结合源偏倚和权窗的蒙特卡罗全局减方差方法  

Monte Carlo global variance reduction method combining source bias and weight window

作　　者：张显 刘仕倡 魏军侠[1] 李树[1] 王鑫 上官丹骅[1] Zhang Xian;Liu Shi-Chang;Wei Jun-Xia;Li Shu;Wang Xin;Shangguan Dan-Hua(Institute of Applied Physics and Computational Mathematics,Beijing 100094,China;School of Nuclear Science and Engineering,North China Electric Power University,Beijing 102206,China;Software Center for High Performance Numerical Simulation,China Academy of Engineering Physics,Beijing 100088,China)

机构地区：[1]北京应用物理与计算数学研究所,北京100094 [2]华北电力大学核科学与工程学院,北京102206 [3]中国工程物理研究院高性能数值模拟软件中心,北京100088

出　　处：《物理学报》2024年第4期113-118,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12175067,12035002,12375164);河北省自然科学基金(批准号:A2022502008);中央高校基本科研业务费专项资金(批准号:2022JG002);中国工程物理研究院创新发展基金(批准号:CX20210045,CX20200028)资助的课题.

摘　　要：全局计数问题在反应堆pin-by-pin模型蒙特卡罗模拟和多物理耦合计算中动态粒子输运蒙特卡罗模拟等重大研究领域中都有广泛的应用场景.大量的全局减方差算法研究立足于全局计数误差分布的展平,由此提高全局计数的整体效率.本工作针对两种高效全局减方差算法,即均匀计数密度算法(属于源偏倚算法的一种)和权窗算法的结合展开研究,提出利用均匀计数密度算法的偏倚因子调整权窗下限,由此实现两种算法的有机结合.基于Hoogenboom-Martin压水堆全堆基准题中开展了一系列对比测试,验证了混合全局减方差算法更优于单一权窗算法或均匀计数密度算法,尤其是在降低最大误差方面.同时,基于新的指标,验证了均匀计数密度算法较经典的均匀裂变源算法具有更好的表现.研究结果表明,本文提出的混合全局减方差算法能高效求解全局计数问题,进一步促进了相关领域的研究.The global tally problem has a wide range of applications in major research fields such as Monte Carlo simulations of pin-by-pin reactor models and time-dependent particle transport problems in multi-physics coupling calculations.Due to the uneven power distribution of the simulated system,the statistical errors of all tallies are unevenly distributed,resulting in some low global efficiency.For this kind of problem with global characteristics,it is necessary to develop global variance reduction techniques to obtain the accurate distribution of target tallies in the entire space.A large number of global variance reduction algorithms have been studied based on the consideration of flattening global tally error distribution,so as to improve global efficiency.This work focuses on the combination of two efficient global variance reduction algorithms,namely,the uniform tally density algorithm and the weight window algorithm,which belong to source bias and transport process bias,respectively.In tally,a method is proposed to adjust the weight window parameters by using the bias factor of the uniform tally density algorithm.Then,the weight window method will be used to reduce the weight fluctuation caused by the uniform tally density method.In this way,an organic combination of these two algorithms can be realized.A series of comparative tests are carried out based on the Hoogenboom-Martin pressurized water reactor benchmark,and it is verified that the hybrid global variance reduction algorithm proposed in this work is better than the single weight window algorithm or the uniform tally density algorithm.In terms of reducing the maximum error,the global efficiency of the hybrid algorithm is 2.6 times and 3 times that of the weight window algorithm and the uniform tally density algorithm,respectively.In addition,through the comparative analysis of computational asymmetry degree and computational efficiency,it is verified that the uniform tally density algorithm has better performance than the classical uniform fission site

关 键 词：蒙特卡罗方法 全局减方差 均匀计数密度算法 权窗算法 

分 类 号：O241[理学—计算数学]