CHECK VALVES AGING ASSESSMENT CONF-9103142--1-Vugraphs

H. D. Haynes D E 9 1 0 0 9 6 2 9

Oak Ridge National Laboratory*

Summary

Check valves are used throughout many nuclear plant systems. Theirfailures have resulted in significant maintenance efforts and, onoccasion, have resulted in water hammer, overpressurization of low-pressure systems and dammage to other flow system components. Thesefailures have largely been attributed to severe degradation ofinternal parts (e.g., hinge pins, hinge arms, discs, and disc nutpins) resulting from instability (flutter) of check valve discsunder normal plant operating conditions. Present surveillancerequirements for nuclear power plant check valves have beeninadequate for timely detection and trending of such degradationbecause neither the flutter nor the resulting wear can be detectedprior to failure. Consequently, the U. S. Nuclear RegulatoryCommission (NRC) has had a continuing strong interest in resolvingcheck valve problems.

In support of the NRC Nuclear Plant Aging Research (NPAR) program,the Oak Ridge National Laboratory (ORNL) has carried out anassessment of several check valve diagnostic monitoring methods, inparticular, those based on measurements of acoustic emission,ultrasonics, and magnetic flux. The evaluations have focussed on thecapabilities of each method to provide information useful indetermining check valve aging and service wear effects, check valvefailures, and undesirable operating modes.

This paper describes the benefits and limitations associated witheach method and includes recent laboratory and field test data,including data obtained from the vendors who recently participatedin a comprehensive series of tests directed by a nuclear industryusers group.

In addition, as part of the ORNL Advanced Diagnostic EngineeringResearch and Development Center (ADEC), two novel nonintrusivemonitoring methods were developed that provide several uniquecapabilities. These methods, based on external ac- and dc-magneticmonitoring are also described.

None of the examined methods could, by themselves, monitor both theinstantaneous position and motion of check valve internals and valveleakage; however, the combination of acoustic emission monitoringwith one of the other methods provides the means to determine vitalcheck valve operational information.

"Tha submmad manutcupl has beanauthorad by a contractor ol tha U.S.Govarmant undar contract No D€-AC05-64OR21400. Accordngly. tha U S .Govarnmant ratama a noneidutnra.royattyfraa acanaa to pubkth or raproducaiha pubajnad lorm o) trw contrfcufan. oratow othars lo do >o. (or U S Govarranantpurpoaas."

Research Sponsored by the Office of Nuclear RegulatoryResearch, U. S. Nuclear Regulatory Commission under InteragencyAgreement DOE 1886-8082-8B with the U. S. Department of Energy undercontract No. DE-AC05-84OR21400 with Martin Marietta Energy Systems,Inc.

DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED

DISCLAIMER

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This report was prepared as an account of work sponsored by an agency of the United StatesGovernment. Neither the United States Government nor any agency thereof, nor any of theiremployees, makes any warranty, express or implied, or assumes any legal liability or responsi-bility for the accuracy, completeness, or usefulness of any information, apparatus, product, orprocess disclosed, or represents that its use would not infringe privately owned rights. Refer-ence herein to any specific commercial product, process, or service by trade name, trademark,manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom-mendation, or favoring by the United States Government or any agency thereof. The viewsand opinions of authors expressed herein do not necessarily state or reflect those of theUnited States Government or any agency thereof.

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INTEREST IN CHECK VALVES CONTINUES TO BE HIGH

. CHECK VALVES ARE USED THROUGHOUT .MANY NUCLEAR PLANT SYSTEMS

• PRESENT TESTING REQUIREMENTS FOR NUCLEAR PLANT CHECK VALVES AREINADEQUATE FOR TIMELY DETECTION AND TRENDING OF DEGRADATION

ASM17. BOILER ANDPRESSURE VESSEL CODE

SECTION XISUBSECTION IWV

ASME/ANSI OM-1987OPERATION AND MAINTENANCE

OF NUCLEAR POWER PLANTSPART 10

ASME OM CODE-1990CODE FOR OPERATION ANDMAINTENANCE OF NUCLEAR

POWER PLANTSSUBSECTION ISTC

VERIFY THAT THE VALVE OBTURATOR WILL TRAVEL TO THE POSITION REQUIRED TO FULFILL ITS FUNCTION

10 CFR SO APPENDIX J -• MEASURE SEAT LEAKAGE

• ASME WORKING GROUP OM-22 WAS FORMED TO DEVELOP A NEW STANDARDFOR CHECK VALVES -- DISASSEMBLY AND INSPECTION, NON-INTRUSIVE EXAMINATION

• MANY NOTICES. BULLETINS, AND REPORTS HAVE BEEN ISSUED THAT IDENTIFYCHECK VALVE PROBLEMS AND RECOMMEND COURSES OF ACTION

• A UTILITY CHECK VALVE GROUP WAS FORMED AND DIRECTED TESTS OFCOMMERCIALLY AVAILABLE CHECK VALVE MONITORING SYSTEMS

• EXISTING MONITORING METHODS HAVE IMPROVED AND PROMISING NEWTECHNIQUES WERE IDENTIFIED AND TESTED

THE NRC HAS HAD A CONTINUING INTEREST INIDENTIFYING AND SOLVING CHECK VALVE PROBLEMS

TITLES OF SELECTED NRC/IE INFORMATION NOTICES

NO. TITLE

90-79 FAILURES OF MAIN STEAM ISOLATION CHECK VALVES RESULTING IN DISC SEPARATION

90-03 MALFUNCTION OF BORG-WARNER BOLTED BONNET CHECK VALVES CAUSED BY FAILURE OF THESWING ARM

89-62 MALFUNCTION OF BORG-WARNER PRESSURE SEAL BONNET CHECK VALVES CAUSED BY VERTICALMISALIGNMENT OF DISC

88-85 BROKEN RETAINING BLOCK STUDS ON ANCHOR DARLING CHECK VALVES

88-70 CHECK VALVE INSERVICE TESTING PROGRAM DEFICIENCIES

86-09 FAILURE OF CHECK AND STOP CHECK VALVES SUBJECTED TO LOW FLOW CONDITIONS

86-01 FAILURE OF MAIN FEEDWATER CHECK VALVES CAUSES LOSS OF FEEDWATER SYSTEM INTEGRITYAND WATER-HAMMER DAMAGE

COMMON MODE FAILURE OF MAIN STEAM ISOLATION NONRETURN CHECK VALVES

82-35 FAILURE OF THREE CHECK VALVES ON HIGH PRESSURE INJECTION LINES TO PASS FLOW

82-26 RCIC AND HPCI TURBINE EXHAUST CHECK VALVE FAILURES

82-20 CHECK VALVE PROBLEMS

82-08 CHECK VALVE FAILURES ON DIESEL GENERATOR ENGINE COOLING SYSTEMS

81-35 CHECK VALVE FAILURES

81-30 VELAN SWING CHECK VALVES

80-41 FAILURE OF SWING CHECK VALVE IN THE DECAY HEAT REMOVAL SYSTEM AT DAVIS-BESSE UNITNO. 1

TITLES OF SELECTED NRC/IE BULLETINS

NO. TITLE

89-02 STRESS CORROSION CRACKING OF HIGH HARDNESS TYPE 410 STAINLESS STEEL INTERNALPRELOADED BOLTING IN ANCHOR DARLING MODEL S350W SWING CHECK VALVES OR VALVES OFSIMILAR DESIGN

8S-01 STEAM BINDING OF AUXILIARY FEEDWATER PUMPS

83-03 CHECK VALVE FAILURES IN RAW WATER COOLING SYSTEMS OF DIESEL GENERATORS

80-01 OPERABILITY OF AUTOMATIC DEPRESSURIZATION SYSTEM IADS) VALVE PNEUMATIC SUPPLY

CHECK VALVE FAILURES HAVE LARGELY BEEN ATTRIBUTED TO SEVEREDEGRADATION OF INTERNAL PARTS (E.G., HINGE PINS, HINGE ARMS, DISCSAND DISC NUT PINS) RESUL TING FROM INSTABILITY OF CHECK VAL VES

UNDER NORMAL PLANT OPERATING CONDITIONS

CHECK VALVE ISSUES HAVE BEEN ADDRESSED INSEVERAL NOTABLE DOCUMENTS

1985 NRC NUREG/CR-4302. VOL.1 AGING AND SERVICE WEAR OF CHECK VALVES USEDIN ENGINEERED SAFETY-FEATURE SYSTEMS OFNUCLEAR POWER PLANTS(NPAR PHASE I ASSESSMENT)

1986 NRC NUREG-1190 LOSS OF POWER AND WATER HAMMER EVENT ATSAN ONOFRE, UNIT 1, ON NOVEMBER 21, 1985

1986 INPO SOER 86-03 CHECK VALVE FAILURES OR DEGRADATION

1988 EPRI NP-5479 APPLICATION GUIDELINES FOR CHECK VALVESIN NUCLEAR POWER PLANTS

1989 NRC GENERIC LETTER 89-04 GUIDANCE ON DEVELOPING ACCEPTABLE INSERVICETESTING PROGRAMS

ORNL HAS ACTIVELY FOLLOWED THE ACTIVITIES OFTHE NUCLEAR INDUSTRY CHECK VALVE GROUP (NIC)

INCLUDING THE RECENT TEST PROGRAM

PARTICIPATING VENDOR SYSTEM NAME METHOD(S) EMPLOYEDHENZE-MOyATS, INC.

LIBERTY TECHNOLOGYCENTER, INC.

CANUS CORPORATION

CHECKMATE

QUICKCHECK

VALVE INSPECTIONPROGRAM (VIP)

ULTRASONIC INSPECTIONACOUSTIC EMISSION

ACOUSTIC EMISSIONMAGNETIC FLUX

ACOUSTIC EMISSION

• TEST SITE : UTAH WA TER RESEARCH LABORA TORY

UTAH STATE UNIVERSITY

• TESTS BEGAN LA TE JANUARY, 1990 AND ENDED IN MID-MARCH, 1990

• ORNL VISITED TEST SITE ON FEBRUARY 20, 1990• TESTS WERE CARRIED OUT ON 11 DIFFERENT CHECK VALVES IN 'NEW

AND 'DEGRADED' CONDITIONS USING WATER AS THE PROCESS FLUID

• TEST DATA OBTAINED FROM THE DIAGNOSTIC SYSTEM VENDORS DIRECTLYSHOW THAT EACH MONITORING TECHNIQUE HAS IMPROVED DURING THELAST YEAR (DIAGNOSTIC CAPABILITY AND FIELD PRACTICALITY)

AS PART OF THE NUCLEAR PLANT AGING RESEARCH (NPAR)PROGRAM, SEVERAL CHECK VALVE MONITORING METHODS

HAVE BEEN EVALUATED BY ORNL INCLUDING :

• ACOUSTIC EMISSION (ACOUSTIC SIGNATURE ANALYSIS)

• ULTRASONIC INSPECTION

• MAGNETIC FLUX SIGNATURE ANALYSIS (MFSA)

AS PART OF THE ORNL ADVANCED DIAGNOSTIC ENGINEERINGRAD CENTER (ADEC), TWO NOVEL NONINTRUSIVE CHECK

VALVE MONITORING METHODS WERE DEVELOPED AND TESTED

• EXTERNAL AC MAGNETIC EXCITATION

• EXTERNAL DC MAGNETIC EXCITATION

EVALUATIONS HAVE FOCUSED ON DETERMINING THE CAPABILITY OF EACH METHODTO PROVIDE DIAGNOSTIC INFORMATION USEFUL IN DETERMINING CHECK VALVEAGING AND SERVICE WEAR EFFECTS (DEGRADATION), CHECK VALVE FAILURES,

AND UNDESIRABLE OPERATING MODES

ACOUSTIC EMISSION TECHNIQUES HAVE BEEN USED FOR SEVERALYEARS TO DETECT CHECK VALVE IMPACTS AS WELL AS FLOW

SYSTEM SCHEMATIC

IJ

COLD LEG ACCUMULATOR

MOTOR-OPERATED VALVEf* (STROKE TIME - 1 0 SECONDS)

FM

CYCLE TEST OF A TEN INCHCOLD LEG ACCUMULATORDISCHARGE CHECK VALVEBY DUKE POWER COMPANYIN MARCH 1984

MONfTORED CHECK VALVETO REACTOR VESSEL

J- COLD LEG

THROTTLING NOISEACOUSTIC EMISSION SIGNATURE

<U)\

CLOSURE-*-

; i l - l . b i : ;FLOW NOISE-

• V < ! '

TiME- -20 (s)-

RECENTLY DEVELOPED ACOUSTIC EMISSION TECHNIQUES USEMULTIPLE SENSORS (E.G., ACCELEROMETERS) INSTALLED ON

THE CHECK VALVE AT VARIOUS LOCATIONS

DISPLAYVOLTAGE

A CCELEROMETER

DIGITALAUDIOTAPE

RECORDER(CHARGE AMPS.SIGNAL CONDITIONING)

FOREACHSENSOR

BY USING SEVERAL ACCELEROMETERS, CANUS CORPORATIONWAS ABLE TO DETECT HINGE PIN WEAR* IN A 2 4-INCH

TILTING DISC CHECK VALVE DURING THE NIC TESTS

WITH INDUCED FLOW TURBULANCE

• — -:-,-• -;-H" !-H ! ' ! I '•-'.".-'"] ^Op.n Stop Risht

' T * * . '""~r^.~r".'',"*»""YT*^~j • • i H l n g a P i n R i g h t

. P. I'mi-t--— > -Hing. Pin L.Ftd I t

A HAfiD IMPACT WAS OBSERVED ON Th£ LEFT SIDE OF Th£ HiNGEPIN BUT WAS NOT SEEN ON THE RIGHT SIDE OF THE HINGE PIN

WITHOUT INDUCED FLOW TURBULANCE

Op.n Stop Right .... ... . ...'„._ 4-i--

r*tlc Rlnj-»t Sidi

Fin

n>. .-•» Right - •--rr-r.-Tcr^-rn

Hlng. Pin Left, -'-"l" ] H T T i i I

AN IRRA TIC RINGING WAS OBSERVED ON Th£ RIGHT SIDE OF THEHINGE PIN RA Th£R THAN THE CLEAR RINGING SEEN ON Tie LEFTSIDE OF THE HINGE PIN

'15% DIAN^TER REDUCTION

AN ULTRASONIC INSPECTION SYSTEM CAN BE USEDTO MONITOR CHECK VALVE POSITION AND MOTION

SIMPLIFIED DEPICTION OFTHE CHECKMATE™ SYSTEM

SIMPLIFIED DEPICTION OFTHE CHECKMATE™!I SYSTEM*

ULTRASONICTRANSDUCER

ULTRASONICTRANSDUCER

ULTRASONIC PU-SEGBsERATOR/WSPLAY

\ ULTRASONICm i l LTRANSDUCER

(PULSE-ECHO)

DIGITALOSCILLOSCOPE

ULTRASONIC SIGNALGENERATOR-ANALYZER

CON/PUTER-BASEDSIGNAL ANALYZER

.TMTHE CHECKMATE II SYSTEM WAS DEVELOPED IN ORDER TO SIMPLIFY

THE ACQUISITION AND ANAL YSIS OF CHECK VAL VE SIGNA TURES

* DEVELOPED BY HENZE-MOVA TS, INC.

. T O ,

THE CHECKMATE II SYSTEM WAS ALSO SUCCESSFULLYDEMONSTRATED AT THE NIC TESTS

ULTRASONIC TRANSDUCER INSTALLED NEAK THE TOP Of THE VALVE

ULTRASONIC TRANSDUCER INSTALLED NEAR THE BOTTOM OF THE VALVE

14

14

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12.42

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10.803

10.300

3.795

t 9-592

8.7S7

B.2B4

7.778

7.275,

FULL CLOSED

TTT

FULL OPEN1.23 2.49 3.68 4.Si 6.14 7.33 Sr;ss

THE OECKMATE II SYSTEM COULD DISTINGUISHBETWEEN DISC FLUTTER IN MID-STROKE ANDFLUTTER NEAR THE VALVE BACKSTOP (INCL.

TAPPING) OF A 10-INCH SWING CHECK VALVE

THE CHECKMATE II SYSTEM WAS USED TO TRACKDISC MOTION OF A 12-INCH TILTING DISCCHECK VALVE FROM THE FULL OPEN TO

THE FULL CLOSED POSITION

IN 1988 , ORNL IDENTIFIED AND INVESTIGATED A NOVELCHECK VALVE MONITORING TECHNIQUE BASED ON

MAGNETIC FLUX SIGNATURE ANALYSIS (MFSA)

— DISPLAYVOLTAGE

HALL-EFFECTSENSOR

ID

m

ela

tiv<

rength

(r

d S

tietic

Fie

l

I

O.6OO.5O

O.4O

O.3O

O.2O

O.1O

O.OO

-O.1O

O.6O

O.6O

O.4O

O3O

O.2O

O.1O

O.OO

-O.1O

FLUTTER M4ONITUX

STARTED - LOW FLOW(^SUFFICIENT TO OPEN VALVE

8 1O 12 14 16 18 2O

Time (s)

OISC ON BACKSTOP

PLMP STARTED - HIGH FLOW(OPENS VALVE FULLY)

5 8 1O 12 14 16 18 2O

Tim© (s)

RECENT EXPERIMENTS CARRIED OUT AT ORNL HAVESHOWN THAT MFSA TECHNIQUES CAN BE USED

TO DETECT HINGE PIN WEAR

0.70 r

0.60

<jj 0.50%

I 0.40(0

I 0-30> 0.20

0.10

SMALL PIN INSTALLED(MORE SCATTER DUETO INCREASED HINGE

ARM ROCKING)

0.00 ^0.00

VALVECLOSED <,

'f*

NORMAL PININSTALLED

• (MINIMUM SCATTER)

0.10 0.20 0.30 0.40 Check Valve (top view)

X Gaussmeter

MAGNETIC FLUX TIME WAVEFORMS AREAFFECTED BY HINGE PIN WEAR

Normal hinge pin

030

020

0.10

O L O O

-a 10

Closed

•Pump Started

SO 40 60 80

Tin» (s)

Medium worn hinge pin

« O30

1 O 2 0

O 4 0

Severely worn hinge pin

FullOpen"

Full ClosedPump Started

TJ

I0 0 0 J Full closed

— Pump Started

40 «0 00

Tim* <s)

100 120 20 40 so ao

Time <*)

ACOUSTIC EMISSION, ULTRASONIC INSPECTION, AND MAGNETICFLUX SIGNATURE ANALYSIS METHODS PROVIDE DIFFERENT

(AND COMPLIMENTARY) DIAGNOSTIC INFORMATION

SELECTED DIAGNOSTIC CAPABILITIES AND LIMITATIONS OF THREE CHECK VALVE MONITORING METHODS

METHOD

ACOUSTICEMISSION

ULTRASONICINSPECTION

MFSA

DETECTSVALVEINTERNALLEAKAGE

YES

NO

NO

DETECTSINTERNALIMPACTS

YES

YES(INDIRECTLY)

YES(INDIRECTLY)

DETECTSFLUTTERING(NOIMPACTS)

NO

YES

YES

NONINTRUSWE

YES

YES

NO - REQUIRESINITIALINSTALLATIONOF PERMANENTMAGNET INSIDETHE VALVE

SENSITIVITY TOAMBIENTCONDITIONS

SENSITIVE TOEXTERNALLY-GENERATEDNOISE/VIBRATION

UNKNOWN

SENSITIVE TONEARBY EXTERNALMAGNETIC FIELDS(E.G.. FROMMOTORS)

MONITORS DISCposmoNTHROUGHOUTTHE FULL RANGEOF DISC TRAVEL

NO

NOT IN ALLCASES - DUE TOLIMITED VIEWINGANGLE OFTRANSDUCER

YES

WORKSWITHALLFLUIDS

YES

NO

YES

THIS TABLE DOES NOT REFLECT OTHER ATTRIBUTES SUCH AS COST. EASE OF USE, ETC.

THE SIMULTANEOUS USE OF MFSA AND ACOUSTICEMISSION WAS DEMONSTRATED BY ORNL ON A

CHECK VALVE WHOSE DISC WAS MOVEDMANUALLY IN VARIOUS WAYS

0.80

0.60

0.40

050

0.00

-050

-0.40

-O.6O

-0.80

cD

• EF

VALVE OPENS} SLOWLYMO-STROKE R-UTTERNG(HNGE AFM ROTATINGON HUGE P»J)VALVE CLOSED SLOWLYTAPPING ON SEATTAFPN3 ON BACKSTOPhiNGE ARM nOCKNSON HT40E

10 15 20 25

Time (s)

30 35 40

0.40

O.3O

0.20

0.10

o.oo

-0.1010 15 20 25 30 35

Time (s)

40

A COMBINED MFSA AND ACOUSTIC EMISSIONSYSTEM IS NOW COMMERCIALLY AVAILABLE

TMA SIMPLIFIED DEPICTION OF THE QUICKCHECK SYSTEM

DUAL SEN3OR(ACOUSTICMAGNETIC)

BA8E

MAGNET

SIGNALCONDITIONING

DIGITALAUDIOTAPE

RECORDER

COMPUTERBASEDSIGNAL

ANALYZER . DISPLAY'VOLTAGE

• DEVELOPED BY LIBERTY TECHNOLOGY CENTER. INC.

THE QUICKCHECK SYSTEM WAS ABLE TO DETECT ASIMULATED WORN" HINGE PIN IN A 12-INCH TILTING

DISC CHECK VALVE DURING THE NIC TESTS(EXPANDED SCALES TO SHOW VALVE SEATING TRANSIENT)

CHECK VALVE IN "NEW" CONDITION CHECK VALVE IN "DEGRADED" CONDITION

MULTIPLEIMPACTS

TIME >

*• 3O% DIM/ETER RECXJCTION

TIME >

AS PART OF THE ORNL ADVANCED DIAGNOSTIC ENGINEERING R&DCENTER, TWO NEW NONINTRUSIVE CHECK VALVE MONITORINGMETHODS WERE DEVELOPED THAT ARE BASED ON THE USE

OF EXTERNAL MAGNETIC FIELDS

AC MAGNETIC FIELDS DC MAGNETIC FIELDSHALL-EFFECTPROBE

PERMANB4TMAQNET -

TCMMMTTBtCO*.

VARIABLE FREQUENCYCURRENT SOURCE

SIGNALCONOITIONtNQELECTRONICS

> DISPLAY. VOLTAOE

DISPLAY __VOLTAQE —

THE EXTERNAL AC MAGNETIC FIELD TECHNIQUE WAS USED TOMONITOR THE POSITION AND MOTION OF A 3-INCH SWINGCHECK VALVE INSTALLED IN A FLOW LOOP AT OAK RIDGE

TO

a

0.50 P -

0.40 -

0.10 -

0.00 -

-0.10

FULL OPEN

PARTIAL OPENAND FLUTTERING

- - FULL CLOSED

| r 1

20 40 60 80 100 120 140 160 180

Time (s)

THE EXTERNAL DC MAGNETIC FIELD TECHNIQUE WAS USED TOMONITOR THE POSITION AND MOTION OF A PUMP DISCHARGE

SWING CHECK VALVE IN A FLOW SYSTEM AT OAK RIDGE

Signal

Valve further open(but still fluttering)due to one parallelpump stopped

Valve partially openand fluttering(pump started with 2parallel pumps also on)

Valve closed(pump off)

Pump started

Valve full open(with little flutter)

Discharge valve forsecond parallel pumpthrottled to increaseflow through monitoredvalve (note less fluttering)

Time

CONCLUSIONS

IN SUPPORT OF THE NUCLEAR PLANT AGING RESEARCH (NPAR) PROGRAMAND THE ORNL ADVANCED DIAGNOSTIC ENGINEERING RAD CENTER (ADEC),

SEVERAL CHECK VALVE MONITORING METHODS WERE EVALUATED :

• ACOUSTIC EMISSION (ACOUSTIC SIGNATURE ANALYSIS)

» ULTRASONIC INSPECTION

• MAGNETIC FLUX SIGNATURE ANALYSIS (MFSA)

• EXTERNAL AC AND DC MAGNETIC EXCITATION

• NONE OF THESE METHODS, BY THEMSELVES, COULD MONITOR THE POSITIONAND MOTION OF VALVE INTERNALS AND VALVE LEAKAGE

• THE COMBINATION OF ACOUSTIC EMISSION WITH EITHER OF THE OTHERMETHODS CAN PROVIDE THE MEANS OF DETERMINING! VITAL CHECKVALVE OPERATIONAL INFORMATION

• ALL METHODS CONTINUE TO IMPROVE A3 A RESULT OF FURTHER TESTINGAND EVALUATION

« DUE TO THE SIGNIFICANCE OF THE DATA OBTAINED DURING THE NIC CHECKVALVE TESTS AN? ITS IMPACT ON DETERMINING CHECK VALVE OPERATIONALREADINESS, IT IS RECOMMENDED THAT A COMPREHENSIVE REVIEW ANDASSESSMENT OF THE NIC TEST RESULTS BE CARRIED OUT BY NBC AFTERNIC ISSUES THEIR FINAL REPORT

STA TUS

THE CHECK VALVE AGING ASSESSMENT HAS BEEN COMPLETEDAND HAS PRODUCED SEVERAL DOCUMENTS

• 1989 WATER REACTOR SAFETY INFORMATION MEETING PAPER'Evaluation of Check valve Monitoring Methods'

(To be published in the journal of Nuclear Engineering and Design)

• 1990 WATER REACTOR SAFETY INFORMATION MEETING PAPER

'Recent Improvements In Check Valve Monitoring Methods '

• NUREG/CR-4302 VOLUME 2 (in press)

'Aging and Service Wear of Check Valves used In EngineeredSafety-Feature Systems of Nuclear Power Plants— Aging Assessments and Monitoring Method Evaluations'

FUTURE

ORNL PLANS TO STUDY CHECK VALVE ISSUES ASSOCIATEDWITH THE ADVANCED LIGHT WATER REACTOR (ALWR)

DESIGNS (E.G., BUILT-IN DIAGNOSTICS)