Accidents at Nuclear Power Plants: When Nuclear Power Becomes Dangerous. Accidents at nuclear power plants: the likelihood of a global outcome

Although nuclear energy does provide carbon-free energy at reasonable prices, it also has its own dangerous side in the form of radiation and other disasters. The International Atomic Energy Agency evaluates accidents at nuclear facilities on a special 7-point scale. The most serious events are classified as the highest category - the seventh, while the 1st level is regarded as minor. Based on this system for assessing nuclear disasters, we offer a list of the five most dangerous accidents at nuclear facilities in the world.

1 place.

The accident at a nuclear facility in Chernobyl is recognized by all experts as the worst disaster in the history of nuclear energy. This is the only accident at a nuclear facility that has been classified by the International Atomic Energy Agency as the worst ever. The largest man-made disaster broke out on April 26, 1986, at the 4th block of the Chernobyl nuclear power plant, located in the small town of Pripyat. The destruction was explosive, the reactor was completely destroyed, and a large amount of radioactive substances was released into the environment. At the time of the accident, the Chernobyl nuclear power plant was the most powerful in the USSR. 31 people died during the first three months after the accident; the long-term effects of exposure, identified over the next 15 years, caused the death of 60 to 80 people. 134 people suffered from radiation sickness of varying severity, more than 115 thousand people from the 30-kilometer zone were evacuated. More than 600 thousand people took part in the liquidation of the consequences of the accident. The radioactive cloud from the accident passed over the European part of the USSR, Eastern Europe and Scandinavia. The station permanently stopped its work only on December 15, 2000.

2nd place.

"Kyshtym accident" - a very serious man-made radiation accident at the Mayak chemical plant located in the closed city of Chelyabinsk-40 (since the 1990s - Ozyorsk). The accident got its name Kyshtym for the reason that Ozyorsk was classified and was not on the maps until 1990, and Kyshtym is the city closest to it. On September 29, 1957, due to the failure of the cooling system, an explosion occurred in a tank with a volume of 300 cubic meters, which contained about 80 m3 of highly radioactive nuclear waste. The explosion, estimated at tens of tons of TNT, destroyed the container, the concrete floor 1 meter thick and weighing 160 tons was thrown aside, about 20 million curies of radiation were released into the atmosphere. Part of the radioactive substances were raised by the explosion to a height of 1-2 km and formed a cloud consisting of liquid and solid aerosols. Within 10-11 hours, radioactive substances fell out over a distance of 300-350 km in the northeast direction from the explosion site (in the direction of the wind). More than 23,000 square kilometers ended up in a zone contaminated with radionuclides. On this territory there were 217 settlements with more than 280 thousand inhabitants, the closest to the epicenter of the disaster were several factories of the Mayak plant, a military camp and a colony of prisoners. To eliminate the consequences of the accident, hundreds of thousands of servicemen and civilians were involved, who received significant doses of radiation. The territory that was exposed to radioactive contamination as a result of an explosion at a chemical plant was called the “East Ural radioactive trace”. The total length was approximately 300 km, with a width of 5-10 km.

From the memoirs from the oykumena.org website: “Mom began to get sick (there were frequent fainting, anemia) ... I was born in 1959, I had the same health problems ... We left Kyshtym when I was 10 years old. I'm a bit of an unusual person. Strange things happened during my life... I foresaw the catastrophe of the Estonian liner. And she even talked about the collision of planes with a friend of the stewardess ... She died.

3rd place.

Windscale Fire, UK. Rating: 5 (accident with risk to the environment)

On October 10, 1957, the operators of the Windscale station noticed that the temperature of the reactor was steadily rising, when the opposite should be happening. First of all, everyone thought about the malfunction of the reactor equipment, which two workers of the station went to inspect. When they got to the reactor itself, they saw to their horror that it was on fire. At first, the workers did not use water because the station operators expressed concern that the fire was so hot that the water would disintegrate instantly, and the hydrogen in the water was known to cause an explosion. All tried means did not help, and then the station staff opened the hoses. Thank God, the water was able to stop the fire without any explosion. An estimated 200 people have developed cancer in the UK due to Windscale, and half of them have died. The exact number of casualties is unknown as the British authorities tried to cover up this disaster. Prime Minister Harold Macmillan feared that the incident could undermine public support for nuclear projects. The problem of counting the victims of this catastrophe is aggravated by the fact that the radiation from Windscale spread hundreds of kilometers throughout northern Europe.

4th place.

Three Mile Island, USA. Rating: 5 (accident with risk to the environment)

Until the Chernobyl accident seven years later, the accident at the Three Mile Island nuclear power plant was considered the largest nuclear accident in the history of the world and is still considered the worst nuclear accident in the United States. On March 28, 1979, early in the morning, there was a major accident at reactor unit No. 2 with a capacity of 880 MW (electric) at the Three Mile Island nuclear power plant, located twenty kilometers from the city of Harrisburg, Pennsylvania and owned by Metropolitan Edison. Unit 2 at the Tree Mile Island nuclear power plant did not appear to be equipped with an additional safety system, although such systems are available at some units of this nuclear power plant. Despite the fact that the nuclear fuel was partially melted, it did not burn through the reactor vessel and the radioactive substances mostly remained inside.

According to various estimates, the radioactivity of noble gases released into the atmosphere ranged from 2.5 to 13 million curies, but the release of dangerous nuclides such as iodine-131 was insignificant. The territory of the station was also contaminated with radioactive water leaked from the primary circuit. It was decided that there was no need to evacuate the population living near the station, but the authorities advised pregnant women and preschool children to leave the 8-kilometer zone. Officially, work to eliminate the consequences of the accident was completed in December 1993. The decontamination of the territory of the station was carried out, the fuel was unloaded from the reactor. However, some of the radioactive water has soaked into the concrete of the containment and this radioactivity is almost impossible to remove. Operation of the station's other reactor (TMI-1) was resumed in 1985.

5th place.

On September 30, 1999, the worst nuclear tragedy for the Land of the Rising Sun occurred. Japan's worst nuclear accident took place more than a decade ago, though it was outside of Tokyo. A batch of highly enriched uranium was prepared for a nuclear reactor that had not been used for more than three years. Plant operators were not trained in how to handle such highly enriched uranium. Not understanding what they were doing in terms of possible consequences, the "specialists" put much more uranium in the tank than needed. Moreover, the reactor vessel was not designed for this type of uranium. ... But the critical reaction can no longer be stopped, and two of the three operators who worked with uranium then die from radiation. After the disaster, about a hundred workers and those who lived nearby were hospitalized with a diagnosis of "irradiation", 161 people who lived a few hundred meters from the nuclear power plant were subject to evacuation.

It is exactly 60 years since the launch of the world's first nuclear power plant. On June 27, 1954, a nuclear power plant with an AM-1 (Atom peaceful) reactor with a capacity of 5 MW gave industrial current and opened the way to the use of atomic energy for peaceful purposes. The station successfully operated for 48 years, then it was stopped for economic reasons.

The reactor of the first nuclear power plant was permanently shut down on April 29, 2002. Since then, dozens of nuclear power plants have been built, but not all of them had such a peaceful history.

"RR" decided to remember 10 the largest accidents at nuclear power plants.

1.Windscale, UK

The Windscale facility was built to produce plutonium, but when the United States created a tritium atomic bomb, the complex was converted to produce tritium for the needs of Great Britain. To do this, the reactor had to operate at higher temperatures than those for which it was originally designed. As a result, on October 10, 1957, a fire broke out.

At first, the operators were reluctant to extinguish the reactor with water because of the threat of an explosion, but eventually gave up and flooded it. A huge amount of water contaminated with radiation got into the environment. In 2007, studies showed that more than two hundred residents of the surrounding territories fell ill with cancer.

The nuclear power plant at Windscale was shut down and closed.

2. Three Mile Island, USA

Before Chernobyl, the accident at Three Mile Island was considered the largest in the history of nuclear energy. The incident took place on March 28, 1979 in Pennsylvania. The cooling system failed and this caused a partial meltdown of the reactor's nuclear fuel elements. Fortunately, a complete meltdown was avoided, and the disaster did not occur. But, despite the favorable outcome, the consequences of the incident for the American nuclear industry were enormous. The meltdown led to an increase in the radiation background on the territory of the station. There were no casualties among the population, but 140 thousand people were forced to leave their homes. The consequences of the accident were eliminated in 1993, 14 years later.

The accident caused many Americans to reconsider their opinion about the use of atomic energy. As a result, the construction of new nuclear power plants was frozen for 13 years.

3. Chernobyl, Ukraine

On April 26, 1986, the fourth power unit was destroyed Chernobyl nuclear power plant. The reactor was completely destroyed, and a large amount of radioactive substances was released into the environment.

The main damaging factor was radioactive contamination. A cloud formed from the burning reactor, which carried radioactive materials across much of Europe.

During the first three months after the explosion, more than 30 Human. The long-term effects of exposure over the next 15 years caused the death of 60 to 80 people. 134 people suffered radiation sickness. 115 thousand people were evacuated within a radius of 30 kilometers. More than 600 thousand people were involved in the elimination of the consequences of the accident.

The liquidation of the consequences cost the Soviet Union an amount close to 25 billions of dollars. All this left a certain imprint on the course of the investigation of its causes. The approach to interpreting the facts and circumstances of the accident has changed over time, and there is still no complete consensus.

4. Tomsk, Russia

The case turned out to be very hidden in Tomsk. In April 1993, the Soviet Union reported an explosion at a secret nuclear fuel reprocessing facility. There was a leak from the nuclear complex at the facility, followed by an explosion.

It was believed that this object is part of a complex nuclear technological cycle for creating components of nuclear weapons, because the authorities tried their best to prevent information leakage. Information about the victims has not yet been established. The area remains closed today.

5. Monju, Japan

The Monju reactor is notable for producing more plutonium than it consumes. He began work in August 1995. But four months later, more than a ton of liquid leaked from the second container of the cooling system. The fire and the subsequent wave of public protests caused the reactor to shut down for fourteen years old.

As a result of four consecutive releases of radioactive substances, about 278 Human. Emissions in power are equal to two hundred atomic bombs, similar to those that were dropped on Hiroshima at the end of World War II.

An official investigating the situation later committed suicide by throwing himself off the roof of a hotel in Tokyo. He was accused of trying to hide the fact of the accident, fearing the possible consequences.

6. Bohunice, Czech Republic

The nuclear power plant in Bohunice was the very first in Czechoslovakia. The reactor was an experimental design to run on uranium. But there were many accidents at the first complex of its kind. So many that they had to close it more than 30 times.

The worst accident happened on February 22, 1977. One of the workers, during a fuel change, incorrectly pulled out the reactor power control rod. Such a small mistake caused the largest leak. As a result The incident earned Level 4 on the International Nuclear Event Scale from 1 to 7.

The government covered up the incident, so no casualties are known. But in 1979, the government of Czechoslovakia decommissioned the station. It is expected to be dismantled 2033 year.

7. Tokaimura, Japan

Japan after the Chernobyl tragedy generally became one of the epicenters of leaks and explosions. The accident at the uranium processing plant in the Japanese village of Tokaimura occurred on September 30, 1999. There was no explosion, but the result of the nuclear reaction was intense gamma and neutron radiation from the sump, which triggered an alarm.

As a result, he was evacuated 161 man from 39 residential buildings within a radius 350 meters from the enterprise. 11 hours after the start of the accident, at one of the sites outside the plant, the level of gamma radiation in 0,5 millisieverts per hour, which is about 1000 times higher than the natural background.

A person does not stop his rapid development for a second, innovative technical achievements open up new horizons for him. A breakthrough in all industries was the creation of nuclear power plants, which quite naturally created inconveniences with accidents and malfunctions. In this material you will find a list of all the most serious, destructive and large-scale man-made accidents that have most often occurred at nuclear power plants since 1944. Since that moment, there are 16 biggest incidents, which you can read about below.

Top 16 man-made accidents

1. September 1, 1944 due to the explosion of uranium hexafluoride at the Oak Ridge National Laboratory, located in Tennessee, USA, hydrofluoric acid was formed. As a result, five people suffered from acid burns and inhalation of a mixture of acid and radioactive vapors at the facility. Three were seriously injured, and two could not be saved.

2. In the Soviet Union, the first major radiation accident happened four years later, June 19, 1948. It happened at facility "A" (Mayak plant, Chelyabinsk region.) after the nuclear reactor for the production of weapons-grade plutonium reached its declared design capacity, literally the next day. The so-called "goat" was due to the local fusion of several uranium blocks with the graphite surrounding them. This happened due to insufficient cooling of these very blocks. Irradiation was received by all the male personnel of the reactor, and the soldiers of the construction battalions involved in the elimination of the accident. The "goaty" channel was manually cleared for nine days, by reaming.

3. March 3, 1949 About 124,000 people were exposed to radiation, and 41 settlements were affected. The tragedy happened as a result of a mass discharge of highly active liquid radioactive waste into the Techa River by the Mayak plant. The average individual dose of 210 m3v was received by 28,100 people who lived in the coastal settlements of the Techa River. Some of the victims had cases of chronic radiation sickness.

4. Day December 12, 1952 went down in history as the date of the world's first serious accident at a nuclear power plant. The reason for this was a technical error made by the personnel of the Chalk River Nuclear Power Plant in Ontario. Overheating and partial melting of the core occurred. The land near the Ottawa River absorbed about 3,800 cubic meters of radioactively contaminated water. Thousands of curies of fission products got into the environment.

5.November 29, 1955 through the fault of man the accident occurred at the American experimental reactor EBR-1, located in the US, Idaho. Due to the incorrect actions of the operator during the experiment with plutonium, the reactor self-destructed, and 40% of its core burned out.

6. September 29, 1957 there was a "Kashtym" accident. The incident happened in the Chelyabinsk region, where a container containing 20 million curies of radioactivity exploded at the Mayak Production Association. The power of the explosion was equal to the explosion of 70-100 tons of TNT. Then the East Ural radioactive trace was formed, which covered an area of ​​​​more than 20 thousand square meters. km. Residents of the Sverdlovsk, Tyumen and Chelyabinsk regions suffered from the radioactive cloud. More than five thousand people were subjected to single exposure to 100 roentgens in the first hours after the explosion, experts announced. Between 25,000 and 30,000 military personnel took part in the liquidation of the consequences of the catastrophe, classified in Soviet times, from 1957 to 1959.

7. October 10, 1957 there was a big accident in Windscale, UK. Due to an error made during the operation of one of the two reactors for the production of weapons-grade plutonium, the temperature of the fuel in the reactor increased sharply. A fire broke out in the core, which lasted 4 days. As a result of damage to 150 technological channels, radionuclides were released. 11 tons of uranium perished in the fire. The radioactive cloud reached the territory of Germany, Denmark, Belgium and Norway. A large area of ​​Ireland and England was polluted.

8. In the spring of 1967, in April, again reminded of itself software "Mayak". An area of ​​1,800 square kilometers was contaminated with radioactive dust of about 600 Ku of activity. This happened as a result of the fact that Lake Karachay, used by Mayak as a dumping ground for dumping liquid waste, became very shallow. Because of this, 2-3 hectares of the coastal strip were exposed, and the same amount of the lake bottom. About 40 thousand people lived in the affected area.

9.In 1969 a cave was permanently walled up, contaminated with radioactive emissions after the accident of an underground nuclear reactor in Switzerland, in the city of Lucens. In the same year, 1969, there was an accident at the Saint Lawrence nuclear power plant in France. Due to the inattention of the night shift operator, the fuel channel was loaded incorrectly, which led to the explosion of the launched reactor, with a power of 500 MW. As a result, the elements overheated and melted, about 50 kg of liquid fuel leaked out.

10. January 18, 1970 there was a disaster at the Krasnoye Sormovo plant located in Nizhny Novgorod. The incident happened during the construction of the nuclear submarine K 320. As a result of the unauthorized launch of the reactor, which worked at exorbitant power for about 15 seconds, the zone of the workshop where the ship was being built was contaminated. About 1,000 people were in the shop at the time of the accident. Due to the closeness of the workshop, it was possible to avoid radioactive contamination of the area. Many workers were sent home that day without proper medical attention and decontamination treatment. Three of the six delivered to the Moscow hospital died from acute radiation sickness, the rest gave a non-disclosure subscription for 25 years. More than a thousand people took part in the work to eliminate the accident until April 24, 1970. Only 380 of them were still alive by January 2005.

11. The fire at the Browns Ferry reactor in Alabama, USA, cost $10 million. There was this fire that lasted seven hours March 22, 1975. It all happened due to the fact that a worker, with a lit candle in his hands, decided to close up an air leak in a concrete wall. Due to the draft, the fire spread through the cable channel. This incident put the nuclear power plant out of action for a whole year.

12. The accident at the Trimal Island nuclear power plant has become the largest in the United States. It happened March 28, 1979 in the state of Pennsylvania. Due to gross errors of operators and a series of equipment failures, the core of the second power unit of the nuclear power plant was melted by 53%. 200 thousand people were evacuated from the affected area. In addition, inert radioactive gases, iodine and xenon, were released into the atmosphere. 185 cubic meters of weakly radioactive water got into the Sukuahana River.

13. The biggest nuclear accident in history, occurred on the night of 25 to 26 April 1986 . In Ukraine, at the fourth block of the Chernobyl nuclear power plant, the reactor core was partially destroyed, fission fragments went beyond the zone. Experts say that this happened due to an experiment attempt to remove additional energy during the operation of the main reactor. 190 tons of radioactive substances entered the atmosphere. 8 out of 140 tons of radioactive fuel were in the air. As a result of the fire, which lasted almost two weeks, other hazardous substances continued to leave the reactor. The population of Chernobyl experienced 90 times more radiation than the bomb that fell on Hiroshima. Everything within a radius of 30 km was subjected to radioactive contamination. The total area of ​​pollution is 160 thousand square kilometers. Belarus, northern Ukraine and western Russia were affected by the accident. The territory of 60 thousand square kilometers, which included 19 Russian regions with a population of 2.6 million people, was polluted.

14. The biggest nuclear accident in Japanese history happened September 30, 1999 . Due to a mistake by personnel at a plant that specializes in the manufacture of fuel for nuclear power plants in the town of Tokaimura, located in the prefecture of Ibaraki, an uncontrolled chain reaction began, which lasted 17 hours. A dose exceeding the annual allowable level was received by 119 people. A total of 439 workers were irradiated. Of the three people who received a critical dose, two died.

15. August 9, 2004 320 kilometers west of Tokyo, on the island of Honshu, an accident occurred at the Mihama nuclear power plant. A super-powerful release of hot steam (about 200 degrees Celsius) occurred in the turbine of the third reactor. All nearby employees received severe burns. At the time of the accident, about 200 people were in the building where the third reactor is located. 4 people died and 18 others were injured. No leaks of radioactive materials were found. According to the number of victims, this accident was the most serious in Japan.

16. As a result of the most powerful earthquake in the history of Japan March 11, 2011 , A turbine at the Onagawa nuclear power plant was destroyed. The resulting fire was quickly extinguished. The situation at the Fukushima-1 nuclear power plant was much more serious, where, due to the shutdown of the cooling system, nuclear fuel melted in the reactor of block No. 1. In connection with the detected leak outside the block, an evacuation was carried out in a 10-kilometer zone around the nuclear power plant. The next day, the NHK broadcaster showed pictures showing the collapsed wall of the nuclear power plant, where the explosion was reported by the media.

People once believed that nuclear energy would one day solve all of mankind's energy problems. From nuclear power plants to airliners that need to be recharged every 22 years, the great atomic discoveries have gone hand in hand with renewable energy since World War II. Under certain conditions, the energy of the atom can be quite safe and give heat to millions of people a year. But sometimes that warmth can be unbearable.

Throughout human history, many lives have been lost due to the unfortunate events associated with nuclear energy.

Texas incident

On April 16, 1947, the worst harbor explosion in US history occurred. The French cargo ship Grandcamp was carrying a cargo of ammonium nitrate, which is commonly used as a fertilizer and to make explosives in atomic weapons.

A lit cigarette thrown by one of the dockers started a fire at the loading dock. It quickly spread into one of Grandcamp's cargo holds and ignited the ammonium nitrate.

The ship's captain ordered the hatches to be battened down to contain the fire, but the rise in temperature only improved the conditions for the volatile chemical to explode. The High Flyer, a nearby ship carrying sulfur, was also affected and exploded a day later by fires caused by the Grandcamp explosion.

Poisonous gas quickly filled the air above the city. Unfortunately, it just so happened that the workers of the telephone operator were on strike at the same time, so the ambulance workers could not quickly pick up victims of toxins in the air. More than 500 people died as a result of this incident, including 28 firefighters involved in extinguishing a fire in the dock.

As a result of this event, new security measures have been put in place to guarantee the safe transport of ammonium nitrate. The docks have a central response system to quickly respond to emergencies, and shipping companies have been required to use special sealed containers and store chemicals away from other hazardous materials.

Titan II rocket explosion

On September 18, 1980, a rocket exploded near Damascus, Arkansas. It happened because a member of the repair team dropped a 4-kilogram nozzle from the rocket platform and pierced the lower fuel tank of the rocket. David Powell violated an Air Force technical order to use a torque wrench instead of the previously used ratchet when making repairs. As soon as the pilots saw a fuel vapor leak in the bunker, all crew members were evacuated to the surface.

Dave Livingston and Geoffrey Kennedy, two repair experts, were called to the bunker to check on the damage to the rocket. They went inside and found that the oxidizer tank was rapidly losing pressure. They returned to the surface and opened the bunker to let the gas in. A few minutes later, the bunker exploded and sent the missile's warhead into the air.

After a day of searching, a 12-kiloton bomb was found a few hundred meters from the explosion site and picked up by the US military. The missile itself was the largest nuclear weapon in the US arsenal and could cause an explosion 600 times larger than in Hiroshima. Livingston was injured by the explosion and died shortly after arriving at the hospital. Another 21 people were also injured.

David Powell was later demoted for breaking protocol. Until that day, he did not consider himself guilty of what had happened. The government would later announce that human error was to blame.

Palomar H-bomb incident

On January 17, 1966, twelve B-52 bombers carried hydrogen bombs to Allied countries in Europe as part of a military exercise called Operation Chrome Dome. The goal was to prepare for the first encounter with the Soviet Union during the Cold War.

One of the bombers collided with the tanker KC-135, which was trying to refuel in the air over the southern coast of Spain. The accident caused both planes to be covered in fuel and burst into flames and exploded. Although a few people were able to parachute safely to the ground, seven were killed in the explosion. The wreckage of the planes fell on Palomares, a seaside farming village in southern Spain.

The local population did not realize that the debris would spread radioactive plutonium throughout the area, contaminating the land and water supply of the entire city. Three bombs were immediately recovered. The fourth could not be found for three months, right up to April 7, 1966.

For the first time in history, the US military showed the public a nuclear weapon. Checking the population revealed some traces of radiation, and rates of cancer were similar to those seen in other cities in the area. Since the discovery of soil contamination in 2006, the US government has finally agreed to help Spain rebuild. The issue was not resolved immediately.

Kyshtym nuclear incident

The Kyshtym incident ranks third on the list of the largest nuclear disasters. It took place in the city of Mayak in the Ural Mountains in the Soviet Union on September 29, 1957, at the height of the Cold War.

The Mayak plant produced six materials needed to develop weapons-grade plutonium. At that time, the USSR did not inform its workers about the serious possibility of radiation poisoning from radioactive materials.

At that time, the plant used the labor of local prisoners to dispose of waste, dumping them into the Techa River. Nearby residents did not know about the infection until one of the local men received serious burns and, as a result, the amputation of his legs.

Thyroid cancer rates in this region are now three times higher than in comparable areas. To this day, people there suffer from birth defects, radiation burns, and seven rare forms of cancer not commonly seen in the country's population.

The USSR gave no warning to people for years after the initial contamination, and Russian regulators did not maintain the plant or protect the civilian population. Plant technicians failed to notice a structural failure in one of the cooling systems, which set off a chain reaction.

On September 29, 1957, a cooling problem led to a massive explosion in one of the radioactive waste tanks. The explosion spread radioactive substances in the area where about 300,000 people lived.

The Soviet leadership evacuated only 10,000 people from the region. The rest were left to "watch". Declassified Russian documents later presented this as Muslyumov's experiment.

Many people living in this area are still fighting for the right to be resettled. Due to political ignorance and human error, the Lighthouse and its surrounding area is considered the most polluted place on Earth.

Tokaimur nuclear accident

A Japanese nuclear fuel reprocessing company has set up a reprocessing plant near Tokaimura to produce enriched uranium for the plant's nuclear reactor. Three technicians were assigned to prepare the fuel and fill the tank.

This type of fuel had not been produced at the plant for three years, and the technicians had no qualifications for the job. This lack of knowledge and experience led to one of the worst accidents in the history of industrial Japan.

The technicians unknowingly overfilled the sludge tank, which had a maximum capacity of 2.4 kilograms. When the mass reached a critical threshold, the tank was filled with 16 kilograms of uranium.

A negative reaction began, which produced a brief blue flash. All three technicians instantly received a lethal dose of radiation. The tank also began spewing radioactive substances yttrium-94 and barium-140 into the air above the plant.

The two technicians in charge died from radiation burns and exposure to gamma radiation. The rest of the team managed to empty the tank and replace the cooling materials with boric acid, which brought the uranium back to sub-critical levels. The civilians were evacuated within two days, and the Japanese authorities worked diligently to clear the area.

Accident at Windscale

The worst nuclear disaster in Europe occurred on October 10, 1957 in Cumbria, United Kingdom. The Windscale facility used a system of nuclear reactors that were controlled by graphite.

Built in 1951, the station was intended to produce atomic weapons for the British government. On the morning of October 8, 1957, station engineers noticed that one of the systems was cooling down and not up to operating temperature.

They used the Wigner cycle, which reused captured energy from the reactor to cool and heat the reactor. The test was successful. But two days later, the engineers noticed that the temperature in the reactor was again incorrect and decided to heat the reactor. They did not know that there was a fire in the first reactor. Using a system that pumped oxygen into the reactor, they simply fanned the fire.

The fire raged for three days. Conventional methods such as water could not be used as water is oxidized by radioactive materials and can cause even more damage to the structure.

Finally, the engineers realized that the fire would lose its oxygen supply if the hatch at the top of the first reactor's chimney was closed. So they did, and the fire was successfully stopped after 24 hours. There were no casualties.

However, later it turned out that some pollution did reach the UK and caused an increase in the level of thyroid cancer. The reactor has since been sealed and shut down, but the British government has ruled that the plant cannot be shut down completely until 2060.

B-52 case at Goldsboro

On January 24, 1961, a B-52 bomber with two Mk 39 atomic bombs of 4 megatons each was supposed to refuel over the Air Force Base. Seymour Johnson. The B-52 rendezvoused with an air tanker over Goldsboro in North Carolina northeast of the base.

The crew of the tanker noticed that the B-52 was oozing fuel from the right wing, and the bomber was ordered to return to base. On approach to the runway, a serious leak in the fuel tank caused serious mechanical damage, leaving the aircraft out of control at an altitude of 3,000 meters.

On landing, the plane broke apart and dropped two bombs into the environment. Three crew members died in the crash. The rest landed safely. The Air Force immediately dispatched search parties to look for the missing bombs.

Both bombs were quickly recovered. However, explosives experts found that one bomb passed three of the four stages of combat readiness. If these bombs did not have to be fired by the pilot on the plane before being sent, millions of people would die.

Fukushima accident

On March 11, 2011, an earthquake hit the coast of Japan. The tectonic movement from the initial earthquake caused a tsunami that headed straight for the Fukushima Daiichi nuclear plant.

The massive wave, which traveled at speeds of several hundred kilometers per hour, caused massive damage to the cooling and ventilation systems that are critical to temperature control in every reactor. This resulted in an immediate release of radioactivity.

After a month of assessing the damage to the local population, the Japanese government announced the creation of a 20-kilometer exclusion zone on April 19, 2011. Residents were evacuated and relocated. The government ordered the shutdown of all six reactors, and a year later they were completely shut down.

Today, this area is extremely polluted, and radiation continues to be emitted. The Japanese government has yet to find a solution.

Three Mile Island accident

On March 28, 1970, one of the worst nuclear disasters in US history occurred at the Three Mile Island nuclear facility in Pennsylvania. Plant workers did not notice that a mechanical failure in the cooling system caused a significant increase in core temperature in the reactor.

Unfortunately, there were no warning systems or sensors at this facility. Reactor workers turned off the coolant supply to the reactor, which overheated and half of its uranium core melted. Although there was a release of radiation, local residents were not affected.

The threat this plant poses to two million people has fueled protests by anti-nuclear activists. On April 1, 1979, President Jimmy Carter inspected the plant to ensure that action was being taken to prevent such an accident. For nearly forty years after that, Three Mile Island operated without further accidents. However, the plant is scheduled to be decommissioned in 2019 due to competitive prices for natural gas.

Chernobyl tragedy

The worst nuclear disaster that shook the entire planet occurred on April 26, 1986 at the Chernobyl nuclear power plant near Pripyat in the Soviet Union (now Ukraine). What should have been a routine safety test for the fourth reactor of the Chernobyl nuclear power plant has become a catastrophic meltdown.

The Soviet government provided a detailed list of instructions for workers to follow in order to perform the test safely. But one of the shifters decided to neglect the protocol and incorrectly followed the sequence when working with the core.

The intense heat from the core resulted in a massive release of steam, destroyed a third of the building, and released a lethal amount of radioactive material into the atmosphere, which carried the cloud to Asia and Europe. The first groups of firefighters literally had to fight with their bare hands with radioactive raw materials and a fire.

To this day, a molten pile of radioactive fallout lies under the core of the reactor. If you stand next to it for 30 seconds, you can get radioactive burns. If you stand for more than four minutes, there will be only a few days left to live.

Firefighters working in the fallout areas died from severe radiation burns in the local town of Pripyat. Their fire suits are still lying in the basement of the hospital, and the room they are in is one of the most irradiated places in the exclusion zone. The Russian government sent more than 500,000 rescuers to fight the accident. Many died, though not immediately.

50,000 people of the population of Pripyat had to be evacuated, people were allowed to take only valuable things. Nine months later, the Soviet Union sealed the reactor with a steel and concrete sarcophagus.

Although the area will be uninhabitable for the next 50,000 years, the Russian government did not close the station until the early 2000s.

Even today it is difficult to determine the extent of the damage caused by the accident at the Chernobyl nuclear power plant. Accident victims continue to suffer from high rates of thyroid cancer and birth defects. However, some manage to live in the exclusion zone.

On April 26, 1986, an explosion occurred at the 4th power unit of the Chernobyl Nuclear Power Plant (NPP). The reactor core was completely destroyed, the building of the power unit partially collapsed, and a significant release of radioactive materials into the environment occurred.

The resulting cloud carried the radionuclides over most of Europe and the Soviet Union.

Directly during the explosion, one person died, another died in the morning.

Subsequently, 134 employees of the nuclear power plant and rescue teams developed radiation sickness. 28 of them died during the following months.

Until now, this accident is considered the worst accident at a nuclear power plant in history.However, such stories happened not only on the territory of the former USSR.

Below are the top 10 worst accidents at nuclear power plants.

10. "Tokaimura", Japan, 1999

Level : 4
The accident at the nuclear facility "Tokaimura" occurred on September 30, 1999 and resulted in the death of three people.
At that time, it was the most serious accident in Japan related to the peaceful use of nuclear energy.
The accident happened at the small radiochemical plant of JCO, a division of Sumitomo Metal Mining, in Tokai Township, Naka County, Ibaraki Prefecture.
There was no explosion, but the result of the nuclear reaction was intense gamma and neutron radiation from the sump, which triggered an alarm, after which actions began to localize the accident.
In particular, 161 people were evacuated from 39 residential buildings within a radius of 350 meters from the enterprise (they were allowed to return to their homes after two days).
11 hours after the start of the accident, a gamma radiation level of 0.5 millisieverts per hour was recorded at one of the sites outside the plant, which is approximately 4167 times higher than the natural background.
Three workers who directly worked with the solution were heavily irradiated. Two died a few months later.
In total, 667 people were exposed to radiation (including plant workers, firefighters and rescuers, as well as local residents), but, with the exception of the three workers mentioned above, their radiation doses were insignificant.

9. Buenos Aires, Argentina, 1983

Level : 4
The RA-2 installation was located in Buenos Aires in Argentina.
A qualified operator, with 14 years of experience, was alone in the reactor hall and performed operations to change the configuration of the fuel.
The retarder was not drained from the tank, although this was required by the instructions. Instead of removing the two fuel cells from the tank, they were placed behind a graphite reflector.
The fuel configuration was complemented by two regulating elements without cadmium plates. Critical condition was evidently reached when the second of these was being set up, as it was found to be only partly submerged.
The burst of power gave from 3 to 4.5 × 1017 divisions, the operator received an absorbed dose of gamma radiation of about 2000 rad and 1700 rad of neutron radiation.
Irradiation was extremely uneven, the upper right side of the body was more irradiated. The operator lived after that for two days.
Two operators who were in the control room received doses of 15 rad of neutron and 20 rad of gamma radiation. Six others received smaller doses of about 1 rad, and nine more received less than 1 rad.

8. Saint Laurent, France, 1969

Level : 4
The first gas-cooled uranium-graphite reactor of the UNGG type at the Saint Laurent nuclear power plant was put into operation on March 24, 1969. Six months later, one of the most serious incidents occurred at nuclear power plants in France and the world.
50 kg of uranium placed in the reactor began to melt. The event was classified as Grade 4 on the International Nuclear Event Scale (INES), making it the most serious incident in the history of French nuclear power plants.
As a result of the accident, about 50 kg of molten fuel remained inside the concrete case, so the leakage of radioactivity outside it was insignificant and no one was injured, but it was necessary to shut down the unit for almost a year to clean the reactor and improve the refueling machine.

7. NPP SL-1, USA, Idaho, 1961

Level : 5
SL-1 is an American experimental nuclear reactor. It was developed by order of the US Army, for the power supply of isolated radar stations beyond the Arctic Circle and for the line of early radar detection.
The development was carried out as part of the Argonne Low Power Reactor (ALPR) program.
On January 3, 1961, a control rod was removed at the reactor during work for unknown reasons, an uncontrolled chain reaction began, the fuel heated up to 2000 K, and a thermal explosion occurred that killed 3 employees.
This is the only radiation accident in the United States that resulted in the immediate death of people, the meltdown of the reactor and the release of 3 TBq of radioactive iodine into the atmosphere.

6. Goiania, Brazil, 1987

Level : 5
In 1987, a part from a radiotherapy unit containing the radioactive isotope cesium-137 in the form of cesium chloride was stolen from an abandoned hospital by looters, after which it was thrown away.
But after some time, it was discovered in a landfill and attracted the attention of the owner of the landfill, Devar Ferreira, who then brought the found medical source of radioactive radiation to his house and invited neighbors, relatives and friends to look at the glowing blue powder.
Small fragments of the source were picked up, rubbed on the skin, passed on to other people as gifts, and as a result, the spread of radioactive contamination began.
For more than two weeks, more and more people came into contact with powdered cesium chloride, and none of them knew about the danger associated with it.
As a result of the widespread distribution of highly radioactive powder and its active contact with various objects, a large amount of material contaminated with radiation accumulated, which was later buried in the hilly area of ​​one of the suburbs of the city, in the so-called near-surface storage.
This area can only be used again after 300 years.

5. NPP Three Mile Island, USA, Pennsylvania, 1979

Level : 5
The accident at the Three Mile Island nuclear power plant is the largest accident in the history of commercial nuclear energy in the United States, which occurred on March 28, 1979 at the second power unit of the station due to a leak of the primary coolant of the reactor plant that was not detected in a timely manner and, accordingly, the loss of nuclear fuel cooling.
During the accident, about 50% of the reactor core melted, after which the power unit was never restored.
The premises of the nuclear power plant were subjected to significant radioactive contamination, but the radiation consequences for the population and the environment turned out to be insignificant. The accident was assigned level 5 on the INES scale.
The accident exacerbated an already existing crisis in the US nuclear industry and caused a surge in anti-nuclear sentiment in society.
Although all this did not immediately stop the growth of the US nuclear energy industry, its historical development was stopped.
After 1979 and until 2012, no new licenses for the construction of nuclear power plants were issued, and the commissioning of 71 previously planned plants was canceled.

4. Windscale, UK, 1957

Level : 5
The Windscale accident is a major radiation accident that occurred on October 10, 1957 at one of the two reactors of the Sellafield nuclear complex, in Cumbria, northwest England.
As a result of a fire in an air-cooled graphite reactor for the production of weapons-grade plutonium, a large (550-750 TBq) release of radioactive substances occurred.
The accident is level 5 on the International Nuclear Event Scale (INES) and is the largest in the history of the UK nuclear industry.

3. Kyshtym, Russia, 1957

Level : 6
The "Kyshtym accident" is the first man-made radiation emergency in the USSR that occurred on September 29, 1957 at the Mayak chemical plant located in the closed city of Chelyabinsk-40 (now Ozyorsk).
September 29, 1957 at 4:2 pm2 due to the failure of the cooling system, an explosion of a 300 cu. m, which contained about 80 cubic meters. m of highly radioactive nuclear waste.
The explosion, estimated at tens of tons of TNT, destroyed the tank, the concrete floor 1 m thick and weighing 160 tons was thrown aside, about 20 million curies of radioactive substances were released into the atmosphere.
Part of the radioactive substances was raised by the explosion to a height of 1-2 km and formed a cloud consisting of liquid and solid aerosols.
Within 10-12 hours, radioactive substances fell out over a distance of 300-350 km in the northeast direction from the explosion site (in the direction of the wind).
The territory of several enterprises of the Mayak plant, a military camp, a fire department, a colony of prisoners, and then an area of ​​​​23 thousand square meters turned out to be in the zone of radiation contamination. km with a population of 270 thousand people in 217 settlements of three regions: Chelyabinsk, Sverdlovsk and Tyumen.
Chelyabinsk-40 itself was not damaged. 90% of radiation pollution fell on the territory of the Mayak chemical plant, and the rest dissipated further.

2. NPP "Fukushima", Japan, 2011

Level : 7
The accident at the Fukushima-1 nuclear power plant is a major radiation accident of the maximum level 7 on the International Nuclear Event Scale, which occurred on March 11, 2011 as a result of the strongest earthquake in the history of Japan and the tsunami that followed it.
The earthquake and tsunami hit disabled external power supplies and backup diesel generators, which caused the inoperability of all normal and emergency cooling systems and led to the melting of the reactor core at power units 1, 2 and 3 in the first days of the accident.
A month before the accident, the Japanese authorities approved the operation of power unit No. 1 for the next 10 years.
In December 2013, the nuclear power plant was officially closed. On the territory of the station, work is underway to eliminate the consequences of the accident.
Japanese nuclear engineers estimate that bringing the facility to a stable, safe state could take up to 40 years.
Financial damage, including cleanup costs, decontamination and compensation costs, is estimated at $189 billion as of 2017.
Since the work to eliminate the consequences will take years, the amount will increase.

1. Chernobyl nuclear power plant, USSR, 1986

Level : 7
Chernobyl disaster - the destruction on April 26, 1986 of the fourth power unit of the Chernobyl nuclear power plant, located on the territory of the Ukrainian SSR (now - Ukraine).
The destruction was explosive, the reactor was completely destroyed, and a large amount of radioactive substances was released into the environment.
The accident is regarded as the largest of its kind in the history of nuclear energy, both in terms of the estimated number of people killed and affected by its consequences, and in terms of economic damage.
During the first three months after the accident, 31 people died; long-term effects of exposure, identified over the next 15 years, caused the death of 60 to 80 people.
134 people suffered from radiation sickness of varying severity.
More than 115 thousand people from the 30-kilometer zone were evacuated.
Significant resources were mobilized to eliminate the consequences, more than 600 thousand people participated in the liquidation of the consequences of the accident.

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