Natural radioactivity in soil samples of Yelagiri Hills, Tamil Nadu, India and the associated radiation hazards

The natural radioactivity of soils at Yelagiri hills has been studied in this paper. The radioactivities of 25 samples have been measured with a NaI(Tl) detector. The radioactivity concentrations of U-238, Th-232 and K-40 ranged from <= 2.17 to 53.23, 13.54 to 89.89 and from 625.09 to 2207.3 Bq kg(-1), respectively. The measured activity concentrations for these radionuclides were compared with world average activity of soil. The average activity concentration of Th-232 in the present study is 1.19 times higher than world median value while the activity of U-238 and K-40 is found to be lower. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity Ra-eq, the absorbed dose rate D-R, the annual effective dose rate and the external hazard index (H-ex) have been calculated and compared with the internationally approved values. The study provides background radioactivity concentrations in Yelagiri hills. (C) 2012 Elsevier I.td. All rights reserved.