Monitoring,"relatively few situations exist in which a

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5.0

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0.1

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--Predicted responsef Experimental points

----rem per track unit for o·trockunit exposure" (1.67 x 107~

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FIGURE 10. Response of NTA paakets to neutrons of various energies (fronl Ref. 32).

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60

80a (degrees)

5040

60

30

40

20

ANGLE OF HIULSlON PLANE TONEUTROIl INCIDENCE DIRECTION

20

10TII~E ELAPSED BEn-IEEN EXPOSURE AND DEVELOPI~ENT (DAYS)

_. D, c"

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FIGURE 12. NTA fi lm badge pesponse as a functionof neutpon incidence angle (fPomRef. 35).

Figure 13 (Ref. 35) shows the effect of70% relative humidity on latent image stabilityof NTA film. Desiccation followed by the heatsealing of Kodak NTA Type B film in moistureproof bags has been successfully used forseveral years by a British group. Theirunpublished results (Ref. 45) show that the2- to 4-week latent-image half-life of NTAfilm can be extended to about 8 weeks usingthis technique. The bags are made of alaminate of paper/0.012 mm Al foil/polyethylene.~mrshall and Stevenson (Ref. 36) have consideredthe edge-effects problem in scanning of emulsion,while Oshino (Ref. 37) has studied the energydependence of NTA worn on a phantom.

103

to hydration at high humidities, which increasesthe hydrogen content and hence the fast-neutronsensitivity. This and other problems (temperature effects, storage problems) have beendiscussed by Lehman (Ref. 32) and others(Ref. 33, 34, 35). Figures 11 (Ref. 34) and12 (Ref. 35) show the fast-neutron response ofNTA film as a function of incident angle.

INCIDENCE OF NEUTRONSI. NORMAL 10.012 ANGULAR Ie .31i3. PARALLELle.90i

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o 1 2 3 , S S 1 8 9 10 11 12 13INCIOENl NEUTRON ENERGY IN (MeV I

We shall begin by discussing fast-neutronand then thermal-neutron dosimeters, and finallybody backscattering and albedo dosimeters.

substantial fraction of the dose is from thermalneutrons; the main exception-rn-near a thermalcolumn at a reactor. However, thermal-neutrondetectors are important because many indirectmethods of assessing higher-energy neutronfluences actually rely on thermal-neutrondetectors.

The basic technique most commonly usedfor fast neutrons (-200 keV to -20 MeV) is thenuclear track emUlsion. A typical emulsion ofthis type is Eastman Kodak Type A (often called"NTA") emulsion, which has been described indetail by Lehman (Ref. 32) and Becker (Ref. 5).NTA is a special fine-grained film, typically25 to 35 microns thick. Neutrons are detectedby the trail of ionization from charged particles released by one of three mechanisms:(a) elastic (n,p) interactions with hydrogen,which register in NTA above about 0.4 MeV;(b) exoergic (n,p) reactions with nuclei, whichregister in NTA below about 10 eV and then onlyon nitrogen nuclei; and (c) inelastic nuclearinteractions resulting in a "star", significant about 20 MeV.

The energy response of NTA is shown inFigure 10, from Lehman (Ref. 32). The sensitivity is seen to be significant only forfast and thermal neutrons. Standard practiceis to report the response of neutron film intracks per unit area, as seen through a microscope. There are difficulties in relating themeasured quantities to neutron flux (and henceto dose-equivalent), mainly because some ofthe response comes from interactions in theemulsion wrapping, and some from interactionsin the emulsion itself; varying emulsionthicknesses (batch to batch) complicate calibration procedures. One problem with thisclass of detectors is that it is susceptible

FIGURE 11. Estimated NTA film pesponse (fPomRef. 34).

FIGURE 13. Effect of 70% peZative humidity onZatent image stability of NTA film(fPom Ref. 35).

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Although fast neutron dosimetry has beencarried out for almost two decades using nucleartrack emulsions, it is clear that some featuresare in need of improvement. However, insituations where neutron spectra are known tobe dominated by fast neutrons, and where highhumidity is not a problem, this technique canbe used with reasonably good results.

Two other methods of fast neutron personneldosimetry involve foils activation or fissionfragment foils, in either case resulting indarkening of film by charged particles (fromdecay or fission fragments). These will betouched on briefly in the next section, onthermal neutron detectors.

B. Thermal Neutron Detectors

Thermal J'l~utron personnel dosimetry iscommonly performed today with one of threemeans: thermoluminescent dosimeters, fissionfoil dosimeters, or film surrounded by a foilwhich is activated and then decays.

The commonly used TLD method relies upontwo isotopic compositions of lithium fluoride,6LiF and 7LiF. Lithium-6 has a thermal-neutroncross-section of about 960 barns for the process 6Li(n,a)3H; the cross-section of lithium-7is smaller by a factor of about 25,000. The7LiF TLD responds to photons with the characteristics already described, while the 6LiFresponds to both photons and thermal neutrons.Harvey et al. report that the response of a6LiF TLD to 1 rem of thermal neutrons isapproximately 80 times the response to 1 R ofgamma radiation (Ref. 28), and that the minimumdetectable thermal neutron dose is $0.5 mrem.However, "it is necessary to calibrate eachbatch of 6LiF separately, as significant differences in sensitivity may occur betweenbatches, and the ratio of neutron to gammasensitivity is not constant" (Ref. 28). Fastneutron sensitivity of LiF is insignificant."The response in equivalent gamma rads per fastneutron tissue rad is roughly proportional toneutron energy, ranging from 1% at 1 MeV to10% at 10 MeV" (Ref. 28).

Many of the basic advantages of and problems with TLD's are identical to those of TLD'sin general, which have already been discussed.

The fission foil technique exploits theproperty of certaInC:rystalline materials,plastics, and glasses, whereby radiation damagesthe materials so that certain etchants willpreferentially attack the damaged areas. Inparticular, some materials only produce "tracks"(etched pits or holes) when the linear energytransfer (LET) exceeds some critical rate.Neutrons themselves, and gammas, do not providethe minimum LET, while fission fragments do;hence, the fission fragment technique, in whicha fissionable foil is placed next to a plastic

detector, and the integrated thermal neutronfluence subsequently determined by etchingand microscopic scanning or electroniccounting. Typical track sizes of 0.1 ~ areobserved. Becker (Ref. 38) has prepared areview of track etching.

These dosimeters are relatively unaffectedby humidity, hi§h temperature, and mechanicalshock. Using 2 sU, detection limits of aslow as 10-6 rem have been reported for thermalneutrons (Ref. 30); and using other nuclides(238U, 232Th, 237Np) with thresholds in theMeV region, detection limits in the 0.5 to 1 mremrange for fast neutrons are also reported. Adiscussion by Unruh gives some of the importantconsiderations in applying this technique(Ref. 39). Another discussion by Widell(Ref. 40) indicates that mica is an excellentsubstance for image formation, but that residualtrace uranium in some natural micas producesa high latent background, which must be "erased"before use by baking for several hours at 500°C.

Still another thermal-neutron technique isactivation. One approach uses film surroundedby cadffiium, with emulsion darkening from thegammas due to the reaction 113Cd(n,y)11~Cd

(Ref. 34). Unruh, et al. (Ref. 39) describe asystem in which a series of three foils isactivated, with subsequent exposure of emulsionby foil decay. The three foils are tin-rhodium(sensitive to gammas, thermal, and "bodymoderated" fast neutrons), cadmium-rhodium(gammas, "body moderated" fast neutrons), andtin-iron (mainly gammas). The various radiations are determined independently using threefilm-darkening measurements, and by solving aset of simultaneous algebraic equations.

C. Albedo Neutron Dosimeters

A fundamental consideration in neutronpersonnel dosimetry is that of backscatter oralbedo. We quote from Hankins (Ref. 41):

"When the human body is exposed toneutrons, some of the incident neutronsare backscattered to create a flux ofneutrons of various energies leavingthe body. These neutrons are called

-albedo neutrons, and a dosimeter placedon the body to measure this flux of backscattered neutrons is called an albedoneutron dosimeter. Such dosimeters areusually designed to detect thermalneutrons, and when cadmium is used toeliminate incident thermal neutrons,the dosimeter response is largely fromthe thermal neutrons that return fromthe body."

The power of albedo dosimetry is that ithas sensitivity in the energy range where veryfew other techniques work: for intermediate-

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6. SPECIAL DOSIMETRY PROBLEMS

FIGURE 14. Response of atbedo dosimeter wozon onthe body as a funation of inaidentneutron energy (from Ref. 28).

neutrons exceeds that to the albedo fromincident 10 keV neutrons by a factor of about10. The dosimeter was designed to modify thisresponse to decrease the thermal and epithermal sensitivity: hence the boron. Theresulting sensitivity is shown in Figure 14(Ref. 28). Note that the sensitivity isreasonably flat from thermal energies to 10 keV,which is a wide range indeed.

IOOeV IK'" 10K'" lOOK'" I MoVNEUTRON ENERGY.

10'"10.V·OI.V O·l.V

Although the most common monitoring problemin personnel dosimetry is whole-body exposures,there are often requirements for dosimetry inother situations. Perhaps the most familiarof these is measurements of doses to theextremities (particularly to the hands).

For this purpose, several specially designed classes of integrating dosimeters havebeen developed. Thus, dosimeters to be wornon the fingers are now in common use, and dosimeters for mounting in shoes have also beendesigned.

Here we will not treat these in detail;instead the reader is referred to the literature. The main operational difficulties withsuch instruments are related to the validityof the measurement: the accuracy of theparticular dosimeter used is by no means themost important consideration. For example,dose may be accrued through contact with radioactive material, a common problem in radiochemistry laboratories. Here even fingerdosimeters can give incorrect results in manycases, since low-energy betas can give surfaceskin doses undetectable by some dosimeters.

The main point to be made here is thatusers must investigate very carefUlly theparticular radiation field being monitored, toassure that the measured dose is meaningfullyrelated to the dose received.

The energy dependence as found by Hankinsshows a monotonic decrease of a factor of about10 between 200 keV and 3 MeV neutron incidentenergies, with comparably high sensitivitiesfor the intermediate and 200 keV cases.

energy neutrons (-0.5 eV to -200 keV). Thereare many situations in which a significantfraction of the dose equivalent is from intermediate-energy neutrons, and in which personneldosimetry is desired.

Unfortunately, many of the albedo-neutrondosimeters in present use have a significantenergy dependence, which decreases their usefulness in situations where the neutron energyspectrum in unknown. Where the spectrum isknown, correction factors can be applied tocompensate for energy dependence and arrive ata reasonably accurate (±30%) dose-equivalentmeasurement.

A recent study by Hankins (Ref. 41) examinedthe way in which various design parametersaffect dosimeter response. flankins used smallTLO chips (6LiF) encased in various thicknessesof 2" diameter polyethylene (CH), all surrounded by cadmium. He studied the effects ofplacement of the TLO in front of, within, andbehind the CH, and the effect of removing thecadmium on the back of the badge. His mostimportant conclusion was that almost none ofhis parameters significantly affected the ratherlarge energy-dependent sensitivity. On thepositive side, he found that adding CH increasedthe dosimeter sensitivity; that with totalencasement of cadmium the sensitivity is notsignificantly affected by distance away fromthe body, at least up to 3 em; that sensitivityis greatly affected by shielding thicknessbetween source and dosimeter; that if cadmiumis not present on the back (body side), mostof the response is from albedo rather thanincident neutrons, except for thermal neutronexposures on a totally cadmium-enclosed dosimeter; and that the placement of both 6LiF and7LiF chips in the same or equivalent positionsis critical.

Similar results have been reported byHoy (Ref. 42) at Savannah River, where one ofthe main monitoring problems is around a~lutonium production plant, with a typical

38PuF4 neutron spectrum mainly between 0.3and 25 MeV. The dosimeter (a 2"-diametertwo-section concentric hemisphere, separatedby cadmium, using 6LiF and 7LiF TLO, and wornon a belt) gave adequate dose-equivalent measurements.

Another albedo dosimeter has been developedin the United Kingdom (Ref. 28). TLD's (6LiFand 7LiF) are housed in a plastic cover loadedwith boron carbide. The design criterion wasas follows: for an unshielded l/velocity (l/v)detector at the surface of the body, theresponse to the albedo from incident thermal

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FOR ENVIRONMENTAL

MONITORING


A discussion of finger dosimetry can befound in Ref. 43 and 44.

7. SUMMARY

The aim of this section has been to discussinstrumentation for the measurement of integrated external radiation doses to personnel.We have attempted to outline the types ofmeasurements needed; the accuracies required;the intrinsic limitations imposed by thesampling problem; and the capabilities and drawbacks of presently existing instrumentation.

We will summarize by reiterating severalpoints made in the main text:

a) The accuracy required of personneldosimetry systems is not excessively great:the ICRP (Ref. 1) has recommended maximum uncertainties of less than 50% (or less than 1rem, whichever is greater) in assessment ofannual dose equivalent.

b) One key requirement of any dosimetrysystem is to make sure that no. significantcomponent of the radiation field goes compretely unmeasured: in cases of large accidental exposure, such an omission would beregrettable indeed.

c) For routine monitoring of externalbeta/gamma radiations, adequate instrumentation exists today. While improvements are

definitely possible (and in some cases imminent,or at least probable from the current researchprogram in dosimetry), the basic task of beta/gamma dosimetry is now being performedreasonably well.

e) There is still need for a dosimeteruseful in those situations dominated by x-raysbelow about 15 keV.

f) Thermal-neutron dosimetry can now beperformed adequately with any of several dosimetry systems.

g) Fast-neutron dosimetry has largelyrelied for more than a decade upon the nucleartrack-emulsion technique, which suffers fromseveral important drawbacks. Research on anumber of possible alternate systems ought tobe encouraged.

h) Intermediate-enerft neutrons (-0.5 eVto -200 keV) are still a d~ficult measurementproblem. Albedo dosimeters are not now sufficiently well understood to allow their use inneutron fields with unknown energy spectra, andno other systems now seem capable of performingthis task adequately.

i) More work is required to develop asimpler way of assessing the energy spectraof external radiation fields, to complement themeasurement of dose-e~uivalent. For cases ofaccidental exposure t is is particularlyimportant, and has not (in our opinion) beengiven sufficient attention.

8 • ACKNOWLEDGMENT

For this section we particularly acknowledge thegenerous advice and review of:

George W. Campbell, Lawrence Livermore LaboratoryRichard C. McCall, Stanford Linear Accelerator CenterGeorge A. Morton, Lawrence Berkeley LaboratoryH. Wade Patterson, Lawrence Berkeley LaboratoryBen G. Samardzich, Lawrence Livermore LaboratoryRalph H. Thomas, Lawrence Berkeley Laboratory

c)$- INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

:,.)

9. REFERENCES

•. I


1. ICRP Publ. 12, "General Principles of Monitoring for Radiation Protection of Workers,"published for International Commission on Radiological Protection by Pergamon Press, Oxford(1968) •

2. M. Ehrlich, "The Use of Film Badges for Personnel Monitoring," lAEA Safety Series No.8,International Atomic Energy Agency, Vienna (1962).

3.

4.

5.

6.

7.

8.

\;

9.

10.

11.

12.

13.

"The Basic Requirements for Personnel Monitoring," lAEA Safety Series No. 14, InternationalAtomic Energy Agency, Vienna (1965).

D.E. Barber, "Standards of Performance for Film Badge Services," PHS Publication 99-RH-20,Environmental Health Series, USDHEW, Public Health Service, Washington, DC (1966).

K. Becker, Photoraphic Film Dosimetry, The Focal Press, London and New York, 1961 (in German),1966 (in Englis~.

A. Brodsky, A. Spritzer, F. Feagin, F. Bradley, G. Karches, and H. Mandelberg, "Accuracy andSensitiVity of Film Measurements of Gamma Radiation - Park IV, Intrinsic and ExtrinsicErrors," Health Physics 11, 1071 (1965).

H. Stewart, N. Modine, and J. Rolofson, "Low Energy Calibration of Film Used in Measuring X-raysfrom Color Television Receivers," p. 185 of "Conference on Detection and Measurement of XRadiation from Color Television Receivers, 28 March 1968," Proceedings published by U.S. PublicHealth Service, Bureau of Radiological Health, Rockville, MD 20852 (1968).

R. Kathren and A. Brodsky, " Accuracy and Sensitivity of Film Measurements of Gamma Radiation Part III, Effects of Humidity and Temperature During Gamma Irradiation," Health Physics 9,769 (1963). -

E. Storm and S. Shlaer, "Development of Energy-Independent Film Badges with Multi-ElementFilters," Health Physics 11, 1127 (1965).

J.R. Cameron, N. Suntharalingam, and G.N. Kenney, Thermoluminescent Dosimetry, University ofWisconsin Press, Madison (1968).

F.M. Lin and J.R. Cameron, "A Bibliography of Thermoluminescent Dosimetry," Health Physics 14,495 (1968). -

Luminescence Dosimetr¥, Proceedings of an International Conference at Stanford, June 21-23, 1965,F.R. Attix (ed.), avaIlable as CONF-650637, U.S. Atomic Energy Commission, Division of TechnicalInformation, Oak Ridge, TN 37830 (1967).

14. Third International Conference on Luminescence Dosimet ,Rise, Denmark, Rise Report No. 2491971. Available rom Danish Atomic Energy CommIssion, Rise, DK-4000, Roskilde, Denmark.

15. J. Cusimano and F. Cipperley, "Personnel Dosimetry Using Thermoluminescent Dosimeters," HealthPhysics!!, 339 (1968).

16. W.V. Baumgartner, "Capabilities and Methods to Measure X-Ray Radiation Originating in TVReceivers," p. 265 of "Conference on Detection and Measurement of X-Radiation from ColorTelevision Receivers, 28 March 1968," Procpedings published by U.S. Public Health Service,Bureau of Radiological Health, Rockville, ~ID 20852 (1968).

17. J.C. Hart, "Legal and Administrative Aspects of Personnel Dosimetry," Symposium on the Futureof Personnel Dosimetry, Annual Meeting of the Health Physics Society, New York, July 1971.Referred to by F.H. Attix in "A Current Look at TLD in Personnel Monitoring," Health Physics~, 287 (1972).

18. B.L. Rich and B.G. Samardzich, "Organizational Aspects of a Personnel Dosimetry Service,'iReport UCRL-73254, Lawrence Livermore Laboratory, Livermore, CA 94550. Health Physics (tobe published, 1972).

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING


19. T. Yamashita, N. Nada, H. Onishi, and S. Kitamura, "Calcium Sulfate Activated by Thuliumor Dysprosium for Thennoluminescence Dosimetry," Health Physics ~' 295 (1971).

20. 1. Bernstein, B. Bjarngard, and D. Jones, "On the Use of Phosphor-Teflon TLD's in HealthPhysics," Health Physics 14, 33 (1968).

21. D. Zirrnnennan, C. Rhyner, and J. Cameron, "Thennal Annealing Effects on the Thennoluminescenceof LiF," Health Physics 12, 525 (1966).

22. ANSI Standard N13.5, "Perfonnance Specifications for Direct Reading and Indirect ReadingPocket Dosimeters for X- and Gamma Radiation," American National Standards Institute, 1430Broadway, New York, NY 10018 (1972).

23. J. Cameron, "Radiophotoluminescent and Thennoluminescent Dosimetry," article in Manual onRadiation Dosimetry, N.W. Holm and R.J. Berry (ed.), Marcel Dekker, New York (1970).

24. K. Becker, "Recent Progress in Radiophotoluminescence Dosimetry," Health Physics 14,17 (1968).

25. Radiation Dose Measurements, Proceedings of an ENEA/OECD Conference in Stockholm, 12 June 1967,Eurppean Nuclear Energy Agency/Organization for Economic Cooperation and Development, Paris (1967).

26. R. Yokota, 1. Miyanaga, R. Maruyama, and Y. Nishiwaki, "The Basic Principles and the Role ofGlass Dosimeters in Personnel Dosimetry," P. 87 of Ref. 25.

27. K. Becker, "Radiophotoluminescence Dosimetry - A Bibliography," Health Physics g, 1367 (1966).

28. J.R. Harvey, W.H.R. Rudd, and S. Townsend, "A Personal Dosimeter Which Measures Dose fromThermal and Intennediate Energy Neutrons and from Gamma and Beta Radiation," Report RD/B/N1547,Central Electricity Generating Board, Berkeley Nuclear Laboratories, Berkeley, United Kingdom(1969), unpublished.

29. K. Becker, Atomic Energy Review~, I, 173, International Atomic Energy Agency, Vienna (1970).

30. K. Becker, J.S. Cheka, K.W. Crase, and R.B. Gammage, "New Exoelectron Dosimeters," p. 25 inAdvances in Ph,sical and Biological Radiation Detectors, Proceedings of a Symposium in Vienna,23 November 19 0, International Atomic Energy Agency, Vienna (1971).

31. J. Baarli and J. Dutrannois, "Purpose and Interpretation of Personnel Monitoring Data for HighEnergy Accelerators," p. 275 of Ref. 25.

32. R.L. Lehman, "Energy Response and Physical Properties of NTA Personnel Neutron DosimeterTrack Film," Report UCRL-95l3, Lawrence Berkeley Laboratory, Berkeley, CA 94720 (1961),unpublished.

33. J. Cheka, "Fast Neutron Film Dosimeter," Physical Review 90, 353 (1953); also, J. Cheka,"Recent Developments in Film Monitoring of Fast Neutrons,Ti'"'}fucleonics 12, 40 (1954).

34. P.S. Nagarajan, "Neutron Personnel Monitors Currently in Use," p. 103 in Radiation ProtectionMonitoring, Proceedings of Joint WHO-IAEA Regional Seminar in Bombay, 9 December 1968,International Atomic Energy Agency, Vienna (1969).

35. A. Gavallini, "Role, Interpretation, and Accuracy of Measurement of Fast Neutrons by Meansof Photographic Emulsions," p. 293 of Ref. 25.

36. T.O. Marshall and G.R. Stevenson, "Edge Effects in the Scanning of Nuclear-Track Emulsions forNeutron Dose Assessment," p. 549 in Neutron Monitoring, Proceedings of an IAEA Symposiumin Vienna, 29 August 1966, International Atomic Energy Agency, Vienna (1967).

37. M. Oshino, "Response of NTA Personnel Neutron Monitoring Film Worn on Human Phantom," LawrenceBerkeley Laboratory Report LBL-342, Health Physics (to be published, 1972).

38. K. Becker, "Dosimeter Applications of Track Etching," in Progress in Radiation Dosimetry,F. Attix (ed.), in preparation.

39. C. Unruh, W. Baumgartner, L. Kocher, L. Brackenbush, and G. Endres, "Personnel Neutron Dosimeter Developments," p. 433 in Neutron Monitoring, Proceedings of an IAEA Symposium in Vienna,29 August 1966, International Atomlc Energy Agency, Vienna (1967).

!.}

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING


40. C.O. Widell, "Neutron Dosimetry by the Fission-Fragment Method," p. 417 in Neutron Monitoring,Proceedings of an lAEA Sympositnn in Vienna, 29 August 1966, International Atomic EnergyAgency, Vienna (1967).

41. D.E. Hankins, "Factors Affecting the Design of Albedo-Neutron Dosimeters Containing LithitnnFluoride Thermo1tnninescent Dosimeters," Report LA-4832, Los Alamos Scientific Laboratory,Los Alamos, NM 87544 (1972), unpublished.

42. J.E. Hoy, "An Albedo-Type Personnel Dosimeter," Health Physics 23, 385 (1972). And also:J .E. Hoy, "Personnel Albedo Neutron Dosimeter with Thermo1tnninescent 6LiF and 7LiF," ReportDP-1277, Savannah River Laboratory, Aiken, SC 29801 (1972), unpublished.

43. B.E. Bjarngard and D. Jones, "A New Technique for Finger and Hand Dosimetry Using Solid TLDLiF-Teflon Dosimeters," Health Physics Society Annual Meeting, Houston, 29 June 1966(unpublished). Address: Controls for Radiation, Inc. Cambridge, MA 02139.

44. ToF. Johns, ''Use of Energy-Independent Dosimeters for Measuring Partial and Whole-Body Doses,"p. 241 of Ref. 25.

45. A. Knight (private communication, 1972). Address: National Radiological Protection Board,Clifton Avenue, Belmont Sutton, Surrey, United Kingdom.

tJ ,)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

.j

Exposure Rate Meter

Capintec Model 192

RAD-DOSGannna, X-RayCapintecJan. 1973

Class Dosimeter System



Performance

Requirements

Features

References

Cost

Address

Thimble-type ionization chambers and electrometer electronic system.Direct reading digital output in mR, R. mRlminute. R/minute.

20 mR (mR/min) full scale, to 2000 R (R/min) full scale

Temperature stability ±O.l% per °C

Power: 117 V ac, 50/60 Hz, 10 W

1. Calibrate X-ray diagnostic machines.2. Calibrate X-ray/cobalt-60 therapy machines.3. X-ray head leakage checks.4. Scattered radiation surveys.5. Intracavitary measurements.


Model 192 System: $1750.Special Purpose Probes: $500. each

Capintec Inc.63 East Sandford BoulevardMount Vernon, NY 10550(914) 664-6600

..l..,/ !~)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAn-DOSGannna, X-RayCapintecJan. 1973

Personnel Dosimeter

Capintec SEQ-5, 6, 7 and ChargerSEQ·6 SPECTRAL RESPONSE

• "'1I "'"

I I141·C• i1l

e 1 7 .oleo

l'G.

10 2 345 10' 2 345 103 2.ponse to energy considered Photon energy

c b

"'""V 1 I

V 141 Ce i1le 1 7 .oleo

//71 G•

10 2 345 10' 2 345 103

2~

esponse to the energy concerned Photon energyes onse to Co 60

R

R P

,8

,6,.,2

Teflon carbon ham er response

equivalent with 300mg/cm 2 50ft

human tissue

SEQ-5 SPECTRAL RESPONSE

,8

,6

,4

,2

1

,6

Res

,2

o

t

,6,.,2

1

o

Class Portable Dosimeter


Tissue-equivalent ionization chambers, with charging system.Direct-reading output in rad.

Sensitivityand Range Model Number

SEQ-5

SEQ-6SEQ-7

Sensitivities(Full Scale, in Rad)

0.2, 0.5, 2.0

0.2, 0.5, 2.00.5, 0.6

Effective WallThickness (mg/cm2)

300

3307 or 300

Sampling Continuous

Performance Temperature: Range: -20°C to +60oC

Requirements Charger Power: 1.5 V batterySize: Dosimeter Sizes: Pen-sized

Features 1. Charger has a "press-to-charge" system to increase battery life.2. Dosimeters have tissue-equivalent walls.3. Dosimeters are direct-reading.4. Low energy response: is flat down to 10 keV.

Cost Charger: $55. Dosimeters: $75. to $175.

Address Capintec Inc.63 East Sandford BoulevardMt. Vernon, NY 10550(914) 664-6600

'.J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

i..-J

TLO Dosimetry Service

Eberline

~ ~0.187"

RAD-DOSDosimetry ServiceEberlineJuly 1973

LOCKING DEVICE

O-RING SEAL

DECAL AND SARAN

TLD 8EHIND 10 mg/cm2

O·RINGSEAL

ALUMINUM FILTER

TLD BEHIND 286 mg/cm2

EXTRA CAVITYBEHIND 286 mg/cm2

Class


Thermoluminescent Dosimetry Service (TLO)

TLD dosimeters with various parameters are supplied, returned for processing, read out, and results reported. Read out is by heating and observingthermoluminescence.


Exposure, mrem: 5Standard Deviation:. 20%

1010%

504%

3004%

3,0004%

30,0004%

Features (1)

(2)(3)(4)(5)

Badge has two TLO chips, behind 10 and 285 mg/cm2, to enable calcula

tion of beta or non-penetrating x-ray dose.Dosimeter contains natural lithium.Wrist, ankle, ring badges also available.Environmental badges (5 LiF chips) available in weatherproof bag.Quarterly exchange is typical. Other cycles available.

References

Cost

Address


$1.50 per exchange

Eberline Instrument CorporationP.O. Box 2108Santa Fe, NM 87501(505) 982-1881

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Labor~tory

t..i i.l

<.1 UI

TLD Reader

Eberline TLR-5

RAD~DOS

TLD ReaderEberline 2July 1973

Pr~nciple ofOperation Thennoltuninescent Dosimeter (TLD) Reader

Each TLD requires 6 to 60 second cycle

Power: 117 Vac, 50/60 Hz, 120 WSize: 12" x 10" x 18" (30 x 25 x 45 em)Weight: 36 lb (16 kg)

(1) 5-digit display.(2) Glow curve signal available on rear banana jacks, 0 to 10 mY.(3) Background less than one count plus 10 mR, referred to 35 mg LiP.(4) Gas flowmeter available as option.(5) All solid-state circuitry.


Sampling

Requirements

Features

1 mR to 105 R in two ranges: 1 mR to 100 R1 R to 105 R

References

Cost

Address


$2300

Eberline Instrtunent CorporationP.O. Box 2108Santa Fe, NM 87501(505) 982-1881

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

"··-'-1

TLD Dosimeter ReaderE.G. &G. 8506B

RAD-DOSGammaE.G. &G.Mar. 1972

u



Sampling

Performance

Requirements

Features

Cost

Address

Accepts a TLD (thermoluminescent detector) in a light-tight chamber,heats it up with a regulated current, samples the glow curve peak,digital electronic display

Energy Sensitivity: See tables for TLD'sRange: 0.1 R to 18 KR

Peak of glow curve

Accuracy: ± 2% or 0.1 R whichever is greaterRead out time: < 20 secTemperature range: -10°C to 40°CHumidity Range: 0-70%

Power: 115 V ac, 50-60 Hz, 1ASize: 13 em, 28 em, 40 cm (5", 11", 17")Weight: 11.2 Kg (25 lbs)

Digital presentation

$2950

E.G.& G. Inc.Electronic Product Division35 Congress StreetSalem, Mass. 01970(617) 745-3200

I;

h.J '.) '-;.j r..~j >+) b'.) )

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSGarrnnaE.G. & G.Dec. 1971

Dosimeter System

E.G. &G. Model 2005A System

MODEL 2015A TlD READOUT

--I I:;c~l

PRINTER I I (X/~~~'~~~~~ER) l=::e=:=-:t.JI I DIGITAL

__ ---I L __ ---.J SIGNAL

CONTROLSIGNALS

DARK

~~:~ENT(;::=======~!:::=====~COMP.

PMT HIGH VOLTAGE

MODEL 2020A TLD READ HEAD

MODEL 2010A SYSTEM PROGRAMMER

Class Lab


The system comprises a model 2020A Read head,a model 20l0A Programmer, and a model 20l5A Readout. TheRead head is capable of housing, heating, and collectinglight from a TLD, the programmer allows the operator tocontrol the heat/time functions, and the readout is adigital, peak current reading pico-ammeter.


Sampling

Energy Sensitivity:Range:

Peak of the glow curve

See Tables fgr TLD's0.5 mR to 10 mR

Performance Accuracy:Temperature:Readout time:Relative humidity:

+0.05% to +12% for the model 20l5A25°C + 5°/iit

0-50%

Requirements Model 2020A 20l0A 20l5A

Power:

Size:

Weight:

From 2010

8"W,11.5"L6"D

117V ac. 60Hz.15° W max17 "W, 1 7" D, 5 . 3"H

117V ac, 60Hz

1 7"W, 1 7"D ,3.5"H20 lbs.

G.Dec. 1971

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSGannnaE.G. &page 2

.~J

Features

Cost

Address

Optional printer, stripchart recorder, or X-Y plotter

EG &G Inc.Electro-Optics Division35 Congress StreetSalem, Mass., 01970(617) 745-3200

liF DOSIMETERSDose Ran~e Fast Thermal

Neutron Neutron Repro-Dose Rate Response Response ducibilltr Re· figure

~oSDhorConflt:· Model Model Model Dependence PoB. ~6r,~~:s

for sponse Refer·Mode' uratlon 200SA Tl·3B 85060 R/sec R/n/em' Linearit, Dosimeter Curve en~e Size

ll·021 liF Mini 10mR' 10mR· ?OOI11R· Negligible - 2X 10-" 4.8 X 10-' 5% over the ±3% >IR B I a-12mm10'R 10'R 10'R to total dose ±20% at b-1.4mmNonlinear Nonlinear Nonlinear 10' range to 10mR>IO'R >IO'R . ·IO'R 10'R

TL·021·A liF '12 Mini 15mR· 10nlR· 2R· Negligible - 2 X 10'" 4.8 x 10" 5% over the ±3% >IR 8 2 a-6mm10'R 10'R 10'R to total dose ±20% at b-1.4mmNonlinear Nonlinear Nonlinear 10' range to 10mR>IO'R >IO'R >IO'R 10'R

TL·028·A liF Hot Press 10mR· 10mR· 200mR· Negligible - 2 x10'" 4.8 x10" 5% over the ±3% >IR B 3 a-b-V. inchChip 10'R 10'R 10'R to total dose ±20% at c- 0.030 inch

Nonlinear Nonlinear Nonlinear 10' range to 10mR>IO'R >IO'R >IO'R 10'R

TL·029 liF Micro 250mR· IR·IO'R N/A Negligible - 2x 10'" 4.8 x10" 7% over the ±6%or B 5 a-6mm10'R Nonlinear to total dose 0.2R b-0.9mmNonlinear >IO'R 10' range to>IO'R 10'R

TL·203 liF Square 5mR· 10mR· 200mR· <10%·10" - 2 x10'" 4.8 x 10" 5% over the ±3% >IR B 7 a-b-ImmRod 10'R IO'R 10'R total dose ±20% at c-6.0mm

Nonlinear Nonlinear Nonlinear range to 5mR>IO'R >IO'R >IO'R 10'R

TL·022 'liF Mini 10mR· 10mR· 500mR. Negligible - 2 x10'" 7.0x 10" 5% over the ±3% >IR B I a-12mm10'R 10'R 10'R to total dose ±20% at b-1.4mmNonlinear Nonlinear Nonlinear 10' range to 10mR>IO'R >IO'R >IO'R IO'R

TL·022A 'liF '12 Mini 200mR· 20mR· 2R· Negligible - 2 x10'" 7.0 x10" 5% over the ±3% >IR B 2 a-6mm10'R IO'R IO'R to total dose ±20% at b-1.4mmNonlinear Nonlinear Nonlinear 10' range to 10mR>IO'R >IO'R >IO'R 10'R

TL-ll26 'UF Micro 300mR· IR· N/A Negligible - 2x 10'" 7.0 x10" 7% over the ±6% >IOR B 5 a-6mm10'R 10'R to total dose ±20% at b-0.9mmNonlinear Nonlinear 10' range to 500mR

I>IO'R >IO'R 10'RTL·028-B 'liF Hot Press 10mR 10mR N/A <10%·10" -2x 10'" 7.0 x10" 5% over the ±3% >IR B 3 a-b-'V. inch

Chip 10'R 10'R total dose ±20% at c- 0.030 inchNonlinear Nonlinear range to 10mR>IO'R >IO'R 10'R

TL·201 'liF Hot Press 10mR 10mR N/A <10%·10" - 2 x lo·,e 7.0 x10" 5% over the ±3% >IR B 3 a-b-ImmChip 10'R 10'R total dose ±20% at c-6mm

Nonlinear Nonlinear ran~e to 10mR>IO'R >IO'R 10'

TL-ll23 'liF Mini 5mR 10mR 200mR Negligible - 2 x10'" 9.0 X10'" 5% over the ±3% >IR B I a-12mm10'R 10'R 10'R to total dose ±20% at b-1.4mmNonlinear Nonlinear Nonlinear 10' range to 10mR>IO'R >IO'R, >IO'R 10'R

n-ll23-A 'liF Ih Mini 10mR 200mR 2R· Negligible - 2 x10'" ,9.0 X10'" 5% over the ±3% >lR B 2 a-6mm10'R 10'R 10'R to total dose ±20% at b-1.4mmNonlinear Nonlinear Nonlinear 10' range to 10mR>IO'R >IO'R >IO'R 10'R

TL-ll27 'liF Micro 300mR IR· N/A Negligible - 2 x10'" 9.0 X 10'" 7% over the ±5% >IR B 5 a-6mm10'R 10'R to total dose ±20% at b-0.9mmNonlinear Nonlinear Hr range to 10mR>IO'R >IO'R 10'R

n·028-C 'liF Hot Press 10mR 10mR N/A <10%·10" - 2 x10'" 9.0 X10'" 5% over the ±3% >IR B 3 a-b- 'AI inchChip 10'R 10'R total dose ±20% at c- 0.030 inch

Nonlinear Nonlinear ranle to 10mR>IO'R >IO'R 10'

Tl-ll28- 'liF Hot Press 10mR· 10mR· N/A <10%·10" -2x 10'" 9.0 x10'" 5% over the ±3% >IR B 3 a-b-I-l inchC-20 Chip 10'R 10'R lolal dose ±20% at c-0.020 Inch

Nonlinear Nonlinear ranie to 10mR>lO'R >IO'R 10'

n·202 'lIF Square 5mR· IOmR· 200mR· <10%.10" -2x 10'" 9.0 x 10'" 5% over the ±3% >IR B 7 a-b-ImmRod IO'R IO'R 10'R total dose ±20% It c-6mm

Nonlinear Nonlinear Nonlinear ranle to IOmR>1O'R >IO'R >IO'R 10'

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSGammaE.G. &G.page 3 Dec. 1971

CaF2:Mn DOSIMETERSDose Range 'ast TIIermal

Neutron Neutron Repro·Dose Rate Response Response duclbillt, Re· Fleur.

Model Tl Co.liI:· Mode' Model Model Dependence P.B. R/n/cm 2 ,., sponse Refer·Phospho, uratlon 2005A Tl·3B 8506B R/sec R/n/em' Cau Rids lInearlt, Dosimeter Curve once SizeTl·031 CaF"Mn Mini 3mR· 10mR· 200mR- Negligible 2.3 x 10'" 1.2 x 10'" 5% over ±3% >IR A I a-12mm

10'R 10'R IO'R to dose ±20% at b-1.4mm10' ran~e 10mR

Tl-D31-A CaF"Mn Y, Mini 5mR· 20mR· lR· Negligible 2.3 x 10'" 1.2 x10'" 5% over ±3% >IR A 2 a-6mm10'R 10'R 10'R to dose ±20% at b-1.4mm

10' range 10mRTl-033 CaF,:Mn Hot Press 2mR· 5mR- N/A <10%·10" 2.3 x10'" 1.2 x10-" 3%·IO'R ±2% >IR A 3 a-b-V8 inch

Chip 3 x10'R 3 x10'R 10%- ±20% at c-0.035 inch3 x10'R 20mR

Tl·035 CaF,:Mn Tube 0.5mR· 0.5mR· N/A <10%·10" 2.3 x10-" 1.2 x10'" 2% over ±2%or A 4 -IO'R IO'R dose 0.4mR

rangeTl·039 CaF,:Mn Micro loomR· IR-IO'R N/A Negligible 2.3 x 10'10 1.2 x 10'10 7% over ±3%or A 5 a-6mm

IO'R to dose O.IR b-0.9mm10' ran~e

Tl-D72 CaF"Mn Powder 0.2mR· NtA N/A <10%·10" 2.3 x 10'10 1.2 x 10'10 7%·IO'R ±15% >100 A 6 200-4003 x10'R mR mesh

±40% at10mR

Tl·301 CaF"Mn Square ImR· 5mR· 200mR· <10%·10" 2.3 x10'" 1.2 x10'10 3%·IO'R ±2% >IR A 7 I-b-ImmRod 3 x IO'R 3 xIO'R 10'R 10%· ±20% It c-6mm

3 x10'R 20rnR

CaF2 DOSIMETER TYPES

FIG.1 MINI FIG. 2 1/2 MINI FIG. 3 HOT PRESS CHIP

f lt !i It~. _J

FIG. 4 TUBE

r.;··-'~;.

\ ".": ~rt "'-1"-!I',i

HI,..

f)

.!ft,'\.~

FIG. 5 MICRO FIG. 6 POWDER FIG. 1 SQUARE ROD

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-OOSGannnaE.G. &G.page 4 Dec. 1971

EFFECTIVE ENERGY RESPONSE CURVES

III 10.0~ 8.0~ 6.0III

~ 4.0III>~ 2.0..JIII

II:: 1.0.

10 20 30 ~o 70 100 200 300' 1000EFFECTIVE ENERGY, k.V

A. Effective Energy Response Curve.

1.4wIIIZ0IL

1.2IIIwII:w>

~1.0

IIIII:

0.8

--- .......................

""""'-~

10 20 30 ~o 70 100 200 300 1000EFFECTIVE ENERGY, keV

B. Effective Energy Response Curve.

--r.

III 1.0IIIz 0.80IL 0.6IIIIIIII:: 0.4III>j:OIl

0.2..JIIIII::

0.110 10 2 10 3

EFFECTIVE ENERGY, k.V

C. Effective Energy Response Curve.

1.0III 0.8z~ 0.6III

~ 0.4

III>~ 0.2..JIIIIt

0.110 102

EFFECTIVE ENERGY, keVD. Effective Energy Response Curve.

10 3

- j,,--j

- ~

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

'--J

RAD-DOSGammaE.G. & G.page 5 Dec. 1971

LiF DOSIMETER TYPES

FIG.1 MINI FI6.2 1/2 MINI FIG. 3 HOT PRESS CHIP

FIG. 5 MICRO

SHIELDS

FIG. 1 SQUARE ROD .LIF-GREENLIF-BLUE

'LIF-ROSE

FIG.8 MINI FIG.9 TUBE FIG.10 HOT PRESS CHIP FI G.11 MIN I(HOLDS 3 DOSIMETERS)

FIG.12 MICROAND 1/2 MINI

FIG. 13 EQUILIBRIUM FIG.14 ELECTRONSHIELD FOR MINIS EQUILIBRIUM SHIELD

(HOLDS ALL MINIS AND MICROS)

G.Dec. 1971

-$ INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

DOSIMETER/SHIELD COMBINATIONS

RAD-DOSGannnaE.G. &page 6

Dose Range F••t ThermllNeutr.. Neutron Repro-

Dose Rtte R..' .... Response ducibllltr R.· FlEur.n Conlltl· Mode' Model Model Dependence:/~i.III' ~~~,~~;. for sponse Refer· Shleld/

Mod•• PMs,hor uf.tlon 200SA TL·3B 1506B R/.ec L1nearll, Dosimeter Curv. enee DosimeterTl.()11 CaF"Mn, Mini 3mR· IOmR· 200mR· Negligible - - 5% over ±3% >IR C 8 TL·051,

Shield 10'R 10'R IO'R to dose range ±20% at TL·03110' IOmR

n'()Il·A CaF,:Mn, '12 Mini 5mR· 20mR· IR· Negligible - - 5% over ±3% >IR C 12 TL·059,Shield 10'R 10'R 10'R to dose range ±20% at TL·031·A

10' 10mRn·013 CaF,:Mn, Hot Press 2mR· 5mR· N/A <10%·10" - - 3%·IO'R ±2% >IR C 10 TL·053,

Shield Chip 3 x10'R 3 x10'R 10%· ±20% at TL·0333 x10'R 20mR

TL·014 CaF,:Mn, Square ImR· 5mR· 200mR· <10%·10" - - 3%·IO'R ±2% >IR C 12 TL·059,Shield Rod 3 x10'R 3 x IO'R 10'R 10%· ±20% at TL·301

3 x10'R 20mRn·ols CaF,:Mn, Tube 0.5mR· O.5mR· N/A Negligible - - 2% over ±2% or D 9 TL·052,

Shield IO'R 10'R to dose range 0.4mR TL·03510"R/sec

Tl·OI9 CaF,:Mn, Micro 100mR· IR·IO'R N/A Negligible - - 7% over ±3% or C 12 TL·059,Shield 10'R to the total O.IR TL·039

10' dose range (3 each)TL.()20 CaF"Mn, Mini 3mR· 10mR· 200mR· Negligible - - 5% over ±3% >IR C 11 TL·055,

Shield IO'R 10'R lO'R to the total ±20% at TL.()3110' llose range IOmR (3 eachl

ACCESSORIES

MODEL TL -001TWO-COMPARTMENT DOSIMETERHOLDER (HOLDS ALL DOSIMETER

TYPES, EXCEPT TL-0351

MODEL TL-82-BREFERENCE LIGHT

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

TLD Dosimetry System

Harshaw Model 2271

RAD-DOSTLD SystemHarshawJuly 1973

12-

Class


Sensitivity

Sampling

Requirements

Features

Reference

Cost

Address

Laboratory

Thennoluminescent Dosimetry (TLD) system. TLD chips are read out by heatingwhich generates luminescence, detected by a phototube. System is automated.TLD chips are lithium fluoride (LiF).

TLD dose from 10 mR to 10,000 R

TLD card containing 2 chips can be read out in 40 seconds

Power:Size:Weight:

(1) System can acconnnodate 250 TLD cards (2 chips each) automatically.(2) BCD identification of each card also automated.(3) Manual mode also available.(4) TLD reader, integrating picoannneter, flow regulator, flow meter, tele

typewriter all included.

(1) Manufacturer's specifications

$

Harshaw Chemical Company6801 Cochran RoadSolon, OH 44139(216) 248-7400

n

Class

uINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Film TLD Dosimetry Service

lCN Inc.

Film, TLD Dosimetry Service

RAD-DOSDosimetry ServiceICNAug. 1972



Film, TLD, or both distributed to user, developed after exposure, resultsof analysis reported to user.

Film Sensitivity: 5 mrem (soft X-rays), 10-20 mrem (gamma), 30 mrem (beta)TLD Sensitivity: 10 mrad to 100,000 radFilm Energy Range: 20 keV to several MeV for gammasTLD Energy Range: ±15%, 20 keV to 1.3 MeV for gammas

Performance Film Accuracy:TLD Accuracy:

15-25%±20% at 10 mrad, ±5% above 1 rad

Features

References

1. Dosimeters cycle weekly, biweekly, or monthly2. Reports mailed to user within 48 hours of receipt of dosimeter3. Film dosimeter has a backup film for use in case of accidental damage4. Finger-ring and wrist badge dosimeters also available


Cost Units 13, y, X Film

1 $1. 75

2 1.10

3 .85

4-5 .75

Ring Badge

$1.75

1.50

1. 20

1.10

TLDTLD and Film

$2.50 $3.75

2.00 2.75

1.60 2.00

1.40 1.80

Address ICN Tracer1ab26201 Miles RoadCleveland, OH 44128(216) 662-0218

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSBeta, Gamma, X-rayJohnsonDec. 1971

Dosimeter Charger-Reader

Johnson Model L-60

Class



Portable

Ion chamber charger-reader

Pocket Chambers

Sampling

Performance

ModelL-65L-69L-70L-8l

Continuous

Stability

Range200 mr200 mrem200 mrem

2 r

Type of RadiationX, gammaX, gamma, thermal neutronsthermal neutrons onlyX, gamma

Requirements

Features

Cost

Address

Power: One "D" cell and six 22.5 V No. 412 Minimax batteriesDosimeter size: 1.3 em D, 4 em or 9 em L (0.5" D, 1.5" or 3.5" L)Weight:

Chambers are hermetically sealed. Sleeves are included to provideelectron equilibrium at higher energies.

$150

William B. Johnson and AssociatesResearch ParkBoonton AvenueMontville, New Jersey 07045(201) 334-9221

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Personnel Dosimetry Service

Landauer

RAD-DOSX, GAMLandauerOct. 1972

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Personnel Dosimetry Service

RAD-DOSX,GAMLandauerPage 2 Oct. 1972



Performance

Features

References

LiF (TLD) dosimeters, readout by Landauer after mail-exchange

Sensitivity: Exposure range 10 mR to 100,000 REnergy Range: Energy independent above 100 keV, 40% duration down to

18 keV

Accuracy: Standard error <25% (10 mR), <10% (>100 mR)

1. Weekly, biweekly, monthly schedules.2. Dosimeters can be furnished sealed in sterile tubing.3. TLD ring dosimeter service also available.

'Manufacturer's specifications

Cost

Address

Number of Five-Dosimeter Kits1-5

6-1011-2526-50

51-100over 100

R.S. Landauer Jr. &Co.Glenwood Science ParkGlenwood, IL 60425(312) 755-7000

Price Per Kit$25.0021.5017.5015.0012.50

on quote

I-~-

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Thermal Neutron Dosimeter

Nuclear Associates Model 06-609

RAD-DOSNeutronsNuclear Associates Inc.Oct. 1972

~-

Class



Sampling

Performance

Requirements

References

Cost

Address

Portable, Fountain Pen Size

Boron-coated ion chamber measured first-collision thermal neutron dose ina gamma field, reads in mrem.

Energy Sensitivity: Thermal __Calibration: 670 thermal neutrons cm 2sec 1 120 mrem for 40 hrExposure Range: 0-120 mrem

Continuous

Accuracy: ±10% of true dosage

Power: Use chargerSize: Four inches x 9/16 in. diameterWeight: Two ounces


$130.

Nuclear Associates35 Urban AvenueWestbury, NY 11590(516) 333-9344

-~¥

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Direct Reading Dosimeters

Nuclear Associates Inc.

RAD-DOSGamma, X-RayNuclear Associates Inc.Oct. 1972

Class Portable, Pocket, fountain Pen Size

Principle ofOperation A quartz fiber electrometer, compound microscope calibrated readout.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSGannna, X-RayNuclear AssociatesPage 2 Oct. 1972

Energy Sensitivity:Sensitivityand Range

Model RangeCost1-9 ea.

Sampling

Performance

Requirements

Features

References

Cost

Address

06-862 200 mr $45.00883 500 mr 55.00866 1 r 60.00608 10 r 67.50619 100 r 75.00638 200 r 75.00686 600 r 75.00

Continuous

Accuracy: ±10% of doseLeakage: 2% per 24 hours

Power: Use chargerSize: 4" L x 9/16" DWeight: About 2 ounces

Optional Charger, Model 06-906, $55.00Optional Calibrator, Model 06-200, $37.50


See chart above

Nuclear Associates Inc.35 Urhan AvenueWestbury, NY 11590(516) 333-9344

.- ~

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSX-RayNuclear Associates Inc.Oct. 1972

X-Ray Dosimeter

Nuclear Associates Model 06-002, 050, 099

Low EnergyDirect Reading

Dosimeter

FRAME ----FIBER

FIGURE 4. ION CHAMBER

FIGURE 5.

FRAMEFIBER

FIGURE 3, ION CHAMBER

CENTER OFSENSITIVE

/3" VOLUME~'I6~ARTZ GLASS SCALE

ICONDTNSER FRAME! FIBER CLIP

"",,, " ." II ~...~~~~~"", ~ V

CHARGING-~LAT:~~'\:N CHAMBER

SWITCH ELECTROME~R~FIGURE 1. AIR VOLUME

Typical Spectral Response

200150100

ENERGY (KEY) -

5018 30

1.4

1.2

f 1.0

i 0.8

z'"'" 0.6

0,4

0.2

'-)

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Portable, Pocket

RAD-DOSX-RayNuclear Associates Inc.Page 2 Oct. 1972

Principleof Operation Plastic walls allow low energy X-rays to penetrate the ion chamber.


Sampling

Model

06-002050

099

Continuous

Range

0-200 mR0-5 R

0-100 R

Performance

Requirements

References

Cost

Address

Accuracy: ±15% of true dose for 30 keV X-rays±10% of 30 keV reading for 15 to 100 keV+20%/-10% of 30 keV reading for 30 to 225 keV

Leakage: 2% of full scale/24 hr

Power: Use chargerSize: Four in. length x 9/16 in. diameterWeight: About 2 oz


$75.

Nuclear Associates Inc.35 Urban AvenueWestbury, NY 11590(516) 333-9344

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

X-Ray Dosimeter

Nucleus Model 06-002, 050, 099(Bendix)

RAD-DOSX-rayNucleus, Inc.Mar. 1972

06-050Low-Energy Dosimeter

\;

Class



Sampling

Performance

Requirements

Cost

Address

Portable, pocket

Plastic walls allows low energy X-rays to penetrate theion chamber

Model Range

06-002 0-200 rnR050 0-5 R099 0-100 R

Continuous

Accuracy: ±15% of true dose for 30 keY x-rays±10% of 30 keY reading for 15 to 100 keY+20% -10% of 30 keY reading for 30 to 225 keY

Leakage 2% of full scale/24 hours

Power: use chargerSize: 4" in lengthWeight: about 2 ounces

$75

Nucleus, Inc.P.O. Box ROak Ridge, Tenn. 37830(615) 483-0008

.)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Thermal Neutron Dosimeter

Nucleus Model 06-609

RAD-OOSNeutronsNucleus Inc.Mar. 1972

Class



Sampling

Performance

Requirements

Features

Cost

Address

Portable, fountain pen size

Boron coated ion chamber measured first-collision thermal neutrondose in a gamma field, reads in rem.

Energy Sensitivity: thermalCalibration: 670 thermal neutrons!cm2!sec=120 mrem, for 40 hoursExposure range: 0-120 mrem

Continuous

Accuracy: Unavailable

Power: Use chargerSize: 4 inchesWeight: 2 ounces

$130

Nucleus Inc.P.O. Box ROak Ridge, Tenn. 37830(615) 483-0008

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

,-,

~.J ~;;)",1 ;i

-~.'j.~ ,~)

Direct Reading Dosimeter

Nucleus Model 06-884, 886

RAD-DOSGannna, NeutronNucleus, Inc.Mar. 1972

Class Portable, pocket



Sampling

Performance

Requirements

Features

Cost

Address

Tissue equivalent dosimeter, measures both fast neutron and gannnadose in rads, based on collisions between fast neutrons and atomsof soft tissue with the empirical formula CSH400l8N.

Neutron energies: 20 keV to 15 MeVExposure: 20 mrads to 600 radsGannna energies: 80 keV to 3 MeV

Continuous

Accuracy: 20% of actual dose for neutrons10% of actual dose for Cobalt-60 and Cesium-137 gannnas15% of actual dose for gannnas from 80 keV to 3 MeV

Leakage: Unavailable

Power: Use chargerSize: 4 inches, lengthWeight: 2 ounces

To measure the first-collision dose of fast neutrons, subtractthe neutron insensitive dosimeter reading (model 06-886, $115)from the tissue equivalent dosimeter reading

$130 each

Nucleus, Inc.P.O. Box ROak Ridge, Tenn. 37830(615) 483-0008

--I;;

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

T10 Personnel Dosimetry Readout System

Panasonic Model UD-sOZA

RAD-DOSX,GAMPanasonicAug. 1972

Class Laboratory T10 Dosimeter Readout System


Performance

Requirements

Features

References

Cost

Address

Precise heating by convection: hot flowing air passes over T10 dosimeter.T10 light output detected by photomultiplier tube, displayed on digitalreadout of area under T10 glow curve.

Accuracy: 0.2% of full scaleReadout Time: 6, 10, or 12 secondsDisplay: Four digit nixie-tube readout, automatic ranging

(0.001 mR to 199.9 R, 4 ranges)Calibration: Radioisotope light source

Power: AC 100/115 V, 200 WSize: 43 x 43 x 23 cm (16.9" x 16.9" x 8.9")Weight: 18 kg (40 lb)

BCD output connection for auxiliary printer; adaptable to many differentT10 geometrical shapes


Matsushita Electric Corporation of AmericaPan Am Building200 Park AvenueNew York, NY 10017

u ... ,INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSX, GAMPanasonicOct. 1972

Personnel Dosimeters

Panasonic TLD Dosimeters

CaSO..:Tm with shield (UD-220S

Energy (KeV)

0.5··L-_-,L--:l--'-~.LJ...LLI __.L--'-:--L.w....L.l:'-L_--,J--:-...L.L.I..J.-J...l..J:I10 20 30 50 100 200 300 500 1.000 2.000 5.000 10.000

..""

10~~mm1dJm11-- -·H-rlt1-

5 CaSO.. :Tm without shield UD-llOS)4:f--+-+-+-I--t-'h'fF"-'-"'F"'F---'Fi"-A"i-1'F--+-++-J+lf+H

~3f---+-+-+-t-1+H"c--+--l'--H-+++tt--+---t--t--+-HH+I

~. \,wl>...&1

Exposure (R)

ENERGY RESPONSE OF CaSO.: Tm DOSIMETERS; (UD-llOS. UD-200S) LINEARITY OF CaSO.: Tm

Standard deviation ±1.5%

1 I I

2.0

1.5lOOKeV

l"

1.0

~......

ti.0.5

20

Exposure lOOpR

Repeated cycles

Standard deviation ±30%

200"C'-'S'"'o.-,'=-m----------,UD-200S

2015

Exposure SmR

10

Repeated cycles

CaSO~:Tm

UD-200S

3(mR)

2

30KeV

REPEATED APPLICATION OF CaSO. :Tm DOSIMETER (UO-200S)o0'---'30---60'---00..L---'12-0--15O'----'180

Direction (degrees)

DIRECTIONAL RESPONSE OF CaSO.: Tm DOSIMETER (UD-200S)

,.130

, I.20

Exposure l00R±O.8"

Reading l00R::~:i:

Annealing 4OO'C 5 mineach cycle

Repeated cycle

, I,! 'I! ,

10 15

110

100

g

i90

~ 80

J10

(MeV)

200 300 500

(K,V)

10020 30 5010

I 111111i I I

~lD =~'''ti, "',,', ,_

(O.6mm thick)--1 /

I ..... 1--....

, J

7

1.0

O.

0.8

o

1.3

1.2

I.,1.4

ENERGY RESPONSE OF BeO (uD-170A. UD-170B)

REPRODUCIBILITY OF BeO TLD

---.CLINICAL DOSE---

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Personnel Dosimeters

RAD-DOSX, GAMPanasonicPage 2 Oct. 1972



Features

References

Thermoluminescent dosimeters (TLD) of CaS04:Tm and BeO

Energy FadingModel Dimensions Repro- with in 6

Number Phosphor Diam Length Range ducibility Shield Months

lID-200S CaS04:Tm Hnun 60 nun 0.1 mR 0.1 mR ±30% ±40% 8%to 20 R 5 mR ± 1% (>30 keV)

lID-HOS CaS04 :Tm 2 12 0.1 mR 0.1 mR ±30% ±20% 8%to 20 R 5 mR ± 1% (>200 keV)

lID-lOOM CaS04:Tm 10 0.06 10 mR 10 mR ±30% ±20% 8%to 100 mR ± 2% (>200 keV)

2000 R

lID-170A BeO 2.2 12 2 mR 2 mR ±30% ±25%to 100 mR ± 1% (>15 keV) 6%

200 R

lID-170B BeG 1.2 8 10 mR 10 mR ±30% ±25% 6%to 1 R ± 1% (>15 keV)

1000 R


Cost

Address

Readout Instruments

Model lID-505A

Dosimeter

Model lID-200SlID-HOSUD-IOOM-8UD-170AlID-170BlID-6l0FUD-6HFlID-6l2

Dosimeter Annealing Furnace

Model 602

[All prices F.O.B. Westwood, NJ]

Teledyne Isotopes50 Van Buren AvenueWestwood, NJ 07675(201) 664-7070 Telex 134-474

$4800.

21. 706.641.556.646.642.584.253.26

822.

~futsushita Electric Corporation of AmericaPan Am Building200 Park AvenueNew York, NY 10017

;" "-i ~ U \,;,,.,~! .<c' ~"'~

~j

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Pocket Dosimeter &Charger

Picker 655-010, 019

RAD-DOSGamma, Neutron, X-rayPicker NuclearOct. 1972

Typical appearance ofgraduated scale in 655-010Dosimeter (enlarged).

Class



Sampling

Pen size

Ionization chamber with built in microscope

MODEL PARTICLE ENERGY RANGE

655-010 Gamma, X 80 keV to 300 MeV 0-200 mR655-012 Neutrons 0.025 eV 0-120 m Rem

Continuous

Performance Accuracy:Leakage:

10% of true dose2% per day

Requirements Power: One 1.5 V battery for chargerSize: 11 em L, 1 em D (4.4"L, 0.5"D)Weight: 150 grams (1.25 oz)

Cost 655-010655-012655-019

$42$85$50-charger

Address Picker Corporation333 State StreetNorth Haven, CN 06473

Picker CorporationMarketin~ Services6119 Highland RoadCleveland, OHAttention: Mr. Frank Dean

J

IINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

TLD·Reader

Radiation Detection Mark IV Model 1100

RAD-DOSTLD ReaderRadiation DetectionAug. 1972

Class Laboratory



Perfonnance

Requirements

Features

References

Cost

Address

TLD reader for thennoluminescent dosimeters. Accepts a wide variety ofpowdered or solid TLD's, mainly designed for LiF. Constant voltage heatersupply, chopper stabilized operational amplifier.

Sensitivity: 10 mR to 50,000 R for LiF

Accuracy: 10 mR to 100 mR better than ±10 mR100 mR to 1 R better than ±10%Above 1 R better than ±5%

Readout Time: 10 to 15 seconds

Power: 115 VAC, 60 cyclesSize: 12.4" height, 14.1" width, 18.6" depth (31 x 36 x 47 cm)Weight: 42 lb (19 kg)

1. Removable planchet for powder samples2. Internal reference light3. Provision for recording glow curves4. Inert gas flow to suppress nonradiation-induced luminescence


$1595.

Radiation Detection Company162 Wolfe RoadSunnyvale, CA 94088(415) 967-2837

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

, RAD-DOSDosimetry ServiceRadiation DetectionOct. 1972

Film Badge Dosimetry Service

Radiation Detection Company I.oor---------------,

~",i_ 0.80

'lJg 0.60

I0.40

~!::'Ii~ 0.20

"'i"

O.'-::----''-:---'-,,----....L,--J..,-----l0.5 1.9 1.5 2.0 2.5 3.0

BETA RAY ENERG"f (MJ::V)

BETA RAY SENSITIVITY OF FRONT FILM IN R·D- FILM PACKET

BETA RAY SENSITIVITY OF FRONT FILMIN R·D FILM PACKET

EFFECTIVE ENERGY (KEY)

TYPICAL FILM DENSITIES UNDER R 0 BADGE FILTE~S FOR O.3R EXPOSURE

FILM DENSITIES UNDER R·D BADGEFILTERS FOR O.3R EXPOSURE

Class


Film Badge Dosimetry Service

Film is distributed to user, developed after exposure, exposure readingreported. Film is sensitive to gannna, X-ray, and beta radiation, withfour filters.


Radiation

X, Gannna

Beta

Energy Range25 keV to 70 keV70 keV to 3 MeV

Above 1 MeV

Exposure or Dose Equivalent0.005 to 50 R0.01 to 1000 R

0.01 to 1000 rem

Filters

Features

ReferencesCost

Address

Open Window Region0.125" Plastic0.032" Aluminum0.015" Cadmium plus Aluminum0.030" Lead plus AluminUlJl

1. Films cycle weekly, biweekly, monthly.2. Reports mailed to user within three days of receipt of film.3. Ring dosimeters also available.4. Neutron dosimeters using several activation foils also available.

Manufacturer's specificationsUpon request

Radiation Detection Company162 Wolfe RoadSunnyvale, CA 94086(408) 735-8700

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Dosimeter/Charger System

REM Incorporated

RAD-DOSBeta, Gamma, X-RayREMAug. 1972

Class Portable Dosimeter



Sampling

Perfonnance

Requirements

Features

References

Cost

Address

Quartz-fiber ion chamber, charger-reader system, output in rad

Sensitivity: Eight models with full-scale sensitivities of0.2, 5, 10, 20, SO, 100, 200, 600 rad; one neutronsensitive model

Energy Range: 15% maximum energy dependence, 80 keV to 2 MeV (gammas)

Continuous

Accuracy: ±10% for gammas, ±20% for neutrons

Power: 1.5 volt battery, lifetime a few hundred dosimeter chargesKit Size: 6" x 8" x 3" (IS em x 20 em x 7.5 em)Kit Weight: 2 lb (1 kg)Dosimeter Size: 4-1/2" length, 1/2" diameterDosimeter Weight: 1/2 oz (14 g)

Leakage 2%/24 hours; geotropism ±2%; hermetically sealed chamber


$65.

REM Incorporated2000 Colorado AvenueSanta Monica, CA 90404(213) 828-6078

, ,h-J i.) 'i,-)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Pocket Dosimeter

REM Squeeler Model 122

RAD-OOSX-Ray, GanunaREM, Inc.Nov. 1972

,,=)

Class



Sampling

Performance

Requirements

References

Cost

Address

Personal, Portable

Air equivalent ionization chamber measures the integrated dose,audible alarm at preselected adjustable dose.

Energy Response: ± 15% 25 KeV to 50 KeV± 10% 50 KeV to 2 MeV

Range: Model l22A 20-300 mR alarm level settingsModel l22B 200 mR to 3 R alarm level settings

Continuous

Accuracy: ± 5%Leakage: Less than 3 mR per 8 hours

Power: Two 22.5 V batteries, 100 hoursSize: 6.5 em, 15 cm, 2.5 em (2.5", 6", 1")Weight:


REM Incorporated3107 Pico BoulevardSanta Monica, CA 90405(213) 828-6469

'~J .)INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Dosimeters

Searle Analytic Models NC-40l, 402, 405

RAD-DOSGAM, XRA, NEDSearle, Nuclear ChicagoJuly 1973

Class


Portable, personnel dosimeter

Model 401, 402, indirect reading quartz fiber volt meterModel 405, indirect reading ion chamber

Model: 401 402 405

Sensitivity

Performance

Requirements

References

Radiation Thermal Gamma GammaMeasured: Neutrons x-ray' x-rayFull-scaleRange: 120 mrem 200 mr 200 mr

Accuracy: ±10% ±10%_.Average leakage Less than 1% Less than 1%per 24 hours: of full scale of full scale

Power: Battery, 1. 5 v Battery, 1.5 v Chargerrequired

Size: 1.5 em dia. 1. 5 em dia. 1.3 em dia.10.5 em long 10.5 em long 9 em long

Weight: 45 g (1. 25 oz) 45 g (1. 25 oz) 3D g (1 oz)


Cost

Address

Dosimeter Model No. 401402405

Charger Model No. 403404

Searle Analytic, Inc.(formerly Nuclear-Chicago)2000 Nuclear DriveDes Plaines, Illinois 60018(312) 827-4456

$$$$$

!- ~

•.....-i !,,)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSGanuna, X-Ray, NeutronTeledyne IsotopesJuly 1973

TLD Dosimetry System and Badge Service

Teledyne Radi-Guard and Model 8300

I

10 I I-1--- ----

20 1 2I.... _-----I

301 3-~----401 4

I

ClU>

1ft

Gl

N

l")....Q

FILTER

OPEN WINDOW

FILTER

FILTER

Multi-area dosimeter.4 main readout areas(1,2,3, 4) and 4 backupareas (1 a, 2a, 3a, 4a).

Rear view of dosimeter wiihidentification numbers. 2dots insure dosimeter isproperly inserted in reader.

Standard personnelbadge filter array.

RADI-GUARD DOSIMETER

Model 8300 Reade!'

Class


Thennoluminescent Dosimetry System (TLD)

TLD dosimeters with various parameters are read out by heating and observingthermoluminescence. Badge service is provided. Standard Badge (see figure)has following filters:

1. 2 mm plastic + 1 mm AI2. open3. 1 mm plastic + 1 mm Cu + 1 mm Al4. 1 mm plastic + 1 nm Pb + 1 mm AI


(a)

(b)

PeTsonnelwith Cobalt-60 exposure, maximum error (90%) = ± 8 mR or ±l0%,whichever is greater. Dosimeter is 15% loaded LiF.

EnvironmentalStandard dosimeter is CaSO.. :Dy, 30% loaded.

Integrator linear to ±1.5% over entire range6-decade displayGlow curve output (0 to 8 volts) provided, with automatic rangechangingInert gas flow is usedBuilt-in annealing feature with on-off switchFast calibration (2 seconds)4 programmed temperature cycles available, cycle times 12 to 18 secSwitch can enable reading of LiF, Ca:SO.. :Dy, and finger dosimetersModel 9100 automatic system is compatible

(a) Model 8300 Reader(1)(2)(3)

(4)(5)(6)(7)(8)(9)

Features

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAn-DOSGamma, X-Ray, NeutronTeledyne IsotopesPage 2 July 1973

Features (Cont'd)

References

(b) TLD Dosimeters(1) Rods (1 mm diameter, 6 to 150 mm long) available in 6LiF, 7LiF,

CaS04:Mn, LizB407:Mn(2) Tape (25 mm wide, 0.4 mm thick) available in 7LiF(3) Discs of various sizes available in 7LiF, 6LiF, LizB407:~1n,

CaFz:Mn, CaS04:Mn

(c) Dosimetry Service(1) Issue period: 1, 2, 4 weeks, 1 month or 3 months(2) Radi-Guard dosimeters (see figure) are used(3) Calibration is done with cobalt-60(4) Zero control badges supplied free with each shipment

1) Manufacturer's specifications

Cost

Address

Model 8300 Reader

Dosimetry Service: processing per badgereport charge per reporting

periodreplacement for lost badgeinitial charge per badge

Dosimeters -- prices vary with particular models

Teledyne Isotopes50 Van Buren AvenueWestwood, NJ 07675(201) 664-7070

$

$ 0.65

$ 5.00$ 2.50$ 0.75

.}

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSPocketUKAEAAug. 1972

Gamma Dose-Rate Alann

uKAEA Model 0023

Oo..ratc In I\"h

I

2

... ------3. '

c 30 / I1_ 2. I

il 18 /' I0.1 \ I

1':(' !N '" 'if ltl

t 100 I- - - - - - - - - - - - - - - - - - - - - - - - - - --

I Ii :~~------------------------I

\

1:: ---------------------1 \

: Kl ---------~~~~~===~~=~- \ \ ~;\ ~------------- I I : I.. r------------ I I I II 5 I I I I I

• I I I I I3 I i I I I

I I I I I

: I I I :I I I II I I II I I II I I II I I 1I I I I II I I I II I I I II I I I I

I : I I I :I : I I I II I I I I I

2gHkg ~~h

\-'")

Pip rate against doserate

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Portable, Pocket

RAD-DOSPocketUKAEAPage 2 Aug. 1972

Miniature GM counter, energy compensating filter, audio oscillator,and speaker.



Performance

Energy Range:Sensitivity:

Accuracy:Temperature:

60 keV to 2 MeVo to 250 mR/hr, proportional; 250 to 2000 mR, nonlinear;2000 R/hr maximwn

Requirements

Features

References

Cost

Power: One 4 V mercury cell, Mallory TR133R; 6 monthsSize: 15 cm x 4.5 cm x 2.6 em (5.8" x 1.8" xLI")Weight: 140 g (0.3 lb)

Built in Sr-90 test source operated by push button, equivalent to2-4 mR/hr. Model 95/0061/6 has suppressed response below 120 mR/hr,no test source, threshold device.


$240.

Address Nuclear Enterprises Ltd.Bath Road, BeenhamReading, Berks, ENGLANDTel.: Woolhampton 2121

Nuclear Enterprises Ltd.935 Terminal WaySan Carlos, CA 94070(415) 593-1455

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Personal Dosimeter

Victoreen Model 541-A

RAD-DOSGammaVictoreen 3Mar. 1972

Class Portable



Performance

Requirements

Features

Cost

Remarks

Address

Pocket ion chamber

Energy Sensitivity: ± 10% from 55 keV to 2 MeV, gamma± 15% from 45 keV to 2 MeV, gamma

Range: 0 - 0.2 Roentgen

Leakage rate: 2% per 24 hrs

Power: NoneSize: 4" long, 1/2" dia.

Uses Model 2000A charger, $55

$45

A direct reading personal dosimeter. The roentgen scale is built intothe dosimeter and can illuminated by an external light source.

Victoreen Instrument Division10101 Woodland AvenueCleveland, Ohio 44104(216) 795- 8200

! -j~"-.-; ,") "j 0 f")

"~,,

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-DOSBeta, Gamma, X-rayVictoreen 4Dec. 1971

Class

Personal Dosimeter Reader/Charger

Victoreen Model 687C Minometer II

Laboratory

)Principleof Operation

Radiation penetrating a pocket chamber capacitor causes current toleak off in proportion to the amount of radiation. The resultingvoltage drop is calibrated in milliroentgens and is read on theMinometer II.


Perfonnance

Full scale ranges: 0-40 mRMinimum detectable energy:

Instrument accuracy: ~10%

Leakage rate:

0-200 mR

Dosimeters Model 362 362A

Radiation Detected Gamma &X-ray Gamma &X-ray

Gamma Energy Dependence ~15% from 30 keV to ~15% from 30 keV to1.2 MeV 1.2 MeV

Cs137 Calibration ~15% ~15%

Range 0-0.2 R 0-0.5 R

Overall Dimensions 5-1/2" long, 5-1/2" long,1/2" dia. 1/2" dia.

Price $12 $12

Requirements Power:Size:Weight:

100-130 V ac, 50 or 60 Hz, 15 VA10.75" long x 7.5" wide x 5.25" high9 lbs

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

STRAY RADIATION CHAMBERS(Supplement to Victoreen Minometer II)

RAD··DOSBeta, Gamma, X-rayVictoreen 4-Page 2, Dec. 1971

MODEL 208 208A 239 239A

Radiation X-Ray & X-Ray & X-Ray & X-Ray, GanunaDetected Ganuna Ganuna &Beta Ganuna &Beta

Accuracy +10% +10% +10% +10%- - - -Range O.OOIR and O.OOIR and O.01R and O.OlR and

0.002R 0.002R 0.002R 0.002RFull Scale Full Scale Full Scale Full Scale

. --r------.--------Energy +5%, 40 KeV +10% From +10% Down 35 KeV +10% fromDependence fo 1.2 MeV +15% 5 to 50 KeV +25% Down 20 KeV 5-50 KeV

Down to 30 KeV -

Overall 6 1/2" Long 6 1/2" Long 4 1/2" Long 4 1/2" LongDimensions 4 1/2" Dia. 4 1/2" Dia. 2" Dia 2" Dia

.,_... _..._- .~. -----_...~ ~-. ._-,....- .._. -_. _._--_.. -Cost $110 $175 $95 $145

Features

Cost

Address

Reader and charger for pocket chambers

$525

Victoreen Instrument Division10101 Woodland AvenueCleveland, Ohio 44104(216) 795-8200

(j ~) \"~J ~~JINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

G. RADIONUCLIDES

/RAD-NUCRadionuclidesContentsOCt. 1973

1. Tri tilnn

2. Krypton - 85

3. Radon - 222 and Its Daughters

4. Strontium • 90 and 89

5. Iodine - 131 and 129

6. Radium

7. Uranium

8. Plutonium

9. Instrument notes

.J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

T R I T I U M

1. Introduction

2. Tritium in Water

a. Liquid Scintillation Countingb. Tritium in Flowing Waterc. Urinalysisd. Solid Scintillation Counting

3. Tritium in Air

a. Ionization Chambersb. Proportional Countersc. Silica Gel/Liquid Scintillationd. Bubbler Exchangee. Combustion for HT Determinations

4. Enrichment Techniques

5. Summary and Conclusions

6. Acknowledgment

7. References

RAD-NUCTritiumPage 1

~..

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

,j


1. INTRODUCTION

Tritium (the hydrogen isotope of mass 3)is one of the most important radioactive nuclides released to the environment during thenormal operation of light water nuclear reactorsand their fuel reprocessing plants. Tritium isproduced principally in ternary fission in thereactor core and to a much lesser extent byactivation of the primary cooling water. Thefission yield of tritium (tritium atoms perfission) is about 0.01% (Ref. 1), and in fuelready for reprocessing (~lSO days of cool-down)it is present at the level of about 700 curies/metric ton of fuel (Ref. 1). Tritium is alsoproduced by neutron irradiation of thedeuterium, 3He, lOB, and 6Li in the reactorcoolant (Ref. 2); Table I (from Ref. 3) showsthe estimated tritium production (Ci/yr) attypical nuclear power stations of the boilingwater (BWR) and pressurized water (PWR) types.Essentially all of the tritium produced isultimately released to the environment, eitherat the reactor or most probably during fuelreprocessing. Tritium appears predominantlyas tritiated water (HTO), and to a lesserextent as hydrogen gas (HT). With the use ofZircaloy-clad fuel rods in light-water reactors,tritium diffusion from the spent fuel should bevery small ($1%), so that most of the releaseoccurs at the fuel reprocessing plant (Ref. 4).With the increasing number of nuclear powerplants, the world-wide inventory of tritium isexpected to rise dramatically. One projectionis shown in Figure 1, from Ref. 1. Krypton-8Sis also shown for comparison.

Tritium is also produced at heavy-waterreactors and at tritium production facilities,at which its relative importance is generallygreater than that of all other radionuclidehazards combined (Ref. 4).

Tritium's radioactive decay has a halflife of 12.36 years. The decay is by S- emission.Figure 2 (from Ref. 5) shows the beta energyspectrum. The very weak beta has a maximumenergy of 18.6 keV and a most probable energyof 5.7 keV. (The maximum range of an 18 keVbeta is about 6 microns in water or 0.5 em inair.) There is no other decay mode. One gramof pure tritium would have an activity of about9600 curies.

Tritium appears naturally in the environment at an estimated world-wide level of from20 to 60 megacuries (Ref. 4), corresponding toa mass of 2 to 6 kg. All but a fraction of onepercent is in the form of HTO in the air andwater. The fractional atomic concentrationrelative to ordinary hydrogen is about 4 x 10- 15(HT/Hz) in the atmosphere; about 8 x 10- 17(HTO/HzO) as vapor in air; and about 1 x 10- 18in surface water (Ref. 4). Most of the naturallyoccurring tritium is produced by interactions inthe upper atmosphere of the primary cosmic rayprotons (Ref. 6).

Production of tritium by atmosphericnuclear tests has dwarfed the natural levels:the tritium yield of a thermonuclear reaction(fusion) has been estimated at about 1 kg permegaton equivalent (Ref. 4, 7). Essentially100% of the tritium produced in this way isconverted to HTO water vapor (Ref. 8). Theconcentration in stratospheric water of tritiumrose from about 0.03 pCi/em3 (in the periodprior to nuclear testing) to about 20,000 pCi/em3in 1960, an increase of almost six orders ofmagnitude (Ref. 4). Although it is chemicallyidentical to normal hydrogen for most purposes,stratospheric tritium may not mix quickly andthoroughly with much of the naturally-occurringwater.

TABLE I.

Estimated tritium (3 H) produation at nualear power stations, Ci/yr (Ref. 3).

(Power level approximately 1000 MWe and 3300 MWt)

Source Reaction BWR PWR

coolant water ZH(n,y)3H 8 3

dissolved boron 10B(n,2a) 3H 0 600

uranium fuel rods fission 13,000 13,000

boron control rods lOB(n,2a)3H and S,OOO 0

010B(n,a) 7Li,

7Li(n,na)3H

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING


""

3000

40

0.2

l68-hourlimits,

individuals ingeneral public

l68-houroccupational

limits

30,000 pCi/cm3

400 "

2 "

In terms of curies, these permissiblelevels seem at first glance to be very high incomparison to MPC levels for other radionuclides.There are three reasons for this: first, thereis a large amount of water in biological systems,in which ingested tritium can be diluted; second,there is no known biological or physical reconcentration mechanism; and third, the tritiumbetas have very low energy.

Tritium seems to have a biological half-lifeof about 8 to 10 days in humans (Ref. 11, 12,13), which is similar to that of the gross watercontent of the body.

For l68-hour occupational exposures, theInternational Commission on Radiological Protection (Ref. 9) has established maximum permissable concentrations in air and water (MPC)aand (MPC)w, as well as maximum permissible bodyburdens OMPBB). For individuals in the generalpublic, the applicable MPC values are a factorof 10 smaller than for occupational exposure;and for exposure to a suitably large sample ofthe general public, another factor of 3 smallerstill. The U.S. Atomic Energy Commission (Ref. 10)has established MPC levels identical to thoseof the ICRP.

The occupational MPBB values are 1 mCi ofHTO in body tissue, or 2 mCi in the total body.The MPC values are as follows:

as HTO in water

as HT gas in air

as HTO vapor in air

~3H

productionrote

f3~curies/YearJ

accumulated(curies)

85Kr accumulated (curies)

85Kr productionrate

(curies/year)

2105 L.--_..L--_-L..-_~_ __'___-J

1960 1970 1980 1990 2000 2010

Calender year ending

Q)"0

(,) 2~

c:108.2

"00 5~-0II)Q).~

~

u

FIGURE 1. Estimated ppoduation of tpitium (3 H)and xrypton-85 fpom the nuaZea:r> powepindustpy of the fpee wopZd (fPomRef. 1).

Measurements of tritium are difficultmainly because of the low energy of the tritiumbetas, which can be counted by only a few of themany detectors sensitive to ionization energyloss. The discussion below is intended to pointout the advantages and disadvantages of thevarious existing (or proposed) measuring systemsfor tritium.

We shall concentrate upon measurements inthe air and water around nuclear reactors andtheir fuel-reprocessing plants. We do not intendto imply that tritium is not now a significantproblem outside of the reactor industry. Itsuse is increasing in medical and biologicalresearch as a tracer, and in industrial applications. A recent study (Ref. 14) of tritium'suse in luminous watch dials is interesting, ifonly because of its historical connection with -)the problem of the radium dial painters of .~.several decades ago. A recent study of theUnited Kingdom (Ref. 15) indicates that tritiumis widely used in industry and that "the radiation

Avg.fl energy 5·7 keV

100 Energy keY 18·6

80 - %Emission 100

% Type of (3-emission

40

t0·009 0'015

Particle energy, MeV'

FIGURE 2. Beta enepgy speatpum fop tpitium(fPom Ref. 5).

~-""I".J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

. "


doses received by some workers are not inconsiderable." What was found was that a few percent of the workers studied received dosesless than but comparable with MPC levels. Background information on the use of tritium inbiology and medicine can be found in the recentbook by Feinendegen (Ref. 16).

We will consider four distinct measurementproblems: determinations in water, in air asHTO, in air as rIT, and in urine. In turn, anyof these (except that in urine) can be made ineither environmental samples or process samples(water flow or gas stack). We shall attemptto discuss these various classes separately,where appropriate. Measurements in urine,however, will only be touched on briefly here.A fuller discussion can be found in Volume 4("Biomedical") of this Survey.

Various interferences must be considereddepending on where, when, and how the tritiumconcentration is being sampled or measured.In the gas phase around fuel reprocessingplants, the ~rincipal beta emitter besidestritium is 8 Kr, whose higher energy beta(Emax = 672 keV) can provide a significantinterfering background. In the liquid phase,strontium-90 (Emax = 546 keV) is present andmay interfere.

The literature on tritium measurements isvoluminous, more so than perhaps for any otherradionuclide of interest in environmentalmeasurements. The IAEA held a Symposium in1961, the proceedings of which (Ref. 17) are abasic reference in this field. A TritiumSymposium was held in Las Vegas in September,1971 (Ref. 18), in which the major researchgroups in the field summarized the currentstatus of instrumentation at that time. Also,a monograph by Jacobs (Ref. 4), part of theA.E.C. Critical Review Series, is an excellentreference on the sources of tritium and itsbehavior in the environment. Two recentbibliographies by Hannahs and Kershner (Ref.19) and by Rudolph, Carroll, and Davidson(Ref. 20) are also valuable.

In the literature on tritium, one frequently encounters the use of the Tritium Unit(TU) or Tritium Ratio (TR), defined as a tritiumconcentration of 1 tritium atom in 1018 normalhydrogen atoms. A concentration of 1 TU inwater corresponds to 3.23 x 10- 3 pCi/cm 3 ofwater, or alternatively 0.12 dps/liter.

Another notation which often appears isthe designation 'protium' for normal hydrogen(lH), to distinguish it from deuterium (2H)and tritium (3H). The three isotopes are alsocommonly denoted by H, D, and T.

2. TRITIUM IN WATER

In water, tritium occurs primarily as HTO(tritiated water). It is also occasionallyfound in tritiated organic compounds dissolvedor suspended in water, but we shall not discussthe measurement of these cases except whentheir measurement is contained within the measurement of HTO itself.

As mentioned above, the maximum permissibleconcentration (MPC) of tritium as HTO in liquidwater for an indivi~ual in the general population is 3000 pCi/cm3

• This MPC corresponds to110 disintegrations per second per cm 3 (dps/cm3

).

The main measurement problem is the low energyand range of the beta (the maximum range inwater being 6 microns).

A. Liquid Scintillation Counting

Efforts to obtain sensitive, reliablemeasurements have essentially all relied on onetechnique: liquid sointillation oounting. Thereare many liquid scintillation systems in theliterature and several are available commercially.Here we shall try to summarize the properties ofthe various liquid scintillation systems. Tworecent books are excellent references on thissubject: one edited by Horrocks and Peng(Ref. 21), and the other edited by Bransome(Ref. 22).

Liquid scintillation counting relies on thefluorescence of scintillator molecules excitedby the deposition of ionization from the beta.Energy given to solute molecules by the S istransferred to a fluorescent molecule which itexcites. A photon is emitted when the excitedmolecule returns to its ground state. For mostcommon scintillator solutes, the fraction ofexcited molecules which de-excite by photonemission is about 90%. The photons emitted aredetected by a multiplier phototube (MPT), orin the case of tritium nearly always by a pairof ~WT's in time coincidence.

A good discussion of this technique hasbeen given by Horrocks (Ref. 23):

"The main advantage obtained fromthe use of liquid scintillation countingas opposed to other conventional countingmethods has to do with the fact thatthe sample containing the radioactivityis in intimate contact with, and inmost cases dissolved in the detector.This produces the ideal 4TI geometry.A limiting factor in the liquid scintillation counting system is the MPT.Even the best MPTs have photocathodeefficiencies for conversion of photons

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Even more sensitive systems are available,using emulsions. Lieberman and Moghissi (Ref. 25)report a Y-value of 0.7 pCi/cm3 using the detergent Triton NlOl (Rohm &Haas Co.) in scintillation solution at a ratio of 1:2.75. This mixturecan hold 40 to 50% water, when the scintillationsolution is p-xy1ene containing 7 g PPO and1.5 g bis-MSB per liter. This cocktail has acounting efficiency of ~23% for the tritiumbeta. By using three photomultipliers viewinga large-volume (250 m1) vial, Moghissi (Ref. 26)has achieved a Y-value of 0.2 pCi/cm3

•

Calibration and standardization of systemsas sensitive as these are difficult problems.The National Bureau of Standards has tritiatedwater and tritiated-toluene standards (Ref. 27).The most frequently used calibration method isthe 'internal standard', in which a standardactivity (e.g., from NBS) is used interchangeably with the unknown samples. The problemis that the addition of a standard can change

into electrons of only 28% ••.•

"The liquid scintillator solution consists of three main parts.The bulk of the solution is the solvent,usually an alkyl benzene (i.e.,toluene) or dioxane. To the solventan organic compound (or compounds) isadded which is an efficient photonemitter and which emits photons inthe wavelength region which is easilymeasured by the MPT. And finally theliquid scintillator solution containsthe s~le; although there are someuses where the excitations are generated by an external sample. The mosttroublesome problem encountered withliquid scintillation counting involvesthose problems associated with theintroduction of the sample into thescintillator solution in a homogeneous(or near homogeneous) form withoutcausing a drastic reduction in photonemission due to so called quenchingprocesses•..•

"Quenching is defined as anyof those mechanisms which lead to adecrease in the number of photonsemitted by a scintillator solution.There are two basic types of quenching;chemical and color. Chemical quenchinginvolves the action of foreign materialsupon the excited molecules; eithersolvent or solute molecules. Energyis removed from the excited moleculesby a process which does not involvethe emission of photons. Colorquenching involves the re-absorptionof emitted photons by foreign materialwhich may be present in the liquidscintillator solution or sample.The re-absorbed photons will produceexcited molecules which de-activateby non-radiative processes.

"The overall effect of theseprocesses is the decrease in the averagenumber of photons emitted per unitenergy of exciting particle stoppedin the solution. It is important tokeep in mind that a 50% quenching ofphoton yield does not mean a 50% decrease in counting efficiency. Indeedthe same amount of quenching willproduce a greater change in countingefficiency for tritium than for 1 4C. "

Recent papers by Moghissi et al. havestudied the significant factors which affectlow-level liquid scintillation counting oftritium, both in homogeneous liquid systemssuch as solutions (Ref. 24), and inemulsions (Ref. 25). From the paper onhomogeneous solutions (Ref. 24), severalconclusions are important:

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Plastic vials are preferable to glass vials;"glass seems to decrease the counting efficiency for tritium counting and increasethe background as compared to plastic."

The solution which optimizes counting efficiency is 6 to 7 g of PPO, 1.2 to 1.5 gof bis-~ffiB, and 120 g of naphthalene perliter of dioxane. [PPO is 2,5 - diphenyloxazole; bis-MSB is p-bis-(o-methylstyryl)-benzene.] Various studies ofconcentrations were conducted to determinethis optimum.

In this solution, the optimum water contentis about 1 ml water/4 ml solution. Thereare two competing processes here, namelythat additional water increases quenchingat the same time that it increases theproportion of water which contains theactivity.

Phosphorescence is severe, and "in considering the long-lived component ofphosphorescence, it is desirable to avoidany light which might excite the scintillation solution" (Ref. 24).

A constant check of possible instrumentdrift is required for precise measurements."The recommended order of counting is:background, sample, standard calibrationsample, duplicate of sample, background."

"The preparation of water samples is simpleand consists of a single distillation."(In fact, some samples require no distillation at all.)

The Y-value (defined as minimum detectableactivity at a confidence level of onesigma of statistical error for one-minutecounting time) is about 1 pCi/cm3

•

,.}

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING


Time (minutes)

FIGURE J. Response of the flowmeter desaribedin Ref. Jl. Analog reaording ofratemeter output for five injeatedtritium water samples.

and is stirred for thorough mixing twice beforeexit. Time response is remarkably good:Figure 3 (from Ref. 31) shows the response to5 tritium samples of 10, 20, 30, 40, and 50 ~l,

injected instantaneously with a scintillatorflow rate of 7.0 ml/min. Residence time wasless than two minutes in the test, and the totalresponse peak is over in about 4 minutes, asseen in Figure 3. The efficiency for detectionof the tritium beta is 32%. The sample flowrate is 0.5 ml/minute, and the minimum detectable tritium concentration is about 25 pCi/ml.This system shows great promise for the continuousmonitoring of tritium in flowing water. Itsmain drawback is the high operating cost fromconsumption of liquid scintillator: at 7 ml/minute(~10 liters/day), the annual cost of liquidscintillator can be in the range of $9000 to$15,000 ($3 to $5 per liter).

EQ.u

i .. fo~ Fiv~ Injeded T,itlv';' Wale, Sample, JI ' I, 1-90

I 'T ' +-f-+- ''I _J' ;j'i-l~ ., ' '

"'1'" '±----' ',' ,t, 6J-----j~ -r:- _ Tri,tium labeled waterl~~ x 10 dpm/ml ~ o~

E ," I j H ~ t- 1----- 13' -t- a- c---I--- -.- ---f-f----- -- -1lIt' ....~ - '0 ("') -f----r- 8-- I .--601I.LO . ~. ,0- Ie I,

----~t-- ,'t~ -+~-J--ifr---- - --:+1~rr- 0 ., i C"l I 'CX1-f-- -- -+-50- '~Lf~- _+-~__L~ ___ ! - -+--p.)T. o I II ~-;r,J

, ,,\) C"l,' ~I,1-- --~'-J-~,-c--- t- ~- -1', J '~~~ET II . ~ _~+_

/ 20 Q:. 8--1--20--, {

A i+-1--- ,I :f· aJ' ~-lC-

1

j I IJ . c---

..J IJI' 1iiM1,I, WII' J1 t .1

~9--- '-10 LO 10 0.

the counting efficiency, due to differences inquenching. This problem can be overcome by theaddition of a very small (microliter) amount ofa high-activity standard to a previously countedsample, but accurate measurements of small sizesamples, usually made gravimetrically, aredifficult and tedious.

B. Tritium in Flowing Water

Measurements in flowing water can, ofcourse, be made by taking grab samples forbatch counting. A continuous flow-system withcontinuous measurements would be more desirable for many measurement situations. Therequirements of such a system are that it besufficiently sensitive and precise; that itrespond in time comparable with the characteristic time for a change in tritium concentrationin the flowing water; that it sample properly;and that it not be too expensive nor requireexcessive maintenance.

Moghissi and Carter (Ref. 28) have usedtwo samples which differ only in that oneemploys normal and the other tritiated naphthalene. This minimizes most of the errorsdue to chemical differences.

Ting and Litle (Ref. 31, 32) have reportedon a continuous flow system, developed at Beckman Instruments for use in the secondarycoolant of a pressurized water reactor. Whenthe device was field-tested, the tritium levelsin this coolant at the San Onofre NuclearGenerating Station (Ref. 32) were in the regionof 1500 pCi/em3 (about half of the MPC),measured with a few-percent precision.

Another method is to use one or moreradioactive gamma sources placed outside of thecounting vial (the so-called 'external standardmethod') • These can be used to adjust the gainon the photomultiplier tubes, or to partiallycompensate for differences in quenching characteristics among several samples in a train.Systems with automatic feedback control, usingradioactive sources, are available from someof the commercial liquid-scintillation manufacturers. Both the American Public HealthAssociation's Standard Methods (Ref. 29) andthe American Society for Testing and Materialscompilation (Ref. 30) contain standard methodsusing liquid scintillation counting for tritiumanalysis.

The system works by mixing toluene-basedliquid scintillator (or dioxane-based scintillator if very rapid mixing was required) withthe liquid water sample in a mixing chamber;the mixed solution flows through a light trap,a liquid scintillation counter, and then outas waste. The difficult part of the systemis the mixing chamber. Liquid scintillatorflows continuously into a vial; the watersample enters the vial by dripping gravity flow,

C. Urinalysis

Tritium measurements in urine are discussed in detail in Volume 4 ("Biomedical") ofthis Survey.

The most common procedure for the determination of tritium body burden is radioassayof tritium (as HTO) in urine. Chronic exposureof workers to air containing HTG vapor at the

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING


A.E.C. recommended occupational MPC level willproduce tritium activity of about 30 000 pCi/cm3

of urine (Ref. 33, 34). '

Levels down to the 10 pCi/cm3 region canb: measure~ routinely with liquid-scintillahon countlllg (Ref. 35), using an emulsiontechnique similar to that described earlier(Ref. Z5). Thus sensitivity is not a problemfor analysis in the laboratory. For rapidmeasurements, which are sometimes requiredafter possible large accidental exposures,Osborne has developed an automatic liquidscintillation urine analyzer (Ref. 36). Thissystem provides a measurement two minutesafter the sample is introduced, with a minimumsensitivity of about 1000 pCi/cm3 and measurements up to 10 7 pCi/cm3 with precisions ofabout ±10%. This device is particularly useful to assess a possible HTO exposure immediately after an accident.

One difficulty with urinalysis is the~ossible quenching due to foreign substancesIII the sample. This is the reason that thep-xylene-based emulsion technique is preferredover the.homogeneous-solution method (Ref. 35).AlternatIvely, one can distill the uranium?efore determining the tritium activity levelIn any of the conventional dioxane-basedsystems.

Block, Hodgekins and Barlow (Ref. 37)have developed a proportional counter tech-

Phototube <\1'1

View

Outlet

nique which can detect 1000 pCi/cm3 and isrelatively simple. The system is based on thereaction of water and calcium carbide to formacetylene as follows:

CaCZ + ZHZO + CZHZ + Ca(OH)Z

Tritiated water yields tritiated acetylene(~2HT), used as a counting gas in the proport~onal counter. This system is attractive partIcularly for its adaptability for use in thefield, despite the fact that its sensitivity ismuch less than that of the liquid scintillationsystems.

.Sandi~ Labora~o:ies (~ef. 38) have developeda urInalysIs capabIlIty uSIng metallic calciumto reduce the water in urine; a sealed ionchamber is filled with the evolved hydrogen. The~in ~dvantage o~ the instrument (the T-449) is anlmm:dIate ~nalY~Is capability for use in emergencyaccIdent sItuatIons. The calcium cartridge isdisposable, and the instrument makes determinations in five minutes, with ±15% accuracy (Zo)down to levels of 10,000 pCi/cm3

• This instrument is portable (18 lb), and is useful forfield use in case large exposures occur in aremote location.

D. Solid Scintillation Counting

Although liquid scintillation counting hasb7en the most commonly used technique for tritIated water measurements, plastic scintillation

3 mm dia. anthracene coated rods

(100 in detector)

View

NOtCl: All construction materials

are PIClxiglassiB>

6) Trademark - Rohm &. Haas

FIGURE 4. Schematic diagram of the scintillation detector (from Ref. 59).

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j , .~

I.:';'O!I' ;£~


\i

systems are also used. These systems haveseveral drawbacks compared to the liquidscintillation systems, but two advantages:first, plastic scintillation systems providefaster response than the liquid methods; andsecond, the liquid system can be expensivedue to consumption of large amounts of theorganic solvents and solutes, which must bedisposed of after use.

One needs a high surface-to-volume ratio,and the early systems used small crystals ofanthracene. More recently, various kinds ofdetectors using thin sheets or layers ofanthracene or plastic scintillator spreadover lucite (for light piping) have been described. Figure 4 shows one such detector(Ref. 39), in which 100 rods of lucite arecoated with anthracene powder. The countercan detect 1000 pCi/ml of water at a rate of10 cpm. To measure urine, the sample must bedecolored by passage over a charcoal column.The response to tritium in air is 20 cpm for1 pCi/cm3 of air. In an unshlelded laboratory environment, the normal external background gamma levels were at about 30 cpm.

Osborne (Ref. 40) has developed aplastic detector, shown in Figure 5, withthe sensitivity of 24 cpm for 1000 pCi/cm3 ofwater • At this counting rate, small fractionsof an ~WC)w can be detected easily. Fortritium in air, about 0.01 pCi/cm3 can be detected. The background is about 40 cpm.

The main problem with plastic detectorsis that over a period of time the plasticsurfaces tend to degrade because of sedimentation, bacterial growth, and discoloration.Any of these can produce large decreases incounting efficiency because of the diffiCUltyin light collection through the thin lightpaths. The detector can sometimes be cleaned,but not always. At present, this techniquedoes not compare favorably with liquid scintillation counting for effluent water monitoring, although when specific activity ishigh and the water sample is pure it can beused satisfactorily.

3. TRITIUM IN AIR

In air, tritium occurs primarily in twoforms: as water vapor (HTO) and as hydrogengas (HT). Tritiated organic compounds inthe vapor phase and on particulate matteralso occur occasionally.

There are two common approaches to measurements in air: first, one can use anionization chamber or gas proportional counterwith filtered air introduced for internalcounting; the tritium betas produce ionizationwithin the sensitive chamber volume. Thismethod is sensitive to tritium in all of its

FIGURE 5. Deteator for tritium in water. Thesaintillator sheets fit into a aubialuaite aell. The luaite plate shownhere~ on whiah the sheets are mounted~

forms one vertiaal side of the aeU(from Ref. 40).

gaseous chemical forms. Secondly, HTO vaporcan be removed from the air with a bubbler orwith some dessicant such as silica gel or amolecular sieve, and the resulting tritiatedwater counted using one of the liquid or plasticscintillation techniques. To measure tritiumas HT or in tritiated organics, it is possibleto burn the gas, converting the tritium to HTObefore dessication and counting. We shall discuss each of these methods in turn.

A. Ionization Chambers

The earliest tritium detector for stackeffluent measurements was the Kanne chamber(Ref. 41, 42, 43), developed in the early 1940's.The gas to be measured is drawn continuouslythrough an electrostatic precipitator or iontrap, then into a large ionization chamber. Theresulting current is measured with a picoammeter.Large chambers of volumes 18.5 and 51.5 litersare in common use at Savannah River Laboratory(Ref. 44); they have minimum sensitivity limits(20) of 7 and 2 pCi/cm3 in air, respectively.

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RAD-mcTritiumPage 10

To quote from Ref. 44:

"Although these instruments aresensitive to unusual particulate airloading, external gamma radiation,and other radioactive gases, theseproblems are reduced by filteringthe air intake, by locating thechambers in areas of low gamma background, and by using moisture trapsbetween two chambers in series,respectively."

One important problem with ionizationchambers is the background in the presence ofexternal gamma fields •.•. there is no wayfor a single ion chamber to differentiatebetween external gammas and internal betas(or internal y's or a's). The background issuch that 1 mR/hr of gammas is about equivalent to 100 pCi/em3 of tritium in air(Ref. 45). To reduce this problem, onecommon procedure is to place two identicalchambers side-by-side, one sealed and theother open to the ambient air (Ref. 46).This reduces the interference by a factor of50 to 100 (Ref. 45). The limitation is inmaintaining identical air masses in the twochambers in the presence of fluctuations inambient pressure, temperature, and humidity.

If the gamma flux is directional, chambersadjacent to one another may not sample thesame flux. This problem is reduced in adesign by Osborne and Cowper (Ref. 47) inwhich the compensating chamber is placed inside the active chamber to provide equal response in all directions. A 40-liter chamberof this design has a minimum detectable limit(20) for tritium at levels as low as about1 pCi/cm3 of air. Instruments with 0.3 and1.2 liter volumes have also been constructed(Ref. 48).

Interference by other gaseous radionuclides is also a major problem for ionchambers. Particulates may be eliminatedwith filters, but radioactive noble gases(e.g., 41Ar, 8SKr) are inert and difficultto discriminate against. Each disintegrationof 8SKr produces many times the ionizationof a tritium disintegration. This major disadvantage is what makes an ionization chamberinappropriate unless tritium is known to bethe only significant radionuclide present.To overcome this, Osborne has reported thedevelopment of two chambers identical exceptthat one has "a self-renewing drying systemso that continuous subtraction (tritium +noble gases minus noble gases) can beaccomplished" (Ref. 49).

Waters (Ref. 50), in a review of generalproblems with ion chambers, reports thatfactors such as cigarette smoke, ions, aerosols,humidity, and memory effects can also cause

erroneous readings in ion chambers. He suggeststhe use of a micron pore size filter followedby an electrostatic precipitator. Also,materials such as rubber and some plastics(Ref. 51) are particularly susceptible toabsorption of tritiated water vapor, causinga low reading; later re-emission or exchangewith ordinary water vapor then produces anerror in subsequent measurements. Watersreports that: "Teflon is satisfactory but isdifficult to use because of its tendency tocold-flow under pressure."

For monitoring tritium in air, the ionization chamber is undoubtedly the most commonlyused instrument. Portable flow-through instruments of various sizes (typically with about1 liter chamber volumes) have been a mainstayin health physics despite the problems discussed.

Perhaps the most sophisticated instrumentof this type is the Sandia T-446 (Ref. 38),now available from Bendix Corporation (Ref. 52).This instrument is expensive (over $5000) butprovides a collection of features which makesit almost ideal for monitoring in those applications where accident-warning instlumentationis needed. The ion chamber output current isfed to a vibrating reed electrometer, thenamplified and measured. All electronics aresolid-state, on printed circuit boards. Itis sensitive down to about 5 pCi/em3 of airand up to 10 ~Ci/cm3 in seven decade rangeswith automatic range changing. It employs anelectrostatic precipitator, and has a 200 ~Ci

63Ni source plated to one electrode of theprecipitator. Ionization created by the sourceis used for self-contained calibration when theprecipitator is turned off. There are twoadjustable alarm levels which can be used todistinguish between immediate hazards and levelsin the region of a few occupational (MPC)a' Theinstrument is either portable (batteries) oralternatively the detector can be used inremote-sensing situations; it has a fail-safefailure indicator, automatic range changing,a filter to eliminate ionizing aerosols, andother features. The T-446's principal disadvantages besides the high cost are a sensitivity to external gamma fields and radioactive gases which is common to all ion chambers.

B. Proportional Counters

The gas proportional counter differs fromthe ionization chamber mainly in two respects:it is a pulse counting instrument, and itrequires a particular filler gas to which thesample of (tritiated) air is added. It offersan advantage over the ion chamber in thatenergy discrimination is possible by electronicdiscriminating on the output pulse height,whose size is proportional to the energydeposited. The essential disadvantage of thegas proportional counter is the continualconsumption of counting gas, lvhich is discarded

· (;j

.--j..1

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after being mixed with the tritiated sampleand counted.

Driver (Ref. 53) built a tritium counterof this type as early as 1956. More recently,Ehret (Ref. 54) has achieved a minimum. detectable concentration (20) of 0.1 pCi/cm3 of air,using a chamber of about 1 liter volume withmethane as the counting gas, to which is added20 to 30% air.

"Air is pumped through the counter bymeans of a small membrane pump. Atthe counter inlet methane is addedto the air within a small mixingchamber" (Ref. 54).

In this design, there must be a compromisebetween speed of response and inordinate consumption of methane. Using a methane flowrate of 25 liters/hour, a response time of afew minutes can be achieved. Ehret I s designalso includes an anti-coincidence proportionalcounter surrounding the tritium-sensitivecounter, to discriminate against the longerrange betas of 41Ar and 8 sKr • This countersuffered from "memory effects" due to absorption of tritiated water vapor (HTO) in plastictubes, an effect mentioned earlier. Use ofTeflon should eliminate this problem.

Block, Hodgekins and Barlow (Ref. 37)have built a large-area, thin window gas-flowproportional counter system: two countersare identical except that one has an aluminizedmylar window opaque to tritium betas while theother has a Formvar window thin enough toallow detection of tritium. This system canthus compensate not only for gamma backgroundbut also for the beta activities of 41Ar and8 sKr. The window is porous to the countinggas (propane), and the flow occurs because ofa positive pressure inside the counter. Thecounting volume is 0.2 liters. The windowis permeable to TzO and HTO (but not HT orTz). In a gamma flux of 3 mR/hr, the counterhad a minimum sensitivity in the region ofabout 1 pCi/cm3

•

C. Silica Gel/Liquid Scintillation

The use of silica gel as a dessicant toremove moisture (HzO, HTO) from air beforeliquid scintillation counting is a commontechnique for tritium determinations in air.In fact, it has been proposed as a "TentativeMethod for Analysis for Tritium Content ofthe Atmosphere" by the Intersociety Committeefor a Manual of Methods for Ambient Air Sampling and Analysis (Ref. 55). Its main advantage is its extremely high sensitivity.

In the Intersociety Committee procedure,a 12" x 1.25" diam. aluminum cylinder isfilled with silica gel (180 g). Silica gelcan absorb moisture up to 40% of its own

weight. Air is pumped at about 100 to 150cm3/minute through the silica gel column,which collects essentially all of the moisture.With this much gel, a continuous sample can betaken over as long as a two-week period; ofcourse, a smaller set-up can be used for shortersample-collection times.

Following the sample collection, the silicagel is heated in a distilling flask to removethe moisture. The distillate is then countedusing the liquid scintillation technique ofMoghissi et al. (Ref. 24). A sample of airat 30°C (86°P) and 100% relative humidity willyield 6600 pCi/cm3 of moisture when tritium(as HTO) is present at the (MPC)a concentrationof 0.2 pCi/cm3 for individuals in the generalpublic (Ref. 55). Also, the system has negligibleinterference from other radioactive nuclides,because they do not absorb on silica gel andfurther are eliminated in the distillationprocess. The largest source of systematicerror is the uncertainty in the volume of airsampled and the prevailing temperature, pressure,and relative humidity of the air. Also, tritiumas HT gas is completely excluded by this method.

Osloond et al. (Ref. 56) have reported adetection limit (20) of 2 x 10- 5 pCi/cm3 of airby counting the silica gel directly (withoutdistillation) in the liquid scintillationsystem.

The chief drawback of this system is thefact that concentrations are integrated over along time period (hours to days), and thateach batch analysis requires a separate procedure in the laboratory. The advantages arethat its sensitivity and precision are excellent,and it suffers from almost no interferences.Another drawback is that the desiccant must berenewed periodically, and this must be donebefore it becomes saturated.

D. Bubbler Exchange

Osborne (Ref. 45) has removed tritiatedwater vapor (HTO) from air using a water-filledgas washing bottle ("bubbler"). Moist air isbubbled through water, and exchange occursbetween the vapor and liquid stages. It is easyto sample a known volume of air so that theoverall collection efficiency is within a fewpercent of 100%. For example, Osborne citessampling for 10 hours at 10 cm3/sec (or for1 hour at 100 cm3/sec) through 200 cm 3 of waterwith an overall collection efficiency of 96-97%.One advantage of this method is that tritiatedhydrogen gas (HT) is selectively eliminated:in a bubbler system studied at Los Alamos, thecollection efficiency for HT was <0.1% underconditions in which HTO collection efficiencywas 90 to 95% (Ref. 57). Also selectivelyeliminated are noble gases: in Osborne'sexample (Ref. 45), "the ratio of noble gasactivity to tritium activity in the water would

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be <0.013% of the average of the ratio in thesampled air". A typical bubbler system issomewhat less sensitive than the desiccantapproach, with minimum detectable activitybeing in the region of 0.1 pCi/cms; however,this sensitivity may be acceptable in manysituations, given the convenience of themethod.

Osborne (Ref. 45) has also described amethod in which the bubbler can be tied ontoa tritium-in-water liquid scintillation detector for continuous monitoring. Many elements of this system would then be verysimilar to that described above in the discussion on "Tritium in Flowing Water".

are oxidized with the help of a 0.5% platinumon 1/8" diameter aluminum oxide pellets, ata temperature of 400°C maintained by a heatingjacket. Not only lIT, but also tritiatedorganics (such as CHsT, etc.), are convertedto lITO in this step. The lITO is then removedfrom the flow by Air Dryer #2. Both lITO(Drierite) samples are analyzed by liquid scintillation counting after the Drierite is dehydrated and the water vapor distilled undervacuum. Griffin has indicated (Ref. 60) thata palladium catalyst, operating at lower temperature, would be much easier to use than hisplatinum catalyst. Levels of tritium (instack gas) in the 0.2 to 2.0 pCi/cms regionwere measured with accuracies of ±8.5%.

E. Combustion for HT Determinations

FIGURE 6. Samplirl{] train for totaZ airbornetritiwn (from Ref. 58).

Techniques have been developed for theseparate determination of tritium in air asHTO (water vapor) and lIT gas. We shalldiscuss two different techniques here.

4. ENRICHMENT TECHNIQUES

Ostlund (Ref. 61) has developed anothertechnique. His procedure also converts lIT andother tritiated compounds into lITO (water vapor)by a catalytic combustion process; palladiummetal carried on a molecular sieve is used tocombust hydrogen in air to better than 98%.The resulting water is absorbed in the samecatalyst. Sampling times as short as 10 minutescan be used to measure tritium levels in the1 pCi/cms region, with errors in the 3 to 5%region.

Most measurements of tritium in environmental samples ordinarily do not require anenrichment step prior to counting. However,techniques for tritium enrichment have beendeveloped for those special cases in whichtritium levels are extremely small. Oneexample is in geological research, where studieshave been made of underground natural waterswhose ages are so great (many thousands ofyears) that tritium levels are minute ($lO-spCi/cms). Here we will not attempt to do morethan summarize some of the important work inthe field of enrichment.

Among the procedures used to enrich tritiumin water samples are electrolysis, thermaldiffus ion, and chromatography. Hoy (Ref. 62)has developed a chromatographic system inwhich a palladium column is heated; tritiumdiffuses through the column faster than doesnormal hydrogen, and the first gas evolved is

One difference between the two techniquesis that Ostlund's is better adapted to singlemeasurements, while Griffin's is designed forcontinuous, long-term sampling followed bybatch analysis of the integrated activity.Also, because in Ostlund's technique the catalystbase molecular sieve is also the desiccant,there is not a problem with contamination and''memory'' which might exist in the other technique. Either technique can perform independent measurements of lITO and lIT in air, asignificant advantage.

COOLINGCOILS

GAS

TANK

CARRIER#1

HEATINGJACKET

Griffin et al. (Ref. 58) have determinedlITO and HT separately, using a techniquewhose flow train is shown in Figure 6. BecauselIT (or H2) in the gas to be measured is present at very small levels, tritium-free H2gas is added as a carrier. The moisture(including HTO) is then removed in Air Dryer#1, consisting of Drierite-brand anhydrouscalcium sulfate in plexiglass cylinders(Ref. 59). The dry gas is combusted in acatalytic burner: all combustible compounds

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)

tritium-enriched. Tritium recovery of about60% was obtained in the first 500 ml of gasevolved, and with a 30-minute counting perioda T:H ratio of 10- 17 could be measured with±4l% (la) error. Perschke (Ref. 63) was ableto enrich tritium up to 40 times with 100%tritium recovery, using gas solid chromatographyon metal sieves.

Another approach is electrolysis. Whenwater is electrolysed, hydrogen is given offmore readily than tritium; the relative lossrate can be as high as 35:1, varying withelectrode material, surface conditions,electrolyte, and temperature. Hartley (Ref.64) has done a detailed analysis of the parameters involved in electrolytic procedures.Ostlund (Ref. 65) has achieved enrichments inthe 102 region by a series of successiveelectrolytic stages.

Thermal diffusion is another method usedfor tritium-hydrogen separation (Ref. 66) butit is complicated and time-consuming.

For further information on enrichmenttechniques, the interested reader is referred to the references cited.

5. SlJM\1ARY AND CONCLUSIONS

Three important numbers determine thesensitivity required of instruments for measuring tritium in environmental media. Theseare the ''Maximum Permissible Concentrations"QMPC) for an individual in the general population (Ref. 9):

3000 pCi/cm3 (as HTO in water)40 pCi/cm3 (as HT gas in air)0.2 pCi/cm3 (as HTO vapor in air).

The ideal instrument is one capable ofmeasuring down to fractions of MPC levels inthe appropriate medium. There are two mainclasses of measurements in each medium, thatis laboratory and field measurements. Therequirements are quite different in the twocases, since field instruments generally mustbe more rugged, require less maintenance, beless sensitive to temperature and humidityeffects, and have some method of automaticreadout (whether the measurements are continuous or batched). We shall summarize thesituation in each of the various measurementareas separately:

a) Laboratory measurements of HTO in water.The liquid scintillation technique is theestablished method for this task. It isextremely sensitive (sensitivities below1 pCi/cm3 of water), has excellent reproducibility, suffers from few interferences(especially if distillation precedes counting),and is now commercially available in a variety

of sophisticated, automatic systems. The disadvantages of liquid scintillation countinginclude both the high capital cost of equipmentand high operating costs. Plastic scintillatorsystems are less expensive and have faster timeresponse, but this is at the expense of perhapstwo orders of magnitude in sensitivity. Animportant disadvantage of these plastic techniques is that the surface tends to degrade intime.

b) Urinalysis. This is now a well-developedtechnique, using liquid scintillation countingmethods similar to those for HTO measurementsin water. Automatic analysis equipment canreach sensitivities in the range of 10 pCi/cm3

of urine. A proportional counter techniquesensitive in the 1000 pCi/cm3 range has alsobeen developed for portable field use.

c) Field measurements of HTO in (flowing)water. A system for continuous measurementsusing a flow/mixing system and liquid scintillation counting has recently been developed.Refinements of this technique seem capable ofultimately providing reliable, sensitive instream monitoring capability for routine reactoreffluent monitoring. Present sensitivities inthe 25 pCi/cm3 range seem adequate for effluentmeasurements, but can only be improved atpresent by using more scintillator at highercost.

d) Continuous field measurements of totaltritium in air. Flow-through ionizationchambers and proportional counters have beena mainstay for tritium-in-air monitoring fornearly 25 years. Several commercially-available instruments now exist. The ion chambersuffers from various types of interferences,most notably from external gamma fields;however, well-developed compensation systemsnow seem capable of measuring down to about1 pCi/cm3 in the presence of gamma fluxes inthe few-mrad/hour range. Ion chambers alsocannot distinguish tritium from other gaseousemitters (e.g., 41Ar, 85Kr), and are sensitiveto cigarette smoke, ions, and aerosols unlesssuitably protected (this protection is nowavailable in some commercial instruments).Gas proportional counters can partially discriminate against other radionuclides, andare less sensitive to aerosols. Their sensitivity (in the 1 pCi/cm3 range) is comparableto that of the ion chambers. To detect levelsmuch below about 1 pCi/cm3 in air, it isnecessary to remove tritiated water vapor fromthe air for liquid scintillation counting, oruse combustion techniques.

e) HTO in air by removal & liquid scintillation counting. There are two well-developedmethods for HTO (vapor in air) determinationsat very low levels: the use of silica gel,and bubblers, for removal of vapor. In each

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case, liquid scintillation counting measuresfITO in the resulting water. With silica gel,sensitivities well below 0.01 pCi/em3 of airare achievable; with bubblers the sensitivitiesare typically in the region of about 0.1 pCi/em3

•

These are both integrating techniques, capableof field sampling, ut the analysis is by batchcounting in the laboratory. Interferences arefew, and precision is high.

f) HT in air (aombustion). Combustion techniques followed by fITO counting can determinetritium as tritiated hydrogen gas (fIT) at thelevel of a fraction of one pCi/em3 of air.If HTO vapor is removed by dessication first,separate fIT and fITO measurements can be made.

CONCLUSIONSAt present, measurements at levels well

below MPC values for individuals in the generalpublic are possible in each of the importantmeasurement situations. In particular, laboratory liquid-scintillation analyses of batch

water samples (fITO in water, fITO vapor extractedfrom air) are extremely sensitive and sufferfew interferences. Unfortunately, thesemeasurements are time-consuming and expensive.These same comments apply to the IITO-in-watersystem for in-stream effluent measurements.

In air samples, continuous measurementswith ion chambers and proportional countersare only sensitive at about the 1 pCi/cm3 level~which is well above the MPC value of 0.2 pCi/emfor general public exposure. More sensitivemeasurements in air require vapor removal andlaboratory counting.

Clearly, advances are required to performcontinuous, low-level monitoring of tritiumin air. Also, cost-reduction in liquid (fITO)measurements is very desirable. Finally, theruggedness, reliability, and maintainabilityof many present field instruments is of thehighest priority.

6. ACKNOWLEDGMENT

For this section we particularly acknowledge the generousadvice and review of:

Seymour Block, Lawrence Livermore Laboratory

A.A. Moghissi, EPA National Environmental Research Center, Las Vegas

George A. Morton, Lawrence Berkeley Laboratory

R.V. Osborne, Atomic Energy of Canada Limited, Chalk River

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,)

7. REFERENCES


L "Siting of Fuel Reprocessing and Waste Management Facilities," Report ORNL-445l, Oak RidgeNational Laboratory, Oak Ridge, TN 37830 (July 1971).

2. L. Bramati, "Production of Tritium in Nuclear Reactors," p. 28-38 in Seminaire Sur LaProtection Contre les Dangers du Tritium, Service Central de Protection Contre les Rayonnements Ionisants, Le Vesinet, France, 16-18 April 1964 (CONF-6404l3).

3. H.L. Krieger, S. Gold, and B. Kahn, "Tritium Releases from Nuclear Power Stations," TritiumSymposium (Ref. 18). Authors' address is EPA National Environmental Research Center,Cincinnati, OH 45268.

4. D.G. Jacobs, "Sources of Tritium and Its Behavior Upon Release to the Environment," USAECCritical Review Series, TID-24635, USAEC Division of Technical Information Extension, OakRidge, TN 37830 (1968).

5. J. Mantel, "The Beta Ray Spectrum and the Average Beta Energy of Several Isotopes of Interestin Medicine and Biology," Int. J. AppL Radiat. Isotopes ~, 407 (1972).

6. L.A. Currie, W.P. Libby, and R.L. Wolfgang, ''Tritium Production by High-Energy Protons,"Phys. Rev. 101, 1557 (1956).

7. E.A. Martell, "On the Inventory of Artificial Tritium and Its Occurrence in AtmosphericMethane," J. Geophys. Res. 68 (13), 3759 (1963).

8. W.D. Bond, "Production of Tritium by Contained Nuclear Explosions in Salt: I, LaboratoryStudies of Isotopic Exchange of Tritium in the Hydrogen-Water Systems," Report ORNL-3334,Oak Ridge National Laboratory, Oak Ridge, TN 37830 (1962).

9. International Connnission on Radiological Protection, 100 Publication 2, "PermissibleDose for Internal Radiation," Pergamon Press, New York (1959).

10. U.S. Atomic Energy Commission, 10CFR20 (Code of Federal Regulations, Title 10, Part 20),"Standards for Protection Against Radiation," Appendix E, Table II, Concentrations in Air andWater Above Natural Background.

11. A.A. Moghissi, M. W. Carter, and R. Lieberman, "Long Term Evaluation of the Biological HalfLife of Tritium," Health Physics E., 57 (1971).

12. K.F. Wylie, W.A. Bigler, and G.R. Grove, "Biological Half-Life of Tritium," Health Physics2., 911 (1963).

13. I-I.L. Butler and J .H. LeRoy, "Observation of Biological Half-Life of Tritium," Health Physics11, 283 (1965).

14. A.A. Moghissi, E.D. Toerber, J.E. Regnier, M.W. Carter, and C.D. Posey, "Health PhysicsAspects of Tritium Luminous Dial Painting," Health Physics 18, 255 (1970). Also, S.L.Kaufman et aL, "Investigation of Tritiated Luminous CompouOOs," Report EERL 71- 2, EPAEastern Environmental Radiation Laboratory, Montgomery, AL 36101 (1971).

15. B.E. Lambert and J. Vennart, "Radiation Doses Received by Workers Using Tritium in Industry,"Health Physics~, 23 (1972).

16. L.E. Feinendegen, Tritium Labelled Molecules in Biology and Medicine, Academic Press, NewYork (1967).

17. International Atomic Energy Agency, Tritium in the Ph sica1 and Bio10 ical Sciences, Proceedings of an lAEA Symposium, in 2 vol., Vienna 19 1 •

18. Tritium, Proceedings of the Tritium Symposium, 30 August to 2 September 1971, Las Vegas,Nevada, to be published by the EPA National Environmental Research Center, Las Vegas,~114.

19. B.J. Hannahs and C.J. Kershner, "Bibliography on Handling, Control, and Monitoring ofTritium (Dec. 1968 to Jan. 1972)," Report MLM-1946, Mound Laboratory, Monsanto ResearchCorp., Miamisburg, OH 45342 (1972).

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20.

21.

22.

23.

24.

25.

26.

27.

A.W. Rudolph, T.E. Carroll, and R.S. Davidson, "Tritium and Its E~fects i~ the Enviro~ent -A Selected Literature Survey," Report BMI-17l-203, Battelle MemorIal InstItute, 505 KIng Ave.,Columbus,OH 43201 (1971).

D.L. Horrocks and C.T. Peng (editors), Organic Scintillators and Liquid Scintillation Counting,Academic Press, New York (1971).

E.D. Bransome (editor), The Current Status of Liquid Scintillation Counting, Grune &Stratton,New York (1970).

D.L. Horrocks, 'Measuring Tritium With Liquid Scintillators," presented at Tritium Symposium,Ref. 18.

A.A. Moghissi, H.L. Kelley, J.E. Regnier, and M.W. Carter, "Low Level Counting by LiquidScintillation - - 1. Tritium Measurement in Homogeneous Systems," Int. J. App1. Radiat.Isotopes 20, 145 (1969).

R. Lieberman and A.A. Moghissi, "Low Level Counting by Liquid Scintillation -- II. Applications of Emulsions in Tritium Counting," Int. J. App1. Radiat. Isotopes ,Q., 319 (1970).

A.A. Moghissi, "Analysis and Public Health Aspects of Environmental Tritium," p. 419 inAdvances in Chemistry Series, No. 93, "Radionuc1ides in the Environment," American ChemicalSociety (1970).

S.B. Garfinkel, W.B. Mann, R.W. Medlock, and O. Yura, "The Calibration of the National Bureauof Standards' Tritiated-Toluene Standard of Radioactivity," Int. J. App1. Radiat. Isotopes16, 27 (1965).

29.

28. A.A. Moghissi and M.W. Carter, "Internal Standard with Identical System Properties forDetermination of Liquid Scintillation Counting Efficiency," Anal. Chem. 40, 812 (1968).

Standard Methods for the Examination of Water and Wastewater, 13th edition, American PublicHealth Association, 1015 - 18th Street, Washington, DC 20036 (1971).

30. Annual Book of ASTM Standards, Part 23 (1971), American Society for Testing and Materials,1916 Race Street, Philadelphia, PA 19103. The tritium methods are designated D2476-70.

31. P. Ting and R. Litle, "Continuous Monitoring of Aqueous Tritium Activity," Beckman Instruments,Inc., Fullerton, CA 92634, presented at Tritium Symposium, 1971 (Ref. 18).

32. P. Ting and M.K. Sullivan, "Reactor Coolant Monitoring with a Discrete Sampling Flow CellLiquid Scintillation System," Report No. 558 (1971), Beckman Instruments, Inc., Fullerton,CA 92634.

33. G. Cowper, "Health Physics Instrumentation," Report AECL-3864, Atomic Energy of Canada Limited,Chalk River, Ontario, Canada (1971).

34. W.J. Brady and V.M. Mulligan, "Tritium Exposure Experience at the Nevada Test Site," presentedat the "Symposium on Instrumentation, Experience, and Problems in Health Physics TritiumControl, Sandia Corporation, Albuquerque, NM 87115, 16 February 1967."

35. A.A. Moghissi, R. Lieberman, M.W. Carter, and J.E. Regnier, "Improved Radiobioassay of Urinefor Tritium," Health Physics E, 727 (1969).

36. R.V. Osborne, "Automatic Urinalyzer for Tritium AEP-52l6," Report AECL-2702 (1968), AtomicEnergy of Canada Limited, Chalk River, Ontario, Canada. Also, "Performance of an AutomaticAnalyzer for Tritium in Urine," Health Physics ~, 87 (1970).

37. S. Block, D. Hodgekins, and O. Barlow, "Recent Techniques in Tritium Monitoring by ProportionalCounters," Report UCRL-51131, Lawrence Livermore Laboratory, Livermore, CA 94550 (1971).

38. R.P. Baker and R.D. Richards, "Reliable and Versatile Instrumentation for Detection ofTritium Hazard Designed for Military Applications," unpublished report, Sandia Laboratories,Box 5800, Albuquerque, NM 87115. Also, Sandia Report SC-M-68-245, "A New Family of TritiumMounting Equipment," Sandia Laboratories, Box 5800, Albuquerque, NM 87115 (1968).

,l."J

INSTRUMENTATION

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MONITORING

'.J


39. A.A. Moghissi, H.L. Kelley, C.R. Phillips, and J.E. Regnier, "A Tritium Monitor Based onScintillation," Nuc1. Inst. Methods 68, 159 (1969).

40. R.V. Osborne, "Detector for Tritium in Water," Nuc1. Inst. Methods !!...' 170 (1970).

41. W.R. Kanne, ''Monitoring of Gas for Radioactivity," U.S. Patent 2,599,922, June 10, 1952,filed October 12, 1944.

42. J.E. Hoy, "Operational Experience with Kanne Ionization Chambers," Health Physics &., 203 (1961).

43. E.C. Morris, p. 491 in Assessment of Airborne Radioactivity, International Atomic EnergyAgency, Vienna (1967).

44. W.L. Marter and C.M. Patterson, ''Monitoring of Tritium in Gases, Liquids, and in the Environment," American Nuc1. Society Transactions 14, 162 (1971).

45. R.V. Osborne, ''MOnitoring Reactor Effluents for Tritium: Problems and Possibilities,"Report AECL-4054, Atomic Energy of Canada Limited, Chalk River, Ontario, Canada (1971),presented at Tritium Symposium (Ref. 18).

46. J.D. Anthony, Nucleonics 1I, No.4, 110 (1959).

47. R.V. Osborne and G. Cowper, "The Detection of Tritium in Air with Ionization Chambers,"Report AECL- 2604, Atomic Energy of Canada Limited, Chalk River, Ontario, Canada (1966).

48. H.L. Kelley and C.R. Phillips, "A Review of Tritium Monitoring Devices," (1971) presentedat Tritium Symposium (Ref. 18).

49. R.V. Osborne, Chalk River Nuclear Laboratories (private communication).

50. J.R. Waters, "Pitfalls and Common Errors in the Measurement of Tritium in Air," Report J11-506,Johnston Laboratories, Inc., Cockeysville, MD 21030, presented at Health Physics SocietyAnnual Meeting, Chicago, 2 July 1970.

51. D.O. Nellis et a1., p. 35 of "Tritium Contamination in Particle Accelerator Operation,"USDHEW, Public Health Service Publication '999-RH-29, Washington, DC (Nov. 1967).

52. Bendix Corp., Box 1159, Kansas City, MO 64141, Attn: V.H. Clabaugh or J.W. Fraser.

53. G.E. Driver, "Tritium Survey Instruments," Rev. Sci. Instr. Q, 300 (1956).

54. R. Ehret, "Proportional Flow Counters for Measurement of Tritium in Air," p. 531 of Assessmentof Airborne Radioactivity, International Atomic Energy Agency, Vienna (1967).

55. Methods of Air Sampling and AnalYSis, Intersociety Committee for a ~~ual of Methods forAmbient Air Sampling and AnalySIS. American Public Health Association, 1015 - 18th Street,Washington, DC 20036 (1972).

56. J.H. Osloond, J.B. Echo, W.L. Polzer, and B.D. Johnson, "A Tritium Air Sampling Method forEnvironmental and Nuclear Plant Monitoring," (1971), presented at Tritium Symposium (Ref. 18).

57. A.M. Valentine, "An Investigation of a Bubbler Tritium Sampler," Report LA-39l6, Los AlamosScientific Laboratory, Los Alamos, NM 87544 (1968).

58. W.R. Griffin, J.A. Cochran, and A.A. Bertuccio, "A Sampler for Non-Aqueous Tritium Gases,"EPA Office of Radiation Programs, 109 Holton Street, Winchester, MA 01890 (1972), unpublished.

59. W.A. Hammond Drierite Company, Xenia, OH 45385.

60. W.R. Griffin, private communication.

61. H.G. Ostlund, "A Rapid Field Sampling for Tritium in Atmospheric Hydrogen," Report ML 70075,Rosenstiel School of Marine and Atmospheric Sciences, Univ. of Miami, Miami, FL 33149 (1970).Also, H.G. Ostlund, M.O. Rinkel, and C. Rooth, "Tritium in the Equatorial Atlantic CurrentSystem," J. Geophys. Research Zi, 4535 (1969).

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62. J.E. Hoy, "Tritium Enrichment by Gas-Solid Chromatography: Technique for Low-Level Analysis,"Science 161, 464 (1968). Also, D.W. Hayes and H.E. Hoy, "A Chromatographic System for theEnrichment and Analysis of Low-Level Tritium Samples," (1971), presented at Tritium Symposium(Ref. 18).

63. H. Perschke, M. Crespi, and G.B. Cook, "A System for the Enrichment of Low-Level Tritium inLarge Volume Hydrogen Samples by Gas Chromatography," Int. J. Appl. Radiat. Isotopes ~,813 (1969).

64. P.E. Hartley, 'TIesign and Performance of Tritium Measurement Systems Using ElectrolyticalEnrichment," Nucl. Inst. Methods 100, 229 (1972).

65. H.G. Ostlund and E. Werner, "The Electrolytic Enrichment of Tritium and Deuterium for NaturalTritium Measurements," p. 95, Vol. I of Ref. 17.

66. B. Verhagen, "Rapid Isotope Enrichment of Gases by Thermal Diffusion for Nuclear Dating,"p. 657 in Radioactive Dating and Methods of Low-Level Counting, International Atomic EnergyAgency, Vienna (1967). .

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INSTRUMENTATION

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MONITORING

KRYPTON-8S

1. Introduction

2. Radiation Protection Guide


a) Laboratory Techniques

(i) Plastic Scintillator

(ii) Liquid Scintillat9r

b) Field Instruments

(i) Flow-through Ionization Chambers

(ii) Geiger-Muller Counters

4. Swmnary and Conclusions

5. References

RAD-NUCKrypton-8SPage 1

\.. ..J ,)

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RAD-NUCKrypton-8SPage 3

1. INTRODUCTION

Krypton-8S is one of the main radioactivefission products normally released to the atmosphere in the reprocessing of nuclear reactorfuels. In fuel ready for reprocessing (150 daysof cool-down) it is present in the amount ofabout 11,200 curies/metric ton of fuel (Ref. 1).In all reprocessing plants presently operatingor under construction, the entire 85Kr contentof the fuel is released to the atmosphere.Since these plants operate at a through-put offrom one to six tons per day, 85Kr is a potential environmental pollutant, requiring measurement both in the plant stack during releaseand in the environment after dispersion. Withthe rise in nuclear power production, the worldwide 85Kr inventory is expected to increasedramatically. One projection is shown inFigure 1 (From Ref. 1).

A recent study (Ref. 2) indicates thatpresent world-wide dose to man averages about10- 3 mrad/year to the bare skin, and about 10-4

mrad/year to the whole body. Flgure 1 can beused to determine approximately how these dosesmight increase in the next few decades.

Krypton is a noble gas, chemically inert,which is present (as stable Krypton-78, 80, 82,84, 86) in normal air at a concentration of1.14 ppm = 1.14 ml/m 3 (Ref. 3). The radioactive decay of 85Kr has a half-life of 10.76years. The principal decay mode is f3 - eiiiISSTon,with a max:iIm.un beta energy of 672 keY. Thebeta has a broad energy spectrum shown inFigure 2 (from Ref. 4). The range for themax:iIm.un-energy beta is 0.3 g/cm2 (3 mm inwater, 2S0 cm in air). A small (0.41%) branchingratio also exists for emission of a S14-keVgamma.

Spectrum No: 1 2

Energy keY 150 672% Emission O' 7 99Type ofemission

o

100.---

80

% 60

40

Particle energy, MeVFigUT'e 2.

Kr 85Avg. fi energy 245·3 keV

2. RADIATION PROTECTION GUIDE

For l68-hour occupational exposures, theInternational Commission on Radiological Protection (Ref. S) has established a maximumpermissible concentration in air, (MPC) . Thisoccupational limit is 3 x 106 picocurie~ percubic meter (pCi/m 3) • For individuals in thegeneral public, the applicable MPC valuesare a factor of 10 smaller (300,000 pCi/m 3)and for exposure to a suitably large sample ofthe general public, another factor of 3 smallerstill (100,000 pCi/m 3). The U.S. Atomic EnergyCommission's MPC values agree exactly with theICRP MPC's just quoted (Ref. 6). Throughoutthis discussion, the MPC will be taken as300,000 pCi/m 3, since exposure to a few individuals in the general public at the 300,000 levelis undoubtedly more likely than to a largerpopulation at the 100,000 level.

'\3H

productionrate

f3~curies/YearJ

accumulated(curies)

1910 1980 1990 2Qill) 2010

CALENDAR YEAR ENDING

85Kr productionrate

(curies/year)

2105 L-_l..-._l--_L.------I_----I

1960

oI/)<I>.~

::JU

FigUT'e 1. Estimated Production of Krypton-85and 3H (Troitium) froom the Nuclearo Power' Industro'j

o-f the FPee World (fr'Oln Ref. 1).

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RAD-NUCKrypton-85Page 4

This MPC is equivalent to fractionalk~ton-85 atomic concentrations of 2.0 x 10-7

(8 Kr/total Kr) or 2.3 x 10- 11 (85Kr/total air).At the fence around a typical fuel reprocessingplant, concentrations of a few percent of MPCare expected to occur periodically.


In environmental samples, the measurementof 85Kr is essentially always based upon detecting the decay (3 -, with any of a number ofdetectors sensitive to ionization energy loss.Several detection systems exist, includingliquid scintillators, plastic scintillators,Geiger-Muller counters and ionization chambers.Each of the methods has its advantages anddisadvantages; the discussion below is intendedto point out some of the factors involved.

We shall concentrate upon measurements inthe air around nuclear reactors and theirfuel-reprocessing plants. Here the principalbeta emitter besides 85Kr is tritium (3B);however, the tritium (3- has such a low energy(Emax = 18.6 keV) that its interference in the85Kr measurement is usually not significant.(The reverse is not true, as discussed in thetritium section elsewhere in this volume.)

There are two quite different classes of85Kr measurement systems: those which operatein the field, designed to run unattended exceptfor periodic maintenance; and those whichrequire laboratory procedures. The latter areinvariably the more sensitive and the moreprecise. We shall discuss these two classesseparately.

a) Laboratory Techniques

There are a number of 85Kr techniqueswhich have been developed for use in the laboratory. They all involve one substantial handicap, namely, that the volume of gas which canbe sampled at some remote location and thentransported to the laboratory for analysis isnot large. This disadvantage limits sensitivity,but is counterbalanced by the ability to concentrate the krypton before counting and to perform other analytical procedures which are impossible to carry out in the field.

The two most common laboratory techniquesuse plastic-scintillator shavings containedwithin a gas-tight vial, and liquid scintillator as a solvent for the 85Kr-containing gas.

(i) Plastic Scintillator

We shall discuss the technique ofSax, Denny, and Reeves (Ref. 3), which istypical of the plastic scintillator methods.

Plastic scintillator shavings of 20-40mesh (an inexpensive by-product from any

of several scintillator manufacturers) areencased in a glass vial of volume about 4 mI.A sample of pure krypton gas is prepared usingvacuum-cryogenic techniques. The vial isevacuated and then filled to a known pressure(near 600 torr) with the krypton samples. Ascintillation counter then measures the pulseheight spectrum.

Calibration of the counting efficiency(the fraction of the (3 spectrum above thecountin~ threshold) is determined using aknown 8 Kr standard acquired from NBS (Ref. 7).The counting effluency is about 95%. Givenabout 0.5 ml of nearly pure krypton (equivalentto that present in about 0.5 m3 of air),measurements can be made of normal 85Kr background levels in the 10 pCi/m 3 range to about±10% (Ref. 3). The limit of detection isabout 1 pCi/m 3 of air sample, with a 100minute counting time, at the two-standarddeviation level above background.

(ii) Liquid Scintillator

A general description of liquidscintillation counting can be found in thesection on "Tritium" elsewhere in this volume.Here we shall discuss that aspect of liquidscintillation counting which is unique to orparticularly relevant to 85Kr.

The liquid scintillator method reliesupon the high solubility of krypton in manyof the commonly used liquid scintillators.Krypton is soluble (Ref. 8, 9) in aromaticsolvents to ~(l ml Kr)/(ml solvent).

The earliest descri~tions of liquidscintillators used for 8 Kr counting are thoseof Horrocks and Studier (Ref. 10), and Curtis,Ness, and Bentz (Ref. 11). Those early methodssuffered from a limit on the amount of kryptonwhich could be introduced into the solution.

Shuping, Phillips, and Moghissi (Ref. 9)have reported a method in which about 25 mlof toluene-based liquid scintillator acts assolvent for about 10 ml of gas. The gas isintroduced into an evacuated glass vial, filledwith deaerated scintillation solution. "Ifthe 85Kr concentration in air is sufficientlyhigh, the sample may be introduced directlyinto the solution and successfully counted"(Ref. 9). More commonly, krypton is concentrated cryogenically. A rate of 1 c~m abovebackground corresponds to 0.025 pCi 5Kr/m 3

of air, so that levels of that order of magnitude are detectable with the method. Accuraciesin the ±4% range are achieved, when 85Kractivities of ~10 pCi/m 3 of air are present.

One of the more difficult problems inthe procedure just described is the separationof krypton gas from the main air sample. Toovercome this problem, a separation systemfor krypton, by Cummings, Shearin, and Porter

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)

1~_/J

(Ref. 12) employs 83mKr as a spike in the airsample, in order to determine directly the 85Kryield after a complicated separation procedureinvolving "charcoal and molecular sieve coldtraps, calcium sulfate, ascarite, and a titaniumfurnace (900°C) for the removal and separationof other air constituents from krypton" (Ref. 12).A description of a method for generating 83mKr(2-hour half-life) from 83Rb in the laboratoryhas been given by Moghissi and Hupf (Ref. 13).

Another 85Kr system, described by Stevensonand Johns (Ref. 14), uses a battery-operatedair compressor to collect 1 m3 of air in thefield. After a series of cryogenic absorptionsand elutions in the lab, the krypton is dissolvedand counted in a liquid scintillator. Thekrypton recovery ranges from 50 to 70%, measuredvolumetrically. These workers report a minimumdetectable sensitivity (three standard deviationsabove background) of about 2 pCi 85Kr/m3 ofair, with a 4-hour counting time.

b) Field Instruments

For measurements in the field, the idealgoal is an instrument which can record continuously, with reasonably short time-integrationperiods, at sensitivity levels well below thecurrent average background of about 10 pCi/m 3

of air. The ideal instrument must also berugged enough to withstand temperature andhumidi ty extremes and shock; and should requirelittle maintenance.

A study (Ref. 15) of several possiblefield instruments was carried out in 1969 bythe Northeastern Radiological Health Laboratory,U.S. Public Health Service. Four ionizationchambers and four Geiger-Muller counters werestudied. Calibrations were performed in thelaboratory, followed by determinations of theminimum detectable concentrations. Some ofthe instruments were then used in the fieldaround a fuel-reprocessing plant, to determineperformances under actual field conditions.

None of the field instruments came closeto the sensitivity required for backgroundmeasurements in the pCi/m 3 range. However, allwere sensitive enough to measure fractions ofthe MPC for individuals in the general public(300,000 pCi/m3).

(i) Flow-through Ionization Chambers

The four flow-through ionizationchambers were tested in the laboratory usingdry, radon-free air. They ranged in size from0.5 to 4.3 liters in volume. After calibrationagainst an NBS standard (Ref. 7), the minimumdetectable concentrations ~, defined inReference 15 as twice the standard deviationin counting) were determined: they ranged from130,000 to 40,000 pCi/m 3 • The calibrationswere performed with errors (20) in the ±7% to

±l7% range. These ionization chambers haveseveral undesirable properties: first, theymust be used downstream of a radon holdup trapand filter (or equivalent). Second, becauseof the use of the radon trap, the averagingtime is in the 30-minute range, which is muchlonger than the few-minute time for a significant change in 85Kr concentration when afuel-reprocessing-plant plume passes directlyoverhead. Third, it is necessary to makeappropriate measurements of pressure, temperature, humidity, and external backgroundvariation to obtain reasonable accuracy.Finally, maintenance requirements are high.To quote from Reference 15:

"It should be noted that althoughthe ionization chamber systems can bemade to operate in the field, the degree of care, number of precautions,and amount of operator training required to obtain usable data for environmental levels, and the questionable nature of the data obtained whenthe field levels passing the instrument are fluctuating rapidly, allweight heavily in favor of usingsimpler systems for this purpose."

(ii) Geiger-Muller Counters

In Ref. 15, several Geiger-Muller(G-M) tubes were also studied. These werecalibrated against the flow-through ionizationchambers described above, and then minimumdetec~able concentrations were determined.The calibration errors (20) were in the ±13%region for all of the G-M detectors. Themost sensitive G-M detector was found to bethe Eon 8008H, a double end-window pancakedetector, of 2" diameter with 3.5 mg/cm2

mica windows. It had an MOC of 12,000 pCi/m3

with a counting time of 10 minutes (sample)and 10 minutes (background). Unfortunately,this detector was so fragile that its use inthe field was precluded.

The other G-M detectors all had MDC's inthe region of about 25,000 pCi/m3 • These instruments were an Amperex 18546 and an Eon800lT (both one-window pancake detectors of2" diameter); and an LND 719 and an Eon 5l08E(both cylindrical ~robes, 5-1/2" long, 0.6"diameter, 30 mg/em wall thickness). Thecylindrical instruments were found to be durable against mild shock and rain in the field;the single-window detectors were less durableagainst shock. However, all performed in thefield with sensitivities nearly identical tothose measured in the laboratory. The conclusion can be taken directly from Ref. 15:

"Long-term (weeks to months)environmental monitoring would demand the most sensitive detectorsand systems that could endure the

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MONITORING


(2)

environment with a minimum ofattention. The choice at presentis between the single windowedpancake tube (Amperex 18546)and the thicker walled (3Omg/cm2)

cylindrical probes (Eon 5l08Eor LND 719) which, though slightlyless sensitive, are certainlythe most durable of the detectorsevaluated."

4. SUMMARY AND CONCLUSIONS

Two important numbers determine the sensitivity required of instruments for measuring85Kr in environmental air:

1. the maximum permissible concentrationfor individuals in the general publicis 300,000 pCi/m 3 (Ref. 5, 6).

2. the typical "background" level of85Kr in air today is in the range10 to 15 pCi/m 3 (Ref. 3).

The ideal instrument is one capable ofmeasuring the background level to a small fractional accuracy; several of the laboratory techniques described have this sensitivity. Thesetechniques, which use liquid or plastic scintillation counting, all suffer from a commonproblem: a complicated series of laboratorysteps is required to concentrate the kryptonfrom the original gas sample.

In contrast, the field monitoring instruments (Ref. 15) are all several orders of magnitude less sensitive, with MDC's ranging from12 000 to 28,000 pCi/m 3 (for the G-M detectors)and from 39,000 to 190,000 (for the ion chambers).All of these instruments are thus capable ofdetecting 85Kr at levels well below the 300,000pCi/m 3 MPC for individuals in the general public,but cannot measure 85Kr in "background" samples.

At present, there does not exist (to ourknowledge) a commercially available Krypton-85Monitor which can be purchased off-the-shelf.The G-M detectors described in Ref. 15 areworthy of commercial development, to meet theneed for monitoring in the field around fuelreprocessing plants and nuclear power reactors.Any commercial instrument would have to satisfyseveral requirements besides sensitivity:

(1) Rugged construction, insensitivityto changes in temperature andhumidity.

Some method of continuous recordingof the data: at least a strip-recorder, or preferably a directmagnetic-tape record.

(3) Some method of calibration:perhaps a frequent, rapid check

with a high energy source,and a less-frequent check ina controlled chamber of known85Kr concentration.

For the more sensitive measurements oflevels below the natural background of a fewpCi/m 3, field instruments are presently outof the question. Some kind of cryogenic concentration method is required to increase thespecific activity to the point where re~sonable

counting times (~ a few hours) are posslble.

One key problem here is with the. accuracyand reproducibility of the concentratlonmechanism. Accurate determinations of thefractional yield through a multi-stage sequenceare notoriously difficult. This is trueespecially if a known volume of "ordinary"krypton is introduced as a carrier, sinceall krypton today unfortunately contains 85Krat levels in the ppm region. One solution isthe use of 83mKr as a tracer to determine theyield.

There are a few technological developmentson the horizon which will provide some increasedsensitivity. The most important of these isthe recent development of substantially betterphotomultiplier tubes (Ref. 16). These tubeshave higher quantum efficiency, lower noise,and generally superior operating characteristics.This will improve the scintillation countingmethod considerably.

The incorporation of integrated circuitelectronics into the G-M detector systems willalso be important, helping to increase theruggedness and reliability of the technique.Also, read-out systems are being developedwhich will enable the data to be collected,recorded, and analyzed remotely, bypassingthe strip-chart-recorder step entirely.

Finally, it should be noted that some ofthe instruments designed to measure tritiumin environmental samples are also capable(or adaptable) for the 85Kr problem, withsome modifications and changes in procedure.The reader is referred to the "Tritium" sectionelsewhere in this volume for details.

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5. REFERENCES


( 1

V

1. "Siting of Fuel Reprocessing and Waste Management Facilities,"Report ORNL-445l, Oak Ridge National Laboratory, Oak Ridge, TN 37830 (July 1971).

2. W.S. Diethorn and W.L. Stockho, ''The Dose to Man From Atmospheric Krypton-85,"Health Physics 23, 653 (1972).

3. N.I. Sax, J.D. Denny, and B.R. Reeves, '~odified Scintillation CountingTechnique for Determination of Low Level Krypton- 85," Anal. Chern. 40, 1915 (1968).

4. J. Mantel, ''The Beta Ray Spectrum and Average Beta Energy of Several Isotopesof Interest in Medicine and Biology," Int. J. Appl. Radiat. Isotopes 23, 407 (1972).

5. ICRP Publication 2, "Permissible Dose for Internal Radiation," InternationalCommission on Radiological Protection. Pergamon Press, New York, NY (1959).

6. U.S. Atomic Energy Commission, 10CFR20 (Code of Federal Re~lations, Title 10,Part 20), "Standards for Protection Against Radiation," Appendix B, Table II,"Concentrations in Air and Water Above Natural Background."

7. National Bureau of Standards, NBS Standard #204, 10/9/62, 60.8 x 106 dps/gram-mole.

8. W.F. Linke and A. Seidell, "Solubilities of Inorganic and Metal Organic Compounds,"Vol. II, 4th ed., American Chemical Society, Washington, DC, p. 342 (1965).

9. R.E. Shuping, C.R. Phillips, and A.A. Moghissi, "Low Level Counting of EnvironmentalKrypton-85 by Liquid Scintillation," Anal. Chern. 41, 2082 (1969).

10. D.L. Horrocks and M.H. Studier, "Determination of Radioactive Noble Gases with aLiquid Scintillator," Anal. Chern. 36, 2077 (1964).

11. M.L. Curtis, S.L. Ness, and L.L. Bentz, "Simple Technique for Rapid Analysisof Radioactive Gases by Liquid Scintillation Counting," Anal. Chern. 38, 636 (1966).

12. S.L. Cummings, R.L. Shearin, and C.R. Porter, "A Rapid Method for Determining85Kr in Environmental Air Samples," p. 163 of Rapid Methods for Measuring Radioactivit in the Environment, Proceedin s of a Conference, 5-9 Jul 1971,International Atomic Energy Agency, Vienna 1971 .

13. A.A. Moghissi and H.B. Hupf, "A Krypton-83m Generator," Int. J. Appl. Radiat.Isotopes~, 218 (1971).

14. D.L. Stevenson and F.B. Johns, "Separation Technique for the Determination of85Kr in the Environment," p. 157 of Rapid Methods for Measuring Radioactivityin the Environment Proceedin s of a COnference 5-9 Ju1 1971, Internatlona1Atomic Energy Agency, Vienna 1971 .

15. D.G. Smith, J.A. Cochran, and B. Shleien, "Calibration and Initial FieldTesting of 85Kr Detectors for Environmental Monitoring," Report BRH/NERHL70-4, U.S. Public Health Service, Northeastern Radiological Health Laboratory,109 Holton Street, Winchester, MA 01890 (Nov. 1970).

16. B. Leskovar and C.C. Lo, "Performance Studies of Photomultipliers Having Dynodeswith GaP(Cs) Secondary Emitting Surface," IEEE Trans. Nucl. Science, NS-19 (3)p. 50 (1972).

1.:

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.~_) 0 )

STRONTIUM-90 AND -89

RAD-NUCStrontilDTIJune 1973Page 1

1. Introduction

2. Sources of Enivrorunental RadiostrontilDTI


a. Introductionb. COlll1tingc. 90Sr/89Sr Separation

4. Chemical Techniques

a. Airb. Waterc. Milkd. Other Mediae. YttrilDTI Recovery after Ingrowthf. Interferencesg. Calibration Techniquesh. Quality Control

5. SlDTImary and Conclusions

6. Acknowledgment

7. References

,j ,.,j

I

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RAD-NUCStrontiumPage 3

1. INTRODUCTION

There are only two radioactive isotopesof strontium of significance in radiologicalmeasurements in the environment: strontium-89and strontium-90.

544100

rr

Energy keV 2210

% Emission 100

Type of rremission

Energy keV

% Emission

Type ofemission

Particle energy, MeV

Particle energy, MeV

spectrum of beta energies from decayof yttrium-9D (from Ref. 1).

5r90Avg. ~ energy 196-1 keV

Y 90Avg. {3 energy 933·5 keV

o

40

60

20

%40

FIGURE 1. spectrum of beta energies from decayof strontium-9D (from Ref. 1).

FIGURE 2.

100,000

l68-hour-weekOccupationalMPC in water(pCi/liter)

1,000

10,000

100

l68-hour-weekOccupational

MPC in air(pCi/m3

)Isotope

Strontium-9D is the more significantfrom the point of view of environmental irripact.This is due mostly to its long half-life(28.1 years). It is a pure beta emitter withonly one decay mode, leading to yttrium-90by emission of a negative beta with Emax =546 keV. Subsequently, the 90y daughternucleus almost always decays be emitting aS- (Emax = 2.27 MeV) with a 64 hour half-life,leading to stable zirconium-90. The betaenergy spectra are shown in Figure 1 andFigure 2 (from Ref. 1).

Strontium-89 has a 52 day half-life,much shorter than that of 90Sr but stillquite long in its own right. It decays bynearly pure S- emission to stable yttrium-89,the maximum beta energy being 1.463 MeV.

The main radiological impact of radiostrontium in man is due to its biochemicalresemblance to calcium. When ingested, someof the strontium becomes lodged in the bones,where it remains for a long time (almostperrnanently).Its subsequent decay producesradiation dose directly at the site (the2.27 MeV highest-energy beta of the daughter90y has a maximum range of only about 1.0g/cm2). Because of this, the recommendedmaximum permissible concentrations (MPC)in air and water are quite small. For occupational exposure, the ICRP (Ref. 2) hasrecommended the following MPC's on a l68-hourper-week basis for soluble strontium:

Strontium-89

Strontium-90

2. .SOURCES OF ENVIRONMENTAL RADIOSTRONTIUM

The maximum permissible body burdens(MPBB) are 2 ~Ci (for 90Sr) and 4 ~Ci (fora9Sr) , both for burden in the bone (Ref. 2).For individuals of the general public, theMPC and MPBB levels are a factor of 10smaller; and for a suitable average sampleof a large general population, another factorof 3 smaller still.

The two main sources of radiostrontiumare from (i) nuclear reactors. and their fuelreprocessing plants; and (ii) from falloutafter atmospheric nuclear bomb tests. Bothstrontium radioisotopes are among the importantfission products.

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In nualeap peaatoP8~ there is a significant production of both 90Sr and 89Sr. Reference 3 proj ects that the total amounts ofactivity produced annually will increasedramatically in the coming decades because ofgrowth in the nuclear power industry. In 1970the total strontium-90 annual production ratewas 4.0 megacuries/year; the projected figuresfor the years 1980, 1990, and 2000 are 227,410, and 460 MCi/year, respectively. Theintegral (accumulated) strontium-90 activitiesin those three years are projected to be 960,4600, and 9550 MCi, respectively. This isbased upon an Oak Ridge National Laboratoryprojection whose detailed input is subjectto revision, but the trend is clear. Thestrontium-89 production rates will grow similarly, although there is no long-term build-upof strontium-89 (because of its 52-day halflife).

Reactors can be designed and built sothat most of the activities in the reactorfuel do not escape into the environment. Ata reactor site itself, the average releaserates of fission products are only very smallfractions of the total fuel inventories.For example, at the Dresden Nuclear PowerStation in Illinois, the ratios of releasedto produced activities in 1968 (Ref. 4) were4 x 10- 9 (for strontium-90) and 6 x 10- 8(for strontium-89). The average releaserates in stack effluent were 700 pCi/second(strontium-89) and 3 pCi/second (strontium90), while in liquid effluent the numberswere 8000 and 900 pCi/second, respectively.

The potential source for environmentalrelease is mainly the nuclear fuel-reprocessing plants (see "Fuel Reprocessing" elsewhere in this Volume), where the fuel rodsare dissolved and the radiostrontium isreleased from the cladding. However, sufficient precautions have been designed into themore recent plants to assure practically complete containment in normal operation. Forexample, the ISO-day storage of fuel elementsbefore reprocessing allows 86% of the 89Srto decay (but only 1% of the 90Sr). At theMidwest Fuel Recovery Plant in Morris,Illinois, the design calls for no environmental release of radioactive waste in eithersolid or liquid form. A limit on emissionsof gaseous gross beta (particulates in air)at 7.0 ~Ci/second has been suggested (Ref. 5),based upon strontium-90 as the limitingradionuclide. From this it can be seen thatthe total environmental emissions should besmall indeed.

Fallout is, of course, the source ofradiostrontium that has gained the widestcogriizance in the minds of the general public.Indeed, strontium-90 was a household word inthe early 1960's. This widespread concern inthe era of large-scale atmospheric nuclearbomb tests led to a great deal of researchinto the environmental behavior of radiostrontium in its pathways from the nuclear fireballto man. Fallout concentrations were measuredextensively, and are still being measuredroutinely (Ref. 6). The deposition was considerable. We quote from the Federal Radiation Council (Ref. 7), "On January 1, 1963,the accumulated levels of Strontium-90 depositedover the United States varied from about 100to 125 millicuries per square mile in the 'wet'areas (areas of greatest annual precipitation)to 40 to 50 millicuries per square mile in the'dry' regions." The recent French and Chinesenuclear tests have again deposited strontium-90as fallout.

Studies of the fate of strontium-90 fromfallout have revealed that an imp9rtant measureof its impact on man is the ratio of strontiumto calcium in the total diet. "The (Sr/Ca)ratio in new bone being formed is one-fourthof that in the average diet because thE( bodyselectively discriminates against strontium"(Ref. 8). Typical 90Sr/Ca ratios in totaldiet in 1963 (Ref. 8) were 10 to 50 pCi/gram Ca(1 pCi of strontium-90 weighs about 7 x 10- 15

grams). Activities in milk were 10 to 30pCi/liter; and in flour about 40 pCi/kg.Strontium-89 in milk averaged 40 to 55 pCi/literin 1963.

These figures indicate the range of activities requiring measurement. In biologicaland food samples, fallout measurements must besensitive to a few pCi/liter of milk, andperhaps fractions of a pCi/kg of other foodssuch as vegetables and baked foods. In airparticulate samples from reactors or fuelreprocessing plants, average release rates inthe range from a few pCi/second to perhaps afew ~Ci/sec need measurement.

Finally, the standard "gross beta" measurements in both drinking water and respirable airare designed mainly to place upper limits onstrontium-90 in these media. For example,the standard method for gross-beta in drinkingwater (Ref. 9) explicitly states that a limitof 10 pCi/liter is allowed for strontium-90,but if strontium-gO is known to be absent,then from the point of view of beta activity"the water supply would usually be regarded asradiologically acceptable provided that thegross beta concentration does not exceed 1,000pCi/liter" (Ref. g).

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3.

A.

MEASUREMENT CONSIDERATIONS

Introduction

such as urine, bone, or soft tissue. Theseare discussed in Volume 4 of this Survey("Biomedical Instrumentation").

We shall discuss methods for strontium-90and strontium-89 detemination in ail', watel',milk, and othel' media. Either of two typesof measurements is conunonly required: Inone type, a quantitative measurement ofstrontium-90 specific activity (e.g., pCi/g)is made, while in the second type it is merelynecessary to detemine an upper limit of ac.tivity to assure safety. In the second type,a gross-beta measurement is usually perfomedas a first screening step, since it is easierthan elaborate strontium-isolation chemistry.Only when the gross-beta measurement exceedsguidelines, or when a strong suspicion ofstrontium contamination is present, is specific strontium analysis called for.

Here we shall concern ourselves predominantly with the quantitative analysis ofradiostrontium specific activity in variousmedia. Because strontium must be determinedat activity levels well below the permissiblegross-beta levels in strontium's absence,radiochemical separation techniques are invariably required.

There is an extremely wide variety ofmethods for radiostrontium, but all follow asimilar outline: chemical aonaentl'ation,followed by pupifiaation and sample pl'epaT'ation,followed by aounting.

Chemical techniques for radiostrontiumhave been tailored to the requirements ofthe various media to be measured. Since thechemical properties of yttrium play nearlyas important a role as those of strontiumitself, the procedures have generally dependedupon multiple-step separations of yttrium aswell as strontium from the bulk material.Also, media containing the radiostrontiums arefrequently contaminated with radioactivecesium-137 (also a long-lived beta emitter),iodine-13l, and perhaps other radionuclidesas well, so that the radiochemistry can becomplicated.

Here we shall give separate treatmentsto the various media: air, water, milk, andother media (principally foodstuffs and soil).The separate treatment is necessary becauseof the differences in the chemical techniques:for example, in both milk and urine yttriumfoms an anionic complex which makes possibleits separation by direct anion exchange. Inair filters, the chemical techniques are quitedifferent.

We shall not treat here measurements ofstrontium-90 activities in biomedical samples

B. Counting

Beta counting is ultimately required inany of the methods. The final strontiumsample has to be prepared properly for counting:for most of the counting instruments it mustbe a thin sample distributed reasonably uniformly over an area compatible with the instrument.

Counting is done with any of a number ofinstruments. Typical instruments includeinternal (or external thin-window) gas proportional counters; G-M tubes; semiconductordetectors; and less frequently liquid orplastic scintillation counters, which requiredifferent sample-preparation methods. Theproblems and differences which characterizethe various beta counting techniques havebeen discussed elsewhere in this Volume ("BetaParticle Instrumentation") and will not berepeated here.

C. Strontium-90/Strontium-89 Separation

The chemical separation techniques cannot,of course, separate the two strontium radioisotopes from each other or from stablestrontium. Consequently the end product ofthe chemical separation contains all strontiumisotopes, including carrier strontium and insome cases strontium-85 added as a tracer forchemical yield.

Separation of strontium-89 from strontium90 is perfomed using one of two methods.The first is beta speatl'ometl'Y, which reliesupon the differences in the maximum energiesof the beta spectra (Emax = 1.463 MeV forstrontium-89; Emax = 546 keV for strontium-90;and Emax = 2.27 MeV for yttrium-90). Thistype of measurement is not well suited tothe cases in which the strontium-89/strontium90 ratio is either very large or very small.

The most commonly used spectrometrytechnique employs a succession of differentabsorbers to count selectively the highestenergy betas (yttrium-90). If yttrium hasbeen separated out chemically, the strontium89 betas are counted. Detection efficienciesmust be calibrated using known activities ofthe individual radionuclide species (or foryttrium-90 an equilibrium mixture of strontium-90 and yttrium-90); since geometricaleffects can produce quite wide variations, itis not safe to rely upon calculations of thefractional detection efficiency. Althoughthis problem is most important in betaspectrometry, it holds as well for the

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RAD-NUCStrontiwnPage 6

90Sr: 26 pePl.9Sr: 21 pePl

Correct values

Measured values

90Sr: 27.7 ± 3.7 pePl.9Sr: 24 '" 2 6 pePl90 y : 3.27'" 1.8 pePl

..............

....'"

'. ' ..

.".::::::::.:::;':~:~"""'''''':::::;::::'~::::::~.':'':' . ..: ......:~. .' .

.;~~~:~~_~.:. __A~,,",=,~::~;~;~;~,,;;.;,,"~._~ .FIGURE 3. Beta pulse height spectm (from Ref. U).

PCPL = pCi/liter

4. CHEMICAL TECHNIQUES

J..- Total Activity- f------"

AtrontiuL90

y -I/Ytt~ium.90

I

/I

2°0 3 6 9 12 15 18 21Time-days

~ 70I

"". 50

~

100

200

.150

FIGURE 4. Yttrium-90 VS. strontium-90activity as a function of time.(from Ref. 9)

Measurements of "total radiostrontium"usually refer to the total activity of a strontium fraction immediately after yttriwn isseparated chemically. The time elapsed beforecounting is critical, of course, because afterstrontium-90 and yttriwn-90 reach parentidaughter equilibrium the "gross beta" countingrate represents exactly twice the activity ofthe parent strontium-90 itself.

A good summary of the various types ofchemical separation techniques has been givenby Bowen (Ref. 13). We shall quote from hiswork extensively below. In the quotation,Bowen refers to sea-water measurements, but hiscomments should apply to other liquids. Hebegins by discussing two attempts to extractyttrium-90 directly from environmental samples,using thenoyltrifuoroacetone (TTA) in benzene.He continues as follows:

determination of beta spectral efficiency inany of the methods being described.

The beta spectroscopy technique whichshows the most promise is liquid scintillationspectroscopy, since after the sample is dissolved or suspended in a scintillator thegeometrical efficiency factors are well understood. Direct counting of a sample with' liquidscintillators suffers from severe limitations(Ref. 10). However, Pil tingsrud and Stencel(Ref. 11) have described a technique whichfirst separates strontiwn chemically as carbonate, using methods to be described later inthis discussion. The SrC0 3 is then suspendedin liquid scintillator using a gelling agent,and counted, typically for 2 to 12 hours,using a Packard 'Tri-Carb' system and a 512channel analyzer. (See "Tritiwn" elsewhere inthis volwne for details.) For a l2-hourcounting period, the minimwn detectable activity is about 1 pCi. A typical spectrwn isshown in Figure 3; the unfolding of the threeisotopic spectral shapes (90Sr , 90y, 89Sr)is done by computer. Another application ofthis technique is that of Kamada et al. (Ref.12), who give detailed des~riptions of the waythe beta spectrwn is unfolded.

The second, and today the more commontechnique for strontiwn-89/strontiwn-90separation uses the ingrowth of the daughteryttrium-90. Figure 4 (from Ref. 9) shows themanner in which yttriwn-90 and (yttriwn-90 +strontiwn-90) activities grow in time from apure strontiwn-90 sample. Counting rates (corrected for efficiency) can be compared fromtwo measurements, the first immediately afterstrontiwn chemical separation (within a fewhours, say) and the second 3 to 6 days later.Alternatively, chemical separation of theyttrium daughter can be performed after allowing for ingrowth. Both techniques are frequently used.

\.~) !.~i 't ) t.;:.l ",) 0 :1

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, )"-.-.

"With the exception of these twoventures, all the procedures knownto us for strontium-gO analysis inthe oceans depend on the separationof most of the strontium, togetherwith more or less of the calciumfollowed by removal of all or mo~t ofthe calcium and then by decontaminationof the strontium fraction from othernatural or artificial radionuclidesby a series of ferric hydroxide andbarium chromate scavenges; the cleanedstrontium, usually after precipitation with annnonium carbonate for convenience, is then stored for enoughtime to allow yttrium-90 to come againto equilibrium with its parent, twoweeks being a convenient time; yttrium90 is separated with a minimtnn amountof iron, samarium or yttrium carrier,often wi0 some ~ddi tional scavengingsteps, flnally flltered, weighed andmounted for beta counting. Countingh~s been ~one u~ing a variety of gasfllled Gelger-Muller or proportionalcounters, or with solid plastic betascintillator. The amount of dataobtained to confirm the shape of theexpected 64-hr half-life decay curvehas varied widely, in response largelyto economic factors; although 'goodradiochemical technique' dictates theuse of repeated milkings of yttrium-90 and insistence on superimposabledecay curves, this has been a nicetyoften omitted.

"In such a separation scheme, thenumber of variations available is notlarge:

"(a) Strontium may be initiallyprecipitated as carbonate or as oxalate[Ref. l3b,c] and for the carbonateprecipitation, sodium carbonate [Ref.l3d, e], sodium carbonate plus ammoniumchloride [Ref. l3f], or ammoniumcarbonate [Ref. l3g] may be used.Although other reagents have beenproposed: manganese dioxide by Shipman[Ref. l3h] or coprecipitation withrhodizonic acid, we know of no datareported to have been obtained bythese or any other separation processes than those cited above.

" (b) The oxalate precipitate maybe decomposed by dry ignition [Ref. l3e]or by wet combustion with nitric acid.

"(c) Strontium may be separatedfrom such calcium and magnesium asaccompany it in the initial precipitation by:

. "(1) Selective complexation precipitatwn, followed by fuming nitric acidprecipitations to obtain pure strontiumnitrate [Ref. l3d, fl.

"(2) Oxalate reprecipitation,followed by fuming nitric separations(Shvedov and Ivonova, referred to in[13f]) .

"(3) Nitric acid precipitationswithout other treatment (cf. Ref. [13c, e];many others).

"(4) Selective elution serially,from cation exchange columns [Ref. l3a].

"(d) The overall chemical yieldof strontium in the separation proceduremay be determined gravimetrically [Ref.l3b], by counting tracer strontium-8S(e.g., Ref. [13c]) by flame photometry oratomic absorption spectrophotometry orvolumetrically [Ref. 13a). '

."(e) The final separation of daughteryttnlJl!l-90 may be made using ferrichydrox~de [Ref. l3d, e, f] or yttriumhydronde [Ref. l3c), or samarium hydroxide.In each case the choice has been basedon ~he availabi~ity - or ease of preparatlon - of radlochemically pure carrierand of the physical properties of itsdried hydroxide as a counting medium."

A. Air

In air, measurements of radiostrontium arenearly always made by examining particulatematt:r. The sampling t:chnique is relativelystralghtforward: partlculate matter iscollected on a high-efficiency filter in a HiVol sampler. Air sampling rates of 1000 m3/dayare typical.

Chemical separation is required becauseof ~he no:mal l?resence of other beta-emitting .radlonuclldes In the particulate matter: forexample, naturally-occurring radon daughtersc~n adhere to par~i~ulate matter and produceslzeable beta actlvlties. The compilation ofMethods of Ail' Sampling and AnaZysis (Ref. 14)recen~ly lssued.by the Intersociety Committeecontal~s tentahve meth?ds for measuring bothstrontlum-90 and strontlum-89 in air. Thechemical separation is the same for both radiostrontium isotopes, and this method is likelyto be adopted as a "standard Method" in thenear future.

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The filter is ashed in a muffle furnaceprior to the chemical procedure. We quotefrom Ref. 14:

"Strontium is separated fromcalcium, other fission products, andnatural radioactive elements. Nitricacid separations remove the calciumand most of the other interferingions. Radium, lead, and bariumare removed with barium chromate.Traces of other fission productsare scavenged with iron hydroxide.After the strontium-90 + yttrium-90equilibrium has been attained, theyttrium-90 is precipitated as thehydroxide and converted to the oxalatefor counting. Strontium chemicalyield is determined gravimetricallyas strontium carbonate. 0.5 pCistrontium-90 can be determined bythis method with an error of lessthan ±10% at the 95% confidencelevel under uspal conditions (counterbackground of less than 1 cpm anda 60-minute count)."

Another technique for air filters hasbeen developed at Atomic Energy of CanadaLimited (A.E.C.L.) (Ref. 15). The firststages of the separation are described asfollows:

"The ashed air filter is fumedwith hydrofluoric and perchloricacids to remove silica. After extraction with nitric acid and fusion withsodium carbonate, an anion exchangecolumn is used to separate plutoniumfrom iron and other elements. Thecolumn effluent is retained for theestimation of barium (140), strontium(89, 90) and cesium (137)."

An alternative separation method, alsodescribed in the A.E.C.L. Manual (Ref. 15),is applicable when the ashed air filters contain little acid-insoluble.material. Inthis method, "plutonium is separated frombarium, strontium, and cesium by hexone extraction from a saturated ammonium nitratesolution" (Ref. 15). Hexone is methyl isobutyl ketone. This method is shorter andeasier than either of the others mentioned,making it attractive where the conditions forits use are applicable. Use of either A.E.C.L.separation method must be followed by anotherstage to isolate radiostrontium from bariumand cesium.

B. Water

Two types of water are of most concern:Drinking water and waste water. We have alreadyreferred above to the U.S. Public Health ServiceDrinking Water Standards (Ref. 16). The limitfor strontium-90 is 10 pCi/liter, when othersources of intake are not considered. No

explicit limit is given for strontium-89, butthe maximum permissible level for it would besignificantly higher: for example, theICRP's maximum permissible concentration forstrontium-89 in water is a factor of 100higher than for strontium-90.

In Stanc1a:f'd Methods (Ref. 9) the methodfor total radiostrontium and strontium-90in water applies to either drinking water orfiltered raw water. We quote from Ref. 9:

"It is applicable to sewage andindustrial wastes, provided that stepsare taken to destroy organic matterand eliminate other interfering ions.In this analysis, a known amountof inactive strontium ions, in theform of strontium nitrate, is addedas a "carrier". The carrier, alkalineearths and rare earths are precipitated as the carbonate to concentratethe radiostrontium. The carrier,along with the radionuclides ofstrontium, is separated from otherradioactive elements and inactivesample solids by precipitation asstrontium nitrate from fuming nitricacid solution. The strontium carrier,together with the radionuclides ofstrontium, is finally precipitatedas strontium carbonate, which isdried, weighed to determine recoveryof carrier, and then measured forradioactivity. The activity in thefinal precipitate is due to radioactive strontium only, because allother radioactive elements have beenremoved•••.

"Radioactive barium (140Ba, 140La)interferes in the determination ofradioactive strontium lllasmuch as itprecipitates along with the radioactive strontium. This interferenceis eliminated by adding inactivebarium nitrate carrier and separatingthis from the strontium by precipitatingbarium chromate in acetate buffersolution. Radium isotopes are alsoeliminated by this treatment ...•

"Two alternate procedures aregiven for the separation of gOy. Inthe first method, gOy is separated byextraction into tributyl phosphate fromconcentrated nitric acid solution. Itis back-extracted into dilute nitricacid and evaporated to dryness forbeta counting. The second method consists of adding yttrium carrier, separating by precipitation as yttrium hydroxide, and finally precipitating yttriumoxalate for counting."

A similar technique, not identical in allrespects but following the same general lines,is described in the A.E.C.L. Manual (Ref. 15).

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C. Milk

Milk is one of the most important pathways to man for environmental strontitnn. TheU.S.P.H.S. Pasteurized Milk Network has developed a standard analytical procedure (Ref. 1822) which will be discussed here as typical ofseveral other methods. The method removesstrontitnn (and other alkaline and alkaline earthions) by passing a liter of milk through acation exchange resin, followed by removal ofyttritnn in an anion exchange resin.

We quote from Ref. 20:

"The procedure consists ofstoring the milk samples with formaldehyde preservative for the ingrowth of the yttritnn-90 daughterof strontitnn-90, adding yttritnncarrier, and then passing the milkconsecutively through cation andanion exchange resin columns.The alkaline earth ions in milkare replaced by soditnn ions in thecation exchange column, after whichthe yttritnn is retained as an anioniccomplex - probably of citrate - inthe anion exchange column. The effluent milk is discarded and the yttritnncomplex on the anion exchange resinis destroyed with hydrochloric acid.The yttritnn, eluted with the acid,is precipitated as the oxalate, andthe radio-yttritnn is measured witha low-background beta counter ....

Initially, the maximum yttriumyield was 65% and average yieldswere 55%. Yttrium retention on theresin was improved from 80 to 90%by adding sodium citrate to the milk.The per cent eluted in 35 ml ofhydrochloric acid was increasedfrom 81 to 96% by decreasing theamount of anion exchange resin andby thoroughly stirring the resinduring elution. Other loss~s

were minimized by small proceduralchanges, so that the overall average yield was increased to 86%."

The U.S. Public Health Service manual(Ref. 21) describes other methods for milkanalysis. Their "reference method", usedmainly for quality control, is not applicablefor routine analysis. The method uses strontium-85 as a tracer; strontium is separatedby successive carbonate precipitation andHN03 washing, and the yttrium-90 ingrowthoccurs in solution. The special feature isseparation of ingrown yttrium from contaminating lanthantnn-140 using tributyl phosphate.A similar method is described in the PY'ocedUY'esManual of the USAEC Health and Safety Laboratory(Ref. 32).

Another method in the U.S.P.H.S. manual(Ref. 21) removes milk proteins by precipitationwith trichloroacetic acid (TCA); precipitatesthe alkaline earths as oxalates, subsequentlyconverted to nitrates; and separates strontiumfrom"calcium by solubility. When working inhumid climates, care is required since the sample is counted as strontium nitrate on a stainless steel planchet, which can corrode thecounting chamber if nitric acid is formed athigh humidities. The Handbook of the Environmental Protection Agency's National Environmental Research Center (Las Vegas) (Ref. 24)describes a method very similar to this last(TCA) technique.

D. Other Media

Chemical separation techniques have beendeveloped for a wide variety of media besidesair, water, and milk. The techniques are asvaried as the problems, since media such asfood or biological samples can have any of alarge number of (radioactive or stable) impurities. Here we shall only mention briefly afew methods.

In most biological samples, the firstprocedure is to convert the sample to ashin a muffle furnace (500° to 800°C). Thiseliminates the large organic substrate, whichmight originally contain strontium or yttriumin complexed form. Ashing is also performedon milk and bone samples. For some samples,which are volatile at dry-ashing temperatures,it is preferable to perform wet ashing withnitric acid, followed by an equal-volume mixture of perchloric and nitric acids (Ref. 25).The U.S.P.H.S. manual (Ref. 21) contains goodoutlines of the procedures for both dry andwet ashing.

Fusion is used for those samples (e.g.,soil, silt) which are not easily dissolved byacid digestion because of their high silicacontent. The fusion procedure in the U.S.P.H.S.manual is typical: the sample, with carrierplus 5 g of NaOH pellets per gram of sample,is fused over a Meeker burner for 20-30 minutes.Then 0.5 g of anhydrous Na2C03 per sample gramis slowly stirred in and heated again. Themelt is cooled, taken up in water, centrifuged,heated again after 3N Na2C03 is added and centrifuged again. The precipitate is dissolvedin 6~ HCl, ready for analysis (Ref. 21).

Once ashing or fusion has provided adissolved sample, the radiochemical methodsare quite similar to those already described.There are some differences, but we refer thereader to the appropriate references for details.

The U.S.P.H.S. manual (Ref. 21) containsradiostrontium techniques for urine, bone,bone ash, tobacco, vegetation, soil, and silt.

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The A.E.C.L. manual (Ref. 15) has techniquesfor animal and fish flesh, cereals, eggs, fats,and various vegetation as well as bone. TheHASL Procedures Manual (Ref. 22) containsmethods for vegetation, tissue, soil, and urine.The British A.E.R.E. has published radiostrontium methods in bone ash, milk ash, vegetablematter, human teeth, and soil (Ref. 26). Porteret al. (Ref. 27) have developed a method usingexcess ethylenediaminetetraacetic acid (EDTA)which is applicable in samples with verylarge calcium/strontium ratios, yet stillpermits strontium yield (as carbonate) to bedetermined gravimetrically. It has been usedfor a wide variety of organic media. Finally,Baratta and Reavey (Ref. 28) have describeda method used by the U.S. Food and Drug Administration for food and other biological samples,which uses tributyl phosphate extraction andanalysis of yttrium-90.

This is only a partial list of the manyradiochemical analysis techniques in the literature; for more complete coverage, the readeris referred to the literature cited. Also,as mentioned above, radiostrontium assay inbiomedical samples is treated in Volume 4("Biomedical") in this Survey.

E. Yttrium Recovery after Ingrowth

The chemical separation of radiostrontiumis often followed by ingrowth of yttrium-90,yttrium separation, and counting of yttrium-90.This method is especially useful to determinestrontium-90 in the presence of strontium-89.

One critical parameter is the specificityof this yttrium-90-separation scheme forstrontium-90. This specificity has been studiedby Goldin et al. (Ref. 25), whose procedure,after purifying SrC0 3 precipitate, is describedas follows:

"After ingrowth of yttrium,the strontium carbonate precipitateis dissolved with hydrochloricacid, neutralized to methyl orangewith ammonia, and buffered at pH 5.The yttrium is extracted into 2thenoyltrifluoroacetone solution.After the organic phase is washedwith water buffered at pH 5, theyttrium-90 is stripped by extraction with IN hydrochloric acid. Thehydrochloric acid extract is evaporated on copper planchets, heatedthoroughly to destroy residual 'organic matter, and counted, correcting for decay of the yttrium-90between its extraction and thecounting time."

The yield of strontium-89 is very smallin this procedure: only 4 x 10- 4 of the

strontium-89 is counted as yttrium-90, whilethe strontium-90 yields are typically 85% andthe yttrium yield in the solvent extraction isgreater than 95%.

Proper analytical procedure demandsthat calibrations be taken periodically tocheck the 64-hour ha:-lf-Zife of yttrium-90measured from the final yttrium sample. Thishalf-life is in the range where such measurements are easy, yet they are omitted in somelaboratories for reasons of economics orinconvenience. This check is one of the easiestways to exercise internal quality control ona modest scale.

F. Interferences

l~en chemical separation is performed,the main interferences in environmentalsamples are stable calcium, barium-140, andstable phosphates. The chemical considera-tions have been well discussed by Goldin, Veltenand Frishkorn (Ref. 25), from whom we quote:

"Calcium. Strontium as an alkalineearth element is chemically similarto the other members of this family.Its resemblance to calcium, barium,and radium is especially marked.Calcium, which is widely distributedin nature, is one of the inert elementswhose separation from radiostrontiumhas been most studied. Such separation is necessary if the strontiumradiations are to be measured directlyin samples of moderate or high calciumcontent, or if the final precipitateis weighed to determine the chemicalrecovery of strontium. Occasionallycalcium is present in such largequantities as to give unmanageableamounts of precipitate unless it isremoved.

"The precipitation of strontium(and barium) nitrate in concentratednitric acid also separates strontiumfrom calcium. The concentration ofnitric acid is critical, as too dilutea nitric acid solution will solubilizetoo much strontium, while too stronga nitric acid will precipitate calcium with the strontium. The mostfavorable range is from 65 to 75%nitric acid. Concentrated nitricacid will suffice. If the sample isin aqueous solution, fuming nitricacid probably will be needed to takecare of the dilution ....

"Barium and Radium. The fissionproduct barium-140, also a member ofthe alkaline earth group, is carriedalong with strontium as carbonate.

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It must be removed whether the strontiumor its daughter is to be counted, asthere is a radioactive daughter, lanthanum-140, which will contaminate theyttrium. It is precipitated, with carrierbarium, as chromate from a solutionbuffered at pH S. Radium, which followsbarium in this procedure, can bedetermined, although rather crudely,by alpha-counting the barium chromateprecipitate ....

"Phosphates. Phosphates interfereby causing precipitation of strontiumwhen the solution is made basic in thehydroxide scavenging step. Althoughthe phosphate content of water is usuallytoo low to be of consequence, thisinterference is very troublesome inthe analysis of biological samples,whose ash is largely calcium phosphate.Phosphates are removed in the nitricacid treatment already described,being converted to phosphoric acid,which is removed with the supernate.Several treatments usually are necessaryto ensure complete removal."

G. Calibration Techniques

There are a number of problems in performing accurate measurements using the chemicaltechniques discussed above. Among them arelosses of radiostrontium, losses of yttrium,and counting errors.

The use of standard radiostrontium preparations can help to reduce counting efficiencyerrors. The detection efficiency over thespectrum of strontium-90 (and it daughteryttrium-90) must be understood, and for thispurpose low-level solid SrC03 sources havebeen prepared by the USAEC Health and SafetyLaboratory (Ref. 29) by dilution of primarysources from the National Bureau of Standards.Standard sources for strontium-90 in milkhave also been prepared (Ref. 30).

Chemical yields can be studied usingstrontium-8S as a chemical tracer: it decays(T 1/2 = 64 days) by electron capture followedby emission of a S14-keV gamma ray. Its routineuse is uncommon partly because of its ownintrinsic radiological hazard, but it servesa valuable function in periodic quality control.Other methods for determining chemical yieldrely on classical chemical techniques, such asgravimetric measurements of carrier strontiumor of possible interfering radionuclides.

Another qual ity control measurement,mentioned above, is the observation of yttrium90's 64-hour half-life in counting of theyttrium fraction.

As in any analytical procedure, much ofthe success of radiostrontium assay dependsupon the care of the analyst ... an obviouspoint but one which cannot be overemphasized.

H. Quality Control

Quality control is one of the mostimportant elements of any radionuclide-analysisprogram. Unfortunately, quality-control checkshave usually revealed significant variationsamong laboratories analyzing for 90Sr at lowlevels. These variations are a cause forconcern since they demonstrate the fundamentaldifficulty in making routine, reliable, accurate 90Sr measurements in environmental media.

We shall discuss one recent study as anexample .. , others show comparable results.In 1971, the EPA Office of Radiation Programscarried out a study of analysis capabilitiesin milk (Ref. 31). Thirty-five participatinglaboratories made triplicate determinations ofunknown concentrations of 89Sr, 90Sr, 131I,and 137CS at activity levels (±2%) of 31, 42,69, and S2 pCi/liter, respectively. Unfortunately, nine laboratories reported resultswhose mean exceeded the 'control level' ofabout ±10% for 90Sr. [For 89Sr, 131I, and 137CSthe outlying laboratories numbered 4, 6, and2 respectively.] For many of the outlyinglaboratories in the 90Sr study, the range ofreported results for the triplicate analysesexceeded 25%. This study seems to show that,while many laboratories can perform 90Sranalyses well, a significant minority cannot.

S. SUMMARY AND CONCLUSIONS

In this section we have attempted to givean overview of the present status of radiostrontium measurements in environmental media.

Perhaps the key point to make first isthat, at the low levels which concern us here,the only methods for speaifia radiostrontiumanalysis involve analytiaal ahemistry followedby beta aounting. We have therefore emphasizedthe considerations characteristic of thechemical techniques in common use.

One difficulty in comparing differentchemical techniques is that so much rests inthe hands (and mind) of the analyst himself.A choice among the various 'commonly used'techniques may depend more on the particularequipment and skills available than on thedifferences among the techniques themselves.

This point has been made extremely wellby Bowen, from whom we quote (Ref. 13):

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RAD-NOCStrontiumPage 12

"In the extensive series of studiesof strontium-gO in sea-water choiceamong these various possibilities hasbeen made partly on the basis of prejudice, partly on economics, partly onthe basis of which other radionuclides .were to be sought on the same samples,partly on the basis of which alternative used fewest reagents known orsuspected to be significant contributors to the radiochemical blank andpartly on the basis of safety. Inmost of these variations the decis-ions have been legitimate ones, butwe feel of even more importance havebeen questions which one can stillonly describe as those of art: inthe hands even of very competent andexperienced analysts, no one method,whether of trace element or of lowlevel radiochemical analysis, appearsever to have been uniformly superiorin quality of results. For this reason,we strongly resist the suggestionthat a single 'standard' method beselected and recommended."

In support of his viewpoint, Bowen citesinterlaboratory calibration analyses in whichnearly the full spectrum of possible radiochemical procedures was represented. We quoteBowen again:

" . .. it is clear, we believe, that insuitable hands each method was capableof delivering data of high quality;it is also clear from some of theentries ... that these well-establishedmethods were capable in unsympathetichands of yielding some pretty bizarresets of numbers, indeed."

We agree with this general viewpoint.Apparently, none of the techniques suffersfrom critical intrinsic flaws; yet equallyapparently, the results obtained with a particular method seem to depend upon a specificskill of the analyst rather than upon hisgeneral competence. This situation is notsatisfactory or necessary. Much can be donein the development of these or other methodsto make them less dependent upon individualtalents.

We can swnmarize by stating first thatsensitivity is adequate in the methods commonlyused; second, that further research and development in this field is most needed in simplifying, standardizing, and automating themethods; but finally, that the market for afully automated system (even if available) isprobably insufficient to justify its development.

6. ACKNOWLEDGMENr

For this section we gratefully acknowledgethe generous advice and review of:

Edmond J. Baratta, Northeastern Radiological Health Laboratory

Patricia W. Durbin, Lawrence BerkeleyLaboratory

George A. Morton, Lawrence BerkeleyLaboratory

Claude W. Sill, U.S.A.E.C. Health ServicesLaboratory, Idaho Falls

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7. REFERENCES

RAD-NUCStrontiwnPage 13

1. J. Mantel, "The Beta Ray Spectrum and Averege Energy of Several Isotopes of Interest inMedicine and Biology', Int. J. Appl. Radiat. Isotopes 23, 407 (1972).

2. International Commission on Radiological Protection, ICRP Pub. 2, Pergamon Press, Oxford (1959).

3. "Siting of Fuel Reprocessing and Waste Management Facilities", Report ORNL-445l, Oak RidgeNational Laboratory, Oak Ridge, TN 37830 (July, 1971).

4. B. Kahn et al., "Radiological SurVeillance Studies at a Boiling Water Nuclear Power Reactor",Report BRH/DER 70-1, EPA Radiological Engineering Laboratory, 5555 Ridge Avenue, Cincinnati,OH 45213 (1970).

5. "Applicant's Environmental Report, Midwest Fuel Recovery Plant, Morris, Illinois", ReportNEDO-14504 and "Supplement 1", Report NEDO-14504-2, General Electric Company, Reactor Fuelsand Reprocessing Department, San Jose, CA 95125 (June, 1971).

6. U. S.A.E.C., "Fallout Program Quarterly Summary Reports", a series of quarterly reports availablefrom U.S.A.E.C. Health and Safety Laboratory, 376 Hudson Street, NY, NY 10014.

7. FRC Report No.4, "Estimates and Evaluation of Fallout in the United States from NuclearWeapons Tesdng Conducted Through 1962", Federal Radiation Council, Washington, DC (1963).

8. FRC Report No.6, "Revised Fallout Estimates for 1964-1965 and Verification of the 1963Predictions", Federal Radiation Council, Washington, DC (1964).

9. Standard Methods for the Examination of Water and Wastewater, 13th Edition, American PublicHealth Assoclation, 1015 - 18th St., N.W., Washlllgton, DC 20036 (1971).

10. A.A. Moghissi, "Low Level Liquid Scintillation Counting of Alpha and Beta Emitting Nuclides",Section II, part 7 in The Current Status of Liquid Scintillation Counting, E. Bransome (ed.),Greene &Stratton, NY (1970).

11. H.V. Piltingsrud and J.R. Stencel, "Determination of 90y, 90Sr and 89Sr in Samples by Useof Liquid Scintillation Beta Spectroscopy", Health Physics 23, 121 (1972).

12. H. Kamada, M. Mita, and M. Saiki, ''Measurements of 89 Sr and 90Sr in Environmental Samplesby a Low-Background Beta-Ray Spectrometer", p. 427 in Rapid Methods for Measuring Radioactivity in the Environment, Proceedings of a Symposiwn III July 1971, International AtomicEnergy Agency, Vienna (1971).

13. V. T. Bowen, "Analyses of Sea-Water for Strontiwn and Strontiwn-90", p. 93 in ReferenceMethods forMarine Radioactivity Studies, International Atomic Energy Agency, Vienna (1970).

13a. V.E. Noshkin, N.S. Mott, "Separation of Strontiwn from Large Amounts of Calciwn, with Application to Radiostrontiwn Analysis", Talanta 14, 45 (1967).

13b. Y. Miyake, K. Saruhashi, Y. Katsuragi, "Strontiwn-90 in Westem North Pacific SurfaceWaters", Pap. Met. Geophys., Tokyo 11, 188 (1960).

l3c. G.G. Rocco, W.S. Broecker, "The Vertical Distribution of Cesiwn-137 and Strontiwn-90 inthe Oceans", J. Geophys. Res. 68,. 4501 (1963).

l3d. T. T. Sugihara, H. I. James, E.J. Troianello, V. T. Bowen, "Radiochemical Separation of FissionProducts from Large Volwnes of Sea Water Strontiwn, Cesiwn, Ceriwn and Promethiwn", Anal.Chern. 31, 44 (1959).

l3e. R. Higano, M. Shiozaki, "Radiochemical Analysis of Strontiwn 90 and Cesiwn 137 in Sea Water",Contrib. Marine Res. Lab., Hydrogr. Off. Japan 1:..,137 (1960).

l3f. E.G. Azhazha, ''Methods for the Determination of Strontiwn-90 in Sea Water", RadioactiveContamination of the Sea ry. I. Baranov, L.M. Khitrov, Eds.), Akad. Nauk USSR-OceanographicCommission (1964); Trans. 1966 Israel Program Scient. Transl., US Dept. of Commerce, 177.

l3g. D.C. Sutton, 3.J. Kelly, "Strontiwn 90 and Cesiwn 137 Measurements of Large Volwne Sea WaterSamples," U.S.A.E.C. Health and Safety Laboratory, Fallout Program Quarterly SlUIlillary Rep.HASL-196 (1968).

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l3h.

14.

15

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

31.

W.H. Shipman, "Concentration of Stronti1.IDl from Sea Water by Manganese Dioxide, Determinationof Sr90 in Large Vol1.IDles of Sea Water", Rep. USNRDL-TR-995 (1966).

Methods of Air Sampling and Analysis, Intersociety Committee for a Manual of Methods forAmbient Air Sampling and Analysis. American Public Health Association, 1015 - 18th Street,N.W., Washington, DC 20036 (1972).

J.E. Guthrie and W.E. Grurnitt, ''Manual of Low Activity Environmental Analysis", Report AECL1745, Atomic Energy of Canada Limited, Chalk River, Ontario, Canada (1963).

"Public Health Service Drinking Water Standards, Revised 1962", P.H.S. Publication No. 956,U.S. Public Health Service, Washington, DC 20525.

The U.S. Public Health Service's Pasteurized Milk Network reports its radionuclide measurements periodically in Radiation Data &Retfirts. Nuclides analyzed are stronti1.IDl-89 and 90,iodine-13l, cesium-137, and barium-140. e most recent extensive discussion of its procedures is in vol. ~, pp. 731 ff. (December, 1968).

B. Kahn, G.K. Murthy, C. Porter, G.R. Hagee, G.J. Karches,-and A.S. Goldin, "Rapid Methodsfor Estimating Fission Product Concentrations in Milk", Environmental Health Series, U.S.Dept. of HEW, Public Health Service, Publication PHS-999-R-2 (1963).

C. Porter, "Rapid Determination of Stronti1.IDl-89 and Stronti1.IDl-90 in Milk", p. 11 of Ref. 18.

C. Porter and B. Kahn, "Improved Determination of Strontium-90 in Milk by an Ion ExchangeMethod", Anal. Chern. 36, 676 (1964).

"Radioassay Procedures for Environmental Samples", PHS Publication No. 999-RH-27 (1967),U.S. Public Health Service, Bureau of Radiological Health, Rockville, MD 20852.

C. Porter, D. Cahill, R. Schneider, P. Robbins, W. Perry, and B. Kahn, "Determination ofStrontium-90 in Milk by an Ion Exchange Method", Anal. Chern 33, 1306 (1961).

J .H. Harley (ed.), HASL Procedures Manual, Report HASL-300, USAEC Health and Safety Laboratory, 376 Hudson St., New York, NY 10014 (1972). Earlier editions of this manual werepublished as Report NYO-4700.

F.B. Johns, "Southwestern Radiological Health Laboratory Handbook of Radiochemical AnalyticalTechniques", Report SWRHL-11 (1970). Available from SWRHL, now EPA National EnvironmentalResearch Center, Las Vegas, NV 89114.

A.S. Goldin, -R.J. Velten, and G.W. Frishkorn, "Determination of Radioactive Strontium",Anal. Chern. 31, 1490 (1959).

A. Parker, E.H. Henderson, and G.S. Spicer, "Analytical Methods for the Determination ofRadiostrontium in Biological Materials", Report AERE-AM 101, Atomic Energy Research Establishment, Harwell, U.K. (1965).

C. Porter, B. Kahn, M. Carter, G. Rehnberg, and E. Pepper, "Determination of Radiostrontiumin Food and Other Environmental Samples", Environ. Science and Technology !.' 745 (1967).

E.J. Baratta and T.C. Reavey, ''Rapid Determination of Strontium-90 in Tissue, Food, Biota,and Other Environmental Media by Tributyl Phosphate", J. Agricultural and Food Chemistry17, 1337 (1969).

J .H. Harley, "Operation of a Laboratory Intercomparison Program", p. 92 in "Fifth AnnualMeeting of the Bio-Assay and Analytical Chemistry Group", U.S.A.E.C. Report TID-759l(1960), U.S.A.E.C. Technical Info. Div., Washington, DC.

M. Rosensteil, P.B. Hahn, and A.S. Goldin, "Interlaboratory Study of Strontium-90 Measurementsin Milk - August 1963", Health Physics 11, 966 (1965).

F. Knowles, "Interlaboratory Study of 131 1, 137CS, 89Sr and 90Sr Measurements in Milk,July 1971", Technical Experiment 71-MKAQ-l, EPA Analytical Quality Control Service, 109Holton Street, Winchester, MA 01890 (1971).

~,...f '.' .. .1 ,,) u~,.) <.J

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IODINE-13l AND -129

RAD-NUCIodineJune 1973Page 1

1. Introduction

2. Radiation Protection Guides

3. Sources of Envirorunental Radioiodine

4. Measurement Considerations: Iodine-13l

a. Airb. Milkc. Waterd. Other Mediae. Quality Control

5. Measurement Considerations: Iodine-129

a. Liquid Scintillation Countingb. Neutron Activation Analysis


7. Acknowledgment

8. References

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1. INTRODUCTION

There are two main iodine isotopes ofsignificance in radiological measurements inthe environment: iodine-129 and iodine-13l.Their properties are sufficiently differentthat they will be treated separately below.The difference is due to the physical characteristics of the decays.

These MPC and MPBB values are based upondirect ingestion of water or inhalation ofair, leading to dose to the thyroid (theprincipal site for iodine concentration inthe body). The biological half-life ofiodine in the thyroid is about 180 days(Ref. 2). The dose from iodine-13l decayingthere is mostly (~90%) from the beta emissions, not from the gammas.

2. RADIATION PROTECTION GUIDES

With the thyroid as the critical organ, themaximum permissible body burdens (MPBB) are0.7 ~Ci (131 1) and 3 ~Ci (1291), accordingto the ICRP (Ref. 1).

The ICRP' s recommended maximum permissible concentrations (MPC) of these nuclidesfor occupational exposure are as follows ona 168 hour-per-week basis (Ref. 1):

For individuals in the general public,the MPC and MPBB levels are a factor of 10smaller; and for a suitable average sample ofa large general population, another factor of3 smaller still.

The U.S. Atomic Energy Corrnnission'sregulations are set forth in the Code ofFederal Regulations, 10CFR20 (Ref. 3). Allof the ABC occupational limits are identicalto those recommended by ICRP. Recently,however, the ABC has proposed revised designguidelines which would govern the emissionsfrom light-water power reactors under itsjurisdiction (Ref. 4). If promulgated, theseguidelines would, amon¥ other changes, decrease the MPCa for 13 I in the air aroundthese reactors by a factor of 100,000. Themotivation for this large decrease seems tobe the desire to limit the 131 1 dose to aninfant thyroid to 5 mrem/year, assuming as acritical pathway the following chain: reactor/air/grass/cow/milk/infant. The cow usedin calculatin¥ the pathway would eat grassexposed to 13 I from the reactor, and theinfant would drink 1 liter of milk per dayfrom that cow.

Morley and Bryant (Ref. 7) have studiedthe case of a 6-month-old infant consuming0.7 liters of milk per day. An iodine-13lconcentration in milk of 400 pCi/liter isfound to produce a dose of 1500 mrem/year tothe child's thyroid. Using 1 liter/day consumption, this dose would be about 2100 mrem/year.

If an infant thyroid dose of only 5 mremlyear is desired, and assuming 1 liter/day consumption, the milk concentration must be onlyabout 1 pCi/liter using Morley and Bryant'scalculation. This then implies an air concentration limit of about 0.002 pCi/m3 using

Although there is still not total agreement on the concentration factors in thispathway, it is possible to reproduce thereasoning leading to the factor of 100,000.Two elements in the chain have been studied:air-to-milk and milk-to-thyroid.

Burnett (Ref. 5) has deduced an iodine131 concentration of 56,000 pCi/liter ofmilk, for an air concentration of 100 pCi/m3

(which is the MPCa for the general publicand equal to 1/30 of the occupational MPCacited above). Recent measurements by VanAsand Vleggaar (Ref. 6) find a similar value fordry deposition and about twice as high a milkconcentration when iodine is washed out ofthe air by rain.

l68-hourOccupati.onalMPC in Water(pCi/liter)

20,0004,000

3,000600

l68-hourOccuI_ational

MPC in Air(pCi/m3

)Isotope

Iodine-13lIodine-129

Iodine-129 is a beta-emitter with a17 miZZion year half-life. All of the decaysproceed by emission of a beta (Emax = 150 keY),followed by a 40-keV gamma, leading to stablexenon-129. Neither the S- nor the gamma isvery energetic, which leads to difficultiesin detection. On the other hand, even smallactivities represent sizeable weights ofiodine-129 in a material: one curie of pureiodine-129 would weigh about 6000 grams. Itis therefore possible to use a technique suchas neutron activation analysis on some iodine129 samples.

Iodine-131 has a half-life of 8.05 days.It decays by emission of one of several betasleading to excited states of xenon-13l; theexcited states then decay to the xenon-13l(stable) ground state by gamma emission. Themost prominent beta (85% branching ratio)has Emax = 606 keY, followed by a 364 keYgamma. This gamma is the emission which isprincipally used for detection. About 15%of the decays proceed by a weaker S- (Emax =315 keY) followed by a more energetic gamma(638 keY).

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Burnett's calculation or about 0.001 pCi/m3

using VanAs and Vleggaar's measurements foriodine washed out of the air by rain. Thislatter figure (0.001 pCi/m3) is precisely afactor of 100,000 less than the original MPCaof 100 pCi/m3 • The calculation just performedtherefore seems to be the approximate reasoning behind the ABC's proposed reduction factor(Ref. 4).

3. SOURCES OF ENVIRONMENTAL RADIOIODINE

Both 131 1 and 1291 are important fissionproducts in the nuclear reactor industry:the fission yields (iodine atoms per fission)from uranium-235 in power reactors are 2.9%for 1311 (Ref. 8) and 1.0% for 1291 (Ref. 9).Because of its long half-life, there will bea long-term buildup of 1291 as the nuclearpower industry grows. One projection, fromOak Ridge National Laboratory (Ref. 8), indicates that the total annual U.S. generation of 1291 in the years 1970, 1980, 1990,and 2000 will be 2, 110, 440, and 670 curies/year, respectively. On this time scale essentially none of the 1291 decays, and the'total accumulated activities up to thosefour years will be 2, 480, 2700, and 7600curies, respectively. A good discussion of1291 and its role in the nuclear power industry can be found in the article by Russelland Hahn (Ref. 9).

With its eight-day half-life, there isno long-term bUildu~ of iodine-131. Of course,the inventory of 13 I will grow as the nuclearpower industry grows. The routine releasesof 131 I from operating nuclear power plantsare small, but 131 1 could be a serious problemnear fuel-reprocessing plants, especiallywhen future breeder-reactor fuel is being reprocessed • • • this is discussed in the section on "Fuel Reprocessing Plants" elsewherein this Volume. The requirement of ISO-dayhold-up of spent fuel before present reprocessing is §overned mainly by the need toeliminate 1 1I by decay. Under present normalo~erating procedure, essentially no 1291 or1 11 is released to the environment from thenuclear reactor itself. At the reprocessingplant a very large fraction of the total inventory is released into the stack and mustbe removed to prevent its release to the environment. Fortunately, the need for iodineremoval (mainly because of 131 1) was recognized early; this has brought about the introduction of scrubbing techniques, filters, andother methods, so that today ~ 1/2% of thefuel inventory is actually released (Ref. 8).

Fallout is another source of radioiodine.During the large scale atmospheric bomb testsof the early 1960's (and to a lesser extentduring recent French and Chinese atmospherictests), iodine-13l was present in fallout

throughout the northern hemisphere. Itsprincipal route to humans is through thegrass-cow-milk sequence, on which considerable research has been conducted.

There are thus three main potentiaZsources for fission-product iodine-129 andiodine-13l release to the environment:

(a) fallout from nuclear bomb tests in theatmosphere;

(b) release from the normal operations ofnuclear power reactors;

(c) release from nuclear fuel-reprocessingplants.

Other sources of lesser importance, butnevertheless requiring measurement capability,are from fuel transportation accidents, fromleakage out of storage facilities, and frommedical and industrial uses.

The media which require measurement arevaried: biological samples (urine, feces);whole-body or external (thyroid) counting;food, principally milk; soil samples; air

-filters; and water effluent streams. Tofurther complicate the measurement problem,the radioiodines can occur in any of severalchemical forms: as elemental iodine, protein-bound iodine, ionic iodates and iodides,or various simple organic compounds such asmethyl iodides.

The measurement of radioiodines inbioassay samples (whole body; urine; feces)will not be discussed here; the reader isreferred to Volume 4 ("Biomedical") in thisSurvey.

Radioiodines are now in widespread usein nuclear medicine: for example, about750,000 individuals received iodine-13l forthyroid uptake or thyroid function in 1966,with an average activity of 35 microcuriesper application (Ref. 10). This adds up toabout 30 curies of 131 1 nationwide, andalthough some of it decays in the body asizable fraction (~ 50%) is expelled as humanwaste into municipal wastewater systems.

The recent development of diagnosticprocedures using a different isotope, iodine123, has enabled the individual dose perapplication to be reduced considerably: theaverage iodine-123 thyroid dose is only 1 to3% of the dose from a similar procedureusing iodine-13l (Ref. 11). The probablespread of iodine-123 usage will requiremeasurements of its specific activity invarious media (e.g., urine, wastewater).Iodine-123 has a 13.3 hour half-life, andits principal emission is a l59-keV gamma.It is thus probable that iodine-123 can be

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measured in environmental media with sufficientsensitivity by gamma spectroscopy.

A discussion of the present and potentialuses of several of the radioiodine isotopescan be found in an article by Wellman andAnger (Ref. 12).

There is a considerable range in thespecific activity levels which require measurement, depending upon the mediwn sampled.For example, in a study of the Nuclear FuelServices (NFS) reprocessing plant (Ref. 13),the activity released during reprocessing ofone metric ton of fuel (20,000 megawatt daysburnup, aged 150 days) was about 1.8 curiesof iodine-13l and 0.022 curies of iodine-129. Normal use of a silver-reacting scrubberreduces these activities by a factor of 200before release to the stack, so that thereleased activities should be 9 and 0.11milliauries, respectively. Since levels suchas this are liberated daily at the (design)rate of 1 ton of fuel per day, it can beseen that activities in the millicurie rangewould require measurement; this turns out tocorrespond to specific activities of a fewx 10- 3 pCijaubia meter of staak gas. forboth iodine-13l and iodine-129.

1957: about sixty stations throughout theU.S. collect samples which are analyzed bythe P.H.S. for iodine-13l, cesiwn-137, barium140, strontium-89, and strontium-90 (Ref. 15).

The use of low-background gamma spectrometer systems is discussed elsewhere in thisVolume (see "Gamma Spectrometry") and willnot be treated in detail here. The twodominant types of instruments are sodiwn-iodidecrystal spectrometers and lithium-driftedgermarium semiconductor spectrometers. Thekey to achieving great sensitivity for 131 1measurements is the preparation of samples forthe gamma-spectrometry measurements. Thisusually consists of chemical concentrationprocedures, which we shall discuss for eachof the various media in the next paragraphs.

The minirnwn detectable concentration(MDC) of 131 1 using gamma spectroscopy variesconsiderably. For example, we shall quotebelow (from the Intersociety Committee,Ref. 16) an MDC of about 10 pCi; and we willindicate that an MDC of about 1 pCi is verynearly as well as can be done using very-lowbackground gamma systems and a 1000-minutecounting period.

3/4" MUltiplierPhotot ube

BetaSignal

Lower'-----"-__ Gam ma

Signal

Nal(T\)Crystal

Na I (T\)ICrystall

Upper,..----r---Gamma

Signal

Using specially designed systems whichdetect beta-gamma coincidences, lower MOCvalues have been achieved. As an example,Brauer et a1. (Ref. 36) have used a 5" x 5"NaI(TI) well-type spectrometer, inside ofwhich is placed a 0.75" x 0.020" plasticscintillator. Betas detected in the plasticphosphor ar~ recorded in time coincidencewith gammas detected in the NaI(Tl) wellcrystal; this arrangement lowers backgroundsconsiderably. Figure 1 shows the set-u~schematically; a typical spectrum for 1 11

is shown in Figure 2. Brauer et al. quote aremarkably small MOC of about 0.01 pCi usingthis system (Ref. 36).

FIGURE 1. Low-level beta-gamma detector.showing beta phosphor inside welltype NaI(Tl) system (from Ref. 36).

4. MEASUREMENT CONSIDERATIONS: IODINE-13l

In deer thyroids taken near the NFSreprocessing plant, iodine-129 concentrationsin the range of a to 210 pCi/gram have beenobserved (Ref. 9). A study of bovine thyroidsrevealed iodine-13l concentrations in therange up to about 100 pCi/gram, observedshortly after the detonation of nuclear weapons by the Chinese in 1965 (Ref. 14). Concentrations at other times were at least anorder of magnitude smaller.

Iodine-13l concentrations are typicallybelow one pCi/liter in milk samples routinelymeasured by the U.S. Public Health ServicePasteurized Milk Network (Ref. 15). Thisis also the level at which it is necessaryto measure iodine-13l in drinking water orother (liquids in) foodstuffs.

The measurement of iodine-13l in environmental media is nearly always performed bydetecting its 364-keV gamma (85% branchingratio); sometimes also by its 638-keV gamma(15%); and less often by its betas. Becauseof its relatively high toxicity (reconcentration in the thyroid), the MPC levels forit are low. Methods for assessing iodine-131concentrations in milk have received considerable attention, because the early fallout data seemed to indicate. that this was theprincipal pathway for iodine-13l exposure toman. The U. S. Public Health Service hasmaintained its Pasteurized Milk Network since

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"Although collection of elementaliodine vapor on charcoal under thedescribed conditions will approximate100%, other vaporous iodine compoundssuch as organic iodides or hydrogerliodide may have much lower efficiencies."

"The minimum detectable quantity(10 pCi of iodine-131) can be determined with a precision of 10% atthe 95% confidence level by employment of a well-shielded countingsystem and a sufficiently longcounting time. • • ."

The "Tentative Method" relies on an accurate flow measurement of sampled air throughthe system. The recommended charcoal cartridges are 5/8" in diameter and 1-1/2" deep,containing 3 grams of 12-30 mesh activatedcharcoal. After collection, the sample iscounted in a NaI(T1) scintillation countingwell-type detector coupled to a mu1tichaIlne1analyzer. In the presence of other gammaemitters, decay measurements of the iodine-131photopeak can be made over several days toobserve the 8-day half-life. Calibration isby the use of a standard iodine-131 sourcein the same geometry as the unknown sample.

One of the difficulties with this 'standard method' is that it employs a NaI(Tl)scintillation detector. In the presence ofother (higher-energy gamma) emitters a substantial interference can occur, making quantitative measurement difficult due to backgrounds under the iodine-131 peak. The useof a semiconductor-detector/spectrometerwould improve this because of its vastlysuperior resolution.

A specially-prepared filter for collection of iodine has been described by Barattaet a1. (Ref. 17). The filter is impregnatedwith barium hydroxide-iodide-iodate, andafter sample collection the iodine is concentrated chemically by dissolution andexchange between the radioiodine and thestable iodine.

In the presence of extremely largegamma background, the Intersociety Committee(Ref. 16) indicates that it is necessary toemploy chemical-separation techniques beforecounting.

Concentrations as low as 10- 14 jJCi/cm3(0.01 pCi/m3 of air) can probably be measured,using the ultimate in state-of-the-art techniques. For example, using the sampling rateof 0.01 m3/minute mentioned by the Intersociety Committee, a week's run will sampleabout 100 m3 of air and collect 1 pCi of131I (at a concentration of 0.01 pCi/m3).This is just about the minimum detectableactivity which one can expect to measure in

Gamma spectra of separated iodinesample taken in a 5" x 5" NaI(Tl)well system. with beta detectionwith small plastic phosphor insidewell (see Figure 1). Gamma andbeta-gamma coincidence spectrashown separately (from Ref. 36).

106r=---------------,

A. 131I in Air

"The proposed method involves samplingiodine in its solid and gaseous stateswith an 'absolute' particulate filterin series with an activated charcoalcartridge. The iodine-131 activity isthen quantitatively determined bygamma spectroscopy. Iodine adsorbedon solid particles and possibly somevaporous iodine will be deposited onthe 'absolute' filter while the remaining vaporous iodine will be ad-sorbed on the activated charcoal. "

1010'----'---0"-.'---'----'-0.8---'

GAMMA ENERGY· MeV

'Minimum detectable quantity ofiodine-131 by gamma spectroscopy isapproximately 10 pCL At a samplingratio of 0.01 m3/min the practicalminimum detectable quantity for a7 day sample is 0.1 pCi/m3 (1.0 x 10- 13JJCi/cc). . . ."

The task of measuring iodine-131 activityin the atmosphere is complicated by the multiplicity of possible chemical forms, such asgaseous I2, organic gaseous iodides and iodates,vapors adsorbed on particulate matter, andparticulate iodine compounds. Recently, theIntersociety Committee published a "TentativeMethod for Analysis for Iodine-131 Content ofthe Atmosphere" (Ref. 16), and we shall discuss this technique as an example of a numberof similar air-sampling methods. The followingis taken from Ref. 16:

FIGURE 2.

~..

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a very-low-background gamma-spectroscopysystem, even counting for a 1000-minuteperiod (see "Gamma Spectrometry" elsewhere inthis Volume). Increasing the sampling rateby a factor of, say, 3 would yield 3 pCi of131 1 or alternatively reduce the minimumdetectable air concentration by the samefactor of 3. However, too high a samplingrate reduces the collection efficiency of thecharcoal filters, especially for the nonelemental forms of iodine.

B. 13 I I in Milk

The Public Health Service PasteurizedMilk Network has developed a routine, standard analysis procedure for iodine-13l determinations in milk (Ref. 18, 19). After acomposite is made from each sampling stationin the network, the following simple procedureis carried out: with a gamma-ray scintiZZation spectrometer used for a 50-minute countingtime, the three major gamma-emitters commonlyfound in milk (iodine-l3l, cesium-137, andbarium-140) are all determined with minimumdetectable concentrations in the range of10 pCi/liter. A description of the gammaspectroscopy technique with NaI(Tl) scintillator, as developed by the PHS, can be foundin the article by Hagee, Karches, and Goldin(Ref. 20).

Methods for iodine-13l in milk withoutthe use of gamma spectroscopy must, of course,rely on chemical separation techniques toisolate individual radionuclides. Variousseparation techniques have been developed,mostly using an anion exchange resin followedby gamma counting. This method relies upontwo facts: that "iodine-13l in market milkis mostly in the inorganic form as the iodide,very little being bound by proteins" (Ref. 19);and that "of the several fission products . • . ,iodine-13l is the only anionic radionuclidepresent in milk" (Ref. 20).

The method described by Murthy (Ref. 19)is typical: 50 ml of anionic resin (stronglybasic quaternary type, 20-50 mesh size, inchloride form) with 1 gallon of milk flowingthrough the column at 40-50 ml/min will recover all but the protein-bound iodine.Single-channel counting with a 2" NaI(Tl)crystal is used, and concentrations in therange of 50 pCi/liter can be determined to±4 pCi/liter.

In another similar method described byPorter and Carter (Ref. 21), the anion exchange resin retains 96 ± 2 percent of theradioiodine in the first liter of milk, witha loss of an additional 2% per liter up tofour liters. Porter and Carter's method isdesigned for sample collection in the field,at a very low (1965) cost of about $3 for thecomplete field sampling. unit, plus $0.50 per

(non-reusable) vial with resin. The analyticaland counting work is subsequently performedin the laboratory.

Both of the above methods are termed"rapid", meaning that determinations may bemade in 2-3 hours.

Another method for fresh whole milksamples is described in the U.S.A.E.C. Healthand Safety Laboratory's Manual (Ref. 22):

"Iodine-13l in whole milk samplesis collected by the coagulation ofprotein-bound iodine with trichloroacetic acid and the simultaneousprecipitation of ionic iodine assilver iodide. The filtrate fromthis separation and an aliquot ofthe untreated milk are then gammacounted on a NaI(Tl) scintillationcrystal assembly."

This procedure has the advantage of measuringany protein-bound iodine-l3l. However, thesubtraction of the corrected counting ratewith and without treatment is necessary. Ofcourse (quoting from Ref. 22 again), "theanalysis may be made more specific by measuring with a gamma spectrometer."

Concentrations as low as fractions ofone pCi/liter of milk can be measured if thechemical analysis procedure can remove enoughiodine from enough milk. For example, using10 liters of milk at 0.1 pCi/liter, one can bybrute force obtain 1 pCi of 131 1 for determination by gamma spectroscopy. This 1 pCiof activity is very close to the ultimatedetection limits of the better low-backgroundgamma-spectroscopy systems, counting for 1000minutes. Alternatively, one can use a commercially-available low-background betacounter of the type designed for tritium.Any of these low-level analyses, if performedcommercially, will cost on the order of $75to $150 per sample (Ref. 23).

It should be noted here that methods havebeen developed for removing iodine-13l fromcontaminated milk samples. It is beyond thescope of this work to discuss them; thereader is referred to a recent EnvironmentalProtection Agency summary (Ref. 24) fordetails.

C. I 3 I I in Water

Two types of waters are of most concern:drinking water and waste water. Measurementsof iodine-13l in drinking water are not maderoutinely as a part of public health practice,and no Standard Method is found in the AmericanPublic Health Association compilation (Ref. 25).The U.S. Public Health Service "Drinking WaterStandards" pointed out in 1962 that "iodine-13lis not found in significant quantities in

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public water supplies frequently enough tocall for routine monitoring" (Ref. 26). Thereason for this is that fallout iodine-13ldoes not significantly contaminate surfacewaters because of dilution, nor ground watersbecause of both dilution and the 8-day halflife; furthermore, in the event of massivefallout reconcentration in the grass-cow-milksystem would produce significant iodine-13lcontamination in milk of far greater consequence than for drinking water.

Contamination of waste waters is ofgreat concern, however, because of increasinguse of the radioiodines in the medical andindustrial fields. The American Society forTesting and Materials (Ref. 27) has publishedthree different Standard Methods for radioiodines in waste water. The methods are alldesigned for concentrations greater than100 pCi/liter.

The first ASTM method (Ref. 28) employs"cation exchange followed by heterogenousisotopic exchange of iodide with silver iodide:"Only silver isotopes might interfere, andthese are rarely encountered.

The second ASTM method

" •.• is based on the separation ofiodine from other activities by distillation of elemental iodine intocold carbon tetrachloride. To assurechemical interchange with the iodinecarrier an oxidation-reduction cycleis made. The iodine is oxidized toiodate with permanganate, reduced toiodide with bisulfite, and distilledover as free iodine in the presenceof nitrite."

The third ASTM method (Ref. 22)

" .•• is based on the separation ofiodine isotopes from other radioisotopesby extraction into carbon tetrachloride. . • The iodine is oxidized to periodatein the presence of sodium hypochloriteand then reduced to iodide with sodiumbisulfite in acid medium."

In each ASTM method, silver iodide(precipitate) is counted either with a GeigerMUller or proportional counter, or preferablywith a gamma spectrometer of the Na1(Tl) orGe(Li) type.

D. 131 1 in Other Media

The measurement of iodine-13l in mediaother than air, milk, and water is usuallycarried out by routine gamma spectroscopicanalysis. For that reason, and also becausevery little in the way of concern has arisento motivate specialized techniques in othermedia, we shall not discuss the measurements

here. The reader is referred to the section"Gamma Spectrometry" elsewhere in this Volume.

Measurements in bioassay media (urine,whole body, etc.) are discussed in Volume 4("Biomedical") of this Survey.

E. Quality Control

Quality control is one of the most important steps in the entire measurement process.

The calibration of gamma spectroscopic systemshas been discussed in "Gamma Spectrometry"elsewhere in this Volume and will not be treatedhere. The other key part of the iodine measurement system is the chemical-separation process.

Unfortunately, quality-control checkshave usually revealed significant variationsamong laboratories analyzing for 131 1 at lowlevels. These variations are a cause forconcern since they demonstrate the fundamentaldiffiCUlty in making routine, reliable, accurate 1311 measurements in environmentalmedia.

We shall discuss one recent study as anexample•••• others show comparable results.In 1971, the EPA Office of Radiation Programscarried out a study of analysis capabilitiesin milk (Ref. 30). 35 participating laboratories made triplicate determinations ofunknown concentrations of 131 1, 89Sr, 90Sr ,and 137CS at activity levels (± 2%) of 69,31, 42 and 52 pCi/liter, respectively. Unfortunately, six laboratories reported resultswhose mean exceeded the 'control level' ofabout ±15% for 1311. [For 89Sr , 9°Sr, and137CS the outlying laboratories numbered 4,9, and 2, respectively.] For many of theoutlying laboratories in the 131 1 study, therange of reported results for the triplicateanalyses exceeded 30%. This study seems toshow that, while many laboratories can perform 131 1 analyses well, a significant minoritycannot.

5. MEASUREMENT CONSIDERATIONS: IODINE-129

1odine-129 decays with a l7-million-yearhalf-life by emitting a low-energy beta(Emax = 150 keV) followed by a 40-keV gamma.Both the beta and gamma are of relatively lowenergy, and consequently difficult to detect.The MPC values for 1291 are all about a factorof 5 more restrictive than those for 131 1(because after ingestion or inhalation the131 1 decays relatively rapidly with its 8-dayphysical half-life while the 1291 lasts forthe biological half-life of about 180 days).Combining these considerations, the measurement problem is seen to be fairly difficult.

Fortunately, however, the long half-lifeand low specific activity can be used to

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advantage. Since 1 curie of 1291 weighsabout 6000 grams, even minute activitiesrepresent sizeable numbers of atoms amenableto techniques besides direct radioactivecounting.

We shall discuss two measurement techniques: liquid scintillation counting andneutron activation analysis. The former isuseful when the activity to be measured isknown to exceed a few pCi of 1291, while thelatter is recommended for the ultimate insensitivity. In either case, the iodine mustbe isolated chemically to free it from thesample matrix in which it is found. We shallnot discuss here any of the several radiochemical techniques already mentioned foriodine-13l.

A. Liquid Scintillation Counting

This method relies upon the ability ofa liquid scintillation system to detect thelow-energy beta particles from 1291. As justmentioned, the iodine must be isolated chemically before introduction to the scintillationsystem, to provide a small sample free of themany impurities which might cause quenching(self-absorption by the sample of the scintillation light).

Liquid scintillation counting has beendiscussed in depth in the section "Tritium"elsewhere in this Volume, and that discussionwill not be repeated here. The best systemshave minimum detectable activities (30) fortritium in the range of about 1 RCi/cm3 ofwater, and the performance for 1 91 should becomparable. In the liquid scintillation methoddescribed by Magno et al. (Ref. 31) andGabay et al. (Ref. 32), the only feature whichis different for 1291 than for tritium is thatthe sample is placed under a fluorescent lightfor about 2 hours to decolorize the iodinebefore counting. A possible source of erroris that the counting efficiency for 1291must be known as a function of energy, sincethe wide beta energy spectrum extends fromthe maximum (ISO keV) down to zero energy. Astandard 1291 solution is useful for this purpose. The U.S. National Bureau of Standardshas recently prepared such a standard(Ref. 33). The calibration shOUld, if possible,be performed experimentally rather thendetermined by calculation. since the 1291beta is followed essentially immediately bya 40-keV gamma ray which will also be detected in the scintillator some of the time,distorting the apparent beta~energy spectrum.

Using a solvent extraction procedure on4 liters of milk, followed by liquid scintillation counting, Gabay et al. (Ref. 32) reporta 1291 detection limit (95% confidence) ofabout 0.3 pCi/liter, counting for 100 minutesat average background of 25 cpm.

B. Neutron Activation Analysis

lodine-129 determination by neutron activation analrsis relies upon the transformationof 1291 to 3°1 by a neutron-capture reaction:

129 1(n, y) 13 °I 13-, 13 0Xe12.4 hr

The 13°1 is counted in a gamma s~ectrometer by measuring its own decay to 1 °Xe(12.4 hour half-life; one of several betas isfollowed in each case by a series of gammarays, including two easily measurable ones at538 and 669 keV). Typically, 1291 is accompanied in any medium by much larger concentrations of stable, naturally-occurring 1271.This also is determined by a similar (n,y)process:

The 1281 decays to 128Xe with a 25-minutehalf-life; the most easily detected emissionis a 44l-keV gamma ray (13%).

The intrinsic limit on sensitivity ofthis method is caused b{' ~roblems from themultiple activation of 2 I up to 13°1, whereit masks 1291:

Typically, neutron activation analysisis capable of measuring 1291/1271 ratios tomuch greater precision than the determinationof the 129 1 activity itself. This ratio maythen be used together with other informationon 1271 content to determine 1291 very well.

Neutron activation analysis for_ 1291 wasfirst suggested by Edwards (Ref. 34), whopointed out the possible use of 1291 asan environmental tracer. More recent investigations by Keisch et al. (Ref. 35), Cochran(Ref. 13), and Magno et al. (Ref. 31) showthat with chemical separation the techniquesuffers few interferences and may be useddown to very low concentrations. As mentionedabove, iodine-isolation chemistry is requiredto obtain the ultimate in sensitivity; forexample, an important interference can resultif stable cesium-133 is present, since thereaction 133Cs(n,a)1301 produces the same13°1 isotope as that from (n,y) activation of1291.

Because of the multiple-capture production of 13°1 from 1271, there is an optimumneutron flux for the ultimate sensitivity.Keisch et al.(Ref. 35) have shown this to beabout 1013 thermal neutrons cm- 2sec- 1• Theseinvestigators report that the theoreticallimitation on the 1291/1271 ratio would beabout 3 x 10- 13 in a sample containing one

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gram of iodine. This corresponds to an incredibly small 1291 activity of about 5 x 10- 17 Ci!

Ordinary gamma-spectrometry measurementsafter activation are performed using NaI(Tl)or Ge(Li) systems. Keisch et al. (Ref. 35)also report use of a beta-gamma coincidencearrangement for. 13°1 to reduce backgrounds.This in turn may suffer interferences in thepresence of the isotope 1261, which is also abeta-gamma coincidence emitter. 1261 is produced from 1271 by the reaction

This occurs when the beam contains neutrons ofhigher than thermal energy. Use of a wellthermalized neutron flux suppresses this backgrolli1d.

Boulos et al. (Ref. 36) report a variationon activation analysis, in which after irradiation the sample is measured in a mass-spectrometry system for the xenon isotopes which arethe end-products of 13°1 and 1281 decay. Boththe 130Xej128Xe and the 130Xe/126Xe ratiosshould be indicative of the 1291/1271 ratio.Detection limits on the ratio in the range of~10-10 are reported.

as organic iodides or hydrogen iodide arepresent since they are not efficiently collected. Clearly, some improvement is needed here,since precise measurement on part of a potential problem is not adequate when one cannotbe sure that other parts are also well belowlevels of concern.

c. Iodine-1Jl in other media. Gammaspectroscopy appears to be generally adequatefor activity determinations in most solid media,such as biological samples.

d. Iodine-129. The problem of samplingiodine-129 in air is similar to that for iodine-131 (see above). However, iodine-129 isnot now often a problem of human radiologicalsignificance (even locally near nuclear fuelreprocessing plants), and measurements of itare principally to assure that it is not released to the environment in the first place.The restrictions on release, in turn, are toprevent long-term environmental build-up.Both neutron activation analysis and liquidscintillation spectrometry appear adequate todetermine 1291 in the media requiring measurement.

6. SUMMARY AND CONCLUSIONS CONCLUSIONS

The intent of this section has been todiscuss the sources and principal measurementtechniques for radioiodine (iodine-13l andiodine-129) in the environment. Here we shallsummarize the present situation by delineatingthe various individual measurement problems:

a. Iodine-1Jl in miZk. Milk is themedium to which the greatest effort has beendevoted. There are several rapid laboratorymethods for milk analysis at minimum detectable concentrations of about 10 pCi/liter, andwith the very best equipment and long countingperiods fractions of 1 pCi/liter can be de- .termined. Field sampling methods for milk arewell in hand, but laboratory analysis is stillrequired and 2-3 hour determinations are considered "rapid". It appears that instrumentation is now adequate to cover this measurementproblem.

b. Iodine-1Jl in air. The "TentativeMetho~' of the Intersociety Committee can determine levels in the region of 0.1 pCi/m3;the MPC level for the general public is 10pCi/m3. However, this is for a seven-daysample; for a one day sample the minimumdetectable level would be seven times higher.

Detection limits perhaps one order-of-magnitude lower can be obtained using the very bestlow-background equipment. This method is notadequate when vaporous iodine compounds such

Measurements of iodine-13l in air, milk,and solid biological samples can (in the opinionof the authors) all be made with existinginstrumentation to sufficient accuracy and lowenough concentration. The only exception isfor those vaporous iodine compolli1ds such aslight organic iodides or HI which are notpresently collected with adequate efficiencyin the established method for determiningiodine-13l in air. For iodine-129 the situation is also reasonably well developed.

7. ACKNOWLEDGMENT

For this section we gratefully acknowledge thegenerous advice and review of:

Edmond J. Baratta~

Northeastern Radiological Health Laboratory

Leon Leventhal,LFE Environmental

John M. Matuszek,New York State Department of Health

George A. Morton,Lawrence Berkeley Laboratory

Douglas P. Serpa,Pacific Gas and Electric Company

'.)

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8. REFERENCES


1. International Commission on Radiological Protection, Report ICRP No.2, Pergamon Press,Oxford (1959).

2. H. Cember, Introduction to Health Physics, Pergamon Press, Oxford and New York (1969).

3. 10CFR20 (Code of Federal Regulations, Title 10, Part 20), "Standards for Protection AgainstRadiation," Appendix B, Table II, Concentrations in Air and Water Above Natural Background.

4. U.S. Atomic Energy Commission, "Licensing of Production and Utilization Facilities: LightWater-Cooled Nuclear Power Reactors," Federal Register 36, no. 111, pp. 11113 (9 June 1971).

5. T.J. Burnett, "A Derivation of the "Factor of 700' for Iodine-13l," Health Physics 18, 73(1970). -

6. D. VanAs and C.M. Vleggaar, "Determination of an Acceptable Iodine-13l Concentration in AirWhen the Critical Intake Is Through Milk," Health Physics 21, 114 (1971).

7. F. Morley and P.M. Bryant, "Basic and Derived Radiological Protection Standards for theEvaluation of Environmental Contamination," in Environmental Contamination by RadioactiveMaterials, International Atomic Energy Agency, Vienna (1969).

8. "Siting of Fuel Reprocessing and Waste Management Facilities," Report ORNL-445l, Oak RidgeNational Laboratory, Oak Ridge, TN 37830 (1971).

9. J.1. Russell and P.B. Hahn, "Public Health Aspects of Iodine-129 from the Nuclear PowerIndustry," Radiological Health Data and Reports, g, 189 (April 1971).

10. A.W. Klement, C.R. Miller, R.P. Minx, and B. Shleien, "Estimates of Ionizing Radiation Dosesin the United States, 1960 to 2000," Report ORP/CSD 72-1, U.S. Environmental Protection Agency,Office of Radiation Programs, Rockville, MD 20852 (1972).

11. B.M. Branson, H.N. Wellman, and J.G. Kereiakas, "An Ultra-Sensitive Iodine-123 Thyroid UptakeSystem Utilizing Peak: Scatter Organ Depth Correction," Int. J. Appl. Radiat. Isotopes 22,502 (1971). -

12. H.N. Wellman and R.T. Anger, Jr., "Radioiodine Dosimetry and the Use of Radioiodines Otherthan Iodine-13l in Thyroid Diagnosis," Seminars in Nuclear Medicine, International AtomicEnergy Agency, Vienna (1971).

13. J .A. Cochran, et al., "An Investigation of Airborne Radioactive Effluent from an OperatingNuclear Fuel Reprocessing Plant," Report No. BRH/NERHL 70-3, Northeastern Radiological HealthLaboratory (now part of E.P.A.), Winchester, MA 01890 (1970).

14. E.J. Baratta, "Uptake of Iodine-13l in Bovine Thyroids,'" p. 609 in Radioecological Concentration Processes, proceedings of a symposium in Stockholm, 25-29 April, 1966. PergamonPress, Oxford (1966).

15. The U.S. Public Health Service Pasteurized Milk Network reports its radionuclide measurementsperiodically in Radiation Data and Reborts. Nuclides analyzed are strontium-89 and 90,iodine-13l, cesium-137, and barium-14. The most recent extensive discussion of its procedures is in vol. ~, pp. 731 ff. (December, 1968).

16. Methods of Air Sa~ling and Analysis, Intersociety Committee for a Manual of Methods forAmbient Air Sampllng and Analysis. American Public Health Association, 1015 - 18th Street,N.W., Washington, DC 20036 (1972).

17. E.J. Baratta, G.E. Chabot, and R.J. Donlen, "Collection and Determination of Iodine-13l inthe Air," Amer. Ind. Hygiene Assn. J. 29, 159 (1968).

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18. B. Kalm, G.K. Murthy, C. Porter, G.R. Hagee, G.J. Karches, and A.S. Goldin, "Rapid Methodsfor Estimating Fission Product Concentrations in Milk," Environmental Health Series, U.S.Dept. of HEW, Public Health Service, Publication PHS-999-R-2 (1963).

19. G.K. Murthy, "Rapid Detennination of Iodine-13l in Milk," p. 7 of Ref. 18.

20. G.R. Hagee, G.J. Karches, and A.S. Goldin, "Detennination of Iodine-13l, Cesium-137, andBarium-140 in Milk by Garruna Spectroscopy," p. 17 of Ref. 18.

21. C.R. Porter and M.W. Carter, "Field Methods for Rapid Collection of Iodine-13l from Milk,"Public Health Reports 80, 453 (1965).

22. J •H. Harley (ed.), HASL Procedures Manual, Report HASL- 300, USAEC Health and Safety Laboratory,376 Hudson Street, New York, NY 10014 (1972). Earlier editions of this manual were publishedas Report NYO-4700.

23. Teledyne Associates, Westwood, NJ (March 1973).

24. D.G. Easterly, LB. Brooks, J.K. Hasuike, and C.L. Weaver, "Development of Ion ExchangeProcesses for the Removal of Radionuclides from Milk," Report RO!EERL 71-1 (1971). EPAEastern Environmental Radiation Laboratory, Box 61, Montgomery, AL 37101.

25. Standard Methods for the Examination of Water and Wastewater, 13th Edition, American PublicHealth Association, 1015 - 18th Street, N.W., Washington, DC 20036 (1971).

26. "Public Health Service Drinking Water Standards, Revised 1962," P.H.S. Publication No. 956,U.S.P.H.S., Washington, DC 20525 (1962).

27. Annual Book of ASTM Standards, Part 23 (1971), American Society for Testing and Materials,1916 Race Street, Philadelphia, PA 19103. The radioiodine methods are designated D2334-69.

28. The first ASTM method is based on W.J. Maeck and J.E. Rein, "Detennination of Fission ProductIodine, Cation Exchange Purification and Heterogeneous Isotopic Exchange," Anal. Chern. 32,1079 (1960). -

29. The third ASTM method is based on L.E. Glendenin and R.P. Metcalf, National Nuclear EnergySeries, Vol. 9, Book 3, p. 1625; and G.J. Hunter and M. Perkins, "The Detennination ofRadioiodine," Report AERE-AM 64 (1960), Atomic Energy Research Establishment, Harwell, U.K.

30. F. Knowles, "Interlaboratory study of 131 1, 137CS, 89Sr, and 90Sr Measurements in Milk,"Teclmical Experiment 7l-MKAQ-l, EPA Office of Radiation Programs, 109 Holton Street,Winchester, MA 01890 (1971).

31. P.J. Magno, T.C. Reavey, and J.C. Apidianakis, "Iodine-129 in the Environment Around a NuclearFuel Reprocessing Plant," unpublished report U.S. Environmental Protection Agency, Office ofRadiation Programs, Washington, DC 20460 (1972).

32. J.J. Gabay, C.J. Paperiello, S. Goodyear, J.C. Daly, and J.M. Matuszek, "A Method forDetennining Iodine-129 in Milk and Water," submitted to Health Physics (1973). N.Y. StateDept. of Health, Albany, NY 12206.

33. Office of Standard Reference Materials, U.S. National Bureau of Standards, Washington, DC20234. The iodine-129 standard, designated SRM4949, contains about 0.2 ~Ci!gram of solution with ±1.7% uncertainty.

34. R.R. Edwards, "Iodine-129: Its Occurance in Nature and Its Utility as a Tracer," Science137, 851 (1962).

35. B. Keisch, R.C. Koch, and A.S. Levine, "Detennination of Biospheric Levels of Iodine-129 byNeutron Activation Analysis," p. 284 in Modern Trends in Activation Analysis, ActivationAnalysis Research Laboratory, Texas A and MUniversity, College Station, TX 77843 (1965).

36. F.P. Brauer, J.H. Kaye, and R.E. Connally, "X-Ray and Beta-Garruna Coincidence SpectrometryApplied to Radiochemical Analysis of Environmental Samples," in Advances in Chemistry Series,no. 93, p. 231 (1970).

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RADON-222 AND ITS DAUGHTERS

1. Introduction

2. Physical Considerations

a. Radon-222 and Its Decay Chain

RAD-NUCRadon-222and DaughtersPage 1 Jan. 1973

b. Radon-220 (Thoron) and Radon-219 (Actinon)


4. Sources of Radon and Its Daughters

5. Measurement Techniques

a. Radon as Gas

b. Working Level

c. Measurements of Individual Radon Daughters in Air

d. Personnel Dosimeters


7. Acknowledgment

8. References

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The properties of the chain radium +

radon-daughters concern us here. Note thatradium-226 has a half-life of 1602 years.Since that is much longer than the half-lifeof any subsequent daughter, 226Ra can beviewed (for short times) essentially as afixed-rate generator for 222Rn (whose halflife is 3.82 days). The equilibrium build-upof the succeeding daughters (RaA, RaE, Rae)is shown in Figure 3 (from Ref. 2). Notethat after RaC decays, RaC" follows nearlyimmediately (164 ~sec) and that RaD (210Pb)has a 22-year half-life, which for short timeseffectively blocks the decay chain. Hence weshall deal here almost exclusively with thefirst four daughters, RaA, RaB, RaC, and RaC".

Evans (Ref. 2) has given a very usefulsummary of the physical and engineering considerations concerning the radon daughters.The chemical properties of the daughters arecrucial. Although radon in inert, the threeelements immediately below it in the periodictable (polonium, bismuth, and lead) are allchemically active. In particular, when .radon(gas) decays, most of the newly created 218pO(RaA) atoms, typically ionized, tend to attachalmost immediately to any particulate matterin the atmosphere. Most RaE, RaC, and RaC"atoms are so attached at birth. In dust-ladenmine air, the consequence is that the particulate matter becomes radioactive by adsorption.Whether or not they are attached to particulatematter, the daughters cause important radiological consequences when inhaled, since theytend to lodge in the lung mucosa.

The alpha-emitting daughters are RaA andRaC" • The alpha decay energies are as follows:

1. INTRODUCTION

In the uranium mining industry, radiological exposures to radon-222 daughters are themost significant hazard. Radon gas also appearsin the natural radiation environment wherevernatural uranium exists in surface rocks andores. Because of their importance, and becauseinstrumentation for their measurement isunique, radon and its daughters are discussedhere in a separate section of this Survey.

We shall begin by outlining the physicalcharacteristics of the radon decay chain, andfollow with discussions of the radiation protection guides and the special unit (WorkingLevel) developed for measuring these activities.Finally, we will discuss the types of measurement capabilities required of instrumentation,and the instrumentation itself. We shall dealboth with measurements in the natural environment, and also with measurements for occupationalradiation exposure monitoring and control,mainly in uranium mines.

2. PHYSICAL CONSIDERATIONS

a. Radon-222 and Its Decay Chain

The decay chain of which radon-222 is apart is one of the oldest and best-studiedphenomena in nuclear physics. It begins withthe naturally occurring isotope uranium-238and ends with the stable lead-206. In betweenthere are 8 alpha decays and 6 beta decays.The first part of the series (uranium-238 toradon-222) is shown in Figure 1, while Figure2 shows the second part (radon-222 to lead206). More detailed data are given in Table1 (from Ref. 1). Note that many of the chainmembers are still often referred to by theirhistorical names, and we shall often use thisnomenclature here also.

222Rn

218pO(RaA)

21 '+Po (RaC")

+ 218pO (RaA)

+ 21'+Pb(RaE)+ 210pb(RaD)

5.48 MeV6.00 MeV7.69 MeV

\~j

Radon-222 provides a natural division forour purposes, because we are interested mainlyhere in radon and its daughters. However,there is also an important physical basis forthe separation: that is, radon is an inert gas.As 23ltU decays through five steps to 226Ra,the heavy nucleus remains fixed in place (inrock, for example). However, there is diffusionof radon gas from the local site of production,and in any particular (surface) rock some ofthe radon will escape into the surroundingatmosphere. This is the source of the historical name for 222Rn, "Emanation Radon".

Thus for many practical purposes one canthink of uranium-laden ore as a "source" ofradon gas, as well as a "source" of the manylX,S, and y radiations being emitted by theconstituent nuclei themselves.

The energy differences can, of course, providea basis for distinguishing the individualcomponents by alpha spectroscopy.

The two important beta/gamma-emittingdaughters are RaE and RaC. Each has a rathercomplicated set of emissions, with three important betas and several gamma lines each(see Table 1). Because of this, beta detectionas a means of measurement is complicated:the spectral efficiency of any beta detectoris very hard to determine. The RaE and RaCgamma lines could be detected by gamma-spectroscopic methods but this is not now commonlydone.

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Radon-2223.62 days

a (S,49)

n

Uranium - 236(U I)

4.Sx109 years

a (4.IS,4.20)

Thorium -e34(U Xi)

24.1 days

13(0.103,0.193)

ProtactInium - 234(U Z)

6.7S hours

a (4.72,4.77)

Thorlum-230(Ionium)

60,000 years

Polonium -216(Ra A)

3.0S minutes

a(6.00)

a(7.69)

Lead-210(Ra D)

22 years

0.0< ~P(0.33~:---' r------,

I Astatine -2162 seconds

Thallium -210(Ra e")

1.3 minutes

a (4.62,4.66)

Radium-2261602 years

a (4.60,4.76)

Rodon-222

3.62 days

XBL7212-4904

FIGURE 1. Deaay Chain,Uranium-238 to Radon-222

(a, f3 energies in MeV)

13(0.016,0.061)

Blsmuth-210(Ra E)

S.OI days

130.161)

Polonium-210(Ra F)136doys

a(S.31)

Lead-206(Ro G)Stable

XBL7212-4903

FIGURE 2. Deaay Chain,Radon-222 to Lead-206(a, f3 energies in MeV)

f i"' ....

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TABLE 1.


u

Main sequenae of deaays from uranium-238 to lead-206. Three very weak

aollateral branah disintegrations. all with branahing

ratios less than 0.1%. are omitted.(from Ref. 1)

Gannna- AverageBeta rayCOllDllon name Principal Alpha maximum quanta gannna-or symbol Isotope Half life radiations energy energy per ray

(MeV) (MeV) disinte- energygration (MeV)

Uranium I Uranium2 38 4.49 X 10 9 years a. 4.18

Uranium Xl Thorium234 24.1 days 13.205 (80%).H1 (20%)

Protac- 2.32 ~80~}Uranium X2 tinium234 1.17 minutes 13 1.5 (13%)

.6 (7%)

Uranium II Uranium234 248,000 years a. 4.76

Ionium Thorium2 30 80,000 years a. 4.68 (75%)4.61 (25%)

Radium Radium226 1,602 years 4.78 (94.3%)a. 4.69 (5.7%)

Radon Radon222 3.825 days a. 5.486Radium A Po1onium2l8 3.05 minutes a. 5.998

Radium B Lead2l4 26.8 minutes 13 .65y .82 .295

S3.13 (23%)

Radium C Bismuth2l4 19.7 minutes 1.67 (77%)y 1.45 1.050

Radium C' Po1onium2l4 164 llsec a. 7.68

Radium D Lead2lo 22 years 13 .018y 1. .047

Radium E Bismuth2lo 5.02 days 13 1.17Radium F Po1onium2 1 0 138.3 days a. 5.298Radium G Lead206 Stable Stable

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1.1 1""J''"'r-,-.,----r--r--,--.----.

0.7

~

.~ 0.6

:t 0.5

.~~ 0.40:

0.1

40 60 80 100 120 140 160Time in Minutes'

FIGURE 3. Growth of activity of the individuaZshort-Zived decay products in a constant sourceof radon having unit activity (from Ref. 2).

b. Radon-220 (Thoron) and Radon-2l9 (Actinon)

In situations where radon-222 must bemeas~red! two other isotopes of radon are potent1al 1llterferences. The most important isradon-220 (historically known as 'thoron'), amember of the decay chain which originates withnaturally-occurring thorium-232. The otherisotope is radon-2l9 (historically, 'actinon')from the chain orig1llating with uranium-235. 'Both of these gases behave as does radon-222:they emanate from the radioactive ores aftertheir birth by the alpha decays of their immediate parents (224Ra + 22°Rn, 22SRa + 219Rn).

In the uranium mines, thorium content ofthe ores is low (typically < 1% of that of2S8U), and the 2S5Uj2 S8U raho is uniform atabout 0.72%. Thus the equilibrium productionof both thoron and actinon gases is relativelysmall. Equally important, the half-lives arequi~e short (55 sec for thoron, 4.0 sec foract1llon). Because of their limited abundance~d short ha~f-lives, their direct radiologicalunpacts are 1ll both cases much less significantthan that of radon-222.

Some of thoron' s daughters can producepossible backgrounds when radon-222 daughtersare collected on air filters for measurement:212Pb and 212Bi have half-lives of 10.6 and1.01 hours, respectively. Because of actinon'sshort half-life, its ability to diffuse outof earth and rock is so limited that it isseldom, if ever, present at levels requiringmeasurement in the environment.

Throughout this section, the term 'radon'will be used to denote 'radon-222, unlessspecifically stated otherwise.


For the purposes of radiological protectionof the lungs in the uranium mining industrya specialized unit of exposure to radon-222'has been ~eveloped. This is the workinl,Level(WL), def1lled as "any combination of ra n-daughters in one liter of air that will resultin the ultimate emission of 1. 3 x 105 MeV of1?otent~al alpha energy" (Ref. 3). This value1S denved from alpha energies released bythe total decay of the short-lived daughters(~, ~, RaC, ~C~) at radioactive equilibr1um W1th 100 pC1 of 222Rn/liter of air. Notethat the WL considers only the alphas fromradon-222 daughters and not from radon gasitself.

The reason for the specialized unit ismainly operational: the WL is a concepthaving validity in any mixed concentration ofrado~ and ~t~ d~ughters, whether or not theyare 1ll eqmhbnum. Just as important itlends itself to practical measurements'inthe mines.

An extension of the WL concept is the''Working Level Month" (WLM), which expressesa cumulative exposure. It is defined asfollows: "Inhalation of air containing aradon daughter concentration of one WL for170 working hours results in an exposure ofone WLM" (Ref. 3).

The Secretary of Labor, acting underprovisions,of the Walsh Healy Act, promulgatedthe following standard in late 1968 (Ref. 4):

"Occupational exposure to radondaughters in mines shall be controlled so that no individual willreceive an exposure of more that2 WLM in any consecutive 3-monthperiod and no more than 4 WLM inany consecutive l2-month period.Actual exposures shall be kept asfar below these values as practicable."

In early 1969, the Department of theInterior issued the following standard callingfor action on the basis of individual concentrations (Ref. 5):

"If samples show an atmosphericconcentration of radon daughters ofmore than 1 WL but less than 2 WL,immediate corrective action shallbe taken or the men shall be withdrawn.When concentrations higher than 2WL are indicated, the men shall bewithdrawn from the area until corrective action is taken and the radondaughter atmospheric concentrationsare reduced to 1 WL or less •..•Smoking shall be prohibited whereuranium is mined."

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4. SOURCES OF RADON AND ITS DAUGHTERS

where f is the fraction of theequilibriwn amount of RaA ions which areunattached to nuclei."

If we set f = 10%, as the ICRP indicatesmight be typical, then the occupational (MPC)ais 30 pCi/liter.

deliver all but a small fractionof the dose to the bronchi. Basedon these measured dose rates the(MPC) for exposure to radon anddaughter products is found to be

pCi 222Rn/liter of air(MPC) = 3000a (1 + 1000f)

Another source of radon is mill tailings.In some of the Rocky Mountain states, thishas been a public health problem in recentyears (Ref. 11, 12). A 1969 study indicatedthat background radon-222 concentrations infour study sites in Colorado and Utah werein the range of 0.4 to 0.8 pCi/liter. Directlyover tailings, levels higher by a factor ofabout 10 were reported, with typical spatialdistributions such that the area beyond aboutone-half-mile radius was not directly affected.

In late 1972, the ABC published proposed'remedial action criteria' (Ref. 13) for thearea around Grand Junction, Colorado. Theseare aimed at eliminating some of the moreimportant sources of exposure to the generalpublic from tailings. Remedial action wouldconsist of removal of tailings, ventilation,shielding or use of sealants; such action is"suggested" when a radon daughter concentrationexceeding 0.01 WL (or a level of 0.05 mR/hourexternal gamma radiation) is measured, and is"indicated" when 0.05 WL (or 0.10 mR/hour)is exceeded.

There is no explicit guideline for exposureof the general public to radon and its daughters.However, both the ICRP (Ref. 9) and the NCRP(Ref. 10) have recommended in their generaloverviews that individuals in the general publicbe limited to exposures at levels one-tenthas high as those for occupational exposure.Also, for a suitably large sample of thegeneral population, the general guideline isanother factor of 3 smaller still.

From the standpoint of radiological impact, the most important potential problemfrom radon and its daughters is occupationalexposure in the uranium mining industry. Thishas been discussed in detail in the section''Mining and Milling of Uraniwn Ores," elsewhere in this volwne. Here we shall swnmarizeby noting that in the U.S. a few thousandminers now require routine radiologicalmonitoring.

"Recent studies have indicatedthat when radon and its daughtersare present in ordinary air the freeions of RaA constitute only about 10per cent of the total nwnber of RaAatoms that would be present at equilibriwn and these unattached atoms

The above two standards are now consideredthe operational guidelines for exposure ofminers to radon daughters.

"Altshuler's reference atmosphere results in 60% of a 'WL dose'to the bronchi, and has a value between 10 and 30 rads per year. Inview of the ambiguities of conversion,Altshuler's reference atmosphere willbe considered, with important reservations, to produce 20 rads in anormal working year••. Exposurefor one year at. • • one WL wouldgive 33 rads. The mean organ dosewould be lower. In the absence ofan appropriate factor for the REE,the calculated dose cannot be converted to rem."

It should be emphasized that the WLstandards are based on epidemiological evidence,rather than on calculated dose equivalent tothe lungs (Ref. 7).

The absorbed dose (rad) and dose equivalent(rem) resulting from 1 WL of exposure dependupon the exact nature of the mine atmosphere.With modern ventilation procedures, the equilibriwn condition is never reached for any but thefirst daughter, RaA. Consider as an examplethe "reference atmosphere" discussed byAltshuler (Ref. 6), which contains in one literof air the following activities totaling 200pCi: 94 eCi of 218pO, 62 pCi of 214Pb, 44pCi of 21 Bi. This yields 7.4 x 104 MeV or57% of a WL. We quote from the Federal RadiationCouncil (Ref. 7):

Exposure to radiation other than theinhalation of radon daughters must be consideredseparately. The usual occupational limitsapply: that is, 5 rem/year for whole body external exposure, and so on. These limits havebeen discussed in detail in the introductorysection of this volwne (see "Radiation Guides").

A limit for radon-222 gas itself is notconsidered separately by the Federal RadiationCouncil, because of the general recognition thatthe impact of the radon daughters is the moreimportant consideration.

The International Commission on Radiological Protection (ICRP) explicitly considersthe impact of RaA in its recommendation. Wequote from ICRP Report No.6, written in 1959(Ref. 8):

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Radon occurs natumlZy in air whereveruranium-laden soils or rocks occur. Rates ofemanation and radon concentrations have beenmeasured by Pearson (Ref. 14). Near Chicago,radon was present one meter above the groundat levels which varied diurnally from about0.1 to 1.4 pCi/liter. Emanation rates inregions where 238U mining is commercially feasible were found to be larger by as much astwo orders of magnitude than rates near Chicago.(Ref. 14). However, there is not necessarilya direct correlation between emanation ratesand radon concentrations near the ground.

5. MEASUREMENT TECHNIQUES

There are four distinct classes of measurement which we shall discuss here:

i) Measurements of radon (gas)concentrations

ii) Measurements of Working Level

iii) Measurements of individualradon daughter concentrations.

iv) Working Level Dosimetry

A fifth class of measurement, discussed indetail in Volume 4 ("Biomedical Instrumentation") of this Survey, is:

v) Bioassay measurements (e.g.,urine, breath) as indicatorsof exposure or body burden.

Some of the discussion here relies heavilyon a 1972 summary of radon instrumentationwritten by A.J. Breslin of the U.S.A.E.C.Health and Safety Laboratory (Ref. 15).Another useful reference concerned with instrumentation is the 1963 IAEA Symposium(Ref. 16).

a. Measurements of Radon (Gas)

Here we shall discuss methods for measuring radon gas activity as distinct from theactivity of its daughters. This type of measurement is made by some of the more sophisticated ventilation engineers in studying mineair quality; by those concerned with naturallevels of radon gas in the air; to measureradium-226 from the emanation of its daughterradon-222; and when radon-222 is used as atracer in atmospheric studies. Methods formeasuring individual daughters will be discussedin a later sub-section.

There are two quite different approachesto the specific measurement of radon-222. Inthe first, equilibrium can be assumed to havebecome established between radon and its daughters; in the second, the daughters are removed

from the sample gas, after which either thedecay of radon itself is detected or the daughters are allowed to ingrow again for counting.

Measurements of radon activity can bemade with rather simple instruments, for routine monitoring measurements, or with quitecomplex instruments, usually used in researchapplications. We shall begin by discussingthe two simplest techniques.

The most common simple instrument formeasuring radon gas is the Lucas chamber(Ref. 17). The chamber itself is a smallmetal or glass cell with a flat glass bottom.Its shape is usually spherical but can becylindrical or conical as well. The inside islined with zinc-sulfide scintillator, and thescintillations are viewed and counted throughthe flat window by a photomultiplier tube.Filtered air samples can be drawn into thechamber using a pump, or alternatively byevacuating the chamber and then admitting afiltered sample through a valve. Typicalchamber volumes are in the 100-200 m1 range,and are thus small enough to be easily portable.Figure 4 shows the original chamber of Lucas.

KOVAR SEAL

SCINTILLATOR

QUARTZ WINDOW(CONDUCTIVE COATING)

~rl=::;::lk:=l&z:~- R-313 ADHESIVE

FIGURE 4. Lucas chamber'. Photomultiplier'tube, which views the ZnS(Ag) scintiZZationsthr'ough the qUaY'tz window, is not shown (Ref. 17).

The filter removes the radon daughtersso that only the parent radon gas is admittedto the chamber. The radon gas subsequentlydecays and reaches equilibrium with its daughters.A difficulty in the original design was optimizing and stabilizing the detection efficiencyfor the daughters, which are usually electricallycharged. When a conducting layer on the insideof the window is used, the charged daughtersturn out to distribute themselves uniformlyon the window and the ZnS(Ag) walls. (Accordingto a recent study (Ref. 18), this conductinglayer is unnecessary if the photomultiplier isoperated with a grounded photocathode.) Thealpha radiation detected by the znS(~) phosphor is a measure of the activity of 22Rn,RaA and RaC". Interferences from thoron gas(226Rn) or even actinon gas (219 Rn) are possible,since they are both also a-emitters; theseare small because of the short half-lives

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)

(55 sec for thoron and 4 sec for actinon).There are no other significant interferences.The sensitivity of the method as usually usedin the mines is about 10 pCi/liter (Ref. 15),although sensitivities an order of magnitudebetter are achievable with much longer countingtimes.

A detailed description of a techniquefor constructing Lucas chambers has geen givenin the Handbook of the EPA's Las Vegas NationalEnvironmental Research Center (Ref. 19). Also,detailed calibration procedures for Lucaschambers have been described in the APHA Standard Methods (Ref. 20), under the section~determining radiwn-226 in water by a radon-222 emanation technique.

An alternative to the Lucas chamber isthe two-filter method (Ref. 21). A metalcylinder with a filter on each end is thebasic sampling unit. Sample air is pumpedthrough th~ cylinder (typically for 5 minutesat about 10 liters/minute). The upstreamfilter removes all particles, most importantlyall radon daughters. Radon gas passes through,and inside the cylinder a small fraction decaysto 21 spo (RaA) . Some of the RaA is depositedon the downstream filter, which is immediatelycounted for alpha activity (RaA's half-lifebeing only about 3 minutes). Counting can bedone with any of a nwnber of instrwnents:

Thomas and LeClare (Ref. 21) used a ZnS(Ag)/photomultiplier system. The radon concentration must be calculated using an alge-braic expression developed by Thomas and LeClare,which depends upon geometrical sizes, samplingrate, and counting time. Using a 52-in. long,3.6-in. diameter tube, this technique issensitive at the level of a few pCi/liter;calculations indicate that sensitivities aslow as 0.1 pCi/liter could be achieved with alarger chamber, higher flow rate, and othersmall changes (Ref. 21). A variation of themethod has been used for measurements ofenvironmental radon concentrations <0.1pCi/liter, and sensitivities as low as 0.01pCi/liter are claimed (Ref. 59).

One disadvantage of this technique isthe degree of care needed in sampling, becauseof the small amount of activity present on thedownstream filter. Another is that at relativehumidities below about 25% the method hasbeen found to yield results up to almost 20%too high (Ref. 21). The reproducibility ofthe method has been studied by Breslin(Ref. 15), who finds 10% to 20% replicationerrors.

Figure 5 (from Ref. 22) shows a studyof the accuracy of the two filter method, inwhich it is compared to measurements of flasksamples analyzed in the laboratory using apulse-type ionization chamber. The averageprecision of this method was about ±20%.

1800

'-:.-<

0 16000.."00 1400..c:.....ClJ

~.... 1200ClJ~ 0~

6 1000~

E-<

E 0800

c::0.-<....'0 600........c:: r = 0.94(I)0c:: 40000c::0

"0<0

ex:

"'-)200 400 600 800 1000 1200 1400 1600 1800

Radon Concentration by Flask Method. pCi!l

FIGURE 5. Comparison of Field MeasUX'ements by the Two-FilterMethod and the Flask Method for Radon Determination

(Ref. 22).

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B

Both the Lucas-chamber and two-filtermethods appear to be satisfactory for routineuse in the uranitnn mines. A1though the standardLucas chamber technique is simpler, it doesnot have the intrinsic sensitivity of the twofilter system for research-type studies.

Another technique, with sensitivity similarto that of these methods, is the use of a pulsetype ionization chamber. A sample of gas,collected through a filter to eliminate radondaughters, is admitted to the ion chamber andallowed to come to equilibritnn before counting.This technique is described in detail in theProcedures Manual of the U.S.A.E.C. Healthand Safety Laboratory (Ref. 23).

MOre elaborate techniques have also beendeveloped for high-sensitivity studies, andthese will be discussed next.

Sensitive methods for radon sampling withcooled activated charcoal have been used formany years. At low temperatures such as thatof dry ice (-78°C), gaseous radon rapidly adsorbs on activated charcoal; radon can be subsequently de-emanated at temperatures of about300°C, collected, and counted.

The Intersociety Committee's compilationof Tentative Methods for radon (Ref. 24) describes one application of this technique.Figure 6 shows the collection apparatus.Filtered air is dehtnnidified in a dryingcolwnn (e.g., Drierite) and any remainingwater is trapped before the gas flows throughthe cooled activated charcoal. The cooling mixture is dry ice mixed with 1: 1 chloroform andcarbon tetrachloride (Ref. 25). Radon is transferred to the counting chamber along withhelium carrier gas.

MembraneFiller Holder

Inlel

DryingColumn

For counting of the gas, two differenttechniques are described by the IntersocietyCommittee (Ref. 24). In the first, theradon is transferred to a Lucas chamber, allowedto reach equilibritnn with its daughters aftera 4-hour wait, and counted. In the second,the collection trap is counted directly witha NaI (Tl) crystal, a photomultiplier, and amulti-channel analyzer. The 0.61 MeV and1. 76 MeV gammas from 214Bi(RaC) are counted,after equilibritnn has been established.

The methods are both quite sensitive.The NaI(Tl) system can detect 'V 0.12 pCi/literof radon with a ±10% error at 95% confidence(Ref. 24), while the Lucas chamber method hasbeen used to measure levels as low as about0.010 pCi/liter with errors in the ±0.005pCi/liter range (Ref. 25). The main disadvantage is, of course, that the apparatus isrelatively sophisticated, expensive, and notvery 'portable'. The NaI (Tl) gamma spectroscopy technique suffers from essentially nointerferences, and the interferences in theLucas chamber approach are also small.

Two other highly-sensitive methods usingair filters are also recommended by the Intersociety Committee (Ref. 24). Neither isapplicable for uranitnn-mine measurements.Each relies upon the existence of radioactiveequilibritnn between radon and its daughtersin the sampled air, and as such each is onlyuseful for approximate environmental measurements.

The first of these methods uses aZphaaounting. The short-lived radon daughtersare collected on a 0.8 micron pore size filter,which is nearly 100% efficient and also hasvery little self-absorption during counting.

\ Exhousl

Air FlowMeasurementInstrument

Air Mover

A: Colibroted Vocuum Type

B: Rolorneler

FIGURE 6. Sampling appar>atus for aoZZeation of gaseous airborne radon.(fPom Ref. 24)

I.....=' ' •.J

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Because the half-lives in the RaA + RaC~ chainare short, the collection and decay rates reachequilibritnn after a few hours. A 4-hour sampling time is recommended, at about 10 liters/minute. The filter is counted with a zincsulfide alpha scintillation counter and a 2"photomultiplier tube, or alternatively with aninternal gas proportional counter. The alphasfrom the two daughters RaA and RaC~ are counted.Using a counting time of 10 minutes, the lowerdetection limit is quoted as being about 0.030pCi/liter,with counting error of ±10% at 95%confidence. Interferences can occur from thelong-lived daughters of thoron e2 °Rn), butthese can be corrected for by re-counting thefil ter after a delay of 4 hours. Other alphaemitters which might collect on the filter areplutonitnn-239, 240, 238; uranitnn-238 and 235,and raditnn-226, but none of these is usuallypresent with sufficient activity to constitutean important background. Of course, the mostimportant uncertainty in this type of measurement is the asstnnption that equilibritnn existsin the air being sampled. In most environmental sampling situations, this is not trueand difficult to establish.

In the second Intersociety Committee airfilter method, beta activity is counted on thefilter (Ref. 24). Because betas are easierthan alphas to count, one can use a thicker

Window.Q.tlgjJ

Side View

Mounting ring.and windows

Polaroid 4 x 5 systemFilm holder----------»

filter and greater sampling voltnnes withoutproblems of self-absorption or dust-loading.A positive-displacement blower forces airat 500 liter/minute through a 2" glass fiberfilter. The activities to be counted arethe betas from RaE and RaC. Mter 20 minutesof sampling and 1 minute for transfer, a 10minute beta count is taken through 75 mg/cm2

of absorber using an internal gas proportionalcounter or a GM counter. A concentration of0.001 pCi/liter of radon in equilibritnn withits daughters will yield 332.2 disintegrationsof RaE and 416.9 of RaC in this time interval.A second count after 5 hours permits subtractionof possible thoron daughters. A more complexanalysis procedure uses another 10-minutecount after 1 hour to determine the RaE/RaCradio, and hence the possible extent of disequilibritnn in the original sample (Ref. 26).

Another, quite different monitor usingPolaroid film and ZnS(Ag) phosphors has beendeveloped by Bedrosian (Ref. 27). Figure 7shows the device, consisting of fast Polaroidfilm in a holder containing two ZnS(Ag) disks,one covered by filter paper and the othernot covered. The uncovered ZnS(Ag) phosphorresponds to alphas from radon gas, RaA, andRaC~ in the ambient air; the covered phosphorresponds only to alphas from radon gas, whichdiffuses through the filter. The images on

I

MOU~~ring~

Alumin~.zed•mylor 2 ,p': r1.7 mgfcm ,.~~;'Phor "C3:~j). '.:';':"~'. :.:."

I

Exploded View

Film tob

FIGURE 7. Schematic of Polaroid Land 4 x 5 film system used as aradon monitor. The film holder contains two aluminized mylar-coveredZnS(Ag) windows, one of which (A) is exposed and the other (B) coveredby filter paper. Except for the filter paper, both windows are identical and consist of elements indicated in the inset (from Bedrosian,Ref. 27).

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the film, exposed by the scintillations fromthe ZnS(Ag), are measured with a reflectiondensitometer. Bedrosian claims a ~ower limitof sensitivity for radon gas of 200 pCi/literafter 15 hours of exposure, and for radondaughters of less than 1 WL after 30 hours ofexposure. This technique shows promise wher~

levels are high, because the results are ava1lable within a few minutes after the end of anexposure, and the system is very inexpensive.Of course, it yields no information about theextent to which the ambient air being sampledis in equilibrium.

b. Working Level

Two types of Working Level (WL) measurements are required in uranium mines:

i) Measurements of WL at a giventime and place

ii) Measurements of integrated exposure either for a worker orfor a working area; these areusually expressed as WorkingLevel Hours (WLH) or WorkingLevel Months (WIN).

We shall discuss (i) here, leaving (ii) fora later sub-section.

The WL is defined as "any combination ofradon daughters in one liter of air that willresult in the ultimate emission of 1.3 x 105 MeVof potential alpha energy" (Ref. 3). Of thedaughters, RaB and RaC are beta/gamma emitters,so only the alphas from RaA and RaC" decay needbe measured. However, it must be emphasizedthat the sum energy considered in the WL contains contributions from the Rae alphas whicharise from decay of the RaA, RaB, and RaC inthe sample air. Figure 8 (from Ref. 2) showsthe growth of Working Levels in initiallypure radon.

The use of an air filter is a featurecommon to many of the methods which we shalldiscuss. The filter collects the three daughters (RaA, RaB, and RaC), after which thedecays are counted. If only alphas are counted,then what matters is the activity of RaA andRaC", the alpha-emitting dau¥hters. Figure9 (from Ref. 1) shows the bmld-up and decayof alpha activity from individu~lly is?l~t~dradon daughter isotopes, each Wlth an 1n1t1aldecay rate of 10 dpm (= 4.5 pCi).

The most common method for measuringWL is the KUsnetz method. Originally developedin 1956 (Ref. 28), it has been the mainstayof WL monitoring in the uranium mines eversince and is now recommended by ANSI as the"standard method" (Ref. 29). We shall beginby discussing it, before going on to recentor proposed improvements.

1.0,--,---,--,---,--.--,--.--,-,

0.9

0.8

0.7

0.6

o~ 0.5

8. 0.4.~~ 0.3

'"c~ 0.2

~0.1

FIGURE 8. Growth of Working Levels in initiallypure radon (e.g., freshly filtered air). Notethat the earliest contribution to WL is fromradium A, then radium B, and still laterradium C (from Evans, Ref. 2).

The Kusnetz method employs an air sampler(pump and filter) and an alpha. counter. (usuallyof the ionization chamber or zlnc-sulf1descintillation type).

The American National Standards Institutestandard method (Ref. 29) specifies samplingat 5 to 20 liters p~r minute (tpm) for fiveminutes; 10 tpm was the most common r~te atthe time ANSI 7.1 was written, producmg atotal sample volume of 50 liters. Today,'\,2 tpm is more commonly used, as we shallmention below. After a delay of from 40 to90 minutes (most comm?nly 40), the c~unt ratein counts per minute 1S measured, uS1ng arate meter. After determining disintegrationsper minute (dpm) by correcting for the efficiency of the alpha detector, a tabulate~ scalefactor is used to relate dpm to the WL 1n theoriginal sampled air.

The main feature which commends the Kusnetzmethod is its relative insensitivity to theconcentration ratios of the three daughtersRaA RaB and RaC. The intrinsic error fromnot'knowing the concentration ratios is atmost <25%. For example, suppose a 40-minutedelay"before counting; ~f RaA:RaB:RaC concentrations are in the rat10s of 100:100:100,100:90:80, 100:45:35, and 100:15:6, the in~rin

sic error in determining WL from the data 1Sonly +7%, +8%, +2%, and -7%, respectively .(Ref. 31). Groer (Ref. 32~ h~s sh?wn that mvery "young" air, such as a1r 1n.wh1ch onlyRaA has had much chance to grow m from theparent 222Rn, the Kusnetz method underestiJ;tatesthe true WL by as much as 25%. Even so, smcethese errors are smaller than typical uncertainties in the way sampling represents true

! ,.

;"b) '",

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concentration, the Kusnetz method can be saidto be intrinsically accurate enough for mostpurposes.

The minimum sensitivity of the Kusnetzmethod as just described has been studied byBreslin et al. (Ref. 22) and shown in Figure 10.

2.0

1.5

~1.0

Z .80

SC)

.5~ZinQ

~.2

.15

FIGURE 9. Build-up and deaay of alpha aativity from individualinitially isolated radon daughter isotopes, RaA through RaC,with an initial disintegration rate for eaah isolated isotope

of 10 disintegrations per minute (from Ref. 1).

30

.c:::3 2010·C10>.....o...c::.~ 10oS~o

counting error

-~:::-:::::-:::=--==--=-------- --5432

O....... -.L.. ---JL..- ....... -.JL.- ...

o

Working Level

FIGURE 10. Preaision for Measurements of Working Levelby Kusnetz Methoc1 (from Ref. 22).

I

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The precision is about ±15% at 0.3 WL but degenerates rapidly at lower concentrations.This increased error is mainly dominated bystatistical fluctuations in the rate measurement (Ref. 15) and is hence unavoidable. Afull discussion by Loysen (Ref. 33) of thevarious sources of error in the Kusnetz methodindicates that with appropriate care, errorsfrom sampling can be kept smaller than thecounting (statistical) fluctuation.

The rate-meter measurement is one sourceof error which can be improved upon, by countingfor a fixed period instead of by measuringrate. To improve the method's sensitivity,one must either sample more air or count fora longer time. In a laboratory environment,Breslin (Ref. 15) counted for four minutes(from +38 to +42 minutes) using an alphascintillation/scaler instrument. Using this"modified Kusnetz method," reproducibility wasfound to be ±4.2%, ±14%, and ±35% at mean levelsof .041, .0029, and .00046 WL, respectively.This indicates that this modified method isintrinsically sensitive enough for almost anyapplication.

There are problems with the Kusnetz method,however. The 10-~pm air pumps typically usedare heavy and cumbersome, and there has beena recent switch to smaller, lightweight 2-~pm

pumps (Ref. 31). At concentrations aboveabout 0.3 WL, the 2-~pm and 10-~pm pumps, bothsampling for five minutes, gave reasonablyreproducible and comparable results (Ref. 31).Of course, at low WL ranges the lower volumeof air sampled with the 2-~pm pump willseriously degrade the sensitivity.

Membrane filters have been most widely usedbecause of their 99+% retention of submicronparticles and because the particles are mostlydeposited right at the filter surface, minimizing self-absorption of the alphas duringcounting (Ref. 30). Glass fiber filters, equallyefficient as collectors, can suffer from morepenetration and hence more important selfabsorption corrections; but recent tests indicate that most commercial glass filters nowhave little problem with self-absorption (Ref.31). Direct moisture on the filter face cancause absorption problems for any of the filtersas well as pressure problems in pumping.

Air pump flowrneters are an especiallytricky problem because their calibration isdensity-dependent, and hence will vary if aninstrument calibrated at sea level is used atelevations well above sea level, where manyradon measurements are made. The details ofthis problem are discussed in the Bureau ofMines Handbook (Ref. 31).

An advantage of the Kusnetz method isthat the alpha-detection system, which mustrespond only to RaC~ alphas (7.69 MeV), need

not have an energy-independent response. Thedetection efficiency at that one energy mustbe known, of course. The Bureau of MinesHandbook (Ref. 31) discusses both laboratoryand field calibration procedures.

One need still awaiting a solution is thatof a good, light-weight electronic scaler.We quote from Breslin (Ref. 15): "Commercialscalers employed by mine operators have notbeen found to be satisfactory, either being tooslow in the case of mechanical counters or toobulky in the case of electronic counters."Breslin recommends the commercial developmentof an alpha counter weighing less than tenpounds, with 4-decade scaler display, 8-hourbattery lifetime before recharge, and a variablepreset timer.

Perhaps the biggest drawback of the Kusnetzmethod is the minimum 45-minute delay from startto finish. This inherent difficulty has stimulated the development of other WL techniques.

A method developed by Rolle in 1969 (Ref.34) and described further in a 1972 paper(Ref. 35) makes possible much more refinedmeasurements, using equipment identical to thatof the Kusnetz method. Rolle describes how thechoice of counting time affects systematicerror, and indicates that intrinsic errors canbe kept below about ±12% with counting for 10minutes after about a five minute wait. Rollealso discusses in detail the way volumetric andradiometric errors limit ultimate uncertaintiesto the ±20% range.

The methods just described all require aconsiderable time delay between the start ofsampling and the end of counting: the Rollemethod takes about 20 minutes, the Kusnetz upwards of 45. This has motivated the developmentof several prototype "Instant Working LevelMeters" (IWLM's).

Two different versions of such an instrument were developed in 1968-69 to provide forthe rapid, automatic measurement of WL. Themanufacturers were GeoCon Corp. (Ref. 36) andBedford Engineering Corp. (Ref. 37), the latterworking with an MIT group (Ref. 38). Neitherunit is now commercially available.

The idea of the IWLM is to count the accumulating activity as it collects on a membranefilter. The RaA and RaC~ alphas, and also thetotal beta activity, are counted with separatedetectors right next to the filter. Electroniccircuitry is used to calculate WL, which isdisplayed directly on a meter. The total timerequired for one measurement is about 4-5 minutes.

Unfortunately, Breslin (Ref. 15) indicatesthat "reproducibility, calculated from pairedmeasurements, was about ±50% for the GeoCon,and about ±100% for the MIT-Bedford. . . •

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Based on these tests, neither instrument hassufficient reliability for use in mines." Theinstruments discussed were also bulky, heavy(15-20 lb) and awkward to operate.

Further development work on an improvedIWLM is being carried on by Groer (Ref. 39)at Argonne National Laboratory. The signal/background ratio will be improved by increasing the pumping rate to 12 £'pm (for a 4-minutesample time), and by using a very thin (~O.003

inch) plastic scintillator for beta detection,to decrease background from external gammaradiation. The proposed device will calculatenot only WL, but also the three individualdaughter concentrations, using a small digitalcalculator. The hoped-for sensitivities areabout 0.01 WL and about 1 pCi/liter for eachof RaA, RaB, and RaC. If successfully developed, this instrument will be of major importance for uranium-mine measurement.

.~other development project is beingcarried out at Colorado State University bya group under Schiager (Ref. 40). A membranefilter sample is taken by manually turning apump (one liter/stroke), and WL is determinedapproximately by measuring RaA and RaC~ separately with a surface barrier detector. Nobeta radiation is measured, but WL is 'calculated' by an electronic weighting procedure:the sum (RaA + 8RaC~) or (RaA + 10 RaC~) isused as a measure of WL. Figure 11 shows howsuch a procedure yields results within tlO totlS% of WL over most of the range from equilibrium to complete disequilibrium. Prototypesare now being field-tested (early 1973). Thechief advantages, if successful, will be lightweight, ruggedness, low unit cost, and rapidityof measurement (about two minutes).

c. Measurements of Individual RadonDaughters in Air

The ability to isolate the relativeactivities of individual radon daughters inan unknown atmosphere is of great use. Inan equilibrium atmosphere, of course, all ofthe short lived daughters have activitiesequal to that of the parent; the relativeactivities are used to determine the degreeto which equilibrium has been achieved. Another measurement problem is the determinationof the "uncombined RaA fraction," that is, thefraction of RaA in the sample atmosphere whichis free and not combined with particulatematter.

Even with its short (3-minute) half-life,the first radon daughter, RaA (lI8PO), is notalways in equilibrium with the parent radon.The subsequent daughters are nearly alwaysonly partially ingrown, especially in wellcirculated air. This is true in environmentalas well as in uranium-mine atmospheres.

We have already discussed one technique(Ref. 26) for measuring the RaB/RaC ratiousing the air filter/beta counting technique.This is a complex technique which is not verysensitive unless the RaB/RaC ratio is verylarge or very small. It is not often usedfor these reasons.

Two more useful approaches are theTsivoglou method, involving several countingintervals, and the use of alpha spectroscopy.

The Tsivoglou method (Ref. 41) is one ofthe oldest techniques for radon daughter determinations. It employs an air filter and

e'f,.e~0"

.!:l .~0( Cl1:l 1:l" uc: 0.~ eH> 0u

600 800 1000

USEFUL RANGE

RaA + 8 Rae·

SOO

400..l~...

300uI:l.

:::E1:\.0U 200

8

100 'S.0;;"0""l

00 200 400

Equilibrium Index - pei RaA per WL-liter

600

FIGURE 11. Theoretical survey meter response (cpm per WL) asa function of the degree of equilibrium of airborne radon progeny(pei RaA per WL-Uter ) (from Ref. 40).

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an alpha counter/rate-meter, apparatus similarto that required by the Kusnetz method for WL,and the technical considerations required toobtain good data are similar also. One keydifference is that the alpha counter responsemust be energy-independent, which is not required in the Kusnetz method. (The Bureau ofMines Handbook [Ref. 31] discusses calibrationprocedures ln detail.) After the air sampleis taken (typically for 10 minutes at 5 ~pm),

the alpha count rate is measured at threelater times: after delays of 5, 15, and 30minutes. RaA, RaB, and RaC concentrationsare then determined by solving three simultaneous equations.

Unfortunately, studies by Breslin et al.(Ref. 22), with 100-liter sample volumes atconcentrations of 0.5 to 5 WL, indicate thatreproducibility is poor for identical repeatmeasurements: RaB/RaA ratios and RaC/RaAratios had replication errors in the 15-25%and 25-35% ranges, respectively.

This problem has motivated work on improvements in the method. The simplest improvement is similar to the way the originalKusnetz method can be improved: use of counttotals rather than count rates. Thomas (Ref.42), using a five minute sampling time at10 ~pm, has taken count totals in three timeintervals: 2 to 5, 6 to 20, and 21 to 30minutes. He is able to express RaA, RaB, andRaC concentrations directly in terms of thethree count totals: essentially, the simultaneous equations are solved and the matrixinverted. The precision of the determinationsis good according to calculations. QuotingBreslin (Ref. 15): "At. . . 0.3 WL and aradon daughter ratio of 100:30:10, •.. thecalculated precisions for RaA, RaE, and RaCmeasurements are 4%, 4%, and 12%, respectively.

This modified-Tsivoglou technique can alsobe used for WL measurements, and the resultsare comparable to those obtained with themodified Kusnetz method. However, because ofthe added complication, the method is probablynot to be preferred when WL measurements aloneare required, unless accuracy is at a highpremium.

A theoretical analysis of the Tsivogloumethod, extending the treatment to any numberof general counting times, has been given byMartz et al. (Ref. 43).

Alpha spectroscopy is another usefulapproach for measuring individual radon daughter concentrations. Instead of using theair filter/alpha counting technique, one cansubstitute an alpha spectrometer for the alphadetector system. Several types of alpha spectrometers have been developed, all of whichhave been described elsewhere in this volume(see "Alpha Particle Instrumentation"). The

best resolutions are now obtainable withsolid state detector systems. The alpha linesrequiring resolution and measurement haveenergies of 6.00 MeV (RaA) and 7.69 MeV (RaC~).

The method developed by Martz et al.(Ref. 43) uses a solid-state detector andmultichannel analyzer, with a 4.3-~pm collectionrate onto a membrane filter. Separate determinations of the RaA and RaC~ alpha activitiesare made at two times, 5 and 30 minutes aftersampling. This leaves only two simultaneousequations (compared to the three required inthe Tsivoglou method) to determine the relativedaughter concentrations.

The main advantage of this method is itsimproved accuracy in determining the shortlived (3-min) RaA: the RaA alpha is counteddirectly. In experimental comparisons withthe Tsivoglou method, Martz et al. (Ref. 43)found that the spectroscopic method was significantly more precise for both RaA (8% standarddeviation compared to 29%) and RaC (14% compared to 27%), and comparable for RaB (12%).This approach thus appears to be promising,albeit one requiring more expensive and elaborate instrumentation. It is obviously possibleto use alpha spectroscopy in uranium mines,but this is probably difficult because of theinconvenience. The better accuracy for RaAwould tend to be nullified by the delay intaking mine samples out to surface countingequipment, and hence this technique is probably most applicable to environmental samples.

A more complicated analysis techniquehas been developed by Raabe and Wrenn (Ref. 44),who generalize the Tsivoglou method by performing a regression analysis to fit mathematically the observed count totals duringvarious counting periods. Thus one would notbe limited to three count periods and threesimultaneous equations. Also, simultaneousdeterminations of thoron daughters are possible.Measurements with the system over 7 time intervals (the last 3 hours after taking a oneminute, 7.5-liter sample) are clearly moreaccurate than those of the Tsivoglou method,but the complicated analysis is probablyonly useful when research work requires highsophistication and accuracy.

Before leaving the subject of individualradon daughter measurements, a brief discussionof "uncombined RaA fraction" determinationswill be given. The ICRP (Ref. 8) has notedthat the fraction of RaA which is not combinedwith particulate matter seems to playa majorrole in the radiobiological impact of theradon daughters. One possible explanationfor this is that they are exceedingly active,owing to their high diffusion velocity. Thishas inotivated attempts to measure this uncombined fraction (f). These measurements aremostly performed for research purposes ratherthan in routine monitoring.

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Duggan and Howell (Ref. 45) describe asystem in which two filters sample the atmosphere side by side. One of them is "precededby a diffusion battery designed to remove mostof the unattached daughters but hardly any ofthe attached ones" (Ref. 45). RaA is distinguished from RaC~ by alpha spectroscopy. Another method has been described by Fusamuraand Kurosawa (Ref. 46), in which gas ispassed through a diffusion tube, and thediffering diffusion coefficients are reliedupon to bring about a partial separation.In this way, f-values in the range 6 to 25%were measured to within better than a factorof 2. Another device based on diffusion hasbeen described by Mercer and Stowe (Ref. 47).It is shown in Figure 12 (from Ref. 48)."Air enters through an orifice in the centerof the upper of two discs and flows radiallyoutward between the discs and down past theedge of the lower disc" (Ref. 48). As much as80% of unattached RaA atoms (and typically60 to 70%) can be collected on the discs(Ref. 47). Using this system, George andHinchliffe (Ref. 48) measured f-values below0.10 with precisions in the range of ±0.007to ±0.014.

d. Personnel Dosimeters

The usefulness of Working Level dosimetry for occupational workers is obvious:a portable instrument which could accuratelyintegrate WL exposure over tune would help toprovide for the radiological protection of anyoccupationally exposed individuals (e.g.,miners). Present dosimetry is done by measuring WL and correlating with the amount of timespent in each of the various working areas bya worker. This present method has, of course,served a valuable purpose over a long period,and has certain advantages over dosimeters,among which are that measurements are made bytrained personnel with less inconvenience forthe miner. In any event, such WL measurementswill always be required to supplement a personnel dosimetry system even if it achievedwide acceptance.

The requirements of a personnel dosimeterare that it should be sensitive down to anintegrated exposure of, say, less than about1 WL-hour; that it be capable of weekly orbi-weekly readout; that it properly samplethe air being breathed; and that it be light,rugged and failsafe.

A number of development efforts in recentyears have been directed toward this problem.White of the U.S.A.E.C. Health and SafetyLaboratory performed three sets of evaluationsof several of the dosimeters (Ref. 49, 50, 51),which Breslin (Ref. 15) has summarized. Thevarious dosimeters employed different kindsof detectors: some had pumps and filtersand some sampled passively; some were sensitive

AIR INLET

AIR OUTLET

FIGURE 12. Diffusion sampler for unaombinedradon daughters (from Ref. 48).

to radon gas, some to the radon daughters, andone to both. Their properties are given inTable 2.

White' s tests of the two dosimeters designed to measure radon gas showed that neitherperformed satisfactorily in laboratory standardization tests (Ref. 49). One of thesewas an alpha-track-count film detector fromEberline (Ref. 52), the other a 2nS(Ag) scintillator with film recording from NYU (Ref.53). One gave responses which varied by factors of as much as 10 when repeat runs weretaken; the response of the other varied by afactor of as much as 3, but the dosimeteronly increased its response by a factor ofabout 3 when radon concentrations increasedby a factor of 10.

Of the six dosimeters responsive toradon daughters (or radon gas plus daughters),the responses of 5 were judged to be muchpoorer than 'satisfactory' (Ref. 49, 50, 51).The best performance was that of the HASLdosimeter, called the ''MOD''. The reason forthis is partly that the MOD's design occurredlater than, and was able to profit from, thedesigns of some of the others.

There were a variety of reasons for thepoor performances of the other dosimeters.These are the units from Oak Ridge (Ref. 54),MIT, Colorado State University (Ref. 55),and General Electric (Ref. 56, 57). In themine tests, the harsh conditions of use(mechanical abuse, high humidity, corrosionproblems, mud on the detectors and filters,pump failure) caused many problems. Formost of the unsatisfactory units, reproducibility was poor; and the results of a comparison study (in which two similar unitswere worn together by the same miner) werealso poor.

I

~I

$: .."o 0 zz :c en:::j m :rio z c~ ~ sz :c mG) 0 z

Z -l

S »m -l

Z 0-l Z»r

Total Period ofWgt. Operation

EffectiveRange of

Pump AirFlowLocation

TABLE 2.

Radon Dosimeters

Type ofDetector

AtmosphericCanponentRef.Source--- - Ptmm Detector (liters/min Measurement (oz) (hours)

Health & Safety Lab. 51 Rn dtrs TID belt hat 0.100 3 - 1000 WL-hr 28 > 9(LiF)

Oak Ridge Natl. Lab. 51, 54 Rn dtrs atrack etch hat hat 0.021 1 - 400 WL-hr 2 >13

Mass. lnst. of Tech. 50 Rn dtrs TID belt hat 0.100 .026 - 2 x 105 WL-hr 7 9(CaF2:Dy)

Colo. State Univ. 49, 55 Rn dtrs TID belt hat 0.170 .025 - 6 x 106 WL-hr 24 40(LiP)

Eberline lnst. Co. 49 Rn dtrs atrack cmmt belt belt 0.015 4 - 600 W1-hr 12 10

General Elect. Co. 49, 56 Rn and atrack etch hat passive 5 - 100 WL-hr <1 unlimitedRn dtrs --

Eberline lnst. Co. 49, 52 Rn atrack cmmt -- hat passive 4 - 1000 pCi-hr 1 unlimitedcc

New York Univ. 49, 53 Rn scint. +film -- -- passive 10 - 200 pCi-hr 4 unlimitedcc

'"d\l>~~\l> :::l \l>OQ 0-0 p..(l) 0 I

t:i::lZ...... \l> I c::oo~ Nn

OQN::>"Nc...,rt

\l> (l)::l '"i• Vl

......<D~

VI

I'"

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RAD-NUeRadon-222and DaughtersPage 19 Jan. 1973

Unfortunately, the performance even ofthe MOD dosimeter was still less than fullysatisfactory in White's last test (Ref. 51).Figure 13 (from Ref. 51) shows White's minedata, comparing response to WL-hours of exposure. The paired measurements joined byvertical lines denote data from duplicate dosimeters worn by the same miner. Among theproblems was the pump, which was specially redesigned after the experience with the earlierdosimeters, but which still suffered fromoccasional leakage of dirt into the pump casing.Also, dosimeter response to external (betaand gamma) radiation was a problem. Bothof these can be corrected, the latter by useof a normal TLD dosimeter to measure the beta-

gamma background. The replication error ofthe MOD dosimeter was about 15%. Work is nowunderway at HASL (Ref. 15) to improve the pumpstill further.

A research program on radon dosimetrybased on an alpha track-etch method is nowgoing on under Benton at the University ofSan Francisco (Ref. 58). This approach issimilar to that used in the General Electricdosimeter (Ref. 56), one of those tested andfound unsatisfactory by White (Ref. 49).Small plastic polymers have been successfullyused for dosimetry in space applications, andBenton's project hopes to improve theirapplicability in uranium-mine dosimetry.

30r-----------------.,---,o-t

/

Log ,R = •12 + • 85 Log Er = .89

10

.....c

I0-1

~.Q)tilc: y00.tilQ) /.0::

3

Least Squares Line and 95% ) /Confidence Bands from StandardizationRuns

/~

3010

1 '-- .-"- --1...... --'

1 3

E~posure,WL-hr

FIGURE 13. MOD Dosimeter - Mine Data (from Ref. 51). The pairedmeasurements joined by vertiaal lines denote data from dupliaatedosimeters worn by the same miner. The solid line shows the leastsquares best fit. The dashed lines show the mean and 95%-aonfidenaelevel from laboratory standardization runs.

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In this section, we have attempted tooutline the various techniques for measuringradon-222 and its daughters in uranium minesand in environmental media. There are severalquite different measurement problems, and weshall summarize the situation in each areaseparately:

On the other hand, the assessment ofoccupational integrated exposure will probablybe performed for some time to come by combining WL area measurements with worker areatime records. Thus the premium on a rugged,reliable, accurate and rapid instrument isstill important.

a) Radon as Gas c) Individual Radon Daughters

Two simple methods exist for radon measurements in the concentration range down tobelow 10 pCi/liter. These are the Lucas chamber (Ref. 17) and two-filter method (Ref. 21).Both appear to be satisfactory for routine usein the uranium mines, and each can be modifiedfor sensitivities below 1 pCi/liter. For environmental measurements, where sensitivitieswell below 0.1 pCi/liter are sometimes required, several more elaborate methods havebeen developed. The situation appears to besatisfactory, since the elaborate methods,usually used only in research applications,probably do not merit significant improvementeffort at this time.

b) Working Level Measurement

The Kusnetz method (Ref. 28), used formany years as a standard technique in theuranium mines, is not sensitive enough tomeasure WL in the range below about O. 3 WL.The 'modified Kusnetz method' (Ref. 15) andthe method developed by Rolle (Ref. 34, 35)are both sensitive enough (~ 0.01 WL) to meetalmost any need. Unfortunately, although theother components of the measurement system areavailable, there does not yet exist an alphacounter-with-scaler adequate to the task foruse in the mines. Furthermore, neither ofthe methods gives an immediate answer, thedelays being about 45 minutes (modified-Kusnetz)and 20 minutes (Rolle).

A more rapid WL monitor has still not beensuccessfully developed, although some progressin this regard has occurred recently. In particular, the development project under Schiager(Ref. 40) may soon produce an instrument whichis portable, simple, and inexpensive (althoughnot as accurate as might ultimately be desired).Also, the development project under Groer(Ref. 39) shows great promise for the combinedmeasurement of WL and individual daughter concentrations.

One point which must be borne in mind isthat the total market even for an excellentWL meter is probably quite limited, so thatcommercial exploitation might not occur oncean instrument is developed.

A number of methods, all variations uponthe long-established Tsivoglou technique (Ref.41), rely upon measuring activity collectedon an air filter. To determine the activityratios of several daughters, several measurements at different times (after collection)are required. The most precise of these techniques, that of Martz et al. (Ref. 43), usesalpha spectroscopy instead of alpha counting.

The usefulness of instruments of thistype is undisputed, but their value is tomining ventilation engineers rather than forbroad-based radiological monitoring. Unfortunately, this is a small market, which wouldprobably not merit the commercial developmentof a fully-automatic instrument. Such an instrument might have a pre-set clock to measurethe air sample at the appropriate times; andit might calculate the RaA/RaC and RaA/RaBratios automatically, as well as the WL value.This seems like an instrument easy to designand build but unlikely to be developed inthe near future. Alternatively, the development project under Groer seems possibly capable of filling this need, since the instrument is designed to yield individual radondaughter concentrations down to the level of1 pCi/liter.

d) Personnel Dosimeters

The MOD dosimeter under development atHASL (Ref. 51) seems to be on the verge ofsuccess, in which case it should be given extensive field tests in the mines. The factthat several other prototype dosimeters didnot operate satisfactorily should not discouragefurther attempts, since some of the other techniques deserve another try. In particular,the polymer alpha-etch technique being studiedby Benton (Ref. 58) seems capable of possibleapplication, as does the Oak Ridge alpha trackcount technique (Ref. 54).

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RAD-NUCEadon-222and DaughtersPage 21 Jan. 1973

In conclusion, much instIUlTlentation inthis area of measurement is less than satisfactory. We have attempted to illustratethose techniques which show the greatest promise for further exploitation, but ultimatelythe problem with all of the instruments isthat their expense will limit their use, andtheir limited potential use will discouragecommercial development -- unless use of aninstIUlTlent is mandated by the Bureau of Mines.Finally, the need for instIUlTlents which aresimple to operate in the mines must be emphasized, since the general lack of skillamong many mine monitoring personnel is recognized by all.

7. ACKNOWLEDGMENT

For this section we particularly acknowledge the generous advice and review of:

Alfred J. Breslin, U.S.A.E.C. Healthand Safety Laboratory

Peter G. Groer, Argonne NationalLaboratory

George A. Morton, Lawrence BerkeleyLaboratory

Keith J. Schiager, Colorado StateUniversity

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8. REFERENCES


1.

2.

3.

4.

5.

6.

7.

U.S. Public Health Service, Control of Radon Dau htersBiologic Effects, U.S.P.H.S.~~l~l~c~at~l~o~n~N~o~."'~~~~~~~~~~~~~~~~~~~

R.D. Evans, "Engineers' Guide to the Elementary Behavior of Radon Daughters," Health Physics17, 229 (1969).

R.L. Rock, D.K. Walker, R.W. Dalzell and E.J. Harris, ContrOllin~ ~lOyee Exposure to AlphaRadiation in Underground Uranium Mines, U. S. Bureau of Mines Han boo Volumes I and II(1970 and 1971).

Federal Register, Vol. 33, No. 252, December 28, 196a

Federal Register, Vol. 34, No. 11, January 16, 1969.

B. Altshuler, N. Nelson and M. Kuschner, "Estimation of the Lung Tissue Dose From Inhalationof Radon and Daughters," Health Physics 10,1137 (1964).

Federal Radiation Council, Guidance for the Control of Radiation Hazards in UraniumMining, Report FRC No.8 (revIsed), WashIngton, D.C. (1967).

8. ICRP Pub. 6 (as amended 1959 and revised 1962). Pergamon Press, 1964.

9. ICRP Pub. 2: "Report of Committee II on Permissible Dose for Internal Radiation." PergamonPress, 1959.

10. Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides inAir and in Water for Occupational Exposure, NatIonal Bureau of StandardS Handbook 69.Washington, DC (1959).

11. S.D. Shearer and C.W. Sill, "Evaluation of Atmospheric Radon in the Vicinity of Uranium MillTailings," Health Physics, E, 77 (1969).

12. "Evaluation of Radon-222 Near Uranium Tailings Piles," Report DER 69-1, U.S. Bureau ofRadiological Health, Rockville, MD 20852 (1969).

13. "Grand Junction Remedial Action: Proposed Criteria," U.S.A.E.C. proposed standard, FederalRegister 37, No. 203, 19 October 1972.

14.. J.E. Pearson, "Natural Environmental Radioactivity from Radon-222," U.S. Public HealthService Pub. No. 999-RH-26 (1967).

15. A.J. Breslin, ''Monitoring Instrumentation in the Uranium Mining Industry," unpublished report(1972). Available from U.S.A.E.C. Health and Safety Laboratory, 376 Hudson Street, NewYork, NY 10014.

16.

17. H. F. Lucas, "Improved Low-Level Alpha Scintillation Counters for Radon," Rev. Sci. Inst.28, 680 (1957).

18. J. Kristan and I. Kobal, "A Modified Scintillation Cell for the Determination of Radonin Uranium Mine Atmosphere," Health Physics 24, 103 (1973).

19. F.B. Johns, "Southwestern Radiological Health Laboratory Handbook of RadiochemicalAnalytical Techniques," Report SWRHL-ll (1970). Available from SWRHL, now EPA NationalEnvironmental Research Center, Las Vegas, NY 89114. .

20. Standard Methods for the Examination of Water and Wastewater, 13th Edition, AmericanPublic Health Association, 1015 - 18th St., N.W., Washington, DC 20036 (1971).

21. J.W. Thomas and P.C. LeClare, "A Study of the Two-Filter Method for Radon-222,"Health Physics 18, 113 (1970).

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22. A.J. Breslin, A.C. George and M.S. Weinstein, "Investigation of the RadiologicalCharacteristics of Uranium Mine Atmospheres," Report HASL-220, U.S.A.E.C. Health andSafety Laboratory, 376 Hudson Street, New York, NY 10014 (1969).

23. J.H. Harley (editor), HASL Procedures Manual, Report HASL-300, U.S.A.E.C. Health andSafety Laboratory, 376 Hudson Street, New York, NY 10014 (1972). Earlier editions ofthis Manual were published as Report NYO-4700.

24. Methods of Air Sffiling and Analysis, Intersociety Corranittee for a Manual of Meth8ohds

Sfor

Aiiib1ent Au Sarnp mg and Analys1s. American Public Health Association, 1015 - 1 t treet,N.W., Washington, DC 20036 (1972).

25. G.E. Jones and L.M. Kleppe, "A Simple and Inexpensive System for Measuring Concentrations ofAtmospheric Radon-222," Report UCRL-16952, tmpublished (1966). Lawrence Berkeley Laboratory,Berkeley, CA 94720.

26. L.B. Lockhart, R.L. Patterson, and C.R. Hosler, "Determination of Radon Concentrations in theAir through Measurement of Its Solid Decay Products," Report NRL-6229 (1965), and "The Extentof Radioactive Equilibrium Between Radon and Its Short-Lived Daughter Products in theAtmosphere," Report NRL-6374 (1966). U.S. Naval Research Laboratory, Washington, DC.

27. P.H. Bedrosian, "Photographic Technique for Monitoring Radon-222 and Daughter Products,"Health Physics 16, 800 (1969).

28. H.L. Kusnetz, "Radon Daughters in Mine Atmospheres: A Field Method for Determining Concentrations," Am. Ind. Hyg. Assn. Quarterly 17,85 (1956).

29. ANSI N7.l, "Radiation Protection in Uranium Mines and Mills (Concentrators)," AmericanNational Standards Institute, 1430 Broadway,New York NY 10018 (1960). This is tmder revisionand will soon be superseded by ANSI N13.l (Ref. 30).

30. ANSI N13.l, "Radiation Protection in Uranium Mines," American National Standards Institute,1430 Broadway, New York, NY 10018 (1972).

31.

32. P.G. Groer, ''The Accuracy and Precision of the Kusnetz Method for the Determinatioh ofthe Working Level in Uranium Mines," Health Physics 23, 106 (1972).

33. P. Loysen, "Brrors in Measurement of Working Level," Health Physics 16, 629 (1969).

34. R. Rolle, "Improved Radon Daughter Monitoring Procedure," Am. Ind. Hyg. Assn. Journal ~,

153 (1969).

35.. R. Rolle, "Rapid Working Level Monitoring," Health Physics ~, 233 (1972).

36. GeoCon, Inc., 71 Rogers Street, Cambridge, MA 02142.

37. Bedford Engineering Corporation, Bedford, MA.

38. G.L. Schroder and R.D. Evans, Instrumentation for In-Mine Instant Measuring of Working Leveland Radon Concentrations, '~assaChusetts Inst1tute of TeChnology Annual Progress Report952- 5," Part 1, Boston, MA (1968).

39. P. Groer, Argonne National laboratory (private cOnnlltmication).

40. K.J. Schiager, "Radon Progeny Inhalation Study," Colorado State University Report, COO 1500-17(February 28, 1970). Available from K. Schiager, Colorado State University, Ft. Collins, CO. 80521

41. E.C. Tsivoglou, H.E. Ayer and D.A. Holaday, "Occurrence of Nonequilibrium Atmospheric Mixturesof Radon and Its Daughters," Nucleonics 11, 40 (Sept. 1953).

42. J.W. Thomas, '~easurement of Radon Daughters in Air," Health Physics Q, 783 (1972).

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43.

44.

~5.

46.

47.

48.

49.

50.

51.

52.

53.

54.

55.

56.

57.

58.

59.

D.E. Martz, D.F. Holleman, D.E. McCurdy and K.J. Schiager, "Analysis of Atmospheric Concentrations of RaA, RaB, and RaC by Alpha Spectroscopy," Health Physics 11., 131 (1969).

O.G. Raabe and M.E. Wrenn, "Analysis of the Activity of Radon Daughter Samples by WeightedLeast Squares," Health Physics 11.,593 (1969).

M.J. Duggan and D.M. Howell, ''The Measurement of the Unattached Fraction of AirborneRaA," Health Physics 12, 423 (1969).

N. Fusamura and R. Kurosawa, "Determination of f-Value in Uranium Mine Air," p. 213 inAssessment of Airborne Radioactivity, International Atomic Energy Agency, Vienna (1967).

T.T. Mercer and W.A. Stowe, "Deposition of Unattached Radon Decay Products in anImpactor Stage," Health Physics 17, 259 (1969).

A.C. George and 1. Hinchliffe, ''Measurements of Uncombined Radon Daughters in UraniumMines," Health Physics Q, 791 (1972).

O. White, Jr., "An Evaluation of Six Radon Dosimeters," Report HASL TM 69-23A (1969).Available from U.S.A.E.C. Health and Safety Laboratory, 376 Hudson Street, New York, NY 10014.

O. White, Jr., "Evaluation of MIT and ORNL Radon Daughter Dosimeters," Report HASL TM 70-3(1970). Available from U.S.A.E.C. Health & Safety Laboratory, 376 Hudson St., New York, NY 10014.

O. White, Jr., "Evaluation of MOD and ORNL Radon Daughter Dosimeters," Report HASL TM 71-17(1971). Available from U.S.A.E.C. Health & Safety Laboratory, 376 Hudson St., New York, NY 10014.

E.L. Geiger, "Radon Film Badge," Health Physics 13, 407 (1967).

C. Costa-Ribeiro, J. Thomas, R.T. Drew, M.E. Wrenn, and M. Eisenbud, "A Radon DetectorSuitable for Personnel or Area Monitoring," Health Physics 17, 193 (1969).

J .A. Auxier et a1., "A New Radon Progeny Personnel Dosimeter," Health Physics l!., 126 (1971).

D.E. McCurdy, K.J. Schiager, and E.D. Flack, "Thermoluminescent Dosimetry for PersonalMonitoring of Uranium Miners," Health Physics 17, 415 (1969).

D.B. Lovett, "Track Etch Detectors for Alpha Exposure Estimation," Health Physics 16, 623 (1969).

R.1. Rock, D. B. Lovett, and S.C. Nelson, "Radon-Daughter Exposure Measurement with Track-Etch Films," H€/3.lth Physics 16, 617 (1969).

E.V. Benton, University of San Francisco (private communication).

H. Newstein, L.D. Cohen, and R. Kablin, "An Automated Atmospheric Radon Sampling System,"Atomic Environment~, 823 (1971).

0 ,,) ;.).0

01

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RADIUM

1. Introduction

2. Physical Characteristics


4. Sources of Environmental Radium

S. Measurement Considerations

RAD-NUCRadiumPage 1June 1973

a. Radon Emanation Techniquesb. Sample Preparation for Radon Emanationc. Radiochemistry with Radium Alpha Countingd. Radiochemistry with Counting of Radium Daughters

6. Calibration Sources


8. Acknowledgment

9. References

L.,.' '.. '_ ',,' ,!'.' 'j • •" . . U ,) 0" .;; /

L

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INTRODUCTI ON

RAD-NUCRadilUllPage 3

2. PHYSICAL CHARACTERISTICS

RadilUll is, of course, perhaps the mostpopularly familiar of all the radioactiveelements. Its use in cancer radiotherapywas one of the earliest "miracles" among theapplications of nuclear physics, and itstoxicity when taken internally is equallywell-known, from the case of the radilUll watchdial painters.

In this section a discussion will begiven of the measurement of radilUll concentrations in environmental media, primarily forenvironmental radiological protection. Weshall concentrate on methods for determininglow levels of radium in water and certainfood-chain media, but shall not treat in detail bioassay methods, which are covered inVollUlle 4 ("Biomedical Instrumentation") ofthis Survey. While the main emphasis will beon radilUll-226, the other important isotopes(223, 224, 228) will be discussed whereappropriate.

First a review of the physical characteristics of the important radium isotopes willbe given; next, the radiation protectionguides for radium concentrations will be discussed, and the ranges of radium-226 concentrations in the natural environment will bepresented. Various radium measurement techniques will then be discussed.

Discussions which are important for amore complete picture of the measurement techniques dealt with in this section are foundin two other sections of this VollUlle. Thesesections are "Radon-222 and Its Daughters,"in which the uranilUll-238 decay chain and theinstrumentation for radon-222 measurementsare discussed; and "Alpha Particle Instrumentation," in which instruments for detectingalphas are treated in detail.

RadilUll occurs naturally in four isotopicstates, each of which is a member of anaturally-occurring decay chain:

(1) Radium-226 (half-life = 1602 years)is a member of the uranilUll-238 chain. Itsimmediate parent is the alpha-emitter thorium230 (80,000 years) and its daughter is theinert gas radon-222 (3.82 days). The 226Radecay to 222Rn is by alpha-emission (94.6% ofthe decays by a 4. 78-MeV (Y,; the remaining5.4% by a'4.60-MeV (Y, followed by a l87-keVgamma).

(2) RadilUll-223 (half-life = 11.4 days)is a member of the uranium-235 chain. Itsimmediate daughter is radon-219 (half-life =4.0 seconds), an inert gas known historically as 'actinon'. The 22 3Ra decay to 219Rnis by alpha emission. The most important (Y,

energies and branching ratios are: 5.75-MeV(9%); 5.71-MeV (52%); 5.6l-MeV (25%); 5.54-MeV(9%). Each (Y, is acco~anied by a gamma beforethe ground state of 21 Rn is reached.

(3) RadilUll-228 (half-life = 6.7 years)is a beta-emitting member of the thorium-232chain. Its low energy beta (Emax = 55-keV)leads to actinilUll-228 (6.1 hours), which inturn beta-decays to thorium-228 by one of alarge nlUllber of beta energy spectra, the mostenergetic of which is 2.15 MeV. ThorilUll-228(1.9 years) then decays by (Y, emission (5.4 MeV)to radilUll-224.

(4) RadilUll-224 (half-life = 3.64 days)decays by (Y, emission to the gas radon-220,historically 'thoron' (55 sec). The decayproducts are a 5.68-MeV alpha (94%) or a5.44-MeV (Y, followed by a 24l-keV gamma (6%).

This infonnation is summarized in Table 1(information taken from Ref. 1)

TABLE 1.

Some PhysicaZ Properties of Radium Isotopes (from Ref. 1)

Member of Which Immediate Main Decay Products and EnergiesIsoto e Half-Life Deca Chain Parent for fl E )

ranc lngRatio Decay Products

Radiwn- 223 11.4 days U-235 chain Thorium-227 Radon-219 ( 9%) 5;75-MeV a + 338-keV y(18.2 days) (4.0 sec) (52%) 5. 71-MeV a + 270-keV y

(25%) 5.61-MeV a + 154-keV y( 9%) 5. 54-MeV a + 122-keV y

Radium-224 3.64 days Th-232 chain Thorium-228 Radon-220 (94%) 5.68-MeV a(1.9 years) (55 sec) ( 6%) 5.44-MeV a + 241-keV y

Radiwn-226 1602 years U-238 chain Thoriwn- 230 Radon-222 f94.6%~ 4.78-MeV a(80,000 years) (3.82 days) 5.4% 4.60-MeV a + 187-keV y

Radiwn- 228 6.7 years Th-232 chain Thoriwn-232 Actinium-228 (100%) 55-keV (max) fl(14 billion (6.1 hours)

years)

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Chemically, radium is an alkaline earthelement in the same family with magnesium,calcium, strontium, and barium. Its chemicalsimilarity to calcium leads to its principaltoxic effect, the preferential lodging in boneupon ingestion.

An interesting historical note is that1 curie was ori~inally defined as the activityof 1 gram of 22 Ra. Small shifts in the definitions have occurred since then, so that nowradium-226's specific activity is about 0.988Ci/gram. However, today radium-226 is stillsometimes measured in, for example, pg/literinstead of pCi/liter . . • these are numerically almost equal.


Radium's toxicity depends upon whetherits form is soluble or insoluble. ~~en

radium-226 is soluble, for example, it is amuch more severe problem upon ingestion bymouth. These differences have been taken intoaccount in the establishment of the radiationprotection guides.

For l68-hour occupational exposures, theInternational Commission on Radiological

Protection has established maximum permissibleconcentrations in air and water OMPC)a and(MPC)w; these are given in Table 2, from ICRPPublication 2 (Ref. 2). The maximum permissible body burdens (MPBB) are also given.Note that for individuals in the general public,the applicable (MPC) values are a factor of10 smaller than those tabulated in Table 2;and for exposure to a suitably large sampleof the general public, another factor of 3smaller still.

With that factor of 30 reduction, the(MPC)w for soluble 226Ra in drinking waterfor a large population would be 100/30 =3.3 pCi/liter. The 1962 U.S. Public HealthService Drinking Water Standard (Ref. 3)adopts that very value (actually, 3.0 pCi/liter) as its recommended limit. The P.H.S.recommends "gross-alpha" measurements forroutine screening of water samples; specificanalyses for radium is only required if grossalpha exceeds 3 pCi/liter. Gross-alpha measurements, which can be performed using any ofseveral well-established methods, are discussed elsewhere in this Volume ("Alpha ParticleInstrumentation").

TABLE 2.

168-Hour/Week Occupational Maximum Permissible Concentrations in Air and Water.

and Maximum Permissible Body Burdens (from ICRP Pub. 2. Ref. 2)

Isotope Soluble or Critical (MPC)w (MPC)a MPBBInsoluble Organ pCi/liter pCi/liter pCi

Radium-223 soluble bone 7,000 0.6 50,000

Radium-224 soluble bone 20,000 2.0 60,000

Radium-226 soluble bone 100 0.01 100,000

Radium-228 soluble bone 300 0.02 60,000

Radium-223 insoluble lung 0.08GI (LLI) 40,000

Radium-224 insoluble lung 0.2GI (LLI) 50,000

lung *Radium-226 insoluble GI (LLI) 300,000\

Radium- 228 insoluble lung 0.01 ~,~)

GI (LLI) 300,000

*Bernard and Ford (Ref. 4) recommend a value of 0.02 pCi/liter.

GI(LLI) refers to gastrointestinal tract (lower large intestine).

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4. SOURCES .AND LEVELS OF ENVIRONMENTAL RADIUM

Wherever uranium or thorium occurs naturally in the environment, the various radiumisotopes will inevitably be found as well.Generally, the decay of the parents in thechain will proceed down through several steps,during all of which time the heavy nucleus willusually remain immobile in the original location. Each of the decay chains ultimatelyleads to one of the radons (222, 220, 219),and these gases can and do migrate. Theyemanate from surface layers or liquids, andare one of the more prominent external manifestations of the natural radioactivitypresent.

Another important migration mechanism isleaching: Water-soluble or reactive membersof the chain, including radium, can be leachedout into the ground water. This leaching isa significant radiological effect in some areas.For example, although radium-226 concentrationsin domestic tap water are typically in therange from 0.01 to 0.2 pCi/liter (Ref. 5),concentrations in the range of 1 to 5 pCi/literoccur in several areas and concentrations inthe 10 to 50 range are occassionally found(Ref. 7). Because of the shorter half-livesof the other radium isotopes, the long-lived2Z6Ra is the dominant isotope. However, 22 8Raand 224Ra are sometimes found at levels comparable to those of 226Ra (Ref. 8).

Radium enters the human food ahain inmany ways. Plant uptake of radium directlyfrom the soil, or from the water, producessmall but measurable radium concentrations infoods. For example, a 1969 hospital dietstudy in California (Ref. 9) found daily percapita intakes of 226Ra in food in the rangeof 0.5 to 2 pCi/day. Studies in Italy (Ref.10) of food from sources not known to be artificially contaminated showed the followingapproximate specific activities for radium226: 0.4 pCi/kg in fruits; 0.4 to 0.7 pCi/kgin potatoes; 0.7 to 1.2 pCi/kg in green vegetables and lettuce; 3.6 to 3.8 pCi/kg in flour;and 5.8 to 6.9 pCi/kg in eggs.

In air, concentrations of radium itselfare usually minute. Mechanisms which mightproduce airborne (particulate) radium concentrations would probably include such localeffects as duststorms. Studies of airborneradioactivity (Ref. 11, 12) do not mentionradium at all. Of course, the emanating gases(radon-222, 220, 219) and their daughters arewidely distributed in measurable concentr?tions.

In soiZs, radium concentrations vary ina way correlated with the natural uranium/thorium content. Pearson (Ref. 13) found226Ra concentrations in the range of 0.1 to0.8 pCi/gram (dry soil), in several samples

scattered through the U.S., but as high as15 pCi/g in uranium mining areas. In uraniumores, the 238U/235U atomic ratio is constantat about 138.5/1 (Ref. 1). In equilibrium,the 226Ra/223Ra atomic ratio is about 20/1(Ref. 14), and one would thus expect a comparable ratio from uranium-mill effluents.This is seldom the case, however, becauseduring the sulfuric acid leaching process usedin most mills, radium is barely soluble butactinium-227 and thorium-227 dissolve quantitatively. These nuclides then give rise totheir daughter 223Ra in the aqueous phase(Ref. 14). The bulk of mill effluent radiumactivity turns out to be radium-223.

This brief summary is intended only topoint out the range of concentrations of radiumin typical sample media. Most of the levelsmentioned are 'natural,' in that they are notenhanced by man's use of radioactivity ...which is not to imply that man has not by hisactions increased radium activities in theenvironment. However, for the most part man'sactivities have not significantly increasedthe natural levels of radium in various media.Obvious exceptions are in the uranium mining/milling industry; and in the disposal or accidental release of radium used in industrialor medical applications.


Because radium concentrations in mostsamples are small, and because the decay alphashave such short ranges in matter (~ 5 to 10mg/cm2), direct alpha counting of environmentalsamples is seldom practical.

The techniques which have been developedfall into two separate categories, which weshall treat separately below. In the first,ahemiaaZ methods are used to separate radiumfrom the matrix in which it is found, followedby alpha counting (or sometimes alpha spectroscopy). In the second, radon gas (usuallyradon-222) is allowed to emanate from theradium-containing medium, followed by measurement of the activity of the radon or itsdaughters. Sometimes the two approaches arecombined: after chemical separation, the prepared sample may be stored for radon ingrowth,followed by radon measurements.

A. Radon Emanation Techniques

Radon emanation is by far the most widelyused method for measuring radium-226. Herewe shall give an overview of the various techniques developed for 226Ra which use radonemanation followed by measurements of 222Rn.However, for detailed discussions of 222Rnmeasurements the reader is referred to thesection "Radon-222 and Its Daughters" elsewherein this Volume.

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There are three radium -+- radon decays ofpossible interest:

224Ra -+- 22°Rn,

223Ra -+- 219Rn, and

226Ra -+- 222Rn.

However, two of the three radon isotopes,radon-2lg and radon~220, are so short-lived(4 second and 55 second half-lives, respectively) that measurements of them using emanation are unsatisfactory. Hence, the emanation technique is used exclusively withradon-222 (to determine its parent radium-226).Indeed, since the emanated gas is usuallystored for radon-220 decay, the interferencefrom the other isotopes can be made unimportant.

Direat de-emanation is an old technique.A sample is placed in a vessel filled withhelium or "old air" (e.g., air stored longenough to allow decay of natural radon) andput aside to allow 222Rn ingrowth. Forexample,'two half-lives (7.65 days) willgive 1\,75% of the maximum buildup. The simplest procedure is transfer of the ingrownradon, plus carrier gas, through a particulate filter to a Lucas chamber for alphacounting. The Lucas chamber (Ref. 15) is asmall (1\,100 to 200 cm3 volume) sphere coatedon the inside with znS(Ag) scintillator;through a flat window on one side, the scintillation light is viewed and counted by aphotomultiplier. This instrument is described in more detail in "Radon-222 and ItsDaughters. "

There are several difficulties withdirect de-emanation. Foremost is uncertaintyin knowledge of the quantitative emanationrate. Emanation from a solid medium is aprocess intimately dependent upon geometricalidiosyncrasies: for example, radon fromradium locked in crystal structures far froma surface simply does not get out with adefinite measurable efficiency. Other problems can occur because direct transfer tothe Lucas chamber (even through a high-efficiency filter, which removes radon'sdaughters) can result in errors at highhumidity, as well as in uncertainties in theelectrostatic properties within the chamber,which can seriously degrade counting efficiency.

To solve this latter set of problems,one common procedure today is to pass theradon through a pur>ifying system beforeintroduction to the Lucas chamber. Thesystem (Ref. 16, 17), described in "Radon-222and Its Daughters" and shown in Figure 1,

M.,t

A. Calibrated Vaauum TypeB. Rotameter

FIGURE 1. Sampling apparatus for ao7:leationof gaseous airborne radon (Ref. 17).

sends the radon through a Drierite trap and acooled water trap into a pre-treated activatedcharcoal radon trap at -78°C (dry ice). Thecharcoal is subsequently de-emanated at 300°Cand the radon gas transferred to a Lucaschamber with helium carrier. This transfer/purification system is quantitative, nearly100% efficient, and is almost error-free whenproperly operated.

To solve the problem of uncertainties inthe emanation of radon from the original(solid) medium, the commonest procedure todayis chemical dissolution into the liquid state.Once radium is in solution, radon de-emanationoccurs with essentially 100% efficiency.During radon ingrowth, some of the radon gascollects in the (helium) gas above the liquid.The remainder is flushed from the liquid atthe end by forcing helium through the solution.The helium-carried radon is then run directlyinto a Lucas chamber, or alternatively throughthe Drierite/water-trap/activated-charcoal/Lucas chamber system.

Special flasks have been designed forde-emanation of the radium-in-solution. Onetypical design is shown in Figure 2 (fromRef. 18): a 500 ml Pyrex flask is altered byinsertion of a 10-mm Pyrex tube (for the helium) .This flask can be easily decontaminated beforeintroduction of the liquid sample.

Rushing, Garcia, and Clark (Ref. 20)describe a system in which, after chemicaldissolution and de-emanation, the helium-radonmixture is run directly into a Lucas chamber.After transfer, 3-4 hours are aJlowed toelapse before counting, to permit 222Rn tocome to transient equilibrium with its daughters.These investigators achieved minimum detectableradium activities in the range of 0.03 pCi(in 300 ml) or about 0.10 pCi/liter. Aninterference from radon-220 may occur in this

'. .,.1 ,.J

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:J ···l , I.i'

RAD-NUCRadiumPage 7

FIGURE 2.

o

The de-emanation fZask (from Ref. 18).

in the APHA compilation (Ref. 21). Thesensitivity is comparable, and this Referencealso reports that "neither radium-224 at anactivity equal to that of the radilBll-226 nordissolved solids up to 610 mg/liter produceda detectable error in the results." ThisStandard Method satisfies nearly all requirements for sensitivity, accuracy, and versatilitywhich might be desired for environmental monitoring. Its drawback is the expense anddifficulty of operating and maintaining theequipment.

The importance of running reagent blanksthrough the entire system must be emphasized:minute radium contamination in any of thereagents can sometimes occur, and a correctionmust be applied (or the contaminant eliminated)to achieve the ultimate in sensitivity.

B. Sample Preparation for Radon Emanation

The radon emanation technique as usedtoday requires that the radium be in solution.Here we shall outline briefly some of thevarious processes developed for radilBll dissolution from the more important sample media.We shall discuss only a few methods found insome of the main radiochemical proceduresmanuals.

Of course, in many media (e.g., wateror urine) the radilBll is already in solution.However, even for some liquid media, such asraw sewage, it might be desirable to processthe radium before emanation. Also, in somesamples the dissolved radium is at too Iowaconcentration to permit measurement by emanation, so a concentration step is necessary.

method, but can be overcome by interim storageof the gas before introduction to the Lucaschamber. Even if storage is not used, a 1:1ratio of 224Ra:226Ra in the original sampleonly produces a radium-226 overestimate inthe 0.5% range, while the effect of 223Ra isan order of magnitude smaller still.

Blanchard (Ref. IS) has described acomplete system, including the Drierite/activated-charcoal purification procedure.With care to flush remanant radon from variousparts of the system, and using a 300-rnlradium-containing sample with a one-hourradon-emanation period, Blanchard measured anNBS standard (l.OOpCi of radium) to within±0.04 pCi, with an average recovery of 100± 4% for 9 trials. The limit of detection(95% confidence) is calculated to be 0.016pCi, which (in 300 rnI) corresponds to about0.050 pCi/liter.

Another emanation technique, similar toBlanchard's, is included as a Standard Method

A method applicable to water, urine, orfecal samples is described in the USAEC Healthand Safety Laboratory (HASL) Procedures Manual(Ref. 22). Radium is co-precipitated wi~barium sulfate; silica is removed with hydrofluoric acid and reprecipitation of the sulfate.The precipitate is then dissolved in alkalineEDTA (ethylenediaminetetraacetic acid), thesolution used for emanation.

A method applicable to food, milk, vegetation, soil and bone is also described inthe HASL Manual (Ref. 22). Some samplesrequire a sodium carbonate fusion, after whichthe radium carbonate is dissolved in HN0 3.

"Successive fuming nitric acid separations remove the calcium and mostother interfering ions. Traces ofsome fission products are scavengedwith yttrium hydroxide. Finally,radium is coprecipitated with bariumchromate, then dissolved in perchloricacid and water" (Ref. 22).

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The Handbook of the EPA's Las Vegaslaboratory (Ref. 23) describes a slightlydifferent method for ashed samples usingammonium chromate, and also a method for soil,sludge, and air filters in which fusion isperformed with Nicholson's flux, followed byH2S04 dissolution and a barium-carrier addition for co-precipitation of Ba-Ra phosphate.The U.S. Public Health Service's procedurescompilation (Ref. 24) describes an ammoniumdichromate dissolution method for ashedsamples.

The APHA Standard Methods (Ref. 21)describes separate methods for determiningdissolved and undissolved radium in water,using a membrane filter to separate the undissolved (suspended) matter for separatedissolution using Nicholson's flux.

5 '---'1--,-----,--,---,-----,----,4 RADIUM - 223 T ~ " . 2 days

IRADIUM -223' !

41- -3 ---- RADIUM- 224 -

0

".- 2 - -

RADIUM-226,0 2 3 4 6

TIME (hr)

653 4TIME (days)

oZ.- 2

Radiochemistry with Radium Alpha Countingc.

Here a number of the techniques will bediscussed which employ chemical separation ofradium from the medium in which it is sampled,followed by counting or spectroscopy of theradium alphas.

Ordinary chemical techniques are intrinsically incapable of differentiating amongthe various radium isotopes. Thus if simplealpha counting is used, a single measurementcan only yield total radium activity (curies).Alpha spectroscopy, on the other hand, enablesthe various alpha energies to be separatelyidentified quantitatively. Another techniquefor separating isotopes is to make activitymeasurements at several different times, sothat the build-up and decay of activitiesfrom the various radium/daughter series canbe followed. The basis for this can be seenin Figure 3 (from Ref. 25), which shows thetheoretical growth and decay of total alphaactivity (parent plus daughters) into pureradium isotopes. This time variation can beused to determine ratios of 226Ra:224Ra:223Ra.

FIGURE 3. Growth of aZpha activity into pureradium isotopes (Ref. 25).

The APHA Standard Methods (Ref. 21) describes a technique designed for screening ofdrinking water. The method is also applicableto sewage or industrial wastes, provided thatorganic matter is destroyed.

"Lead and barium carriers areadded to the sample containingalkaline citrate, then sulfuricacid is added to precipitate radium,barium and lead as sulfates. Theprecipitate is purified by washingwith nitric acid, dissolving inalkaline EDTA, and re-precipitatingas radium-barium sulfate afteradjusting the pH to 4.5. Thisslightly acidic EDTA keeps othernaturally occurring alpha emittersand lead carrier in solution."(Ref. 21)

The section "Alpha Particle Instrumentation" elsewhere in this Volume contains detailed discussions of instruments for alphacounting and spectroscopy. We will summarizehere by noting that among the common alphainstruments are internal gas proportionalcounters, solid state (surface-barrier) detectors, pulse ion chambers, and scintillators.

Because the range of alphas in matter isso small (~5 to 10 mg/cm2), one problem forthe chemist is preparation of a sample thinenough to be counted without important selfabsorption corrections. For alpha spectroscopy this is particularly difficult.

The precipitate is counted with an internalgas proportional counter, after a 3 to 18hour wait. To determine isotopic mixtures,

"additional counting at 7, 14 or 28days is suggested, depending on thenumber of isotopes in mixture. Theamounts of the various isotopes canbe determined by solving a set ofsimultaneous equations" (Ref. 21).

Average chemical recoveries are excellent(~97%) in this method, and the technique isvaluable as a screening method for routineradium-in-water analysis.

Some techniques for radiochemical determination of specific radium isotopes by measuring their daughters (lead, polonium, bismuth) will be discussed below.

The ASTM compilation (Ref. 25) describesa very similar method. The lower detectionlimit is about 1 pCi/liter. Both the APHAand the ASTM methods are based on a technique

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developed at Idaho Falls (Ref. 26) and alsodescribed by Goldin (Ref. 27).

Another chemical method is described inthe U.S.P.H.S. compilation (Ref. 24). Hereradium is coprecipitated with BaS04 fromsolution containing EDTA; the precipitateis converted to carbonate and dissolved inHN0 3• Radium daughters are extracted intothenoyltrifluoroacetone, and Ra-BaS04 isreprecipitated for counting.

A quite different method has been developed by Duquesne et al. (Ref. 28). Herethe final sulfate precipitate is suspendedin ethanol together with powdered scintillator,3nS(Ag), and this mixture is filtered anddried for counting with a photomultiplier.Sensitivity below 0.1 pCi/liter is claimed,and by studying the al~ha activity as itevolves in time the 22 Ra/ 226Ra ratio can beroughly determined.

Kelkar and Joshi (Ref. 29) describe asystem which is similar but even simpler.After a one-liter sample is filtered, HCland BaC12 are added. Radium, lead, andpolonium are co-precipitated with 36 MH2S04,and 400 mg of 3nS(Ag) are added while stirring.A Whatman 42 filter then picks up the sulfates and the 3nS(Ag) together; the filteris dried under an infrared lamp for two minutes,and counted for 30 minutes. Chemical yieldsexceed 95%, and concentrations as low as1 to 2 pCi/liter can be determined. Thismethod, though less sensitive than the moresophisticated techniques, is quick and inexpensive.

To summarize, there are a variety ofchemical methods which take advantage ofcoprecipitating radium with barium as sulfateor carbonate, to separate it from otheralpha-emitting elements (principally daughtersof the various radiums). After successivepurifications in one of several chemicalmedia, the methods either count the radiumsalt in an internal gas proportional counter,or use 3nS(Ag) and a photomultiplier tubefor scintillation counting.

In any of the methods which use alphacounting, the substitution of alpha spectroscopy can enable a direct determination ofradium isotope ratios. However, resolutionis a key consideration. Typical resolutions(± half-width) that can be obtained in variouskinds of alpha spectrometers are about ±15 keVwith surface-barrier detectors; ±20 keV withpulse ion chambers; and ±50 keV with gasproportional counters. Liquid scintillators(±150 keV) and solid scintillators (±200 keV)are poorer. Any of these systems can resolve226Ra (4.60 4.78 MeV alphas) from 223Ra, 224(5.54, 5.61, 5.71, 5.75 MeV) and Ra (5.44,5.68 MeV). However, separating these latter

two from each other is more difficult becausethe energies are so intermingled.

D. Radiochemistry with Counting of RadiumDaughters

Here we shall mention methods in whichradium daughters (other than radon gas) arecounted after radiochemical separation.

One technique, in the HASL Manual (Ref. 22)separates lead-2l2 in urine and measures thealphas from bismuth-2l2 and polonium-2l2 afterequilibration. This technique is specific forradium-224 (the precursor of 212pb). In anotherHASL technique applicable in urine or water(Ref. 22), Ra-BaS04 precipitate is stored forbuildup of Rn-222, Po-2l8, and Po-2l4, whichare measured in equilibrium using a 3nS(Ag)disk phosphor and a photomultiplier.

Petrow and Allen (Ref. 14) describe aspecific determination of radium-223. Afterradium is separated from carrier lead, it isstored for 3 hours to allow ingrowth in solution of 223Ra's daughter, lead-2ll (36.1 minutes,1.39 MeV (max) S ). The lead is then extractedfrom solution into dithizone. Interferencefrom lead-2l4 (daughter of radium-226) isminimized by boiling the solution during the3 hour period, in order to purge the 3.82-dayradon-222. The selection occurs because someof the 219Rn (4 sec) in the 223Ra + 211Pbchain decays before it too is purged in theboiling. The 6.62 MeV a from bismuth-2ll(lead-2ll's daughter) is the activity which iscounted.

A similar procedure can be used to determine radium-224. The separated radium sampleis aged for 16 - 24 hours to enable lead-2l2ingrowth from 224Ra. Lead-2l2 (10.6 hours)is separated from lead-2ll (36.1 minutes) byaging of the lead extract for 3 - 4 hoursbefore beta-counting.

Petrow and Allen (Ref. 14) also describea method for radium-228 by separation andcounting of its daughter, actinium-228. Toavoid an interference, the radium sample mustbe purified of 227Ac before 228Ac ingrowth.This is achieved by using lanthanum hold-backcarrier prior to the radium-sulfate ~recipitation. After 228Ac ingrowth from 2 8Ra, thesample is beta-counted in an internal gas proportional counter.

Sanderson (Ref. 30) has described thedetermination of 226Ra in food, soil, orbiological samples by coincidence NaI(Tl)gamma spectroscopy on the 0.6l-MeV and 1.12MeV gamma rays of bismuth- 214. Thorium- 228can also be determined by the coincident0.58-MeV and 2.6l-MeV gammas of its daughterthallium-208. Sanderson reports 226Ra measurements in the range of 0.30 pCi/g with ±10%

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errors, using 20 to 40 g samples. Minimumsensitivities in the range of 0.03 to 0.06pCi/g are reported for both 226Ra and 228Thin food, soil, and fecal ash.

To summarize, we have briefly discussedseveral chemical methods which selectivelydetermine one of the radium isotopes by thechemical or physical properties of its daughteres). These analytical methods are usefulonly in restricted circumstances, but theyare a valuable tool when detailed knowledgeof the various radium isotopic ratios isrequired.

The quick screening (gross-alpha) measurementtechniques for public health protection areadequate, and radium levels can seldom beexpected to increase suddenly to the dangerpoint where both time and accuracy would beessential. Thus the present methods, thoughtime-consuming, are probably adequate for thetask of routinely monitoring environmentalsamples for radium content.

8. ACKNOWLEDGMENT

For this section we particularly acknowledgethe generous advice and review of:

There is an obvious need for sourcesof known activity to be used for calibration purposes. To fulfill this need, theU.S. National Bureau of Standards had developed a set of standards with radium-226content ranging from 0.1 to ~100 micrograms,in flame-sealed glass ampoules (Ref. 31).These 'emanation' standards, in liquid form,are for use in calibrating an entirecounting system.

6. CALIBRATION SOURCES Donald C. Bogen,USAEC Health and Safety Laboratory, New York

Evan Campbell,Los Alamos Scientific Laboratory


Claude W. Sill,USAEC Health Services Laboratory,Idaho Falls

7. SlJMv!ARY AND CONCLUSIONS

This section has discussed the typicallevels at which radium is found in environmental samples; the radiation protectionguides; and the types of measurement techniques developed to measure radium in theenvironment. The emphasis has been placedon radium-226, although the other main isotopes (223, 224, 228) have also been discussed.

The activity levels requiring measurementare very small, and the measurement techniques are (correspondingly) sophisticated.MOst routine measurements today use eitheran emanation technique or radiochemical separation followed by alpha counting. Each ofthese types of measurement can be performedsensitively and accurately enough to determinethe radium isotopes at their naturallyoccurring activity levels in the environment.Unfortunately, each suffers from drawbacks:The radiochemical methods require exactinganalytical procedures; the emanation techniques are time-consuming and the apparatusclumsy and relatively expensive.

However, in the overall picture ofradionuclide measurement capabilities inenvironmental media, radium measurementsappear to be in a reasonably sound position.

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9. REFERENCES

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1. C.M. Lederer, J.M. Hollander, and I. Perlman, Table of Isotopes, 6th Edition, J. Wiley, NewYork (1967).

2. ICRP Publication 2, "Pennissable Dose for Internal Radiation," International Conunission onRadiological Protection, Pergamon Press, New York (1959).

3. U.S. Public Health Service, "Drinking Water Standards, Revised 1962," P.H.S. PublicationNo. 956, Washington, DC 20525 (1962).

4. S.R. Bernard and M.R. Ford, "Note on 100 and NCRP Reconunended (MPC)a for InsolubleRadium-226 Compounds," Health Physics ±' 307 (1961).

5. J.B. Hursh, "Radium Content of Public Water Supplies," Journal Am. Water Works Assn., 46,43 (1954).

6. J.A.S. Adams and W.M. Lowder (ed.), The Natural Radiation Environment, Univ. of ChicagoPress (1963).

7. L.D. Samuels, "A Study of Environmental Exposure to Radium in Drinking Water," p. 239 ofRef. 6.

8. R.C. Turner, J.M. Radley, and W.V. Mayneord, "Naturally Occurring Alpha Activity of DrinkingWaters," Nature 189, 348 (1961).

9. California Bureau ·of Radiological Health, "Estimated Daily Intake of Radionuclides inCalifornia Diets, 1968-1969," Radiol. Health Data and Reports 11,250 (1970).

10. M. DeBortoli and P. Gaglione, "Radium-226 in Environmental Materials and Foods," HealthPhysics~, 43 (1972).

11. S. Gold, H.W. Barkhau, B. Shleien, and B. Kahn, ''Measurement of Naturally OccurringRadionuclides in Air," p. 369 of Ref. 6.

12. M. Kawano and S. Nakatani, "Some Properties of Natural Radioactivity in the Atmosphere,"p. 291 of Ref. 6.

13. J.E. Pearson, "Natural Environmental Radioactivity from Radon-222," U.S. Public HealthService Pub. No. 999-RH-26 (1967).

14. H.G. Petrow and R.J. Allen, "Estimation of the Isotopic Composition of Separated RadiumSamples," Anal. Chem. 33, 1303 (1961).

15. H.F. Lucas, "Improved Low-Level Alpha Scintillation Counters for Radon," Rev. Sci. Inst.28, 680 (1957).

16. G.E. Jones and L.M. Kleppe, "A Simple and Inexpensive System for Measuring Concentrationsof Atmospheric Radon-222," Report UCRL~16952, unpublished (1966). Lawrence Berkeley Laboratory, Berkeley, CA 94720.

17. Methods of Air Sampling and Analysis, Intersociety Conunittee for a Manual of Methods forAmbient Air Sampling and Analysis. American Public Health Association, 1015 ~ 18th Street,N.W., Washington, DC 20036 (1972).

18. R.L. Blanchard, "An Emanation System for Detennining Small Quantities of Radium-226," U.S.Public Health Service Pub. No. 999~RH-9 (1964).

19. of Nuclear Materials, International

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20. D.R. Rushing, W.J. Garcia, and D.A. Clark, "The Analysis of Effluents and EnvironmentalSamples from UranilDJ1 Mills and of Biological Samples for RadilDJ1, PolonilDJ1, and UranilDJ1,"p. 187 of Ref. 19.

21. Standard Methods for the Examination of Water and Wastewater, 13th Edition, American PublicHealth Association, 1015 ~ 18th Street, N.W., Washington, DC 20036 (1971).

22. J.H. Harley (ed.) , HASL Procedures Manual, Report HASL-300, USAEC Health and Safety Laboratory,376 Hudson St., New York, NY 10014 (1972). Earlier editions of this manual were publishedas Report NYO-4700.

23. F.B. Johns, "Southwestern Radiological Health Laboratory Handbook of Radiochemical AnalyticalTechniques," Report SWRHL-ll (1970). Available from SWRHL, now EPA National EnvironmentalResearch Center, Las Vegas, NV 89114.

24. "Radioassay Procedures for Environmental Samples," PHS Publication No. 999-RH-27 (1967),U.S. Public Health Service, Bureau of Radiological Health, Rockville, MD 20852.

25. Annual Book of ASTM Standards, Part 23 (1971), American Society for Testing and Materials,1916 Race Street, Philadelphia, PA 19103. The radilDJ1 method is designated D2460-70.

26. E.R. Ebersole, A. Harbertson, J.K. Flygare, Jr., and C.W. Sill, "Determination of RadilDJ1-226in Mill Effluents," Report 100-12023, USAEC Idaho Operations Office, Idaho Falls, In 83401(1959), unpublished.

27. A.S. Goldin, "Determination of Dissolved RadilDJ1," Anal. Chem;33, 406 (1961).

28. H. Duquesne, E. Godfroi, J. Govaerts, R. Warin, and J. Michiels, "Low-Level RadilDJ1 Contentin Water Determined by Alpha Counting," Health Physics~, 927 (1963).

29. D.N. Kelkar and P.V. Joshi, "A Rapid Method for Estimating RadilDJ1 and Radon in Water," HealthPhysics 17, 253 (1969).

30. C.G. Sanderson, "Determination of RadilDJ1-226 and ThorilDJ1-228 in Food, Soil, and BiologicalAsh by Multidimensional Coincident Gamma~Ray Spectroscopy," Health Physics 16, 747 (1969).

31. U.S. National Bureau of Standards, "Catalog of Standard Reference Materials," NBS SpecialPublication 260; available from NBS, Washington, DC 20234.

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URANIUM

1. Introduction



4. Sources of Environmental Uranitnl1


RAD-NUCUranitnl1Jtme 1973Page 1

a. Gamma Spectroscopyb. Neutron-Induced Fission Methodsc. Radiochemical Analysis Followed by Alpha Cotmtingd. Fluorometric Determinationse. Other Methods


7. Acknowledgment

8. References

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1. INTRODUCTION

Uranium is widely familiar to the generalpublic. Its use in atomic (fission) bombsbrought it to the attention of the entire worldnearly three decades ago. Today it is the fuelfor the fastest growing energy source in ourmodern economy, the nuclear power reactor.

Here we shall deal with the measurementof uranium concentrations in environmentalmedia. We shall concentrate on methods fordetermining low levels of uranium in air,water, and certain other environmental media;but we shall not treat bioassay methods, whichare covered in Volume 4 ("Biomedical Instrumentation") of this Survey.

We shall first provide overviews of thephysical characteristics of the importantisotopes; of the radiation protection guidesfor uranium concentrations; and of the rangesof uranium concentrations in the naturalenvironment. We shall then discuss the variousmeasurement techniques for uranium.

Discussions which are important for amore complete picture of the measurement techniques treated in this section are found inseveral other sections of this volume. Thesesections are "Radon-222 and Its Daughters,"in which the uranium-238 decay chain and theinstrumentation for radon-222 measurementsare discussed; "Alpha Particle Instrumentation," in which instruments for detectingalphas are treated in detail; "Radium"; and"Ganuna Spectrometry".


Uranium occurs naturally in three isotopic states, uranium-234, 235, and 238.However, 234U is a daughter in the decaychain of 238U, and only the two heavier isotopes occur in natural, primordial materiaL

TABLE 1.

The 235U/238U ratio is the same essentiallyeverywhere on earth: 0•72% • The daughter234U occurs at an abundance of 0.0057%, wheni~ is in secular equilibrium with its precursor 238U.

Some physical properties of the threeisotopes are shown in Table 1 (informationfrom Ref. 1). Note that all three are alphaemitters, and that gamma rays accompany someof the alpha decays. The half-lives of thethree isotopes are all quite long. Thephysical property which has given uranium itsunique role in modern technology is fission;indeed, it is the fission of uranium-235which is used in nuclear reactors. However,for our purposes, the fission property hasvery little direct consequence as a radiological hazard. It finds occasional use indetection of uranium-235, as will be discussedbelow.


There are differences in toxicity depending upon whether uranium, when ingested,is soluble or insoluble. These differenceshave been taken into account in the establishment of radiation protection guides. Theguides for "natural uranium", which is theisotopic mixture as tabulated in Table 1,will be discussed here.

For l68-hour occupational exposures, themaximum permissible concentrations in air andwater ~WC)a and (MPC)w are given in Table 2,from ICRP Publication 2 (Ref. 2). The maximum permissible body burdens (MPBB) are alsogiven. For individuals in thegeneral public, the applicable (MPC) valuesare a factor of 10 smaller than those tabulatedin Table 2; and for exposure to a suitablylarge sample of the general public, anotherfactor of 3 smaller still.

Some Properties of the NaturaZZy Occurring Uranium Isotopes

Natural Member of Which Innnediate Main DecayIsotope Half-Life Abundance Decay Chain Daughter Products and Energies

Uranium-238 4.5 billion 99.27% U-238 Chain Thorium-234 (77%) 4.20-MeVayears (24.1 days) (23%) 4.15-MeV a + 48-keV y

0.71 billion Thorium-231 (18%) 4.37-MeV a + 234-keV yUranium-235 0.72% U-235 Chain (57%) 4.40-MeV a + 204,163-keV y's

years (25.5 hours) (25%) others

Uranium-234 247,000 years 0.0057% U-238 Chain Thorium- 230 (72%) 4.77-MeVa(80,000 years) (28%) 4.72-MeVa + 53-keV y

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TABLE 2.


Natupal Uraniwn and Radiwn-226 MPC's for Critical Organs.

168-houp/week Occupational Maximum Permissible Concentrations in Ail'

and Water, and Maximum Permissible Body Burdens (from ICRP Pub. 2, Ref. 2).

Soluble or Critical (MPC)w (MPC)a MPBBIsotope Insoluble Organ pCi/liter pCi/liter pCi

Natural Uranium soluble G.!. tract 200,000Natural Uranium soluble Kidney 0.03 5,000Natural Uranium insoluble G.!. tract 200,000Natural Uranium insoluble Lung 0.02

Radium-226 soluble Bone 100 0.01 100,000Radium-226 insoluble Lung 0.02

The comparison with radium-226 in Table 2is especially revealing. The (MPC)w is afactor of 2000 less restrictive for uraniumthan for radium, while for (MPC)a the valuesare quite comparable. Neither uranium norradium-226 is a problem in airborne suspension, except in rare circumstances involvingduststorms. Uranium is also almost never apublic health problem in drinking water,although radium occasionally is found innatural concentrations which exceed its muchsmaller (MPC)w.

4. SOURCES AND LEVELS OF ENVIRONMENTALURANIUM

Uranium occurs widely throughout theenvironment, as a trace constituent of soilsand rock. The isotopic 235U/238U ratio of0.72% is constant almost everywhere, as wehave mentioned. 238U'S presence is manifest:by the universal emanation of radon-222 fromrocks and soils (see "Radon-222 and ItsDaughters").

Uranium content of rock is usually givenin parts per million (ppm), by weight. Onemicrogram of pure 238U has an activity of 0.33pCi. Hence one ppm of pure 23 8U correspondsto 0.33 pCi/gram; however, if 234U is in equilibrium, then it adds another 0.33 pCi/g, asdoes every one of the other dozen or so membersof the 23 8U chain.

In most rocks, uranium composition is inthe range from 0.5 to 4 ppm, with thorium-232about 4 to 5 times more abundant (Ref. 4).True granite is the most uranium-rich of thecommon rocks, having typically 5 ppm of

uranium•. In uranium-mining areas, concentrations of '\,30 ppm are sometimes found (Ref. 4).Volcanic rocks have uranium at about 0.1 -0.4 ppm (Ref. 5), and Atlantic beach sandsabout 0.1 - 1.5 ppm (Ref. 6). River watersin Japan (Ref. 7) have uranium concentrationsat the level of a fraction of 1 ~g/liter ('\,0.33pCi/liter).

In material that has remained totallyundisturbed, 234U should be in equilibrium(equal activities) with its precursor, 238U.However, this is not always the case, perhapsbecause of the fact that 234U seems to existpreferentially in the hexavalent rather thanthe quadrivalent state (Ref. 8). Disequili-·brium has been reported at about the -15%level in the upper several meters of a rockygranitic outcropping (Ref. 9). Several investigators have found enhanced 234U in deepunderground waters, in some cases with morethan 7:1 for the 234U:238U activity ratio(Ref. 10). Soils, conversely, have been foundto be slightly depleted of 234U on the average.Enhancements have also been observed in normalfecal samples (Ref. 8).

Studies have been made of the uraniumcontent of typical diets. In the UnitedKingdom (Ref. 11), the concentrations in nearlyall foods were found to be in the range from0.0002 to 0.001 ppm. The intake of uraniumin food was found to be about 1.0 ~g/day,

which is similar to the value of 1.3 to 1.4~g/day found by Welford and Baird for the U.S.(Ref. 12). Domestic drinking water in theU.S. contains uranium nearly always at levels·well below 0.1 ~g/liter (Ref. 11), but somedrinking supplies have concentrations as highas 5 to 8 ~g/liter. Since the (MPC)w for

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individuals in the general public is 0.02~Ci/liter (= 60,000 ~g/liter), it can be seenthat even the highest concentrations are about4 orders of magnitude below the (MPC)w.

Air concentrations have been found to bein the range of 20 pg/liter in England; amean of 4 pg/liter over the North AtlanticOcean; and a mean of 3 pg/liter over Antarctica(Ref. 13). Again, the (MPCh for individualsin the general public is 0.002 or 0.003pCi/liter (z 6000 to 9000 ~g/liter), which is2 to 3 orders of magnitude greater than thereported concentrations.

Uranium levels are typically not muchaffected by man's activities. The most important exceptions are in and around uraniummining/milling facilities, and at nuclearfuel reprocessing plants. Even there, themain radiological and environmental effectsare seldom from uranium itself. Discussionsof the radiological problems in these areasare found in other Sections of this Volume.

From the numbers just presented, it canbe seen uranium is not often a radiologicallyimportant nuclide. This does not imply thaturanium measurements are unimportant: Insituations such as around uranium mills, environmental measurements are required tomonitor any possible long-term build-up trendsin the environment. Also, the radiologicalsignificance of radium, radon, and the radondaughters is widespread.


Among the environmental media requiringmeasurement of uranium activity are rocks,silt and soil; natural and waste waters; food;and air (air filters). Because the uraniumconcentration in most samples is small, andbecause the decay alphas have such short rangesin matter (~5 to 10 mg/cm2), direct alphacounting of environmental samples is seldompractical.

The techniques which have been developedfall into several categories. We shall discuss them separately below. These categoriesare:

a. gamma spectroscopyb. neutron-induced fission methodsc. radiochemical analysis followed by

alpha countingd. fluorometric determinationse. other methods

The number and variety of uranium-determination methods is so large that to surveythem all would be impossible. For example,the index to Nuclear Science Abstracts for the

year 1971 lists about 200 entries under thesubject heading "Uranium Determination••."We shall not attempt here to do more than mentionthose techniques which are found in theprocedures manuals of some of the largeranalytical laboratories; or which are worthyof mention as representative of a large classof techniques.

A. Gamma Spectroscopy

Table 1 indicates that several of theuranium alpha decays are accompanied by garrnnaemissions. Also, when 238U or 235U is inequilibrium with its daughters in the longdecay chains, several gamma-emitting nuclidescan be detected. The unique signature of achain can make possible increased sensitivityin the presence of higher backgrounds, comparedto the measurement of only a single gamma.

We shall not discuss here the detailedconsiderations involved in gamma spectroscopicmeasurements: These are treated in "GammaSpectrometry" elsewhere in this Volume. Itsuffices to mention here that the two maintechniques are NaI(Tl) scintillation systemsand Ge(Li) solid state detector systems, thelatter with significantly better energy solution but poorer detection efficiency than theformer.

Of course, the farther down the chain anuclide is, the greater the chance for disequilibrium with the parent; this is especiallytrue for measurements of radon-222 daughtersas indicators of uranium-238, since radon'semanation can destroy secular equilibrium.

The most prominent gamma in the 23 8Uchain is the 1. 76-MeV gamma from 214Bi. Astudy of the 238U chain reveals that among thenuclides prior to radium-226, there are nogamma rays which combine a significant branchingratio (~ 1%) and an energy above 100 keV. Only214Pb and 214Bi have gammas with energies above300 keV. The 226Ra gamma (4%) has an energyof 185.7 keV. The 2"3'5U chain has several moreprominent gamma rays, but their relative intensity is limited by the 235U/238U isotopic ratioof 0.72%. Indeed, 235U itself has a l85-keVgamma (54%), but it is very difficult to resolvein the presence of the 226Ra gamma at 185.7 keV.

When NaI(Tl) is used, the gamma emissionmost corrnnonly analyzed is the 1.76-MeV y ofbismuth-2l4, since it stands out at high energyabove nearly all of the other naturally-occurring garrnna lines. Similarly, the 2.62-MeV yfrom thallium-208 is commonly used as a signature for the thorium-232 chain. Adams andFryer (Ref. 14) describe a portable NaI(Tl)spectrometer used for field surveys of naturalU, Th, and 40K content in soils and rocks,using which accuracies in the few percent

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range are obtained for uraniwn concentrationsin the range of several ppm.

Wollenberg and Smi~h (Ref. 15) have alsoapplied NaI(Tl) techniques to geologicalassays. They point out the possible difficulties with disequilibriwn in the 238Useries:

"Uraniwn can be leached fromits host material, there are longhalf-lived decay members, and thegaseous member can be lost to theair -- three conditions which maylead to lack of equilibriwn. Mostof the uraniwn-series y rays comefrom daughters of radiwn; therefore,some • • • assays may really reflectonly radiwn content. This situa-tion would seem most likely tooccur with soil samples." (Ref. 15)

Smith has indicated (Ref. 16) that dis-equilibrium is seldom a serious problem insolid rocky material, since neither leachingnor radon emanation is significant.

Of course, Ge(Li) detectors, with theirvastly superior resolution, are able to distinguish gamma lines which could never beresolved by a NaI(Tl) system. Figures 1 and2 (from Ref. 18) show a comparison of NaI(Tl)and Ge(Li) spectra measured on the same sample.Note that the Ge(Li) spectrwn, of which onlythe region below 1 MeV is shown, reveals finestructure not even suggested in the NaI(Tl)spectrwn. Nevertheless, NaI(Tl) instrwnentshave competed reasonably with Ge(Li) systemsfor field uraniwn assay, especially at thelowest levels of sensitivity. There areseveral reasons for this, among which are thatthe 214Bi line stands out prominently evenwith NaI(Tl); that NaI(Tl) has greater detection efficiency; and that the lines which mightbe studied with Ge(Li) are mainly at low energy,where backgrounds are higher, especially inthe field.

Both NaI(Tl) and Ge(Li) systems have sensitivities in the range of a fraction of oneppm, more than adequate for most uraniwn assaystudies. An intrinsic advantage of gammaspectroscopic methods is the ability to measurelarge (many-gram) samples non-destructively.Adams and Gasparini (Ref. 19) have written agood overview of the entire field of gammaspectral studies of rocks.

B. Neutron-Induced Fission Methods

The fact that ,235U fissions in the presence of thermal neutrons is e~loited innuclear reactor technology. (2 8U requiresfast neutrons.) This is also the basis for

several measurement techniques for extremelylow concentrations of 235U in various media.

When a heavy nuclide (2 ~ 90) undergoesfission, a small fraction of the fissionproducts are neutron-rich and subsequentlydecay by neutron emission. This "delayedneutron emission" is unique to the fissionprocess: There is hardly any other processwhich produces neutron emission. The onlyknown exceptions are 4.2-second nitrogen-17and 0.17-second lithiwn-9, neither of whichcauses a background in uraniwn measurements ofthis kind. Measurement of the delayed neutronscan be used as an indicator of the concentration of uranium-23s (or other fissionableradionuclides).

Arniel (Ref. 20), irradiating samples ina slow-neutron flux of 4 x 1012 n/cm2sec,reports sensitivities to less than 0.1 ~g ofuraniwn. With a (maximwn) sample size of .200 g, this sensitivity approaches 1 ppb.For thoriwn this method is about one order-ofmagnitude less sensitive. The system, whileexpensive, suffers from practically no interferences. Hamil ton has reported an even lowerdetection limit, about 0.01 ~g U with ±10%precision (Ref. 13).

Hamilton has also reported a technique ofmuch greater sensitivity (Ref. 13): Uraniumladen dust (on an air filter or in solution)is placed on a polycarbonate detector which isirradiated for 1 hour in a neutron flux of5 x 1011 n/cm2sec. After 24-hour storage toallow for the decay of short-lived activity,the polycarbonate is etched in 6 N NaOH andexamined under a conventional X450 microscope.The total nwnber of tracks is simply counted,each track being the record of a fission eventin the detector. Sensitivities in the rangeof 1 x 10- 14 g U are reported. Hamilton showsthat this method is practically unique for235U, except in circwnstances where very largeamounts of plutonium-239 are present.

C. Radiochemical Analysis Followed by AlphaCounting

Chemical analysis techniques are a mainstay for the determination of extremely lowlevels of activity. The chemical separationof uraniwn produces enrichment with respect tothe background matrix in which the sample isfound, and makes possible alpha-counting oralpha-spectroscopic determinations of verygreat sensitivity.

The difficulty with alpha-counting andspectroscopy is that the short range of alphas(5-10 mg/cm2) requires the preparation of anearly 'weightless' sample. This in turnleads to the main disadvantages with these

.. )'--/

i .~

\.,-/

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IN SITU NaI (TI)SPECTRUM20 MINUTE COUNTING TIME

o 20 40 60 80 100 120CHANNEL

140 160 180

FIGURE 1. In situ speatrum, northeastern U.S. Zoaation, taken in 1971 with 10 am x 10 amNaI(TZ) arystaZ, 20-minute aounting time (from Ref. 18).

IN SITU Ge (L1) SPECTRUM40 MINUTE COUNTING TIME

1000

Ac-Z28

A908 966/ I

900BOO

Nb-952,-95 BI-214Bi-ZIZ 766-68724-Z7/

/ Ac-Z28

A195 831

I /

700600

TI-208 BI-214TI-208 583 609

511 \ /I

500CHANNEL

Sb-125

i28

400300

Pb-214Ac-228 /"--.27,0-8/95 }52

H31?I 365

300 I /Pb-212 ~

328 338\,../

Ac-228

200

Pb-214Ra·224

. Pb-212

Ra-226 23/-241

186I

100

100

1000

..J...zZ<l:I:U

a:...Q.

UllZ::>ou

FIGURE 2. In situ speatrum, taken with that in Fig. 1 with 60-am 3 Ge(Li) deteator, 40-minuteaounting time. Photon energies in keV (from Ref. 18).

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techniques, which are the difficulty and inconvenience of the analytical procedures, andthe liability for error. (See "Alpha ParticleInstrumentation" elsewhere in this Volume.)

EZeatpodeposition is one commonly-usedtechnique for preparing a uranium sample forcounting. The discussion here will be limitedto only a few of the very many electrodeposition techniques in the literature. The U.S.Public Health Service procedures manual(Ref. 21) describes a procedure in whichuranium nitrate, dissolved in dilute ammoniumoxalate, is electrodeposited on a nickelplated copper disk. Iron, commonly presentwith uranium, does not interfere. AnotherU.S.P.H.S. technique, by Levine and Lamanna(Ref. 22), is based on solvent extraction ofuranium with ethyl acetate, using aluminumnitrate as a salting agent. This procedureis simple, but less sensitive than the other.Talvitie (Ref. 23) describes still anothermethod for electrodeposition of Pu, Th, Uand Am as hydrous idns. Separation of thevarious activities is perfonned using analpha spectrometer, with a claimed detectionlimit of about 0.02 pCi of activity.

Another class of chemical techniques isaoppeaipitation. This type of technique,widely used for radium determination (see"Radium"), can be used for simultaneous determinations of several alpha activities whenfollowed by alpha spectroscopy. For example,Lieberman and Moghissi (Ref. 24) describe atechnique suitable for environmental samplesincluding ashed food, vegetation, and soil.Uranium coprecipitation with lanthanum fluoride is followed by alpha spectroscopy usinga gas-flow proportional counter. Samplescontaining a few Y. 10- 15 Ci/liter of uraniumand thorium have been analyzed quantitatively(Ref. 24). This type of procedure is simplerand less expensive than electrodeposition, butmore liable to error either from interferencesor from inability to obtain complete dissolution of the ashed sample prior to the preci~i

tation. An oxidation-reduction procedure canhelp to avoid this problem, but is tricky.

Sill (Ref. 25) describes a coprecipitation method using barium sulfate, in whichall of the elements from radium through cali~

fornium, exaept Ul'aniwn. are precipitated byBaS04' Uranium can be included if it is allreduced to the quadrivalent state. Alphaspectroscopy can be used to distinguish amongthe several alpha emitters, or alternatively,"because of their markedly different oxidationpotentials, uranium and the first four transuranium elements can be separated efficientlyfrom each other by proper choice of oxidant"(Ref. 25). Sill's separated fraction caneither be alpha-counted directly, or electrodeposited for precise alpha spectroscopy.

D. Fluorometric Determinations

The use of fZuopometpy is one of theoldest techniques for uranium determination.Here only a few of the methods in common usewill be described.

The Manual of the EPA's Las Vegas laboratory (Ref. 26) describes a fluorometry technique in which, after total dissolution, auranium/uranium-fluoride complex (which fluoresces under ultraviolet light) is fonned. Theprincipal interference is from iron, whichunfortunately accompanies uranium in manysample media and which must be eliminated bycareful chemical analysis.

The U.S.A.E.C. Health and Safety Laboratory (HASL) Procedures Manual (Ref. 27)describes a method in which uranium is fusedwith sodium fluoride for UV fluorescence.This method, developed for urinalysis, isequally applicable to most other dissolvedmedia. A sample-preparation method for bone,soil, food, and tissue is also described inthe HASL Manual. Uranium is leached from adry-ashed residue and isolated by anionexchange chromatography plus mercury cathodeelectrolysis before fusion with sodium fluoride.

Rushing, Garcia, and Clark (Ref. 28)present a fluorometric method similar tothat in the HASL Manual. Their descriptiongoes into detail about some of the importantproblems with the technique. For example,

" .•• in order to obtain themaximum fluorescence. . • , itis necessary that the uraniumexist in the hexavalent conditionin the final melt. While thefusion process will oxidize theuranium, it is best that reducingsubstances, such as carbon, beoxidized before the fusion step isundertaken" (Ref. 28).

One drawback with fluorometric methodsis the possibility that a standard radiochemical laboratory might not have the UVfluorometric equipment available. Anotherproblem, already mentioned, is interferencefrom iron, especially in iron-rich media.Centanni, Ross and DeSesa (Ref. 29) have discussed some of the detailed considerationsrequired for accurate fluorometric measurements, and Akaishi and Yabe (Ref. 30) havepointed out some of the cautionary pointswith the technique.

E. Other Methods

There are numerous other methods foruranium determination, which shall not be

,I

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discussed here at all. Among these are polarography (Ref. 31), spectrophotometry (Ref. 32),coulometry (Ref. 33, 34), and x-ray fluorescence(Ref. 35). The recent book by Jeffrey (Ref. 36)is a general reference on rock chemical.analysis.The reader is referred to the appropriatereferences for details.


This section has briefly discussed thetypical levels at which uraniwn is found inthe environmental media; the radiation protection guides; and some of the types of techniques which have been developed to measureuraniwn in the environment.

Although the activity levels requiringmeasurement are small, the radiological hazardfrom uranium in the environment is also neatlyalways small.

The techniques for uraniwn measurementare varied, and among them they offer sufficient sensitivity to perform nearly all ofthe required measurements. Each of the classesof methods has significant disadvantages, andthe choice of method should undoubtedly bebased as much on the skill of the analyst andthe facilities available to him as on theintrinsic merit of the particular method.However, some general comments can be made insummary:

a. The gamma spectroscopy methods, whilerelying on equilibriwn in the longdecay chains, are otherwise perhapsthe easiest and cleanest of thetechniques.

b. The neutron-induced-fission techniques offer high selectivity andsensitivity, but are unfortunatelynot very accessable to many analyticallaboratories.

c. Alpha spectrometry after radiochemicalseparation allows the simultaneousdetermination of several alpha-emitting activities, which is advantageousin many measurement situations. However, care must be taken to obtainknown chemical yields in the presenceof possible unknown interferences.

d. Several chemical-analysis techniques(fluorometry, cou1ometry, spectrophotometry) probably require moreanalytical care than the other techniques, but otherwise seem to beacceptable. The existence of multivalent uraniwn compounds in a complexmediwn such as soil requires specialconsideration.

In conclusion, the analysis of uraniwn inenvironmental samples can now be performedwith any of several methods, and is probablynot one of the problems which requires extensive new research and development in thenext few years. This is especially truegiven the small radiological importance ofuranium and also the several other more pressing problems in the area of environmentalradiation measurements.

7. ACKNOWLEDGMENT

For this section we particularly acknowledge the generous advice and review of:



David L. Stevenson,EPA National Environmental Research Center,Las Vegas

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8. REFERENCES


1. C.M. Lederer, J.M. Hollander, and I. Perlman, Table of Isotopes, 6th Edition, J. Wiley, NewYork (1967).

2. ICRP Publication 2, "Permissable Dose for Internal Radiation," International Connnission onRadiological Protection, Pergamon Press, New York (1959).

3. J.A.S. Adams and W.M. Lowder (editors), The Natural Radiation Environment, University ofChicago Press, Chicago (1964).

4. G. Phair and D. Gottfried, "The Colorado Front Range, Colorado, U.S.A., as a Uranium andThorium Province," p. 7 of Ref. 3.

5. K.S. Heier and J.L. Carter, "Uranium, Thorium, and Potassium Contents in Basic Rocks andTheir Bearing on the Nature of the Upper Mantle," p. 63 of Ref. 3.

6. A. Mahdavi, "The Thorium, Uranium, and Potassium Contents of Atlantic and Gulf Coast BeachSands," p. 87 of Ref. 3.

7. Y. Miyake, Y. Sugimura, and H. Tsubota, "Content of Uranium, Radium, and Thorium in RiverWaters in Japan," p. 219 of Ref. 3.

8. C.W. Sill, USAEC Health Services Laboratory, National Reactor Testing Station, Idaho Falls,ID 83401 (private connnunication).

9. K.A. Richardson, "Thorium, Uranium, and Potassium in the Conway Granite, New Hampshire,U.S.A. ,If p. 39 of Ref. 3.

10. A.I. Spiridonov, A.N. Su~tankhodzhaev, N.A. Surganova, and V.G. Tyminskii, "Some Results ofStudy of the Isotopes of Uranium 234U:238U in Ground Waters of the Tashkent Artesian Basin,"Uzb. Geol. Zh. !' 82 (1969).

n. E.I. Hamilton, "The Concentration of Uranium in Man and His Diet," Health Physics E, 149(1972) .

12. G.A. Welford and R. Baird, "Uranium Levels in Human Diet and Biological Materials," HealthPhysics 13, 1321 (1967).

13. E. I. Hamil ton, "The Concentration of Uranium in Air From Contrasted Natural Environments,"Health Physics 19, 511 (1970).

14. J.A.S. Adams and G.E. Fryer, "Portable y-Ray Spectrometer for Field Determination of Thorium,Uranium, and Potassium," p. 577 of Ref. 3.

15. H.A. Wollenberg and A.R. Smith, "Studies in Terrestrial y Radiation," p. S13 of Ref. 3.

16. A.R. Smith, Lawrence Berkeley Laboratory (private connnunication).

17. International Atomic_Energy Agency, Rapid Methods for Measuring Radioactivity in the Environment, IABA, Vienna (1971).

18. H.L. Beck, W.M. Lowder, and J.E. McLaughlin, "In Situ External Environmental Gannna-RayMeasurements Utilizing Ge(Li) and NaI(Tl) Spectrometry and Pressurized Ionization Chambers,"p. 499 of Ref. 17.

19. J.A.S. Adams and P. Gasparini, Gannna-Ray Spectrometry of Rocks, Elsevier Publishing Co.,Amsterdam (1970).

20. S. Amiel, "Analytical Applications of Delayed Neutron Emission in Fissionable Elements,"Anal. Chern. 34, 1683 (1962).

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21. PHS Publication No. 999-RH-27, "Radioassay Procedures for Environmental Samples," U.S.Public Health Service, Bureau of Radiological Health, Rockville, MD 20852 (1967).

22. H. Levine and A. Lamanna, "Radiochemical Determination of Uranium in Environmental Media byElectrodeposition," Pub. 999-RH-ll, U.S. Public Health Service, Washington, DC 20201 (1965).

23. N.A. Talvitie, ''Electrodeposition of Actinides for Alpha Spectrometric Determination," Anal.Chern. 44, 280 (1972).

24. R. Lieberman and A.A. Moghissi, "Coprecipitation Technique for Alpha Spectroscopic Determination of Uranium, Thorium, and Plutonium," Health Physics 15,359 (1968).

25. C.W. Sill, "Separation and Radiochemical Determination of Uranium and the Transuranium ElementsUsing Barium Sulfate," Health Physics Q, 89 (1969).

26. F.B. Johns, "Southwestern Radiological Health Laboratory Handb~ok of Radiochemical AnalyticalTechniques," Report SWRHL-ll (1970). Available from SWRHL, now EPA National EnvironmentalResearch Center, Las Vegas, NV 89114.

27. J.H. Harley (editor), HASL Procedures Manual, Report HASL-300, U.S.A.E.C. Health and SafetyLaboratory, 376 Hudson Street, New York, NY 10014 (1972). Earlier editions of this Manualwere published as Report NYO-4700.

28. D.R. Rushing, W.J. Garcia, and D.A. Clark, "The Analysis of Effluents and Environmental Samplesfrom Uranium Mills and of Biological Samples for Radium, Polonium, and Uranium," p. 187, Vol. IIof Radiolo ical Health and Safet in Minin and Millin of Nuclear Materials, InternationalAtoIll1c Energy gency, Vl.enna 1964.

29. F.C. Centanni, A.M. Ross and M.A. DeSesa, "Fluorometric Determination of Uranium," Anal. Chern.~, 1651 (1956).

30. J. Akaishi and A. Yabe, "Some Cautionary Problems of Fluorometric Determination of Uranium,"Report JAERI-13622, Japan Atomic Energy Research Institute, Tokai (1969).

31. H.E. Zittel and L.B. Dunlap, "Polarographic Determination of Uranium (IV) in Sodium Tripolyphosphate Supporting Electrolyte," Anal. Chern. 34, 1757 (1962).

32. K. Motojima, H. Yoshida, andK. I zawa , "Spectrophotometric Determination of Small Amounts ofUranium with 8-Quinolinol," Anal. Chern. 32, 1083 (1960).

33. C.M. Boyd and O. Menis, "Coulometric Determination of Uranium (IV) by Oxidation at ControlledPotentials," Anal. Chern. 33, 1016 (1961).

34. W.D. Shults and P.F. Thomason, "Controlled-Potential Coulometric Determination of Copper andUranium," Anal. Chern. 31, 492 (1959).

35. R.D. Giauque, F.S. Goulding, J.M. Jaklevic, and R.H. Pehl, "Trace Element Determination withSemiconductor Detector X-Ray Spectrometers," Anal. Chern. 45, 671 (1973).

36. P.G. Jeffrey, Chemical Methods of Rock Analysis, Pergamon Press, London (1971).

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PIDTONIUM

1. Introduction



4. Sources of Environmental Plutonitun

S. Measurement Considerations

a. Radiochemical Analysis Followed byCounting or Spectroscopy

b. Air Filter Collection Followed by Countingc. Gamma and X-Ray Spectroscopyd. Other Methods


7. Acknowledgment

8. References

RAD-NUCPlutonitunJune 1973Page 1

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RAD-NUCPlutoniumPage 3

1.· INTRODUCTION

Plutonium is by far the most important ofthe transuranic elements (elements heavier thanuranium). Its use in atomic (fission) weaponshas made it a strategically important material,and it is the cornerstone in the fast-breederreactor system which is now under development.Plutonium is also highly toxic, a fact recognized very early in its history. This toxicitymakes measurements of plutonium in environmental media very important.

We shall not dwell on those many facetsof plutonium which are not directly relevantto our immediate task. Rather, we shall dealwith the measurement of plutonium concentrations in environmental media. We shall concentrate on methods for determining low levels ofplutonium in air, water, soil, and certainother environmental media; but bioassay methodswill not be discussed; these are covered inVolume 4 ("Biomedical Instrumentation") ofthe Survey.

We will first provide overviews.of thephysical characteristics used in the detectionof the important isotopes; of the radiationprotection guides for plutonium concentrations;and of the sources of and typical ranges ofplutonium concentrations in the natural environment. We shall then discuss the variousmeasurement techniques for plutonium. Thisdiscussion will concentrate on the variousbroad categories of instruments and techniquesfor plutonium measurements, their sensitivities,areas of applicability, and limitations.

Discussions which are important for amore complete picture of the measurement techniques treated in this section are found inseveral other sections of this volume; thesesections are "Alpha Particle Instrumentation,"in which instruments for detecting alphas aretreated in detail; "Gannna Spectrometry";"Radium"; and ''Uranium''.

Four recent publications provide detailedinformation ona number of subjects concerningplutonium. The first is the "Proceedings of theRocky Flats Symposium on Safety in PlutoniumHandling Facilities, 1971" (Ref. 1). The secondis Radiobiology of Plutonium, a 1972 compendiumedited by Stover and Jee (Ref. 2). The third isa 1971 "Symposium on the Biological Implicationsof the Transuranium Elements", containing muchvaluable information (Ref. 3). Finally, a 1971Environmental Plutonium Symposium discussespathways to man and measurement methods (Ref. 4).


The isotopic states which concern us areplutonium-238 through -242. Some physical properties of these isotopes are shown in Table 1(information from Ref. 5). The isotoRe americium-24l, the immediate daughter of 41Pu, isalso listed in Table 1 because its propertiesare used in some plutonium measurements.

The half-lives of the three most importantisotopes are all relatively long: 23BPu (86years); 239Pu (24,400 years); and 24°Pu (6580years). The alpha energies are grouped suchthat present alpha sRectrometry systems cannotseparate 239Pu from 4°Pu, but can cleanlyresolve all of the other plutonium isotopes.

TABLE 1.

Some Properties of the Important PZutoniwn Isotopes, and of Americiwn-241(from Ref. 5)

Half-Life Main Decay ProductsIsotope (years) and Energies (MeV)

Plutonium-236 2.85 a (5.72, 5.77)

Plutonium-237 0.12 electron capture

Plutonium-238 86. a (5.46, 5.50)

Plutonium-239 24,400. a (5.16, 5.15, 5.11)x-rays (0.017 , 3.8%)

Plutonium-240 6,580. a (5.12, 5.17)

Plutonium-24l 13.2 S- (0.021 maximum)Plutonium-242 379,000. a (4.86, 4.90)

Americium-24l 433. a (5.44, 5.49)y-ray (0.060, 36%)x-ray (0.014, 0.017, others)

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The fact that 2.39Pu fissions under the

impact of slow neutrons is the physical property which has made plutoniwn so important.However, the fission property has for our purposes very little direct consequence, eitheras a hazard or as a means for measuring plutonium in the environment.

3. RADIATION PR01ECTION GUIDES

Plutonium is relatively hazardous, compared to many of its neighboring elements inthe periodic table. The various hazards havebeen taken into account in the establishmentof the radiation protection guides. The toxicity depends on the mediwn, of course: airborne soluble plutoniwn transfers across thelung mucosa and ultimately is largely depositedin bone, where its tumor-forming hazard isgreater than that of radiwn-226. As solubleplutoniwn in water, it is absorbed by the GItract and again deposits preferentially inbone. When plutoniwn is insoluble, the criticalorgans are the sites of direct exposure, thelungs and GI tract. Recently, concern has alsobeen expressed that the limiting effect forinsoluble airborne plutoniwn might be the doseto the pulmonary lymph nodes (Ref. 6), autopsies having shown significant plutonium burdensthere (Ref. 7).

TABLE 2.

For l68-hour occupational exposures, themaximwn permissible concentrations in air andwater, (MPC)a and (MPC)w, are given in Table 2,from ICRP Publication 2 (Ref. 8). The maximumpermissible body burdens (MPBB) are also given.Note that for individuals in the general public, the applicable MPC values are a factor of10 smaller than those tabulated in Table 2;and for exposure to a suitably large sampleof the general public, another factor of 3smaller still (Ref. 9).

Note the comparisons in Table 2 withradiwn-226 and natural uraniwn. In insolubleform Pu, U, and Ra have comparable MPC values.However, the MPC for soluble plutonium in airis a factor of 15 more restrictive than thatfor 2. 2. 6Ra. In water, on the other hand, theMPC is 500 times less restrictive than forradiwn. These differences are direct manifestations of the biomedical-pathway toxicities.

4. SOURCES AND LEVELS OF ENVIRONlffiNTALPLUTONIUM

Plutoniwn is produced by certain nuclearreactions, mainly in nuclear reactors. Itsisotopic composition is variable, dependingupon the method and conditions of production.The most important production mechanism creates

168-HouP/Week OaaupationaZ Maximum PepmissibZe Conaentpations in Aip

and Watep, and Maximum PepmissibZe Body Bupdens

(fpom ICRP Pub. 2, Ref. 8)

Soluble or Critical lMPC)w (MPC) a MPBBIsotope Insoluble Organ !lCi/liter pCi/liter (!lCi)

Plutoniwn(238, 239,240, 242) Soluble Bone 0.05 0.0006 0.04

Radiwn (226) Soluble Bone 0.0001 0.01 0.10

Plutoniwn(238, 239,240, 242) Insoluble Lung --- 0.01 ---

Radiwn (226) Insoluble Lung --- 0.02 ---Natural

Uraniwn Insoluble Lung --- 0.02 ---

Plutoniwn(238, 239,240, 242) Insoluble GI tract 0.30 --- ---

NaturalUraniwn Insoluble GI tract 0.20 --- ---

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239Pu by neutron capture on 23 8U to form 23 9U,which a-decays (23.5 minutes) to 239Np, whichin turn a-decays (2.3 days) to 239Pu. Plutonium240, the next mos t abundant isotope after 23 9Puis formed by a second neutron capture on one of'the 239 isotopes. In plutonium being producedfor weapons, the 2'+ °Pu concentration mus t bekept below the few-percent level; otherwise,too many spontaneous neutrons from 2'+°Pu willeither set off a premature chain reaction ordecrease the energy yield of the explosion (Ref.10). In plutonium for commercial power-reactoruse, on the other hand, 2'+°Pu is expected to bepresent at about 30% abundance (Ref. 10). AtRocky Flats (where weapons-graqe plutonium isproduced), a typical mixture contains the following isotopic fractions (Ref. 11):

238Pu 0.04 ± 0.01%239Pu 93.34 ± 0.5 %2'+°Pu 6.00 ± 0.5 %2'+lPu <\'0.58 %2'+2Pu '\,0.04 %

The concentration of americium-24l isdependent upon the time for ingrowth from itsparent, 2'+lPu (13.2 years).

Nearly all of the plutonium in the worldtoday exists at only a few types of locations:in nuclear weapons; in the nuclear-reactorfuel cycle; and in stockpiles. The most probable sources of plutonium in the enviromnentare equally easy to classify: nuclear weaponsalready exploded; wastes or leaks from thereactor fuel cycle, most likely around plutonium production facilities or fuel reprocessingplants; and occasional unique events, such asthe burnup of a plutonium-fuelled power cellin a satellite accident (Ref. 12, 13).

Studies of plutonium in surface air havebeen carried out for several years by theU.S.A.E.C.'s Health and Safety Laboratory. Arecent compilation (Ref. 14) indicates that in1969, typical 239Pu world-wide concentrationswere in the range from 1 to 50 X 10- 8 pCi/literof air. The higher number is a factor of 40lower than the (MPC)a value for exposure tolarge general populations; the smaller numberis 2000 times lower. In 1966, the average 238Pu/239Pu ratio in air was 0.04 (Ref. 15), and themonthly surface deposition of 239Pu from precipitation ranged from about 0.5 to about 1.0pCi/m2 (Ref. 15). Studies of plutonium in surface soil in the Livermore Valley of Californiahave found 239Pu surface levels of 200 to 2000pCi/m2 (Ref. 16). Children's diets in 1966showed 23 9Pu concentrations of about 0.002 to0.006 pCi/kg (Ref. 15). This is more than 5orders of magnitude smaller than the generalpopulation (MPC)w.

These world-wide distributions are mostlydue to fallout from nuclear weapons tests, plusthe aforementioned satellite accident, whichdeposited 17,000 curies of 238Pu in the stratosphere over the Indian Ocean in 1964 (Ref. 12,13). As the numbers reveal, the world -widelevels are not now significant fractions ofthe MPC limits for general-population exposure;and since fallout hopefully will not increasedramatically, the levels should also not increasedramatically. The main radiological hazard isthus more likely local than worldwide in scope.Local concentrations can range up to valuesmuch higher than the worldwide averages justmentioned. One example is at the Nevada TestSite, where many locations have 23 9Pu in soilsat levels of 100's to 1000's of pCi/gram overseveral acres (Ref. 17). Another example isnear the Rocky Flats plutonium production facility, where plutonium air concentrations haveoccasionally reached as much as 30% of thesoluble (MPC)a for individuals in the generalpublic (Ref. 18).

One important point which must be bornein mind is that plutonium deposited on soilis not a significant direct public health hazard. One prime pathway to man is resuspensionfrom the ground into the air, which can resultin widespread distribution of an originallywell-localized source, and which in turn maylead to more widespread public health exposures.This possibility has motivated a program withinthe U.S.A.E.C. to study the problems of resuspension (Ref. 19).


Among the enviromnental media requiringmeasurement of plutonium activity are siltand soil; natural and waste waters; food; andair. The techniques which have been developedfall into several categories. We shall discussthem separately below. These categories are:

a. Radiochemical Analysis Followed byCounting or Spectroscopy

b. Air Filter Collection Followed byCounting

c. Gamma and X-Ray Spectroscopyd. Other Methods

Because plutonium concentrations in most samples are small, and because the decay alphashave such short ranges in matter ('\,5 to 10mg/cm2), direct alpha counting of enviromnentalsamples is seldom practical.

A. Radiochemical Analysis Followed byCounting or Spectroscopy

A wide variety of techniques for radiochemical analysis have been developed for

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plutonium detenuinations in various media.Chemical separation produces enrichment withrespect to the matrix in which the plutoniumis found, and makes possible alpha counting oralpha spectroscopy with increased sensitivities.

The main difficulty in alpha detection isthe extremely short range of the alphas (5 to 10:mg/cm2), which requires preparation of a nearly'weightless' sample. An important chemicalanalysis difficulty is that the weight of the~lutonium in samples may be minute: 1 pCi of- 39Pu weighs only 16 pg.

Perhaps the greatest problem with plutonium radiochemistry is the insolubility of onecommon chemical fonu, plutonium oxide. Wequote from Healy (Ref. 20):

"Plutonium oxide fired at hightemperatures is a notoriously insolubleceramic. If present at larger particlesizes it is exceedingly difficult toput into form for a chemical separation.However, very small particles such asare found in natural fallout or othermaterials, including oxide which hasbeen fonned at a lower temperature,are much more soluble and can beleached from the sample with relativelymild treatment."

The media requiring chemical analysisare usually of three general classes: watersamples, air-filter samples, and soil samples.Other possible media are food, urine, andbiological and fecal samples. The general problem of low solubility may be present in nearlyall of these media.

Chemical methods can be divided into twogeneral classes: those that bring the entiresample into solution, and those that use aleaching technique to extract the plutoniumfrom the matrix. The leach methods are generally easier, but are also more liable to error.•• hence, periodic total-dissolution and crosscomparisons are often used to check the yieldsfrom the leach methods.

In all-of the radiochemical analyses, theuse of either plutonium-236 or plutonium-242as a tracer for chemical yield is common.Both 236Pu (5.72, 5.77 MeV) and 242Pu (4.86,4.90 MeV) decay by emitting alphas of suffidently different energy that they can beresolved from 239Pu by using alpha spectros-copy. The tracer should be added at theearliest possible stage, of course. Unfortunately, the tracer technique cannot adequatelycorrect for insolubility losses, one of thecommonest problems, since soluble tracer doesnot exchange with insoluble 239PU02 unlessthere is complete dissolution to soluble ionicforms (Ref. 22). Another consideration, empha-

sized by Sill (Ref. 22), is that at least asmuch tracer should be used as unknown Pu beingdetenuined. Otherwise, the statistical uncertainty in the determination is limited by the236Pu statistics. Lindeken (Ref. 23) has pointedout that one advantage of 242Pu is that it hasa lower energy so that there are no contributions to the 2hPu energy region from possibleenergy degradation of the tracer's alpha.

Sill (Ref. 24) describes a method forsoils, in which "the sample is decomposed completely by a combination of potassium fluorideand silicon tetrafluoride. The cake is dissolvedin dilute HCl and all alpha emitters are precipitated with barium sulfate." Sill claimsrecoveries of 94 ±3% for all elements fromthorium through plutonium, and describes amethod for separating and electrodepositingthree fractions for separate alpha spectroscopy: _ (Am, em, and Cf), (Th), and cPa, U, Np,and Pu). Sill also claims that the method isreliable "in soils in which complete dissolution of both the siliceous matrix and the mostinsoluble fonus of plutonium oxide that can beproduced can be guaranteed routinely" (Ref. 24).

Another total-dissolution method has beendescribed by Talvitie (Ref. 25), in which adsorption from a hydrochloric acid medium isfollowed by a-nitriC acid wash for removal Ofiron. Anion exchange is then used for plutoniumseparation, followed by electrodeposition.

The leaching methods, which are commonlyused for SOlI analysis, are claimed to beeasier and faster than the total dissolutionmethods. One method prominently mentioned inthe literature is that of the U.S.A.E.C.'sHealth and Safety Laboratory (Ref. 26, 27).This method is designed for 100-gram soilsamples. Soil is leached with a mixture ofHN0 3 and Hel. Leached Pu is converted to Pu (IV)with sodium nitrite and absorbed from 8N HN0 3

for electroplating.

This method presents problems in thepresence of highly insoluble Pu02, and theU.S.A.E.C. 's Nevada Applied Ecology Group(Ref. 28) has adopted instead a Los Alamosmodified technique, the so-called 'modifiedHASL-lASL" method (Ref. 29), which uses HFas well as HCl in the leach process to improvethe yield. Mter leaching, an anion exchangeresin column is used for Pu separation followedby electroplating. The electroplating step maypresent an important roadblock, because itlimits the number of samples which can be runin parallel unless many electroplating cellsare available. Also, even this improved methodmay suffer from yield difficulties when verylarge samples are analyzed.

Levine and Lamanna (Ref. 30) describemetfiods in which "solubilized plutonium as

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.. )

,/


the chloride is reduced to the tri-valentstate, coprecipitated with lanthanum carrieras the fluoride, dissolved in acid aluminumnitrate and extracted with thenoyltrifluoracetone (TTA) for separation and removal ofimpurities and carrier. The plutonium is thenback-extracted with strong acid, oxidized andelectrodeposited on stainless steel for counting." Bowen et a1. (Ref. 31) report a similarprocedure.

B. Air Filter Collection Followed byCountmg

The most common method for monitoring plutonium in air is by the collection of activityon an air filter, followed by direct countingof the collected activity. Unless an identification of the isotopes is possible from separate knowledge, the type of measurement isreally a "gross-alpha" determination. The MPCafor soluble plutoni1,lJ1l is 6 x 10- 5 pCi/liter forindividuals in the general public. The countingrate from such an activity level is extremelylow: 6 x 10- 5 pCi gives about 1.3 disintegrations per week. Measurement of such activitiesrequires the sampling of many liters of air.There are two different classes of measurements: those which measure continuously whilethe activity accumulates, and those whichmeasure the activity after a fixed collectionperiod. The latter are the more sensitive, andthe more frequently used.

In all of the methods to be describedbelow for air filters, no distinction is madebetween soluble and insoluble plutonium. Thusthe measurement must be considered as, andcompared to, the soluble MPCa (which is themore restrictive).

One common collection system has beenused by Lawrence Livermore Laboratory personnel at the Nevada Test Site (Ref. 32). An airsampler with a pumping speed of 10 ft3/min(1 ft 3/min = 28.4 liters/min) pulls air througha convoluted fiberglass filter. Particles assmall as 0.025 ~ are collected at >99% efficiency, and 90% efficiency can be obtainedeven at sizes as large as 50 ~.

At Rocky Flats, sampling at about 1 ft 3 /

min is used (Ref. 33). Us ing a rate of 10ft3/min, and with an air concentration equal to one·general-public-MPCa.' it would take about 1 hourof sampling to collect 1 pCi (= 2.2 dpm) on thefilter.

The most important background is usuallyfrom the daughters of radon-222. The MPCafor radon daughters is about 5 orders of magnitude higher than for plutonium, and radonoccurs naturally in typical surface air atconcentrations of 0.1 to 1 pCi/liter. In somelocations (for example, in some areas in the

Rocky Mountains) even higher ambient concentrations are found. Radon-220 (thoron gas) and itsdaughters can also provide a similar type of background, but usually at much smaller concentrations. Since the filters are efficient collectorsof radon and thoron daughters, any measurementsystem.for plutonium must be able to discriminateagainst the much larger radon background.

There are four techniques which are commonly used to achieve the necessary discrimination:

i. alpha spectroscopyii. alpha-to-beta ratio method

iii. radiochemical analysisiv. 4-day hold-up to allow for decay of

the short-lived activities

i. Alpha Spectroscopy

Measurement of the alpha energy spectrumfrom the activity deposited on an air filter isvery effective for discrimination against radonand thoron daughters. The alpha energies fromdecay of radon-222, polonium-2l8, and polonium214 are 5.49, 6.00, and 7.69 MeV, respectively.The highest-energy alpha from an important plutonium isotope is 23 8Pu 's 5.50 MeV,which wouldbe difficult to resolve in the presence of largeamounts of 222Rn. 239Pu emits in the 5.15 MeVregion, which is easily resolvable. The daughtersof radon-220 (thoron) all emit alphas withenergies above 6 MeV, and are therefore quiteeasily rejected. At Rocky Flats, Griep (Ref. 33)has performed alpha spectroscopy using a largesurface-barrier detector, with an area of 350mm2 • An earlier device using a different solidstate detector was developed at Lawrence Livermore Laboratory (Ref. 34). These types ofinstruments are capable of discriminating between23 9Pu and the higher -energy backgrounds withplutonium activity of less than 1 pCi/m3 ofair, sampled for 8 hours. Both of the instruments just mentioned were designed primarilyfor occupational rather than environmentalmonitoring. The Livermore instrument caneasily detect one 40-hr-occupational MPCa withan 8-hr sampling time at 1 ft3/min: thisconcentration yields about 15 counts/min in thedetector, which has a 25% overall efficiency.

Figure 1 (from Ref. 34) shows the spectrumfrom the Livermore detector when radon daughtersare present together with plutonium. The sampling parameters are 1 ft 3/min for 8 hr. Theradon daughters reach equilibrium very quickly:Ra A (218

pO) has a 3.05 min half-life. Thereforetheir activity levels on the filter are smallerby orders of magnitude than their total collectedactivities.

Use of an internal gas proportional counterfor alpha spectrometry yields resolutions nearlyas good as with a solid-state detector, with theadded ability to count larger filter areas.

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RAD-NUCPlutonitnnPage 8

FIGURE 1. Radiwn A (PoZoniwn-21B) interferenae in pZutoniwn detection(from Ref. 34).

have very different energy spectra. This can· bedone by using an appropriate absorbing foil toproperly compensate for the different energies.

Typical instrtnnents of this design havebeen described by Spaa (Ref. 36), Rankin (Ref.37), and Gupton (Ref. 38), among others. Spaa' sdesign aims for continuous alarm capability.A filter paper is moved semi-continuously(stepwise) across a 70 liter/min pump. Continuous counting is performed during activity accumulation, using a ZnS(Ag)/photomultiplier alphadetector and an end-window G-M beta counter •Every 12 hours the filter is automatically movedstepwise, and is available for more precisemeasurements if required. In the presence ofradon daughters at 10 pCi/liter of air, plutoniumat 0.002 pCi/liter was the approximate limit ofdetection after about 1 hr of sampling.

Rankin (Ref. 37), using solid scintillationdetectors for both CI. and S counting, detectedplutonitnn at a lower limit of about 800 pCi inthe presence of 0.1 pCi/liter of radon-222.With a 24-hr sampling time at 10 ft 3/min, thisalso corresponds to a plutonium concentrationof 0.002 pCi/liter of air. Gupton's instrtnnent(Ref. 38) is very similar, but also providesanother G-M detector which is not exposed tothe filter, for external gamma compensation.

Tanaka et al. (Ref. 35) describe an improvement of the technique in which an alpha s~ec

trometer is used to further select the 23 Pusignal. A CsI(Tl) scintillation spectrometer isused, and alpha particles are selected frombeta particles by pulse-shape discrimination.In 24 hours, it can detect plutonitnn levels aslow as 10-'+ pCi/liter in the presepce of radonat about 0.1 pCi/liter.

iii. Radiochemical Analysis of Air Filters

A method for radiochemical analysis ofair filters has been adopted as a tentativemethod by the Intersociety Conunittee (Ref. 39).This method is similar to one found in the HASLManual (Ref. 27). ''The plutonium is ..• isolatedby co-precipitation with ceritnn and yttriumfluorides ••• further purified by a double anionexchange coltnnn technique •.• finally electrodeposited onto a platintnn disk" (Ref. 39). Thefirst ion-exchange process is from HCl, thesecond from an HN03 meditnn. A solid-state spectrometer determines the Pu isotopes; 236Pu isused as a tracer. This method claims a practicaldetection limit of about 8 x 10- 8 pCi/liter with±10% error (1 0'), when air is collected at about700 liters/min for about one week. For smallervoltnnes of air, sensitivity is reduced proportionately. The difficulty with this method is,as might be expected, that dissolution of hightemperature-fired Pu02 is not necessarily complete, leading to possible underestimation of

Ra C'7.68 Mev

5

CROSS HATCHEDAREA REPRESENTSRa A ACTIVITYAPPEARING' ASPLUTONIUM

o ._.L..-l._..L--l--"~~I--I.._..I.-.l.l.--I( 2 3 4 5 6 7 8 9

ENERGY (Mev)

25

Ie 20z::;)

oo 15w>~ 10....Jwa:

ii. Alpha-to-Beta Ratio Method

In this method, plutonitnn is distinguished from the radon and thoron daughtersusing the fact that the important naturalalpha emitters have a special si~ature usingCI. S coincidence counting. Ra C ( l'+Bii emits aS- almost immediately befOre Ra C~ (2 '+Po) emitsits alpha ••. the same is true of Th C (212Bi)and Th:C~ (212PO). This is because the halflives of Ra CoO and Th C~ are so smrt: 164 llsecand 0.30 llsec, respectively. Thus CI. S coincidences can be used to measure the level of theradon/thoron-daughter activities. One difficultywith this technique is that it relies on comparing two (sometimes) large) ntnnbers toobtain the (sometimes small) plutonitnn activity.

When a filter is measured by two different(alpha- and beta-sensitive) detectors, lack of100% detection efficiencies means that therecannot generally be a one-to-one subtractionof the CI. S coincidences. Rather, the CI. S coincidence rate must be electronically weightedbefore subtraction. Given a fixed resolvingtime and fixed detection efficiencies it istheoretically possible to cancel out both theradon and the thoron chains exactly, asidefrom statistical fluctuations (Ref. 35), provided the deposited daughters are in equilibrium. To do this subtraction properly, verycareful calibrations are required. Becausethoron daughters have a longer average halflife, they will dominate for collection periods in the lO-hr range, while for a l-hr collection period radon daughters usually dominate (Ref. 36). However, for a given detector,one must take care to equalize the detectionefficiencies for the Th C and Ra C betas, which

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the concentration. However, since the MPCa forsoluble plutonium is smaller oy a factor of 16than that for insoluble plutonium, the proOlemof insolubility losses is usually not seriousfor air-filter measurements.

production facilities, and so on. Here the goalis· to locate and quantify the surface activity(llCi/m2), rapidly and conveniently. The presumption is made that detailed soil samplingmust be relied on for more refined measurements.

Channel No. (opproK I-keV/channel)

FIGURE 2. Speat1'a fo1' 241Am and baakgY'oundas measu1'ed with a 5-in.-diam by1/15-in. -thiak NaI (TZJ saintiZZation deteato1'. SoU:t'ae was 10.7-11Ci241Am, and soU:t'ae-to-deteato1' distanae was 30.5 am. Optimum disa1'iminato1' settings fo1' 17-keV bandand 50 keV a1'e shown (f1'om Ref. 42J.

One instrument type often used for thistask is a thin NaI (T1) crystal of large area,coupled to a photomultiplier tube. The archetype specifically for plutonium contaminationis the FIDLER detector developed at LawrenceLivermore Laboratory (Ref. 42). It has a 5"diameter 1/16" thick NaI (T1) crystal, and isdesigned to be carried by hand over the terrainat about one foot above ground level. Thebattery-operated electronic circuitry separatesand counts two 'windows' in the energy spectrum,one around 17 keY and the other around 60 keV.These are shown, along with a spectrum from apure 241Am source, in Fig. 2 (from Ref. 42).An instrument of this type must be calibratedagainst several variables. First, its responseis sensitive to activity distributed over awide area. Further, the thickness and composition of any overburden material, as well as theplutonium isotopic distribution, will affectthe interpretation of the results.

Assuming a 12-second time-constant for thecount:"rate meter and that the instrument is beingcarried slow1r over the terrain, the minimumdetectable 24 Am point source is about 9400 pCi,

104 103

•.5 ~~ 11 •• ~~

~ cc 8~ u8 II 103 "c"

,c •~ u• "'2u

1~e..

Vi .><

J

C. Ganuna and X-Ray Spectroscopy

Gamma and x-ray spectroscopy is an important plutonium measurement technique in somesituations, and may be thought of as complementary to the radiochemical-analysis methods,since the applications of this type of spectroscopy are usually for measurements of anentirely different class. The reader is referred to a separate section of this Volume fora more detailed treatment of this class ofinstruments (See "Gamma Spectrometry").

The field survey of large surface areasfor possible plutonium contamination is onesuch application: for example, much efforthas gone into large-area surveys around theNevada Test Site. Another application is forplutonium assay in media which are not accessible to radiochemical analysis: examples arelarge soil samples, bioassay of plutonium inlungs, or plutonium detection in a solid-wastecontainer.

The method usually relies on detectingdecay photons from one of two important phenomena. The first phenomenon is the 59.6-keVgamma ray emission which accompanies 36% ofthe decays of 241Ain, the daughter of 241Pu.241Pu is seldom the main plutonium isotopepresent, and even if it were it is not usuallythe main hazard, being a beta-emitter. Therefore, this method is useful for gross-plutoniummeasurement only if one knows both the 'age'of the plutonium (to determine ingrowth of241Am) and the original isotopic ratios.

The second phenomenon is the 17-keV x-raiemission saoup which accompanies abOut 3. 8% 0the 23 9PU ecays. Actually, the emissions areL x-rays from the daughter 23 5U. The energiesof the three most prominent lines are 13.6,17.2, and 20.2 keY with relative intensities100:120:25 (Ref. 40). Americium-241 decaysare also accompanied by x-rays in the same17-keV region (actually the L x-rays of itsdaughter, 237Np). The energies of the americium lines (Ref. 41) are 14.0, 17.8, 20.8,and 26.3 keY, with relative intensities (photons/alpha) of 12%, 13%, 3%, and 2.5%. (Noteagain for comparison the 36% 59.6-keV americiumganuna.)

The task of field-surveying for plutoniumcontamination on the ground has received considerable attention, although it actually hasa rather narrow range of application such asat the Nevada Test Site, near plutonium

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The backgrounds are higher using NaI(Tl)for lung-counting applications, but the detection efficiencies are also higher. It seemsthat the proportional counters as described inRef. 40 are more difficult to construct andoperate. Overall, the two types of instrumentshave comparable sensitivities.

A solid-state Ge(Li) assay technique hasbeen developed by Tyree and Bistline (Ref. 45).This system can resolve the 51.6-keV ganma rayfrom239

Pu in the presence of the 59.6-keV241Am gamma. The 51.6-keV 239Pu gamma occurswith an 8.4% branching ratio. Using this systemand a l-hr counting time, minimum detection(3 cr) of a few thousand pCi of 23 9Pu was possible. These authors also report detection ofthe l4.0-keV 241Am line with 3.7% resolution(full width, half maximum) using a Si (Li) detector, compared to 14% using a proportionalcounter (Ref. 46). This is shown in Fig. 4.

and the minimum detectable area-distributedsource is 19,200 pCi/m2

, both at 3.3 cr above anatural background of about 200 counts/min.

An instrument similar to the FIDLER butusing a 5"-diameter, 1/8"-thick CaF 2 (Eu) scintillator has been developed by Nuclear Chicago(Ref. 43). The claimed advantages of CaP 2 (Eu)are that it does not require the careful hermetical sealing characteristic of NaI(Tl); andthat there is better optical coupling to atapered conical light pipe, which partiallycompensates for the lower light output (40-50%of that for NaI (Tl) ).

A similar instrument, but using an 8"diameter, O.Z"-thick NaI(Tl) crystal, has beenused for assay of the lung burden of exposedindividuals (Ref. 44). For a 100-minute counting time, the minimum detectable activity (3 cr)was found to be 6200 pCi of 23 9Pu. Countingefficiency must be determined with a phantom,because absorption and scattering of the lowenergy photons is very large. The counting efficiency (counts per 23 9Pu disintegration) wasmeasured to be only about 4 x 10- 4

, the majorityof the x-rays being absorbed or scattered. Theprincipal irreduceable background is fromde~aded gammas due to the decays of 40K and1 3 Cs in a normal body.

Use of twin large-area gas proportionalcounters is also conmon for Pu lung assays.With this technique Tomitani and Tanaka (Ref.40) report 12.6% resolution (full width halfmaximum) on the 13.6 keY line; this is shownin Figure 3. With an outer ring of wires foranti-coincidence shielding to provide a vetowhenever cosmic ray particles traverse thechamber, the minimum detectable activity (3 cr)is 6000 pCi of 239Pu, using a 100-minutecounting time.

o'"l-e.>

'"I-'"o., I--4--\-+IIz'">'"

2 I. PROPORTIONA~ DETECTOR

2. SI~ICON ~ITHIUM ORIFTEO

FIGURE 3. X-~ay speot~um of 239Pu • 13.6, 17.2and 20.2 keV X-~ays a~e La, LS and Ly oha~

aote~istic X-~ays of 235U, ~espeotively.

X-~ays of ene~gy about 5.96 keV a~e the fluo~esoent X-~ay of the stainless steelhousing (f~om Ref, 40).

80 100 .120

Channel number

"........'-:... . .

o"",,",",t''''' _." ..' .......,..,;."..

600

500

400f-,

300

200 ~

100

20 40

5.96 keY

I

60

13.6 keY

I.....

'12.6%'-,.'

0° ..'...

'40

17.2 keY

I

"

160

20.2 keY

I

...:..:: .........f80 200

CHANNE~ NUMBER

FIGURE 4. P1'opo~tional and Si(Li) deteoto~

speot~a from ame~ioium-241. The three peaksshown have ene~gies of 14.0, 17.8, and 20.8keV, and a~e aotually L x-rays from neptunium-237 (from Ref. 46).

Tyree and Bistline (Ref. 46) report use ofthe relative attenuation of the various x-raylines to give a measurement of the depth of acontaminating source, such as plutonium in awound. Several-nun depths are measured to fractions of one nun. The relative attenuations ofthe 13 and 20 keY uranium L x-ray lines withthickness are shown in Figure 5 (Ref. 47).

4 ,l

l ~)

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..c'" 4ou

~:;:

I'--'---l._-'-_-L._-'--_L--.-Jo 400 800 1200

Tissue Equivalent Absorber Thickness Img/cm2)

FIGURE 5. Plot of the ratio of the 13 and20 keV uranium Lx-ray intensitiesas a function of increasing absorber thickness (from Ref. 47).

Another detector type useful for this classof measurement consists of a thin NaI (Tl) crystal optically coupled to a much thicker CsI(Tl)crystal behind. This system is usually calleda 'phoswich' detector. The low-energy x-raysa-:e totally absorbed by the NaI (Tl), whileh1gher~energy photons (or charged particles)count 1n the CsI (Tl). Both scintillators arev~ewed by the same photomultiplier tube (seeF1g. 6), and the signals can be differentiatedby pulse-shape analysis since NaI(Tl) has a250-nsec optical decay time compared to 1100nsec for CsI (Tl). This type of instrument cansuppress high-energy backgrounds by factors of3 to 10.

KOranda et al.(Ref. 48) have developed asemi-portable Ge(Li) spectrometry system forfield surveys of soil. The system rides in avan, and is designed to combine the betterr~solution of a solid-state detector systemW1th the needs for mobile surveying in thefield. The system seems more valuable for thehigher energy gammas from fission products andnatural emitters, rather than for the low-energyplutonium photons.

D. Other Methods

several other types of determinations,which do not ultimately rely on alpha or ganmacounting for the plutonium measurement, havebeen developed. We shall not discuss these hereat all, but shall merely refer the reader tosome references for details. Generally thesemethods are not sufficiently sensitive forenvironmental measurements. (i) Controlledpotential coulometry (Ref. 49) is useful whenPu concentrations are high (~O.l ~Ci/liter) andaccuracy is required. (ii) Constant-currentpotentiometric titration (Ref. 50) is alsocorrrnonly used at these concentrations. (iii)Amperometric techniques (Ref. 51) can be usedf<;>r accurate work with very large (::10 ~Cilllter concentrations. (ivl spectrophotometry(Ref. 52) is applicable above about 0.1 ~Ci/

~iter. ~v~ Square wave polarography (Ref. 53)1S sens1t1ve down to ~O.l ~Ci/liter.

6. SUMMARY AND CONCWSION

In this section we have given overviewsof the typical levels at which plutonium isfound in environmental media; of the radiation

rMAGNETIC SHIELD

\ LOW BACKGROUND~~~~=:::~ VOLTAGE DIVIDER BASE·

LOW BACKGROUND ------,HOUSING [STAINLESS STEEL]

[csr (TL)]SCINTILLATOR

[NAT (TL)]

SCINTILLATOR A

LOW NOiSEPHOTOMULTIPLIER

LOW BACKGROUNDOPTICAL WINDOW

FIGURE 6. Harshaw phoswich detector: matched window type for x-ray andlow energy gamma detection.

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. Page 12

protection guides; and of some of the types ofmeasurement techniques which have been developed for plutonium measurements in the environment.

The material is very dangerous and theradiation protection guides are necessarilyvery restrictive. Fortunately, important plutonium contamination in the environment is notwidespread. A small level of world-wide plutonium from fallout is supplemented by higherconcentrations in only a few well-localizedareas, where plutonium contamination may bean important radiobiological factor.

The ideal instrument or technique forplutonium determinations should be capable ofmeasuring concentrations down to fractions of~1PC levels in the appropriate medium. Thereare two main classes of measurements, fieldand laboratory measurements. Of the types ofmeasurements considered here, only two are ofthe field-type: surveys of plutonium deposition on the ground, and air concentrationmeasurements. Even the latter are often performed by laboratory analysis of an air filterafter field sampling.

We shall summarize the situation in eachof the various measurement areas separately:

A. \1easurements of Plutonium on and in Soil

There are two basically different techniques: first, field surveying; and second,radiochemical analysis followed by alphacounting or spectroscopy. The field-surveymeasurements demand less accuracy, and are nowperformed by carrying counting instrumentsabove the terrain. The archetype of this classis the FIDLER, which has a thin, large-areaNaI(TI) scintillation detector. Instruments ofthis type seem adequate for most rough fieldsurvey measurements. Radiochemical analysistechniques are intrinsically much more sensitive and accurate, but suffer from their owritypes of difficulties. The most precise andsurefire techniques involve total dissolution... but these are laborious, time-consuming,and expensive. There are a number of leachingmethods which are intrinsically faster andcheaper. Many of these present difficultiesin the presence of insoluble matter, such ashigh-temperature-fired PU02. There certainlyseems to be need for further improvement inthe analytical chemical methods. In particular,the development of a faster and less expensiveleach method possessing a high yield would bedesirable.

B. Measurements of Plutonium in Air

Measurements of plutonium in air arenearly always made by collecting particulate

activity on an air filter for cOWlting. Themain background is usually due to daughters ofradon, which must be discriminated against.One method is to perform radiochemical analysis,followed by spectroscopy. This technique,while intrinsically sensitive and accurate, isexpensive, time-consuming, and liable to radiochemical-yield errors. The two most commonmethods which use direct counting of the filterare the alpha beta coincidence technique andalpha spectrometry. Both are sensitive and precise; perhaps a spectrometers are to be preferred for the most precise and background-free requirements, but the a S coincidencetechnique is advantageous since it has beenadapted for continuous measurements duringsample collection. Hbwever, because of thevery low MPCa value, none of the methods presently available combines rapid or continuousdetection with sensitivity well below MPCa •

C. Measurements in Soil or Bioassay UsingGamma Spectroscopy

Bioassays of lung or other body burdens,and also measurements in bulky samples suchas large amounts of soil, can be performedwith gamma spectrometers, typically usingeither NaI(Tl) or Ge(Li) detectors. Thesemethods all suffer from one intrinsic problem:it is necessary to trade off resolution forsensitivity. High resolution Ge(Li) detectorscapable of high detection efficiency are available only at great expense; on the other hand,the much larger NaI (TI) crystals suffer frompoor resolution which is a handicap especiallyin the presence of higher-energy gamma fluxes.This problem is inherent to the method.

D. Measurements in Other Media

Measurements in media such as urine,plants, food, and tissue are typically maderadiochemically. There is also a wide varietyof chemical methods (coulometry, spectrophotometry, polarography, etc.), which are mainlyuseful at relatively high concentrations. Theradiochemical analyses of various media usuallyconsist of initial sample-treatment stepsdesigned to bring all of the plutonium intosolution, followed by analysis identical tothat used in the analysis of soil or water.

It seems probable that more sensitive andfaster methods for measurements of plutoniumin man can be developed, using extensions ofpresently-available technology. The motivationfor this is probably not great at the presenttime since its application would be limitedlargely to measurements in a few occupationalexposure situations.

i ~ ";,.) !.<,' ~J '"-~) J f) ,

• I xJ

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E. Conc1us ions

At present, measurements at levels significantly below MPC values for individuals inthe general public are ~ossib1e in each of themain measurement situahons Where public healthis involved or where pathways in the environment require study. In particular, radiochemical analyses in the laboratory followed byalpha spectroscopy are quite sensitive andsuffer from few interferences. Unfortunately,the best of these methods are expensive andtime-consuming.

Given the probable growth in use of plutonium as the nuclear power industry expandsand as the breeder-reactor program grows, itseems important that methods be developedwhich enable sensitive but inexpensive determinations of plutonium in air and water effluents, as well as in soil and biomedical media.

7. ACKNOWLEDGMENf

For this section we gratefully acknowl-edge the generous advice and review of:

Donald C. Bogen,USAEC Health and Safety Laboratory,New York

Eric B. Fowler,Los Alamos Scientific Laboratory

Paul H. Gudiksen,Lawrence Livermore Laboratory

Carl L. Lindeken,Lawrence Livermore Laboratory


David S. ~ers,Lawrence Llvermore Laboratory


David L. Stevenson,EPA National Environmental Research Center,Las Vegas

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8. REFERENCES


1. "Proceedings of the Rocky Flats Symposium on Safety in Plutonium Handling Facilities, April13-16, 1971," Report CONF-71040l, available from Dow Chemical Co., Rocky Flats Division,Golden, CO 80401.

2. B.J. Stover and W.S.S. Jee, Radiobiology of Plutonium, J.W. Press, University of Utah, SaltLake City, Utah (1972).

3. "The Biological Implications of the Transuranium Elements, Proceedings of the Eleventh HanfordBiology Symposium, 27 September 1971," published in Health Physics 22, 533-955 (1972).

4. E.B. Fowler, R.W. Henderson, and M.F. Milligan, "Proceedings of Environmental Plutonium Symposium," Report LASL-4756, Los Alamos Scientific Laboratory, Los Alamos, I'M 87544 (1971).

5. C.M. Lederer, J.M. Hollander, and r. Perlman, Table of Isotopes, 6th Edition, J. Wiley, NewYork (1967).

6. D.S. Myers, "A Plea for Consistent Lung Burden Criteria for Insoluble Alpha Emitting Isotopes,"Health Physics 22, 905 (1972).

7. E.E. Campbell, M.F. Milligan, W.D. Moss, H.F. Schulte, and J.F. McInroy, "Plutonium in AutopsyTissue," Report IA-4875, Los Alamos Scientific Laboratory, Los Alamos, I'M 87544 (1973).

8. ICRP Publication 2, International Commission on Radiological Protection, Pergamon Press, NewYork (1959).

9. ICRP Publication 6, International Commission on Radiological Protection, Pergamon Press, NewYork (1964).

10. V. Gilinsky, "Bombs and Electricity," Environment 14, 11 (Sept. 1972).

11. R.G. DelPizzo, J.B. Owen, and E.A. Putzier, "Rapid Estimation of Americium-24l Content in Plutonium," Health Physics 18, 725 (1970).

12. H.L. Volchok, "Fallout of Pu-238 from the SNAP-9A Burnup," Report HASL-227, USAEC Health andSafety Laboratory, 376 Hudson Street, New York, NY 10014 (1970).

13. P.W. Krey, "Atmospheric Burnup of a Plutonium-238 Generator," Science 158, 769 (1967).

14. "Radionuclides in Surface Air," Report HASL-242, Appendix C, USAEC Health and Safety Laboratory,376 Hudson Street, New York, 10014 (1972).

15. P.J. Magno, P.E. Kauffman, and B. Shleien, "Plutonium in Environmental and Biological Media,"Health Physics 13, 1325 (1967).

16. P.H. Gudiksen, C.L. Lindeken, C. Gatrousis, and L.R. Anspaugh, "Environmental Levels of Radioactivity in the Vicinity of Lawrence Livermore Laboratory, 1971," Report UCRL-S1242, LawrenceLivermore Laboratory, Livermore, CA 94550 (1972).

17. 1.L. Eberhardt and R.O. Gilbert, "Statistical Analysis of Soil Plutonium Studies, Nevada TestSite," Report BNWL-B-2l7, Battelle Pacific Northwest Laboratories, Richland, WA 99352 (1972).

18. H.L. Volchok and R.H. Knuth, ''The Respirable Fraction of Plutonium at Rocky Flats," HealthPhysics ~, 395 (1972).

19. G. Holladay, S. Bishop, P. Phelps, and L.R. Anspaugh, "A System for the Measurement of Deposition and Resuspension of Radioactive Particulate Released from Plowshare Cratering Events,"IEEE Trans. Nucl. Science NS-17 (1), 151 (1970).

20. J .W. Healy, "Problems of Plutonium Measurement in the Environment," IEEE Trans. Nuc1. ScienceNS-19 (1), 219 (1972).

21. International Atomic Energy Agency, Rapid Methods for Measuring Radioactivity in the Environment,IABA, Vienna (1971).

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

CjC, .? "oJ


22. C.W. Sill, comments on p. 199 of Ref. 21.

23. C.L. Lindeken, Lawrence Livermore Laboratory, private communication.

24. C.W. Sill, "Separation and Radiochemical Determination of Uranium and the Transuranium ElementsUsing Barium Sulfate," Health Physics 17, 89 (1969).

25. N.A. Talvitie, "Radiochemical Determination of Plutonium in Environmental and Biological Samplesby Ion Exchange," Anal. Chem. 43, 1827 (1971).

26. N.Y. Chu, ''Plutonium Determination in Soil by Leaching and Ion-Exchange Separation," Anal. Chern.43, 449 (1971).

27. J.H. Harley, ed., HASL Procedures Manual, Report HASL-300, USAEC Health and Safety Laboratory,376 Hudson Street, New York, NY 10014 (1972). Earlier editions of this manual were publishedas ~eport NYO-4700.

28. USAEC Nevada Applied Ecology Group, USAEC Nevada Operations Office, Las Vegas, NV 89114.Attention: Paul Dunaway.

29. E.B. Fowler, Los Alamos Scientific Laboratory, private conununication.

30. H. Levine and A. Lamanna, "Radiochemical Determination of Plutonium-239 in Low-level Environmental Samples by Electrodeposition," Health Physics 11, 117 (1965).

31. V.T. Bowen, K.M. Wong, and V.E. Noshkin, "Plutonium-239 in and over the Atlantic Ocean,"J. Marine Research 29, 1 (1971).

32. L.R. Anspaugh, et aI., "Biomedical Division Preliminary Report for Project Schooner," ReportUCRL-507l8, Lawrence Livermore Laboratory, Livermore, CA 94550 (1969).

33. V.R. Griep, "Air Monitor for Plutonium-239 Utilizing Semiconductor Detector," Report RFP-l046,Dow Chemical Company, Rocky Flats Division, Golden, CO 80401 (1968).

34. W.A. Phillips and C.L. Lindeken, "Plutonium Alpha Air Monitor Using a Solid State Detector,"Health Physics ~' 299 (1963).

35. E. Tanaka, S. lwadate, and H. Miwa, "A High-Sensitivity Continuous Plutonium Air Monitor,"Health Physics 14, 473 (1968).

36. J.H. Spaa, "A Rapid Indicating Instrument for the Stepwise Measurement of Airdust Radioactivity,"Health Physics !' 25 (1960).

37. M.O. Rankin, "The Use of Coincidence Counting Teclmiques for Analyzing Low Level Plutonium Contamination on Filters," Nucl. Inst. and Methods 24, 221 (1963).

38. E.D. Gupton, "Alpha Air Monitor for Plutonium-239," Report ORNL-1M-2011, Oak Ridge NationalLaboratorY, Oak Ridge, TN 37830 (1967).

39. Intersociety Committee for a Manual of Methods for Ambient Air Sampling and Analysis, Methodsof Air samtlin~ and Analysis, American Public Health Association, lOIS-18th Street N.W., Washington,DC 20036 197 ).

40. T. Tomitani and E. Tanaka, "Large Area Proportional Counter for Assessment of Plutonium LungBurden," Health Physics 18, 195 (1970).

41. L.B. Magnusson, "Intensities of X-rays and Gamma Rays in 21+1Am Alpha Decay," Phys. Rev. 107,

161 (1957). ---

42. J.F. Tinney, J.J. Koch, and C.T. Schmidt, "Plutonium SUrvey with an X-ray Sensitive Detector,"~~~ Report UCRL-7l362, Lawrence Livermore Laboratory, Livermore, CA 94550 (1969).

43. B.S. Burton and M.N. Anastasi, "Development and Construction of an Instrument to Detect fissionable Materials," Report AFWL-TR-71-l45, Air Force Weapons Laboratory, m (1972). Report availablefrom Nuclear Chicago Corp., 9101 Research Blvd., Austin, TX 78766.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCPlutoniwnPage 16

44. T. Ishihara, T. Iinwna, E. Tanaka, and S. Yashiro, "Plutoniwn Lung Monitor Using a Thin NaI(Tl)Crystal of Large Area," Health Physics 17, 669 (1969).

45. W.H. Tyree and R.W. Bistline, "Plutoniwn-239 Detection in Vivo with a Geraniwn-Lithiwn Array,"Report RFP-1488, Dow Chemical Company, Rocky Flats Division, Golden, CO 80401 (1970).

46. R.W. Bistline and W.H. Tyree, I'A Comparison of Low-Energy Photon Detection for Plutoniwn andAmericiwn Wound Counting," Report RFP-l068, Dow Chemical Company, Rocky Flats Division, Golden,CO 80401 (1967).

47. J .A. Cooper, N.A. Wogman, H.E. Palmer, and R. W. Perkins, "The Application of Solid State Detection to Environmental and Biological Problems," Health Physics 15, 419 (1968).

48. J.J. Koranda, P.L. Phelps, L.R. Anspaugh, and G. fblladay, "Sampling and Analytical Systems forMeasuring Environmental Radioactivity," p. 587 of Ref. 2l.

49. J.R. Stokely and W.D. Shults, "Controlled-Potential Coulometric Determination of Plutoniwn inthe Presence of Iron," Anal. Chern. 43, 603 (1971).

50. C.E. Pietri and A.W. Wenzel, "Improved Method for the Constant-Current Potentiometric Determination of Plutoniwn," Talanta 14, 215 (1967).

51. C.E. Herrick, C.E. Pietri, A.W. Wenzel, and M.W. Lerner, "Improved Amperometric Procedure forDetermining Plutoniwn," Anal. Chern. 44, 377 (1972).

52. W.J. Maeck, M. Kussy, G.L. Booman, and J.E. Rein, "Spectrophotometric Extraction Method Specificfor Plutoniwn," Anal. Chern. 33, 998 (1961).

53. K. Koyama, "Square Wave Polarography of Plutoniwn," Anal. Chem. 32, 523 (1960).

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

j

RAD-NUeInstrument NotesAugust 197.3Page 1

RADIONUCLIDE INSTRUMENT NarES

Included in the following pages are Instrument Notesfor those instruments useful for radionuclide measurements ofvarious kinds. The reader should be aware of the following facts,in order to find all Instrument Notes appropriate for radionuclidemeasurements.

1.) The filing system lists Instrument Notes alphabeticallyby manufacturer.

2.) Instruments for general spectrometry are found elsewhere:under RAD -ALP, RAD-BET, or RAD-GAM, as appropriate. Theseinstruments are often similar to instruments found in thissection (RAD-NUC), the distinction usually being based uponthe manufacturer's advertised specifications. Thus ifa manufacturer claims that an instrument is useful fora specific radionuclide, or for a broad class of nuclides(e.g., "gases"), it is found here; general spectrometryinstruments are elsewhere.

3.) All liquid-scintillation systems are in this section,rather than under beta-detection (RAD-BET).

/' IINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCTritiUlllABCL/Chalk RiverAug. 1972

TritiUlll Air Monitor

ABCL/Chalk River

'-'-"'r---.-~I:

+ 350 .v

r-------------------------- ------,I II II II I

II

CHAMBER ASSEMBLY AEP 1496 II• L -1

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Laboratory area monitor

RAD~NUC

TritiumABCL/Chalk RiverPage 2 Aug. 1972

Stage ofDevelopment



Sampling

Requirements

Features

References

Cost

Remarks

Address

Not commercially available

Flow-through ionization chamber, with compensating chamber for externalgamma compensation. 40-liter volume chamber. Electrometer, dc amplifier,meter or chart recorder output.

Sensitivity: Down to 1 pCi/cm3 of air; 6 ranges, up to 2500 pCi/cm3full scale

Continuous; air, filtered through glass wool, is pumped through chamber at36 liters/min; ion trap between filter and chamber

Power: 115 V acSize: 60" height (150 cm)

1. Response time about two minutes to sudden increase in activity.2. Very insensitive (~10%) to humidity changes.3. Gamma background of 7 mR/hr produces reading of 15 pCi/cm3.

R.V. Osborne and G. Cowper, The Detection of Tritium in Air withIonization Chambers, Report AECL-2604, Chalk River Nuclear Laboratories.


Portable chambers of volumes 0.3 and 1.2 liters also developed by samegroup at Chalk River

R.V. OsborneAtomic Energy of Canada LimitedChalk River Nuclear LaboratoriesChalk River, Ontario, CANADA(613) 584-3311

u ..INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Tritium Urinalyser

AECL/Chalk River MOdel AEP-52l6

RAD-NUCTrititun in UrineAECL/Chalk River 2Aug. 1972

~-

Class

Stage ofDevelopment



Sampling

Performance

Requirements

Features

References

Cost

Laboratory urinalyzer


Sample is placed in input of instrument, then mixed with liquidscintillator, counted by two photomultipliers in coincidence.

Sensitivity: Minimum of 1000 pCi/cm3, maximum of 107 pCi/cm3

of urine

Batch basis. Requires 20 cm3 urine sample.

Accuracy: About ±10%, with about 1% carryover between samplesResponse: Two minutes between introducing sample and readout of activity.Background: About 1000 pCi/cm3Air Supply: 10 cm3/secOutput: Chart recorder, 4-decade logarithmic

Power: 117 VAC, 250 wattsSize: Fills most of one relay rack

1) Automatic processing, with standard and background samples included2) Also capable of assaying tritium activities in other samples

1) R.V. Osborne, "Performance of an Automatic Analyser for Tritium inUrine," Health Physics, 18, .87 (1970)

2) R.V. Osborne, ".(\utomaticUrinalyser for Tritium AEP-52l6," ReportAECL-2702, Chalk River Nuclear Laboratories (1968)


INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCTritiwn in UrineAECL/Chalk River 2Page 2 Aug. 1972

Address R.V. OsborneAtomic Energy of Canada LimitedChalk River Nuclear LaboratoriesChalk River. Ontario. Canada(613) 584-3311

, ,,~~) t.)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Isotope Counter

Beckman a-Mate II

RAD-NUCTritium, Carbon-14BeckmanNov. 1972

Class



Sampling

Performance

Requirements

References

Cost

Address

Laboratory, Portable

Single-sample, liquid scintillation counter. External standard countsin two windows and the ratio of these counts is used for quench calibration.

Tritium Efficiency > 57%Carbon-14 Efficiency > 90%Carbon-14 spillover into tritium < 25%

Accepts one standard 20 ml liquid scintillation vial (glass orpolyethylene) or flow cell accessory

Volume: 8 to 18 mlTemperature: Ambient to 25°COverall System Resolving Time: '" 0.5 llsecCoincidence Gate Resolving Time: '" 20 nsecDead Time Loss: 1% at system limit of 106 cpm

Power: 120 or 240 V ac, ± 10%, 1 amp, 50 or 60 HzSize: 45.7 cm W, 71.6 cm D, 72.5 em H (18", 28.2", 28.5")Weight: 147.2 kg (325 lb)


$4150.

Beckman Instruments, Inc.2500 Harbor BoulevardFullerton, CA 92634(714) 521-3700

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Trititun (Water) Monitor

Beckman 18-100, LS-200, LS-300 Series

RAD-NUCTrititun, Carbon-14Beckman 2Jan. 1973

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCTritium, Carbon-14Beckman 2Page 2 Jan. 1973

Class


Sampling

Features

References

Laboratory, Automated Sample Counter, Printer.

Liquid scintillation systems. Matched RCA photomultiplier tubes incoincidence detect light from sample. Output in cpm (digital display)and by log rate meter.

LS-IOO 1S-200 LS-300Series Series Series

Tritium Efficiency 60% 63% 63%Carbon-14 Efficiency 90% 90% 90%Carbon-14 Spillover into Tritium 12% 10% 10%Current at 115 V ac 4.5 A 8 A 8 A

Width 27" 47" 47"Depth 29" 33" 33"

Height 55" 58" 58"Weight 600 lb 950 lb 1000 lb

Batch sampling capacity is 100, 200, or 300 samples.

1. Coincidence gate resolving time: 20 nsec.2. Detector well: one standard 20 cm3 vial or flow cell accessory.3. Gain control feature.4. External standardization by ratio of counts in two calibrated windows.5. Automatic quench calibration (models LS-150, LS-250) compensates for

varying quench by adjusting system gain for each sample.6. Computer compatibility, many accessories and options available.


Cost Model

LS-IOO Series

18-200 Series

LS-300 Series

Price

$ 6,900. - $13,120.

$11,550. - $19,200.

$12,550. - $20,200.

Address Beckman Instruments Inc.2500 Harbor BoulevardFullerton, CA 92634(714) 521-3700

,-:!!"~ CP

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Trititun Flow Cell

Beckman Discrete Sampling Flow Cell

RAD-NUCTrititunBeckman 3Oct. 1972

Class Laboratory



Sampling

Performance

Requirements

Features

References

Liquid water sample is mixed with a dioxane-based liquid scintillator ina mixing chamber. The mixed solution is then pneumatically transferred toa probe-vial assembly, ready to insert into one of the Beckman liquidscintillation systems (see separate Instrument Note).

Sensitivity: Minimtun Detectable Tritium Concentration:25 pCi/ml of water

Discrete sample from flowing stream

Sample Flow Rate: 0.5 ml/minuteScintillator Flow Rate: 7 m1/minute

Power: UnlmownSize: UnlmownWeight: Unknown

See discussion in text on'Trititun Monitoring."

1) Manufacturer's specifications2) P. Ting and M.K. Sullivan, "Reactor Coolant Monitoring with a Discrete'

Sampling Flow Cell Liquid Scintillation System," Report No. 558,Beckman Instruments, Inc.

Cost

Address

For Use With Beckman S-Mate IIInterface: If Used With LS-100 or

18-200 Series Instrument

Beckman Instruments Inc.2500 Harbor Blvd.Fullerton, CA 92634(714) 521- 3700

$1670

265

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Tritium in Air Monitor

Bendix/Sandia Model T446

Portable

RAD-NUC.Tritium in AirBendix/SandiaAug. 1972



Sampling

Performance

Requirements

Features

References

Cost

Flow-through ionization chamber, output feeds vibrating-reed electrometer.Signal is amplified. Electrostatic precipitator at input.

Lower limit 5 pCi/cm3 of air; upper limit 10 )l Ci/em3 of air.Seven-decade ranges.

Continuous

Accuracy: Linearity ±5%, maximum error ±15 of full scale on any rangeTemperature: 00 F to 1350 F, with extended operation down to -400 F with

NiCd batteries

Power: 115 VAC, or 10 D cells (24-hour lifetime), or rechargeableNiCd F cells (75-hour lifetime)

Size: 6.5" x 11.6" x 8.8" (16 x 29 x 22 em)Weight: 20 to 23 lb (9 to 11 kg)

1) Electronics all solid-state, on printed circuit boards2) Electrostatic precipitator at input, and filter to eliminate ionizing

aerosols3) Adjustable alarm level4) Either portable (batteries) or stationary (ac power)5) Fail-safe failure indicator6) Automatic range changing

1) Sandia Laboratories Report SC-M-68-2452) Sandia Laboratories Report SC-M-67-2443) R.P. Baker and R.D. Richards, "Reliable and Versatile Instrumentation

for Detection of Tritium Hazard Designed for Military Application,"available from Sandia Laboratories

$8600.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCTritiUlJl in AirBendix/SandiaPage 2 Aug. 1972

Remarks

Address

1) Extremely versatile instrUlJlent with multitude of features.2) Built by Bendix on contract for the ABC. Available from Bendix on a

contract basis only. Non-ABC customers must order through the ABC.

Design Agency:Sandia LaboratoriesBox 5800Albuquerque, NM 87115Attn: Reo De Pew(505) 264-8211

Production Contractor:Bendix CorporationKansas City DivisionBox 1159Kansas City, MO 64141Attn: Order Control Supervisor ,D/2l3(816) 363-3211 - Extension 2465

ABC:U.S. Atomic Energy CommissionAlbuquerque Operations OfficeP.O. Box 5400Albuquerque, NM 87115Attn: Director, Space and Special Programs Division(505) 264-8211

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Tritium Urinalysis MOnitor

Bendix/Sandia Model T449

RAn-NUeTritium in UrineBendix/Sandia 2Jan. 1973

T449 UrinalyzerInstnnnent With T446 Tritium MOnitor

URINALYSIS GAS GENERATION

CARTRIDGE CONFIGURATION

ABSORBERFINELY DIVIDED

CALCIUM

TUBINGLEADING TOION CHAMBER

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Portable

RAD-NUCTritium in UrineBendix/Sandia 2Page 2 Jan. 1973



Sampling

Perfonnance

Requirements

Features

References

Remarks

Cost

Address

Metallic calcium (disposable cartridge) reduces water in urine. Evolvedhydrogen gas fills an ionization chamber. For use with the T446 TritiumMOnitor (see separate section).

Sensitivity: Down to 20,000 pCi/em3 of urine

20 em3 batch sampling; requires five minutes per sample.

Accuracy: Maximum error ±25 of full scale, or ±20,000 pCi/em3 , whicheveris greater

Temperature: 35-l35°F

Size: 12.5" x 10" x 14" (32 x 25 x 35 em)Weight: 18 lb (8 kg) including 12 cartridgesCartridge: 7" length, 1.5" diameter (17 x 37 em)

1. For use with T446 Tritium MOnitor.2. Useful in remote or emergency situations.

1. Sandia Laboratories Report SC-M-68-245.2. Sandia Laboratories Report SC-M-67-244.3. R.P. Baker and R.D. Richards, ''Reliable and Versatile Instrumentation

for Detection of Tritium Hazard Designed for Military Application";available from Sandia Laboratories.

Built by Bendix on contract for the ABC. Available from Bendix on acontract basis only. Non-ABC customers must order through the ABC.

By contract only

Design Agency:

Sandia LaboratoriesBox 5800Albuquerque, NM 87115Attn: Reo De Pew(505) 264-8211

Production Contractor:

Bendix CorporationKansas City DivisionBox 1159Kansas City, MO 64141,Attn: Order Control Supervisor, D/2l3(816) 363-3211 - Extension 2465

ABC:

U. S. Atomic Energy ConnnissionAlbuquerque Operations Office·P.O. Box 5400Albuquerque, NM 87115Attn: Director, Space and Special Programs Division(505) 264-8211

CJ

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Urani~ Enrichment .Monitor

Eberline MJdel SAM-2

RAD-NUCUraniumEberlineJuly 1973

Class



Performance

Requirements

Features

Portable

Scintillation crystal NaI (Tl) doped with 21+ 1Am, photomultiplier tube, twosingle channel analyzers, amplifier, high voltage gain control circuit, scaler,timer, ratemeter and digital readout.

Energy Range: ~timized for the detection of the 185 keY ganuna emitted by2 sU, may be used for other energies.

Rate: 500, 5000, 50,000, and 500,000 cpm, linearThreshold: 0 to 1.0 volts, calibratedWindow: 0 to 1.0 volts, calibrated

Pulse Height Resolution: (with RD-19) 'V 15% FWHM at 185 keYTemperature: 0° to 60°C (32° to 140°F)Timer: From 0.1 to 50 minutesResponse Time: 1 to 13 sec continuously variable, reset switchLinearity: ±5% of full scalePaired Pulse Resolution: 'V 4 ~sec

Power: 115 or 230 Vac switch selectable, 0.25 AmpsBattery: 7.5 V to 14 V at 1.0 Amps

Size: Detector -- 6.6 cm dia, 24.5 cm L (2.6" D, 9.6" L)Electronics -- 11.5 em H, 24.5 cm D, 26.8 cm W(4.5" H, 9.6" D, 10.5" W)

Weight: Detector -- 1.1 kg (2.5 lb)Electronics -- 3.2 kg (6.8 lb)

Mode switch: Timed-stop-manualTest circuit, voltage stabilization circuit, read either channel, add bothchannels, subtract one channel, scaler and ratemeter displays, preset countingtimes.Accessories: Battery pack, lead shield, carrying case.MJdel RD-19 Stabilized Scintillation Detector: 2-inch diameter x 1/2 inchthick NaI(Tl) crystal doped with 21+ 1Am, with 2-inch, 10 dynode, Sll responsephotomultiplier tube. Dynode resistor network and magnetic shield built intodetector. Weighs 2-1/2 lb.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCUranilDllEberlinePage 2 July 1973

Features (Cont'd)

References

Model RD-20 Stabilized Scintillation Detector: Same as Model RD-19, but withthin window crystal and lower gamma equivalent energy of the 24 lAm for lowenergy gamma measurements. Weighs 2-1/4 lb.

Model RD-2l Stabilized Scintillation Detector: 5-inch diameter photomultiplier tube and crystal version of the RD-20, also for low energy gammameasurements.

Neutron Probe: Model RD-18 Directional Fast Neutron Detector (not stabilized).

Model BP-4 Battery Pack: 12 volt, 7.5 amp-hours, rechargeable battery incarrying case. Includes charger and connecting cables. Weighs 8 lb;

Lead Shield for RD-19: 3/16" thick aluminum encased lead shield with collettype retention to the detector. Has easily interchangeable end plates forvarying collimation. Weighs 5-1/2 lb. .


Cost

Address

SAM-2

Eberline InstTlDllent Corp.P.O. Box 2108Airport RoadSanta Fe, NM 87501(505) 982-1881

$2,650.

i j.

~.) ~,.i

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

8sKr Liquid Scintillation System

EPA Eastern Envirorunental Radiation Ulb

Laboratory

RAD-NUCKrypton-8sEPA, EERLAug. 1972

Accuracy:

.. J~

Stage ofDevelopment


Sensitivity

Sampling

Performance

References

Address


Krypton gas is concentrated cryogenically, introduced at 500-600 torrpressure and dissolved into a 2s-ml vial filled with toluene-basedliquid scintillator, and counted by a photomultiplier system.

Minimum detectable concentration ~ 1 pCi/m3 of air

Air can be introduced directly into solution at sufficiently highconcentrations.

1. Individual measurements of background 8sKr (in the10 pCi/m3 range) are determined to about ±4%.

2. One cpm above background = 0.1 pei/ml of air

1. R.E. Shuping, C.R. Phillips, A.A. Moghissi, "Low Level Counting ofEnvirorunental 8sKr by Liquid Scintillation," Analytical Chern. 41,2082 (1969); this paper describes the method. -

2. R.E. Shuping, C.R. Phillips, A.A. Moghissi, "Krypton-8s Levels in theEnvirorunent Determined from Dated Krypton Gas Samples," Rad. HealthData and Reports 11, 671 (1970).

R.E. ShupingEPA, Eastern Envirorunental Radiation LaboratoryP.O. Box 61Montgomery, AL 36101(205) 272-3402

Class

LJ

INSTRUMENTATiON

FOR ENVIRONMENTAL

MONITORING

85Kr Liquid Scintillation System

EPA Eastern Environmental Radiation Lab

Laboratory

RAD-NUCKrypton-85EPA, BERL 2Aug. 1972

s-

, )~

Stage ofDevelopment


Sensitivity

Performance

Comments

References

Address


Krypton is separated from gas samples with charcoal and molecular sievecold traps, calcium sulfate, ascarite (NaOH preparation) and a titaniumfurnace (900°C). Sample is then dissolved in liquid scintillator andcounted by a photomultiplier system.

Minimum detectable concentration ~l pCi/m3 air.

Accuracy: Individual measurements of background 85Kr (in the 15 pCi/m3range) are determined to about ±10~.

83mKr is used as a tracer in the krypton separation process. Kryptonrecoveries are in the 80-90% range. About 1 m3 of air can be processedin four hours.

S.L. Cummings, R.L. Shearin, C.R. Porter, "A Rapid Method for Determining85Kr in Environmental Air Samples," page 163 in Rapid Methods for MeasuringRadioactiviff in the Environment, International Atomic Energy Agency,Vienna (1971 .

S. L. CummingsEPA, Eastern Environmental Radiation LaboratoryP.O. Box 61Montgomery, AL 36101(205) 272-3402

i"r

I...} ~-..i "j \J til,) 0 t..J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCKrypton-8sEPA, NERHLAug. 1972

Class

Stage ofDevelopment


Sensitivity

Krypton-8s Ion Chamber Systems

EPA Northeastern Radiological Health Lab

Field Instruments


Flow-through ionization chambers for 8sKr measurements

Chamber Volume Minimum Detectable Concentration 8sKr (pCi/m3)

Sampling

0.5 liters1.0 liters2.8 liters4.3 liters

Continuous

130,000190,00039,00039,000

Performance

Comments

References

Address

Accuracy: ±7% to ±17% (2cr) error on calibration

1. Dry, radon-free air required.2. Radon holdup trap needed.3. Needs frequent maintenance.4. 8sKr concentration is averaged over about 20-30 minute interval

due to radon trap.

D.G. Smith, J.A. Cochran, B. Shleien, "Calibration and Initial FieldTesting of 8sKr Detectors for Environmental Monitoring," DocumentBRH/NERHL 70-4, Northeastern Radiological Health Lab (1970).

EPA, Northeastern Radiological Health Laboratory109 Holton StreetWinchester, MA 01890(617) 729~s700

.. )~,,/

tJ

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

,J';,.

RAD-NUCKrypton-85EPA, NERHL 2Aug. 1972

Class

Krypton-85 G-M Detectors

EPA Northeastern Radiological Health Lab

Field Instruments

\.J

Stage ofDevelopment


Accuracy

Comments

References

Address


Five Geiger-MUller tubes for 85Kr measurements

MinimwnDetectable

WindowConcentr~tion

(pCi/m )Instrument Geometry of Thickness (10 min sample/-

(G-M Detector) G-M Detector Dimensions mg/cm2 10 min background)Eon 8008H 2 window 2" diameter 3.5 12,000

pancakeEon 800lT 1 window 2" diameter 1.4 25,000'

pancakeAmperex 18546 1 window 2" diameter 3.5 27,000

pancakeEon 5l08E cylindrical 5" length, 30. 28,000

1/2" diameterLND 719 cylindrical 5" length, 30. 24,000

1/2" diameter

All probes calibrated ±13% against standard ion chamber.

1. Cylindrical probes are the most rugged.2. Two-window pancake was too fragile for field use.3. All probes are sensitive enough for use near a fuel-reprocessing plant.4. Time-averaging is very short (a few minutes).

D.G. Smith, J.A. Cochran, B. Shleien, "Calibration and Initial FieldTesting of 85Kr Detectors for Environmental Monitoring," DocumentBRH/NERHL 70-4, Northeastern Radiological Health Lab (1970).

EPA, Northeastern Radiological Health Laboratory109 Holton St.Winchester, MA 01890(617) 729-5700

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Tritium Monitor for Air, Water, Urine

EPA Plastic Scintillation System

Schematic Diagram of the Detector

Laboratory

RAD-NUCTritilUllEPAOct. 1972

Stage ofDevelopment



Sampling


Plastic scintillation system, two bialkili photomultiplier tubes incoincidence, single channel analyzer, ratemeter. Scintillator isabout 100 3mm plexiglas rods coated with anthracene or plastic phosphor.

Sensitivity: Air: 20 cpm per pCi/cm3 of airWater: 10 cpm per 1000 pCi/cm3 of waterUrine: Same as waterBackground: About 30 cpm from normal external gamma background

Continuous

Requirements Power:Size:

115 VAC with .fW power supplyDetector about 3" diameter (7.5 cm), 6" length (15 em)

Features

References

Cost

Address

1. Electronic system records only those events with coincidence in30-50 nsec resolving time.

2. Audible and visible alarm feature, variable level.

A.A. MOghissi, H.L. Kelley, C.R. Phillips, J.E. Regnier, "A Tritium MOnitorBased on Scintillation," Nuclear Instr. and Methods 68,159 (1969).


EPA National Environmental Research CenterP.O. Box 15027Las Vegas, NY 89114Attn: A.A. Moghissi(702) 736-2969

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

.• ij ,; U

RAD~NUC

Tritium, C-14, A-4l, Kr~85

Johnston LabsAugust 1973

Class



Perfonnance

Requirements

Features

References

Radionuclide Gas Monitor

Johnston Labs· Triton 955B

Laboratory or stationary ionization chamber

Positive displacement ptDllp draws air through submicron filter and electrostatic precipitator, then into two flow-through ionization chambers. Signalamplified in electrometer circuit. Two identical sealed chambers measureexternal gannna flux, which is subtracted electronically.

Tritium Ranges: 0-10, 100, 1000, 10,000 ~ Ci/M3

Carbon-14 Ranges: 0-2, 20, 200, 2000 ~ Ci/M3

Gannna Ranges: 0.05,0.5, 5,50 mr/hour

Accuracy: ±10% of full scale, reproducibility ±2%Zero Drift: After 15 minute warm-up less than 2% of FS in 24 hoursTime Constants: 15 or 45 secondsGannna Compensation: Up to 5 mr/hour for uniform external fieldAir Flow: 2 to 10 liters/minute, adjustable 0.5 micron filter

Power: 115/230 Vac, 100 W, 50/60 HzSize: 19.6" x 14.8" x 21.6" (50 x 37 x 55 em)Weight: 67 lb (30 kg)

Alarm for fail-safe operation, variable set point, fail-safeCleanable chambers, recorder output, remote operation modeSolid-state circuitry

1) Manufacturer's specifications2) J.R. Waters, Johnston Labs Internal Report ItJLI-506, "Pitfalls and

Errors in the Measurement of Tritium in Air"

Cost Model 955B $2990.

\~.J

Remarks

Address

Very high sensitivity

Johnston Laboratories Inc.3 Industry LaneCockeysville, MD 21030(301) 666-9500

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Tritium Monitor

Jolmston Labs Triton 1055B

RAD~NUC

TritiumJolmston Labs 2July 1973

Class Portable



Performance

Requirements

Features

References

Cost

Address

Positive displacement pump draws air through submicron filter and electro~

static precipitator, then into flow-through ionization chamber. Signalamplified in electrometer circuit, sealed chambers measure external gammaflux, which is subtracted electronically.

Tritium Ranges: 50, 500, 5000, 50,000 ~ Ci/M3

Gamma Ranges: 0.25, 2.5, 25, 250 m~/hr

Accuracy: ±10% of full scale, reproducibility ±3%Zero Drift: After 15 minute warm-up less than 2% of FS in 24 hoursTime Constants: 20 secGamma Compensation: Up to 5 mr/hour for uniform external fieldAir Flow: 2 liters/minute, 0.5 micron filter

Power: 115/230 Vac, 50/60 HZ, 25 Watts, or NiCd battery, 6 hoursSize:Weight: 14 kg (30 1b)

Alarm for fail-safe operation, variable set point, fail-safeCleanable chambers, recorder output, remote operation modeSolid-state circuitry, tritium calibrator accessory


MOdel 1055B $2,295.

Jolmston Laboratories, Inc.3 Industry LaneCockeysville, MD 21030(301) 666-9500

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Tritium Gas Monitor

Johnston Labs Triton 1125

RAD-NUCTritiumJohnston Labs 3

,Aug. 1972

Class Portable



Performance

Requirements .

Features

References

Cost

A positive displacement pump draws air through a submicron filter andelectrostatic precipitator removing interfering particles, ions, humidityand smoke. Air then goes into the flow-through ion chamber. Ionizationwithin the chamber is detected and amplified by an electrometer circuitwhich is calibrated to read ~ curies/M3 of tritium. Identical sealed ionchamber is used to subtract the external gannna flux, with subtractionperformed electronically.

Tritium Ranges: 100,1000, and 10,000 ~ Ci/M3

Accuracy: ±15% full scaleZero Drift: After 5 minute warm-up less than 5% FS in 30 minutes; less

than 3% FS in 4 hoursTime Constant: Approximately 20 secondsGannna Compensation: up to 5 mR/hr for uniform radiation field,Decontamination: Reads less than 5 ~ Ci/M3 in 5 minutes after 15 minute

exposure to 1000 ~ Ci/M3 of tritium gasAirflow: Approximately 2 liters/min.Operating Temperature: +400 F to +1500 F

Power: 109-121 V ac, 50-65 Hz, 5 W, or batterySize: 7.2 x 12.7 x 14.2 inches (18 x 32 x 36 em)Weight: 17 lbs (8 kg)

Automatic changeover to battery operation on power failure. Militarytype construction. Suitable for other beta emitting fission productgases: C14, A4l, Rn222 , S35, Kr 85, Xel~3. .

1) Manufacturer's specifications2) J.R. Waters, Johnston Labs Internal Report #JLI-506, "Pitfalls and

Errors in the Measurement of Tritium in Air"

$1995

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCTritiumJohnston Labs 3Page 2 Aug. 1972

Remarks

Address

Other models available. Instrument use high above sea level will requirea correction factor due to reduced air density in chamber. "Designedfor military and other rugged requirements and does not have adequatesensitivity for health monitoring" (Private connmmication, L. Gevins).Carrying case and straps included.

Johnston Laboratories Inc.3 Industry LaneCockeysville, MD 21030(301) 666-9500

u

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

., ) 0

RAD-NUCTrititunJolmston Labs 4August 1973

Class Mobile

Radionuclide Monitor

Jolmston Labs Model LB 124



Sampling

Performance

Requirements

Features

References

Cost

Address

Proportional gas flow-counter probe, counter gas is 75% methane and 25%air, two probes available.

Sensitivity: Model LB 6280 -- '" 50 pCi/em2 for H3

Model MZ 94/190 -- <1.0 pCi/cm2 for ~'s-- <2.0 pCi/cm2 for ~'s

Range: 102 , 103 , 104 , 105, 106 cpm, semi-log scale

Efficiency: Model LB 6280 -- '" 40%Model MZ 94/190 -- '" 25%

Window: Model LB 6280 -- 0.16" x 1.42", 0 mg/em2

Model MZ 94/190 -- 3.7" x 7.48", 0.4 mg/cm2

Temperature Range:Time Constant: I, 4, 20 sec, selectable

Power: 115 Vac, 50/60 Hz, 14 WattsBatteries -- 2 NiCd, 15 hrs

Probe Size: Model LB 6280 -- 9 cm W, 15 em D, 16 em H (3.5" x 5.9" x 5.1")Model MZ 94/190 -- 12.5 em W, 24 em L, 2.7 cm H (4.9" x 9.5" xLI")

Probe Weight: Model LB 6280 -- 2 kg (4.4 lb)Model MZ 94/190 -- 2.2 kg (4.7 lb)

Recorder output, audible count rate indicator


Model LB 124 $2,195.*

Jolmston Laboratories, Inc.3 Industry LaneCockeysville, MD 21030(301) 666-9500

*As of the present price list; changes in price may be made subj ect toregulations.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCRadon-222 &DaughtersJohnston Labs 5 .August 1973

Radon Analysis System

Johnston M:>dels RCTS- 2, LAC- 2, LLRC- 2

. )\.-.7

M:>del RcTS-2 M:>del iAc- 2

M:>del LLRC-2

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCRadon-222 &DaughtersJohnston Labs 5Page 2 August 1973

Class



Sampling

Laboratory

Radon is concentrated and purified in Model RCTS-2, and transferred toMOdel LAC-2, a Lucas chamber. Scintillations produced in the chamber arecounted by a photomultiplier in the LLRC-2 analyzer.

1 pCi of radon yields 5 cpmBackground is 0.1 cpm

Batch, traps to remove water and CO2

Performance Reproducibility: ±5%Collection Efficiency: 95%

Requirements LLRC-2Power:Size: 16" H, 23" W, 20" DWeight: 95 1b

RCTS-2

40" H, 28" W, 25.5" D229 1b

5" H, 2" dia

Features

References

Solid state electronics, automatic tape printout/timing/recycling,accessories available.


Cost

Address

RCTS-2 Radon Concentrator (less vacuum pump)LAC-2 Radon Counter (quartz window)LLRC-2 Radon Analyzer (electronic console)

Johnston Laboratories, Inc.3 Industry LaneCockeysville, MD 21030(301) 666-9500

$5,995.295.

4,195.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCTritium in AirLawrence Livermore LaboratorySept. 1972

Tritium in Air MOnitor

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Portable

RAn-NUCTritium in AirLawrence Livennore LaboratoryPage 2 Sept. 1972

Stage ofDevelopment


Sensitivityand Range .

Sampling

Requirements

Features

References

Cost

Address


Large-area, thin-window gas-flow proportional counter. Two-countersystem. First counter has Fonnvar window thin enough for tritium betapenetration, while second counter has aluminized Mylar window opaque totrftium betas. Window is porous to counting gas (propane); flow is frompositive inside pressure. Instrument is more responsive to HrO than Hr.

Sensitivity: About 5 pCi/cm3 of air in 3 mR/hour gamma flux

Continuous

Power: NiCd batteries (rechargeable)Size: 9" x 9" x 13"Weight: 20 lb

1) Can count tritium while rejecting higher-energy betas (Ar-4l, Kr-85).2) At flow rate of 55 cm3/min, propane bottle lasts 26 hours.

S. Block, D. Hodgekins, and O. Barlow, "Recent Techniques in TritiumMonitoring by Proportional Counters," Report UCRL-5113l, Lawrence LivennoreLaboratory

Not commercially availaqle

Lawrence Livennore LaboratoryLivennore, CA 94550Attn: S. Block(415) 447-1100

~_ 4

.~-",! , - .)

.. )"

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Tritium Urina1yzer

Lawrence Livennore Laboratory

RAD-NUCTritim in UrineLawrence LiVe:l'll'lore Laboratory 2Sept •. 1972

.', .

10 cm3

Sample in

• 20 cm3

syringe

#21 needfe

Filter flask containing1/4-in. lumps CaC2

LE8400Timer scaler

Charge sensitivepreampl ifier

Detector

~ Printer--1'--------........1

f----f HV power suppl y

Class

INSTRUMENTATION

FOR ENVIRONMENtAL

MONITORING

Portable

RAD.,NUCTritiwn in UrineLawrence Livermore Laboratory ZPage Z Sept. 197Z

Stage ofDevelopment



Sampling

Performance

Requirements

Features

References

Cost

Address


Calcium carbide and water react (CaCZ + ZHZO -+- C2HZ + Ca (OH) 2)' Acetyleneis then used as the counting gas in a proportional counter. With tritiwnin urine, C2HT is the counting gas.

Sensitivity: 1000 pCi/cm3 of urine

Batch basis, 10 cm3 urine per sample

Accuracy: ±5% to ±10% deviations per sample

Power: NiCd batteries (rechargeable)Size: 6" X 18" X ZO" [suitcase]Weight: 20 lb

1. Reaction vessel is a 150 cm3 vacuum filter flask sealed at top with arubber stopper.

Z. Hypod.ennic needle used to insert 10 cm3 of urine into vessel.

3. Water-saturated acetylene is dried by flow through ZO-30 mesh calciwncarbide in aluminum cylinder.

4. Proportional counter is identical to that described in anotherinstrument note except it is made gas-tight with aluminum-covered sides.

1. S. Block, D. Hodgekins, and O. Barlow, Recent TechnijUeS in TritiwnMonitoring b~ Proportional Counters, Report UCRL-Sll 1, LawrenceLivermore La oratory.

Z.S. Block and J .E. Dixon, A Portable Tritium-in-Urine Monitori Kit,ReportUCRL-50007-7Z-l (Hazar s ontrol ogress Report No.

Not Commercially available

Lawrence LNermoreLabor~ory

Livermore, CA 94550Attn: S. Block(415) 447-1100

Class

--,~

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

85Kr Liquid Scintillation System

Mound Laboratory

Laboratory

RAP-NUCKrypton-85Mound LabJan. 1973

Stage ofDevelopment

.Principleof Operation

Sensitivity

Sampling

Performance

References

Address


Sample gas is expended into evacuated Vial, introduced at 25 torr pressureand dissolved into a 25 m1 polyethylene vial filled with toluene-basedliquid scintillator, and counted by a photomultiplier system.

Minimum Detectable Concentration: "15 pCi/cm3 of air or any gasCounting Efficiency: 92.5% of 85Kr betas are counted above threshold

Limit of :::25 m1 of krypton can be introduced

Accuracy: Individual measurements to ±2.2%

1. M.L. Curtis, S.L. Ness, 1.L. Bentz, "Simple Teclmique for RapidAnalysis of Radioactive Gases by Liquid Scintillation Counting,"Analytical Chem. ~, 636 (1966); this paper describes the method.

2. R.E. Shuping, C.R. Phillips, A.A. Moghissi, "Low Level Countingof Environmental 85Kr by Liquid Scintillation," Analytical Chem. 41,2082 (1969).

M.L. CurtisMonsanto Research CorporationMound LaboratoryP.O. Box 32Miamisburg, OH 45342(513) 866-7444

t.)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

,)

8SKr Plastic Scintillation System

New York State Department of Public Health

RAD-NUCKrypton-8SNew York StateAug. 1972

Class Laboratory

Stage ofDevelopment


Sensitivity

Sampling

Performance

References

Address


Krypton gas is concentrated using vacuum-cryogenic techniques, introducedinto a 4-cc glass vial containing plastic scintillator shavings, andcounted by a photomultiplier tube.

Minimum detectable concentration = 1 pCi/m3 of air.Counting Efficiency: 94% of 8SKr betas are counted above threshold.

Sample of about O.S m3 of air, concentrated to O.S ml of krypton, canbe counted.

Accuracy: Individual measurements of background 8SKr (in the 10 pCi/m3range) are determined to ±10%.

Interferences: Methane must be removed by burning with added °2,N2, °2, and CH4 did not affect counting efficiency.

N.r. Sax, J.D. Denny, R.R. Reeves, ''Modified Scintillation CountingTechnique for Determination of Low Level 8SKr," Analytical Chern. 40,19l5 (1968). --

N.r. SaxRadiological Sciences LaboratoryNew York State Dept. of HealthAlbany, NY 12201

R.R. ReevesRensselaer Polytechnic InstituteTroy, NY

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

.-.-.,..,.}'"

RAD-NUCTritiumNuclear EnterprisesDec. 1971

Tritium in Air Monitor

Nuclear Enterprise Model 1762

Class



Sampling

Performance

Requirements

Features

Cost

Address

Portable, hand-held

Ion chamber, amplifier, meter read-out

Energy sensitivity:Range 10 to 15,000 pCi/cm3Interferences:

Continuous

Meter accuracy:Drift: 2%Temperature range:

Power:Size:Weight:

Nuclear Enterprises Inc.935 Terminal WaySan Carlos, California 94070(415) 593-1455

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

u

Ttitium in Air Gas Monitor

Nuclear Enterprise Model 1762A

RAD-NUCTritium, airNuclear Enterprises 2Mar. 1972

Class



Performance

Portable, hand-held radioactive gas monitor

A dual concentric gamma compensated ionization chamber, which enablesmeasurements of fIfO (tritated water vapor) and other radioactive gasesin air. Current from the chamber is measured. .A dust filter and anelectrostatic precipitator is used for the removal of small ionizationparticles and gaseous ions to ensure that the current measured is duethe actual radioactive disintegrations within the ionization chamber.

Range: 10-50, 150, 1500, and 15,000 pCi/em3 of fIfO in air

Gas Meter ReadinR" for 1 MPC

HTO 5 pCi/em3

Argon 41 4 pCi/em3

Krypton 85 10 pCi/em3

Radon 21. 5 pCi/em3

.Xenon 133 40 pCi/em3

Accuracy: ± 20% of reading above 1 MPC (MPC of fIfO in air is5 pCi/em3 in England)

Temperature coefficient: ± 1% of full scale per 10°C change

G._

Requirements

Cost

Power:

Size:Weight:

Mallory Batteries - RM-42-R, (500 hrs); TR-134-R, (400 hrs);TR-134-R, 2 ea. (200 hrs)

Everyready Batteries - Type 126, 3 ea., motor, (8-9 hrs)29.8 em H, 20.3 em W, 64.5 em L (11.75", 8", 25.25")12.25 Kg (27 lbs)

~)

Address Nuclear Enterprises Ltd.935 Terminal WaySan Carlos, Calif. 94070(415) 593-1455

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Iodine 131 Monitor

Nuclear Enterprise NE 8423

Portable

RAD-NUCIodineNuclear Enterprise 3Dec. 1971



Sampling

Perfonnance

Requirements

Features

Cost

Address

Gamma detector and three discriminators select 1-131 energyfission products, meter read-outs.

Energy Sensitivity:Range: 0.007 ~ Ci to 0.65 ~ CiInterferences:

Continuous, sample size 7 em dia., 6 em thick

Accuracy:Temperature range:Response time:

Power: 12 V d.c. car batterySize:Weight:

"Subtraction" electronics displays 1-131 in presence of higher andlower energy fission products. Rate meters display channels A,B,C,and B- (A+C)

Nuclear Enterprise Inc.935 Tennina1 WaySan Carlos, California 94070(415) 593-1455

f'\.;

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

;)

Air Radiation Monitor

Nuclear Measurements AM-21

RAD-NUCIodineNuclear MeasurementMar. 1972

Class



Sampling

Performance

Requirements

Features

Cost

Remarks

Address

Field

The monitoring system consists of two parts, the pump system and the detecting system. Housed within a lead shield assembly is a gamma scintillationdetector used for detecting gamma emitters below 1 MeV and a particulatecollector; as the particulate matter builds up, the detector converts theionizing events into pulses which are counted on ratemeter~ also air isentering and leaving the lead housing at a flow rate from 3-10 cfrn throughthe filters for deposition of particulates.

Count rate will be 318 cpm for Iodine 131 at 10% yield, 5 cfrn airflow rate,and 10-10 ~c/cc constant activity.

Airflow through filters and charcoal cartridge

Ratemeter accuracy: ±10% of actual input cartridgeTime constant: 200 seconds at 50 clm to 1 second at 50,000 clmStability: Drift not more than ±2% daily, ±20% annually except in narrow

window spectrometry

Power: 90-130 V ac, 60 Hz, 5-7 ampSize: 53 ern X 1 Mx 1 M (21" x 39" x 39")Weight: 250 Kg (550 1bs)

Graphic recorder provision, alarm controls

$4390 with Esterline-Angus recorder

Other air monitors available similar to the above are given in thefollowing table.

Nuclear Measurement Corporation24260 North Arlington AvenueIndianapolis, Indiana 46218(317) 546- 24:1.5

INSTRUMENTATION

FOR ENVIRONMENTAL·

MONITORING

NMC Air Monitors

RAD-NUCIodineNuclear MeasurementPage 2 Mar. 1972

MODEL RADIATION MONITORED PRICE DETECTORS RECORDER FIXED FILTERSA - 20 SERIE~

AM-ZA Alpha $2740 SC-2a 1 Single Channel 1 C/Mor 1 Rustrak

AM-3A $3220 SC-ZA 1 Single Channelor 1 Rustrak

AM-2B Beta $2960 SC-2B 1 Single Channel 21 CIMor 1 Rustrak

AM-3B Beta $3440 SC-2B 1 Single Channelor 1 Rustrak

AM-2D Gross Beta-Gannna $2860 DGM-2 1 Single Channel 21 C/Mor 1 Rustrak

AM-3D Gross Beta-Gannna $3415 DGM-2 1 Single Channel",. ,-

AM-2F Alpha, Beta, Gannna $3010 FGM-2 1 Single Channel 30 C/Mor 1 Rustrak

AM-3F Alpha, Beta, Gannna $3580 FGM-2 1 Single Channelor 1 Rustrak

AM-2G Gannna $3780 SC-2-2S 1 Single Channel Gross 128 CIMor 1 Rustrak SPEC. 10 CIM

AM-3G Gannna $4410 SC-2-2S 1 Single Channelor 1 Rustrak

AM-21 Iodine $3890 SC-2-1S 1 Single Channel Gross ·97 CjMor 1 Rustrak SPEC 10 CIM

AM-31 Iodine $4530 SC-2-1S 1 Single Channelor 1 Rustrak

AM-221 Iodine + Alpha or Beta $5450 SC-2-1S and 1 Dual Channel Iodine 10 CIMor Gannna DGM-2 or or 2 Rustrak GROSS 97 CIM

AM-331 $6015 PC-21-FW .,

AM-2P Alpha or Beta $3310 PC-21-FW 1 Single Channel a.<;.1 CIMor or 1 Rustrak b <3D C/M

AM-3P Alpha + Beta $3880 PC-21-FW "AM-22P Alpha +Beta separately $3780 PC-21-FW 1 Dual Channel l\<.1 CIMAM-33P . but simultaneously $4360 PC-21-FW or 2 Rustrak Jf<30 C/M

PAPM-ll Plutonium $4580 SC-2A " 10 CIM

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

NMC Air Monitors

RAD-NUCIodineNuclear MeasurementPage 3 Mar. 1972

MJDEL MOVING FILTER MJVING FILTER FIXED FILTER MJVING FILTER MJVING FILTERSA-30 SERIES SA-30 SERIES SA-3L SA-30 SERIES SA-3L

AM-2A - - 20% - -

AM-3A 1 C/M 1 C/M - 20% 11%

AM-2B - - 32% - -

AM-3B 21 C/M 40 C/M - 32% 18%

AM-2D - - 10% - -

AM-3D 21 C/M 30 C/M - 10% 5.7%

AM-2F - - 35% - -

AM-3F 30 C/M 30 C/M - 32% 17%

AM-2G - - 19% - -

AM-3G GROSS 128 CjM GROSS 120 C/M - 19% 8%Spec. 10 C/M Spec. 35 C/M

jAM-21 - - 17% GROSS - -3% IODINE

AM-31 GROSS 97 C/M IODINE 30 C/M - 10% GROSS 10% GROSSSpec 10 CjM Gross 115 C/M 15% Iodine 15% Iodine

AM-221 - - 17% GROSS - -3% IODINE

AM-331 IODINE 10 C/M IODINE 30 C/M - 17% GROSS 17% GROSSGross 97 C/M Gross 115 C/M 7;9.: Tnrl;np 39.: Tndine

AM-2P - - a,37% - -

a,<.1 elM$37.5%

AM-3P a,<1 C/M - a,37% a,20%R<30 C/M 8<40 C/M B37% [322%

AM-22P - - a,37% - -[337%

AM-33P a,<10/M a,<10jM - a,37% a,35%[3<30 C/M [3<40 C/M [337% [332%

PAPM-ll 10 C/M - - 35% -

uINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Scintillation Detector

Packard Model 446

RAD-NUCPackardNov. 1972

Class



Sampling

Perfonnance

Requirements

Features

Cost

Address

Laboratory

Cylindrical sample chamber is surrounded by a 4" annUlus of liquidscintillator and six 3" dia. photomultiplier tubes. The tubes aremagnetically shielded and have individual controls for focus and gain.A lead shield surrounds the .entire detector to reduce background. Ahandhold is provided to insure reproducible geometry for foreann counting.

Sensitivity: 60Cot 48% eff.; lSlI t 46% eff.; 59Fet 44% eff.; lS7CS t 38% eff.Range: 150 keY or higher

Aluminum cylinder 4.25" Dt 8" L.


Power:Size: 100 cm Ht 95 cm Wt 79 cm D (39.5" t 37.3" t 31")Weight: 77' kg (about 1700 1b)

Model 446 $8 t900Less shielding and cabinet $5 t855

Packard Instrument Co. t Inc.2200 Warrenville Road-Downers Grove t IL 60515(312) 696-6000 .

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Gas Proportional Counter

Packard Model 894

RAD-NUCTritium, Carbon-14Packard 2Feb. 1973

I~)

Class



Sampling

Perfonnance

Requirements

Features

Cost

Address

Laboratory

Detects tritium or carbon-14 labelled organic compounds as they elute froma gas chromatographic column using a flow-through ion-multiplication detector. A copper oxide furnace oxidizes all organic compounds to carbon dioxide and water to eliminate condensation of high boiling point compoundsin the proportional tube.

Sensitivity: Betas -- 200 dpm/peak carbon-14 labelled compoundsRange: 10 linear ranges, 100 to 100,000 cpm full scale

Five decade log scaleCounting Efficiency: 58% Tritium

80% Carbon-14

Continuous

Accuracy:Temperature: Operates at room temperature

Inlet heating to 300°CFurnace heating to 800°C

Time Constant: Six ranges, 1 to 50 sec

Power: 120-220 Vac (switch), 50 or 60 Hz~ 720 WSize: 35.6 em H, 54.6 em W, 61 em D (14", 21. 5", 24")Weight: 90 kg (200 lb)

Use with Model 7401 Gas Chromatograph or other gas chromatographs whichhave been fitted with stream splitters and heated exit ports.

Background about 30 cpm (variable offset).Variable upper and lower discriminators.Strip chart recorder and scaler output jacks.Right or left-hand capability to couple with any gas chromatograph

$4400

Packard Instrument Company, Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 696-6000

u ,.J

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Liquid Scintillation Spectrometers

Packard MOdel 3390 and Others

RAD-NUeLiquid ScintillatorPackard 3Jan. 1973

Class



Sampling

Perfonnance

Requirements

Laboratory

Liquid scintillation spectrometer system. Matched bialkali photomultipliertubes in coincidence mode detect light; pulse height analysis electronicsprovides spectrum infonnation. Background subtraction done automatically.Automatic calibration ~th external source arrangement.

Sensitivity: UnknownEnergy Range: Can detect any beta, alpha, electron capture, X-ray, or

weak gamma ray isotopes.

300 sample capacity with up to 10 repetitive counts per sample or up to 10preset number of complete cycles for counting all samPles. Also hasautomatic and group counting mode that allows empty samples with a group.

Accuracy: UnknownTemperature: Controlled temperature (maintained ±0.5°C over range

-5°C to +15°C) or ambient temperature

Power: 100-130 or 200-260 V ac, 50-60 Hz, 1000 VA (max)Size: Height 62-1/4 to 67-1/4", adjustable (158 to 171 em); width

4l-l/2to 57" (depending on readout device); depth 31" (79 cm)Weight: 1000 lb (450 kg)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUC1iquidScintillatorPackard 3.Page 2 Jan. 1972

Features

Other Models

References

Cost

Address

1. Three separate pulse-height analysis channels.2. Single-, double-, triple-labeled capability.3. Independent controls for normalizing each photoIIR1ltiplier tube.4. Preset count, background subtraction, low-level reject for each sample

channel.5. Automatic external standardization with radium-226 and americium-24l

sources.6. On-line computation and display of net count rate and standard deviation.7. Gannna pUlse-height capability.8. Automatic sample oxidizers: Models 300,305, and 306 (optional).9. Flow measurement capability using flow-cell and adapter.

10. Model 544 Absolute Activity Analyzer automatically adjusts to optimizecounting rate and background conditions and computes quench-correcteddpm for single- or double-labeled samples (optional).

11. Model 3050 extra shielding package for low-level counting (optional).12. M:Jdel 3090 Automatic Channel Selection (optional).

M:Jdel 3385: Identical to Model 3390 except not available with Model 544Absolute Activity Analyzer.

Model 3375: Identical to 3380 except not available with 544 AbsoluteActivity Analyzer.

M:Jdel 3330: Similar to 3390 except does not have on-line computationfeature, one-source instead of two-source calibration system,some other differences.

Models 2101, 2111, 2211, and 2311: Have fewer features; similar toModel 3320.

M:Jdel 3380: Identical to Model 3390 except 200-sample capacity and notavailable with Model 3090 Automatic Channel Selection.

Model 3320: Identical to Model 3330 except 200-sample capacity.Models 2425 and 2450: Similar to Model 3390 except Servo-TTay sample

changer. Model 2425 has l50sample capacity.M:Jdel 2450 has 450-sample capacity.


Model 3390 $17,095. Model 3330 $15,595.544 4675. 3305 8665.513 1435. 2450 14,500.545 1670. 2425 10,615.542 525. 2311 9565.

3385 16,095. 2211 7990.3380 16,595. 2111 6205.3375 15,595. 2101 5200.

Pa~kard Instrument Gompany Inc.2200 Warrenville RoadDowners Grove, 11 60515(312) 969-6000

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

-_.j

Auto-Gamma Spectrometer

Packard 5000 Series

RAD-NUCSpectrometerPackard 4Jan. 1973

Class



Sampling

Performance

Requirements

Features

References

Laboratory

Automatic 300 sample controlled temperature gamma spectrometer. Twodiametrically opposed NaI(Tl) scintillation crystals, photomultipliers.Automatic background subtraction, low"level count rejection. Threeindependent pulse-height analysis channels with three scalers.

Sensitivity:Energy Range: 10 keY or higher

300 sample capacity changer with repeat, group, and automatic countingmodes. Solid or liquid samples.

Accuracy:Temperature: Maintained within ±0.5°C or ambient operation

Power: 117 or 234 Vac ±10%, 50 or 60 Hz, 10 A (max)Size: l70cmH, 105cmW, 79cmD (67", 41.5", 31")Weight: 680 kg (1500 lb)

1. Preset time/preset count modes up to nine isotopes.2. Coarse and continuous calibrated fine gain adjustment.3. Digital printer output, IBM Selectric or Teletype option.


Cost Model 5320522051205385

$13,25012,73511,190'16,135-

Address Packard Instrument Company Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 696-6000

.- l-~~.. ,.j

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCBeta ScaIUlerPackard S.Nov. 1972

Class



Sampling

Performance

Radiochromatogram SCaIUler

Packard Model 7201

Laboratory

Radioactivity is measured by two windowless G-M tubes arranged in 4 1T

configuration to scan both sides of the strip. Resolution between adjacentspots is controlled by two adjustable collimators.

Sensitivity: Beta emitting nuclidesRange: Ratemeter has 9 linear count ranges and log scale 102 • 103 • 10~.

105 • 106 • and 3 x 102 • 103 • 10~. 105 •

Accepts chromatograms from 0.5" to 2" wide. lengths up to 150 feet. alltypes of papers up to Whatrnan No. 3M<I

Accuracy: See "Time Constants"Temperature: -gOC to +50 oC

Time Constants: From 0.1 to 300 sec (8 settings)ScaIUling Speed: From 0.02 em/min to 200 cm/hr (16 ea.)

INSTRUMENTATION

FOR. ENVIRONMENTAL

MONITORING

RAD-NUCBeta ScannerPackard 5Page 2 Nov. 1972

Requirements

References

Power: 117 or 234 Vac ±10%, 50 or 60 Hz, max. current less than 0.7 Ampsac with Disc Integrator or less than 0.6 Amps ac without DiscIntegrator

Size: 89 em H, 57 em W, 48 em D (35", 22.5", 19")Weight: 98 kg (215 1b)


.~-

Cost Model 7201With disc integrator

$4,700$5,550

Address Packard Instrument Company, Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 696-6000

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Liquid Scintillation System

Searle, Nuclear Chicago, Isocap 300

ISOCAP/300 PROGRAM CHART

RAD-NUCLiquid ScintillationSearle, Nuclear ChicagoSeptember 1973

Solvent system CPM 3 H 14C 32p 36CL 3Ss 3H/14C 3Hp2p 1251 131 1 NOTESsample

Toluene/oil soluble H 18 28 38 78 28 8 10 7A 78 8

L 48 58 68 78 58 8 10 7A 78

Toluene-NCS/dilute H 18 28 38 78 28 8 10 7A 78 8,12acids

L 48 58 68 78 5B 8 10 7A 7B

Imuscle and light H. 1B 2B 3B 7B 2B 8 10 7A 78 4,7,8,12colored tissue

L 4A 5B 6B 7B 5B 8 10 7A 78

II iver and dark H 1B 2B 3B 7A 2B 9 10 7A 7A 4,7,9,12colored tissue

L 4A 5A 6B 7A 5A 9 10 7A 7A

Iblood H lB 5A 38 7A 5A 9 10 4B 7A 4,7,9,12

L 4A 5A 6A 7A 5A 9 10 48 7A

Toluene or xylene + H 1B 2B 3B 78 28 8 10 7A 78 8alcohol or cellosolvelaqueous solutions L 4A 5B 68 78 5B 8 19 7A 7B

Triton-toluene 1:1/ H 1B 2B 3B 38 28 8 10 2B 38 1,2,6,7,water 8,11

L 18 2B 3B 38 2B 8 10 2B 3B

Idilute acids H 18 2B 38 38 2B 8 19 2B 38 1,2,6,7,

L 1B 2B 3B 3B 2B 8 108,11

2B 38

laqueous solutions H 1B 2B 3B 38 2B 8 10 28 3B 1,2,6,7

L 1B 2B 3B 38 2B 8 10 2B8,11

3B

Dioxane (8ray's)1 H 1B 2B 3B 78 2B 9 10 7A 78 3,9,10w"ter

L 1B 5A 6B 78 5A 9 10 7A 78

Idilute acids H 18 28 3B 78 28 9 10 7A 7B 3,9

L 1B 5A 6B 78 5A 9 10 7A 78

laqueous solutions H 1B 2B 3B 78 2B 9 10 7A 78 3,9

L 18 5A 6B 78 5A 9 10 7A 7B

Toluene-Cab-O-Sill H 1B 2B 38 38 2B - - 2B 38 2,5,7suspen ded solids

L 1B 2B 38 3B 28 - - 2B 3B

any Isample on paper H 1B 28 3B 38 2B - - 2B 3B 2,5,7,13

L 1B 28 3B 3B 28 - - 2B 3B

Aqueous/Cerenkov H - - 18 18 - - - - 18 7

L - - 1B 1B - - - - 18

The program analysis windows are designed to meet all routine counting conditions. The samplesolvent systems shown here were prepared in Nuclear-Chicago's research department, and includeda wide variety of applications which were designed to meet the majority of counting requirements.

Program numbers shown on the chart represent the best match of sample system to analysis windowand will give optimum performance. ThenA" or "B" following the program number designates thechannel of interest. For dual label samples both channels are used.

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Laboratory

RAD-NUCLiquid SCintillationSearle, Nuclear ChicagoPage 2 Sept. 1973



Sampling

Performance

Requirements

Features

References

Programmable liquid scintillation system, sample changer, twoscintillator photomultiplier channels

Sensitivity:

Energy Range:

Capacity: 300 samples, bi-directiona1 conveyorProgrammable sample windows

Accuracy:Temperature:Stability: Shift of 14C count rate measured in a dual labelled window

(program 8) shall not exceed 0.25% per °c between 15°C and 30°C.

Power: 115 V J: 10 Vac, 60 Hz, 230 Vac and/or 50 Hz optional.Size: 75 em D, 107 em W, 56 em H (30" x 42" x 22")Weight: 315 kg (700 1b) shipping.

Optional readouts, stands, calculators


Cost

Address

Basic 1socap 300

Searle, Nuclear Chicago2000 Nuclear DriveDes Plaines, 1L 60018

$12,220.

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

o

Liquid Scintillation Systems

RAD-NUCTritium, Carbon-14Searle, Nuclear Chicago 2September 1973

Class



Sampling

Performance

Requirements

Features

References

Laboratory

Liquid scintillation system having controlled temperature enclosure forcounting single labeled, dual labeled, or intermixed samples, two scintillator-photmultiplier detectors, single channel analyzers, and scaler/timers; external standardization and automatic lister. Single channelanalyzers may be pre-set to count sH, l~C, S2p, sH in the presence of l~C,l~C in the presence of sH.

Sensitivity:Energy Range:

Capacity: 300 samplesModes: Manual, one cycle, all samples, groups only, group start

Accuracy:Temperature: Controlled cooling, automatic defrosting

Power: 115 V ± 10 Vac, 60 Hz, 230 Vac and/or 50 Hz optional, 1000 wattsnormal consumption, 2500 start-up.Size: em H, 79 em D, 107 em W ( "H, 31" D, 42" W)

Optional three channel system, automatic self-calibration, standardizationmodule, auto-progrannner module, 'feletypwriteriD, IBM SelectriciD Typewriter,Olivetti Computer calculator, or card punch.


Cost

Address

Basic Mark II

Searle, Nuclear Chicago2000 Nuclear DriveDes Plains, IL 60018

$17,305.

lJ

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

".i

Liquid Scintillation Spectrometer

Searle, Nuclear Chicago Series 6848

RAD-NUCTritium, Carbon~14Searle, Nuclear Chicago 3September 1973

Class



Sampling

Performance

Requirements

Features

References

Cost

Address

Liquid scintillation spectrometer systems having a controlled temperatureenclosure for counting single labeled, dual labeled~ or intermixedsamples of soft beta emitting radioisotopes such Cl and tritium.Three single channel analyzers, optional readouts.

Sensitivity:

Energy Range:

Capacity: 300 samples, samples/min.Modes: Manual, auto stop, all samples, groups only, groups start

Accuracy: ±0.5% of a Ba lSS external standard.Temperature Control:

Power: 115 Vac ±lOV, 60 Hz; 230 Vac and/or 50 Hz optional. 1000 Wmaximum normal power consumption, 2500 Wstart-up.

Size: em H, 78 em D, 105 em W ( "x 31" x 42")Weight: 436 kg (960 lbs)

1. Frost free controlled-temperature system2. Low count sample rejection3. Display hold for isotope peaking4. Options: Automatic lister, auto/subtract background subtractor,

data calculator


Searle, Nuclear Chicago2000 Nuclear DriveDes Plaines, 1L 60018

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Continuous Gas MonitoringTrapelo Model MGP-lA

RAD-NUCGasTrapeloMar. 1972

Class Laboratory



Gas sampler, gamma scintillation or G-M tube detector, filter,ratemeter, alarm, and ptmlp

SENSITIVITIES OF TRACERLAB MG-lA AND MG-ZA GAS SAMPLERSFOR NET SIGNAL EQUAL TO BACKGROUND

Min. Detectable Conc.Type and Energy (MeV) \lc/cc

Activity Gannnas Betas Half-Life MG-IA* MG-ZA**019 1. 3 (64%) 4.5 (30%) 30 Seconds 7 x 10- 7 3.8 x 10-7

0.2 (96%) 2.9 (70%)0.1 ( 4%)

A4l 1. 37 (100%) 1.24 (100%) 110 Minutes 6.25 x 10-7 ' 5.5 x 10-7

Br82y decay 0.46 (100%) 36 Hours - 7.6 x 10-7scheme indoubt

Kr85 0.54 (0.35%) 0.69 (100%) 9.4 Years -4 -73.5 x 10 6 9.6 x 10 61131 0.36 (87%) 0.61 (87%) 8.1 Days 1. 7 x 10- 1.3 x 10-

0.64 (9%)0.72 (3%)

Xe133 0.08 (100%) 0.34 (100%) 5.3 Days 4 x 10-6 2 x 10-6

* With Tracerlab MD-5B Scintillation Detector (250 cpm background, 3" lead shielding).** With Tracerlab MD-12C Large Area Beta-Gamma G-M Detector (40 cpm background 2" lead shielding).

Sampling

Performance

2 to 10 CFM

Continuous operation

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCGasTrapeloPage 2 Mar. 1972

Requirements Power: 110/220 V ac, 50-60 cps, 1 phase, 900 wattsSize: 82 em W, 82 cm H, 62 em D (32.5" W, 32.5" H, 24.5" D)Weight: About 430 Kg (150 lbs.)

Features

Cost

Remote control &Indication. Particulate sampler optional.

$5,000

Address LFE CorporationTrapelo Division1601 Trapelo RoadWaltham, Mass. 02154(617) 890·2000

r----IIIIIIIII

---~---I

\Flow Iindicator I

r;:==== Air 'I-out

IIIII

I I

I II MX -14C Pumping System I'-._---------~

MX-IIB Fixedfilter

Stock

Schematic Flow Diagram. Stock Monitoring SystemMGP -IA System

\Flowindicator

r---IIIIIIIIIIII NeedleI valve

----------1IIII

--==::::::== Air II r -----OUtIIIIIII

I III MX - 14C Pumping Station I_____________-1

MA-IBAir particulate

monitor

Ai r =-=======:::::;"]in-~

Detector

Schematic Diagram, MAP-1B/MGP-IA Particulate andGas Monitoring System

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-NUCParticulateTrapelo 2Mar. 1972

Continuous Particulate Monitor

Trapelo Model MAP-lB

A.'.". 1OUT

IIII

LMX-14C PUMPING SYSTEM I_________ -.----J

I-I

I

II

NEEDLEVALVE

Schematic diagram, MAP-l B.

Class Laboratory

Principle of?peration


Airborne particulate sampler, moving filter, beta detector,ratemeter, alarms, control panel, enclosure, and pump

TABLE ISENSITIVITI ES OF TRACE RLAB MA-l A F ILTE R TAPE TRANSPORT MECHANISM

Half- Energy and Type Min. Detect. Back- NetDetector Activity Life in MeV Conc. /-lc/cc ground Signal

MD-1B C14 5500y 0.15~- 2.5xl0-1125 cpm 25 cpm

4 mg/cm2 TI304 3.5y 0.76~- 1.0xl0-11

Beta-Gamma Sr9O_y 90 20y 0.54~-, 2.2~- 4.5xl0-12

GM Na22 2.6y 0.54~+, 1.28'Y 1.0xl0-11

1131 8.1d 0.36'Y, 0.61~ 1.0xl0-11

Co60 5.3y 0.31~-, 1.3'Y, 1.1'Y 8.0xl0-12

Cs137 33y 0.52~-, 1.1~- lxl0-11

Pm147 2.6y 0.22~- 1.5xl0-11

MD-3BAlpha Scintillation Po210 138d 5.3a lxl0-12 3 cpm 4 cpm

MD-4B C14 5500y 0.15~- lxl0-9 20cpm 20 cpmBeta Scintillation TI304 3.5y 0.76~- 5xl0-12

MD-5B Co60 5.3y 1.1'Y,1.3'Y 9xl0-11 250 cpm 200 cpmGamma Scintillation 1131 8.1d 0.36'Y 0.6W- lxl0-1O

Measured at alf flow rate of 10 scfm, for otherWise uncontaminated fIlters.

Requirements

Cost

Power: 110/220m 50-60 cps, 1 phase, 1000 wattsSize: 82 em W, 101 em H, 62 em D (32.5"W, 40" H, 24.5"D)Weight: About 270 Kg (600 lbs)

$6,000

Address LFE CorporationTrapelo Division1601 Trapelo RoadWaltham, Mass. 02154(617) 890-2000

.. )"-,~.1

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Plutonium-in-Air Monitor

UKAEA - 3030A

RAD-NUCPlutoniumUKAEAAug. 1972

1 MPC-hr = 2.10-12 ~Ci/cm3 for 1 hrMinimum threshold, 0.3 cps =8 mpc-hrMaximum threshold, 3 cps = 80 mpc-hr

Power:Size:Weight:

Class



Sampling

Performance

Requirements

References

Cost

Stationary

Alpha activity deposited on a static filter paper is measured using asilicon detector, amplifier, multiplexer, pulse height selector set toplutonium alphas, ratemeter, array of lamps display, aild warning lamp.

Energy Range:Activity Range:

Maximum Number per Installation: 20

Accuracy:Temperature:Air Flow: Up to 100 liters/min

Use type 2015

3.15 kg (7 lIbb) for head amplifier sensorkg ( ) for electronics ,


~-

Address Nuclear Enterprises Ltd.Bath Road, BeenharnReading, Berks, ENGLANDTel.: Woolhampton 2121

Nuclear Enterprises Ltd.935 Terminal WaySan Carlos, CA 94070(415) 593-1455

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

}

RAD-NUCUraniumUKAEA 2Oct. 1972

lJraIll.UJIl Survey Monitor

UKAEA Model 3086

Class



Performance

Requirements

Features

References

Cost

Address

Portable t Field Instrument

Two-channel NaI (Tl) scintillation spectrometer t photomultiplier tube t amplifier t4-decade digital readout and 5-decade meter readout for uranium surveys.Spectrum stabilized using Am2~1 59.6 keY reference.

Energy Range: 0.25 to 3.5 MeV gammas; calibrated controls (300 keY/turn)Channel Width: 0-500 keY (synunetrical expansion); (50 keY/turn)Ranges: lOOt 300 t 1000t 3000 t 104 cps

Accuracy:Temperature Range: -10°C to +60°C

Power: Eight "D" type cells (R20) with 40 hour life; or external l2V supplySize: 30 em x 11 em x 25 em (12" x 4.5" x 10")Weight: 7 kg

Two separate counting channels; plus internally preset discriminator; waterproof case; 100 mV output for strip-chart recorder. Provision for externalcontrol of one channel position t may be used with 1000 meters of standardcoaxial cable.

Developer's specifications

On application

Group Commercial OfficerAtomic Energy Research EstablishmentHarwell t Didcot t Berks t ENGLANDTel.: Abingdon 4141Telex: 83135 Cable: ArENt ABINGDON

Class

<.)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Fixed Filter Air/Iodine

Monitor-Victoreen Model 840-2

Laboratory and Power Reactor Site Monitoring

RAD-NUCIodineVictoreenNov; 1971



Sampling

Performance

Air is pumped through a charcoal filter and the iodine particulatesare counted.

From 10-12 to 10-6 ~c/cc at 4 cfmModel 843-2 Beta scintillation detectorModel 843-3 Gamma scintillation detectorModel 843-4 G-M detector

Air pump system, 4 cfm air flow, collection eff: 95%

Meter accuracy: + 2% fullscaleTime constant: 10 clm - 1 minute

106 clm - 0.2 sec.Temperature range: O°C - 50° C

Requirements Power:

Size:Weight:

110 Vac, 10 amps, 60 Hz, single phase(others available on request)114.3 em H, 61 em W, 72.5 em D (45" H, 24" W, 28.5" D)227 Kg (500 lbs)

Features

Reference

Single channel analyzer capabilities for iodine monitoring, andairborne particulate monitoring or both simultaneously; alarms foralert, high radiation flow rate, and failure, log and linear scales.


Cost

INSTRUM ENTATION

FOR ENVIRONMENTAL

MONITORING

Upon request

RAD-NUCIodineVictoreenPage 2, Nov. 1971

Address Victoreen Instrument Division10101 Woodland AvenueCleveland, Ohio 44104(216) 795-8200

843-2 Beta __

843·3 Gamma __

Background = Approx. 100 CPM @ 1 mR!hr CoGO.

1 W ~ ~ ~COUNTS PER MINUTE/MINUTE INCREASE IN COUNT RATE

System Sensitivity with Models 843-2 Beta and843-3 Gamma, Scintillation Detectors.

10-6

~~IR FLOW 4 CFM 1'= ~l2 ~

1O_12.l-LJ...LU.illL-L-Ll.LBWaccllkg_"--,Un_dLJ~...LAllPPill"'_·-"[email protected],_mRL.'hJ...r.LJC0-lJ6o.J.L.

.1 I 10 102 W3 104

COUNTS PER MINUTE/MINUTE INCREASE IN COUNT RATE

System Sensitivity with Model 843-4G-M Detector

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Scintillation Detector

Packard Model 446

Laboratory

RAD-SYSPackardNov. 1972

..~



Sampling

Performance

Requirements

Features

Cost

Address

Cylindrical sample chamber is surrounded by a 4" annulus of liquidscintillator and six 3" dia. photomultiplier tubes. The tubes aremagnetically shielded and have individual controls for fotus and gain.A lead shield surrounds the entire detector to reduce background. Ahandhold is provided to insure reproducible geometry for forearm counting.

Sensitivity:Range:

Aluminum cylinder 4.25" D, 8" L.


Power:Size: 100 cm H, 95 cm W, 79 cm D (39.5", 37.3", 31")Weight: 771 kg (about 1700 1b)

MOde1446 $7,875.Less shielding and cabinet $4,830.

Packard Instrument Co., Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 696-6000

n

--u

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Gas Proportional Counter

Packard Model 894

RAD-SYSTritium, Carbon-14PackardNov. 1972

Class Laboratory

• •.. iii ..~.. j [

)



Sampling

Performance

Requirements

Features

Cost

Address

Detects tritium or carbon-14 as they elute from a gas chromatographiccolumn using a flow-through ion-multiplication detector. A copper oxidefurnace oxidizes all organic compounds to carbon dioxide and water toeliminate sample condensation in the tube.

Sensitivity: BetasRange: 10 linear ranges, 200 cpm max.

Five-decade log scaleCounting Efficiency: 58% Tritium

80% Carbon-14

Continuous

Accuracy:Temperature: Operates at room temperature

Inlet heating to 300°CFurnace heating to 800°C

Time Constant: 2 sec

Power: 120-220 V ac (switch) 50 or 60 Hz, 720 wattsSize: 35.6 cm H, 54.6 cm W, 61 cm D (14", 21.5 ", 24")Weight: 90 kg (200 lb)

Use with Model 7401 Gas ChromatographBackground about 30 cpm (variable offset)Variable upper and lower discriminatorsSimultaneous analog and scaler outputRight or left-hand capability to couple with any G.C.

Packard Instrument Co., Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 696-6000

Class

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Liquid Scintillation Spectrometers

Packard Model 3390 and Others

Laboratory

RAD-SYSLiquid ScintillatorPackardJan. 1973



Sampling

Performance

Requirements

Liquid scintillation spectrometer system. Matched bialkali photomultipliertubes in coincidence mode detect light; pulse height analysis electronicsprovides spectrum information. Background subtraction done automatically.Automatic calibration with external source arrangement.

Sensitivity: UnknownEnergy Range: Can detect any beta, alpha, electron capture, X-ray, or

weak garruna ray isotopes.

300 sample capacity with up to 10 repetitive counts per sample or up to 10preset number of complete cycles for counting all samples. Also hasautomatic and group counting mode that allows empty samples with a group.

Accuracy: UnknownTemperature: Controlled temperature (maintained ±0.5°C over range

-5°C to +15°C) or ambient temperature

Power: 100-130 or 200-260 V ac, 50-60 Hz, 1000 VA (max)Size: Height 62-1/4 to 67-1/4", adjustable (158 to 171 em); width

4l-l/2to 57" (depending on readout device); depth 31" (79 cm)Weight: 1000 lb (450 kg)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-SYSLiquid ScintillatorPackardP~~e 2 Jan. 1972

Features 1. Three separate pulse-height analysis channels.2. Single-, double-, triple-labeled capability.3. Independent controls for nonnalizing each photomultiplier tube.4. Preset count, background subtraction, low-level reject for each sample

channel.5. Automatic external standardization with radium-226 and americium-24l

sources.6. On-line computation and display of net count rate and standard deviation.7. Gamma pUlse-height capability.8. Automatic sample oxidizers: Models 300, 305, and 306 (optional).9. Flow measurement capability using flow-cell and adapter.

10. Model 544 Absolute Activity Analyzer automatically adjusts to optimizecounting rate and background conditions and computes quench-correcteddpm for single- or double-labeled samples (optional).

11. Model 3050 extra shielding package for low-level counting (optional).12. Model 3090 Automatic Channel Selection (optional).

Models 2101,

Other Models Model 3385:

Model 3375:

Model 3330:

Model 3380:

Model 3320:Models 2425

Identical to Model 3390 except not available with Model 544Absolute Activity Analyzer.Identical to 3380 except not available with 544 AbsoluteActivity Analyzer.Similar to 3390 except does not have on-line computationfeature, one-source instead of two-source calibration system,some other differences.2111, 2211, and 2311: Have fewer features; similar to

Model 3320.Identical to Model 3390 except 200-sample capacity and notavailable with Model 3090 Automatic Channel Selection.Identical to Model 3330 except 200-sample capacity.

and 2450: Similar to Model 3390 except Servo-Tray samplechanger. Model 2425 has l50sample capacity.Model 2450 has 450-sample capacity.

References

Cost

Address


Model 3390 $17,095. Model 3330 $15,595.544 4675. 3305 8665.513 1435. 2450 14,500.545 1670. 2425 10,615.542 525. 2311 9565.

3385 16,095. 2211 7990.3380 16,595. 2111 6205.3375 15,595. 2101 5200.

Packard Instrument Company Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 969-6000

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Auto-Gamma Spectrometer

Packard 5000 Series

RAD-SYSSpectrometerPackardJan. 1973

Class



Sampling

Performance

Requirements

Features

References

Laboratory

Automatic 300 sample controlled temperature gamma~spectrometer. Twodiametrically opposed NaI(Tl) scintillation crystals, photomultipliers.Optional tandem liquid scintillation system for beta counting; Ge(Li) forhigher resolution y spectroscopy; and Si (Li) for higher resolution X-rays.Automatic background subtraction, low-level count rejection. Three .independent pulse-height analysis channels with three scalers.

Sens i tivity: UnknownEnergy Range: Unknown

300 sample capacity changer with repeat, group, and automatic countingmodes. Solid or liquid samples.

Accuracy: UnknownTemperature: Maintained within ±0.5°C or ambient operation

Power: no or 220 V ac, 50 or 60 Hz, 10 A (max)Size: 170 cm H, 105 cm W, 79 cm D (67", 41.5", 31")Weight: 680 kg (1500 Ib)

1. Preset time/preset count modes up to nine isotopes.2. Coarse and continuous calibrated fine gain adjustment.3. Digital printer output, IBM Selectric or Teletype option.


Cost Model 5320522051205385

$12,86512,36510,86515,665

Beta Model 5120-835220-835320-83

$17,90018,90019,400

Address Packard Instrument Company Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 696-6000

Ji

.,-- ,

()

oINSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

Radiochromatogram Scarmer

Packard MOdel 7201

RAD-SYSBeta ScarmerPackardNov. 1972

Class Laboratory



Sampling

Radioactivity is measured by two windowless G-M tubes arranged in 4 TI

configuration to scan both sides of the strip. Resolution between adjacentspots is controlled by two adjustable collimators.

Sensitivity: Beta emitting nuclidesRange: Ratemeter has 9 linear count ranges and log scale 102

, 10 3 ,104 ,

10 5, 10 6 , and 3 x 10 2

, 103, 104

, 10 5

Accepts chromatograms from 0.5" to 2" wide, lengths up to ISO feet, alltypes of papers up to Whatman No. 3MM

Performance Accuracy:Temperature:

Time Constants:Scarming Speed:

From 0.1 to 300 sec (8 settings)From 0.02 em/min to 200 cm/hr (16 ea.)

INSTRUMENTATION

FOR ENVIRONMENTAL

MONITORING

RAD-SYSBeta ScannerPackardPage 2 Nov. 1972

Requirements

References

Cost

Address

Power:Size: 88 cm H, 55 cm W, 48 cm D (35", 22.5", 19")Weight: 98 kg (215 1b)


MOdel 7201 $4,115With disc integrator $4,950

Packard Instnunent Co., Inc.2200 Warrenville RoadDowners Grove, IL 60515(312) 696-6000

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