Natural radioactivity associated with bituminous coal mining in Nigeria

Gamma spectroscopic method was used to determine the natural radioactivity associated with the mining of Nigerian bituminous coal for the purpose of determining the radiological implications of coal mining in the country. The activity concentrations of the radionuclides detected range from 0.20±0.002 to 48.42±5.32 Bq kg−1. The overall natural radionuclide contribution to the radioactivity of the environment was found to be 404.16±23.44 Bq kg−1. Of this, coal waste (tailing) alone contributed 49.5% representing the largest contribution. Coal contributed just 5.5%. A comparison of the concentrations obtained in this work for coal with those from other parts of the world indicates that the radioactivity content of the Nigerian bituminous coal is not significantly different. The outdoor and indoor exposure rates in air 1 m above the ground are estimated to be (6.31±1.20)×10−8 and (7.57±1.20) ×10−8 Gy h−1, respectively, for the mining environment. These values compare very well with the global values reported by UNSCEAR: 5×10−8 and 6×10−8 Gy h−1, respectively. The resulting annual effective dose equivalent estimated is (4.49±0.74)×10−4 Sv yr−1. This also compares favourably with the global value −4×10−4 Sv yr−1, reported by UNSCEAR.