Posted on October 21, 2020October 19, 2020 by PaulContest #678 Hint What happened here eventually impacted an area of 20,000 KM2
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Кыштымская авария (или Кыштымская катастрофа) — первая в СССР радиационная чрезвычайная ситуация техногенного характера, возникшая 29 сентября 1957 года на химкомбинате «Маяк», расположенном в закрытом городе Челябинск-40 (ныне Озёрск). Авария относится к тяжёлой по последствиям, по современной международной классификации относится к 6 уровню из 7 возможных и занимает 3-е место, уступая лишь авариям на АЭС Чернобыльской и Фукусима-1, возникшим значительно позднее.
The Kyshtym disaster 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 accident 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 twenty-two 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 two years for evacuations to occur at other sites.
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.
After World War II, the Soviet Union lagged behind the United States in the development of nuclear weapons, so it started a rapid research and development program to produce a sufficient amount of weapons-grade uranium and plutonium. The Mayak plant was built in haste between 1945 and 1948. Gaps in physicists’ knowledge about nuclear physics at the time made it difficult to judge the safety of many decisions.
Environmental concerns were not taken seriously during the early development stage. Initially Mayak was dumping high-level radioactive waste into a nearby river, which flowed to the river Ob, flowing farther down to the Arctic Ocean. All six reactors were on Lake Kyzyltash and used an open-cycle cooling system, discharging contaminated water directly back into the lake. When Lake Kyzyltash quickly became contaminated, Lake Karachay was used for open-air storage, keeping the contamination a slight distance from the reactors but soon making Lake Karachay the “most-polluted spot on Earth”.
A storage facility for liquid nuclear waste was added around 1953. It consisted of steel tanks mounted in a concrete base, 8.2 meters (27 ft) underground. Because of the high level of radioactivity, the waste was heating itself through decay heat (though a chain reaction was not possible). For that reason, a cooler was built around each bank, containing twenty tanks. Facilities for monitoring operation of the coolers and the content of the tanks were inadequate. The accident involved waste which was from the sodium uranyl acetate process used by the early Soviet nuclear industry to recover plutonium from irradiated fuel; this is discussed by Foreman in his review on nuclear accidents. The acetate process is a special process which was never used in the West; the idea is to dissolve the fuel in nitric acid, alter the oxidation state of the plutonium, and then add acetic acid and base. This converts the uranium and plutonium into a solid acetate salt.
In 1957 the cooling system in one of the tanks containing about 70–80 tons of liquid radioactive waste failed and was not repaired. The temperature in it started to rise, resulting in evaporation and a chemical explosion of the dried waste, consisting mainly of ammonium nitrate and acetates (see ammonium nitrate–fuel oil bomb). The explosion, on 29 September 1957, estimated to have had a force of about 70–100 tons of TNT, threw the 160-ton concrete lid high into the air. There were no immediate casualties as a result of the explosion, but it released an estimated 20 MCi (800 PBq) of radioactivity. Most of this contamination settled out near the site of the accident and contributed to the pollution of the Techa River, but a plume containing 2 MCi (80 PBq) of radionuclides spread out over hundreds of kilometers. Previously contaminated areas within the affected area include the Techa river, which had previously received 2.75 MCi (100 PBq) of deliberately dumped waste, and Lake Karachay, which had received 120 MCi (4,000 PBq).
In the next ten to eleven hours, the radioactive cloud moved towards the north-east, reaching 300–350 km (190–220 mi) from the accident. The fallout of the cloud resulted in a long-term contamination of an area of more than 800 to 20,000 km2 (310 to 7,720 sq mi), depending on what contamination level is considered significant, primarily with caesium-137 and strontium-90. This area is usually referred to as the East-Ural Radioactive Trace (EURT).
Village Population Evacuation time (days) Mean effective dose equivalent (mSv)
Berdyanish 421 7–17 520
Satlykovo 219 7–14 520
Galikayevo 329 7–14 520
Rus. Karabolka 458 250 440
Alabuga 486 255 120
Yugo-Konevo 2,045 250 120
Gorny 472 250 120
Igish 223 250 120
Troshkovo 81 250 120
Boyovka 573 330 40
Melnikovo 183 330 40
Fadino 266 330 40
Gusevo 331 330 40
Mal. Shaburovo 75 330 40
Skorinovo 170 330 40
Bryukhanovo 89 330 40
Krivosheino 372 670 40
Metlino 631 670 40
Tygish 441 670 40
Chetyrkino 278 670 42
Klyukino 346 670 40
Kirpichiki 160 7–14 5
Because of the secrecy surrounding Mayak, the populations of affected areas were not initially informed of the accident. A week later, on 6 October 1957, an operation for evacuating 10,000 people from the affected area started, still without giving an explanation of the reasons for evacuation.
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 eighteen years later, in 1976, 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 Lev Tumerman, former head of the Biophysics Laboratory at the Engelhardt Institute of Molecular Biology in Moscow.
The true number of fatalities remains uncertain because radiation-induced cancer is clinically indistinguishable from any other cancer, and its incidence rate can be measured only through epidemiological studies. One book claims that “in 1992, a study conducted by the Institute of Biophysics at the former Soviet Health Ministry in Chelyabinsk found that 8,015 people had died within the preceding 32 years as a result of the accident”. By contrast, only 6,000 death certificates have been found for residents of the Techa riverside between 1950 and 1982 from all causes of death, though perhaps the Soviet study considered a larger geographic area affected by the airborne plume. More recent epidemiological studies suggest that around 49 to 55 cancer deaths among riverside residents can be associated to radiation exposure. This would include the effects of all radioactive releases into the river, 98% of which happened long before the 1957 accident, but it would not include the effects of the airborne plume that was carried north-east. The area closest to the accident produced 66 diagnosed cases of chronic radiation syndrome, providing the bulk of the data about this condition.
Ozyorsk in 2008.
To reduce the spread of radioactive contamination after the accident, contaminated soil was excavated and stockpiled in fenced enclosures that were called “graveyards of the earth”. The Soviet government in 1968 disguised the EURT area by creating the East Ural Nature Reserve, which prohibited any unauthorised access to the affected area.
According to Gyorgy, who invoked the Freedom of Information Act to gain access to the relevant Central Intelligence Agency (CIA) files, the CIA had known of the 1957 Mayak accident since 1959, but kept it secret to prevent adverse consequences for the fledgling American nuclear industry. Starting in 1989 the Soviet government gradually declassified documents pertaining to the disaster.
The level of radiation in Ozyorsk, at about 0.1 mSv a year, is harmless, but the area of the EURT is still heavily contaminated with radioactivity.
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