Isotopic Pu, U, and Np signatures in soils from Semipalatinsk-21, Kazakh Republic and the Southern Urals, Russia

Mass spectrometry measurements of Pu, U and Np isolated from soils contaminated by the 1957 accident at the Mayak nuclear complex in the Southern Ural mountains (‘Kyshtym accident’) and from soils collected at and near the Former Soviet Union (FSU) test site at Semipalatinsk-21 are reported. The results provide a coherent isotopic data set suggesting (1) that Pu recovered from irradiated uranium fuels processed at Mayak formed the source material for Pu devices tested at Semipalatinsk-21; (2) that 237Np in the breached Mayak storage tank resulted, principally, from enrichment of this radionuclide in waste streams during the processing of low burn-up uranium fuels to recover both Pu and U and (3) the presence of 236U at both sites may be useful in tracing inputs of this, and other transuranic radionuclides, to nearby river systems that flow to the Arctic Ocean.