Comparative study of radon sources and associated health risk in four underground uranium mines.

This paper presents a comparative study of the quantitative estimation of Rn and its health risk from various sources in four underground uranium mines. Rn exhalation rates from uranium-bearing rocks and backfill materials were estimated by calculating the Rn concentration accumulated in an enclosed chamber into which radon was exhaled. This comparative study indicates a more significant effect of porosity on the exhalation rates. Dissolved Rn in mine water was estimated using scintillation cell and bubbler kit. The discrepancy in Rn concentration in the mines might be attributed to the variation in geological features, ore grade, and porosity. This study revealed that the maximum radon exposure was produced from the backfill mill tailings, followed by uranium ore and mine water in the mines. The radon dose values in the individual mines remained under the safe dose limit of 20 mSv year. The excess lifetime cancer risk (ELCR) and Rn-induced lung cancer cases (RnLCC) per million persons per year were also estimated.