Measurement of natural radioactivity using NaI (Tl) detector in soil samples collected from Aizawl, Mizoram, India

Abstract

Measurement of natural radioactivity in soil samples collected from Aizawl district, Mizoram, was carried out using gamma spectrometer 5"X 4" NaI (Tl) detector. Soil samples were collected from 15 different sites located in various parts of Aizawl district. The activity concentrations were measured for three specific radionuclides, viz. 238 U, 232 Th and 40 K. The activity concentration of 238 U nuclides was found to be in the range of 20.13 Bq/kg to 60.4 Bq/kg, with an average value of 34.03 Bq/kg. For 232 Th nuclides, the activity concentration ranges between 53.68 Bq/kg to 161.03 Bq/kg, with an average value of 90.71 Bq/kg. For 40 K nuclides, it ranges from 279.58 Bq/kg to 964.62 Bq/kg, with an average value of 765.35 Bq/kg. To assess the uniformity of natural radioactivity in soil with respect to exposure, the radium equivalent activity was calculated and was found to be in the range of 135.62 Bq/kg to 350 Bq/kg, with an average value of 217.32 Bq/kg. Except for 238 U nuclides, the overall average activity concentrations of 232 Th and 40 K nuclides in collected soil samples were found to be higher than world average, but lower than the critical value set by IAEA. The radium equivalent activity value in all the samples was found to be lower than the critical value of 370 Bq/kg. Hence, no radiological hazards were observed within the specified study area.