¹³⁷Cs distribution on the territory of Romania 30 years after Chernobyl accident

To estimate the contribution of Chernobyl ¹³⁷Cs contamination, in 1993 and especially 2016, its total inventory was determined by gamma-ray high-resolution spectroscopy in 62 and respectively 747 soil samples covering the entire Romanian territory. This permitted to estimate the ¹³⁷Cs inventory as varying between 0.4 and 187 as well as between 0.2 and 94.2 kBq/m² for years 1993 and 2016, respectively. By representing the spatial distribution of ¹³⁷Cs inventory in Voronoi polygons, it was possible to evidence a decrease of the total ¹³⁷Cs inventory over entire Romanian territory with a factor of about 3 from about 3.6 TBq to less than 1.2 TBq, exceeding in this way the natural decay which suggests that a certain amount of ¹³⁷Cs was washed out by precipitation and, at a lower extent, was incorporated into plants. At the same time, by evaluating the maximum contribution of ¹³⁷Cs to the population exposure, in 1993 as well as in 2016, the supplementary annual effective dose did not exceed, in the majority of sampling points the value of 0.2 mSv/year.