The accident at the Chernobyl nuclear power plant changed hundreds of thousands of destinies, caused enormous economic damage and a crushing blow to the nuclear industry, but these are only the obvious consequences of the disaster, and there are others, the echoes of which are still felt by the world community.
Impact of the accident on the development of the nuclear industry.
The 1986 disaster showed all the weak points of nuclear energy. The lack of specifics shook up the world community, causing a wave of protest, and while scientists were trying to understand everything and find the reasons, in the countries of the former Soviet Union the design was stopped and the construction of new nuclear power plants and reactors was frozen. The same situation developed in Western Europe and North America, where not a single nuclear power plant was built in 16 years, due to the fact that the resonance of opinions provoked a significant jump in insurance premiums and a drop in profitability.
Legislative consequences
The post-accident situation with the concealment of the real scale and consequences of the disaster prompted the government to adopt relevant laws. Thus, criminal liability appeared for deliberately concealing the consequences of man-made disasters (Article 237 of the Criminal Code) and mentions that information of an environmental, meteorological, sanitary-epidemiological, demographic nature, information about emergency incidents, etc. cannot represent state secrets or be classified (Article 7 of the Law of the Russian Federation “On State Secrets”). Open access is necessary to ensure the safety of the population, production and other facilities (Article 10 of the Federal Law “On Information, Informatization and Information Protection”).
Environmental consequences
As a result of the reactor explosion and over the next few days, a large amount of radioactive substances were released into the atmosphere, including: cesium-137, strontium-90, iodine-131 and radioisotopes of plutonium.
- Urban ecology
Here, pollution was concentrated primarily in open areas. Streets, roadways, walls and roofs of houses, squares and parks showed background radiation much higher than its normal value. This prompted the authorities to evacuate the population from cities and settlements in an area of 30 km around the nuclear power plant, which to this day remain uninhabited.
- Ecology of agricultural land
The territories intended for sowing agricultural crops turned out to be unsuitable. A serious problem has arisen of the migration of radioactive substances through food chains and their accumulation in the human body. In connection with this, several dozen collective and state farms were closed and farms were liquidated. The agricultural sector suffered serious losses.
Over time, the concentration of radionuclides in the soil began to decrease, which is associated primarily with weathering, their penetration into deeper layers of the earth and decay, but even now a large amount of agricultural land remains unsuitable for use.
- Ecology of water
Not only the reservoirs located in close proximity to the station were polluted. Initially, radionuclides deposited onto water surfaces, but dilution greatly reduced the contamination. Considering the fact that the water concentrated mainly radionuclides with a short decay period, their content naturally decreased significantly after a few days.
As for the leaching of long-lived radionuclides from the soil, their level is close to normal and does not harm health and the environment.
- Forest ecology
The release of radioactive dust and the high degree of its absorption led to the complete destruction of coniferous trees in the 10-kilometer zone of the nuclear power plant. Deciduous trees were partially damaged. The “burnt” forest turned red. High levels of cesium-137 were found in mushrooms, berries and other forest products.
Due to the long half-life of this element, even in a generally favorable environmental situation, the forest will remain polluted for several more decades.
The medical and social consequences of the disaster at the Chernobyl nuclear power plant are reflected in detail in the article “Victims”.
It is impossible to reveal the topic (as the largest accident at a nuclear power plant) and its consequences without understanding what the entire region was like before the tragic accident. Therefore, this article should begin with the history of the Chernobyl region of the Kyiv region, or rather even with the history of the town of Chernobyl. The accident at the nuclear power plant firmly connected this city with, but the first mentions of it date back to the 15th century (in Lithuanian sources), and it has its own centuries-old history.
History of Chernobyl and its surroundings
During the period of colonization of Ukrainian lands by Polish magnates in the 16th century, a huge castle was erected in the vicinity of Chernobyl, from which only a moat has survived to this day. Chernobyl itself (as a city remote from the capital of the Polish-Lithuanian Commonwealth) was populated mainly by Jews, thanks to whom it became one of the centers of Hasidism (one of the movements of Judaism) after the settlement of the dynasty of Hasidic rabbis Menachem Tverskoy in the town. After Chernobyl became part of the Russian Empire, Ukrainian culture began to develop in the town; Chernobyl became the center of Ukrainian song in Northern Polesie. During the Nazi occupation, the city ceased to be the center of Jewish life for obvious reasons. After the end of the war in Chernobyl, a period of industrial development began. The town acquired the status of a city, and its population grew.
Thus, Chernobyl existed long before the accident at the Chernobyl nuclear power plant occurred. The city has long been associated not only with a nuclear power plant, but also as an industrial center, as well as a place for the development of Ukrainian and Jewish cultures.
Construction of the Chernobyl Nuclear Power Plant and development of the region
In 1970, the first nuclear power plant on the territory of modern Ukraine was built in the Chernobyl region, named after the leader of the world proletariat V.I. Lenin. Of course, Vladimir Ilyich had nothing to do with the Chernobyl region, and Lenin himself was unlikely to visit these places. But since the Chernobyl nuclear power plant was actually built on a vacant lot, which was not famous for either famous events or outstanding people, it is fair that the nuclear power plant, built within the framework of the nuclear energy development program of the Soviet Union, the course for which was determined by the CPSU Congress, was named after the most revered in the Soviet Union. state of man.
Ten kilometers to the nearest city is a long distance for the resettlement of power plant employees. Therefore, next to the infamous Chernobyl Nuclear Power Plant, the nuclear workers’ settlement of Pripyat was founded, which received the status of a city in 1979. The entire population of the city, which had grown in a matter of years, was employed at the nuclear power plant, or served its employees in the city. The entire city industry was aimed exclusively at meeting the needs of nuclear workers and the station. At the time of the accident, the population of Pripyat reached almost 50 thousand people.
The city of Chernobyl itself has nothing to do with the nuclear power plant, except for its territorial proximity. He lived his life for more than one century. But it was the accident at the Chernobyl nuclear power plant, connected with the city only by its territorial proximity, that made it the center of attention of the world community.
1986 accident
In 1983, the fourth power unit of the Chernobyl Nuclear Power Plant was, as they say, hastily built. A few years earlier, Soviet scientists built a nuclear power plant in Iraq, which was destroyed from the air by Israeli Air Force fighters. This attack demonstrated the absolute defenselessness of the Soviet nuclear energy industry against a surprise attack, so Soviet nuclear scientists began to think about how to provide electricity to cities and villages in the event of a surprise attack on a nuclear facility. To conduct experiments in this direction, the fourth power unit was built, which hides many shortcomings and shortcomings made during its construction.
At night, an accident at the Chernobyl nuclear power plant occurred in the fourth power unit of the power plant. During the experiments with the reactor, two powerful explosions occurred, which determined the further unenviable fate of the entire multi-thousand population of the city of Pripyat and its environs, including the city of Chernobyl. The explosion was caused by the reactor overheating, which blew off its lid and released huge amounts of radiation into the air.
Causes of the Chernobyl accident
The causes of the accident at the Chernobyl nuclear power plant are a controversial topic to this day; many versions have been put forward, both acceptable and completely fantastic. But we can identify two obvious reasons for the unfolding events at the Chernobyl nuclear power plant - political and technical.
Political reason
In the Soviet Union, there is no doubt that great attention was paid to education. Soviet universities produced highly qualified specialists in all branches of science and culture. But for career advancement it was of secondary importance; much more important was success in political training, as well as devotion to the party and its high ideals. For this reason, the position of chief engineer of the Chernobyl Nuclear Power Plant was given to an active and executive party worker, Nikolai Fomin, who was a specialist in the field of thermal power plants, but was completely ignorant of nuclear energy. He practically did not interfere in the activities of his subordinates and completely trusted his deputy Dyatlov, who was appointed to this position in the year of the accident at the Chernobyl nuclear power plant. Dyatlov was an experienced nuclear scientist, but he came to Pripyat specifically to conduct experiments with the reactor that were pleasing to the government on that fateful night. Fomin himself was sleeping peacefully in his bed at that time.
And Dyatlov, and Fomin, and the director of the Chernobyl Nuclear Power Plant had one common goal - to curry favor with their party leadership in order to climb higher on the career ladder. And Dyatlov’s subordinates, who assisted him in the operator’s room during the experiments, realizing the possible danger of the manipulations being carried out with the reactor, were afraid to disobey the orders of their immediate superiors, since dismissal threatened the nuclear workers with moving from the warm Pripyat to the much colder cities of nuclear scientists in Siberia.
Thus, one of the main reasons why the Chernobyl accident occurred was, on the one hand, the negligence of the plant’s top management, and on the other, the indecisiveness of the personnel to refuse to carry out clearly dangerous orders from management.
Technical reason
As already mentioned, on the night of the accident, an experiment was carried out at the power plant on orders from Moscow itself. The technical goal of the experiment was to completely shut down the steam turbines of the power plant and switch to power supply from generators at low reactor operating power. Thus, in theory, it is possible to avoid leakage of radiation during the bombing of a nuclear power plant, while continuing to provide electricity for some time.
To start the experiment, it was necessary to reduce the reactor power to 700 megawatts. But during the process of reduction, the reactor power dropped almost completely. According to the instructions, nuclear scientists were required to completely shut down the reactor and only then start it again. But Dyatlov wanted quick results, so he ordered his engineers to remove all the control rods from the reactor that control the power, thereby causing it to rise sharply. But shortcomings in the construction of the reactor led to the fact that the sensors on the control rods did not take temperature readings from the very bottom of the reactor, where after the rods were removed the temperature began to rise sharply.
Without knowing this, relying on instrument readings, they continued the experiment at a power of 200 megawatts (contrary to the required 700) and stopped the turbine. Under the influence of high temperatures, the water quickly evaporated, and the reactor began to overheat sharply, but the engineers learned about this too late when a worker saw with his own eyes how the steam lifted the control rods.
Realizing the danger of the situation, Dyatlov decided to proceed with an emergency reduction in reactor power. Technically, this meant simultaneous maximum immersion of all control rods. In theory, this should have led to a rapid decrease in the temperature of the reactor, but the engineers did not take into account that there is graphite at the tips of the bromine rods, which initially briefly increases the temperature of the reactor. And since the rods were lowered simultaneously, the temperature of the reactor almost instantly increased tens of times, as a result, the reactor could not withstand the pressure and exploded.
Thus, the technical causes of the accident at the Chernobyl nuclear power plant are associated with the shortcomings of the reactor during its construction, as well as with operator error and violation of regulations.
Evacuation of people and assessment of consequences
Since the accident at the Chernobyl nuclear power plant occurred at night, assessment of its consequences began only on the morning of April 27. Previously, only a few firefighters had been sent to extinguish the fire caused by the explosion. Already after a superficial analysis and measurements of the level of radiation in the air, which turned out to be more than 120 roentgens (with the norm being up to 20), the need to evacuate people became clear.
At that time, people were officially notified of the need for temporary evacuation to nearby cities in the Kyiv region. At that time no one realized the scale of what had happened. The city identified places for evacuation, where the entire city bus fleet was taken. People were evacuated quickly, so citizens were forced to leave everything they had acquired through honest labor in their homes, and much was completely prohibited from being taken out due to the danger of radiation contamination.
Since the accident at the Chernobyl nuclear power plant occurred suddenly, in one day people lost almost everything: their jobs, a roof over their heads, they developed serious health problems, and many died from radiation sickness within a few years and lost their loved ones. But the consequences of the disaster were much larger than Pripyat, and the entire Chernobyl region. Radiation went west, picking up in Belarus and Central Europe. Even Sweden complained about rising radiation levels. But not every resident of Pripyat and nearby settlements left the contaminated zone. Some residents, strongly attached to their native places, remained in their homes. These people had to experience the downside of nuclear power.
Elimination of the accident
Despite the evacuation of people, it was impossible to leave the reactor, which was emitting destructive radiation, as it was; moreover, it was completely impossible to completely stop the Chernobyl nuclear power plant immediately after the accident. Therefore, liquidation teams were formed to eliminate the consequences.
They signed up to be the liquidators of the accident at the Chernobyl nuclear power plant voluntarily. Among them were both employees of the Ministry of Emergency Situations, military personnel, including conscripts, and concerned civilians. The Soviet media broadcast about the safety and modernity of nuclear energy, insisting that it was the future. At that time, people ignorant of nuclear energy did not realize the full danger of the situation, so they willingly joined the liquidators of the accident at the Chernobyl nuclear power plant, sincerely wanting to help their compatriots.
Only later did they realize how much they had undermined their health. One of the liquidators' primary tasks was to fill up the reactor. As a result, liquidators built a sarcophagus around the reactor, which was supposed to stop the further spread of radiation and give hope that one day the Chernobyl area would once again become habitable.
The dose of radiation received by the liquidators killed many within several years. Others became disabled, requiring constant, expensive medical care. The first liquidators, immediately after their work, were sent by plane to Moscow to the Institute of Radiation Diseases, the only one at that time in the Soviet Union. Some of the liquidators who ended up in this institute were saved. The rest received state subsidies in the form of pensions and benefits, which have been preserved in independent Ukraine to this day.
Consequences of the accident for the Chernobyl region: creation of an exclusion zone
The consequences of the accident at the Chernobyl nuclear power plant were catastrophic. The entire Chernobyl district of the Kyiv region was declared uninhabitable, as a result of which it was liquidated and transferred under the jurisdiction of the Ivankovsky district of the Kyiv region. The territory of the Chernobyl region was declared an exclusion zone. Roadblocks were set up on roads leading into the zone, and the area itself was eventually fenced off to protect against looters.
There are many rumors and legends about the exclusion zone, and many alternative causes of accidents at nuclear power plants have been voiced. The Chernobyl zone has more than once been the focus of attention of writers, journalists and computer game creators. It also attracts photographers as the site of a nuclear power plant accident. Photos of such places, made in a post-apocalyptic style, attract the attention of those who care.
The theory that the Chernobyl zone contains secrets hidden by the government still exists today, despite the fact that entry controls into the zone are no longer as strict and legal tourist excursions to Chernobyl exist.
Tourists from different countries are attracted by the city of Pripyat, which is a museum city in which the Soviet era of the late eighties froze. Since then, nothing has changed in it. The forests near Chernobyl, which became pristine, became a favorite place for hunters. And ancient Chernobyl (the accident at the nuclear power plant affected it to a lesser extent) has about ten residents who have returned to their homes.
The directors were also interested in the accident at the Chernobyl nuclear power plant. The film “Moths”, shot in Ukraine in 2013, has become a true masterpiece of cinema, which allows the viewer to plunge into the world of experiences of people caught up in the cycle of events of that time.
Consequences of the accident for the whole world. Reaction of the world community
The forced evacuation led to the irretrievable loss of the authentic culture of the Chernobyl region, whose residents dispersed not only throughout the Kyiv region, but throughout the country. The Soviet Union was forced to reconsider its attitude towards nuclear energy and its widespread use. Also, some historians believe that the consequences of the accident at the Chernobyl nuclear power plant undermined the authority of the authorities in the eyes of the population.
The world, especially the capitalist, public, politicized by the Cold War, expressed a huge protest against the USSR in connection with the increase in its background radiation. Western media were full of articles about the inhumanity of the leadership of the Soviet state, that the consequences of accidents at nuclear power plants were the result of a secret experiment, which in fact was not so far from the truth. Japan spoke out especially harshly against the Soviet Union, calling Soviet scientists barbarians who could not be trusted with atomic energy. Perhaps the journalist who wrote this article reconsidered his views after the Fukushima accident.
Major accidents at nuclear power plants in the world
Although the Chernobyl disaster is considered the largest in the world, there were other equally serious incidents.
Three Mile Island accident
Seven years before the accident at the Chernobyl nuclear power plant, on March 28, 1979, a nuclear accident occurred in the United States, at the Three Mile Island power plant, which is located in At that time, this accident was considered the largest in the world. The radiation leak occurred due to a break in the pipe of the heat release unit.
Despite the scale of the accident at the nuclear power plant, state authorities did not carry out a forced evacuation, as they did not consider the accident dangerous. But children and pregnant women were still advised to temporarily leave the nearby town of Harrisburg. In fact, people left the streets close to the nuclear power plant on their own, fearing radioactive rays.
The Three Mile Island Nuclear Power Plant continued to operate and continues to operate today, being the largest American nuclear power plant.
Fukushima accident
The second place in terms of the scale of consequences (after the Chernobyl accident) is occupied by the accident at the Fukushima nuclear power plant, located in the northeastern part of Japan. The disaster occurred on March 11, 2011. As a result of a strong earthquake of magnitude 9, an 11-meter tsunami rose, the waves of which flooded the power units of Fukushima-1. This caused a failure of the reactor's cooling system and led to several hydrogen explosions in its core.
The accident at the Fukushima nuclear power plant caused a large-scale release of radiation, which is 20 times greater than its Chernobyl counterpart. About 30,000 people received radiation poisoning. Of course, only thanks to the timely reaction of the Japanese authorities and preparedness for emergency situations, it was possible to avoid the worst consequences than the accident at the Chernobyl nuclear power plant that happened in 1986. However, according to experts, it will take at least 20 years until the consequences of the accident are completely neutralized. The disaster affected not only Japan, but also the west coast of the United States, where a few days after the explosion, an increase in background radiation was also observed.
In Japan, as in the United States, no evacuation was carried out, since modern protection systems for nuclear power plants make it possible to quickly localize the source of the release and prevent the transformation of entire cities into deserted deserts. Nevertheless, Japan had to come to terms with increased levels of radiation in food, water and air in Fukushima Prefecture, in close proximity to the emergency reactor. Health standards for radiation levels for many products have been changed due to the fact that it has become impossible to adhere to them.
Undoubtedly, nuclear energy is inexpensive and promising, but the operation of nuclear power plants requires increased caution, since the causes of accidents at nuclear power plants can be the most unexpected. But even if all the requirements are met, no one guarantees that someone’s negligence or the disfavor of nature will not cause an accident. And the consequences of accidents at nuclear power plants have to be eliminated for more than one decade. Therefore, today the best minds in the world are thinking about creating powerful alternative nuclear power plants.
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Probably for all of us the word “explosion” is rarely associated with something good and positive. An explosion is destruction, the destruction of something, this is something that will not allow life to proceed along the same route. As evidence, one can cite the explosion of an atomic bomb dropped on Japanese cities. The explosion then caused enormous destruction, and the cities had to be rebuilt over the course of many years. And although much more time has passed since the Japanese disaster than since the explosion at the Chernobyl nuclear power plant, they still remember it, realizing that with an explosion, even something that has been built over many centuries can be destroyed in an instant.
No one will argue that the explosion of Hiroshima and Nagasaki was terrible. Thousands of people suffered very seriously back then. Those who were at the epicenter of the explosion died on the spot. Others died later due to radiation sickness, which haunted the residents of cities and surrounding areas for a long time.
A similar catastrophe awaited us, but on a much larger scale. This happened when there was an explosion at the Chernobyl nuclear power plant. Thirty years have already passed, but we still remember with a shudder what happened on April 26, 1986.
Once upon a time, in an area not far from Pripyat, life was in full swing. The city, one of the most promising in the USSR, used the latest technologies of that time. It seemed that nothing and no one could disrupt the planned course of this atomic giant, because it seemed indestructible. But it is impossible to predict the exact fate of certain events. The explosion at the Chernobyl nuclear power plant entailed terrible consequences that we feel to this day.
Many, many people were forced to leave their homes, hastily evacuate, throw away their usual things and many other things that were expensive. The explosion in Chernobyl caused the city of Pripyat to be completely deserted, turning into a ghost town, about which films are made and articles are written.
Probably, many of us have seen photos of the empty Pripyat - it was the one that was first devastated by the explosion in Chernobyl. When they offer an excursion to Pripyat, they also show a photograph of this neglected, scary city. The first thing we see is a Ferris wheel, abandoned high-rise buildings, abandoned schools where children once studied... Now there is nothing alive there. Dolls, broken furniture, and broken dishes are scattered where children's laughter was recently heard. All this was caused by the explosion in Chernobyl, the consequences of which we still see today.
It would seem that more than 30 years have passed. It seems to many that everything that was just a bad dream that disappeared after a sudden awakening. But the specter of the Chernobyl accident does not go away. The explosion at the Chernobyl nuclear power plant brought too catastrophic consequences. Largely because of it, the environment has deteriorated and the health of tens of thousands of people and future generations has been undermined.
The explosion at the Chernobyl nuclear power plant is called the largest nuclear disaster; it is difficult to imagine a more complex and terrible tragedy in this area. But what was the reason, who is to blame for this happening? Could this have been avoided?
The explosion of the Chernobyl nuclear power plant: a lesson for man
Operation of the nuclear power plant nearby began in 1977. At that time, this project carried great hope, since it was this power plant that supplied energy to 1/10 of the territory of the Soviet Union, which existed at that moment. An explosion at the Chernobyl nuclear power plant seemed impossible, because it was a huge structure that looked reliable and indestructible. Nothing foreshadowed that very little time would pass (less than ten years) and a real curse would fall on the world.
However, the explosion of the Chernobyl nuclear power plant occurred. It will take many lives with it, seriously harm people's health, destroy a promising economy and cause enormous damage to the entire Soviet Empire.
It must be said that the 20th century is characterized as the beginning of a new era. It was at the beginning of the 20th century that civilization began to actively develop, which made human life much easier, but at the same time, perhaps, made us lose caution somewhere. A person somewhere forgot that he cannot always influence events, and, most importantly, one small mistake can lead to a huge, irreparable tragedy. And one such example is the explosion at the Chernobyl nuclear power plant.
Chernobyl Nuclear Power Plant after the explosion
We are already accustomed to images of desolation, since each of us watched films about the Apocalypse, where entire cities were empty, when entire cities disappeared and people were forced to start life anew. We see on the screen destroyed buildings, broken things, lonely people, broken windows, empty rooms and so on. But the worst thing is that in Chernobyl this is all happening for real.
Pictures of Chernobyl after the explosion tell of desolation and horror reigning there. It has everything that is sometimes even impossible to imagine in the scariest films.
Pictures of Chernobyl after the explosion can be found in abundance on the Internet, but there are even brave souls for whom pictures are not enough, and they go there themselves. However, this is actually prohibited because it is dangerous. Of course, if you really want to see it with your own eyes, then there is always the opportunity to go there on an excursion, where you will be taken to safe places.
The date of the Chernobyl explosion is forever etched in the memory of the whole world and has become one of the most fatal moments on planet Earth, since this disaster caused the destruction of our planet. Our home suffered enormous damage from which Mother Earth still cannot recover. The date of the Chernobyl explosion is a date of mourning for flora, fauna, and indeed for all humanity.
Facts about the Chernobyl explosion that were hidden for a long time
So, the fatal explosion occurred on the night of April 25-26. The explosion at the Chernobyl nuclear power plant killed many people, and it caused criticism of the Soviet authorities from the West. April 26, 1986 became a fateful date not only for the former Soviet Union, but also for the whole world.
The most interesting thing is that it is no longer possible to name exactly the reason why all this happened. The explosion at Chernobyl is considered a consequence of the human factor, in other words, negligence and imprudence. But then in the USSR at the Chernobyl nuclear power plant they were very attentive to various details. The experiment that was carried out on the day of the tragedy was planned and there were no signs of trouble. The explosion in Chernobyl sounded like a bolt from the blue, and for many it became a horror for many years.
Let's look at those facts that were unknown for some time and were hidden for certain reasons. Perhaps these facts will help to better understand the causes of the Chernobyl tragedy. Although, again, it is still impossible to name the exact reasons, because we will not go back to the past.
Negligence of builders
There is a version that the Chernobyl Nuclear Power Plant, which was being built at an accelerated pace, even before the accident occurred, raised concerns among both experts and engineers. Already two years after the station went into operation, signals and warnings about technical flaws in the new building began to arrive. It turns out that the destruction of the Chernobyl nuclear power plant was simply inevitable, but for some reason they did not pay any attention to it. In 2006, declassified archives were found that confirmed the presence of poor-quality installation and construction work, violations of technological discipline, as well as the presence of violations of radiation safety rules. As a result of all this, five accidents and 63 equipment failures occurred at the station even before the latest emergency. The last such message is said to be dated February 1986.
Chasing results
The explosion occurred in the fourth power unit, which was brought to its design capacity three months earlier than planned. This version is also considered as the cause of the explosion in Chernobyl, which occurred on the night of April 25-26 at 1 hour 23 minutes, to be especially precise. The accident occurred while a planned experiment was being carried out. The purpose of the experiment was to study the possibility of using the inertia of the reactor to generate additional electricity in the event of an emergency shutdown of the reactor.
The experiment was to be carried out with a reactor power of 700 megawatts. But before use began, the level suddenly dropped to 30 megawatts. The operator noticed the error and tried to correct it. After some time, the power was restored, and at 1:23 a.m. the experiment continued with a power of 200 megawatts. After just a few seconds, the power began to increase rapidly. Reacting to what was not happening, the operator pressed the emergency protection button, but for a number of reasons it did not work.
A little later, after studying all the facts, it is precisely actions of this nature that will be considered as the cause of the explosion in Chernobyl. However, they also claim that these actions were completely planned, were previously provided for in the briefing and were not carried out in emergency mode when the reactor was shut down. But still, the exact causes of the Chernobyl accident are not known to this day.
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Lack of “safety culture”
After the emergency button was pressed, two explosions occurred, the interval being only a few seconds, and as a result, the reactor was almost immediately destroyed. The State Commission blamed the Chernobyl nuclear power plant personnel entirely for the tragedy; everyone supported this version. However, recent facts have made people doubt this.
The year of the Chernobyl explosion became fatal, but versions are constantly changing, and it is very difficult to come to one thing. It is clear that the human factor played an important role here, but you cannot rely on this alone. Perhaps there was something else here that could not be predicted. And as proof, 20 years later, a new report confirmed that such a categorical opinion turned out to be wrong.
It was confirmed that the actions of the personnel fully complied with the necessary rules, so it was difficult to influence the course of the accident. In addition, nuclear energy experts stated that safety at the nuclear power plant was low, or rather there was no safety culture as such. We can talk a lot about this, but the truth is one: the explosion took place, and its consequences are catastrophic.
Lack of staff awareness
Experts claim that personnel at the Chernobyl nuclear power plant were not aware that there was a danger in the changed working conditions. Before the accident, the ORM was less than the value allowed by the regulations, but the personnel who took over the shift were not aware of the current ORM, and therefore did not know that they were violating the regulations.
Perhaps the most terrible thing is that even after the explosion occurred at the Chernobyl nuclear power plant, the first ones - the firefighters who came to put out the fire - were not aware of the further danger. Few ordinary people could imagine that radiation could be very life-threatening. At that moment, they thought only about destroying the fire, saving what could still be saved. As a result, something terrible happened: out of twenty firefighters, only six survived. This is all very terrible.
Illiterate actions of personnel when working with the reactor
Just 20 years later, KGB officers found themselves at the site of the Chernobyl accident and were able to claim that the clear cause of the explosion was the fourth power unit, some kind of error that was not corrected in time. Perhaps it happened that the block had to be stopped at a certain moment in order for it to come out of the iodine pit, but for some reason this was not done. One of the reasons was that the block began to be raised.
Why were they hiding the causes of the accident?
The causes of the explosion at the Chernobyl nuclear power plant were classified in order to prevent mass panic. After all, the lives and health of many people depended on it. Knowing the true causes of the explosion at the Chernobyl nuclear power plant, people would lose their composure and panic, and this is very undesirable, especially before evacuation.
The year of the Chernobyl explosion seemed like a very ordinary year, but then it became clear that this was not so. However, such a truth could not be hidden for long; the cause of the explosion of the Chernobyl nuclear power plant had to come out sooner or later. The terrible ones appeared within a few days, when people began to die from radiation sickness. Soon, when the radioactive cloud reached Europe, the whole world learned about the great atomic disaster. The cause of the explosion of the Chernobyl nuclear power plant could not be ignored, but at the same time, it is impossible to accurately answer this question even now.
The explosion at the Chernobyl nuclear power plant as a death sentence
On April 27, 1986, after the explosion, more than 100 people were sent to hospital, and already at two o’clock in the afternoon a mass evacuation began, during which more than 45 thousand people were evacuated. People were forced to leave everything they loved, give up their usual way of life and go into the unknown. The Chernobyl accident deprived people of their home, their favorite atmosphere and a sense of personal security. In total, by the end of 1986, about 116 thousand people from 188 settlements were evacuated.
In May 1986, the USSR government decided to mothball the fourth power unit of the Chernobyl nuclear power plant. This was done in order to avoid the release of radionuclides into the environment and prevent further contamination in the station area. Already in November 1986, the so-called “Sarcophagus” was built, that is, an insulating concrete shelter designed to stop the further spread of radiation.
In the first three years after the accident, more than 250 thousand workers visited Chernobyl, sent there in order to minimize the consequences of the disaster. Subsequently, the number of employees increased further. And although the causes of the Chernobyl accident are still unknown, much has been done to minimize the terrible consequences.
If you want to know more, you can enter “Chernobyl NPP causes of the accident” in the search engine. However, do not forget that the Internet is not a very reliable source of information. For example, some sources claim that the death toll from the accident is in the thousands, although this is absolutely not true.
In 1993, the second power unit was installed at the Chernobyl nuclear power plant, and in 1996 the first power unit, and already in 2000 the third was installed, which became the last in this matter.
December 15, 2000 was the last day for Chernobyl, and this marked the end of everything. The great, once powerful nuclear power plant ceased to exist forever.
The Verkhovna Rada of Ukraine came to a decision to completely liquidate the Chernobyl nuclear power plant in 2065. In addition, in the very near future it is planned to build a special storage facility for draining spent nuclear fuel. This project will make the destroyed nuclear power plant safe.
Consequences of a deadly experiment
Quite a lot has already been said about the consequences of the fatal explosion at the Chernobyl nuclear power plant, but the essence remains the same. An Exclusion Zone was formed 30 kilometers around the station. Along with this territory, the explosion at the Chernobyl nuclear power plant especially affected villages and cities within a radius of 100 kilometers. The lands where it was raining at that moment were especially contaminated with radiation. After all, radioactive elements contained in large particles fell along with precipitation. More than five hectares of land were taken out of agricultural use.
It should be noted that the Chernobyl disaster surpasses the notorious Hiroshima and Nagasaki in terms of the power and scale of damage. According to some experts, the explosion at the Chernobyl nuclear power plant provoked the development of diseases in people such as cataracts and thyroid cancer, increased the risk of cardiovascular problems, leukemia and other terrible problems that cannot be avoided even 30 years after the accident.
The explosion of the Chernobyl nuclear power plant turned the idea of human power upside down, since it was then that proof was presented that not everything in this world is subject to man, sometimes what is destined to happen cannot be avoided. But let's take a closer look at what exactly caused the explosion of the Chernobyl nuclear power plant, whether it could have been avoided, and in general, what should be expected in the future. Will we never get rid of the consequences of the terrible event that happened in the eighties of the 20th century?
Echoes of Chernobyl today
The Chernobyl zone, the explosion in the area of which shocked the whole world, became famous throughout the world. Even now, not only Ukrainians are interested in this problem, but also residents of other countries who are interested in ensuring that such a tragedy does not happen again. After all, no matter how sad it is, this tragedy even now poses a danger to every inhabitant on Earth. Moreover, some scientists agree that the biggest problems are just beginning. There is, of course, some truth in this, because the main global catastrophe did not occur on the day of the explosion, but only later, when people began to develop radiation sickness, which is still rampant today.
The event that occurred on April 26, 1986 once again proved that it is stupid to divide people into countries and nationalities, that if some terrible disaster occurs, then everyone around them can suffer, regardless of skin color and material wealth.
The Chernobyl explosion is a clear example of the need to be careful when dealing with nuclear energy, because one slight mistake will lead to a catastrophe on a global scale. Unfortunately, the Chernobyl explosion has already occurred, so we cannot return time and stop this disaster, but at the same time we can protect ourselves and others from the same mistakes in the future.
No one will argue that there is very little positive in the events that occurred on April 26, 1986, however, our task is not only to remember, but also to prevent something like this from happening again. We never know what will happen next, but we must act in such a way as not to harm nature and the environment.
On April 26, 1986, at the Chernobyl nuclear power plant, in the 4th power unit, a huge explosion occurred, as a result of which the nuclear reactor was completely destroyed. This sad event will forever go down in human history as the “accident of the century.”
Explosion at the Chernobyl nuclear power plant. Year 1986, April 26 - a black date in history
The most powerful nuclear power plant in the USSR became a source of release of extremely dangerous pollutants into the environment, due to which 31 people died within the first 3 months, and the number of deaths over the next 15 years exceeded 80. The most severe consequences of radiation sickness were recorded in 134 people due to severe radioactive contamination. The terrible “cocktail” consisted of a large list of elements from the periodic table, such as plutonium, cesium, uranium, iodine, strontium. Deadly substances mixed with radioactive dust covered a huge territory with a mud plume: the European part of the Soviet Union, the eastern part of Europe and Scandinavia. Belarus suffered greatly from the contaminated precipitation. The explosion of the Chernobyl nuclear power plant was compared to the nuclear bombings of Hiroshima and Nagasaki.
How the explosion happened
During the investigation, numerous commissions repeatedly analyzed this event, trying to find out what exactly caused the disaster and how it happened. However, there is no consensus on this matter. A force capable of destroying all life in its path burst out from the 4th power unit. The accident was classified: the Soviet media remained deathly silent for the first days, but the explosion at the Chernobyl nuclear power plant (1986) was recorded abroad as a colossal radiation leak and the alarm was raised. It became impossible to remain silent about the accident. The energy of the peaceful atom was intended to carry civilization forward, towards progress, but changed its trajectory and caused the invisible war between man and radiation.
The explosion at the Chernobyl nuclear power plant, the date of which will be remembered by mankind for centuries, began with a fire in power unit No. 4, the signal about which was received by the control panel at 1.24 am. The fire brigade promptly began extinguishing the fire, successfully extinguishing the fire by 6 a.m., thanks to which the fire could not spread to block No. 3. The level of radiation in the halls of the power unit and near the station was unknown to anyone at that time. What happened in these hours and minutes with the nuclear reactor itself was also unknown.
Reasons and official versions
Analyzing the explosion at the Chernobyl nuclear power plant, the causes of which were inexplicable at first glance, experts put forward many versions. Having summed up the results of the investigation, scientists settled on several options:
1. Disruption and disruption of the operation of circular pumps due to cavitation (formation of a shock wave as a result of a chemical reaction) and, as a consequence, a pipeline breakthrough.
2. Power surge inside the reactor.
3. Low level of security in the enterprise - INSAG version.
4. Emergency acceleration - after pressing the "AZ-5" button.
The latter version, according to many industry experts, is the most plausible. In their opinion, the control and protection rods were brought into active operation precisely by pressing this ill-fated button, which led to the emergency acceleration of the reactor.
This course of events is completely refuted by experts from the Gospromatnadzor commission. Employees put forward their versions of the causes of the tragedy back in 1986, insisting that the positive reactivity was caused by the emergency protection being activated, which is why the explosion of the Chernobyl nuclear power plant occurred.
Certain technical calculations that prove the cause of the explosion due to cavitation on an anti-aircraft missile system refute other versions. According to the chief designer of the Chernobyl Nuclear Power Plant, steam at the entrance to the reactor, as a result of boiling of the coolant in the air defense system, entered the core and distorted the energy-releasing fields. This happened due to the fact that the temperature of the coolant reached the boiling point during the most dangerous period. The emergency acceleration began precisely with active vaporization.
Explosion of the Chernobyl nuclear power plant. Other reasons for the tragedy
In addition, opinions were often voiced about the cause of the explosion as an act of sabotage, which was planned by the United States and carefully hidden by the government of the USSR. This version is supported by photographs of the exploded power unit from an American military satellite, which miraculously found itself in the right place exactly when the explosion occurred at the Chernobyl nuclear power plant. It is very difficult to refute or confirm this theory, and therefore this version remains a guess. It remains only to confirm that indeed in 1986 the explosion of the Chernobyl nuclear power plant resulted in the disabling of secret objects (over-the-horizon radar Duga-1, Chernobyl-2).
The earthquake that occurred at that moment is also cited as the cause of the tragedy. Indeed, shortly before the explosion, seismographs recorded a certain shock in the immediate vicinity of the Chernobyl nuclear power plant. It is the vibration that could provoke the accident that adherents of this version call the reason for the launch of irreversible processes. What seems strange in this situation is the fact that for some reason the neighboring power unit No. 3 was not damaged in any way and did not receive information about the seismic tremors. But no tests were carried out on it...
The most fantastic reason for the explosion has also been put forward - this is possible ball lightning, formed during the bold experiments of scientists. It was she who, if we imagine such a course of events, could well disrupt the operating regime in the reactor zone.
The consequences of the tragedy in numbers
At the time of the explosion, only 1 person died at the station. The very next morning, another employee died from very serious injuries. However, the worst thing began later, when literally within a month another 28 people died. They and 106 other station employees were at work at the time of the disaster and received the maximum dose of radiation.
Fire extinguishing
To extinguish the fire, when a fire was announced in power unit No. 4 of the Chernobyl nuclear power plant, 69 employees included in the fire department, as well as 14 vehicles, were involved. People put out the fire, having no idea about the high level of pollution. The fact is that it was not possible to look at the background radiation meters: one was faulty, the second remained out of reach, under the rubble. That is why no one could even imagine the real consequences of the explosion at that time.
A year of death and sorrow
At approximately 2 a.m., some firefighters began to experience the first symptoms of radiation sickness (vomiting, weakness, and an incomparable “nuclear tan” on their bodies). After first medical aid, the patients were taken to the city of Pripyat. The next day, 28 people were urgently sent to Moscow (6th Radiological Hospital). All the efforts of the doctors were in vain: the fire tamers became so infected that they died within a month. Trees covering an area of almost 10 square meters also died from the huge release of radioactive substances into the atmosphere during the disaster. km. The explosion at the Chernobyl nuclear power plant, the consequences of which were felt not only by the direct participants, but also by residents of three republics of the Soviet Union, forced to take unprecedented safety measures at all similar installations.
Based on the analysis of old and new data, a realistic version of the causes of the Chernobyl accident has been developed. Unlike earlier official versions, the new version provides a natural explanation for the accident process itself and many circumstances preceding the moment of the accident, which have not yet found a natural explanation.
1. Causes of the Chernobyl accident. The final choice between the two versions
1.1. Two points of view
There are many different explanations for the causes of the Chernobyl accident. There are already over 110 of them. And there are only two scientifically reasonable ones. The first of them appeared in August 1986 /1/ Its essence boils down to the fact that on the night of April 26, 1986, the personnel of the 4th unit of the Chernobyl nuclear power plant, in the process of preparing and conducting purely electrical tests, grossly violated the Regulations 6 times, i.e. . rules for safe operation of the reactor. And for the sixth time, so rudely that it couldn’t be ruder - he removed from its core no less than 204 control rods out of 211 standard ones, i.e. more than 96%. While the Regulations required them: “When the operational reactivity margin decreases to 15 rods, the reactor must be immediately shut down” /2, p. 52/. And before that, they deliberately turned off almost all emergency protection. Then, as the Regulations required of them: “11.1.8. In all cases, it is prohibited to interfere with the operation of protections, automation and interlocks, except in cases of their malfunction...” /2, p. 81/. As a result of these actions, the reactor fell into an uncontrollable state, and at some point an uncontrollable chain reaction began in it, which ended in a thermal explosion of the reactor. In /1/ they also noted “carelessness in the management of the reactor installation”, insufficient understanding by “staff of the peculiarities of technological processes in a nuclear reactor” and loss of “sense of danger” by the staff.
In addition, some design features of the RBMK reactor were indicated, which “helped” the personnel to bring a major accident to the dimensions of a catastrophe. In particular, “The developers of the reactor facility did not provide for the creation of protective safety systems capable of preventing an accident in the event of a set of deliberate shutdowns of technical protective equipment and violations of operating regulations, since they considered such a combination of events impossible.” And one cannot but agree with the developers, because deliberately “disabling” and “violating” means digging one’s own grave. Who will do this? And in conclusion, it is concluded that “the root cause of the accident was an extremely unlikely combination of violations of the order and operating regime committed by the personnel of the power unit” /1/.
In 1991, the second state commission, formed by Gosatomnadzor and consisting mainly of operators, gave a different explanation of the causes of the Chernobyl accident /3/. Its essence boiled down to the fact that the reactor of the 4th block had some “design flaws” that “helped” the duty shift to bring the reactor to an explosion. The main ones are usually the positive steam reactivity coefficient and the presence of long (up to 1 m) graphite water displacers at the ends of the control rods. The latter absorb neutrons worse than water, so their simultaneous introduction into the core after pressing the AZ-5 button, displacing water from the control rod channels, introduced such additional positive reactivity that the remaining 6-8 control rods were no longer able to compensate for it. An uncontrollable chain reaction began in the reactor, which led to a thermal explosion.
In this case, the initial event of the accident is considered to be the pressing of the AZ-5 button, which caused the downward movement of the rods. The displacement of water from the lower sections of the control rod channels led to an increase in the neutron flux in the lower part of the core. Local thermal loads on fuel assemblies have reached values exceeding the limits of their mechanical strength. The rupture of several zirconium claddings of the fuel assemblies led to a partial separation of the reactor's upper protective plate from the casing. This resulted in a massive rupture of the technological channels and jamming of all the control rods, which by this moment had passed approximately half the way to the lower end switches.
Consequently, the scientists and designers who created and designed such a reactor and graphite displacers are to blame for the accident, and the personnel on duty have nothing to do with it.
In 1996, the third state commission, in which the operators also set the tone, analyzed the accumulated materials and confirmed the conclusions of the second commission.
1.2. Balance of opinions
Years passed. Both sides remained unconvinced. As a result, a strange situation arose when three official state commissions, each composed of authoritative people in their field, studied, in fact, the same emergency materials, but came to diametrically opposite conclusions. It was felt that there was something wrong there, either in the materials themselves, or in the work of the commissions. Moreover, in the materials of the commissions themselves, a number of important points were not proven, but simply declared. This is probably why neither side could indisputably prove that they were right.
The very relationship of blame between the staff and the designers remained unclear, in particular due to the fact that during the tests the staff “recorded only those parameters that were important from the point of view of analyzing the results of the tests” /4/. That's how they explained it later. This was a strange explanation, because even some of the main parameters of the reactor, which are always and continuously measured, were not recorded. For example, reactivity. “Therefore, the process of development of the accident was restored by calculation using a mathematical model of the power unit using not only printouts of the DREG program, but also instrument readings and the results of a personnel survey” /4/.
Such a long existence of contradictions between scientists and operators has raised the question of an objective study of all materials related to the Chernobyl accident accumulated over 16 years. From the very beginning, it seemed that this should be done on the principles adopted by the National Academy of Sciences of Ukraine - any statement must be proven, and any action must be naturally explained.
Upon careful analysis of the materials of the above commissions, it becomes obvious that their preparation was clearly influenced by the narrow departmental biases of the heads of these commissions, which, in general, is natural. Therefore, the author is convinced that in Ukraine only the National Academy of Sciences of Ukraine, which did not invent, design, build or operate the RBMK reactor, is truly capable of objectively and officially understanding the true causes of the Chernobyl accident. And therefore, neither in relation to the reactor of the 4th unit, nor in relation to its personnel, it simply does not and cannot have any narrow departmental biases. And her narrow departmental interest and direct official duty is the search for objective truth, regardless of whether individual officials from the Ukrainian nuclear energy like it or don’t like it.
The most important results of this analysis are outlined below.
1.3. About pressing the AZ-5 button or doubts develop into suspicions
It was noticed that when you quickly get acquainted with the voluminous materials of the Government Commission to Investigate the Causes of the Chernobyl Accident (hereinafter referred to as the Commission), you get the feeling that it was able to build a rather coherent and interconnected picture of the accident. But when you start reading them slowly and very carefully, in some places you get the feeling of some kind of understatement. As if the Commission underinvestigated something or left something unsaid. This especially applies to the episode of pressing the AZ-5 button.
“At 1 hour 22 minutes 30 seconds, the operator saw on the program printout that the operational reactivity margin was a value requiring immediate shutdown of the reactor. However, this did not stop the personnel, and the tests began.
At 1 hour 23 minutes 04 seconds. the SVR (stop and control valves - auto) TG (turbogenerator - auto) No. 8 were closed.....The existing emergency protection for closing the ISV... was blocked in order to be able to repeat the test if the first attempt was unsuccessful ....
After some time, a slow increase in power began.
At 1 hour 23 minutes 40 seconds, the unit shift supervisor gave the command to press the AZ-5 emergency protection button, upon a signal from which all emergency protection control rods were inserted into the core. The rods went down, but after a few seconds there were blows...."/4/.
The AZ-5 button is an emergency shutdown button for the reactor. It is pressed in the most extreme case, when some emergency process begins to develop in the reactor, which cannot be stopped by other means. But from the quote it is clearly clear that there was no special reason to press the AZ-5 button, since not a single emergency process was noted.
The tests themselves were supposed to last 4 hours. As can be seen from the text, the staff intended to repeat their tests. And this would have taken another 4 hours. That is, the staff was going to conduct tests for 4 or 8 hours. But suddenly, already at the 36th second of the test, his plans changed, and he began to urgently shut down the reactor. Let us remember that 70 seconds ago, taking desperate risks, he did not do this, contrary to the requirements of the Regulations. Almost all authors noted this obvious lack of motivation for pressing the AZ-5 button /5,6,9/.
Moreover, “From a joint analysis of DREG printouts and teletypes, in particular, it follows that the emergency protection signal of the 5th category...AZ-5 appeared twice, and the first - at 01:23:39” /7/ . But there is information that the AZ-5 button was pressed three times /8/. The question is, why press it two or three times, if already the first time “the rods went down”? And if everything is going in order, then why are the staff showing such nervousness? And physicists began to suspect that at 01:23:40. or a little earlier, something very dangerous did happen, which the Commission and the “experimenters” themselves kept silent about, and which forced the staff to sharply change their plans to the exact opposite. Even at the cost of disrupting the electrical testing program with all the attendant troubles, administrative and material.
These suspicions intensified when scientists who studied the causes of the accident using primary documents (DREG printouts and oscillograms) discovered a lack of time synchronization in them. Suspicions intensified even more when it was discovered that for study they were given not the original documents, but their copies, “with no time stamps on them” /6/. This strongly resembled an attempt to mislead scientists regarding the true chronology of the emergency process. And scientists were forced to officially note that “the most complete information on the chronology of events is available only... before the start of the tests at 01:23:04 sec on April 26, 1986.” /6/. And then “the factual information has significant gaps... and there are significant contradictions in the chronology of the reconstructed events” /6/. Translated from scientific-diplomatic language, this meant an expression of distrust in the presented copies.
1.3. About the movement of control rods
And most of these contradictions can, perhaps, be found in the information about the movement of control rods into the reactor core after pressing the AZ-5 button. Let us recall that after pressing the AZ-5 button, all control rods had to be immersed in the reactor core. Of these, 203 rods are from the upper ends. Consequently, by the time of the explosion they should have plunged to the same depth, which was what the arrows of the synchronizers on the control room-4 should have reflected. But in reality the picture is completely different. For example, let's cite several works.
“The rods went down...” and nothing more /1/.
"01 h 23 min: strong impacts, control rods stopped before reaching the lower limit switches. The clutch power supply switch was turned off." This is recorded in the SIUR operational log /9/.
"...about 20 rods remained in the upper extreme position, and 14-15 rods sank into the core no more than 1....2 m..." /16/.
"...the displacers of the emergency rods of the safety control rods traveled a distance of 1.2 m and completely displaced the columns of water located under them...." /9/.
The neutron-absorbing rods went down and almost immediately stopped, going deeper into the core by 2-2.5 m instead of the required 7 m /6/.
“The study of the final positions of the control rods using selsyn sensors showed that about half of the rods stopped at a depth of 3.5 to 5.5 m” /12/. The question is, where did the other half stop, because after pressing the AZ-5 button all (!) rods should go down?
The position of the arrows of the rod position indicators that remained after the accident suggests that... some of them reached the lower limit switches (a total of 17 rods, of which 12 were from the upper limit switches)" /7/.
From the above quotes it is clear that different official documents describe the process of moving the rods in different ways. And from the oral stories of the staff it follows that the rods reached about 3.5 m and then stopped. Thus, the main evidence of the movement of the rods into the core is the oral stories of the personnel and the position of the synchronizer switches in the control room-4. No other evidence could be found.
If the position of the arrows had been documented at the time of the accident, then on this basis it would be possible to confidently reconstruct the process of its occurrence. But, as it was found out later, this position was “recorded according to the readings of the selsyns on the day of April 26, 1986” /5/., i.e. 12-15 hours after the accident. And this is very important, because physicists who have worked with selsyns are well aware of their two “insidious” properties. First, if the selsyns-sensors are subjected to uncontrolled mechanical action, then the arrows of the selsyns-receivers can take any position. Secondly, if the power supply is removed from the selsyns, then the arrows of the receiver selsyns can also take any position over time. This is not a mechanical watch that, when broken, records, for example, the moment a plane crashes.
Therefore, determining the depth of insertion of the rods into the core at the time of the accident by the position of the arrows of the receiver synchronizers at Control Room-4 12-15 hours after the accident is a very unreliable method, because at the 4th block both factors influenced the synchronizers. And this is indicated by data from the work /7/, according to which 12 rods, after pressing the AZ-5 button and before the explosion, traveled a path 7 m long from the upper ends to the lower ones. It’s natural to ask how they managed to do this in 9 seconds, if the standard time for such a movement is 18-21 seconds/1/? There are clearly erroneous readings here. And how could 20 rods remain in the uppermost position if, after pressing the AZ-5 button, all (!) control rods are inserted into the reactor core? This is also clearly erroneous.
Thus, the position of the arrows of the selsyn receivers at the main control room-4, recorded after the accident, generally cannot be considered objective scientific evidence of the insertion of control rods into the reactor core after pressing the AZ-5 button. What then remains of the evidence? Only subjective testimony of highly interested persons. Therefore, it would be more correct to leave the question of inserting rods open for now.
1.5. Seismic shock
In 1995, a new hypothesis appeared in the media, according to which. The Chernobyl accident was caused by a narrowly directed earthquake with a magnitude of 3-4, which occurred in the Chernobyl nuclear power plant area 16-22 seconds before the accident, which was confirmed by the corresponding peak on the seismogram /10/. However, nuclear scientists immediately rejected this hypothesis as unscientific. In addition, they knew from seismologists that an earthquake of magnitude 3-4 with an epicenter in the north of the Kyiv region was nonsense.
But in 1997, a serious scientific work /21/ was published, in which, based on the analysis of seismograms obtained at three seismic stations at once, located at a distance of 100-180 km from the Chernobyl nuclear power plant, the most accurate data about this incident were obtained. It followed from them that at 1 hour 23 minutes. 39 sec (±1 sec) local time, a “weak seismic event” occurred 10 km east of the Chernobyl nuclear power plant. The MPVA magnitude of the source, determined from surface waves, was in good agreement at all three stations and amounted to 2.5. The TNT equivalent of its intensity was 10 tons. It turned out to be impossible to estimate the depth of the source from the available data. In addition, due to the low level of amplitudes on the seismogram and the one-sided location of seismic stations relative to the epicenter of this event, the error in determining its geographical coordinates could not be higher than ±10 km. Therefore, this “weak seismic event” could well have occurred at the location of the Chernobyl nuclear power plant /21/.
These results forced scientists to pay more attention to the geotectonic hypothesis, since the seismic stations where they were obtained turned out to be not ordinary, but hypersensitive, because they monitored underground nuclear explosions all over the world. And the fact that the earth shook 10 - 16 seconds before the official moment of the accident became an indisputable argument that could no longer be ignored.
But it immediately seemed strange that these seismograms did not contain peaks from the explosion of the 4th block at its official moment. Objectively, it turned out that seismic vibrations, which no one in the world noticed, were registered by the station instruments. But for some reason the explosion of the 4th block, which shook the earth so much that it was felt by many, the same devices, capable of detecting an explosion of only 100 tons of TNT at a distance of 12,000 km, were not registered. But they should have registered an explosion with an equivalent power of 10 tons of TNT at a distance of 100-180 km. And this also did not fit into logic.
1.6. A new version
All these contradictions and many others, as well as the lack of clarity in the materials on the accident on a number of issues, only strengthened scientists’ suspicions that the operators were hiding something from them. And over time, a seditious thought began to creep into my head, but didn’t the opposite actually happen? First there was a double explosion of the reactor. A light purple flame 500 m high shot up above the block. The entire building of the 4th block shook. Concrete beams began to shake. “A blast wave saturated with steam burst into the control room (control room-4”). The general light went out. Only three lamps, powered by batteries, remained lit. The personnel at Control Room-4 could not help but notice this. And only after that, having recovered from the first shock, he rushed to press his “stop tap” - the AZ-5 button. But it was already too late. The reactor went into oblivion. All this could have taken 10-20-30 seconds after the explosion. Then, it turns out that the emergency process did not begin at 1 hour 23 minutes. 40 seconds from pressing the AZ-5 button, and a little earlier. This means that the uncontrolled chain reaction in the reactor of the 4th block began before the AZ-5 button was pressed.
In this case, the peaks of seismic activity that clearly contradict the logic, recorded by ultra-sensitive seismic stations in the Chernobyl nuclear power plant area at 01:23:39, receive a natural explanation. This was a seismic response to the explosion of the 4th block of the Chernobyl nuclear power plant.
They also get a natural explanation for the emergency repeated pressing of the AZ-5 button and the nervousness of the personnel in conditions when they were going to calmly work with the reactor for at least another 4 hours. And the presence of a peak on the seismogram at 1 hour 23 minutes. 39 seconds and his absence at the official moment of the accident. In addition, such a hypothesis would naturally explain the hitherto unexplained events that happened just before the explosion, such as “vibrations”, “increasing hum”, “water hammer” from the main circulation pump /10/, “bouncing” of two thousand 80-kilogram pigs "assembly 11" in the Central Hall of the reactor and much more /11/.
1.7. Quantitative evidence
The ability of the new version to naturally explain a number of previously unexplained phenomena is, of course, direct arguments in its favor. But these arguments are rather qualitative in nature. And irreconcilable opponents can be convinced only by quantitative arguments. Therefore, we will use the “proof by contradiction” method. Let us assume that the reactor exploded “a few seconds later” after pressing the AZ-5 button and introducing graphite tips into the reactor core. Such a scheme obviously assumes that before these actions the reactor was in a controlled state, i.e. his reactivity was clearly close to 0ß. It is known that introducing all graphite tips at once can introduce additional positive reactivity from 0.2ß to 2ß depending on the state of the reactor /5/. Then, with such a sequence of events, the total reactivity at some point could exceed the value of 1ß, when an uncontrolled chain reaction with prompt neutrons begins in the reactor, i.e. explosive type.
If this is what happened, then designers and scientists should share responsibility for the accident along with the operators. If the reactor exploded before the AZ-5 button was pressed or at the moment it was pressed, when the rods had not yet reached the core, then this means that its reactivity had already exceeded 1ß before these moments. Then, obviously, all the blame for the accident falls only on the personnel, who, simply put, lost control of the chain reaction after 01:22:30, when the Regulations required them to shut down the reactor. Therefore, the question of what value the reactivity was at the moment of the explosion acquired fundamental importance.
The readings of the standard ZRTA-01 reactimeter would definitely help answer this question. But they could not be found in the documents. Therefore, this issue was solved by different authors through mathematical modeling, during which possible values of total reactivity were obtained, ranging from 4ß to 10ß /12/. The balance of total reactivity in these works consisted mainly of the effect of positive reactivity run-down during the movement of all control rods into the reactor core from the upper end switches - up to +2ß, from the steam effect of reactivity - up to +4ß, and from the dehydration effect - up to +4ß. The effects from other processes (cavitation, etc.) were considered second-order effects.
In all these works, the accident development scheme began with the formation of an emergency protection signal of the 5th category (AZ-5). This was followed by the insertion of all control rods into the reactor core, which contributed to reactivity up to +2ß. This led to acceleration of the reactor in the lower part of the core, which led to the rupture of the fuel channels. Then the steam and void effects came into play, which, in turn, could bring the total reactivity to +10ß at the last moment of the reactor’s existence. Our own estimates of the total reactivity at the moment of explosion, carried out using the method of analogies based on American experimental data /13/, gave a close value - 6-7ß.
Now, if we take the most plausible value of reactivity 6ß and subtract from it the maximum possible 2ß introduced by the graphite tips, it turns out that the reactivity before the insertion of the rods was already 4ß. And such reactivity in itself is quite sufficient for almost instantaneous destruction of the reactor. The lifetime of the reactor at such reactivity values is 1-2 hundredths of a second. No personnel, even the most selective, are able to respond so quickly to the threat that has arisen.
Thus, quantitative estimates of reactivity before the accident show that an uncontrolled chain reaction began in the reactor of the 4th unit before pressing the AZ-5 button. Therefore, pressing it could not be the cause of a thermal explosion of the reactor. Moreover, under the circumstances described above, it no longer mattered at all when this button was pressed - a few seconds before the explosion, at the moment of the explosion or after the explosion.
1.8. What do the witnesses say?
During the investigation and trial, the witnesses who were at the control panel at the time of the accident were actually divided into two groups. Those who were legally responsible for the safety of the reactor said that the reactor exploded after pressing the AZ-5 button. Those who were not legally responsible for the safety of the reactor said that the reactor exploded either before or immediately after pressing the AZ-5 button. Naturally, in their memoirs and testimonies, both of them sought to justify themselves in every possible way. Therefore, this kind of material should be treated with some caution, which is what the author does, considering them only as auxiliary materials. Nevertheless, through this verbal stream of justifications, the validity of our conclusions is quite clearly demonstrated. We quote below some of the testimony.
“The chief operating engineer for the second stage of the nuclear power plant who conducted the experiment.....reported to me that, as is usually done, to shut down the reactor in the event of any emergency, he pressed the emergency protection button AZ-5” /14/.
This quote is from the memoirs of B.V. Rogozhkin, who worked as a station shift supervisor on the emergency night, clearly shows that at the 4th block, an “emergency situation” first arose, and only then the staff began to press the AZ-5 button. And an “emergency situation” during a thermal explosion of a reactor arises and passes very quickly - within seconds. If it has already arisen, then the staff simply does not have time to react.
"All events took place within 10-15 seconds. Some kind of vibration appeared. The hum grew rapidly. The power of the reactor first fell, and then began to increase, beyond regulation. Then - several sharp pops and two "water hammers". The second one is more powerful - with sides of the central hall of the reactor. The lights on the control panel went out, the suspended ceiling slabs fell down, and all the equipment turned off" /15/.
This is how he describes the course of the accident itself. Naturally, without reference to the timeline. And here is another description of the accident given by N. Popov.
"... a hum of a completely unfamiliar character, a very low tone, similar to a human groan was heard (eyewitnesses of earthquakes or volcanic eruptions usually spoke about such effects). The floor and walls shook strongly, dust and small crumbs fell from the ceiling, the fluorescent lighting went out, then immediately there was a dull thud, accompanied by thunderous rumbles..." /17/.
“I. Kirshenbaum, S. Gazin, G. Lysyuk, who were present at the control panel, testified that they heard the command to shut down the reactor immediately before or immediately after the explosion” /16/.
“At this time I heard Akimov’s command to turn off the device. Literally immediately there was a strong roar from the direction of the turbine hall” (From the testimony of A. Kuhar) /16/.
From these readings it already follows that the explosion and the pressing of the AZ-5 button practically coincided in time.
This important circumstance is also indicated by objective data. Let us recall that the AZ-5 button was pressed for the first time at 01:23:39, and the second time two seconds later (teletype data). Analysis of seismograms showed that the explosion at the Chernobyl nuclear power plant occurred in the period from 01 hour 23 minutes 38 seconds - 01 hour 23 minutes 40 seconds /21/. If we now take into account that the shift in the time scale of teletypes in relation to the time scale of the all-Union reference time could be ±2 seconds /21/, then we can confidently come to the same conclusion - the explosion of the reactor and the pressing of the AZ-5 button practically coincided in time. And this directly means that the uncontrolled chain reaction in the reactor of the 4th block actually began before the first press of the AZ-5 button.
But what kind of explosion are we talking about in the testimony of witnesses, the first or the second? The answer to this question is contained in both the seismograms and the readings.
If the seismic station recorded only one of two weak explosions, then it is natural to assume that they registered a stronger one. And according to the testimony of all the witnesses, this was precisely the second explosion. Thus, we can confidently accept that it was the second explosion that occurred in the period from 01 hour 23 minutes 38 seconds - 01 hour 23 minutes 40 seconds.
This conclusion is confirmed by witnesses in the following episode:
“Reactor operator L. Toptunov shouted about an emergency increase in the reactor’s power. Akimov shouted loudly: “Shut down the reactor!” and rushed to the reactor control panel. Everyone had already heard this second command to shut down. This was apparently after the first explosion.... " /16/.
It follows that by the time the AZ-5 button was pressed for the second time, the first explosion had already occurred. And this is very important for further analysis. This is where it will be useful to carry out a simple time calculation. It is reliably known that the first press of the AZ-5 button was made at 01 hours 23 minutes 39 seconds, and the second at 01 hours 23 minutes 41 seconds /12/. The time difference between presses was 2 seconds. And in order to see the emergency readings of the device, realize them and shout “about an emergency increase in power”, you need to spend at least 4-5 seconds. It takes at least another 4-5 seconds to listen, then make a decision, give the command “Shut down the reactor!”, rush to the control panel and press the AZ-5 button. So, we already have a reserve of 8-10 seconds before the second press of the AZ-5 button. Let us remember that by this moment the first explosion had already occurred. That is, it took place even earlier and clearly before the first press of the AZ-5 button.
How much earlier? Taking into account the inertia of a person’s reaction to an unexpected danger, usually measured in several or more seconds, let’s add another 8-10 seconds to it. And we get the period of time that passed between the first and second explosions, equal to 16-20 s.
This estimate of 16 - 20 s is confirmed by the testimony of Chernobyl NPP employees O. A. Romantsev and A. M. Rudyk, who were fishing on the shore of the cooling pond on the emergency night. In their testimony they practically repeat each other. Therefore, we will present here the testimony of only one of them - O. A. Romantsev. Perhaps, it was he who described the picture of the explosion in the greatest detail, as it was seen from a great distance. This is precisely their great value.
“I saw very clearly a flame above block No. 4, which in shape was similar to a candle flame or a torch. It was very dark, dark purple, with all the colors of the rainbow. The flame was at the level of the cut of the pipe of block No. 4. It kind of went back and a second bang was heard, similar to the bursting bubble of a geyser. After 15 - 20 seconds, another torch appeared, which was narrower than the first, but 5-6 times higher. The flame also slowly grew and then disappeared, like the first time . The sound was like a shot from a cannon. Booming and sharp. We went" /25/. It is interesting to note that both witnesses did not hear any sound after the first appearance of the flame. This means that the first explosion was very weak. A natural explanation for this will be given below.
True, the testimony of A. M. Rudyk indicates a slightly different time elapsed between the two explosions, namely 30 s. But this dispersion is easy to understand if we consider that both witnesses observed the scene of the explosion without a stopwatch in their hands. Therefore, their personal temporal sensations can be objectively characterized as follows: the time interval between the two explosions was quite noticeable and amounted to a time measured in tens of seconds. By the way, an employee of the IAE named after. I.V. Kurchatova V.P. Vasilevsky, referring to witnesses, also comes to the conclusion that the time elapsed between the two explosions is 20 s /25/. A more accurate estimate of the number of seconds that passed between two explosions was carried out in this work above - 16 -20 s.
Therefore, it is impossible to agree with the estimates of the value of this period of time at 1 - 3 seconds, as is done in /22/. Because these assessments were made based only on the testimony of witnesses who were in various rooms of the Chernobyl nuclear power plant at the time of the accident; they did not see the overall picture of the explosions and were guided in their testimony only by their sound sensations.
It is well known that an uncontrolled chain reaction ends in an explosion. This means that it started another 10-15 seconds earlier. Then it turns out that the moment of its beginning lies in the time interval from 01 hour 23 minutes 10 seconds to 01 hour 23 minutes 05 seconds. Surprisingly, it was precisely this moment in time that the main witness of the accident for some reason considered it necessary to highlight when he discussed the question of the correctness or incorrectness of pressing the AZ-5 button at exactly 01:23:40 (according to DREG): “I didn’t attach any importance then it doesn’t matter - the explosion would have occurred 36 seconds earlier" /16/. Those. at 01:23:04. As already discussed above, VNIIAES scientists pointed to this same point in time back in 1986 as the moment after which the chronology of the accident, reconstructed from the official copies of emergency documents presented to them, raised doubts in them. Are there too many coincidences? This doesn't happen just like that. Apparently, the first signs of an accident (“vibrations” and “a hum of a completely unfamiliar nature”) appeared approximately 36 seconds before the first press of the AZ-5 button.
This conclusion is confirmed by the testimony of the head of the pre-accident, evening shift of the 4th block, Yu. Tregub, who stayed for the night shift to help with the electrical experiment:
“The run-down experiment begins.
They disconnect the turbine from the steam and at this time look at how long the run-down will last.
And so the command was given...
We didn’t know how the coasting equipment worked, so in the first seconds I perceived... some kind of bad sound appeared... as if the Volga was starting to slow down at full speed and was skidding. Such a sound: doo-doo-doo... Turning into roar. The building began to vibrate...
The control room was shaking. But not like during an earthquake. If you count to ten seconds, a rumble was heard, the frequency of vibrations dropped. And their power grew. Then a blow sounded...
This blow was not very good. Compared to what happened next. A strong blow though. The control room shook. And when the SIUT shouted, I noticed that the main safety valve alarms were going off. Flashed in my mind: “Eight valves...open state!” I jumped back, and at that time the second blow came. This was a very strong blow. The plaster fell down, the whole building went down... the lights went out, then the emergency power was restored... Everyone was in shock...".
The great value of this testimony is due to the fact that the witness, on the one hand, worked as the head of the evening shift of the 4th block and, therefore, knew well its real condition and the difficulties of working on it, and, on the other hand, he already worked on the night shift simply a voluntary assistant and, therefore, was not legally responsible for anything. Therefore, he was able to remember and recreate the overall picture of the accident in the most detail of all the witnesses.
In these testimonies, the following words attract attention: “in the first seconds... some kind of bad sound appeared.” From this it clearly follows that the emergency situation at the 4th unit, which ended in a thermal explosion of the reactor, arose already “in the first seconds” after the start of electrical tests. And from the chronology of the accident it is known that they began at 01:23:04. If we now add a few “first seconds” to this moment, it turns out that the uncontrolled chain reaction on delayed neutrons in the reactor of the 4th block began at approximately 01:23:8-10 sec, which coincides quite well with our estimates of this moment given higher.
Thus, from a comparison of emergency documents and the witness statements cited above, we can conclude that the first explosion occurred approximately in the period from 01:23:20 to 01:23:30. It was he who caused the first emergency pressing of the AZ-5 button. Let us recall that not a single official commission, not a single author of numerous versions could give a natural explanation for this fact.
But why did the operational personnel of the 4th unit, who were not new to the business and, moreover, working under the guidance of an experienced deputy chief operating engineer, still lose control of the chain reaction? Memories provide an answer to this question.
“We did not intend to violate the ORM and did not violate it. Violation is when the indication is deliberately ignored, and on April 26 no one saw a stock of less than 15 rods......But, apparently, we overlooked...” /16/.
“Why Akimov was delayed with the team to shut down the reactor, now you won’t find out. In the first days after the accident, we still communicated until we were scattered into separate wards...” /16/.
These confessions were written by a direct, one might say, main participant in the emergency events many years after the accident, when he was no longer threatened with any trouble either from law enforcement agencies or from his former superiors, and he could write frankly. From them, it becomes obvious to any unbiased person that only the personnel are to blame for the explosion of the reactor of the 4th unit. Most likely, being carried away by the risky process of maintaining the power of a reactor that had fallen into self-poisoning mode through its own fault, at a level of 200 MW, the operating personnel first “overlooked” the unacceptably dangerous removal of control rods from the reactor core in an amount prohibited by the Regulations, and then “delayed” by pressing the AZ-5 button. This is the direct technical cause of the Chernobyl accident. And everything else is misinformation from the evil one.
And here it’s time to end all these far-fetched disputes about who is to blame for the Chernobyl accident, and blame everything on science, as exploiters love to do. Scientists were right back in 1986.
1.9. On the adequacy of DREG printouts
It can be argued that the author’s version of the causes of the Chernobyl accident contradicts its official chronology, based on DREG printouts and given, for example, in /12/. And the author agrees with this - indeed he contradicts it. But if you carefully analyze these printouts, it is easy to notice that this chronology itself after 01 hours 23 minutes 41 seconds is not confirmed by other emergency documents, contradicts the testimony of eyewitnesses and, most importantly, contradicts the physics of reactors. And VNIIAES specialists were the first to draw attention to these contradictions back in 1986, as already mentioned above /5, 6/.
For example, the official chronology, based on DREG printouts, describes the accident process in the following sequence /12/:
01 hour 23 minutes 39 seconds (via teletype) - AZ-5 signal registered. The AZ and RR rods began to move into the core.
01 hour 23 minutes 40 seconds (according to DREG) - the same.
01 hour 23 minutes 41 seconds (via teletype) - Emergency protection signal registered.
01 hour 23 minutes 43 seconds (according to DREG) - Signals for the acceleration period (AZS) and for excess power (AZM) appeared in all side ionization chambers (NIC).
01 hour 23 min 45 sec (according to DREG) - Reduction from 28,000 m3/h to 18,000 m3/h of the flow rates of the main circulation pumps not involved in the rundown, and unreliable readings of the flow rates of the main circulation pumps involved in the rundown...
01 hour 23 minutes 48 seconds (according to DREG) - Restoration of the flow rates of the main circulation pumps not involved in the rundown to 29000 m3/h. Further increase in pressure in the BS (left half - 75.2 kg/cm2, right - 88.2 kg/cm2) and BS level. Triggering of high-speed reducing devices for releasing steam into the turbine condenser.
01 hour 23 minutes 49 seconds - Emergency protection signal "increase in pressure in the reactor space."
While the testimony of, for example, Lysyuk G.V. talk about a different sequence of emergency events:
“...something distracted me. It was probably Toptunov’s cry: “The reactor’s power is growing at an emergency speed!” I’m not sure of the accuracy of this phrase, but that’s the meaning I remember. Akimov with a quick sharp movement jumped to the control panel and tore off the lid and pressed the "AZ-5" button..." /22/.
A similar sequence of emergency events, already cited above, is described by the main witness of the accident /16/.
When comparing these documents, the following contradiction attracts attention. From the official chronology it follows that the emergency increase in power began 3 seconds after the first press of the AZ-5 button. But witness testimony gives the opposite picture: first, an emergency increase in the power of the reactor began, and only then, after a few seconds, the AZ-5 button was pressed. The assessment of the number of these seconds, carried out above, showed that the period of time between these events could be from 10 to 20 seconds.
The DREG printouts directly contradict the physics of reactors. It was already mentioned above that the lifetime of a reactor with a reactivity above 4ß is hundredths of a second. And according to the printouts, it turns out that from the moment of the emergency increase in power, a full 6 (!) seconds passed before the technological channels began to burst.
However, the vast majority of authors for some reason completely neglect these circumstances and take the DREG printouts as a document that adequately reflects the accident process. However, as shown above, this is not actually the case. Moreover, this circumstance has long been well known to the Chernobyl NPP personnel, because the DREG program at the 4th unit of the Chernobyl NPP “was: implemented as a background task, interrupted by all other functions” /22/. Consequently, “...the time of an event in DREG is not the true time of its manifestation, but only the time of entering the signal about the event into the buffer (for subsequent recording on magnetic tape)” /22/. In other words, these events could have occurred, but at a different, earlier time.
This most important circumstance was hidden from scientists for 15 years. As a result, dozens of specialists wasted a lot of time and money on clarifying the physical processes that could lead to such a large-scale accident, relying on contradictory, inadequate DREG printouts and the testimony of witnesses who were legally responsible for the safety of the reactor and therefore had a strong personal interest in disseminating the version - " the reactor exploded after pressing the AZ-5 button." At the same time, for some reason, no attention was systematically paid to the testimony of another group of witnesses who were not legally responsible for the safety of the reactor and, therefore, more inclined to objectivity. And this most important, recently discovered circumstance further confirms the conclusions made in this work.
1.10. Conclusions of the “competent authorities”
Immediately after the Chernobyl accident, five commissions and groups were organized to investigate its circumstances and causes. The first group of specialists was part of the Government Commission, headed by B. Shcherbina. The second is a commission of scientists and specialists under the Government Commission, headed by A. Meshkov and G. Shasharin. The third is the investigative group of the prosecutor's office. The fourth is a group of specialists from the Ministry of Energy, headed by G. Shasharin. The fifth is the Chernobyl Nuclear Power Plant Operators Commission, which was soon liquidated by order of the Chairman of the Government Commission.
Each of them collected information independently of the other. Therefore, in their archives there was a certain fragmentation and incompleteness in emergency documents. Apparently, this determined the somewhat declarative nature of a number of important points in the description of the accident process in the documents they prepared. This is clearly visible from a careful reading, for example, of the official report of the Soviet government to the IAEA in August 1986. Later in 1991, 1995 and 2000. Various authorities established additional commissions to investigate the causes of the Chernobyl accident (see above). However, this shortcoming remained unchanged in the materials they prepared.
It is little known that immediately after the Chernobyl accident, a sixth investigative group formed by “competent authorities” worked to determine its causes. Without attracting much public attention to her work, she conducted her own independent investigation into the circumstances and causes of the Chernobyl accident, relying on her unique information capabilities. Following fresh leads, during the first five days, 48 people were interviewed and interrogated, and photocopies of many emergency documents were made. In those days, as is known, even bandits respected the “competent authorities”, and normal employees of the Chernobyl Nuclear Power Plant would not have lied to them. Therefore, the findings of the “organs” were of extreme interest to scientists.
However, these conclusions, classified as “top secret”, were made known to a very narrow circle of people. Only recently the SBU decided to declassify some of its Chernobyl materials stored in the archives. And although these materials are no longer officially classified, they still remain practically inaccessible to a wide range of researchers. Nevertheless, thanks to his persistence, the author managed to get to know them in detail.
It turned out that preliminary conclusions were made by May 4, 1986, and final ones by May 11 of the same year. For brevity, we present only two quotes from these unique documents that are directly related to the topic of this article.
“...the common cause of the accident was the low culture of nuclear power plant workers. We are not talking about qualifications, but about work culture, internal discipline and a sense of responsibility” (document No. 29 dated May 7, 1986) /24/.
“The explosion occurred as a result of a number of gross violations of operating rules, technology and non-compliance with the safety regime during the operation of the reactor of the 4th block of the nuclear power plant” (document No. 31 dated May 11, 1986) /24/.
This was the final conclusion of the “competent authorities”. They did not return to this issue again.
As you can see, their conclusion almost completely coincides with the conclusions of this article. But there is a "small" difference. The National Academy of Sciences of Ukraine came to them only 15 years after the accident, figuratively speaking, through a thick fog of misinformation from interested parties. And the “competent authorities” finally established the true causes of the Chernobyl accident in just two weeks.
2. Accident scenario
2.1. Origin Event
The new version made it possible to substantiate the most natural scenario of the accident. At the moment it seems like this. At 00 hours 28 minutes on April 26, 1986, switching to electrical testing mode, the personnel at Control Room-4 made a mistake when switching control from the local automatic control system (LAR) to the main range automatic power control system (AP). Because of this, the thermal power of the reactor dropped below 30 MW, and the neutron power dropped to zero and remained so for 5 minutes, judging by the readings of the neutron power recorder /5/. The process of self-poisoning with short-lived fission products automatically began in the reactor. This process itself did not pose any nuclear threat. On the contrary, as it develops, the ability of the reactor to maintain a chain reaction decreases until it stops completely, regardless of the will of the operators. All over the world, in such cases, the reactor is simply shut down, then they wait a day or two until the reactor restores its functionality. And then they launch it again. This procedure is considered ordinary, and did not present any difficulties for the experienced personnel of the 4th block.
But at nuclear power plant reactors this procedure is very troublesome and takes a lot of time. And in our case, it also disrupted the implementation of the electrical testing program with all the ensuing troubles. And then, trying to “finish the tests quickly,” as the staff later explained, they began to gradually remove the control rods from the reactor core. Such a conclusion was supposed to compensate for the decrease in reactor power due to self-poisoning processes. This procedure at nuclear power plant reactors is also common and poses a nuclear threat only if too many of them are removed for the given state of the reactor. When the number of remaining rods reached 15, the operating personnel had to shut down the reactor. This was his direct official responsibility. But he didn't.
By the way, the first time such a violation occurred was at 7:10 a.m. on April 25, 1986, i.e. almost a day before the accident, and lasted until about 14 hours (see Fig. 1). It is interesting to note that during this time the shifts of the operating personnel changed, the shift supervisors of the 4th block changed, the station shift supervisors and other station management changed and, strange as it may seem, none of them raised the alarm, as if everything was in order, although the reactor was already on the verge of explosion.. The conclusion involuntarily suggests itself that violations of this type, apparently, were a common occurrence not only in the 5th shift of the 4th block.
This conclusion is confirmed by the testimony of I.I. Kazachkov, who worked on April 25, 1986 as the head of the day shift of the 4th block: “I’ll say this: we repeatedly had less than the permissible number of rods - and nothing ...”, “... none of us imagined that this was fraught nuclear accident. We knew that this could not be done, but we didn’t think..." /18/. Figuratively speaking, the reactor “resisted” such free treatment for a long time, but the staff still managed to “rape” it and cause it to explode.
The second time this happened was on April 26, 1986, shortly after midnight. But for some reason, the staff did not shut down the reactor, but continued to remove the rods. As a result, at 01:22:30. 6-8 control rods remained in the core. But this did not stop the staff, and they began electrical tests. At the same time, we can confidently assume that the personnel continued removing the rods until the very moment of the explosion. This is indicated by the phrase “a slow increase in power has begun” /1/ and the experimental curve of changes in reactor power as a function of time /12/ (see Fig. 2).
Nobody in the whole world works like this, because there are no technical means of safely controlling a reactor that is in the process of self-poisoning. The staff of the 4th block did not have them either. Of course, none of them wanted to blow up the reactor. Therefore, the withdrawal of rods beyond the permitted 15 could be carried out only on the basis of intuition. From a professional point of view, this was already an adventure in its purest form. Why did they go for it? This is a separate question.
At some point between 01:22:30 and 01:23:40, the personnel's intuition apparently changed, and an excessive number of rods were removed from the reactor core. The reactor switched to the mode of maintaining a chain reaction using prompt neutrons. Technical means for controlling reactors in this mode have not yet been created and it is unlikely that they will ever be created. Therefore, within hundredths of a second, the heat release in the reactor increased 1500-2000 times /5.6/, the nuclear fuel heated up to a temperature of 2500-3000 degrees /23/, and then a process began that is called a thermal explosion of the reactor. Its consequences made the Chernobyl Nuclear Power Plant “famous” throughout the world.
Therefore, it would be more correct to consider the excess withdrawal of rods from the reactor core as the event that initiated the uncontrolled chain reaction. As happened in other nuclear accidents that ended in a thermal explosion of the reactor, in 1961 and in 1985. And after the rupture of the channels, the total reactivity could increase due to steam and void effects. To assess the individual contribution of each of these processes, detailed modeling of the most complex and least developed, second phase of the accident is necessary.
The author's proposed scheme for the development of the Chernobyl accident seems more convincing and more natural than the insertion of all the rods into the reactor core after a belated pressing of the AZ-5 button. Because the quantitative effect of the latter among different authors has a rather large scatter from quite large 2ß to negligibly small 0.2ß. It is unknown which of them was realized during the accident and whether it was realized at all. In addition, “as a result of research by various teams of specialists... it became clear that the mere introduction of positive reactivity only by the control rods, taking into account all the feedback affecting the steam content, is not enough to reproduce such a power surge, the beginning of which was recorded by the centralized control system SCK SKALA IV Chernobyl nuclear power unit" /7/ (see Fig. 1).
At the same time, it has long been known that the removal of control rods from the reactor core itself can give a much larger reactivity run-out - more than 4ß /13/. This is, firstly. And, secondly, it has not yet been scientifically proven that the rods even entered the active zone. From the new version it follows that they could not enter there, because at the moment the AZ-5 button was pressed, neither the rods nor the active zone any longer existed.
Thus, the version of the exploiters, having withstood the test of qualitative arguments, did not stand up to the quantitative test and can be archived. And the scientists’ version, after a small amendment, received additional quantitative confirmation.
Rice. 1. Power (Np) and operational reactivity margin (Rop) of the reactor of the 4th block in the period of time from 04/25/1986 to the official moment of the accident on 04/26/1986 /12/. The oval marks the pre-emergency and emergency periods of time.
2.2. "First Explosion"
An uncontrolled chain reaction in the reactor of the 4th block began in some, not very large part of the core and caused local overheating of the cooling water. Most likely, it began in the southeastern quadrant of the core at a height of 1.5 to 2.5 m from the base of the reactor /23/. When the pressure of the steam-water mixture exceeded the strength limits of the zirconium pipes of the technological channels, they ruptured. The fairly overheated water almost instantly turned into fairly high-pressure steam. This steam, expanding, pushed the massive 2,500-ton reactor lid upward. For this, as it turned out, breaking just a few technological channels is quite enough. This ended the initial stage of the destruction of the reactor and the main one began.
Moving upward, the lid sequentially, like a domino, tore apart the rest of the technological channels. Many tons of superheated water almost instantly turned into steam, and the force of its pressure quite easily threw the “lid” to a height of 10-14 meters. A mixture of steam, fragments of graphite masonry, nuclear fuel, technological channels and other structural elements of the reactor core rushed into the resulting vent. The reactor cover spun in the air and fell back on its edge, crushing the upper part of the core and causing an additional release of radioactive substances into the atmosphere. The impact of this fall can explain the double nature of the “first explosion”.
Thus, from the point of view of physics, the “first explosion” was not actually an explosion as a physical phenomenon, but was a process of destruction of the reactor core by superheated steam. Therefore, Chernobyl NPP employees who were fishing on the shore of the cooling pond during the emergency night did not hear any sound after it. That is why seismic instruments at three ultra-sensitive seismic stations from a distance of 100 - 180 km were able to register only the second explosion.
Rice. 2. Change in power (Np) of the reactor of the 4th block in the period of time from 23:00 on April 25, 1986 to the official moment of the accident on April 26, 1986 (enlarged section of the graph circled in an oval in Fig. 1). Notice the constant increase in reactor power right up to the explosion
2.3. "Second Explosion"
In parallel with these mechanical processes, various chemical reactions began in the reactor core. Of these, the exothermic zirconium-steam reaction is of particular interest. It begins at 900 °C and proceeds violently already at 1100 °C. Its possible role was studied in more detail in work /19/, in which it was shown that in the conditions of an accident in the core of the reactor of the 4th block, only due to this reaction, up to 5,000 cubic meters could be formed within 3 seconds. meters of hydrogen.
When the top “lid” flew into the air, this mass of hydrogen escaped into the central hall from the reactor shaft. Mixed with the air in the central hall, hydrogen formed a detonation air-hydrogen mixture, which then exploded, most likely from an accidental spark or hot graphite. The explosion itself, judging by the nature of the destruction of the central hall, was of a blasting and volumetric nature, similar to the explosion of the famous “vacuum bomb” /19/. It was he who smashed the roof, central hall and other rooms of the 4th block to smithereens.
After these explosions, the process of formation of lava-like fuel-containing materials began in the sub-reactor rooms. But this unique phenomenon is already a consequence of the accident and is not considered here.
3. Main conclusions
1. The root cause of the Chernobyl accident was the unprofessional actions of the personnel of the 5th shift of the 4th unit of the Chernobyl nuclear power plant, who, most likely, being carried away by the risky process of maintaining the power of the reactor, which had fallen into self-poisoning mode due to the fault of the personnel, at the level of 200 MW, at first “overlooked” it unacceptable dangerous and prohibited by regulations removal of control rods from the reactor core, and then “delayed” pressing the emergency shutdown button of the AZ-5 reactor. As a result, an uncontrolled chain reaction began in the reactor, which ended in a thermal explosion.
2. The insertion of graphite displacers of control rods into the reactor core could not have been the cause of the Chernobyl accident, since at the moment the AZ-5 button was first pressed at 01:23 am. 39 sec. There were no longer any control rods or core.
3. The reason for the first press of the AZ-5 button was the “first explosion” of the reactor of the 4th block, which occurred approximately from 01 hours 23 minutes. 20 sec. until 01:23 min. 30 sec. and destroyed the reactor core.
4. The second press of the AZ-5 button occurred at 01:23 am. 41 sec. and practically coincided in time with the second, now real, explosion of the air-hydrogen mixture, which completely destroyed the building of the reactor compartment of the 4th block.
5. The official chronology of the Chernobyl accident, based on DREG printouts, does not adequately describe the accident process after 01:23. 41 sec. VNIIAES specialists were the first to draw attention to these contradictions. There is a need for its official revision, taking into account recently discovered new circumstances.
In conclusion, the author considers it his pleasant duty to express deep gratitude to Corresponding Member of NASU A. A. Klyuchnikov, Doctor of Physical and Mathematical Sciences A. A. Borovoy, Doctor of Physical and Mathematical Sciences E. V. Burlakov, Doctor of Technical Sciences E. M. Pazukhin and Candidate of Technical Sciences V.N. Shcherbin for a critical but friendly discussion of the results obtained and moral support.
The author also considers it his particularly pleasant duty to express deep gratitude to SBU General Yu. V. Petrov for the opportunity to familiarize himself in detail with part of the SBU archival materials related to the Chernobyl accident, and for oral comments on them. They finally convinced the author that the “competent authorities” are truly competent authorities.
Literature
The accident at the Chernobyl nuclear power plant and its consequences: Information from the State Committee of the USSR AE, prepared for a meeting at the IAEA (Vienna, August 25-29, 1986).
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6. IREP report. Arch. No. 1235 dated 02.27.97.
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11. Chronology of the development of the consequences of the accident at the 4th unit of the Chernobyl nuclear power plant and the actions of personnel to eliminate them. Report of the Institute of Nuclear Research of the Academy of Sciences of the Ukrainian SSR, 1990 and Eyewitness Testimonies. Appendix to the report.
12. See, for example, A. A. Abagyan, E.O. Adamov, E.V.Burlakov et. al. "Chernobyl accident causes: overview of studies over the decade", IAEA International conference "One decade after Chernobyl: nuclear safety aspects", Vienna, April 1-3, 1996, IAEA-J4-TC972, p.46-65.
13. McCullech, Millet, Teller. Safety of nuclear reactors//Materials of the International. conf. on the peaceful use of atomic energy, held on August 8-20, 1955. T.13. M.: Foreign publishing house. lit., 1958
15. O. Gusev. "At the borders of Chornobyl Bliskavits", vol. 4, Kiev, view. "Varta", 1998.
16. A.S. Dyatlov. Chernobyl. How it was. LLC Publishing House "Nauchtekhlitizdat", Moscow. 2000.
17. N. Popov. "Pages of the Chernobyl tragedy." Article in the newspaper "Bulletin of Chernobyl" No. 21 (1173), 05.26.01.
18. Yu. Shcherbak. "Chernobyl", Moscow, 1987.
19. E.M. Pazukhin. “The explosion of a hydrogen-air mixture as a possible cause of the destruction of the central hall of the 4th block of the Chernobyl nuclear power plant during the accident on April 26, 1986,” Radiochemistry, v. 39, no. 4, 1997.
20. "Analysis of the current security of the Shelter object and forecast assessments of the development of the situation." ISTC "Shelter" report, reg. No. 3836 dated December 25, 2001. Under the scientific guidance of Dr. Phys.-Math. Sciences A.A. Borovoy. Chernobyl, 2001.
21. V.N.Strakhov, V.I.Starostenko, O.M.Kharitonov et al. “Seismic phenomena in the area of the Chernobyl nuclear power plant.” Geophysical Journal, vol. 19, no. 3, 1997.
22. Karpan N.V. Chronology of the accident at the 4th block of the Chernobyl nuclear power plant. Analytical report, D. No. 17-2001, Kyiv, 2001.
23. V.A.Kashparov, Yu.A.Ivanov, V.P.Protsak et al. “Estimation of the maximum effective temperature and time of non-isothermal annealing of Chernobyl fuel particles during the accident.” Radiochemistry, v. 39, no. 1, 1997
24. "Z arkh_v_v VUCHK, GPU, NKVD, KGB", Special Issue No. 1, 2001. Vidavnitstvo "Sphere".
25. Analysis of the accident at the fourth block of the Chernobyl Nuclear Power Plant. Zv_t. Frequently 1. Deal with the emergency. Code 20/6n-2000. NVP "ROSA". Kyiv. 2001.
