85Kr as an Environmental Contaminant

概要

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Problems of environmental contamination by 85Kr are investigated. 85Kr is produced by fission of nuclear fuels and most of it is discharged to the atmosphere during the reprocessing of spent fuels. Because it is a rare gas, it is difficult to retain it by the conventional method. Once discharged, it remains for a long time in the atmosphere and results in global contamination as well as local contamination.The discharge rate at currently-operating reprocessing plants is about 4×103 Ci·d-1 per t·d-1 and the annual average concentration of 85Kr at a few kilometers is about 5×103pCi·m-3 and the corresponding average gonad dose and skin dose are 85μrad·y-1 and 10.5 mrem·y-1 respectively.The concentration of 85Kr in the atmosphere is about 15pCi·m-3 in 1970, but for the year 2000 the predicted value is 2500pCi·m-3 and the corresponding annual skin dose is 5200μrad.The status of the work on 85Kr removal and the uses of recovered one are also reviewed.
日本保健物理学会の論文