External Radiation in Dolon Village Due to Local Fallout from the First USSR Atomic Bomb Test in 1949

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Dolon village, located about 60km from the border of the Semipalatinsk Nuclear Test Site, is known to be heavily contaminated by local fallout from the first USSR atomic bomb test in 1949. External radiation in Dolon was evaluated based on recent ^<137>Cs data in soil and calculation of temporal change in the fission product composition. After fitting a log-normal distribution to the soil data, a ^<137>Cs deposition of 32kBq m^<-2>, which corresponds to the 90th-percentile of the distribution, was tentatively chosen as a value to evaluate the radiation situation in 1949. Our calculation indicated that more than 95% of the cumulative dose for 50y had been delivered within 1y after the deposition. The resulting cumulative dose for 1y after the deposition, normalized to the initial contamination containing 1kBq m^<-2> of ^<137>Cs, was 15.6mGy, assuming a fallout arrival time of 3h and a medium level of fractionation. Finally, 0.50Gy of absorbed dose in air was derived as our tentative estimate for 1-year cumulative external dose in Dolon due to local fallout from the first USSR test in 1949.
日本放射線影響学会の論文