Study of primordial radionuclides and radon/thoron exhalation rates in Bageshwar region of Kumaun Himalaya, India

The measurements of primordial radionuclides (Ra-226, Th-232 and K-40) and radon exhalation rates in soil samples were performed in Bageshwar region of Kumaun Himalaya, India using gamma-ray spectrometry and scintillation detector based radon monitor, respectively. The average concentrations of Ra-226, Th-232 and K-40 in the investigated region were found to be 36 Bq kg(-1), 50 Bq kg(-1) and 1595 Bq kg(-1), respectively. The average values of radon and thoron mass exhalation rates were observed to be 29 mBq(-1) kg(-1) s(-1) and 256 mBq(-1) kg(-1) s(-1), respectively. The average value of thoron surface exhalation rates was observed to be 2281 mBq(-1) m(-2) s(-1). The external exposure to Ra-226, Th-232 and K-40 is estimated in terms of different hazard assessment indices and dose quantities. The high values of Th-232 content in soil samples indicate the presence of thorium mineralization in the vicinity of study area. The methodology adopted and results obtained are discussed in details.