The Kyshtym Disaster

The Kyshtym disaster, also known as the Mayak disaster or the Ozyorsk disaster in newer sources, occurred on September 29, 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 third-worst nuclear incident in terms of radioactivity released, following the Chernobyl and Fukushima Daiichi disasters. It was classified as a Level 6 disaster on the International Nuclear Event Scale (INES), ranking third (in terms of population impact) behind 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; the Chernobyl disaster and the Fukushima Daiichi disaster are both classified as Level 7 disasters on the INES. The Kyshtym disaster exposed at least 22 villages to radiation, with a total population of around 10,000 people evacuated. Some were evacuated within a week, but it took nearly two years for others to be evacuated.

The disaster spread hot particles over more than 52,000 square kilometres (20,000 sq mi), where at least 270,000 people lived. Since Chelyabinsk-40 (later renamed Chelyabinsk-65 until 1994) was not marked on maps, the disaster was named after Kyshtym, the nearest known town. This is one of the historical disasters that people tried to cover up you should know.

Native name: Кыштымская авария
Date: 29 September 1957
Time: 11:22 UTC
Location: Mayak, Chelyabinsk-40, Chelyabinsk Oblast, Russian SFSR, Soviet Union
Deaths: 200
Also known as: Mayak disaster or Ozyorsk disaster
Type: Nuclear accident
Outcome: INES Level 6 (serious accident)