Assessment of the radiological impact of gamma and radon dose rates at former U mining sites in Kyrgyzstan

摘要

An assessment of the radiological situation due to exposure to gamma radiation, radon and thoron was carried out at the former uranium mining and processing sites in Shekaftar, Minkush and Kadji Sai in Kyrgyzstan. Gamma dose rate measurements were made using various field instruments and radon/ thoron measurements were carried out using discriminative radon (~(222)Rn)/thoron (~(220)Rn) solid state nuclear track detectors (SSNTD). The detectors were exposed for an extended period of time including at least three seasonal periods in a year, in different outdoor and indoor public and residential environments at the selected uranium legacy sites. The results showed that gamma, Rn and Tn doses were in general low, which consequently implies a low/relatively low radiological risk. The major radiation hazard is represented by abandoned radioactive filtration material that was being used as insulation by some Minkush residents for a longer period of time. Annual radiation doses of several hundred mSv could be received as a consequence of using this material in their houses. The radiation doses deriving from external radiation (gamma dose rate), indoor radon and thoron with their short-lived progenies in several cases exceeded national as well as international standards. Current doses of ionizing radiation do not represent any serious hazard to the health of the resident public, but this issue should be adequately addressed to further reduce needless exposure of resident public to ionizing radiation.