Radiochemical evaluation of groundwater around Mika uranium mineralization and environs

Abstract

Seventeen groundwater samples around Mika uranium mineralization were collected, and the ²²²Rn concentrations were measured using a DURRIDGE RAD7 electronic radon detector. The ²²²Rn concentrations in the groundwater ranged from 2350 to 46200 Bq m^–3 with an average of 29 400 Bq m^–3. The results show that 76.5% of the groundwater samples collected have ²²²Rn concentrations far above the US EPA maximum contaminant level (MCL) of 11.1 Bq L^–1 (for states without radon monitoring policy and enhanced indoor air programs), and only 23.5% have lower values. On the other hand, all the ²²²Rn levels were below the MCL of 100 Bq L^–1, recommended by EU as the level that warrants consideration of possible remedial actions. Borehole samples show relatively higher ²²²Rn concentrations than samples collected from open wells. The annual effective dose due to ingestion (H_ing) of ²²²Rn in the groundwater ranged from 0.05 to 0.92 mSv, with an average of 0.59 mSv. These values are within the ICRP recommended reference level of 1 mSv year^–1 for the intake of the radionuclide in water by the general public for a prolonged exposure.