Residual radioactivity in the soil of the Semipalatinsk Nuclear Test Site in the former USSR.

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.