Evaluation of Existing Exposure around the Sborishte Former Uranium Mining Site (Case Study) – B. Kunovska, K. Ivanova, M. Yovcheva, A. Angelova

Uranium mining industry in Bulgaria started operation in 1945, followed by in situ leaching technology in the beginning of 1970-ties. Two decades later (1990) all uranium mining sites in the country are closed. However the radioactive discharges from these sites continue cause various environmental problems and after the closing phase.

Sborishte (Southern Bulgaria, Sliven region) is a one of uranium mining site, where two methods: underground mines and in situ leaching (ISL) were applied. The aim of the study is to assess the radiological impact on living environment, related to former uranium mining activities in the vicinity of Sborishte village. The assessment is performed on the base of systematic control on radiological parameters. Systematic control on radiological parameters involves: measuring gamma dose rate and analyzing uranium contamination in surface water and specific activity of natural radionuclides in soil and sediment samples. For evaluation of radiological contamination in environment, the concentration of uranium in water and sediment were tracked in time. The range of gamma dose rate around the site is typical for the natural background. A high value up to 2.56 microSv/h was measured on waste piles. The range of uranium concentration in water flowing from the mining sites is from 0.287 to 1.0 mgU.l-1. The range of uranium concentration in sediment was from 1.2 to 19 mgU.kg-1.

The sediment was sampled from the same sites where the water were. In order to evaluate the existing exposure of people, conservative dose assessments were done using IAEA recommended models.

Keywords: uranium mining; radiological impact; environmental, natural uranium.