Exposure to high background radiation level in the tin mining area of Jos Plateau,Nigeria

Abstract

The present work deals with the radioactivity of samples of tin tailings collected from amining site in Jos, Nigeria. The activity concentrations of the samples were measured usinga gamma-ray spectrometer with a hyper-pure germanium detector. In situ dose rates atthe site were also measured using a precalibrated survey meter. Potassium-40was not detected in any of the studied samples. The activity concentrations of238U and232Th rangedfrom 17.1 × 102 to 16.6 × 103 Bq kg−1 andfrom 52.9 × 102 to47.5 × 103 Bq kg−1, with meanvalues of 72.2 × 102 and 16.8 × 103 Bq kg−1, respectively. The absorbed dose rates were between 4.0 and36.3 µGy h−1, with amean value of 13.5 µGy h−1, which is much higher than the world average of0.06 µGy h−1 for soil. The calculated effective dose rates varied between 2.8 and25.4 µSv h−1, with amean value of 9.4 µSv h−1, whereas the effective dose rates obtained for the in situ measurement varied between 6.0 and28.0 µSv h−1. The annual gonadal dose equivalent was calculated as 92.4 mSv. This is muchhigher than the world average dose equivalent rate to individuals from soil(0.30 mSv y−1).