Terrestrial Gamma Radiation in Kochi Prefecture, Japan

概要

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Absorbed dose rates in air(dose rate)from terrestrial gamma radiations obtained using a scintillation survey meter ranged from 13.8 to l87 nGy/h depending on the geological features in Kochi Prefecture. Mean dose rates of four geological belts were found in the following order ; Alluvial Deposits < Sambagawa Belt = Chichibu Belt < Shimanto Belt. The mean dose rate of the prefecture was about 60 nGy/h, which was 20% higher than that of Japan as a whole. The mean effective dose rate per person in this prefecture was about 0.37 mSv/y, which was the same as the Japanese mean. The ratio of the mean dose rates of ^<40>K, nuclides of the thorium series and the uranium series in the soil determined using a germanium detector were 2 : 2 : 1. The relationship between ^<40>K, ^<208>Tl and ^<214>Bi was positive, and therefore ^<40>K, nuclides of the thorium series and the uranium series were considered to have the same behavior in the soil. ^<137>Cs in the soil ranged from 1.4 to l50 Bq/kg with a mean of 24.5 ± 23.1(S.D.)Bq/kg, suggesting that we continue to be under the influence of nuclear tests in the atmosphere.
公益社団法人日本薬学会の論文
2001-08-01