Assessment of Radionuclide Concentration and Radiation Dose in Rock in Singrauli Coalfield, India

This study was conducted at the Singrauli coal mine environment in Singrauli coalfield, India. The activity concentrations of thorium (${}^{232}\mathrm{Th}$), uranium (${}^{238}\mathrm{U}$), and potassium (${}^{40}\mathrm{K}$) in rock samples were analyzed by gamma spectrometry using a $p$-type high-purity germanium (HPGe) detector with a carbon fiber window. From terrestrial radionuclide activity concentration, the ambient radiation gamma dose rate was calculated using UNSCEAR 2000 coefficients. The average activity concentrations ${}^{232}\mathrm{Th}$, ${}^{238}\mathrm{U}$, and ${}^{40}\mathrm{K}$ were $77.6\pm 38.2$, $122.6\pm 46.1$, and $843.5\pm 26.0\mathrm{Bq}·{\mathrm{kg}}^{-1}$, respectively. The average activity ratio of ${}^{232}\mathrm{Th}/{}^{238}\mathrm{U}$ in various types of rocks was $1.8\pm 0.5\mathrm{Bq}·{\mathrm{kg}}^{-1}$. The radium equivalent activity (Raeq) for various types of rock samples varied from $\mathrm{132.8.1}\pm 2.8$ to $382.9\pm 6.2\mathrm{Bq}·{\mathrm{kg}}^{-1}$, with an average value of $317.7\pm 6.53\mathrm{Bq}·{\mathrm{kg}}^{-1}$. The absorbed average gamma dose rate was $145\pm 44\mathrm{nGy}·{\mathrm{h}}^{-1}$. The annual average effective equivalent dose was $0.29\pm 0.09\mathrm{mSv}·{\mathrm{y}}^{-1}$.