Kyshtym disaster - Wikipedia
The Kyshtym disaster was a radioactive contamination accident that occurred on 29 September 1957 at Mayak, a plutonium production site in Russia for nuclear weapons
and nuclear fuel reprocessing plant of the Soviet Union.
The event occurred in Ozyorsk, Chelyabinsk Oblast, a closed city built around the Mayak plant. It measured as a Level 6 disaster on the International Nuclear Event Scale (INES), making it the third-most serious nuclear accident ever recorded, behind the Fukushima Daiichi nuclear disaster and the Chernobyl disaster (both Level 7 on the INES). At least 22 villages were exposed to radiation from the disaster, with a total population of around 10,000 people evacuated. Some were evacuated after a week, but it took almost 2 years for evacuations to occur at other sites.
Vague reports of a "catastrophic accident" causing "radioactive fallout over the Soviet and many neighboring states" began appearing in the western press between 13 and 14 April 1958, and the first details emerged in the Viennese paper Die Presse on 17 March 1959. But it was only in 1976 (18 years after) that Soviet dissident Zhores Medvedev made the nature and extent of the disaster known to the world. In the absence of verifiable information, exaggerated accounts of the disaster were given. 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". Medvedev's description of the disaster in the New Scientist was initially derided by Western nuclear industry sources, but the core of his story was soon confirmed by Professor Leo Tumerman, former head of the Biophysics Laboratory at the Engelhardt Institute of Molecular Biology in Moscow.
The disaster spread hot particles over more than 52,000 square kilometres (20,000 sq mi), where at least 270,000 people lived. Since Ozyorsk/Mayak (named Chelyabinsk-40, then Chelyabinsk-65, until 1994) was not marked on maps, the disaster was named after Kyshtym, the nearest known town.