On March 29, 2018, an accident occurred at a nuclear power plant in Romania. Although the company operating the station said the problem was electronics and had nothing to do with the power unit, this event led many to recall incidents that not only claimed human lives, but also caused serious environmental disasters. From this article you will learn which accidents at nuclear power plants are considered to be the largest in the history of our planet.
Chalk River NPP
The world's first major accident at a nuclear power plant occurred in December 1952 in Ontario, Canada. It was the result of a technical error by the maintenance 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, 3,800 cubic meters of water containing dangerous impurities were dumped near the Ottawa River.
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 there to anneal the 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 the staff, the process became uncontrollable. Too powerful energy release led to the reaction of metallic uranium fuel with air. The fire started. The first signal about a tenfold increase in the level of radiation at a distance of 800 m from the core was received on October 10 at 11:00.
After 5 hours, the fuel channels were inspected. Experts found that part of the fuel rods (capacities in which fission of radioactive nuclei occurs) heated up to a temperature of 1400 ° C. Their unloading turned out to be impossible, so by evening the fire spread to the rest of the channels, containing a total of about 8 tons of uranium. During the night, personnel attempted to cool the core using carbon dioxide. On the morning of October 11, it was decided to flood the reactor with water. This made it possible to transfer the nuclear power plant reactor to a cold state by October 12.
Consequences of the accident at Calder Hall Station
The activity of the release was mostly due to a radioactive isotope of artificial iodine, which has a half-life of 8 days. In total, according to scientists, 20,000 curies got into the environment. Long-term contamination was due to the presence outside the reactor of radiocesium with a radioactivity of 800 curies.
Fortunately, none of the staff received a critical dose of radiation and there were no casu alties.
Leningrad NPP
Accidents at nuclear power plants happen more often than we think. Fortunately, most of them do not involve the release into the atmosphere of such quantities of radioactive substances as to pose a serious danger to human he alth and the environment.
In particular, at the Leningrad Nuclear Power Plant, which has been operating since 1873 (construction began in 1967), there have been many accidents over the past 40 years. The most serious of these was an emergency situation that occurred on November 30, 1975. It was caused by the destruction of the fuel channel and led to radioactive releases. This accident at a nuclear power plant, located just 70 km from the historic center of St. Petersburg, highlighted the design flaws of the Soviet RBMK reactors. However, the lesson was in vain. Subsequently, many experts called the disaster at the Leningrad NPP the forerunner of the accident at the nuclear power plant in Chernobyl.
Three Mile Island NPP
This nuclear power plant, located in the US state of Pennsylvania, was launched in 1974. Five years later, one of the worst man-made disasters in US history occurred there.
The cause of the accident at the nuclear power plant on the island of Three Mile Island was a combination of several factors: technical malfunctions, violations of the rules of operation and repair work and errorsstaff.
As a result of all of the above, there was damage to the core of the nuclear reactor, including parts of the uranium fuel rods. Overall, about 45% of its components melted.
Evacuation
On March 30-31, panic began among the residents of the surrounding settlements. They began to leave with their families. The state authorities have decided to evacuate people living within a radius of 35 km from the nuclear power plant.
Panic moods were fueled by the fact that this accident at a nuclear power plant in the United States coincided with the screening of the film "China Syndrome" in cinemas. The picture told about a disaster at a fictitious nuclear power plant, which the authorities are doing their best to hide from the population.
Consequences
Fortunately, this accident did not result in a meltdown of the reactor and/or the release of a catastrophic amount of radioactive substances into the atmosphere. The safety system was triggered, which is a containment in which the reactor was enclosed.
As a result of the accident, no one received serious injuries, high doses of radiation and no deaths. 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 onslaught of its activists, over time, the authorities had to abandon the construction of new power units. In particular, 50 of the nuclear facilities under construction in the United States at that time were mothballed.
Remediation
For the complete completion of work onit took 24 years and US$975 million to clean up the aftermath of the accident. This is 3 times higher than the insurance. Specialists decontaminated the working premises and territory of the nuclear power plant, unloaded nuclear fuel from the reactor, and the emergency second power unit was closed forever.
Saint-Laurent-des-Haut Nuclear Power Plant (France)
This nuclear power 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 block of the nuclear power plant, with a capacity of 500 MW, operating on natural uranium.
At 5:40 pm, the station's reactor automatically "cut down" due to a sharp increase in radioactivity. As was later clarified by IAEA experts and inspectors, corrosion of the structure of the fuel channels led to the melting of 2 fuel rods, which contained a total of 20 kg of uranium.
Consequences
It took 2 years 5 months to clean up the reactor. 500 people were involved in these works.
The emergency block SLA-2 was restored and returned to service only in 1983. However, 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.
The accident at the Chernobyl nuclear power plant in 1986
The nuclear power plant, located in the city of Pripyat, located on the border of the Ukrainian and Belarusian SSRs, began operating in 1970.
26April 1986 in the dead of night at the 4th power unit there was a strong explosion that completely destroyed the reactor. As a result, the building of the power unit and the roof of the turbine hall were also partially destroyed. There were about three dozen fires. The largest of them were on the roof of the engine room and the reactor room. Both by 2 hours and 30 minutes were suppressed by firefighters. By morning, there were no more fires left.
Consequences
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 died, another nuclear power plant employee died in the morning after the accident from his injuries. The next day, 104 victims were evacuated to hospital No. 6 in Moscow. Subsequently, 134 employees of the station, as well as some members of the rescue and fire teams, were diagnosed with radiation sickness. Of these, 28 died in the following months.
On April 27, the entire population of the city of Pripyat was evacuated, as well as residents of settlements located in a 10-kilometer zone. Then the exclusion zone was increased to 30 km.
On October 2 of the same year, the construction of the city of Slavutich began, in which the families of the employees of the Chernobyl nuclear power plant were settled.
Further work to mitigate the dangerous situation in the area of the Chernobyl disaster
On April 26, a fire broke out again in different parts of the central hall of the emergency block. Due to the severe radiation situation, its suppression by regular means was not carried out. For liquidationhelicopters were used to start the fire.
A government commission has been set up. The bulk of the work was completed during 1986-1987. In total, more than 240,000 servicemen and civilians took part in the liquidation of the consequences of the accident at the nuclear power plant in Pripyat.
In the first days after the accident, the main efforts were made to reduce radioactive releases and prevent the aggravation of an already dangerous radiation situation.
Preservation
It was decided to bury the destroyed reactor. This was preceded by the cleanup of the territory of the nuclear power plant. Then the debris from the roof of the machine room was removed inside the sarcophagus or poured with concrete.
At the next stage of work, a concrete "sarcophagus" was erected around the 4th block. To create it, 400,000 cubic meters of concrete were used, and 7,000 tons of metal structures were assembled.
The accident at the Fukushima nuclear power plant in Japan
This massive disaster happened 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 tremors, the power units of the station were automatically stopped. However, the ensuing tsunami, accompanied by giant waves and strong winds, led to the shutdown of the power supply to the nuclear power plant. In this situation, steam pressure began to rise sharply in all reactors,because the cooling system has shut down.
On the morning of May 12, a strong explosion occurred at the 1st power unit of the nuclear power plant. The radiation level immediately increased dramatically. 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 action to prevent a more serious disaster. Later, 130 more self-defense soldiers and firefighters joined them, as white smoke appeared above the 4th block, and there were fears that a fire had started there.
Worldwide concern has arisen over the consequences of the accident in Japan at the Fukushima nuclear power plant.
On April 11, another 7-magnitude earthquake shook the nuclear power plant. The power went out again, but this did not create any additional problems.
In mid-December, 3 problematic reactors were transferred to a cold shutdown. However, in 2013, the station experienced a serious leak of radioactive substances.
At the moment, according to Japanese experts, in the vicinity of Fukushima, the radiation background is equal to the natural one. However, it remains to be seen what the consequences of the accident at the nuclear power plant will be for the he alth of future generations of the Japanese, as well as representatives of the Pacific flora and fauna.
Accident at a nuclear power plant in Romania
And 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 he alth of NPP personneland residents of nearby communities. However, this is already the second emergency at the station in Chernavoda. On March 25, the 1st block was switched off there, and the 2nd worked only at 55% of its capacity. This situation has also caused concern to the Prime Minister of Romania, who has instructed to investigate these incidents.
Now you know the most serious accidents at nuclear power plants in the history of mankind. It remains to be hoped that this list will not be replenished, and the description of any accident of a nuclear power plant in Russia will never be added to it.
