Evaluation of sampling and analytical uncertainties and estimation of natural radioactivity levels in the soil samples in Kalpakkam, Tamilnadu

The high-purity germanium (HPGe) detector is used to quantify natural radioactivity concentrations in soil samples. The total uncertainty due to the contribution of the analytical method and sampling uncertainty is evaluated in this study. The relative sampling uncertainty values for 40K, 238U, and 232Th are found to be within 5%. The measured specific activity levels ranged between 225.6 ± 8.5 Bq/kg and 479.6 ± 13.0 Bq/kg for 40K, 12.1.6 ± 1.4 Bq/kg and 73.2 ± 2.7 Bq/kg for 238U, and 48.7 ± 2.6 Bq/kg and 548.7 ± 17.0 Bq/kg for 232Th, respectively. The radiological hazard parameters, such as absorbed dose rates and annual effective dose values, were estimated from the 40K, 238U, and 232Th activity concentration values. The absorbed dose rate values ranged between 45 nGy/h and 383 nGy/h with a mean value of 142 nGy/h. The annual effective dose values ranged from 0.06 mSv/y to 0.47 mSv/y with a mean value of 0.17 mSv/y.