Measurements of natural radioactivity in rock samples collected from Lalitpur, India using gamma-ray spectrometry

The concentrations of the natural radionuclides namely ²²⁶Ra, ²³²Th and ⁴⁰K in rock samples collected from Lalitpur city of Uttar Pradesh (India) have been determined using a Gamma-ray spectrometry. The concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied rock samples range from BDL to 65.25, BDL to 4.06 and BDL to 550.2, respectively. The concentrations of these radionuclides are compared with the world recommended values. Surface radon exhalation rates (E_A) and mass exhalation rates (E_M) in these samples were measured by 'Sealed Can Technique' using LR-115 type II track detectors. Surface radon exhalation rate is found to vary from 73.59 to 329.06 with an average value 184.49, while mass exhalation rates ranges from 2.83 to 12.67 with an average value of 7.11. Also, we have evaluated the radiological hazard of the natural radioactivity, the radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, and their representative level index as well as the values of both external and internal hazard indices. These studies have been compared with the internationally permitted values. (author)