Assessment of exposure of miners to the α-rays of long-lived radionuclides associated with respirable ore dust in the Jaduguda U mine

The present work is intended to quantify the locational and operational internal exposures of workers due to the α-rays of long-lived radionuclides associated with the airborne respirable particulate in the underground U mine at Jaduguda. The concentrations of the dust and the α-rays of the long-lived radionuclides in the mine air are log-normally distributed with respective geometric means (χg) of 0.49 mg m−3 and 21.25 mBq m−3 and geometric standard deviations (σg) of 1.7 and 1.88, respectively. There exists a moderately positive linear correlation (correlation coefficient=0.43) between the dust and the activity concentrations. The α-activity of the long-lived radionuclides in respirable dust, measured radiometrically, assumes a χg of 41.73 Bq g−1 with a σg of 1.98 which is in close correspondence with the analytically evaluated value for the U mill tailings sand of identical particle size range. The internal radiation exposure was estimated to be only about 5% of the annual effective dose limit.