Soroka Y. Scientific bases of ensuring environmental safety when handling materials containing natural radionuclides

The thesis presents the results of the research aimed to ensure environmental safety when working with materials containing natural radionuclides and technologies to reduce pollution by radionuclides, at the end, ensurance of the radioecological protection of the population and the environment in Ukraine. A critical analysis of the existing system and principles of population radiation safety and the environment while working with materials containing natural radionuclides in Ukraine. The methodology for assessing the safety for the population and the environment based on risk criteria for potential exposure in places of extraction and processing of materials containing natural radionuclides is proposed, which includes the developed methodology for calculating radiation doses for staff, workers and the public. It also allows to mitigate as much as possible negative influence of radioactive materials to population and environment. The question of its application for determination of the clearing level from radiation pollution of buildings and the territory of the former uranium object is considered. The influence of mining enterprises' activity on environmental pollution by natural radionuclides is investigated The processes of radon absorbtion on activated carbon have been studied and an accurate and easy-to-perform method of measuring radon flux density with the help of the proposed device for absorbent exposure (activated carbon) on the surface has been developed. The influence of radon exhalation on radioactive contamination of territories and premises is estimated and the standard of radon flux density from the surface of the territory for subsequent development is offered. The study of equivalent equilibrium volume activity levels of radon-222 in the premises of the old uranium mining city was carried out, and it was recommended to perform remedial anti-radon measures in the premises where the hygienic regulations are exceeded by 100 Bq·m-3, paying special attention to technical means which decrease radon admission into premises due to radon exhalation from surface. The dependences of radiation safety parameters in iron ore mines on mine air pollution by radon and natural radionuclides are determined and the classification of such mines according to the level of radiation safety is created, which is the basis for creating a radiation control system in these mines. The raw materials and technological wastes with the increased content of natural radionuclides are investigated and the levels of exemption from control of solid loose technological wastes with the increased content of natural radionuclides of series 238U, 235U та 232Тh are developed. Experimental studies have shown that uranium migration is observed along the profile of the reclamation layer due to its capillary uplift with humidity, and it is proved that high contamination of the layer with plumbum-210 and polonium-210, which are products of radon-222 decay, is mainly explained by gas transfer and its decay in the layer. Methodology and basic parameters of the system of enterprise radioecological monitoring for extraction and processing ores and materials enriched with natural radionuclides is substantiated, where the background values of mentioned parameters form the single tool for assessing the level of pollution from the enterprises. This is the only quality criteria applicable for such facilities. It is determined that industrial activity on the territory has led to the deterioration of the radiation background and requires rehabilitation measures. The Strategy of Rehabilitation of the Territory of the Former Uranium Production of the “Prydniprovsky Chemical Plant” has been proposed and the main strategic goals of rehabilitation and development of this industrial site have been formulated. Methodological and regulatory framework which increases the effectiveness of environmental safety in enterprises where there is a possibility of irradiating staff or the population with radioactive material of natural origin is scientifically substantiated and improved. Keywords: environmental safety, natural radionuclides, radon, radioecological monitoring, radiation doses