Background radiation study in Coimbatore city, Tamilnadu

摘要

The activity concentration and absorbed gamma dose rates due to primordial radionuclides (238U, 232Th and 40K) have been determined for the soil of Coimbatore city using NaI(Tl) gamma-ray spectrometer. The average activity concentrations of 232Th, 238U and 40K in the soil samples have been found to be 31.4 Bq·kg?1, 12.8 Bq·kg?1 and 698.0 Bq·kg?1, respectively, which give the total gamma dose rate contribution of 56.4 nGy·h?1. Grab sampling technique has been used to determine the indoor radon (222Rn) and thoron (220Rn) progeny levels in different dwellings in the city. The concentrations of radon and thoron progenies range from 0.4 to 10.4 and from 0.7 to 12.7 mWL with a mean value of 1.4 mWL and 3.1 mWL, respectively. The annual effective dose due to radon and thoron progeny has been found to be 0.14 mSv·y?1.