On March 29, 2018, an accident occurred at a nuclear power plant in Romania. Although the company operating the plant reported that the problem was related to electronics and has nothing to do with the power unit, this event led many to recall incidents that not only claimed lives but also caused serious environmental disasters. From this article you will learn what accidents at nuclear power plants are considered to be the largest in the history of our planet.
Cholk River NPP
The world's first major nuclear power plant accident occurred in December 1952 in Ontario, Canada. It was the result of a technical error of the personnel of the Chalk River NPP, which resulted in overheating and partial melting of its core. The environment was contaminated with radioactive products. In addition, near the Ottawa River there was a discharge of 3800 cubic meters of water containing hazardous impurities.
Windscale accident
The Calder Hall Nuclear Power Plant , located in the northwest of England, was built in 1956. It became the first nuclear power plant operated in a capitalist country. On October 10, 1957, planned work was carried out to anneal graphite masonry. This process was carried out to release the energy accumulated in it. Due to the lack of necessary instrumentation, as well as errors made by personnel, the process became uncontrollable. Too powerful energy release led to the reaction of metallic uranium fuel with air. The fire started. The first signal of a ten-fold increase in the level of radiation at a distance of 800 m from the core arrived on October 10 at 11:00.
After 5 hours, the fuel channels were inspected. Experts have found that part of the fuel rods (capacities in which fission of radioactive nuclei takes place) heated up to a temperature of 1400 ° C. Their unloading was impossible, so by evening the fire spread through the remaining channels, containing a total of about 8 tons of uranium. At night, the staff tried to cool the core using carbon dioxide. On the morning of October 11, it was decided to flood the reactor with water. This allowed by October 12 to put the reactor in a cold state.
Consequences of the accident at Calder Hall Station
The ejection activity was mainly attributed to the radioactive isotope of artificial iodine, which has a half-life of 8 days. In total, according to scientists, 20,000 curies fell into the environment. Long-term infection was a consequence of the presence of cesium with a radioactivity of 800 curies outside the reactor.
Fortunately, none of the staff received a critical dose of radiation and there were no casualties.
Leningrad NPP
Accidents at nuclear power plants occur much more often than we think. Fortunately, most of them are not associated with the release of such an amount of radioactive substances into the atmosphere as to pose a serious danger to human health and the environment.
In particular, at the Leningrad Nuclear Power Plant, operating since 1873 (the beginning of construction - 1967), over the past 40 years there have been many accidents. The most serious of these was the contingency that occurred on November 30, 1975. It was caused by the destruction of the fuel channel and led to radioactive emissions. This accident at a nuclear power plant located just 70 km from the historical center of St. Petersburg highlighted the design flaws of the RBMK Soviet reactors. However, the lesson was in vain. Subsequently, many experts called the disaster at Leningrad NPP the forerunner of the accident at the Chernobyl nuclear power plant.
Three Mile Island Nuclear Power Plant
This nuclear power plant, located in the US state of Pennsylvania, was launched in 1974. After 5 years, one of the most serious technological disasters in US history occurred there.
The cause of the accident at the nuclear power plant on Three Mile Island was a combination of several factors: technical malfunctions, violation of operating rules and repair work, and personnel errors.
As a result of all of the above, the core of the nuclear reactor, including parts of uranium fuel rods, was damaged. In general, about 45% of its components melted.
Evacuation
On March 30-31, a panic began among residents of the surrounding settlements. They began to leave whole families. The state authorities decided to evacuate people living within a radius of 35 km from the nuclear power plant.
The panic was fueled by the fact that this accident at a nuclear power plant in the United States coincided with the screening of the movie "Chinese Syndrome" in theaters. The picture was about a disaster at a fictitious nuclear power plant, which the authorities are trying hard to hide from the population.
Effects
Fortunately, as a result of this accident, the reactor did not melt and / or a catastrophic amount of radioactive substances was released into the atmosphere. The security system worked, which is a containment in which the reactor was enclosed.
As a result of the accident, no one received serious damage, a large dose of radiation and did not die. The release of radioactive particles was considered insignificant. Nevertheless, this accident caused a wide resonance in American society.
An anti-nuclear campaign has begun in the United States. Under the pressure of its activists, over time, the authorities had to abandon the construction of new power units. In particular, 50 of the nuclear facilities constructed at that time in the USA were mothballed.
Mitigation
It took 24 years and 975 million US dollars to complete the work on eliminating the consequences of the accident. This is 3 times higher than insurance. Specialists decontaminated the workrooms and the territory of the nuclear power plant, unloaded the nuclear fuel from the reactor, and the emergency second power unit was shut down forever.
NPP Saint-Laurent-des-O (France)
This nuclear plant, located on the banks of the Loire, 30 km from Orleans, was commissioned in 1969. The accident occurred in March 1980 at the 2nd unit of a nuclear power plant with a capacity of 500 MW operating on natural uranium.
At 17 hours and 40 minutes, the station’s reactor was automatically cut off due to a sharp increase in radioactivity. As it was subsequently ascertained by IAEA experts and inspectors, corrosion of the fuel channel structure led to the melting of 2 fuel elements, in which there were a total of 20 kg of uranium.
Effects
It took 2 years 5 months to clean the reactor. To carry out these works, 500 people were involved.
The emergency block SLA-2 was restored and returned to service only in 1983. However, but its capacity was limited to 450 MW. The block was finally closed in 1992, since the operation of this facility was recognized as economically inexpedient and constantly became the cause of protests by representatives of French environmental movements.
Accident at the Chernobyl nuclear power plant in 1986
A nuclear power plant located in the city of Pripyat, located on the border of the Ukrainian and Byelorussian SSR, began operating in 1970.
On April 26, 1986 , in the dead of night, a severe explosion occurred at the 4th power unit, which completely destroyed the reactor. As a result, the building of the power unit and the roof of the engine room were partially destroyed. About three dozen fires arose. The largest of them were on the roof of the engine room and reactor compartment. Both at 2 hours and 30 minutes were suppressed by firefighters. By morning, the centers of ignition were gone.
Effects
As a result of the Chernobyl accident, up to 380 million curies of radioactive substances were released.
During the explosion at the 4th power unit of the station, one person was killed, another NPP employee died in the morning after an accident from injuries. The next day, 104 injured were evacuated to hospital No. 6 in Moscow. Subsequently, 134 employees of the station, as well as some members of the rescue and fire brigades, were diagnosed with radiation sickness. Of these, 28 died in the following months.
April 27 evacuated the entire population of the city of Pripyat, as well as residents of settlements located in the 10-kilometer zone. Then the exclusion zone was increased to 30 km.
On October 2 of the same year, construction began on the city of Slavutich, in which the families of employees of the Chernobyl nuclear power plant were resettled.
Further work to mitigate the dangerous situation in the area of the Chernobyl disaster
On April 26, a fire broke out in different parts of the central hall of the emergency unit. Due to the difficult radiation situation, its suppression by regular means was not carried out. To eliminate the fire, helicopter equipment was used.
A government commission has been created. The bulk of the work was performed during 1986-1987. In total, more than 240,000 military personnel and civilians took part in the aftermath of the accident at the Pripyat nuclear power plant.
In the first days after the accident, the main efforts were made to reduce radioactive emissions and prevent the aggravation of the already dangerous radiation situation.
Conservation
It was decided to bury the destroyed reactor. This was preceded by the cleaning of the territory of the NPP. Then the debris from the roof of the machine room was removed inside the sarcophagus or flooded with concrete.
At the next stage of work, a concrete “sarcophagus” was erected around the 4th block. 400,000 cubic meters of concrete were used to create it, and 7,000 tons of metal structures were also installed.
Fukushima nuclear accident in Japan
This massive disaster occurred in 2011. The accident at the Fukushima nuclear power plant became the second after Chernobyl, which was assigned the 7th level on the international scale of nuclear events.
The uniqueness of this accident lies in the fact that it was preceded by an earthquake, recognized as the strongest in the history of Japan, and a devastating tsunami.
At the moment of shocks, the power units of the station were automatically stopped. However, the ensuing tsunami, accompanied by gigantic waves and strong winds, led to a power outage at the plant. In this situation, in all reactors, the vapor pressure began to increase sharply, since the cooling system was turned off.
On the morning of May 12, a strong explosion occurred at the 1st unit of the nuclear power plant. The radiation level immediately increased sharply. On March 14, the same thing happened at the 3rd power unit, and the next day - at the second. All personnel were evacuated from the nuclear power plant. Only 50 engineers remained there, who volunteered to take measures to prevent a more serious disaster. Later, another 130 soldiers of the self-defense forces and firefighters joined them, as white smoke appeared over the 4th block, and there were fears that a fire started there.
Concern has arisen around the world about the consequences of the Fukushima nuclear accident in Japan.
On April 11, another 7-magnitude earthquake shook the plant. The power supply turned off again, but this did not create additional problems.
In mid-December, 3 troubled reactors were put into a cold shutdown state. Nevertheless, in 2013, a serious leak of radioactive substances occurred at the station.
At the moment, according to the statement of Japanese experts, in the vicinity of Fukushima the radiation background is equal to the natural one. However, it is still unknown what the consequences of the accident at the nuclear power plant will be for the health of future generations of the Japanese, as well as representatives of the Pacific flora and fauna.
Romania nuclear accident
Now back to the information that started this article. The accident in Romania at a nuclear power plant was the result of a malfunction in the electrical system. The incident did not have any negative impact on the health of nuclear power plant personnel and residents of nearby settlements. However, this is the second emergency at the station in Cernavoda. On March 25, the 1st unit was disconnected, and the 2nd worked only at 55% of its capacity. This situation aroused concern among the Romanian Prime Minister, who instructed to investigate these incidents.
Now you know the most serious accidents at nuclear power plants in the history of mankind. It is hoped that this list will not be replenished, and a description of any accident at a nuclear power plant in Russia will never be added to it again.