Assessment of environmental risk and integrated index of the atmospheric surface layer pollution in the monitoring area of the Mayak Production Association

The purpose of the work is to estimate the level of contamination of the atmospheric surface layer by technogenic radionuclides in the monitoring area of the Production Association "Mayak" (“Mayak”). For these purposes the integrated pollution index and the summarized radiation risk index to the impact on biota based on radiation monitoring data were used. The environmental risk was estimated with the account of radiation exposure intensity, the monitoring area size and temporary pollution dynamics. The correlation of plutonium isotopes emissions and the radionuclide volumetric activity in the atmospheric surface layer was studied. Before burying radioactive waste and elimination of the lake area the “Karachai” emissions of plutonium isotopes were not the core factor determining the content of radionuclides in the atmospheric surface layer in the "Mayak" monitoring area. After the lake bury with the Karachaevsky rocky soil in 2015, the relationship between plutonium emissions and its volumetric activity in the atmospheric air over Ozersk and the village of Metlino has been monitored in the following years. From results of radioactivity monitoring in the “Mayak” monitoring area it follows that the integrated index of atmospheric pollution is much lower than 1, it indicates that the atmospheric pollution by plutonium radionuclides in the “Mayak” area is environmentally safe. The data, presented in ICRP publications and the Roshydromet recommendations are not exceeded. The main contributors to the integrated index of the atmospheric air pollution are plutonium isotopes. The estimate of the summarized risk index of atmospheric air pollution in the monitoring area, calculated in accordance with the recommendations of Roshydromet, is more than 10, but less than 20, it corresponds to the weak radiation impact on the "Mayak" Production Association. In this case, regular estimation of the impact of technogenic factors on radiation situation in the territory. Taking into account the potential radiation hazard of the enterprise, it is recommended to continue monitoring atmospheric air pollution with plutonium and other technogenic radionuclides.