Searching for Strontium, Americium and Plutonium Isotopes in Contaminated Soils

In the course of decommissioning former nuclear facilities the surrounding premises have to be surveyed due to possible contaminations of radioactive material. Radioactive contamination of the premises is usually caused by common nuclides which often occur in substantial activity concentrations in nuclear facilities. A lot of fission- or activation products (137Cs, 134Cs, 133Ba, 60Co, 152Eu ...) can be detected quite easily in soils by gamma-spectrometry. Problematic radionuclides in this context are nuclides like 3H, 14C and 90Sr, which are pure beta emitters. Also the transuranic nuclides 238Pu, 239Pu, 240Pu and 241Pu are of particular importance in this work These radionuclides don´t have suitable gamma lines for detection, but they can be detected by LSC (3H, 14C, 90Sr, 241Pu) and alpha spectrometry (238Pu, 239Pu, 240Pu). This paper demonstrates the sample preparation procedure prior to the determination of 3H, 14C, 90Sr, 238Pu, 239Pu, 240Pu and 241Pu by alpha spectrometry and LSC by appropriate chemical separation. The analyses showed that the ratios of activity concentrations of Pu-isotopes are constant. Thus, by defining a suitable key nuclide it was possible to determine a nuclide vector for Pu-isotopes in soils for the premises of a former research reactor.