Kyshtym disaster
The Kyschtym accident occurred on September 29, 1957 in the Nuclear plant Mayak (Russian производственное объединение " Маяк "), a plant for the industrial production of fissile material in the Soviet Union. As the only nuclear accident at level 6 on the International Nuclear Event Scale Rating (INES 6) it is the third most serious accident of history after the disasters of Chernobyl (1986) and Fukushima ( 2011), both of which are categorized as INES 7. In the event, very large amounts of radioactive substances were released.
Accident
The cost incurred in the preparation of spent uranium fuel rods to recover the fissile 239Pu highly radioactive liquid residues were stored in large tanks. This must be cooled because of the costs associated with the radioactive decay of substances decay heat. As the cooling lines of these 300 cubic-meter tanks had developed leaks during the year 1956 and the cooling failed, the contents began to dry this tank. On September 29, 1957, replaced the spark of an internal control device from an explosion of crystallized nitrate salts. It was a chemical ( not nuclear ) explosion, which released large quantities of radioactive materials. Among them were long-lived isotopes such as 90Sr (half-life 29 years ), 137Cs ( 30 years) and 239Pu ( 24,110 years ).
A total of matter with a radioactivity of 400 PBq (4 x 1017 Bq) over an area of about 20,000 square kilometers has been distributed by the accident, according to the production company Mayak and the authorities. The accident is comparable to the Chernobyl disaster in terms of the radioactivity of the released material. Other sources speak of much higher doses of radioactivity. Approximately 90 % of the radioactive material remaining on the premises, 10 % were by the wind up to 400 km in a north-easterly direction distributed ( Fallout ) and formed the so-called Osturalspur ( see figure).
The affected area of 20,000 km2 at that time had about 270,000 inhabitants. An approximately 1,000 km2, which was contaminated with more than 74 kBq per square meter with 90Sr, was evacuated seven to ten days later. Various sources speak 600-1200 affected. The average equivalent dose to the bone marrow of the 1,054 inhabitants of the three closest villages was about 570 mSv. Eight months later, another 6,500 people were taken to safety due to the contamination of their food. In total, about 10,700 people were resettled. A majority of these people has not been specifically medically monitored so that no firm conclusions about health effects to people from the evacuated areas can be made.
After the INES scale, the accident in 1957, an event the second highest category 6 dar. According to the Helmholtz Zentrum München, the effects of the accident have long been underestimated. According to recent estimates of the accident with INES 7 would have to be evaluated, it would thus be the first casualty of the highest level before the Chernobyl disaster.
In contrast to the Chernobyl disaster, the material was distributed locally to regionally. The intense graphite fire in Chernobyl carried a large part of radionuclides high up into the atmosphere, while at Mayak, due to lower thermals a ground-level cloud arose. The high concentration of radioactivity, lack of education of the population who are not widespread evacuation of the area and insufficient decontamination resulted in large losses in the affected region. An exact number of victims can not be specified, because no reliable studies and tests are available. A comparative analysis on the basis of designated by the authorities radioactive contamination comes out to about 1,000 additional cancer cases due to the accident.
Public perception
The explosion was reportedly still been hundreds of miles away visible as a brilliant glow and explained in the former Soviet newspapers as lightning or auroral according to witnesses reports. In later publications Zhores Aleksandrovich Medvedev described the process as " volcano -like explosion."
Due to the dismay of Western Europe and the associated extensive media coverage of the reactor fire in Chernobyl Chernobyl Disaster of 1986 is considered by many to be gravierendster nuclear accident since the Mayak accident did not reach to the public. The accident could be hushed up in the 1970s as the regional contamination was limited to the Urals and no measurable effects from fallout in Western Europe were detectable. The first information came through an article by Soviet journalists and dissidents Zhores Aleksandrovich Medvedev ( Жорес Александрович Медведев ) in the newspaper New Scientist, 1976 to the Western public. Published in 1979 Medvedev his reports and analyzes in the book report and analyzing previously undisclosed nuclear disaster in the Soviet Union, but was erroneously interpreted by a nuclear explosion from. The revelations of Medvedev were then questioned by western scientists. Medvedev himself suspected behind the interest to make nuclear power appear to be harmless, because at this time in many Western countries, nuclear power plants were built. The Soviet leadership acknowledged until 1989 is happening officially.
Contamination today
The accident put large amounts of radioactive material released. Also, in another incident in the 1967 radioactively contaminated sediment dusts were collected from the Lake Karachay by winds into the surrounding countryside, some of the material went down again in the affected already by the Kyschtym - accident areas. A scientific study of Russian and Norwegian government in 1997 came to the conclusion that since 1948 Mayak 90Sr and 137Cs with an activity of a total of 8.9 Exa - Becquerel ( AQR, 8.9 · 1018 Bq) were released into the environment. There are also emissions of other radioactive elements such as 239Pu. Evaluate the environmental organizations that were exposed by about 500,000 persons increased radiation doses.
Due to the radioactive exposure of workers and the general public through the operation of the plant will be forcibly performed there in recent years, studies on the effects of such radioactive burdens on people who have also worked because at Mayak compared to similar facilities above average number of women work respectively.
The radioactive contamination of the region since August 1, 2005 the subject of investigation international research project Southern Urals Radiation Risk Research ( SOUL ). Is coordinated by the Helmholtz Zentrum München.