连续变化介质蒙特卡罗模拟方法研究  

Research on Monte Carlo Methods for Particle Transport in Media with Continuously Varying Cross-Sections

作　　者：李泽光[1] 张熙司[1] 王侃[1] 

机构地区：[1]清华大学工程物理系核能科学与工程管理研究所,北京100084

出　　处：《核动力工程》2010年第S2期53-57,87,共6页Nuclear Power Engineering

基　　金：国家自然科学基金项目(10775081);"973"课题资助项目(2007CB209800)

摘　　要：在连续变化介质中,总的核截面沿粒子的飞行路线不断发生变化,传统的用于总截面为常数的介质的蒙特卡罗模拟方法不再适用。为了解决这类问题,本文采用了3种蒙特卡罗模拟方法,即逐步逼近法、Delta-tracking法和光程法,对该类问题进行分析研究。对计算结果进行比较并考虑三维计算中的实际情况,选取了Delta-tracking方法作为模拟连续变化介质的主要方法,并在合理简化的一维模型下,对多种不同截面变化情况进行了计算,对蒙特卡罗方法模拟连续变化介质的问题进行了详细的分析。针对Delta-tracking方法在模拟变化剧烈的连续介质时抽样效率低的问题,提出了改进的Delta-tracking方法,通过设置截断比,可以有效提高在介质核截面剧烈变化时的模拟效率。In the traditional Monte Carlo method,the cross-sections are assumed to be constant,but this Monte Carlo technique is no longer applicable in continuous materials where the material cross-sections vary over the particle flight paths.Three Monte Carlo methods are developed to solve this kind of problem in this paper,namely Sub-stepping method,Delta-tracking method and Direct Numerical method.Based on the results from different methods to calculate the particle transport in media with continuously varying cross-sections,the comparison of three methods is made and Delta-tracking method is used as the main method to solve this kind of problem.And also an improved Delta-tracking method is posted in this paper to make this method more powerful in solving problems where the material cross-sections vary sharply over the particle flight paths.

关 键 词：蒙特卡罗模拟 连续变化介质 Delta-tracking方法 

分 类 号：TL329.2[核科学技术—核技术及应用]