Measurement of the radioactivity of238U,232Th,226Ra,137Cs and40K in soil using direct Ge(Li) γ-ray spectrometry

Radioactivity of the nuclides238U(235U),232Th,226Ra,137Cs and40K was measured in soil by direct γ-ray spectrometry using Ge(Li) detector. Relative laboratory method was used. Soil was dired, powdered, sieved and put into hemetically sealed container. CCRMP certified reference materials and compounds of the above nuclides mixed with fine quartz sand were used as references. Five and four γ-lines were used for the determination of232Th and226Ra, respectively, to obtain more accurate results. The most significant interferences, caused by the limited energy resolution of the detector, were resolved. In the case of ordinary soils, using one day duration of measurement and 1 kg mass of soil,232Th,226Ra and40K can be determined with less than 10% relative random error. Elevated concentrations of238U(235U) and226Ra were observed in soil samples collected around a coal-fired power plant in Ajka town, Hungary.