Title: Evaluation of natural radioactivity in rocks of Nilgiri hills and their radiation hazard to mankind
Authors: N. Krishnamoorthy; S. Mullainathan; S. Murugesan
Addresses: Research and Development Centre, Bharathiar University, Coimbatore, Tamil Nadu 609 305, India; Department of Physics, CSI College of Engineering, Ketti, The Nilgiris, Tamil Nadu 643 215, India ' Department of Physics, AVC College of Engineering, Mannampandal, Mayiladuthurai, Tamil Nadu 609 305, India ' Department of Physics, Sathyabama University, Chennai, Tamil Nadu 600 119, India
Abstract: Twenty three rock samples were collected from various altitudes of Nilgiri hills, Tamil Nadu, India. A survey was carried out to determine the activity concentration of selected radionuclides (238U, 232Th, 40K) by means of gamma-ray spectroscopy using NaI (Tl) detector. From the measured spectra, the mean activity of 238U, 232Th, 40K are 7.13 Bq kg−1, 30.47 Bq kg−1 and 346.06 Bq kg−1, respectively. To evaluate the radiological effects, the absorbed dose rate, effective absorbed dose rate, radium equivalent activity, external and internal hazard indices, and radioactivity level index are also calculated. The mean absorbed dose rate of gamma radiation ranged from 11.90 nGy h−1 to 108.22 nGy h−1. The activity concentration of 238U, 232Th, 40K and the various radiological effects are below the internationally recommended maximum values.
Keywords: natural radionuclides; activity concentration; hazard indices; Nilgiri rocks; India; natural radiation; health hazards; gamma radiation; low radiation.
International Journal of Low Radiation, 2013 Vol.9 No.1, pp.30 - 37
Received: 16 Feb 2012
Accepted: 13 Apr 2012
Published online: 28 May 2013 *