Kyshtym
Encyclopedia
Chelyabinsk Oblast
-External links:*...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
, located on the eastern slopes of the South Ural Mountains
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...
90 kilometres (55.9 mi) northwest of Chelyabinsk
Chelyabinsk
Chelyabinsk is a city and the administrative center of Chelyabinsk Oblast, Russia, located in the northwestern side of the oblast, south of Yekaterinburg, just to the east of the Ural Mountains, on the Miass River. Population: -History:...
, near the town of Ozyorsk
Ozyorsk, Chelyabinsk Oblast
Ozyorsk or Ozersk is a closed town in Chelyabinsk Oblast, Russia. Population: It was founded on the shore of the Irtyash Lake in 1945...
. Population: 36,000 (1970).
History
It was established by the Demidovs in 1757 around two factories for production of cast iron and steel. It was granted town status in 1934.Nuclear disaster
Kyshtym is near the Chelyabinsk-40 nuclear complex, also known as "MayakMayak
Mayak Production Association refers to an industrial complex that is one of the biggest nuclear facilities in the Russian Federation. It housed plutonium production reactors and a reprocessing plant...
" ("lighthouse" in Russian), where on September 29, 1957, a violent explosion involving dry nitrate and acetate salts in a waste tank containing highly radioactive waste, contaminated an area of more than 15,000 square kilometers (Ozyorsk was the town built around the Mayak combine, but it was a closed city
Closed city
A closed city or closed town is a settlement with travel and residency restrictions in the Soviet Union and some of its successor countries. In modern Russia, such places are officially known as "closed administrative-territorial formations" ....
, which was not marked on maps, thus making Kyshtym the nearest town to the location of the disaster). The explosion resulted from a failure of the cooling system of the tank.
There was a release of 740 PBq
Becquerel
The becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
of fission product
Fission product
Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The...
s, approximately 10% of which was dispersed into the atmosphere. Cerium-144
Isotopes of cerium
Naturally occurring cerium is composed of 4 stable isotopes: 136Ce, 138Ce, 140Ce, and 142Ce with 140Ce being the most abundant ; 136Ce, 138Ce, and 142Ce are predicted to undergo double beta decay but this process has never been observed...
and Zirconium-95
Isotopes of zirconium
Naturally occurring zirconium is composed of four stable isotopes , and one very long-lived radioisotope , a primordial nuclide that decays via double beta decay with an observed half-life of 2.0×1019 years; it can also undergo single beta decay which is not yet observed, but the theoretically...
(both relatively short lived isotopes with a half life of 285 and 64 days respectively) made up 91% of the release. There was 1 PBq of Sr-90
Strontium-90
Strontium-90 is a radioactive isotope of strontium, with a half-life of 28.8 years.-Radioactivity:Natural strontium is nonradioactive and nontoxic, but 90Sr is a radioactivity hazard...
, and 13 TBq of Cs-137
Caesium-137
Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
. The contaminated zone, called East Urals Radioactive Trace (EURT), measuring 300 x 50 km was contaminated by more than 4 kBq/m² of Sr-90. The global fallout of Sr-90 was about 2 kBq/m². An area measuring 17 km² was contaminated by about 100 MBq Sr-90/m².
There were 270,000 inhabitants of the area. Mass evacuation was carried out as the critical contamination resulted from Sr-90 with a half-life of 28.8 years. About 800 km² of land were taken out of use, and 82% of this area has now been taken into use again for forestry and farming. However, evacuation was limited to the nearest settlements leading to more than 1000 acknowledged victims. It was estimated in 1990 that at this time, around 10,000 people lived in areas where the level of ambient radiation was more than quadruple that of the average in Chernobyl's restricted area after 1986.
The Kyshtym accident was largely concealed by the Soviet government until 1980, when the Soviet biologist Zhores Medvedev
Zhores Medvedev
Zhores Aleksandrovich Medvedev is a Russian biologist, historian and dissident. His twin brother is the historian Roy Medvedev.-Biography:Zhores Medvedev and his twin brother Roy Medvedev were born on 14 November 1925 in Tbilisi, Georgia, USSR....
revealed its existence.