The Kyshtym disaster was a radiation contamination incident that occurred on 29 September 1957 at Mayak, a nuclear fuel reprocessing plant in Russia (then a part of the Soviet Union). It measured as a Level 6 disaster on the International Nuclear Event Scale, making it the third most serious nuclear accident ever recorded (after the Chernobyl disaster, and Fukushima Daiichi nuclear disaster, both Level 7 on the INES scale). The event occurred in the town of Ozyorsk, a closed city built around the Mayak plant. Since Ozyorsk/Mayak (also known as Chelyabinsk-40 and Chelyabinsk-65) was not marked on maps, the disaster was named after Kyshtym, the nearest known town.
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After World War II, the Soviet Union lagged behind the United States in development of nuclear weapons, so it started a rapid research and development program to produce a sufficient amount of weapons-grade uranium and plutonium. The Mayak plant was built in a great hurry between 1945 and 1948. Gaps in Soviet physicists' knowledge about nuclear physics at the time made it difficult to judge the safety of many decisions. Also, environmental concerns were not taken seriously during the early development stage. All six reactors were on Lake Kyzyltash and used an open cycle cooling system, discharging irradiated water directly back into the lake. [1] Initially Mayak was dumping high-level radioactive waste into a nearby river, which was taking waste to the river Ob, flowing further down to the Arctic Ocean. Later on, Lake Karachay was used for open-air storage.[2]
A storage facility for liquid nuclear waste was added around 1953. It consisted of steel tanks mounted in a concrete base, 8.2 meters underground. Because of the high level of radioactivity, the waste was heating itself through decay heat (though a chain reaction was not possible). For that reason, a cooler was built around each bank containing 20 tanks. Facilities for monitoring operation of the coolers and the content of the tanks were not adequate.[3]
In September 1957, the cooling system in one of the tanks containing about 70–80 tons of liquid radioactive waste failed and was not repaired. The temperature in it started to rise, resulting in evaporation and a chemical explosion of the dried waste, consisting mainly of ammonium nitrate and acetates (see ammonium nitrate bomb). The explosion, estimated to have a force of about 70–100 tons of TNT threw the concrete lid, weighing 160 tons, into the air.[3] There were no immediate casualties as a result of the explosion, which released an estimated 2 to 50 MCi (74 to 1850 PBq) of radioactivity.[2][4][5]
In the next 10 to 11 hours, the radioactive cloud moved towards the northeast, reaching 300–350 kilometers from the accident. The fallout of the cloud resulted in a long-term contamination of an area of more than 800 square kilometers, primarily with caesium-137 and strontium-90.[2] This area is usually referred to as the East-Ural Radioactive Trace (EURT).[6]
Because of the secrecy surrounding Mayak, the populations of affected areas were not initially informed of the accident. A week later (on 6 October) an operation for evacuating 10,000 people from the affected area started, still without giving an explanation of the reasons for evacuation. People "grew hysterical with fear with the incidence of unknown 'mysterious' diseases breaking out. Victims were seen with skin 'sloughing off' their faces, hands and other exposed parts of their bodies."[7]
Although vague reports of a "catastrophic accident" began appearing in the western press in April 1958, it was only in 1976 that Zhores Medvedev made the nature and extent of the disaster known to the world.[8][9]
Even though the Soviet government suppressed information about the figures, it is estimated that the direct exposure to radiation caused at least 200 cases of death from cancer.[10] "In 1992, a study conducted by the Institute of Biophysics at the former Soviet Health Ministry in Chelyabinsk found that 8,015 people had died within the preceding 32 years as a result of the accident."[1]
To reduce the spread of radioactive contamination after the accident, contaminated soil was excavated and stockpiled in fenced enclosures that were called "graveyards of the earth".[11]
The Soviet government in 1968 disguised the EURT area by creating the East-Ural Nature Reserve, which prohibited any unauthorised access to the affected area.
Rumours of a nuclear mishap somewhere in the vicinity of Chelyabinsk had long been circulating in the West. That there had been a serious nuclear accident east of the Urals was eventually demonstrated by Zhores Medvedev, who, after his reference to the disaster in a western publication was derided by western nuclear industry sources, showed that numerous Soviet scientific publications on the effects of radiation on plant life, supposedly derived from laboratory experiments, were in fact thinly disguised descriptions of the area contaminated by the disaster.[12]
According to Gyorgy,[13] who invoked the Freedom of Information Act to gain access to the relevant Central Intelligence Agency (CIA) files, the CIA knew of the 1957 Mayak accident all along, but kept it secret to prevent adverse consequences for the fledgling American nuclear industry. In 1990 the Soviet government declassified documents pertaining to the disaster.[14][15]
The level of radiation in Ozyorsk itself is claimed to be safe for humans, but the area of EURT is still heavily contaminated with radioactivity.[10]