Effects of sieved particle size and equilibration time on the measurement of radionuclides in soil by gamma-ray spectrometer / 中国辐射卫生

ABSTRACT

Objective The effect of sieved particle size and equilibration time of soil samples on the measurement of radionuclides was studied to improve the accuracy of the specific activity of radionuclides in soil samples measured by gamma spectrometer. Methods The collected soil samples were dried and divided into four parts. After sieved with width of the mesh 2.0 mm, 1.0 mm, 0.5 mm and 0.25 mm respectively, they were filled into sample containers and sealed. The activity concentrations of 226Ra, 210Pb, 228Ra, 40K and 137Cs in different sieved soil samples were then measured at the sealed interval of 0, 4, 8, 12, 16, 21, 25 and 29 days by HPGe gamma-ray spectrometry respectively. Results The coefficients of variation ofthe specific activities of 226Ra, 210Pb, and 228Ra in soil samples measured at different equilibration intervals range from 0.9% to 4.3%. The coefficients of variation of the specific activities of 226Ra, 210Pb, 228Ra, 40K and 137Cs in soil samples with different sieved particle sizes range from 3.7% to 14.1%. Conclusion When the specific activities of radionuclides are determined by gamma-ray spectrometer, the effect of the sieved particle size on the measurement result must be considered, and its impact is higher than the equilibration time. This study is very useful for improving the accuracy of the determination of radionuclides in soil sample using gamma-ray spectrometer.