环境电离辐射体源表面剂量率的MC模拟计算及实验比较

Modeling dose-rate on/over the surface of cylindrical radio-models using Mont Carlo methods

目的 对核工业地质勘查计量站的 8个圆柱型环境电离辐射体源和两个本底模型上方不同高度处的空气吸收剂量率进行较为准确的定值。方法 采用蒙特卡罗软件MCNP ,对上述环境电离辐射体源和本底模型上方的空气吸收剂量率进行了模拟计算 ,采用 1台高气压电离室剂量率仪对各环境电离辐射体源和本底模型上方不同高度处的空气吸收剂量率进行了实测 ,模拟计算结果与实测结果以及其他工作者过去所作的剂量率测量和计算结果进行了比较。结果 MC模拟计算值与其他工作者得到的空气吸收剂量率理论值吻合较好 ,最大偏差小于 10 % ,一般偏差小于±5 %。结论 只要各种输入参数准确 ,采用MC模拟计算 ,可以得到辐射体源和本底模型上方不同高度处较准确 (3%不确定度 )的空气吸收剂量率模拟计算值。

Objective To determine the dose-rates on/over the surface of 10 cylindrical radio-models,which belong to the Metrology Station of Radio-Geological Survey of CNNC. Methods The dose-rates on/over the surface of 10 cylindrical radio-models were modeled using the famous Monte Carlo code-MCNP.The dose-rates on/over the surface of 10 cylindrical radio-models were measured by a high gas pressurized ionization chamber dose-rate meter,respectively.The values of dose-rate modeled using MCNP code were compared with those obtained by us in the present experimental measurement,and with those obtatined by other workers previously.Some factors causing the discrepancy between the data obtained by us using MCNP code and the data obtained using other methods are discussed in this paper. Results The data of dose-rates on/over the surface of 10 cylindrical radio-models,obtained using MCNP code,were in good agreement with those obtained by other workers using the theoretical method.They were within the discrepancy of ±5% in general, and the maximum discrepancy was less than 10%. Conclusions As if each factor needed for the Monte Carlo code is correct,the dose-rates on/over the surface of cylindrical radio-models modeled using the Monte Carlo code are correct with an uncertainty of 3%. ;