土壤中光子致地表光子辐射剂量率转换系数的EGS模拟

Calculation of Dose Rate Conversion Coefficients for External Exposure to Photon emitters in Soil Based on EGS Monte Carlo Code

基于镜像、积分原理,采用EGS蒙特卡罗程序对土壤中光子致地表光子辐射剂量率的转换系数进行了模拟计算,给出了能量50 keV^3 MeV光子的转换系数。与其他研究者的计算结果相比,除0.2、0.4 MeV两个能量点的值相对偏差较大(25%)外,其余均小于15%。依据该转换系数计算了土壤中单位比活度的天然放射性核素所致的地表光子辐射剂量率,与其他研究者计算结果的相对偏差小于10%。

The conversion coefficients of photon dose rate above ground from photon emitters in soil were calculated using the EGS Monte Carlo code. Calculations were performed for 16 photon energies from 50 keV to 3 MeV and for 30 plane radius from 5 cm to 200 m. The conversion of photon dose rate above ground from specific activity of nuclides form238 U decay chain,232 Th decay chain and40 K in soil were also given. The comparison between these results and the data deduced previously by other authors indicates a good agreement,less than 10% difference.