Radioactive contamination around the former Soviet Union's Semipalatinsk nuclear test site and estimation of internal radiation dose for people

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Nuclear weapon tests by the former USSR at the Semipalatinsk Nuclear Test Site (SNTS) in Kazakhstan caused a vast amount of radioactive contamination around the test site. Dolon village is known as one of the most contaminated villages by radioactive fallout around SNTS. Calculated external gamma-ray dose in air by model ranged from 1 to 2 Gy, while TL measurement of a brick sample n Dolon taken from a church was close to about 0.5 Gy. Thus, In Dolon village, some discrepancies in the dose estimation for the village among investigators were pointed out. In relation to the effort to reconstract the radiation dose in Dolon village, the width and center-axis location of the radioactive plume were investigated based on the soil contamination data around Dolon and the nearby villages. Additional soil contamination data around Dolon were obtained during the period of this study. As a result, the plotted distribution formed a peak-like shape for Cs-137 and Pu-239,240. The center part of the plume passed over the residential area of Dolon with one sigma value of 1.5 km. Finally, 0.50 Gy 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.Parallel to the above works, to evaluate the present Pu and Cs-137 levels in the general population living near the SNTS and to estimate the associated alpha doses, Pu-239,240 and U isotopes in bone samples from more than 70 autopsies of residents were measured. By assuming that average concentration of Pu-239,240 in bone samples is the value at 45 years after instantaneous inhalation in 1955,the initial total and the effective dose for 45 years were estimated as 10 Bq and 1.2 mSv, respectively. The annual intake of total U and its effective dose for 60 years were estimated as 30 Bq for adult and 0.1 mSv, respectively, for chronic ingestion.