Research into the current radiological state of air and monitoring observations on STS and the adjacent territory.

The article presents the assessment of levels and the pattern of STS air radioactive contamination. Levels of air radioactive contamination with artificial radionuclides at different distances from ground zeros of nuclear tests (0.08-10 km) were determined. The maximum concentration of 239+240Pu in the air did not exceed 6.5·10-3 Bq/m3 at the crater ridge of the "Atomic Lake", the one at the P3 technical site, the "Experimental Field", reached 1.6·10-2 Bq/m3. Based upon monitoring observation data (2016-2021) on the STS territory, 239+240Pu concentration in the air of the "Balapan" and "Degelen" sites varied between 3.0·10-9 and 1.1·10-6 Bq/m3. In settlements adjacent to the STS territory, 239+240Pu concentrations in the air is: Kurchatov t. - 3.0·10-9 to 6.0·10-7 Bq/m3, the Dolon small village - 4.5·10-9 to 5.8·10-6 Bq/m3, the Sarzhal small village - 4.4·10-7 to 1.3·10-6 Bq/m3. Values derived for concentrations of artificial radionuclides at STS observation posts and the adjacent territory are at the level of background values for this region.

Transfer parameters of radionuclides from soil to plants at the area of craters produced by underground nuclear explosions at the Semipalatinsk test site.

A study to determine 137Cs, 90Sr, 241Am, 239+240Pu radionuclides in vegetation cover of the area of craters produced by underground nuclear explosions at the Semipalatinsk test site (STS) is summarised in this paper. Transfer factors (Tf) required for the quantitative description of the radionuclides transition from the soil to aboveground plant parts were found to be highest for sagebrush (Artemisia sublessingiana), Tf values for 90Sr were gradually decreasing with increasing distance from the dump zone. When arranging the radionuclide transferring factors in descending order, the following sequence was obtained: 90Sr Tf > 137Cs Tf > 241Am Tf > 239+240Pu Tf, which is consistent with International data. All Tf derived are much higher than those ones derived earlier for epicenters of aboveground nuclear tests and are closest to values for conventionally "background" areas at the Semipalatinsk test site.