SOME ASPECTS OF PLUTONIUM IN AND AROUND THE FORMER SOVIET UNION'S SEMIPALATINSK NUCLEAR TEST SITE

Abstract

Field studies were conducted in the Semipalatinsk region to contribute to the investigations of the present radioecological situation resulting from the radioactive fallout from nuclear test explosions carried out at the former Soviet Union's Semipalatinsk nuclear test site (SNTS). For this purpose, surface and core soil samples were collected at more than 60 sites, including several settlements such as Dolon, Chagan and Sarzhal, located within and outside the SNTS area. The radioactivity of the long-lived radionuclides 137Cs, 238Pu and 239,240Pu and the atomic ratio 240Pu/239Pu were determined by a combination of gamma-spectrometry and radiochemical separation followed by alpha-spectrometry and/or ICP-MS. The results showed distinct variations in 137Cs and 239,240Pu inventories in soils from different sampling sites. Although 137Cs activity was within typical environmental levels, except for the area near the first nuclear test site and Balapan, 239,240Pu was at elevated levels in all the areas visited. This high contamination of soil by Pu was caused by weapons-grade Pu from the SNTS, as identified by the 240Pu/239Pu atomic ratio.