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This paper reports preliminary results on plutonium isotopie composition in soil sampled at the Semipalatinsk Nuclear Test Site in the former USSR. The soil was sampled in October 1994 from two locations in the test site, the first nuclear explosion site and the bank of the crater called "Bolapan" along the Shagan River Site. The Pu isotopie composition of these samples was determined through the measurements of ""Pu/^Pu (and 242 Pu/ 239 Pu) atom ratios by high resolution ICP-MS, 24 'Pu by a low background liquid scintillation counting method and 238 Pu and 239,240 Pu by alpha-ray spectrometry. As a result, a high level of 239 · 240 Pu with weapon-grade Pu was detected in the first nuclear explosion site and Bolapan. The isotopie composition of the Pu in the soil for the 1st nuclear explosion site was estimated to be 238 Pu 0.006%, 239 Pu 96.5%, 240 Pu, 3.48%, 24, Pu 0.01% and 242 Pu 0.004%, and for the Bolapan to be 238 Pu 0.19%, ™Pu 93.4%, 240 Pu 6.30%, 241 Pu 0.08% and 242 Pu 0.03%.

This paper deals with our efforts to survey residual radioactivity in the soil sampled at the Semipalatinsk Nuclear Test Site and at off-site areas in Kazakhstan. The soil was sampled at the hypocenter where the first Soviet nuclear explosion was carried out on 29 August 1949, and at the bank of the crater called "Bolapan," which was formed by an underground nuclear detonation on 15 January 1965 along the Shagan River. As a comparison, other soil was also sampled in the cities of Kurchatov and Almaty. These data have allowed a preliminary evaluation of the contemporary radioactive contamination of the land in and around the test site. At the first nuclear explosion site and at Bolapan, higher than background levels of 239,240Pu with weapons-grade plutonium were detected together with fission and activation products such as 137Cs, 60Co, 152Eu, and 154Eu.

This paper is a report on our survey of residual radioactivity in the soil of the Semipalatinsk nuclear test site in the former USSR. The soil was sampled at approximately 30 sites along the roads connecting Kurchatov City, ground zero for the first USSR nuclear test, Balapan, Degelen Mountain and Salzhal settlement. The radioactivity levels of 137 Cs, 238 Pu and 239 -240 Pu as well as the ^Pu/^'Pu atomic ratios in the soil were determined. Although ,37 Cs was within typical environmental levels except for an area near ground zero, 239 ' 240 Pu was at elevated levels contaminated with weapons-grade plutonium in all areas we visited.

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