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

To estimate the contribution of Chernobyl 137 Cs 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 137 Cs inventory as varying between 0.4 and 187 as well as between 0.2 and 94.2 kBq/m 2 for years 1993 and 2016, respectively. By representing the spatial distribution of 137 Cs inventory in Voronoi polygons, it was possible to evidence a decrease of the total 137 Cs 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 137 Cs was washed out by precipitation and, at a lower extent, was incorporated into plants. At the same time, by evaluating the maximum contribution of 137 Cs 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.