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.

DOI: 10.1504/IJLR.2013.054172

International Journal of Low Radiation, 2013 Vol.9 No.1, pp.30 - 37

Received: 16 Feb 2012
Accepted: 13 Apr 2012
Published online: 13 Sep 2014 *

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