Analysis of naturally ocurring radioactive material levels associated with a uranium mining in Malawi

This research was carried out to assess levels of Natural Radioactivity in water, soil, and mine waste at Kayelekera uranium mine in Malawi. Gamma ray spectrometry equipped with High Purity Germanium detector was used for quantification of the radionuclides. The activity concentration of radionuclides ²³⁸U, ²³²Th and ⁴⁰K were determined in water, soil, and waste samples from the mining site and surrounding communities.. The mean radioactivity concentrationsin water for ²³⁸U, ²³²Th and ⁴⁰K were 0.53 ±0.16 Bqkg-1, 0.97 ± 0.13 Bqkg-1and 10.8± 0.95 Bqkg-1 respectively. The mean radioactivity concentrations in soil for ²³⁸U, ²³²Th and ⁴⁰K were 27.23 ± 0.73 Bqkg^-1, 90.37 ± 1.13 Bqkg^-1and 1197 ± 4.03 Bqkg^-1 respectively. For waste samples, the mean activity concentrations for ²³⁸U, ²³²Th and ⁴⁰K are 320±36.67kBq/kg, 235.67x10³±36.67kBq/kg and 557.33±21.67kBq/kg respectively. In soil samples, the mean activity concentration for Uranium was lower and for Thorium and potassium were higher than the worldwide activity values.The mean committed effective dose for water samples was calculated to be 0.23 mSv while for soil, mean annual effective dose was estimated at 0.14 mSv which are both below the ICRP recommended level of 1 mSv for public exposure. The mean value of the radium equivalent activity for soil samples was 248.61±57 Bqkg^-1 which is lower than the recommended limit of 370 Bqkg^-1.The mean value of the radium equivalent activity for waste was estimated at 700±160.17 kBqkg^-1. From this research, it can be concluded that the water and soil from the study area can be used without posing any radiological hazard to the public due to U/Th-decay series and its short-lived progenies, while waste material from the mine may pose radiological hazard to workers in the absence of appropriate radiation protection strategy. (author)