Pragya Pandit, Dibakar Ghosh

The following work is a part of wider uranium prospecting programme of the Atomic Mineral Directorate for Exploration and Research (AMD) for mapping radioactive anomalies in mineralized regions of Siwalik, Himachal Pradesh. This study reports the analysis of average activity concentration, potential radiological hazards; radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin) and excess cancer life time risk (ECLR) calculated due to naturally occurring radioactive materials (NORM); Radium (226Ra), Thorium (232Th) and Potassium (40K) in uranium mineralized zone of Siwaliks for health risk assessment. The geometric mean value of calculated indoor and outdoor annual effective dose in the Una, Hamirpur and Kangra region are 0.88 and 0.22; 1.77 and 0.44; 1.86 and 0.46 mSvy-1 respectively. The average air absorbed dose rate were measured to be 118 nGyh-1 in Una, 163 nGyh-1 in Hamirpur and 135 nGyh-1 in Kangra district respectively. Correlation study indicated good correlation of the measured gamma dose rate and the estimated gamma dose rate with a correlation coefficient of (R2 =0.62). This data provides important information on the radiation risk and spatial variability of the natural terrestrial gamma radiation in the Siwalik region.