Radioecological monitoring in the vicinity of Rostov NPP. The analysis of results of long-term investigations

Abstract

The purpose of this work was to assess the influence of the Rostov NPP (consisting of 4 units with VVER1000 reactors) on the radioecological situation in the region of the station location within 18 years from the start of the first power reactor. Based on the results of observations at the radioecological monitoring network established in 2001, which included seven control sites and five control points, the content of natural and artificial radionuclides in environmental objects, agricultural products and foodstuffs was analyzed. It was shown that over the entire period under consideration, the average content of 90Sr in the soils of agroecosystems of the 15-km zone of influence of the Rostov NPP varied within 1.7-7.4 Bq/kg, and 137Cs – 7.5-14.9 Bq/kg. It was not detected any trends to increase in the concentrations of artificial radionuclides in the soil throughout the considered territory. The variation range of the average content of natural radionuclides in soils was 561-634 Bq/kg for 40K, 23.4-27.5 Bq/kg for 226Ra and 32.7-35.9 Bq/kg for 232Th. The average concentration of 90Sr in the grain was in the range of 0.1-0.68 Bq/kg, and 137Cs – 0.23-0.54 Bq/kg. Even the maximum specific activity values of artificial radionuclides in food grain were below the SanPiN standards 55 times for 90Sr and 65 times for 137Cs. The maximum levels of 137Cs in vegetables and potatoes and vine crops were 80 times lower than the SanPiN standards. The maximum levels of specific activity of 90Sr in milk were more than 400 times lower than the SanPiN standard (25 Bq/kg), and for 137Cs (standard 100 Bq/kg) this difference was 600 times. Vegetable crops were characterized by minimal transfer factors (TFs) of radionuclides. TFs of 90Sr in vegetables, depending on the product type, was in the range of 0.04-0.17, and for 137Cs it was in the range of 0.008-0.2 (Bq/kg)/(kBq/m2 ). Maximum TFs of radionuclides were noted in grasses. TF of 90Sr in natural and perennial grass was 0.75-2.2, and for 137Cs it was 0.28-0.86 (Bq/kg)/(kBq/m2 ). The differences in transition factors between vegetables and grass reached 50 times, and on average, they were 10-20 times. It was noted that all types of crops accumulated 90Sr on average 2-5 times more in comparison to 137Cs ac cumulation. It was shown that the content of artificial radionuclides in the water of the Tsymlyansk reservoir is 163 and 183 times lower than the permissible level for 90Sr and 137Cs, respectively. The analysis of 18-year results of observations of the radioecological situation in the vicinity of the Rostov NPP allows to conclude that the operation of this NPP in normal mode and the commissioning of new power-generating units did not lead to a recorded increase in the content of artificial radionuclides in agricultural products, foodstuffs and environmental objects.