Determination of U and Th in soil and plants obtained from a high natural radiation area in China using ICP-MS and gamma-counting

This study was carried out for the determination of U-238 and Th-232 concen trations in soil and various foods obtained in high natural radiation areas in China for estimating the internal radiation doses caused by these radio nuclides. Knowledge of the daily dietary intakes of the nuclides through fo ods is essential to evaluate the internal radiation dose. Several analytica l methods were evaluated for their applicability and quality assurance. The accuracy and precision of ICP-MS is considerably better for determining tr ace elements like U and Th in fine powder samples. The estimated annual eff ective dose is 0.302 mu Sv/y for U-238 and 1.86 mu Sv/y for Th-232 in the h igh natural radiation area, and 0.0101 mu Sv/y for U-238 and 0.177 mu Sv/y for Th-232 in the control area.