高浓缩钚材料贯穿辐射场计算方法研究

目的 为满足高浓缩钚材料操作人员辐射安全评价和核安全审评的要求，需要对高浓缩钚材料周围形成的贯穿辐射场进行计算分析，解决高浓缩钚材料发射的γ射线和中子射线贯穿机理和强度的计算问题。方法 本文在对高浓缩钚材料的组成及所含放射性核素的辐射特性进行深入分析的基础上，基于γ射线宽束减弱规律和中子分出截面理论，研究提出了适用于高浓缩钚材料γ剂量率和中子剂量率计算模式。结果 贴近高浓缩钚材料表面γ剂量率和中子通量理论计算值与实际测量值同一量级，表明计算模型是正确的。距离钚材料表面0、30、100 cm处γ剂量率实际测量值均大于计算值，并且距离越远相对误差越大；中子模拟计算值与实际测量值相对误差随距离的增加而减小。结论 通过原理分析和实测验证，证明本文提出的高浓缩钚材料辐射场计算方法是合理可行的，能够满足科学性和准确性要求。

Research on calculation method of the penetrating radiation field for the highly enriched Plutonium

Objective The calculation of the penetrating radiation field is required around highly enriched plutonium for the purpose of the workers' radiation safety assessment and the nuclear safety review, in which the penetration mechanism and the strength of the neutron and γ from plutonium needs to be analyzed deeply.Methods The composition and the radiation characteristic of the highly enriched plutonium is analyzed deeply, then the method which is appropriate for the γ and neutron dose rate calculation of the highly enriched plutonium is put forward based on the attenuation law of γ broad-beam and the neutron removal cross section theory.Results The theoretical calculation value of the surface γ dose rate and the neutron flux close to the highly enriched plutonium material is the same order of magnitude as the measured value, and shows that the model is correct. The actual measured values of γ dose rate from 0cm,30cm,100cm from the surface of plutonium material are all larger than the calculated values, and the farther the distance is, the larger the relative error is. The relative error between the neutron simulation and the actual measurement decreases with the increase of distance.Conclusion Through principle analysis and experimental verification, the calculation models presented for the penetrating radiation dose is reasonably and can meet the requirement of scientific and veracity.