Radiation Situation at the Tailing Dump of the Stepnogorsk Mining-Chemical Combine and Adjacent Territories. Message I

Abstract

Purpose: Assessment of the radiation situation at the tailing dump of the Stepnogorsk Mining-Chemical Combine (SMCC) and the settlements around. Material and methods: The tailing dumps of the SMCC and the settlements near located of Aksu, Kvartsytka and Zavodskaya were objects of the radioecological research. Field expedition studies were performed during the summer period and consisted in carrying out a detailed gamma survey of the territory of the investigated objects and settlements, sampling of surface waters, vegetation, surface and layered soil samples. In settlements, along with sampling and studying the gamma background, the equivalent equilibrium volume activity of radon daughters in residential and industrial premises was determined. To determine the concentrations of the studied radionuclides a background was selected, within which the levels of their global deposition were studied. To calculate the individual effective radiation dose of the population the National Radiation Protection Board methodology was used as the basis. Results: In the northern part of the tailing dump of the SMCC in the adjoining territory, a radioactive contamination site was found where the specific activity values for 226Ra, 232Th and 210Pb reach values of 1500–2000 Bq/kg. On the territory of the Aksu settlement, 5 local areas with the area from 25 to 1000 m2 were found, with the intensity of ambient dose equivalent of gamma radiation from 0.39 to 0.86 µSv/h. In the Zavodskaya village, two areas with increased levels of gamma radiation intensity were identified. Conclusion: The obtained results of field work and laboratory analytical studies testify to the negative impact of the tailing dump of the SMCC on the environment of adjacent territories, expressed in contamination of soil, water and vegetation with radionuclides. The nature of the abnormal areas on the territory of the settlements of Aksu and Zavodskaya excludes their origin from the tailing dump of the SMCC. The appearance of these areas of contamination may be due to the use of materials of the 3rd class in sanitary and hygienic standards for improvement and road construction. The probable annual effective dose for the population living in the radioactive local areas of the Aksu ~6.5 mSv/year, at the normal rate of 1 mSv/year from man-made radiation sources.