Lake Karachay | |
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Lake type | Reservoir |
Lake Karachay (Russian: Карача́й), sometimes spelled Karachai, is a small lake in the southern Ural mountains in western Russia. Starting in 1951[1] the Soviet Union used Karachay as a dumping site for radioactive waste from Mayak, the nearby nuclear waste storage and reprocessing facility, located near the town of Ozyorsk (then called Chelyabinsk-40).
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According to a report by the Washington, D.C.-based Worldwatch Institute on nuclear waste, Karachay is the most polluted spot on Earth.[2] The lake accumulated some 4.44 exabecquerels (EBq) of radioactivity,[3] including 3.6 EBq of Caesium-137 and 0.74 EBq of Strontium-90.[1] For comparison, the Chernobyl disaster released from 5 to 12 EBq of radioactivity, but this radiation is not concentrated in one location.
The radiation level in the region near where radioactive effluent is discharged into the lake was 600 röntgens per hour in 1990, according to the Washington, D.C.-based Natural Resources Defense Council,[4][5] more than sufficient to give a lethal dose to a human within an hour.
Starting in the 1960s, the lake began to dry out; its area dropped from 0.5 km2 in 1951[1] to 0.15 km² by the end of 1993.[6] In 1968, following a drought in the region, the wind carried radioactive dust away from the dried area of the lake, irradiating half a million people with 185 petabecquerels (5 MCi) of radiation.[3]
Between 1978 and 1986 the lake was filled with almost 10,000 hollow concrete blocks to prevent sediments from shifting.[7]