Translated material
The deadline is half -life. Investigation
Who is to blame for the Chernobyl disaster, people or technology? A brake operating as a gas and a plane at an extremely low height
In the second part of the special project dedicated to the 30th anniversary of the accident at the Chernobel nuclear power plant, Radio Liberty talks about a operation of the causes of the disaster, about the charges made to the operators managing the reactor on the fatal night and the actual culprit of the explosion.
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Next part: Liquidation is not completed
At the end of August 1986, the IAEA conference was held in Vienna, to which the Soviet delegation brought an official report on the causes of the Chernobyl accident, its consequences and their liquidation. The Soviet report presented by the head of the delegation Valery Legasov formed the basis of the Insag-1 report of the International Consultative Group for Nuclear Safety (Insag). Both documents laid almost all the blame for what happened to the Chernobyl staff.
The key conclusion was formulated as follows: "The root cause of the accident was an extremely unlikely combination of violations of the order and operating regimen. The catastrophic size of the accident acquired due to the fact that the reactor was brought by the personnel in such a non -grouping state in which the influence of a positive reactivity on the growth of power was significantly intensified."
This means that the more steam is in the active zone, the higher the speed of the chain reaction, moreover, the reactor can go into mode when its power begins to grow spontaneously. It is clear that this kind of relationship is critically dangerous: the atomic reactor in no case should not unactroly heating itself, otherwise the explosion is only a matter of time. This dangerous effect is laid down in the design of the RBMC reactor-and this is also recognized in the report, but with a reservation: it becomes dangerous only because of the fatal mistakes of the operators. This can be compared with the statement that the aircraft, of course, can fall if the crew was not aware of the fuel, opened all the hatches at the height, stopped the engines, and then directed the car directly into the ground.
Not any of our document, not any of our textbooks says that our reactors can explode
After a year, already in the courtroom, it turns out that the station operators simply did not know about this dangerous effect. The indicative process began in July 1987, in a specially repaired house of culture of the city of Chernobyl. The defendants were six people: the director of the Bryukhanov station, the chief engineer Fomin, the head of the reactor workshop number 2 Kovalenko, the inspector of Gosatonnadzor Laushkin, the shift head of the Rogozhkin station and Anatoly Dyatlov. The hearing lasted 18 days, accusatory sentences were issued to all the defendants. Director Bryukhanov, chief engineer Fomin and his deputy woodpeckers received 10 years in prison, Rogozhkin, Kovalenko and Laushkin were convicted of a shorter time. We can say that the judicial board also issued one acquittal-the RBMK-1000 reactor.
Here are a few quotes from the speeches of the accused and witnesses on the process.
Court of Chernobyl Employees
Kovalenko: "Not any of our document, not any of our textbooks, is said that our reactors can explode."
Rogozhkin: "I worked for the uranium-graphite reactors for 34 years, but never, nowhere was noted that they exploded. I learned about this only in the prosecutor's office."
Dick, the head of the station change: "We did not know about the dangers of the reactor at low power in physics of the reactor ... The RBMK was designed with a retreat from nuclear security standards, the steam effect is positive. This led to the acceleration of the reactor. This should not be on all physics textbooks."
Kazachkov, former shift chief of the 4th power unit of Chernobyl nuclear power plant: “Even with the regulations, it could explode. There is a positive steam effect. [...] I believe that this type of reactor was supposed to explode sooner or later. [...] on the Smolenskaya, Kursk, maybe at the Leningrad NPP (where RBMK-1000 reactors were also used due to a high steam coefficient) The reactivity and lack of restrictions was the constant danger of the explosion. "
However, official experts objected to the court objected. One of them, by the name of Polushkin, said: "Such a reactor can be operated and safe. It is only necessary to operate correctly." Polushkin, invited as an independent specialist, was actually one of the creators of the RBMK series reactors.
Before the official recognition: not so much people are to blame for the disaster as the imperfection of the reactor design - another 6 years will pass. On the second anniversary of the disaster, Academician Legasov, who made charges against the staff at the IAEA conference, was found hanging in his Moscow apartment. New conclusions were made in the report of the USSR State Committee for Supervision of the Safe Work in Industry and Nuclear Energy, published in 1991. Two years later, they confirmed their conclusions and specified the report of the INSAG-7 IAEA advisory group. “In connection with the current perception of events, there is a need to shift the emphasis in such a way that it, to a greater extent [of the actions of personnel] concerns the shortcomings of the design funds, which was mentioned in the InSAG-1, as well as recognize the problems due to the structure under which the station was carried out,” this document says.
RBMC had two serious constructive problems. We already know about one - positive steam reactivity. The second is the end effect of absorbing rods. When they fall into the active zone, they must quickly stop the nuclear reaction. But in the case of the RBMK-1000 reactor, they were designed so that in the first few seconds of immersion, the reactor did not only slow down, but rather slightly increased reactivity in it.
The layout of the RBMK-1000 reactor, pride and symbol of safe atomic energy. At the exhibition in 1983
In 1990, an interview with Academician Anatoly Alexandrov, director of the Institute of Atomic Energy, President of the USSR Academy of Sciences and the main inspirer of Soviet atomic energy, was printed in the journal "Skonek". Answering the correspondent’s question, Alexandrov said: “Understand the reactor’s disadvantages. [...] The matter is not in the design. Do you drive the car, turn the steering wheel in the wrong direction - is the accident! Or the engine designer? Everyone will answer:“ Is the unskilled driver to blame. ”Dyatlov in his memoirs answers this statement in an emotional tone in absentia:“ You drive a car, press on the brak. Instead of braking, the car accelerates. Accident! Is the driver to blame? Or maybe, after all, a designer, a citizen of an academician? "
You drive the car, click on the brake. Instead of braking, the car accelerates. Accident! Is the driver to blame? Or maybe still a designer, a citizen of an academician?
So what actually happened to the reactor that night? According to a fairly established consensus today, the situation has developed like this. The disconnection of the emergency cooling system in the afternoon of April 25 was fully consistent with the test program and did not play role in further events. But a decrease in power from 720 to 500 MW in the first half an hour on April 26 went beyond the proposed regime. However, no regulatory documents prohibited work under such conditions, and Anatoly Dyatlov, as the deputy chief engineer of the station, had the right to independently make a decision on a new regime. A failure of power up to 30 MW when switching to manual mode is apparently really Leonid Toptunov’s mistake, but the error is quite common, as the witnesses at the trial, a failure, larger or smaller, would allow any operator.
But the next moment, the personnel made a decision, because of which, apparently, it really should bear part of the responsibility for the accident. Instead of drowning the reactor, which, according to some evidence, demanded akims and toptunes, it began to disperse it, taking out the absorbing rods from the active zone. Dyatlov wanted to conduct tests on this day, and conduct successfully. Formally, the regulations did not require stopping the reactor at low power, but from a physical point of view, it was at that moment that it began to work unstable. Firstly, the smaller the rods remain in the active zone, the more difficult it is to control the processes occurring in it. About the same as a less controlled car becomes a squeezed clutch. Secondly, dangerous physical processes began to occur in the reactor zone: the distribution of the density of the neutron flow became uneven, the so-called poisoning began in the central part of the reactor shaft-the release of gases that greatly absorb neutrons. Inexpensive sensors did not give the staff a complete picture of what was happening, and most importantly, none of the operators suggested that the reactor was in emergency mode.
How the large aircraft flying at low altitude is dangerous, the RBMK reactor at low power is so dangerous, at this level it is poorly controlled and controlled
Nikolai Carpan, deputy chief engineer of the Chernobyl nuclear and nuclear security, explained this in court as follows: “How dangerous a large aircraft flying at low altitude is, the RBMK reactor at low power is so dangerous, it is poorly controlled and controlled at this level. The reactor’s work at low capacities was not sufficiently studied. I think that the staff did not have a clear idea of the danger”. The power was brought to 200 MW and stabilize, but the reactor itself turned into a short -action mine.
A group of liquidators is preparing to reach the roof of the Chernobyl nuclear power plant reactor after the disaster on May 10, 1986
The alarm signals warning about the problems in the devices-devices actually indicated that the reactor is close to the regime in which a positive steam reactivity coefficient could lead to uncontrolled reactor power growth. This is exactly what happened with the start of the tests: the power became slow at first, and then grow faster.
Only at this moment, woodpeckers, Akimov and Toptunov finally realized that the car had lost control. And they pressed the brake-the AZ-5 emergency defense button, which drops all absorbing rods into the active zone. It seemed that this was guaranteed to drown the reactor in any situation, under any operating mode. But because of the end effect, which no one had known at the station about at the station, the “brake” worked in the first seconds as a “gas”-and this small additional jump in power turned out to be critical.
It is noteworthy that some Soviet engineers know about the end effect of absorbing rods a few years before the accident. It was discovered during the launches of the 1st unit of the Ignalin nuclear power plant in Lithuania and the 4th unit of the Chernobyl nuclear power plant back in 1983. The scientific director of the RBMK-1000 project indicated then that "when the reactor power is reduced (for example, when one turbine is turned off), the reactivity supply is reduced due to poisoning and distortion of the high-altitude field occurs. [...] A3 triggering can lead to a positive reactivity. Apparently, a more thorough analysis will reveal other dangerous situations." Recommendations were given on eliminating the dangerous end effect, but for two and a half years that passed before the Chernobyl accident, they were not only not embodied in the RBMK reactors operating in the country, but even the problem itself did not become known to the staff working for them.
The InSAG-7 report also mentions a relatively insignificant, although leading to the radioactive emissions of the accident that occurred on the RBMC reactor of the 1st block of the Leningrad NPP on November 20, 1975. Its reason was the second fundamental problem of the RBMK-1000 project-heating the reactor of himself due to the positive steam efficiency coefficient. The special commission made a corresponding conclusion, the industry Research Institute gave recommendations, but in fact, as stated in the INSAG-7 report, “the lessons were compiled mainly only to very limited changes in the design or improvements of the practice of operation. Due to the lack of communication and exchange of information [...] the personnel of the Chernobyl nuclear power plant was not known about the nature and causes of the accident in the 1st block of the block Leningrad NPP ".
General Director of the IAEA Hans Blix at the conference "Medical aspects of the Chernobyl accident" in the USSR
Perhaps the main words of the report of the INSAG-7 Magate Consulting Group do not concern the technical defects of the RBMK-1000 project and the actions of operators on the fatal night on April 26, 1986, but the general structural and even “cultural” problems in the Soviet atomic energy, inherent in the Soviet industry in general: “We can say that the accident was the result of a low security culture not only on The Chernobyl nuclear power plant, but in all Soviet design, exploiting and regulatory atomic energy organizations that existed at that time.
Sergei Mirny , who participated in the elimination of the consequences of the Chernobyl accident as commander of a platoon of radiation intelligence, says that almost everyone was sure of the absolute safety of a peaceful atom to the disaster - from specialists to ordinary people. "At the time of the explosion, I was a physical chemist by education, my military specialty was the commander of a platoon of radiation, chemical and bacteriological protection, I was assigned to the only chemical protection regiment of the Kyiv military district, it was the only such regiment to the territory of two -thirds of Ukraine, - the peaceful one says that there was a Chernobyl accident, short information was held, but this was said about this. As an ordinary emergency incident in industry, after three days, they began to find me from the military registration and enlistment office at a completely exorbitant time before the holiday, and I was amazed at work: I did not connect these two facts - that there was an accident at the Chernobyl nuclear power plant and that my mother was shattered on the phone. an accident at the nuclear power plant? " And my father and I stuck her amicably, well, like “What do you understand, it's completely safe.”
Dosimeter Igor Akimov
Perhaps the accident at the Chernobyl nuclear power plant, even to a greater extent than the beginning of my perestroika, was the real reason for the collapse of the Soviet Union
In fairness, it is worth noting that large accidents at nuclear power plants occurred not only in the Soviet Union-both before and after the Chernobyl disaster (for example, an accident at the TRIL-MILLALEND station in the USA in 1979 or an accident at the Fukushima-1 nuclear power plant in Japan in 2011). The fundamental factors of the Chernobyl tragedy are a low security culture, the use of imperfect attitudes for considerations of economic benefit and state prestige, and most importantly, the belief that a person finally curved the titanic natural forces released by him. It is unlikely that they can be called specific for the USSR, they are quite universal. But the Chernobyl disaster both in terms of radioactive pollution, and on the socio-political consequences, not only other nuclear incidents, but also any anthropogenic accidents surpassed orders. On the eve of the 20th anniversary of the Chernobyl accident, Mikhail Gorbachev wrote : “Perhaps the accident at the Chernobyl nuclear power plant, which occurred this month 20 years ago, even more than the beginning of my“ perestroika ”, was the real reason for the collapse of the Soviet Union five years later. Indeed, the Chernobyl disaster was a turning point in history: there was an era before the catastrophe and it began completely to catastrophes and began completely Another era after it. "