Activity concentrations of 60 Co, 137Cs and 241Am in sieved soil and soil inclusions from the «Taiga» peaceful nuclear explosions site

The article presents results of comparative study of 137 Cs, 60 Co, and 241 Am activity concentrations in components of the soil samples collected in 2009 on the territory adjacent to the «Taiga» peaceful nuclear explosions site (the Perm region, Russia). The objective of the study was to identify differences between: 1) non fractionated native soil, 2) the soil passed through a sieve with a mesh size of 1.2 mm, and 3) the screened out coarse components. Measurements of the radionuclides activities in counting samples were performed using a semiconductor gamma spectrometer. Statistically significantly lower activity concentrations of 137 Cs (factor of 1.2), 60 Co (factor of 2.2) and 241 Am (factor of 2.6) were found in the finely dispersed sieved fraction of soil compared to the native soil. On the opposite, in the solid radioactive inclusions selected from the screened out coarse fraction, the activity concentrations of 137 Cs, 60 Co and 241 Am were significantly higher compared to those in the native soil. Especially large differences (up to a factor of 10 and more) between the native soil and radioactive inclusions were observed for the refractory and low-volatile 60 Co and 241 Am. Presumably, these radionuclides were concentrated predominantly in the glassy substance of the radioactive inclusions. For 137 Cs, the unevenness in the contamination of different soil components was less pronounced. The results obtained will be used to standardize methods for assessing radioactive contamination of the territory at the sites of peaceful nuclear explosions