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The Largest Nuclear Complex in the World “Mayak”
«Mayak» is a nuclear fuel reprocessing plant between the towns of Kasli and Kyshtym 72 km northwest of Chelyabinsk in Russia. The plant is located in the Ozersk central administrative territorial unit, formerly known as Chelyabinsk-40, later as Chelyabinsk-65, and the part of the Chelyabinsk Oblast.
The “Mayak” plant was built in 1945-48, in a great hurry and in total secrecy, as the part of the Soviet Union's nuclear weapon program. The plant's original mission was to make, refine, and machine plutonium for weapons. Five nuclear reactors were built for this purpose. Later the plant came to specialize in reprocessing plutonium from decommissioned weapons, and waste from nuclear reactors. Today the plant makes tritium and radioisotopes, but no plutonium. In recent years, proposals that the plant reprocess waste from foreign nuclear reactors have given rise to controversy. Now plans are being made to import 20,000 tones of nuclear waste in exchange for over 20 billion US dollars. Potential exporting countries include: Japan, South Korea, Taiwan, Bulgaria, Hungary, Switzerland, Germany and Spain. Russian authorities now hope to negotiate future reprocessing contracts with Switzerland, Spain, South Korea, Slovenia, Italy, Belgium, and Slovakia.
In the early years of its operation, the “Mayak” plant released quantities of radioactively contaminated water into several small lakes near the plant, and into the Techa river, the source of drinking water for many villages. It exposed 124,000 people to medium- and high levels of radiation.
Working conditions at “Mayak” resulted in severe health hazards and accidents. The most notable accident occurred on 29 September 1957, when the failure of the cooling system for a tank storing tens of thousands of tons of dissolved nuclear waste resulted in a non-nuclear explosion having a force estimated at about 75 tons of TNT, which released some 2 million Curies of radioactivity over 15,000 sq. miles. Some villagers were evacuated, but many were not. At least 272,000 people were affected by radiation. Hundreds of square miles were left barren and unusable for decades and maybe centuries. Today, around 7,000 people still live in direct contact with the highly polluted Techa river or on contaminated land.
Mayak Environmental Pollution
The Techa River
It is estimated that about 76 million cubic metres of radioactive waste was discharged into the open hydrographic drainage system connected to the Techa River in the period up to 1951. Since then the waste has been stored in an isolated reservoir on the plant's site at Karachai.
It is difficult to assess the severity of exposure to radiation experienced by the local population due to the high degree of secrecy surrounding the plant at the time. Epidemiological and medical
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One of Techensk Cascade dams. Picture from the website of Chelyabinsk State Television and Radio Company |
Picture from the website of Cheljabinsk State Television and Radio Company |
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Carriages and containers for radioactive materials transportation. Picture from the website of Chelyabinsk State Television and Radio Company |
research started later when recording began of the long-term affects of high level exposures to radiation on 124,000 residents. Around 7,500 people living along side the Techa River received significant radiation doses; those subsequently moved from 20 locations received doses of 0.03-1 Sv. The highest doses (up to 1.7 Gy) were received by the residents of the riverside village Metlino. According to official data there are 66 cases of chronic radiation sickness among the village's residents.
The radioactive waste has accumulated on the bottom of the river. The chain of polluted industrial reservoirs known as the Techen cascades occupies an area of about 70 square km and has a volume of about 380 million cubic meters.
Currently 90Sr and 137Cs are the main pollutants, while specific water activity in the basins is about 0.1-10 kBq/liter. The levels of silt pollution differ greatly from 1 up to 107 kBq/kilo. The Techa's floodplain areas (Asanovsk swamps), where silt pollution exceeds the allowable level, are ecologically dangerous.
The Karachai Lake
The polluted Karachai Lake, located on the plant's site, covers about an area of about a quarter of a square kilometre and has a volume of about 400,000 cubic metres. Currently the total radiation is estimated at 4.4 Ebq, with specific water activity of 90Sr и 137Cs being 0.06 and 0,4 GBq/liter, and soil 10 and 50 GBq/litre.
There is an estimated amount of underground water covering 30 square km with a volume of up to 4 million cubic metres. This has a high content of cesium and strontium.
Concrete panels shaped like upside-down glasses have been placed on the bottom of the lake to protect the lake's surface. From above the blocks have been covered with rocks. Currently about 70% of the reservoir's surface has been covered. A chain of drilling holes has been made around Karachai to enable continuous monitoring of soil and subsoil water pollution at various depths and distances.
The 1957 Explosion
Following the explosion at the plant in 1957, about 90 per cent of the radioactive material fell on the plant itself. The cloud, which had completely settled within 11 hours, left a trace 300 km long and between 30 and 50 km wide. This has been named the Eastern Ural Radioactive Trace (VURS). As a result of the accident about 23,000 sq km was exposed to radiation, including 217 homes. About 1,200 people were evacuated, mainly during the first day of the accident. They received radiation of 0.5 Gy. A further, 11,000 people were moved later. They received average doses of 0.2 Gy.
Radioactivity levels have now decreased 15 times since the half-life period is less than a year and most of the area was brought back within safety standards by 1982. Almost all of the land which received initial pollution of up to 4 Curie/km2 is currently being used for agriculture.
Research into radioactive ecology and biology is now being carried out in the remaining area, covering some 170 sq km, known as the Eastern Uralian Reserve. One of the world's largest centres of radiological research, a branch of the Biophysics Institute of the Russian Academy of Science, was established in Ozersk in 1953. Research has shown that the greatest impact on human health was in the early years of the plant's operation. This includes radiation sickness, high cancer rates, and thyroid gland disease in children.
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