Definition of the Naturalized Flow of the Dnipro Using the Restoration Method

Abstract

The article summarizes the results of long-term radioecological monitoring of the environment radioactive state within the former 'Prydniprovsk chemical plant' and adjacent territories at the preparatory stage life cycle of uranium legacy site. Data analysis have been determined the background activity levels of natural radionuclides (in particular 238U, 226Ra, 230Th, 210Pb, 210Po) in soils, underground and surface waters, air (fall density and volume activity), exhalation of 222Rn from the soil surface and its volume activity. The results of the determined dynamics and trends in the formation of pollution of environmental elements, which form the main factors of exposure of workers and the population, are presented. Areas with elevated dose rate (≥0.5 μSv·h-1) occupy more than 30% of the entire legacy site territory. In the soil activity may be 10 to 1000 times higher than background (30-50 Bq·kg-1) and can exceed 1000 times the exemption level. In aerosols 238U and 226Ra activitis exceeding the background (0.1 µBq·m-2·s-1, 11.5 µBq·m3) by 100-200 times only during periods of earthworks, under normal conditions they are up to 1.5-2.0 times. The monthly average activity 222Rn in the air of open space are 4-5 times higher of the background (median 200±68 Bq∙m-3), in some areas they can exceed by up to 50 times. In the buildings premises on the site 222Rn can exceed the reference level (250 Bq∙m-3) by 1-5 times, and in individual basements by up to 100 times. The data analysis proves that main ways of exposure of workers are external gamma radiation, the inhalation exposure routes from aerosol pollution and the spread of OA 222Rn in the air can be significant only for workers work at the legacy site and do not pose a threat to the city's population. Radiation assessment contamination of underground and surface water showed in present conditions aquatic pathways cannot form any significant contributions to the radiation exposure dose of the public. The obtained results and data analysis of monitoring observations were used to substantiate the measures of the remediation strategy legacy site.