Assessment of radon concentration and external gamma radiation level in the environs of Narwapahar uranium mine, India and its radiological significance

In the environs of uranium mining, milling and processing facilities and in the uranium mineralized terrain, a little higher ambient radon concentration and gamma radiation level may be expected in comparison with natural background. The present study gives a brief account of atmospheric radon concentration, gamma absorbed dose rate and radiation dose received by the members of public in the vicinity of Narwapahar uranium mine. The ambient radon concentration in the air in the study area was found to vary from 5 to 107 Bq m(-3) with geometric mean of 24 Bq m(-3) and geometric standard deviation of 1.74 Bq m(-3). The measured gamma absorbed dose rate in air at 1 m above the ground ranged from 87 to 220 nGy h(-1) with an overall arithmetic mean of 128 +/- A 18.5 nGy h(-1). The mean annual effective dose received by the members of public from inhalation of radon and its progeny and external gamma exposure was estimated to be 0.32 mSv year(-1), which is comparable to other reported values elsewhere.