Chernobyl nuclear power plant during construction
The territory of the Polesie region has been inhabited and developed by people for several millennia. By creating new infrastructure, building cities, drying swamps and irrigating lands, people recorded their history.
Pripyat River near the Chernobyl Nuclear Power Plant
Chernobyl and Pripyat
Compared to the young Pripyat, the city of Chernobyl is already several centuries old. Pripyat's time stopped when she reached her 16th birthday. In turn, Chernobyl is considered one of the oldest settlements in Ukrainian Polesie.
A few centuries ago, this city united not only cultural and historical monuments. At the same time, Chernobyl also united different nationalities. Representatives of different nations lived in commonwealth with each other.
Moreover, the modern exclusion zone was previously a real historical place, because there were Tatar burial mounds and the ruins of old monasteries. Of course, there are also memorial sites here from the Great Patriotic War. However, the Chernobyl tragedy on April 26, 1986 made much of the above disappear, while the once historical lands remained mothballed for many centuries.
Cemetery of radioactive equipment in Chernobyl
In what year did the Chernobyl tragedy occur?
The Chernobyl tragedy occurred in a year when the Soviet energy industry was supposed to enter a new stage of development, because in addition to planned experiments, the Chernobyl nuclear power plant was preparing to launch new power units with the RBMK-1000 reactor. The successful use of nuclear resources has drowned out the most important thing that a specialist should have - responsibility. And this is not only responsibility for the safety of others. This is mindfulness while using the gigantic power of nuclear fuel.
The RBMK-1000 reactor and the nuclear fuel it contained turned out to be invincible opponents for the common man. Alluring with its potential, it succumbed and ended up in the hands of man, but in an unexpected moment, when everyone allowed themselves to relax, it brought great tragedy to Chernobyl and its surroundings.
Consequences of the Chernobyl accident
The Chernobyl tragedy of 1986 is considered the largest in human history. The moment the reactor of the fourth power unit exploded was accompanied by the formation of a column of fire that stretched several kilometers upward. This column contained radioactive particles and penetrated even those layers of the atmosphere that it seemed simply could not reach.
Almost 25 years have passed since the terrible event that shocked the whole world. The echoes of this catastrophe of the century will stir the souls of people for a long time, and its consequences will affect people more than once. The disaster at the Chernobyl nuclear power plant - why did it happen and what are its consequences for us?
Why did the Chernobyl disaster happen?
There is still no clear opinion about what caused the disaster at the Chernobyl nuclear power plant. Some argue that the reason is faulty equipment and gross mistakes during the construction of the nuclear power plant. Others see the cause of the explosion as a malfunction of the circulating water supply system, which provided cooling to the reactor. Still others are convinced that the permissible load experiments carried out at the station that ominous night were to blame, during which a gross violation of operating rules occurred. Still others are confident that if there had been a protective concrete cap over the reactor, the construction of which was neglected, such a spread of radiation that occurred as a result of the explosion would not have occurred.
Most likely, this terrible event occurred due to the combination of the listed factors - after all, each of them took place. Human irresponsibility, acting at random in matters relating to life and death, and the deliberate concealment of information about what happened on the part of the Soviet authorities led to consequences, the results of which will echo for a long time to more than one generation of people around the world.
Chernobyl disaster. Chronicle of events
The explosion at the Chernobyl nuclear power plant occurred in the dead of night on April 26, 1986. A fire brigade was called to the scene. Brave and courageous people, they were shocked by what they saw and, judging by the off-scale radiation meters, they immediately guessed what had happened. However, there was no time to think - and a team of 30 people rushed to fight the disaster. For protective clothing, they wore ordinary helmets and boots - of course, they in no way could protect the firefighters from huge doses of radiation. These people have been dead for a long time; they all died a painful death at different times from the cancer that struck them..
By morning the fire was extinguished. However, pieces of uranium and graphite emitting radiation were scattered throughout the territory of the nuclear power plant. The worst thing is that the Soviet people did not immediately learn about the disaster that occurred at the Chernobyl nuclear power plant. This made it possible to maintain calm and prevent panic - this is exactly what the authorities sought, turning a blind eye to the cost of their ignorance for people. The unaware population spent two whole days after the explosion calmly resting in the territory, which had become deadly dangerous, going out into nature, to the river; on a warm spring day, children spent a long time on the street. And everyone absorbed huge doses of radiation.
And on April 28, complete evacuation was announced. 1,100 buses in a convoy transported the population of Chernobyl, Pripyat and other nearby settlements. People abandoned their homes and everything in them - they were only allowed to take with them identity cards and food for a couple of days.
A zone with a radius of 30 km was recognized as an exclusion zone unsuitable for human life. The water, livestock and vegetation in this area were considered unfit for consumption and hazardous to health.
The temperature in the reactor in the first days reached 5000 degrees - it was impossible to approach it. A radioactive cloud hung over the nuclear power plant and circled the Earth three times. To nail it to the ground, the reactor was bombed from helicopters with sand and watered, but the effect of these actions was negligible. There was 77 kg of radiation in the air - as if a hundred atomic bombs had been dropped on Chernobyl at the same time.
A huge ditch was dug near the Chernobyl nuclear power plant. It was filled with the remains of the reactor, pieces of concrete walls, and the clothes of disaster relief workers. For a month and a half, the reactor was completely sealed with concrete (the so-called sarcophagus) to prevent radiation leakage.
In 2000, the Chernobyl nuclear power plant was closed. Work is still underway on the Shelter project. However, Ukraine, for which Chernobyl became a sad “inheritance” from the USSR, does not have the required money for it.
The tragedy of the century that they wanted to hide
Who knows how long the Soviet government would have hidden the “incident” if not for the weather. Strong winds and rains, which inappropriately passed through Europe, carried radiation throughout the world. Ukraine, Belarus and the southwestern regions of Russia, as well as Finland, Sweden, Germany, and Great Britain suffered the most.
For the first time, unprecedented numbers on radiation level meters were seen by employees of the nuclear power plant in Forsmark (Sweden). Unlike the Soviet government, they rushed to immediately evacuate all the people living in the surrounding area before determining that the problem was not their reactor, but the supposed source of the emanating threat was the USSR.
And exactly two days after Forsmark scientists declared a radioactive alert, US President Ronald Reagan held in his hands photographs of the Chernobyl nuclear power plant disaster site taken by a CIA artificial satellite. What was depicted on them would have horrified even a person with a very stable psyche.
While periodicals around the world trumpeted the dangers arising from the Chernobyl disaster, the Soviet press escaped with a modest statement that there had been an “accident” at the Chernobyl nuclear power plant.
Chernobyl disaster and its consequences
The consequences of the Chernobyl disaster made themselves felt in the very first months after the explosion. People living in the areas adjacent to the site of the tragedy died from hemorrhages and apoplexy.
The liquidators of the consequences of the accident suffered: out of a total number of liquidators of 600,000, about 100,000 people are no longer alive - they died from malignant tumors and destruction of the hematopoietic system. The existence of other liquidators cannot be called cloudless - they suffer from numerous diseases, including cancer, disorders of the nervous and endocrine systems. Many evacuees and affected populations in the surrounding areas have these same health problems.
The consequences of the Chernobyl disaster for children are terrible. Developmental delays, thyroid cancer, mental disorders and a decrease in the body's resistance to all types of diseases - this is what awaited children exposed to radiation.
However, the worst thing is that the consequences of the Chernobyl disaster affected not only people living at that time. Problems with carrying a pregnancy to term, frequent miscarriages, stillborn children, frequent births of children with genetic disorders (Down syndrome, etc.), weakened immunity, an astonishing number of children with leukemia, an increase in the number of cancer patients - all these are echoes of the disaster at the Chernobyl nuclear power plant, the end of which will come yet not soon. If it comes...
Not only people suffered from the Chernobyl disaster - all life on Earth felt the deadly force of radiation. As a result of the Chernobyl disaster, mutants appeared - descendants of humans and animals born with various deformations. A foal with five legs, a calf with two heads, fish and birds of unnaturally huge sizes, giant mushrooms, newborns with deformities of the head and limbs - photos of the consequences of the Chernobyl disaster are terrifying evidence of human negligence.
The lesson taught to humanity by the Chernobyl disaster was not appreciated by people. We still treat our own lives with the same carelessness, we still strive to squeeze the maximum out of the riches given to us by nature, everything we need “here and now.” Who knows, maybe the disaster at the Chernobyl nuclear power plant became the beginning to which humanity is moving slowly but surely...
Film about the Chernobyl disaster
We advise everyone who is interested to watch the full-length documentary film “The Battle of Chernobyl”. This video can be watched right here online and for free. Enjoy watching!
Find another video on youtube.com
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.
The world before Chernobyl
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, 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 caused criticism towards the Soviet authorities. 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.
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.
Chernobyl Nuclear Power Plant
The Chernobyl accident. Chronology of events. April 26, which divides the history of Ukraine into two periods - before and after the crash.
Here is a brief chronology of the most important dates associated with the Vladimir Ilyich Lenin Nuclear Power Plant in Chernobyl.
The Chernobyl accident minute by minute, also includes years of events from 1970 to 2016.
1966
The USSR Council of Ministers issues a resolution on June 29, 1966, which approves the plan for commissioning nuclear power plants throughout the entire USSR.
According to preliminary calculations, the commissioned nuclear power plants were supposed to generate 8,000 MW, which would compensate for the shortage of electricity in the central region of the southern part.
1967
From 1966 to 1967, work was carried out to find suitable territories. The work was carried out by the Kyiv branch of the design institute "Teploelektroproekt". As part of the research, sixteen territories were studied, mainly in the Kyiv, Vinnitsa and Zhytomyr regions.
Research of the territories continued until January 1967. As a result, it was decided to stay on the territory in the Chernobyl region, and on January 18, 1967, the territory was officially approved by the Board of the State Planning Committee of the Ukrainian SSR.
On February 2, 1967, the Board of the State Planning Committee of the Ukrainian SSR approved the project for the construction of the Chernobyl Nuclear Power Plant.
On September 29, 1967, the reactors that were to be installed at the Chernobyl Nuclear Power Plant were approved.
There are three approved in total:
- graphite-water reactor RBMK-1000;
- graphite-gas reactor RK-1000;
- water-cooled water reactor VVER.
- Based on the results of the considered options, it was decided to select the RBMK-1000 graphite-water reactor.
1970
The Chernobyl Nuclear Power Plant Directorate has been formed. Projects and urban planning plans for the city of Pripyat have been approved, and its construction has begun.
May 1970 The first pit for the first power unit of the Chernobyl Nuclear Power Plant was marked.
1972
The formation of a special water tank begins to cool the reactors. The reservoir was formed by changing the river bed and building a dam in this bed, as a result, in addition to the dam, the Pripyat River acquired a wide shipping canal.
1976
October 1976 The procedure for filling the reservoir began.
1977
May 1977 commissioning work began at the first power unit.
1978
1979
Pripyat receives city rights.
The Chernobyl nuclear power plant produced 10 billion kilowatt-hours of electricity.
1981
1982
On September 1, a malfunction of reactor No. 1 was recorded. Minor contamination of some damaged fuel evaporation units.
On September 9, the fuel assembly was destroyed and there was an emergency rupture of process channel No. 62-44.
Due to the rupture, the graphite lining of the core was deformed, and a significant amount of radioactive substances from the destroyed fuel assembly was released into the reactor space.
The reactor was repaired and restarted. Information about the accident was published only in 1985.
1983
Construction of reactor No. 4 has been completed.
1984
On August 21, the Chernobyl nuclear power plant produced 100 billion kilowatt-hours of electricity.
1986
“The probability of core destruction occurs once every 10,000 years. Power plants are safe and reliable. They are protected from destruction by three security systems,” said Vitaly Sklyarov, Minister of Energy and Electrification of Ukraine.
Beginning of preparations for the test of the turbocharger of reactor 4. The power of the reactor was reduced.
The reactor power was reduced to 1600 MW, which is half the nominal value.
Reduction of power intended for the reactor's own needs. Turning off the generator 2.
At this hour, the reactor's power is expected to reach only 30 percent. The power, at the request of the dispatcher of the Kyiv Energy District, was reduced for several hours. 23:00 the reactor was operating at 50 percent. Rated power.
The reactor power was reduced to 1600 MW, at which the experiment was carried out. The operator Kievenergo issued a ban on further reduction of power.
The ban on power reduction has been lifted, and a new stage of power reduction has begun.
26 April
The night shift took over the reactor.
The reactor power was reduced to the planned 700 MW.
The reactor power dropped to 500 MW. Due to the complexity of the steering control, the xenon core was “poisoned”, as a result of which the thermal power of the reactor decreased to 30 MW. To increase the reactor's power, the crew removed the control rods. There was only 18 rem left in the core, but at least 30 rem was needed.
The reactor power increased to 200 MW. To prevent the reactor from automatically shutting down, personnel blocked the safety system.
A sharp decrease in reactor reactivity.
Start of testing the turbogenerator. Turbine valves have been trimmed. The reactor's power began to grow uncontrollably.
Emergency braking of the control rods failed because they jammed the channels (and reached a depth of 2-2.5 m instead of the full thrust of 7 m).
Rapid increase in steam power and reactor power (within a few seconds the power was approximately 100 times higher than the required value).
The fuel overheated, the surrounding zirconium dioxide ruptured, molten fuel leaked, and then the pressure passages ruptured. This began to lead to an exothermic reaction.
Emergency signal issued
The first explosion occurred
A second explosion occurred - water vapor was released first, then hydrogen was released. The reactor and parts of the structure were destroyed.
As a result of the explosion, the 2,000-ton plate was thrown onto the reactor vessel. Waste graphite core and molten fuel are discarded.
It is estimated that about 8 of the 140 tons of fuel leaked from the reactor.
The fire crew accepted the call from the Chernobyl nuclear power plant and moved out to extinguish the fire.
An additional fire brigade left the city of Pripyat.
A fire alarm was announced. Employees attempted to restart the reactor's cooling systems, hoping they had not been damaged in the explosion.
Arriving firefighters of the first crew begin to extinguish the fire on the roof of the turbine hall.
The absence of a measuring device was established; the first device was damaged in the explosion. The second is located in an area cut off by rubble. The second fire crew has arrived, some of the firefighters are engaged in extinguishing the fire, the other part of the crew is clearing the rubble to gain access to the measuring equipment.
Firefighters begin to vomit, and their skin begins to burn under their clothes.
The Department of the Interior manages the crisis personnel meeting.
It was decided to put blocks on the road. Fire and police brigades are called.
The officers are not sufficiently trained - they do not have dosimeters or protective clothing.
Viktor Bryukhanov, director of the plant, arrives at the crisis management center located in a bunker under the administrative building of the gym.
The authorities notified central authorities about what happened in Moscow.
The fire is blocked, the possibility of the fire spreading to other rooms is excluded.
Other firefighters arrived from Polesie and Kyiv.
The fire has been completely extinguished.
188 firefighters were called to the scene of the accident.
The exposed firefighters were evacuated to Radiological Hospital No. 6 in Moscow. Air ambulances were used for evacuation.
The morning shift arrived at the power plant. Construction work began at the construction site of reactors 5 and 6. 286 people worked there.
A decision was made to supply water to the damaged reactor area.
A report on the status of the Chernobyl nuclear power plant was sent
The government commission was headed by Valery Legasov. The specialists who arrived at the scene did not expect to see parts of graphite fuel channels.
Data from measuring instruments was received, the level of pollution was established, and a decision was made to evacuate the population.
Requests have been sent to neighboring areas and the city of Kyiv to allocate transport for the evacuation of the population.
The Kyiv Transport Department gives an order to remove all suburban buses from the routes and direct transport to the city of Chernobyl.
Roadblocks have been set up on roads within a radius of 30 kilometers to prevent the movement of civilians through the infected area.
Reactors 1 and 2 are shut down.
The Pripyat city administration collects all administrative personnel.
Instructions are provided to administrative staff of hospitals, schools, and kindergartens.
The processing of the city begins. Laundry soap and additional water tanks were placed in all toilets in the city. The treatment of the premises had to be repeated every hour.
All schools began to work, all children were measured with a radiation device, and medical personnel issued tablets containing iodine.
Processing of the forest area around the Chernobyl nuclear power plant has begun.
Police officers were briefed. District police officers walked around and counted residential buildings, taking into account the number of people living in them.
The first emissions of sand, boron and lead began over the destroyed reactor No. 4.
Two thousand buses and more than one hundred units of military equipment have been assembled on the border of the city of Chernobyl.
The students were sent home with instructions to remain in their apartments. General training has begun in the city.
Instant drop in radioactivity around the power plant.
Instructions are provided at the city police department. The city is divided into six sectors. Each person was assigned a person in charge, and two police officers were assigned to each entrance of a residential building.
Police officers arrived at their places and began instructing and gathering residents.
An official announcement about the accident and the planned evacuation of the population was broadcast on the radio.
The evacuation of people from Pripyat began. Almost 50 thousand. People left their homes within 3.5 hours. 1,200 buses were used for this purpose.
Police officers examined the city of Pripyat and recorded the absence of civilians.
Radioactivity in the air around the Swedish nuclear power plant in Forsmark has increased.
Moscow television reported an “incident” at the Chernobyl nuclear power plant.
The Danish Institute of Nuclear Physics reported that, most likely, the accident at the Chernobyl nuclear power plant completely melted the reactor.
Soviet media reported the death of two people as a result of the accident, the destruction of the reactor unit and the evacuation of the population.
At that time, American spy satellites took the first photographs of the destroyed reactor.
Analysts were shocked by what they saw - a damaged reactor roof and a glowing mass of molten reactor core.
By this day, more than 1,000 tons of material had been dropped from helicopters into the destroyed reactor block.
The wind changed direction, and the radioactive cloud began to move towards Kyiv. Solemn processes took place on the occasion of the May 1st holiday.
May 2
Employees of the liquidation commission established that the core of the exploded reactor is still melting. At that time, the core contained 185 tons of nuclear fuel, and the nuclear reaction continued at a terrifying rate.
Beneath the 185 tons of molten nuclear material was a reservoir containing five million gallons of water. This water was needed as a coolant, and a thick concrete slab separated the nuclear fuel and the water tank.
For molten nuclear fuel, a thick concrete slab was not a sufficient obstacle; the melting active zone burned through this slab, descending to the water.
If the hot reactor core comes into contact with water, a massive steam explosion contaminated with radiation will occur. The result could be radioactive contamination of most of Europe. Based on the death toll, the first Chernobyl explosion would have looked like a minor incident.
Engineers have developed a plan according to which it is possible to avoid a steam explosion. To do this, you need to drain the water in the tank. To drain the water, it is necessary to open the valves located in the flooded radioactive zone.
Three people volunteered for the task:
- Alexey Ananenko senior engineer
- Valery Baspalov mid-level engineer
- Boris Baranov shift supervisor
They all understood that the dose of radiation they would receive during the dive would be fatal to them.
At issue was opening valves in a water tank that was located under the damaged reactor to prevent another explosion - a mixture of graphite and other materials with a temperature of more than 1,200 degrees Celsius with water.
The scuba divers plunged into a dark reservoir and with difficulty found the necessary valves, manually opened them, and then the water drained. After their return, they were taken to the hospital; by the time they were hospitalized, they were in an acute stage of radiation sickness; they could not be saved.
Work has begun on the construction of a tunnel under reactor No. 4 to install a special cooling system there.
A 30-kilometer zone was created around the reactor, from which 90,000 people were evacuated.
A special embankment was built to protect it from pollution.
Reduction of radioisotope emissions.
Firefighters pump water from the basement under the reactor core.
Lugol's drug was started to be given out against radiation in Chernobyl.
It was decided to begin construction of a sarcophagus over the destroyed reactor unit No. 4.
The Chernobyl Atomic Energy Council was fired, accusing it of "lack of responsibility and due to gaps in oversight of the reactor."
Russia sent the first report after to the International Atomic Energy Agency.
There, it was discovered that an extraordinary sequence of events, negligence, mismanagement and safety lapses led to the disaster.
Reactor No. 1 was turned on again.
Work continued on the construction of reactors 5 and 6.
Reactor No. 2 was turned on. Hans Blixa, director of the International Atomic Energy Agency, visited Chernobyl.
Work on assembling sarcophagi for reactor block 4 has been completed; they are designed for 30 years of radiation protection.
400 thousand tons of concrete and more than 7 thousand tons of metal were used.
1987
Reactor No. 3 began producing electricity again.
Work on the construction of reactors 5 and 6 was stopped.
1989
Closure of reactor No. 2 after a turbine fire. It is important to note that there was no risk of infection.
The final decision was made to stop construction of reactors 5 and 6.
1991
Fire in the turbine hall of reactor No. 2.
Power unit No. 2 was put into operation after a major overhaul. While reaching the set power level, one of the turbine generators of the power unit spontaneously turned on.
The reactor power was 50% of the thermal power - at this time one turbogenerator of the unit was operating (at 425 MW).
The second turbogenerator, which turned on spontaneously, operated in “propulsion” mode for only 30 seconds.
As a result of work in the turbogenerator, large loads arose on the axle, which led to the complete destruction of the turbogenerator shaft bearings.
The destruction of the bearings led to depressurization (depressurization) of the generator, which led to the release of large amounts of oil and hydrogen. As a result, a large fire broke out.
During the subsequent investigation into the causes of the accident, it was found that the inclusion of the turbogenerator was caused by the fact that the turbogenerator was not protected from the mode of connection to the network during the rotor run-down.
Spontaneous switching on occurred as a result of loss of insulation between the cable that controls the switch on and the cable through which the signal about the switched off state is transmitted.
There was a defect in the installation of cables - the signal and control cables were placed in one tray.
This Chernobyl accident did not lead to significant contamination of the exclusion zone. The specific activity of the release is estimated at 3.6*10 -5 Ci.
1992
Ukrainian authorities are announcing a competition for new construction that will cover the hastily built sarcophagus at Reactor Building 4.
There were 394 proposals, but only one was considered worthwhile - the construction of a sliding installation.
Assembly testing of structures in Italy. Delivery of the first components for the construction of the sarcophagus.
The first eastern fragment of the dome was raised (5,300 t, 53 m)
2013
A fragment of the roof above reactor block 4 was destroyed under snow pressure. Fortunately, the construction was not compromised.
Second operation to lift the first eastern fragment (9,100 t, 85.5 m)
Third operation to lift the first eastern fragment (11,516 t, 109 m)
October November
Construction of a new and dismantling of the old chimney for power unit No. 3.
2014
The first part of the structure was completed and moved to the parking lot (12,500 t, 112 m)
The first operation to lift the second western fragment of the sarcophagus (4,579 t, 23 m)
The second operation to lift the second western fragment (8,352 t, 85 m).
Third operation to lift the second western fragment of the dome (12,500 t, 112 m)
2015
The beginning of raising the inclined side walls of the sarcophagus.
Work has begun on the electrical and ventilation systems inside the dome.
Joining two parts of the new sarcophagus.
Introduction of new equipment for the dome.
2016
Beginning of the ladle shift operation over reactor block 4 and the old sarcophagus.
The ceremonial completion of the construction of a new dome over reactor unit 4.
The Chernobyl disaster is gradually being forgotten, although it seemed that the most grandiose man-made disaster in the history of mankind in terms of its scale and consequences - the accident at the Chernobyl nuclear power plant - will forever be etched in human memory and will serve as a menacing warning to people living today and their descendants that the nucleus of an atom must always be dealt with talk to YOU about the frivolous, self-confident attitude towards nuclear energy,
The article examines the technical side of this huge tragedy. I tell specialists in advance that much is given here in an extremely simplified form, in some places even to the detriment of scientific accuracy. This was done so that even a person very far from physics and nuclear energy would understand what happened and why on the night of April 25-26, 1986.
Although this disaster is not directly related to military science and history, it was the “stupid and illiterate, rude and stupid” army that had to use the lives and health of its soldiers and officers to correct the mistakes of the “intelligent geniuses of science, the concentration of all the best that is in our society ".
It was highly educated and technically competent nuclear scientists, all these “Promstroykompleks”, “Atomstroy”, Dontekhenergo”, all the venerable academicians, doctors of sciences who managed to arrange this disaster, but were unable to either organize work to eliminate the consequences or manage all the material resources provided at their disposal.
It turned out that they simply did not know what to do now, they did not know the processes occurring in the reactor. You should have seen their shaking hands, confused faces, and pitiful babble of self-justification in those days.
Orders and decisions were either made or cancelled, but nothing was done. And radioactive dust rained down on the heads of Kiev residents.
And only when the head of the chemical forces of the Ministry of Defense got down to work and troops began to gather at the site of the tragedy; When at least some concrete work began, these “scientists” breathed a sigh of relief. Now you can again intelligently argue about the scientific aspects of the problem, give interviews, criticize the mistakes of the military, and tell tales about your scientific foresight.
Physical processes occurring in a nuclear reactor
A nuclear power plant is not much different from a thermal power plant. The whole difference is that in a thermal power plant, steam for turbines driving electric generators is obtained by heating water from the combustion of coal, fuel oil, gas in the furnaces of steam boilers, and in a nuclear power plant, steam is obtained in a nuclear reactor from the same water.
When the atomic nucleus of heavy elements decays, several neutrons are released from it. The absorption of such a free neutron by another atomic nucleus causes excitation and decay of this nucleus. At the same time, several neutrons are also released from it, which in turn... The so-called nuclear chain reaction begins, accompanied by the release of thermal energy.
Attention! First term! Multiplication factor - K. If at a given stage of the process the number of free neutrons formed is equal to the number of neutrons that caused nuclear fission, then K = 1 and each unit of time the same amount of energy is released, but if the number of free neutrons formed is greater than the number of neutrons that caused nuclear fission , then K>1 and at each subsequent moment of time the energy release will increase. And if the number of free neutrons produced is less than the number of neutrons that caused nuclear fission, then K<1 и в каждый следующий момент времени выделение энергии будет уменьшаться.
The task of the power plant duty shift personnel is precisely to keep K approximately equal to 1. If K<1, то реакция будет затухать, количество вырабатываемого пара уменьшаться, пока реактор не остановится. Если К>1 and it cannot be made equal to 1, then what happened at the Chernbyl nuclear power plant will happen.
It seems easy to come to the conclusion that the nuclear fission reaction will increase all the time, because One free neutron during the splitting of an atomic nucleus releases 2-3 neutrons and the number of free neutrons should increase all the time.
To prevent this from happening, tubes containing a substance that absorbs neutrons well (cadmium or boron) are placed between the tubes containing nuclear fuel. By moving such tubes out of the reactor core, or vice versa, introducing such tubes into the zone, they can be used to capture some of the free neutrons, thus regulating their number in the reactor core and maintaining the K coefficient close to unity.
When uranium nuclei fission, nuclei of lighter elements are formed from their fragments. Among them is tellurium-135, which turns into iodine-135, and iodine in turn quickly turns into xenon-135. This xenon is very active in capturing free neutrons. If the reactor operates in a stable mode, then the xenon-135 atoms burn out quite quickly and do not affect the operation of the reactor. However, if there is a sharp and rapid decrease in reactor power for some reason, xenon does not have time to burn out and begins to accumulate in the reactor, significantly reducing K, i.e. helping to reduce reactor power. The phenomenon of so-called (Attention! Second term!) xenon poisoning of the reactor is growing. At the same time, the iodine-135 accumulated in the reactor begins to turn into xenon even more actively. This phenomenon is called (Attention! Third term!) iodine pit.
Under such conditions, the reactor does not respond well to the extension of control rods (tubes with boron or cadmium), because neutrons are actively absorbed by xenon. However, in the end, with a sufficiently significant extension of the control rods from the core, the power of the reactor begins to increase, heat generation increases, and xenon begins to burn out very quickly. It no longer captures free neutrons and their number is rapidly increasing. The reactor gives a sharp jump in power. The control rods lowered at this moment do not have time to absorb the neutrons quickly enough. The reactor may escape the operator's control.
The instructions require that when there is a certain amount of xenon in the core, do not try to increase the power of the reactor, but by lowering the control rods, finally stop the reactor. But the natural removal of xenon from the reactor core takes up to several days. All this time, no electricity is generated by this energy unit.
There is another term - reactor reactivity, i.e. how the reactor responds to operator actions. This coefficient is determined by the formula p=(K-1)/K. At p>0 the reactor accelerates, at p=0 the reactor operates in a stable mode, at p< 0 идет затухание реактора.
Principles of reactor design
Nuclear fuel is black tablets with a diameter of about 1 cm and a height of about 1.5 cm. They contain 2% uranium dioxide 235, and 98% uranium 238, 236, 239. In all cases, with any amount of nuclear fuel, a nuclear explosion cannot develop , because for an avalanche-like rapid fission reaction characteristic of a nuclear explosion, a concentration of uranium 235 of more than 60% is required.
Two hundred nuclear fuel pellets are loaded into a tube made of zirconium metal. The length of this tube is 3.5m. diameter 1.35 cm. This tube is called (Attention! Fifth term!) Fuel element - fuel element.
36 fuel rods are assembled into a cassette (another name is “assembly”).
The RBMK-1000 brand reactor (high-power channel reactorchernob-5.jpg (7563 bytes) with an electric power of 1000 megawatts) is a cylinder with a diameter of 11.8 m and a height of 7 meters, made of graphite blocks (the size of each block is 25x25x60cm. Through each The block passes through a hole - a channel. There are a total of 1872 such holes - channels in this cylinder. 1661 channels are intended for cartridges with nuclear fuel, and 211 for control rods containing a neutron absorber (cadmium or boron).
This cylinder is surrounded by a 1 meter thick wall made of the same graphite blocks, but without holes. The whole thing is surrounded by a steel tank filled with water. This entire structure lies on a metal plate and is covered on top with another plate (lid). The total weight of the reactor is 1850 tons. The total mass of nuclear fuel in the reactor is 190 tons.
In the figure on the left is an assembly with fuel rods in the reactor channel, on the right is a control rod in the reactor channel.
Each reactor supplies steam to two turbines. Each turbine has an electrical power of 500 megawatts. The thermal power of the reactor is 3200 megawatts.
The operating principle of the reactor is as follows:
Water under pressure of 70 atmospheres by main circulation pumps
The main circulation pump is supplied through pipelines to the lower part of the reactor, from where it is pressed through the channels into the upper part of the reactor, washing the assemblies with fuel rods.
In fuel rods, under the influence of neutrons, a nuclear chain reaction occurs with the release of a large amount of heat. The water heats up to a temperature of 248 degrees and boils. A mixture of 14% steam and 86% water is supplied through pipelines to separator drums, where steam is separated from water. Steam is supplied through a pipeline to the turbine.
From the turbine, through a pipeline, steam, which has already turned into water with a temperature of 165 degrees, returns to the separator drum, where it mixes with hot water coming from the reactor and cools it to 270 degrees. This water is again supplied through the pipeline to the pumps. The cycle is complete. Additional water can be supplied to the separator from outside through the pipeline (6).
There are only eight main circulation pumps. Six of them are in operation, and two are in reserve. There are only four separator drums. The dimensions of each are 2.6 m in diameter, 30 meters long. They work simultaneously.
Prerequisites for disaster
The reactor is not only a source of electricity, but also its consumer. Until nuclear fuel is unloaded from the reactor core, water must be continuously pumped through it so that the fuel rods do not overheat.
Typically, part of the electrical power of turbines is selected for the reactor's own needs. If the reactor is shut down (fuel replacement, preventive maintenance, emergency shutdown), then the reactor is powered from neighboring units or an external power grid.
In case of extreme emergency, power is provided from backup diesel generators. However, in the best case scenario, they will be able to start producing electricity no sooner than in one to three minutes.
The question arises: how to power the pumps until the diesel generators reach operating mode? It was necessary to find out how long from the moment the steam supply to the turbines is turned off, they, rotating by inertia, will generate a current sufficient for emergency power supply to the main reactor systems. The first tests showed that the turbines cannot provide electricity to the main systems in the inertial rotation mode (coasting mode).
Dontekhenergo specialists proposed their own system for controlling the magnetic field of the turbine, which promised to solve the problem of power supply to the reactor in the event of an emergency shutdown of the steam supply to the turbine.
On April 25, it was planned to test this system in operation, because... The 4th power unit was still planned to be shut down for repair work that day.
However, it was necessary, firstly, to use something as a ballast load so that measurements could be taken on a running-out turbine. Secondly, it was known that if the thermal power of the reactor dropped to 700-1000 megawatts, the reactor emergency shutdown system (ERS) would be triggered, the reactor would be shut down and it would be impossible to repeat the experiment several times, because xenon poisoning will occur.
It was decided to block the ECCS system and use backup main circulation pumps as a ballast load.
(main central pump)
These were the FIRST and SECOND tragic mistakes that led to everything else.
Firstly, there was absolutely no need to block the ECCS.
Secondly, anything could be used as a ballast load, but not circulation pumps.
It was they who connected the completely distant electrical processes and processes occurring in the reactor.
Chronicle of the disaster
13.05. The reactor power was reduced from 3200 megawatts to 1600. Turbine No. 7 was stopped. Power supply to the reactor electrical systems was transferred to turbine No. 8.
14.00. The emergency shutdown system of the ECCS reactor is blocked. At this time, the Kievenergo dispatcher ordered to delay the shutdown of the unit (end of the week, afternoon, energy consumption is increasing). The reactor is operating at half power, and the ECCS has not been reconnected. This was a gross mistake by the staff, but it did not affect the development of events.
23.10. The dispatcher lifts the ban. The personnel begins to reduce the power of the reactor.
April 26, 1986 0.28. The reactor power has decreased to a level where the system for controlling the movement of the control rods must be transferred from local to general (in normal mode, groups of rods can be moved independently of each other - this is more convenient, but at low power all rods must be controlled from one place and move simultaneously).
This was not done. This was the THIRD tragic mistake. At the same time, the operator makes a FOURTH tragic mistake. It does not command the car to "hold power". As a result, the reactor power is rapidly reduced to 30 megawatts. Boiling in the channels decreased sharply, and xenon poisoning of the reactor began.
The shift staff makes the FIFTH tragic mistake (I would give a different assessment to the actions of the shift at this moment. This is no longer a mistake, but a crime. All instructions require shutting down the reactor in such a situation). The operator removes all control rods from the core.
1.00. The reactor power was raised to 200 megawatts against the 700-1000 prescribed by the test program. This was the second criminal act of the shift. Due to the growing xenon poisoning of the reactor, the power cannot be raised higher.
1.03. The experiment began. The seventh pump is connected to the six operating main circulation pumps as a ballast load.
1.07. The eighth pump is connected as a ballast load. The system is not designed to operate such a number of pumps. The cavitation failure of the main circulation pump began (they simply do not have enough water). They suck water out of the separator drums and its level in them drops dangerously. The huge flow of fairly cold water through the reactor reduced steam generation to a critical level. The machine completely removed the automatic control rods from the core.
1.19. Due to the dangerously low water level in the separator drums, the operator increases the supply of feed water (condensate) to them. At the same time, the staff makes the SIXTH tragic mistake (I would say the second criminal act). It blocks reactor shutdown systems based on signals of insufficient water level and steam pressure.
1.19.30 The water level in the separator drums began to rise, but due to a decrease in the temperature of the water entering the reactor core and its large quantity, boiling there stopped.
The last automatic control rods left the core. The operator makes his SEVENTH tragic mistake. He completely removes the last manual control rods from the core, thereby depriving himself of the ability to control the processes occurring in the reactor.
The fact is that the height of the reactor is 7 meters and it responds well to the movement of the control rods when they move in the middle part of the core, and as they move away from the center, controllability deteriorates. The speed of movement of the rods is 40cm. per second
1.21.50 The water level in the separator drums has slightly exceeded the norm and the operator turns off some of the pumps.
1.22.10 The water level in the separator drums has stabilized. Much less water now enters the core than before. Boiling begins again in the core.
1.22.30 Due to the inaccuracy of the control systems, which were not designed for such an operating mode, it turned out that the water supply to the reactor was about 2/3 of what was required. At this moment, the station computer issues a printout of the reactor parameters indicating that the reactivity margin is dangerously low. However, the staff simply ignored this data (this was the third criminal act that day). The instructions prescribe in such a situation to immediately shut down the reactor in an emergency manner.
1.22.45 The water level in the separators has stabilized, and the amount of water entering the reactor has been brought back to normal.
The thermal power of the reactor slowly began to increase. The staff assumed that the operation of the reactor had been stabilized and it was decided to continue the experiment.
This was the EIGHTH tragic mistake. After all, practically all the control rods were in the raised position, the reactivity margin was unacceptably small, the ECCS was disabled, and the systems for automatically shutting down the reactor due to abnormal steam pressure and water level were blocked.
1.23.04 Personnel blocks the reactor emergency shutdown system, which is triggered in the event of a loss of steam supply to the second turbine, if the first one has already been turned off. Let me remind you that turbine No. 7 was turned off at 13.05 on 25.04 and now only turbine No. 8 was working.
This was the NINTH tragic mistake. (and the fourth criminal act this day). The instructions prohibit disabling this reactor emergency shutdown system in all cases. At the same time, the personnel shuts off the steam supply to turbine No. 8. This is an experiment to measure the electrical characteristics of the turbine in run-down mode. The turbine begins to lose speed, the voltage in the network decreases and the main circulation pump powered by this turbine begins to reduce speed.
The investigation established that if the emergency shutdown system of the reactor had not been turned off by a signal that the steam supply to the last turbine had been stopped, the disaster would not have occurred. Automation would have shut down the reactor.
But the staff intended to repeat the experiment several times using different parameters for controlling the magnetic field of the generator. Shutting down the reactor excluded this possibility.
1.23.30 The main circulation pumps significantly reduced their speed and the flow of water through the reactor core decreased significantly. Steam formation began to rapidly increase. Three groups of automatic control rods went down, but they could not stop the increase in the thermal power of the reactor, because there weren't enough of them anymore. Because The steam supply to the turbine was turned off, its speed continued to decrease, and the pumps supplied less and less water to the reactor.
1.23.40 The shift supervisor, realizing what is happening, orders to press the AZ-5 button. At this command, the control rods move down at maximum speed. Such a massive introduction of neutron absorbers into the reactor core is intended to completely stop nuclear fission processes in a short time.
This was the last TENTH tragic personnel error and the last direct cause of the disaster. Although it should be said that if this last mistake had not been made, then a catastrophe would still have been inevitable.
And this is what happened - at a distance of 1.5 meters under each rod
the so-called “displacer” is suspended
This is an aluminum cylinder 4.5 m long, filled with graphite. Its task is to ensure that when the control rod is lowered, the increase in neutron absorption does not occur abruptly, but more smoothly. Graphite also absorbs neutrons, but somewhat weaker. than boron or cadmium.
When the control rods are raised to their maximum limit, the lower ends of the displacers are 1.25 m above the lower boundary of the core. In this space there is water that is not yet boiling. When all the rods sharply went down the AZ-5 singal, the rods themselves with boron and cadmium had not yet actually entered the active zone, and the displacer cylinders, acting like pistons, displaced this water from the active zone. The fuel rods were exposed.
There was a sharp jump in vaporization. The steam pressure in the reactor increased sharply and this pressure did not allow the rods to fall down. They hovered after walking only 2 meters. The operator turns off the power to the rod couplings.
Pressing this button turns off the electromagnets that keep the control rods attached to the valve. After such a signal is given, absolutely all the rods (both manual and automatic control) are disconnected from their reinforcement and freely fall down under the influence of their own weight. But they were already hanging, supported by steam, and did not move.
1.23.43 Self-acceleration of the reactor began. Thermal power reached 530 megawatts and continued to grow rapidly. The last two emergency protection systems were activated - by power level and by the rate of power growth. But both of these systems control the issuance of the AZ-5 signal, and it was given manually 3 seconds ago.
1.23.44 In a split second, the thermal power of the reactor increased 100 times and continued to increase. The fuel rods became hot, and the swelling fuel particles tore the shells of the fuel rods. The pressure in the core increased many times over. This pressure, overcoming the pressure of the pumps, forced the water back into the supply pipelines.
Further, the steam pressure destroyed part of the channels and steam pipelines above them.
This was the moment of the first explosion.
The reactor ceased to exist as a controlled system.
After the destruction of the channels and steam lines, the pressure in the reactor began to drop and water again flowed into the reactor core.
Chemical reactions of water with nuclear fuel, heated graphite, and zirconium began. During these reactions, rapid formation of hydrogen and carbon monoxide began. The gas pressure in the reactor rapidly increased. The reactor cover, weighing about 1,000 tons, lifted, breaking all the pipelines.
1.23.46 The gases in the reactor combined with atmospheric oxygen, forming an explosive gas, which instantly exploded due to the high temperature.
This was the second explosion.
The reactor lid flew up, turned 90 degrees and fell back down again. The walls and ceiling of the reactor hall collapsed. A quarter of the graphite located there and fragments of hot fuel rods flew out of the reactor. These debris fell on the roof of the turbine hall and other places, creating about 30 fires.
The fission chain reaction has stopped.
The station staff began leaving their jobs at approximately 1.23.40. But from the moment the AZ-5 signal was issued until the moment of the second explosion, only 6 seconds passed. It is impossible to figure out what is happening during this time, and even more so to have time to do something to save yourself. The employees who survived the explosion left the hall after the explosion.
At 1.30 a.m. the first fire brigade, Lieutenant Pravik, arrived at the scene of the fire.
What happened next, who behaved how and what was done correctly and what was wrong is no longer the topic of this article.
author Yuri Veremeev
Literature
1. Journal "Science and Life" No. 12-1989, No. 11-1980.
2.X. Kuhling. Handbook of Physics. ed. "World". Moscow. 1983
3. O.F.Kabardin. Physics. Reference materials. Education. Moscow. 1991
4.A.G.Alenitsin, E.I.Butikov, A.S.Kondratiev. Brief physical and mathematical reference book. The science. Moscow. 1990
5. Report of the IAEA expert group “On the causes of the accident of the RBMK-1000 nuclear reactor at the Chernobyl power plant on April 26, 1986.” Uralurizdat. Ekaterinburg. 1996
6. Atlas of the USSR. Main Directorate of Geodesy and Cartography under the Council of Ministers of the USSR. Moscow. 1986