My ChernobylWhat’s Wrong with Nuclear Power and

How to Fix It

Aladár Stolmár

Copyright © 2008 Aladar StolmarAll rights reserved.

ISbn: 1-4392-2017-4ISbn-13: 9781439220177

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I n M e m o r i a m L a r r y H o c h r e i t e r

University Park, Pa. – Lawrence Edward Hochreiter, 67, professor of nuclear and mechanical engineering at Penn State, died Sept. 3, 2008, in State College, Pa., from a heart attack.

In 1986, as a consulting engineer for Westinghouse, he directed engineers in developing a model for the Chernobyl RBMK reactor and performed independent calculations to verify the actual Chernobyl accident sequence.

From http://www.engr.psu.edu/

C o n t e n t s

In Memoriam Larry Hochreiter ......................................................1

Contents ...................................................................................3

Introduction ..............................................................................5

Acts of God – My Preparation for Chernobyl ..........................6

Session of the Politbureau of the CPSU Central Committee on July 3, 1986 .....................................25

What Caused the Explosion of the Chernobyl Unit 4 Reactor and What Processes Led to the Disaster? ..............................28

The Causes of the Chernobyl Disaster ..................................33

The Processes Leading to the Accident .................................34

Cover-ups and Corrections for Show ...............................................38

KGB Agents in the USA ...........................................................47

Headfirst into the Wall ..............................................................48

New Nuclear Power Plants for a Brighter Future ............................53

Questions and Answers ..............................................................57

What Do I Expect? ..................................................................59

I n t r o d u c t i o n

The quote below is from Key Witness and Silent Partner, a selec-tion of Hungarian emigrant history-forming writings, which will soon be published in Hungarian. After reading the manuscript, my dear friend Denes Kiss told me to write My Chernobyl as a separate popu-lar science book to tell my story of the Chernobyl catastrophe.

An Easter dinner was also part of it. A dear lady invited me to their family dinner celebrating Easter, where she introduced me to her middle son, Mike, also a nuclear engineer working for Westinghouse. I told him my last story at the Paks Nuclear Power Plant in Hungary, of how the safety relief valves turned out to be too fast. He looked at me with surprise: “I have a simi-lar problem on my desk right now from one of the U.S. plants!” Then I told him my solution for Paks. In two weeks, he called me up and reported that it worked just fine there as well.

My wife, Ilona, had directed my attention to the reports on the Chernobyl accident. She al-ways followed the news in the world. I tried to call my friend Feri (Frank Foldvary) at the State Department, but he was traveling and could not be reached. As soon as I put the phone down, Mike called me:

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“Do you know something about Chernobyl?” he asked.

“Everything. Believe me, I know everything about Chernobyl.”

“Ali, after the safety valves, I believe you.” That was his answer. “Wait for the call of XY,” he added.

I have to list here the events that gave me the authority to say that I really knew everything about Chernobyl. It almost appears as if some-one from above was guiding me throughout the years to gain that special knowledge.

Acts of God – My Preparation for Chernobyl

I began my studies as a nuclear engineer with a Hungarian state grant in Moscow in the USSR in 1967. I was not an exceptional student. My early enthusiasm that I would be one of the first specialists in a new industry in Hungary was soon cooled off when the daughter of the min-ister of Heavy Industry told me that the Paks Nuclear Power Plant project had been delayed, indefinitely.

“You are learning a profession that you will not be able to use at home!” she teased me.

For a good card game of tarokk or bridge, we spent our mornings at the dormitory at the card tables rather than at the lectures. The practical

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courses we could not skip. The professor of neu-tron physics himself taught the practical course on neutron activation experiments. He ordered us to redo the half-life calculation because we started with different assumptions than what he taught. It was equal to about four hours of detention.

When the repeated calculations gave the same results, I kind of arrogantly said, “You see?” He admitted that he learned something from me. A few days later he knocked on my door in the dorm and invited me to go with him to the House of Engineering. I went.

I think I was the only student in the lecture hall, and I’m sure I was the only foreigner. The building was too close to the Central Com-mittee of the Communist Party of the USSR (now it is the chancellery of the president of the Russian Federation), right across the street.

All the academicians of the USSR dealing with nuclear power were there sitting up on the stage. One after the other, they presented their views on the future of the nuclear power indus-try. After each presentation, the scientists on the stage discussed the presented material and later took a few questions from the auditori-um. At that time, I liked the lecture about the TOKAMAK fusion reactor the most, but today it is clear that the most important event of the evening was the dispute over academician A. P. Aleksandrov’s lecture about his RBMK reactors

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(Reactor Bolshoi Moshnosty Kanalnyj, in Eng-lish a high-powered channel-type reactor) and how his fellow lecturers cornered him.

One after the other, all the others sitting on the stage disputed the idea presented by Tovarisch Aleksandrov. They raised questions about iso-topic composition, positive temperature, power reactivity coefficient, and the crisis of boiling, and academician A. P. Aleksandrov was used as a punching bag. Everyone else was against the building of these Chernobyl-type reactors – the infamous name they got later.

At that time, the opinion of our faculty was the following:

We are building such reactors, but we should not. They were built not by the public nuclear industry, but by the military-industrial com-plex. They were operated not by the public utility energy sector, but by the Heroic Red Army.

By chance we went for on-site practice to Belojarsk twice instead of Novo-Voroniezh (which has VVER reactors, the type planned for Paks). And in Belojarsk, the closest proto-types of RBMK were in operation. Somehow I befriended the engineer who was called in for each start-up since he could do it the best. I don’t know why, but he let me try to start up the reactor of unit two. I could not do it. Ev-ery time I switched on the steam to blow the superheater channels, the SCRAM shut down

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the reactor. (SCRAM is the sudden shutting down of a nuclear reactor, usually by rapid in-sertion of control rods, either automatically or manually by the reactor operator. It may also be called a reactor trip. It is actually an acronym for “safety control rod axe man,” the worker as-signed to insert the emergency rod on the first reactor [the Chicago Pile] in the United States [from http://www.nrc.gov/reading-rm/basic-ref/glossary/scram.html]) I wanted to know why.

He gave me his article published in an inter-nal journal about this problem. In these graph-ite-moderated, light water-cooled reactors, the water in the superheater channels is a neutron absorber. When you blow the channels, you re-place the water with steam, and it absorbs sig-nificantly less neutrons, which leads to a sudden power excursion, which triggers the reaction of safety regulators to shut down the reactor by inserting the regulator neutron absorber rods.

I asked, “Let me try it again!”

He let me try it again. I called another Hun-garian student and asked him to insert the reg-ulator rods when I told him to, and I started to blow the superheater channels with small increments, constantly watching the neutron flux indicators. Everybody enjoyed the success of the start-up, and I learned forever that the water in the graphite-moderated reactors is a neutron absorber.

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An interesting dinner and meeting resulted from this start-up. A few days later, the guy who let me start the reactor pulled up in his car next to two other Hungarian students and me and took us to dinner. We dined with a very important person, called Boris Nikolayev-ich. After a few bottles of vodka, he started to sing, and nobody could carry the tune – nobody except for me, because I had learned a large number of Russian folksongs from my Russian wife and her roommates during the time I was courting her.

So Boris Nikolayevich called me up from the end of the table to sing with him. He hugged me and dressed down the plant management when he learned that I was Hungarian, not even a citizen of some Baltic state – as he thought from my appearance – because I still knew the beautiful Russian folksongs, whereas the Russians at the plant did not. We drank a few more glasses of vodka and sang more songs – and this great friendship ended when he asked me about my favorite song and I started to sing one of the then popular gulag songs (very appropriate to the region).

The next day I found out that he was Yelt-sin, the party secretary of Sverdlovsk Region. I also found out a lot about his popularity in the Sverdlovsk area among the nonparty mem-bers as well. In general, I found him very pleas-ant during our drinking and singing. So when he received high publicity as Moscow party

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secretary in 1987, I asked my friend Feri in the State Department to invite him to the United States because he was the man of the future – he was the one who could and would transform Russia into a democracy, not Mikhail Gorbachev.

I was somewhat out of touch with Feri when they invited Yeltsin. One day I received a very upsetting call from him. “Who did you ask us to invite? This drunk went on a rampage in the U.S., touched the backsides of stewardesses on the airplanes, and generally he had too great of a time …”

“So? He is a full-blooded Russian man,” I an-swered.

It took only a few years before our Boris Niko-layevich stood up on the tank and did what I expected from him.

There were a few pipe breaks while we were on the site. They asked for our help to make some repairs because their workers had all got-ten their allowed radiation exposure doses for the month. It directed our attention to the high frequency of boiling crises in the channel-type reactors. The surface of the evaporator tubes could heat up so much under the heavily loaded fuel rings that a steam film formed when the cooling water flow-rate dropped, which caused the frequent tube breaks.

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In the course of the following year, we had a frequent visitor, an older former student. We taught him to play tarokk and bridge, and he showed us card tricks and told us of the events at the Leningrad RBMK prototype reactor start-up. I remember one of the stories he told us about an accident during a low power start-up. A piece of nylon foil left in the pipes closed the water flow of sixteen channels, causing a lo-cal power increase, a crisis in boiling, and zirco-nium-steam reaction on the surface of the fuel cladding. Exactly the same processes led to the TMI-2 and Chernobyl-4 accidents later.

Fortunately the channel tubes – also made of zirconium – did not catch on fire because the graphite moderator behind them was cold and the hydrogen that was forming pushed out the steam before the channel walls could heat up, so “merely” sixteen fuel assemblies had to be replaced. I must repeat here that the same zir-conium-steam reaction was the key process in both the TMI-2 and Chernobyl-4 accidents, but at these events nothing could stop it.

In the early spring of 1973, I returned home with a degree in nuclear engineering, and there was no sign of a nuclear power plant in Hun-gary, not even plans. The commissioner of the nuclear power plant project, Beni Szabo, asked me to work for him.

“I don’t want to shuffle papers,” I told him. “I want to create machines. I want to become

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an engineer, not only on paper. I met a guy from the university. He is a start-up engineer at ERBE the Hungarian power plant building general contractor company and told me what he was doing. I want to do something similar.”

Beni was surprised, but called up the director of ERBE and told him he was sorry that he had not thought of it earlier; indeed, the young, unemployed nuclear engineers would benefit from taking part in the installation and start-up of conventional power plants, getting some engineering practice instead of becoming paper pushers.

A number of new contacts with the RBMK reactors came from my decision to work for ERBE. The very first one was in connection with the partisan actions of MSZMP PB poten-tate Ferenc Havasi. (He was a Hungarian So-cialist Workers Party Politbureau member and friend of Janos Kadar, the most powerful person with the highest authority related to the power industry.)

The design work of the Paks Nuclear Power Plant was progressing in advanced stages. Regular meetings of the technical requirement negotiations were underway for the equipment supply contracts. This is when some Russians invited Tovarisch Havasi to the Chernobyl Nu-clear Power Plant. One of the members of the delegation told me the story of this visit right after his return and added that, indeed, the

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inviting party convinced Havasi that we in Hungary should also build a nuclear power plant like the Chernobyl in Paks.

One of the main arguments for Havasi to build RBMK reactors in the Paks Nuclear Power Plant was that the operators rode bicycles in the turbine hall and how cool that was. I be-came really nervous and called my partner in Moscow: What the heck is that? They also got very nervous. Behind our backs, or way above our heads, the intrigues and clan interests were played, so characteristic for the Communist totalitarian system. Possibly only minutes de-cided that the “highest authority’s” mandatory decision could be prevented.

As for the official letter written by Havasi that the VVER design of reactors in Paks had to be replaced with the RBMK reactor type, we could send back a copy of a short letter from the great Soviet Union’s related authority stating very briefly:

“Nyet.”

We sighed with relief and Havasi got furious. Indeed, he found out that I was the one who crossed his way.

My partner in Moscow was Jura Perekrestov, who had an uncle, Misha, whose last name was Gorbachev. At that time, Uncle Misha was a Central Committee member of CPSU and a ris-ing star. We had several conversations starting

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with the words: “Uncle Misha told me …” One of these conversations continued with words that I was very surprised by: that he thought that the Polish-Russian relationship could only be normalized after they admitted that the massacre in Katyn was done by the NKVD, predecessor of KGB, the infamous Soviet secret police …

Two of us, along with my friend Viktor Nikulin, developed the technical requirements for the design and equipment supply contracts, includ-ing all the safety aspects for the Paks Nuclear Power Plant. For guidance we used the safety (safeguard) guidelines originally compiled by Edward Teller, the famous Hungarian father of the hydrogen bomb and promoter of nuclear power, interestingly enough, based on Viktor’s request. He wanted to elevate the safety and technical level of the nuclear power plant for Paks to international standards so that it could be marketed anywhere in the world.

Viktor Nikulin was the head of the Technical Department in the Ministry of Energy and Elec-trification of the Soviet Union. Any equipment designed for any nuclear power plant could be built and installed only with his signature. One evening he took me to a faraway restaurant, and after dinner he pulled a letter from his brief-case. It was a top secret letter from the office of Brezhnev (general secretary of the Communist Party of the USSR) to Viktor’s boss, G. Sha-sharin, deputy minister. It briefly stated that

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it was nonsense that the Red Army operated the RBMK nuclear power plants and ordered the ministry to name the conditions and de-velop the schedule of the transfer into their authority.

“I want to talk about this with you,” Viktor told me.

We agreed that they could only take over the RBMK nuclear power plants into the public sector if they also conformed to the safety re-quirements we had developed for the Paks plant. Drawing on the napkins and taking notes, we went through the RBMK design. Just in our heads …

The next afternoon, Viktor took me to his of-fice and showed me the typed-up wish list for improvements of the RBMK design. It looked OK, so I agreed. We took it together to Shasha-rin. Only on this occasion did Viktor introduce me to his boss.

About three months later, Viktor told me good-bye. He had been building nuclear power plants since the age of sixteen, and now he was going on to become a director of one of the coal burning power plants. He explained why:

“Do you remember our list of required modi-fications for RBMK? Shasharin will take the power plants over without the first necessary addition on our list. Shasharin got convinced,” he said with irony.

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At the top of our list was the inclusion of reac-tors in the containment, the lack of which was the cause of releases to the environment in the Chernobyl disaster.

I had my last encounter with RBMKs after 1980. My university called me to be a consul-tant for the thesis work of a Hungarian student. He wanted to simulate the RBMK reactor’s neutron and thermo-physical characteristics on the computer. I jumped on the idea, and the boy successfully showed the positive power re-activity and the fact that in reality there were at least sixteen independent reactors in that mon-ster.

The faculty management of the university did not really like the conclusion drawn from the boy’s work that such reactors should not be built. This power reactivity coefficient meant that while in the Paks-type reactors – with neg-ative power reactivity – the pulling out of the absorber regulators results in a higher stabilized power level. On the contrary, in the RBMK reactors – with positive power reactivity co-efficient – the small pulling out of regulators has to be followed with significant insertion of regulators to reach another higher power level. This is similar to when you accelerate your car by touching the accelerator pedal and pushing hard on the brake to get the desired new higher speed …

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Briefly that was the “everything” I knew about the Chernobyl Nuclear Power Plant.

I love Hungary. I did not even want to travel abroad after my return from the Moscow uni-versity. In 1985 I had to emigrate to the United States because the circumstances around the NPP Paks forced me. We were in the process of erecting the four units of the nuclear power plant, and we had designed the process to re-turn the spent nuclear fuel back to the USSR after about five years of interim storage in the refueling ponds adjacent to the reactors, when a letter from the deputy prime minister of the USSR to the deputy prime minister of Hun-gary arrived ordering us to extend the storage of spent fuel to ten years.

Hastily a conference under the International Atomic Energy Agency (IAEA) was organized for the Communist countries’ representatives in Marianske Lazne in Czechoslovakia where the Soviet designers introduced the separate “Spent Fuel Storage” facility design to be built at each of the nuclear power plants to extend the stor-age time for ten years after its removal from the reactor. At that meeting, I became famous for questioning the authority of the Soviet deputy prime minister’s ordering of the sovereign states to increase their investment by about 20 per-cent – the estimated cost of the storage facility was almost as high as one complete 440 MW unit. Therefore, the addition of such a costly storage facility to each of the Soviet-built nu-

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clear power plants should have been introduced at the economic cooperation of socialist states COMECON’s governing body’s level.

As a response, I developed an alternative com-pact spent fuel storage solution, already com-mon in the West but never introduced in the Soviet design. Upon my return from this con-ference, I completed my development and had an opportunity to discuss the administrative requirements for its introduction in Paks with the director of the Kurchatov Institute respon-sible for Paks.

I did not get a budget for this project, but within the NPP project, I had it done anyway. For example, I approached the Voest Alpine steel giant for the boron-containing stainless steel I needed, and they made an experimental heat, a small amount of boron containing stain-less steel melted in a small electric arc furnace from their own research budget and rolled it for me as I requested. I gave it to KFKI (Central Physics Research Institute of Hungary), where the modified, proposed spent fuel storage pond structure was put together on the ZR-6 reactor to measure, test the neutron absorbing char-acteristics, and assure the subcriticality of the design. I myself performed the thermal and neu-tron physics calculations and put together the package for the Kurchatov Institute’s approval.

In about four weeks, we got the approval. It eliminated the need for the storage facility,

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which was already included in the budget as a 25 percent increase of the entire investment.

In about a year, I found a list on my desk: man-agement bonuses approved on the basis of in-vestment savings achieved at the NPP Paks. Seventeen percent of the savings was distrib-uted among the high-level managers, starting with the deputy minister of Heavy Industry of Hungary, Laszlo Kapolyi at that time. Seven-teen percent of the budget of a nuclear power plant unit is a very large amount. If they would pay the fee for the innovation – which in fact was my innovation – the MVMT (Hungarian electrical utility) would have had to pay only 7 percent.

I went to court. At the second hearing, the lawyer for the MVMT brought an order from the minister of Heavy Industry (at that time the same Laszlo Kapolyi, who was leading the list, took most of the money) ordering any court proceedings involving the nuclear power plant Paks to be secret. The lawyer of MVMT brought that letter and not the explanation re-quested by the judge. The judge requested a description of how this modification was intro-duced by the opinion of MVMT, if the MVMT disputes my claim that it is my invention. This is why I ended up in the United States at the time Chernobyl blew up. (Declaring the court proceedings secret equaled to a death threat. If someone should publish anything about my innovation dispute, the members of the

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communist maffia could sentence me to death on the basis of laws on the book at that time.)

I got the call from XY, and the following morn-ing I flew to Pittsburgh. Mike met me at the airport and took me to Westinghouse’s offices. I signed the consulting contract, then rented a car and moved into a hotel.

On May 13, 1986, I started to investigate the Chernobyl accident at Westinghouse. A few days later Larry Hochreiter took me to Wash-ington, D.C., to introduce me in the Depart-ment of Energy and at the Nuclear Regulatory Commission. Later I was assigned full-time to A. David Rossin, the assistant secretary of En-ergy for Nuclear Energy, as his adviser. I was to help him with the interpretation of the report issued by the Soviet Union about the accident and with the development of the United States’ (international community’s) position.

In addition to the publicly performed work, I felt that this disaster could be the “big push” that could result in the collapse of Commu-nism. I was in daily contact with my friend in the State Department, Feri. The responsibility of the Communist leadership in the cover-up, denying the fact of the Chernobyl-4 accident for days, was obvious. President Reagan quickly understood that this cover-up must be a sign of some really serious responsibility on the part of the Communist leadership. And I could pres-ent the details of that, with proof. Gorbachev

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took the president of the Academy of Sciences of the Soviet Union, A. P. Aleksandrov, with him to Reykjavik, giving such a clear target to President Reagan that it was impossible not to hit a bullseye.

Yes, it was possible to point the fingers. The U.S. party could list the dirty tricks and crimes showing how the Soviet totalitarian system had been used to push through the creation of Aleksandrov’s nightmarish idea. It also could be added that the faulty nuclear power plant design was not the general characterization of the Soviet science, but only where it led when totalitarianism takes over science – all in con-nection to the Chernobyl accident.

It was blackmail, indeed … We were going to publish the details explaining why these power plants with RBMK reactors were being built over the protests of Soviet scientists and engineers. The Soviet new class would see the consequences. Not even the sheepish Russian people would tolerate such obvious crimes. Only if … Only if the high Soviet leadership allowed the separation of the Baltic states and pulled its armed forces from Central Europe …

Imagine the position of Uncle Misha when he realized that the opposite side knew more about the internal Soviet fighting leading to the Cher-nobyl disaster than he did. It was meticulously hidden from Gorbachev that there had been accidents earlier, how many professionals had

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left their life-calling professions in protest, and how many academicians stood up against this design, and now the U.S. president listed these for him. When Gorbachev asked about these, it turned out that everything was exactly as Rea-gan had said. There was no time to look for a way out; the trusted advisers had lied to him, so what could be done? This U.S. president was capable of anything.

Gorbachev could not allow the United States, by publishing the facts, to churn up the Soviet nation and the world against the Communist leadership and against many members of the “new class.” He had to accept the proposed way out. The pullout of armed forces from Central Europe could be stretched for decades. The in-dependence of the Baltic states could be soft-ened to a negligible level …

“The main thing, we can avoid public humili-ation,” (I hear his explanation). “We have to cleanse the new ruling class, have to line ev-eryone up behind the new leadership. In a few years we can get rid of all the compromised in-dividuals and then we can start to go for world domination with renewed energy.” – This could be the thought process that led to the (make believe) capitulation of Gorbachev.

We, who were behind the official American del-egation, wanted that. I can’t stand aggression; even a single human life’s loss would cause seri-ous problems of conscience. We could not allow

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the collapse of Communism to take Hungarian lives again. We thought that it was already too much of a loss of Hungarian blood in the 1956 revolution against Communism. We did not want to ignite a civil war by voicing the dirty secrets behind the Chernobyl disaster. Indeed, we wanted to avoid another possibility by all means: the return of the open-armed oppres-sion, the reconstruction of the dictatorship of the proletariat with the control and oppression of any civil unrest, therefore making it impos-sible to have any democratic changes. We were happy not to have to take such risky steps.”

Thus ends the quote from the book Key Witness and Silent Partner. In the perspective of twenty-two years, the peaceful transition seems final. However, the real physical and chemical processes, the technical deficiencies leading to the Chernobyl disaster, are still in the dark. In fact, the damages to the fuel bundles in Unit 2 of the NPP Paks during the wash down were caused by the same processes, and what really pulled my plug – and forced me to write this book – was that the real causes and processes were not told here either. I can understand that in Russia a considerable fraction of electricity is still generated in RBMK-type reactors in single-loop nuclear power plants. But what is the reason for this care-fulness? Why is everybody keeping quiet in the other countries of the world? I think that we have to force the Russian Federa-tion to plan the shutdown of these unsafe nuclear power plants in the nearest future. Change them to other, acceptable nuclear power plants.

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This is the only possibility to open the road to the solution of today’s biggest problem: stopping the carbon dioxide con-centration increase in our atmosphere. It is only possible with the building of hundreds of nuclear power plants. And for that there is a must: to have the trust, the unshakable trust, of the public in nuclear power. And that cannot be gained with cover-ups, falsifications, and silence. We have to tell the real causes – show the real processes in the real accidents.

Session of the Politbureau of the CPSU Central Committee on July 3, 1986

Alla Yaroshinskaya, advisor to Boris Yeltsin, published an article in the Izvestija (a Moscow newspaper) on April 17, 1993 that contained excerpts from a top secret document, the only copy of the working record of the meeting in the title. She also concluded “Nothing could stop Aleksandrov and his colleagues on the road to Chernobyl.”

From the record:

Gorbachev: the commission looked into why the inadequate reactor was handed over to in-dustry. In the United States this type of reactor was rejected. Is that so, Comrade Legasov?

Legasov: In the United States they did not de-velop and did not use such reactors in power engineering.…

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Gorbachev: How many accidents have there been?

Brukhanov (director of Chernobyl NPP – A. Ya.): There are approximately one to two ac-cidents every year … We did not know that there was something similar in 1973 at the Leningrad NPP.

…

Gorbachev: B. A. Sidorenko writes that even after reconstruction the RBMK reactor will not meet international requirements.

Shasharin: The physics of the reactor deter-mined the scale of the accident … It is impos-sible to go on building RBMK reactors, I’m convinced of this. As far as their improvement is concerned, the expenditures for this do not justify themselves.

...

Gorbachev: But can these reactors be brought up to international requirements?

Aleksandrov: All countries with developed nuclear engineering are working on the type of reactors which are used in our country.

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As Alla Yaroshinskaya puts it: “Could the ‘expert’ on the RBMK reactor, Academician Aleksandrov, act against the ‘fa-ther’ of the RBMK reactor Academician Aleksandrov?” Valerij Legasov, in the movie Zvezda Polyn, said, “If there had been a philosophy connected with the obligatory nature of the containment of each one of the nuclear reactors, then natu-rally the RBMK in terms of its geometry as an apparatus could not have appeared.”

Exploded reactor still pouring steam and smoke

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What Caused the Explosion of the Chernobyl Unit 4 Reactor and What

Processes Led to the Disaster?

In the reactor fuel of nuclear power plants, one of the uranium isotopes splits as a result of neutron bombardment – releasing some neutrons in the process. This allows a chain reaction, and a level of neutron flux corresponds to the generated power. By regulating the neutron flux by inserting or removing neutron absorbers into the core, the reactor’s power can be regulated.

During the decay of the fission products, a series of radioac-tive isotopes is generated, and their release into the environment is dangerous, so the fuel is surrounded by a reliable casing – cladding. In order to exclude any danger from a nuclear reac-tor, usually three independent barriers are mounted between the fuel and the environment: the fuel cladding; the reactor vessel and adjacent piping and heat exchange surfaces; and fi-nally a building sized for the maximum possible pressure – the containment building.

This is where we can see the deficiency – most likely the crucial deficiency of the RBMK reactor design. Due to the enormous dimensions of the graphite-moderated, water-cooled reactor, the sizing of the entire building for the maximum pres-sure is not possible or would require immeasurably high ex-penses. Therefore, only the portion of the building housing the equipment adjacent to the reactor, but not the housing of the reactor itself, is sized for the possible maximum pressure. In fact, the pressure vessel is the wall of the zirconium fuel chan-nels penetrating the graphite moderator.

There is a secondary pressure boundary in the form of the reactor vessel. The reactor vessel is equipped with steam blow-down pipes sized for the release of a theoretical maximum flow

rate of steam entering into the moderator. The assumption for the sizing of this vessel is that only two – out of 1,661 – chan-nels can break simultaneously.

Indeed, the designers of the RBMK did not consider the very likely hydrogen release from the reaction of steam with zirconium. It is a very weak replacement for the containment, and the consequential failure of this vessel was unavoidable. This deficiency is present in all of the functioning RBMK reactor-containing nuclear power plant units and cannot be fixed by any possible means. The reactor is located outside of the containment sized for pressure, and the possible steam-gas releases inside the reactor vessel could not be vented through the available relief means. The Chernobyl-4 disaster could repeat itself in the twelve operating RBMK reactors anytime.

There are significant deficiencies in the regulation of RBMK reactors as well. Most of the corrective actions after the Cher-nobyl disaster aimed to correct these difficiencies. Usually in the power plant reactors, the possible loss of coolant leads to the cessation of chain reaction, which shuts down the reactor. In the graphite-moderated, light water-cooled RBMK reactors, the evaporation of water, or loss of water from the cooling chan-nels, will cause an increase of power. To correct this or at least reduce the effect, the designers changed the fuel enrichment and added additional neutron absorbers to the core.

Immediately prior to the accident, the following things hap-pened in the Chernobyl-4 reactor:

• Preparing for outage for refueling and repairs, the operators reduced the power.

• The dispatch center of the electrical grid ordered an in-terruption in the shutdown process and kept the reactor on a reduced power level for hours.

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• Prior to the shutdown, a mandatory safety test was scheduled to be performed. It was designed to dem-onstrate that the natural circulation was sufficient to maintain the cooling of the reactor in case of a complete blackout until the emergency diesel generators came online and the emergency water pumps were started up with diesel power. The test procedure required the shutdown of half of the circulation pumps.

The operators forgot about one special feature of the RBMK reactors: the xenon poisoning (in light water-moderated reactors, it is the iodine ditch). Operating the reactor on a lower power resulted in the neutron-absorbing isotopes generated on the pre-vious full power (mainly in central volume) not being burned to an equilibrium level. The central portion of the reactor gradually became poisoned by the accumulation of large neutron absorp-tion cross-section isotopes (xenon-135, this is where the name comes from) shutting down the chain reaction entirely.

In the meantime, on the periphery, the top and bottom to-ruses took over the generation of all the reduced power of the reactor in an ever collapsing and increasingly overloaded vol-ume. The only sign of this was the moving of the automatic neutron control rods into the highest position out of the core, performed by the automatic power control system in order to maintain the reactor’s power level. The temperatures measured at the exit of channels did not show the ratio of steam to water, only a uniform saturation temperature normal for this reactor.

The calculations performed later indicated that half of the fuel channels in the center of the reactor did not generate any heat, and half of the peripheral channels were well overloaded. Two separate lower and higher rings of collapsing toruses were generating all the power. The calculations indicated that the top regions in a number of channels were dangerously close

to the crisis in boiling (steam cooling) regime even before the shutdown of half of the recirculation pumps, which was manda-tory for the tests.

The “crisis in boiling” occurs when a film of superheated steam forms on a hot surface, isolating the surface from the boiling water. Sometimes it is called the “hot pot effect” and can be seen in the kitchen when a water droplet runs around and spits boiling water droplets on a red hot skillet.

The crisis in boiling is a very dangerous regime because the heat coming from the fuel pellets to the fuel cladding can only be transferred to the superheated steam film contacting, wash-ing it in a suddenly reduced fraction. The majority of it will heat up the cladding metal (zirconium) very rapidly to the met-al’s melting or even boiling temperature.

In the case of zirconium, we don’t even have to heat it that much. It is sufficient to reach about as low as 600°C when an autocatalytic reaction starts. This temperature is defined by the thickness of the protective oxide layer, but we always have to consider reduced thickness regions near the spacer grids, so the 600°C is realistic. The autocatalytic reaction leads to melting and burning of zirconium in the steam, generating hydrogen and zir-conium dioxide reaction products. The reaction heat is also sig-nificant, and the cladding can reach the temperature of ignition even if the heat from the fuel pellets was not sufficient for that.

We can speculate what would have happened had the op-erators not shut down the pumps. It is possible that the over-all poisoning of the reactor would have resulted in a complete shutdown, and the maximum damage being done would have been that some of the fuel cladding would have shown some discoloration. Maybe some fission products would have escaped into the environment, but these could not be viewed as extraor-dinary events at the RBMK reactors. It is unlikely that even a single channel would have been damaged. It would have easily

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looked like everything was okay, and nothing would have been farther from the truth.

We can also imagine that the crisis in boiling was so far pro-gressed that the intense reaction, the burning of zirconium in the steam, started well before the shutdown of the pumps, and the final outcome was independent from the safety system tests. At this point the question is whether the reorganization of the coolant channel flows according to the changes in resistances, and this could be modeled only with great difficulty.

If the water flow was reduced below a critical level in the pe-ripheral channels due to the steam generation, then even with-out the shutdown of the circulating pumps the Chernobyl-4 disaster could have happened. I hope this deficiency was also corrected after the accident in the other RBMK reactors. This flow reorganization also has another nickname, “organ effect,” and could be improved by adding flow resisting diaphragms and additional pumping capacity. I have to repeat that it is not clear whether this organ effect had any impact on the events during the accident/disaster in reality, but it could have.

The shutdown of the pumps in the critical moment and the subsequent reduction in the overall coolant flow rate through the reactor by itself was sufficient to trigger the film boiling and in-evitably ignite the zirconium-steam reaction burning process in the already overloaded, overheated channels on the hot fuel clad-ding portions. Calculations support the fact that even the normal oxide layer-protected fuel cladding could reach the zirconium ignition temperature in the steam within seconds, but we always have to allow for reduced, spalled, or worn-off oxide regions near the spacers that could be ignited soon after reaching 600° C.

This burning process is characterized with melting and splash-ing or even boiling of liquid zirconium. This metal-water reaction is familiar from the handling of liquid steel: the most frequent accident in steel plants, on the continuous steel-casting machines,

is the spilling of liquid steel into water. It leads to the oxidation of steel, the generation of hydrogen, and, inevitably, the formation of an explosive mixture of air and hydrogen and its explosion.

We should take a break here and separate the causes lead-ing to the accident and the resulting catastrophic dimensions it reached from the processes themselves that actually caused this catastrophe.

The Causes of the Chernobyl Disaster

The Chernobyl-4 accident was caused by the lack of the three independent barriers between the fuel and the environment. The last one, the building sized for the maximum possible pressure, did not even enclose the reactor itself. The middle one, the pressure vessel, was not independent at all because it was made of zirconium and could be ignited by the same zirco-nium cladding when that caught on fire. Although this middle barrier was surrounded by another pressure vessel – the reactor vessel itself, its sizing was inadequate. It could handle only a very small portion of the real release of steam and gases gener-ated from the zirconium’s reaction with steam.

The only existing barrier, the fuel cladding, also could not be accepted as totally independent; its functioning was not as-sured under any circumstances as is reasonable and required in all other states of the world. It was possible – physically and as the Chernobyl-4 accident shows in great amounts – to reach the regime of film boiling and get dangerously overheated without the event giving any information about it to the operators.

The best engineers of dozens of design bureaus work on the questions of how to detect the real operating conditions of a nu-clear power reactor’s fuel cladding, how to preserve its function-ality, and how to preserve it intact even during the most unlikely

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accidents. Their intention is to keep the cladding in a nondan-gerous temperature range. For these goals, expensive dedicated safety systems (three of them, making sure that hidden defi-ciencies cannot cause their failure!) implementing natural pro-cesses without any human intervention are being designed and installed in all of the nuclear power plants. Dedicated govern-ment control organizations safeguard their functionality under all circumstances, and the International Atomic Energy Agency along with the international organization of nuclear power plant operators spend considerable time investigating any deviations or damages to these in any nuclear power plant in the world.

The danger of a catastrophic accident in the RBMK nuclear power plants arises from the lack of three independent barriers between the fuel and the environment – barriers that are pres-ent at every other nuclear power plant in the world. This is the core cause of the Chernobyl-4 disaster. It was supplemented by the fact that the operators did not get any information about the overheated state of the reactor fuel cladding and therefore were not expected to have intervened to prevent the disaster.

The Processes Leading to the Accident

Let us now examine the processes leading to the disaster. First, the surfaces of the fuel cladding caught on intense fire; the reac-tion of zirconium with steam initiated the accident. The large quantities of this reaction were indicated by the sudden jump in the neutron flux caused by the replacement of water with hy-drogen in the affected coolant channels, to which the operators reacted with the manual insertion of an emergency shutdown absorber rod system. They must have detected the neutron flux increase before the cooling channel wall failures. They also reported that a jump in the steam separator drum pressure and

water level was observed. It was caused by the massive amounts of hot hydrogen generated in several channels incidentally and which must have happened before the channels ruptured.

These events were very close in time to the shutdown of the circulating pumps; therefore, it is not possible to decide whether the zirconium-steam reaction independent from the shutdown of the pumps also would have led to the disaster. It is important only from the viewpoint of the following correc-tive actions: more than likely the operators of the RBMK reac-tors had been ordered to rely on the operations of the cooling pumps even though it is possible that the Chernobyl-4 disaster would have happened even if they had not shut down these pumps. The zirconium-steam reaction, once started, could not be stopped, and the corrective actions performed may not pre-vent the occurrence of another Chernobyl-4-type disaster.

We have to list the organ effect or the self-reorganization of the coolant flows in the same category. Even if solutions are implemented to prevent this deficiency in design after the Chernobyl disaster, we cannot assure the excluding of a coolant loss from the fuel channels – meaning that the protection of the cladding in any accident, and indeed the lack of the two other necessary barriers in the RBMK-type nuclear power plants – | was not corrected. The RBMK reactors are just as unsafe now as they were before Chernobyl.

There is a deficiency in the neutron physics of these reactors: the xenon poisoning during power reduction or stoppage. It could be handled by administrative means: do not try to op-erate on reduced power and do not attempt the restart if you missed the available window.

Due to the poisoning of the central volume of the reactor core, the power generation was pushed into the peripheral channels. There the higher power generated higher amounts of steam, which in turn led to increased resistance. This reduced the coolant flow

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in the most heavily loaded channels, in turn allowing – through this organ effect – the approach to the film boiling regime.

Indeed, the replacement of water with steam by itself caused a local reactivity increase. A power increase inevitably followed, thereby exacerbating the already runaway autocatalytic reaction leading to the ignition of the fuel cladding and the start of the zirconium-steam fiery reaction on the higher elevations. It pro-gressed from the top down and attacked the channel walls, also made of zirconium. The splashing cladding fragments, consist-ing of melted droplets, ignited the channel walls, and when they weakened – also the internal pressure significantly jumped due to the generated hot hydrogen (detected even in the steam sepa-rator drum pressure and level jump) – these channels tore apart.

Actually, the start of channel failures also could trigger mas-sive failures of the adjacent channels due to their mechanical connections through the reactor’s upper structure. The flow-ing of the water, steam, and hydrogen mixture with splashing, burning zirconium metal fragment droplets (the amounts were so high that the available vents could release only a small frac-tion of the influx) into the graphite moderator volume stopped the chain reaction and pressurized the moderator volume sev-eral times higher than the design pressure, causing the rupture of the reactor vessel and the lifting of the heavy upper struc-ture. This was observed as the first explosion. At this time, the molecules of zirconium dioxide with the washed away uranium dioxide were settling out from the hydrogen gas and forming the well-publicized lava flows in the lower elevations.

Upon entering into the reactor hall, hydrogen gas mixed with the air and formed an explosive mixture that was ignited by the flying, burning zircaloy metal fragments. This was the second explosion, which destroyed the building. The air enter-ing into the reactor space fed the fire of the graphite blocks of the moderator. At this time, most of the zirconium was already

consumed in the fiery reaction prior to the channel failures and prior to the reactor vessel failure.

We recognize here in this unique catastrophe one single gov-erning process: a well-known chemical reaction of the fuel clad-ding and channel wall metal’s (zirconium alloy) fiery reaction with superheated steam.

An early experiment with clearly recognizable signs of fire of

zircaloy in steam – Courtesy of Bob Leysehttp://nuclearpowerblog.blogspot.com/

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Cover-ups and Corrections for Show

Almost 10 percent of the electricity generated in Russia comes from the eleven RBMK reactor units operated on the ter-ritory of the Russian Federation. Lithuania gets 60 percent of their electrical energy consumption from the single operating Ignalina Unit 2 1500 MW RBMK reactor. They are the record holders; in the 1990s, they generated over 80 percent of their electricity in the two RBMK units. As a condition for joining the European Union, Lithuania has already shut down Ignalina Unit 1 and will shut down the last RBMK reactor still operat-ing outside of the Russian Federation by the end of 2009.

Can we take a deep breath now? I would not – Russia plans to operate some of the units as long as 2024 according to the plans in effect. It is possible that they will implement power increases and further extensions of operations as well.

One may ask what the problem is. The problem is that a second RBMK reactor accident will make it impossible to con-tinue to operate any other nuclear power plant in the entire world – when in fact the RBMK reactor is not like any other normal reactor in the world.

This is where “my Chernobyl” starts – the compromise I took. This compromise allowed the continuation of the operation of RBMK reactors in exchange for the democratic changes in the former Soviet Union and the satellite states (East Germany, Czech Republic, Poland, Hungary, etc.) We did not attack the operation of the RBMK reactors for twenty-two years in ex-change for these democratic changes. As a result, the specifics relating to zirconium-steam reaction in other types of nucle-ar reactors could not be bluntly revealed. We had to be very careful when talking about the possibilities of a zirconium-steam reaction and its leading role in all other accidents in any other nuclear power plant. Unfortunately, it also means that the

owners of nuclear power plants won’t rush to place orders for new units until the possibility of another Chernobyl-4 disaster hangs over their heads.

During the accident of TMI-2 (Three Mile Island Nuclear Power Plant Unit 2 near Harrisburg, Pennsylvania) in 1979, our company’s contact person to the Ministry of the Interior of Hungary asked me to stay in my office overnight while a mes-senger transported the “news” from the accident and took my evaluations back to the party-government hierarchy. I spent all night there although my stay ended abruptly after I asked my contact, “Are you doing this sabotage?”

Two hours after I asked that question, they let me go. They had enough of my evaluations. At some point I surprised them with a request to tell the operators of the TMI-2 to turn back on the pump they had just turned off. Much later we discussed our stories with Edward Teller, and he told me, overwhelmed with emotions, that he had wanted to tell the operators the same thing, at exactly the same time – and he had a heart at-tack over it.

The NRC (Nuclear Regulatory Commission) organized a meeting in Washington, D.C., about the Chernobyl-4 accident in May 1986. Larry Hochreiter from Westinghouse (later he was a professor at Penn State) took me there. I was showing off how well informed I was about the latest Russian news and called the attention of the participants to the similarity of the intense, fiery zirconium reaction with steam both in the TMI-2 and Chernobyl-4 severe accidents. Harold Denton, presiding over the meeting, stood up before I even finished and took off running from the meeting room. He did not return, and they never called me to the NRC again. They only listened to me in the Department of Energy (DOE).

Years later I learned that Harold Denton had been the per-sonal envoy to the TMI-2 accident site during the accident and

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that he had been dispatched by President Carter himself. He was the one calling the shots – what I described as sabotage – in the control room of TMI-2. In 1986 he held the position of director of Reactor Safety in the NRC, and later he became the director of Government Affairs.

At Westinghouse – thanks to my friend Larry – I gained access to all the documents related to the TMI-2 accident, in-cluding the video freshly taken in 1986 inside the reactor ves-sel to evaluate the situation for the removal of debris from the reactor vessel. Also at that time, the Severe Fuel Damage (SFD) tests were finished in one of the reactors – Power Burst Facility (PBF) – in the Idaho National Engineering Laboratory (INEL), and the reports were issued about them.

I also have to mention another report. The Hartford Reserva-tion, Pacific National Laboratory (PNL), issued a report that graphite cannot be ignited because it does not burn. The re-searchers at PNL directed a torch onto the top of a graphite block, and the flame from the torch was licking the top surface of the graphite block and could not ignite it. Larry and I, with-in minutes, could present calculations based on the graphite’s heat conduction and the ratio of surface areas heated and not heated resulting in the observed phenomenon that the graphite block could not be ignited under these conditions.

It was shocking to see that the specialists dealing with nucle-ar power did not understand physics. They would rather believe their eyes and conclude that it was not the graphite that was burning in Chernobyl simply because they could not ignite it in Hartford.

Indeed, there was a good reason why the Hartford guys de-signed this experiment and issued this report. When David Rossin, the assistant secretary of Energy for Nuclear Energy, asked the auditorium in the situation room of DOE whether there were any reactors in the United States similar to the

RBMK or Chernobyl type, only I answered that there was one in Hartford, the N reactor.

Only after my response did the U.S. specialists – mostly connected to the situation room through telecommunications – admit this similarity. The N reactor is very similar – only the channels are horizontal, not vertical. The assistant secretary ordered the N reactor’s immediate shutdown, which was done. That hurt the people in Hartford, and the graphite report was how they tried to answer it – or attempted to reverse the deci-sion with this strange research project.

In relation to the Chernobyl-4 catastrophe, the activities di-rected to silence and cover up the real causes of the TMI-2 ac-cident had decisive significance. I see the core cause of today’s intolerable situation that the RBMK-type reactors are still operating exactly in that coverup of the cause of TMI-2 acci-dent. What really did happen at the Three Mile Island Unit 2 near Harrisburg? One of the safety relief valves stuck open, and through that the primary coolant leaked out. The operators (and President Carter’s personal envoy, Harold Denton, who then arrived on the site) shut down the make-up water pumps, which were feeding water into the primary circuit. They did that because they were relying on the level indication of the pressurizer vessel and because they were afraid to overpressur-ize the mistakenly perceived “full” system and wanted to avoid breaking it.

However, at the same time, all of the thermocouples lo-cated on the exit of fuel bundles above the core indicated temperatures well above saturation, corresponding to that pressure. This would indicate to anyone that there was steam in the core; moreover, it was superheated steam. It ruled out the chance of being solid – filled with liquid – and there was no danger of overpressurization and breaking the reactor vessel or pipes.

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On the other hand, the level detector they relied on was a simple differential manometer. The reference side was con-nected to a standpipe located near the pressurizer, and it was kept full by condensing the steam entering into it from the top of the pressurizer. Because the stuck-open relief valve released from the top of the pressurizer where the reference pipe also was connected, the pressure decrease could boil off the water in it together with the pressurizer vessel itself. The equal level on the two sides of the differential manometer read “full” for the pressurizer level. In fact, the indication that the level was ris-ing was generated by the fact that the pressurizer was already empty and the reference water was boiling out. An empty or steam-filled pressurizer and steam-filled, empty reference pipe also read “full” on the pressurizer level indicator. They took the reading of the coincidental boiloff of the water from both the pressurizer and the reference pipe to mean that the system always was full of water, when in fact only the possibility to detect the level was impeded.

We have to understand that the operators were relying on the pressurizer level reading, which they were trained to do. That was the most important indication for them during the unit start-up operations. That was also written in the manufacturer’s operating manual. What I cannot understand is how the head specialist trusted by the president of the United States (himself a nuclear engineer) disregarded the indications of several ther-mocouples (which simply could not indicate anything other than what really was there) that there was superheated steam in the higher elevations of the core. Unquestionably! It had to be clear that the primary circuit was leaking water (coolant) from the reactivity indications, and the two together must have led to the reevaluation of the single level indication’s reliability.

Instead they waited until the water boiled off from the spac-es between the fuel rods in the core, and the burning of the

zircaloy cladding with the superheated steam caused a “massive core relocation event” before they restarted the make-up water injection. This is a very intense burning process that produces extremely hot hydrogen gas that rises in very intense flows, be-ing the lightest gas. Due to the action of these intense jet flows, the end caps of the fuel rods – made of stainless steel – became projectiles and were shot into the upper plate, holding the core and the fuel bundles down. These end caps in great numbers were welded into the bottom side of the upper plenum. Indeed, these intense jet flows churned and grinded the fuel pellets themselves as well.

The generation of hydrogen has a positive result (if it is done in a closed space): it will fill up the higher elevations very quickly and push down the steam, feeding the fire of the zir-conium, which in turn extinguishes the fire. At the same time, hydrogen has a high heat conductivity and will cool off very quickly, meaning it will shrink and allow the flow of steam to reenter into the higher elevations where the still hot clad-ding tube and bundle wall plate zircaloy metal fragments are located that still did not burn off. This is an unmistakable (un-less someone wants to misinterpret it) sign of the real chemical processes, the burning of zirconium in steam: multiple ignition and intense burning with pressure spikes and cessations of the burning process with quick depressurization.

We have to remember the other reaction product besides hy-drogen – zirconium dioxide or zirconia. This will fly with hy-drogen gas in a fine (molecular) powder form, and when it falls out, it will most likely meet a surface of water. That water will evaporate and a hard ceramic, porous mass will be formed. In-deed, the churned-up, fragmented, and melted-on-the-surfaces ceramic fuel pellets will be enclosed in that hard precipitation, which will show a porous structure due to the boiloff of water. Anyone in his right mind would expect that when such hard

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structures are found in a severe accident post-mortem investi-gation or in the tests performed to investigate such severe ac-cidents, or the reconstructed measurements during an accident or test show such multiple ignitions and fire extinguishings in the form of pressure spikes – that there had been a zirconium-steam fiery reaction.

Unfortunately, even after the Paks Unit 2 refueling pond ac-cident, it did not happen that way. And it really would have been very simple. The operators stopped the cooling pump when there were quite hot fuel bundles with high residual de-cay heat in the washing vessel. These heated up so significantly during an entire night that the upper portions of the fuel bundles became covered with superheated steam. A fiery zirco-nium-steam reaction started, and although these processes are well known and all the signs were there, the accident had to be explained with something else. Why? I don’t know the answer to this question. I also don’t know who else, besides the Russian RBMK reactor operators and maybe Harold Denton, would be interested in covering up the zirconium-steam reaction.

In my opinion, we the nuclear engineering community should proudly pronounce that we know that the zirconium-steam reaction was the governing process in all nuclear power plant severe accidents and the tests performed to simulate these. We know exactly how we ended up at the dangerous operating conditions, and we installed the means in our nuclear power plants that will protect us from getting into such situ-ation, ever. (Indeed, the RBMK reactors have to be taken out of service!)

The INEL SFD test series started with a Scoping Test, which showed the multiple ignitions exactly as they occurred in the TMI-2 and Chernobyl-4; even the effects of the hot hydrogen jets could be clearly identified on the channel wall, saturated with hydrogen. As a typical reaction to the results, the NRC,

which was financing the tests, ordered the researchers to talk about something else, and when I objected, they answered with exactly this kind of report with such explanations – almost like the above mentioned “graphite could not be ignited.”

All the following Severe Fuel Damage (SFD) tests were per-formed with greatly reduced coolant (steam) flows, much below the real flow rates in the TMI-2 accident. Only the Scoping Test had an uncontrolled, realistic steam flow, and its results perfectly simulated the accident progressions both in the TMI-2 and later Chernobyl-4’s severe accidents, but nobody wanted to recognize it. The one who saw it had to be silenced by nam-ing this test “scoping” (eerily similar to the Paks fuel washing “results”).

On the left is a picture of a typical test bundle worked over by zirconium fire in the steam.

Lanning et al. reported:

TEST RESULTS

Following the uncovering and dryout during the coolant boilaway, the rods heated at a rate of 2 to 5 K/s until peak cladding temperatures of 1700° K were attained, at which time the au-tocatalytic oxidation reaction resulted in a tem-perature excursion (at a rate of 10 to 50° K/s) and hydrogen generation. Peak local cladding temperatures are estimated to have exceeded 2600° K, based on information from thermo-couples on the outside of the bundle liner.

The high-temperature oxidation reaction began at the 2.4- to 3.04-m elevation and formed a localized burn front that moved quickly down

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ward as far as the 1.2-m elevation and then steadily upward. The burn front reached the top end caps (3.80m) and ceased 15 min. before the end of the test. The oxidation reaction con-sumed 75% of the total zircaloy or almost 100% of the zircaloy in the path of the burn front. The remain-ing 25% of the zircaloy was always below or near the bundle water level. The amount of hydrogen generated was 300±30 g, close to the total conversion of the 1.26-g/s make-up coolant flow within the 45-min. high-temperature period. The hy-drogen flow fluctuated during the 45-min. high-temperature period in response to similar fluctuations (10% to 20% relative) in the bundle cool-ant flow. The peak hydrogen flow was 190 mg/s, which corresponded to an oxidation power of 28 kW.

FULL-LENGTH HIGH- TEMPERATURESEVERE FUEL DAMAGE TEST #5D. D. LanningN. J. LombardoW. K. HensleyD. E. FitzsimmonsJ. K. Hartwell @ EG&G-IdahoF. E. PaniskoApril 1988 – Completion Date

September 1993 – Publication DatePrepared for U.S. Nuclear Regulatory Commis-sionUnder U.S. Department of EnergyContract DE-ACO6-76RLO1830PNL – 6540

cited at http://www.osti.gov/energycitations/product.biblio.jsp?query_id=2&page=0&osti_id=10188341

With description: “Post-test visual examination of one side of the fuel bundle revealed no massive relocation and flow block-age; however, rundown of molten cladding was evident.” This contradicts the above description of authors that the cladding burned off above the water level with a rate allowed by water flow – a very typical misrepresentation regarding zircaloy fires.

KGB Agents in the USA

I was already at Westinghouse working on the consulting contract for the Chernobyl-4 accident investigation ordered by the Department of Energy (DOE), when someone from the CIA called me up and said that he wanted to meet me. I was not happy to hear that; back in Moscow, I had already learned that the CIA was filled with double agents affiliated with the KGB, and I knew that the CIA was not allowed to work inside the United States.

I called my friend Frank Foldvary in the State Department, and he agreed to hold this meeting at his house to check this guy out. We had no problem with this young American kid. He connected me with an older man who jokingly introduced himself as Herby. He was a very energetic man who wanted to talk me into testifying before Congress that the operators of the nuclear power plants in the Soviet Union were being forced to

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work in a high-dose radiation environment and that was what led to the Chernobyl disaster. I refused, so his entire day’s effort to convince me went down the drain. Years later I recognized Herby as robert hanssen – that FBI-KGB superspy about whom a movie was also made not that long ago.

I kept in contact with the young CIA guy, and I always checked with Feri as to what I could say to him. Through him we also tried to pressure the Soviet Union to present a report about an internal event before the international community – for the first time in the history of the Soviet Union – to force the issue of the Vienna report about the Chernobyl disaster.

During the preparations to the Vienna meeting, another CIA agent came to our conference in the DOE. The employees of the Energy Department told me that he was a spook. He was a very strong character, and with extremely efficient power talk, he was able to twist out a different plan of action from what I proposed. I had the opportunity to recognize him much ear-lier than Herby: he was Aldrich hazen Ames, a double agent whose arrest was the biggest scandal in the history of the CIA.

I’m surprised that despite the use of such KGB big guns against me, I survived and am still standing up on my feet. What did Ames succeed to invalidate from my ideas? The forc-ing of the Soviet Union to give us a timetable for the shutdown of all the remaining RBMK reactors.

Headfirst into the Wall

I did not really plan it that way, but it turned out that way. After the investigation of the Chernobyl disaster ended, West-inghouse hired me as a probabilistic risk assessment engineer first for the investigations of the Kansai Nuclear Power Plant in Japan, then investigating the Caorso Italian plant and a number

of U.S. plants. I was also involved with the advanced pressur-ized water reactor design AP-600, which began at that time.

The practice with the use, modification, and writing of com-puter codes led to the recognition of misrepresentation of the zirconium-steam reaction in these codes used to analyze severe nuclear power plant accidents. It was perfect timing because the NRC at that time ordered the installation of catalytic hy-drogen recombiners on the high points inside the reactor build-ings – containments – to handle the hydrogen generated in the steam-zirconium reaction as a response to the TMI-2 and Chernobyl-4 accidents. It was designed to avoid the explosion of the hydrogen-air mixture – for the low hydrogen genera-tion rates had been incorrectly defined in the severe accident modeling codes. I recognized that the TMI-2 and Chernobyl-4 accidents and the SFD ST test indicated unquestionably very high hydrogen generation rates that the proposed recombiners would handle by actually igniting the explosion.

The guys in the NRC were not listening to my arguments, so I had to put in an official Safety Concern. At this time, West-inghouse bought the company that developed the code, so my efforts to achieve real safety in nuclear power plants were in conflict with the company’s interests. I ran headfirst into the wall.

It did not count that the PBF SFD ST, the very first severe fuel damage test, performed in Idaho, proved my interpretation clearly (when they let the coolant enter as it did in TMI-2 to feed the zirconium reaction with steam). The video taken inside the TMI-2 reactor core, which showed clearly the work of hy-drogen jets with very high temperature, was also disregarded, and the last argument that was disregarded was that Soviet sci-entists clearly described the effects of the hot hydrogen jets in the Chernobyl-4 accident.

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The NRC, for good money, always found volunteers to write reports about nonsense like “steam explosion” or core meltdown – all impossible and easily denied on the basis of elementary school physics and chemistry processes – just to cover up the mistakes made by the NRC. There were even willing “profes-sionals” to deny the zirconium-steam reaction as the leading process in the nuclear power plant reactor core accidents – even falsifying test results. And as the report of the Paks Unit 2 re-fueling pond accident shows, that is still where we stand today, twenty years later.

I went to work in the steel industry twenty years ago. I wrote a correct steel solidification modeling program, the basis for which I used my earlier zirconium-steam reaction thermal cal-culation program. This allowed me to design the steel quality into the steel continuous casting machines. I travelled the world with that design work, and during my flights I saw the chang-es: that there were no more glaciers in the Alps in October, how greatly they were reduced in size in the Andes, what chunks of the Arctic ice were replaced now by clear water. Today I follow the change of the atmospheric carbon dioxide, and it upsets me that the public falls for the lies that the ethanol produced from corn releases less carbon dioxide into the atmosphere than the fuel from oil – when in fact it releases more.

There is a very simple solution: if every country would have at least 80 percent of its electricity generated in nuclear power plants, then the atmospheric carbon dioxide concentration in-crease would stop. An equilibrium of carbon dioxide concen-tration in the air is achievable. Indeed, for that the Russian Federation has to take responsibility and phase out the RBMK reactors. I know: I’m running into the wall headfirst again.

Now, twenty-two years after the Chernobyl disaster, one can find such statements on the Internet as “the real causes may

never be known” (by the way, Harold Denton included these exact words in one of his presentations about the TMI-2 acci-dent, signaling the end of the zirconium-steam reaction research funding). After that, usually some large bluff follows about the “steam explosion” starting with a make-believe fragmentation of the ceramic fuel. After the TMI-2 accident, the fashionable bluff was “core meltdown” or “China Syndrome” (The impos-sible idea that the ceramic fuel is melting and flowing down toward China came from a quite good Jane Fonda movie called The China Syndrome). The agents for the coal-mining interests anti-nukes were reiterating this “bluff” until the removal of fuel from the reactor showed that there had never been melted fuel flowing down.

I have to criticize the professionalism of the profession-als again. The “core meltdown” theory that was so loudly ad-vertised after the TMI-2 accident had to be taken seriously. Therefore, I performed a calculation to simulate such a core meltdown process for the VVER-440 reactor of NPP Paks. Assuming the highest possible residual heat generation and adding all of the heat from the reaction of available zirconium with steam (which is by itself impossible because this heat is transported away by the hydrogen generated and the molecules of zirconium dioxide), I melted some mass of fuel and let it go down toward China.

The first barrier on its way was the support plate of the core with drilled passage holes for the coolant. I could pass through this by limiting the thickness of melted away steel and by switching off the cooling of any medium, gas or steam. In fact, when the TMI-2 reactor was taken apart, there was a homoge-neous zirconium-uranium dioxide mass, most likely deposited from the gaseous phase, and some fine, loose debris on top of that. Every fuel bundle’s lower part could be removed from the

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support plate, and there was no sign of molten ceramic material melting the steel lower ends of the bundles.

But returning to my model calculation, as soon as my theo-retical molten mass dripped into the reactor vessel bottom, it froze. The heat of fusion could not melt the steel vessel; that heat was conducted away easily. No molten phase could be pre-served for any considerable time even after the water was com-pletely lost from the area. The natural circulation of air outside the vessel transferred away the heat to the surrounding struc-tures, and it indeed could not “melt through” the vessel.

Even if the water is completely lost from the primary system, the gases or even just the outside air can keep it cooled. The steel mixed into the molten mass increases the conductivity of the mix so that it cannot remain molten anymore.

At the same time, in a real zirconium-steam reaction-gov-erned accident, only about 10 percent (in normal reactors, not the RBMK) of the fuel pellet surface is melted away, washed away by the hot hydrogen jets (hydrogen mixed with the other reaction product, zirconium dioxide and the washed away fuel molecules, uranium dioxide) in molecular form. The fact that only a fraction of the fission products are released even in such a severe accident as the Chernobyl-4 disaster should cause some serious thinking for the proponents of these make-believe pro-cesses as “steam explosion” and “core meltdown.”

The “steam explosion” theory appeared so ridiculous as an explanation for reactor accidents that when it was first intro-duced at an international meeting at Dulles Airport about the Chernobyl-4 accident, both Larry and I simply cast it aside. Unfortunately, we missed the moment when somehow the NRC managed to push forth this nonsense. The inventor of the idea showed the photographs of some fuel pellets clearly dam-aged by hot hydrogen jets. He claimed that it was a result of “steam explosion.” We asked about the timeline, and he could

not give any believable explanation for interpreting the effects of hot hydrogen jets as effects of fuel “fragmentations.” In fact, he reversed the sequence of events from the zircaloy burning in the steam and washing the fuel away by the hot hydrogen jets to the reverse, the fuel fragmenting and – what?

He really could not say anything about how the cladding dis-appeared and how the dynamics would work because the fission products need time to transform their energy into heat inside the pellets, and the ceramic pellets need time to fragment. On the other hand, the film boiling leads to cladding burning in an instant. There were only signs of the hot hydrogen reaction product’s jet flows.

We could not expect anyone to be so stupid that after that they would still continue to repeat it. But they did – with the NRC’s funding. Indeed, there is still no mechanism that could lead to a fragmentation prior to the ignition of the fuel clad-ding. Nevertheless, you can see this stupidity even on a French Web page dealing with nuclear power.

New Nuclear Power Plants for a Brighter Future

The manufacturers, owners, and operators of the nuclear power plants have to regain the trust of the general public.

The great Soviet Union, or today the Russian Federation, already had their return on the RBMK nuclear power plants; they profited from the victims of the Chernobyl disaster. Russia took identifiable profits from the sale of oil and gas resulting in the increase of carbon dioxide concentration in the atmosphere like never seen before. Russia can even make a profit from the sale of new nuclear power plants, but they have to stop the op-eration of the RBMKs in the foreseeable future. And until they

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are shut down, these have to be operated under strict interna-tional control. Any concern about the operation of any of them shall result in an immediate shutdown of all eleven of them.

The nuclear engineers and scientists have to stop making compromises in their expert opinions following the financing organizations’ requests. They have to clearly identify the key zirconium-steam reaction in the causes of severe nuclear power plant accidents, including the spent fuel storage or refueling pond accidents (like Paks 2) and in the tests performed (INEL PBF SFD).

Today there is a strange situation in that, both economically and legally, the most capable country to build nuclear power plants is China. The most capable manufacturer of the heavy nuclear power plant equipment is South Korea. Even France, whose electricity is mostly produced in nuclear power plants (75 percent), is capable of building new plants only with the help of foreign suppliers. This situation requires a long-term international stability. There is no real ground for international

conflicts when cooperation on a global scale is required for building national economies with the use of nuclear power. And a large number of nuclear power plants have to be erected in the shortest possible time if we want to reduce the carbon dioxide emission.

During my work within the COMECON on the distribution of manufacturing of VVER-1000 nuclear power plant compo-nents between the Communist countries and later during the work on the AP-600 design at Westinghouse, I formulated the principle that we have to design the natural processes into nuclear plant systems in order to bring them into a safe shut-down condition from any possible accidental situation. This should be done in such a manner that the fuel cladding would never exceed the safe operating temperature. And even though it would exclude the possibility of a zirconium-steam reaction, we still have to have the two other barriers just in case of a deliberate hostile attack or sabotage or for the loss of integrity of the fuel cladding due to some unforeseen processes. Here indeed we should remember Edward Teller’s favored nuclear power plant design: put it into the ground, making it pretty hard to attack in there.

There is much talk about alternative energy, green energy, and renewable energy resources. In the field of nuclear power, today’s favorite is the pebble bed high-temperature gas-cooled reactor, and many see the future with the development of fusion reactors. Let’s stay on the ground! Today there is only one exist-ing, well-established system for electricity generation capable of the massive replacement of all fossil power plants: building a large number of nuclear power plants.

There are three types available on the market: (1) the heavy wa-ter-moderated channel reactor CANDU developed in Canada – despite its similarity to RBMK, the presence of cold heavy wa-ter in large quantities in the reactor makes it impossible for

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the zirconium-water reaction to progress in it even if it would ignite; (2) The single loop boiling water reactor BWR sup-plied by General Electric; (3) The two-loop pressurized water-moderated water-cooled reactor PWR initially developed by Westinghouse for nuclear submarines and supplied by several vendors. This is marketed by France as EPR, sold by Russia as the VVER 1000, and the AP 1000 designed by Westing-house (the number indicating the electrical power generated in a single unit in megawatts, MW).

Most of the nuclear power plants operating in the world to-day have such PWR reactors. The four VVER 440 reactors op-erated in Paks are also PWR, and the two 1000 MW new units hopefully soon installed in Paks will also be PWRs, either from France or Russia.

Today we live in an exciting time when the world’s politi-cal events have a defining effect on the price of nuclear reactor fuel. It is commonly known that during the cold war years, enormous inventories of nuclear weapon materials – highly en-riched uranium and plutonium – were piled up on both sides, in the Soviet Union and in the United States of America. The destruction (reduction) of these inventories was the subject of numerous intergovernment contracts, which are in effect to-day.

Also, during the production of nuclear weapons, large inven-tories of high- or medium-enrichment nuclear fission materials were collected that are not suited for use in the weapons. These all can be reworked into nuclear power plant fuel, and we have to rework them in order to achieve their final destruction as weapons. The experimental burning of such fuels in all three of the prospective nuclear power plant reactors has been ac-complished successfully. The technology is ready for mass pro-duction and use. Only the nuclear power plants still have to

be built to take this fuel and convert it to electricity in these enormous amounts. We can double the benefit from that: we eliminate the dangerous inventories of already declared useless nuclear weapons and stop the increase of carbon dioxide con-centration in the atmosphere.

I envision the future as follows: in the next centuries people will generate electricity necessary for common good living in nuclear power plants of designs already established today. After the nuclear fission materials piled up for weapons are used up, the mining of uranium ore will restart (there are considerable inventories of good quality uranium ores in Hun-gary as well), and our children will use the easily accessible uranium from the oceans as a by-product of drinking water production.

It is also possible that thorium will be added to the nuclear power plant fuels, which would result in unlimited resources, and we did not even talk about the fast breeder reactors that are operational. At least one successful example in operation is in Russia, the BN-600 in Belojarsk. It is also possible that – in combination with the fission nuclear power plants – a suc-cessful fusion reactor will be developed in a few hundred years.

Questions and Answers

What happens to the spent fuel? We have to find a place where it can be safely deposited by being buried for a long, long time. We have to base our actions on the assumption that hu-man civilization is permanent and capable of survival. We will leave the spent fuel and the radioactive nuclear waste to our children as part of their inheritance.

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Can we be assured in the unquestionable safety of nuclear power plants? We have to evaluate each nuclear power plant relative to the exclusion of zirconium-steam (or cladding metal-steam) reaction in any circumstances. In general, the BWR and PWR (VVER) type nuclear power plants include the uninter-rupted flow of natural processes in their design, ensuring that from any initial accidental situation the safe shutdown condi-tion is achieved as an end state without even getting close to a film boiling regime, potentially causing the zirconium-steam reaction. However, we have to take extreme caution when eval-uating such measures.

From my experience in Westinghouse, I have to cite here a mistake made by some young titans: they used high-pressure nitrogen gas to inject the emergency cooling water from the ac-cumulator tanks and forgot about the adiabatic cooling of the nitrogen as the pressure decreases. It would cause an ice layer to form on the check valve closing element and injection of ni-trogen gas into the reactor, which is the exact opposite of what it was designed for.

We have to demand the involvement of independent profes-sionals in the review process of the design solutions, and we must demand the freedom of information to the public about any incidents and design deficiency findings. Also, it is abso-lutely necessary to eliminate any financial interest from the scientific community and the possibility of manipulations of results of research through financing. It is time to create an independent public fund to use absolutely independently from any government agency or equipment supplier, just in the in-terest of the general public to finance independent research. It will end the very uncomfortable situation that resulted in the covering up of the real key character of cladding-steam chemi-cal reaction in the catastrophic nuclear power plant accidents.

This cover-up has led to the continued operation of the unsafe RBMK reactors for almost twenty-five years after the disaster at Chernobyl.

What Do I Expect?

I expect a thank-you note from Vladimir Putin with the timetable of RBMK shutdowns. As a token of his appreciation, he should include the cassettes of my Free Europe/Freedom ra-dio interviews.

A somewhat longer explanation is needed as to what I’m talking about. On the first year anniversary of the Vienna Report about the Chernobyl accident, my friend Ja-nos Drabik from Munich came over to us in Pittsburgh to record an interview for Radio Free Europe. He spent a week with us, and we talked about the good old times in Moscow, where he was the company lawyer and I was the technical expert during negotiations of Paks NPP design and supply contracts.

In 1980, when he immigrated to the United States, he also invited me to come with him, but I refused, saying that there were possibilities of democratic changes in Hungary and I would make a run for it at home.

When I had the opportunity to meet Frank Foldvary in the State Department, he first lectured me about the impossibil-ity of my situation – until I mentioned the name of my friend I was looking for. He lifted the phone and dialed. With the words “I give you someone,” he gave me the phone, and there was my friend Janos. It turned out that he took Frank’s place in Munich at the Free Europe Radio Station, and they were good friends.

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During the weeklong visit in Pittsburgh, I told Janos how good it felt to receive the Russian report given to the interna-tional community about the Chernobyl accident. One copy was taken by a fighter jet, refueled in the air, to Andrews Air Force Base, and a messenger brought it to Germantown and handed it to me in the gates of DOE.

I also told him the story that Assistant Secretary Rossin wanted to take me to Vienna, and it took Feri to have one of his bosses in the State Department to call the secretary to explain that it would be taken by the Soviets as a provocation, and it must be enough to keep a close contact on the phone. In fact, I was sitting back in the DOE in the USA. This was why I was waiting for the report in Germantown.

The week went by with very little sleep and lots of talk – but not a single word on the recorder. Sunday was the day of his departure back to Munich, and my wife played the organ in the Hungarian St. Ann church. We went down to the church hall and started to talk. We did not even mention Chernobyl, but talked about the possibilities of changing the totalitarian system, the centralized economy of Communist countries, into a market economy.

About a week later, Janos called to inform me that the in-terview turned out just fine – actually two one-hour interviews translated for every broadcasted language – and he made a copy for me that he would mail that day. And ten minutes later he called me again: the cassettes had disappeared from his desk, from his office, from the Free Europe/Freedom radio station’s headquarters in Munich, West Germany.

At that time Vladimir Putin was the station chief in Dresden, East Germany, running the KGB operations against the Free Europe/Freedom radio station. So, I want my cassettes back!

Aladar Stolmar is one of the first Hungarian nuclear engineers edu-cated in Moscow, USSR. During the Paks Nuclear Power Plant design and equipment supply contract negotiations, he, along with Soviet partners, developed the revised – and applied to new Soviet-built VVER nuclear power plants – safety standards corresponding to the international nuclear power plant safety standards. In conec-tion to this effort, he participated

in a failed attempt – never before published – to apply the same standards to the Chernobyl-type nuclear power plants with RBMK reactors in the Soviet Union. In 1985, when the Hun-garian court proceedings related to Nuclear Power Plant Paks were declared secret, he emigrated to the United States. Aladar participated in the U.S. Department of Energy’s effort to force the Soviet Union to report – for the first time in its history reporting about an internal event – to the international com-munity about the Chernobyl disaster. This book is his personal account of the technical issues he dealt with and the historical events he has been part of.