Objective To design and build a set of experimental equipment for neutron radiation irradiation by using the 241Am-Be neutron source.
Methods In the preliminary work, the spatial distribution data of the neutron energy spectrum and the gamma energy spectrum inside and outside the device were simulated by Monte Carlo method, and the changes of radiation fluence rate with spatial distribution was studied. The model of the 241Am-Be neutron device was established, and the neutron transport process in the irradiation field was studied using the method of shadow cone, inverse square law and other data analysis methods.
Results Based on the simulation results, the normalized effective does of fast neutron fluence at the measurement point is about 72.9 pSv/n, and the one of photon fluence is about 3.04 pSv/γ. The ratio of effective dose of photon fluence to neuteon is about 4.17%.
Conclusion Using Monte Carlo method, a standard model of 241Am-Be neutron source was constructed, the shadow cone design was optimized, and the feasibility of using the shadow cone conversion method to establish a standard neutron source radiation device was discussed.
摘要： 目的 拟利用 241Am-Be 中子源设计并建立一套中子辐射照射实验装置。 方法 采用蒙特卡洛 (Monte Carlo) 方 法, 模拟计算装置内外中子能谱和 γ 能谱空间分布数据, 研宄中子注量等随空间分布的变化规律;初步建立镅铍中子 装置的数学模型, 采用影锥法、平方反比律验证等数据分析方法, 对中子输运过程进行研宄。 结果 模拟获得测量点 处归一化快中子注量有效剂量约为 72.9 pSv/n, 光子约为 3.04 pSv/γ, 光子注量有效剂量与中子注量有效剂量的比值约 为 4.17%。 结论 利用蒙特卡洛方法, 构建了镅铍中子源标准装置模型, 优化了影锥设计, 初步讨论了将影锥转换法用 于建立中子源辐射照射装置的可行性。