Abstract

Tanzania is currently considering to start mining uranium in various parts of the country. Manyoni and Bahi areas were identified as among the potential sites for uranium mining and processing in the country. The study investigated the natural background of gamma ray dose rates in the vicinity of the proposed Manyoni and Bahi uranium deposits in Tanzania. Ambient gamma doses were measured using a RAM DA3-2000, model BAK-1670. The mean and standard deviation background radiation dose to the population at Manyoni and Bahi deposits were 0.26 ± 0.14 mSv/y and 0.18 ± 0.06 mSv/y respectively. A good linear relationship between means of annual effective dose and altitude was observed for each site with R² values of 87 % and 76 % for Manyoni and Bahi deposits respectively. The comparison of the mean effective dose rate between the Manyoni and Bahi deposits has shown significant difference (P = 0.0276). It is concluded that the mean natural background gamma ray dose at proposed mines is less than the global average value of 0.5 mSv/y and the annual effective dose limit of 1.0 mSv/y recommended by ICRP. The future increase of the radiation after commencement of mining activities is expected which calls for selection and implementation of stringent control measures.

Key Words: Uranium, Pollution, Gamma Radiation, Dose, Radionuclide

DOI: https://ejesm.org/doi/v10i8.10