基于MC的辐射场快速计算程序设计与验证

Program Design and Verification of Rapid Calculation of Radiation Field Based on MC

摘要: 针对当前核电厂辐射场剂量计算需求，基于蒙特卡罗方法，跟踪模拟粒子输运与碰撞过程，对辐射场快速计算方法进行研究，采用分裂、轮盘赌、偏倚抽样等三类减方差技巧加速收敛；同时采用MPI进行并行加速，设计并验证辐射场计算程序NPTS；选取15个MCNP5自带的临界基准题，较为全面地考察该程序在临界计算方面的正确性，选取4个固定源计算例题，验证固定源问题处理的正确性，同时对并行效率进行验证分析。结果表明：选取的临界基准题Keff相对偏差小于5‰，4个固定源基准题模型的中子伽马能谱与MCNP5程序基本一致，验证了粒子输运的精准性；而且计算效率优于MCNP5程序，计算选取模型百核并行效率高于95%，缩短了程序计算时间，为建立核与辐射防护剂量快速计算体系提供参考和依据。

Abstract: For the current demand of radiation field dose calculation of nuclear power plant, based on the Monte Carlo method, the rapid calculation method of radiation field is studied by tracking and simulating the particle transport and collision process, and three kinds of subtraction variance reduction such as splitting, roulette and bias sampling are adopted. At the same time, MPI was used for parallel acceleration, and the radiation field calculation program NPTS was designed and verified. 15 MCNP5 critical reference questions were selected to examine the correctness of the program in the critical calculation more comprehensively, 4 fixed source calculation questions were selected to verify the correctness of the fixed source problem, and verify the parallel efficiency. The results showed that the relative deviation of Keff was less than 5‰, and the neutron gamma spectrum of 4 fixed source models was basically the same as that of MCNP5, which verified the accuracy of particle transport. The computational efficiency is better than that of the MCNP5 program, and the parallel efficiency of hundreds cores for model calculation is higher than 95%, which significantly shortens calculating time of the program and provides a reference and basis for the establishment of a re-al-time three-dimensional radiation field calculation system.