Solodovnikova L. Decreasing the Unsafe Level of Radon Stored at Radioactive Waste Repositories in Ukraine

The Thesis for the PhD degree (candidate of engineering sciences in the specialty of 21.06. 01 – Environmental Safety. – Scientific Research Institution "Ukrainian Scientific Research Institute of Ecological Problems". Kharkiv, 2020. This thesis is devoted to the issues of the reduction of the unsafe level of radon at radioactive waste repositories in Ukraine. This research paper delves into the reasons for the creation of the radioactive waste repositories in Ukraine. It describes the open-type tail repository Sukhachevske, the second section of the former production agglomeration “The Pre-Dniper Chemical Plant” , closed –type repository of the solid-state radioactive waste of the former section of nuclear weapon at the “Makariv” facility, closed –type repository of the solid –state radioactive waste at the Kharkiv State Interbranch Specialized Industrial Complex, the Corporation (SISIC) UkrSO “Radon” . Consideration is given to the reasons of the formation of the increased concentrations of radon-222 inside them and the character of its propagation in the ambient air of the radioactive waste repositories in question was analyzed. This research paper substantiates the need for the creation of the standard source of radon as a constituent part of the National Primary Standard of the Unit of the Volumetric Activity of Radon -222 required to calibrate the measuring instrumentation that is recommended for the use to provide a reliable measurement of the indices of volumetric activity and the radon flow density in studied radioactive waste repositories. It is necessary for the taking of antiradon measures at test facilities. This research paper gives the data relating to the indices of volumetric activity in the ambient air of the repositories that keep the solid-state radioactive waste at the Kharkiv State Interbranch Specialized Industrial Complex, the Corporation (SISIC) UkrSO “Radon”, the solid-state radioactive waste repository of the former section of nuclear weapon at the “Makariv” facility and the flow density of radon emanated by the surface of the second section of the tail repository Sukhachevske, the production agglomeration “The Pre-Dniper Chemical Plant” . The data analysis showed the need for a decrease in the unsafe radon level at radioactive waste repositories. To decrease the unsafe level of radon at the test repositories of radioactive waste this research paper recommends to use the forced ventilation for the solid-state radioactive waste repository Kharkiv State Interbranch Specialized Industrial Complex, the Corporation (SISIC) UkrSO “Radon”; the solid-state radioactive waste repository of the former section of nuclear weapon at the “Makariv” facility should be liquidated according to the SOW-1 agreement and antiradon coatings should be used for the most unsafe sections of the tail repository, the second section of the former production agglomeration “The Pre-Dniper Chemical Plant”. Key words: environmental safety, radioactive waste repositories, radon unsafety. The radon -222 standard source, the volumetric activity of radon 222, the radon flow density and technical arrangements.