Kyshtym disaster

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Kyshtym disaster

Map of the East Urals Radioactive Trace (EURT): area contaminated by the Kyshtym disaster.
Native name	Кыштымская авария
Date	29 September 1957
Time	11:22 UTC
Location	Mayak, Chelyabinsk-40, Chelyabinsk Oblast, Russian SFSR, Soviet Union
Coordinates	55°42′45″N 60°50′53″E / 55.71250°N 60.84806°E / 55.71250; 60.84806
Also known as	Mayak disaster or Ozyorsk disaster
Type	Nuclear accident
Outcome	INES Level 6 (serious accident)
Casualties
270,000 affected. 10,000–12,000 evacuated. At least 200 people died of radiation sickness[1][2] 66 diagnosed cases of chronic radiation syndrome[3]

The Kyshtym disaster, sometimes referred to as the Mayak disaster or Ozyorsk disaster in newer sources, was a radioactive contamination accident that occurred on 29 September 1957 at Mayak, a plutonium production site for nuclear weapons and nuclear fuel reprocessing plant located in the closed city of Chelyabinsk-40 (now Ozyorsk) in Chelyabinsk Oblast, Russian SFSR, Soviet Union.

The disaster is the second worst nuclear incident by radioactivity released, after the Chernobyl disaster and was regarded as the worst nuclear disaster in history until Chernobyl.^[4] It is the only disaster classified as Level 6 on the International Nuclear Event Scale (INES),^[5] which ranks by population impact, making it the third-worst after the two Level 7 events: the Chernobyl disaster, which resulted in the evacuation of 335,000 people, and the Fukushima Daiichi disaster, which resulted in the evacuation of 154,000 people. At least 22 villages were exposed to radiation from the Kyshtym disaster, with a total population of around 10,000 people evacuated. Some were evacuated after a week, but it took almost two years for evacuations to occur at other sites.^[6]

The disaster spread hot particles over more than 52,000 square kilometres (20,000 sq mi), where at least 270,000 people lived.^[7] Since Chelyabinsk-40 (later renamed Chelyabinsk-65 until 1994) was not marked on maps, the disaster was named after Kyshtym, the nearest known town.