基于中子均方位移守恒的平均散射角余弦计算  

Calculation of average scattering cosine based on conservation of neutron mean square displacement

作　　者：秦帅 李云召[1] 贺清明[1] 曹良志[1] 吴宏春[1] QIN Shuai;LI Yunzhao;HE Qingming;CAO Liangzhi;WU Hongchun(School of Nuclear Science and Technology,Xi′an Jiaotong University,Xi′an 710049,China)

机构地区：[1]西安交通大学核科学与技术学院,陕西西安710049

出　　处：《哈尔滨工程大学学报》2023年第12期2208-2215,共8页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(U2067209);国家级青年人才项目(2019QNRC001);中核集团领创科研项目.

摘　　要：使用蒙特卡罗方法计算均匀化群常数时,一般以中子标通量为权重计算平均散射角余弦,会引入额外的计算误差。针对该问题,本文从中子均方位移和平均散射角余弦的关系出发,根据中子均方位移的统计结果,计算得到保证该物理量守恒的平均散射角余弦。基于蒙特卡罗粒子输运计算程序NECP-MCX,并使用各向异性较强的快中子反应堆问题对该方法进行了测试。相比于传统方法,反应堆有效增殖因子的偏差由588×10^(-5)~796×10^(-5)降低为-31×10^(-5)~266×10^(-5),相对裂变反应率分布的最大相对偏差由3.754%~4.675%降低为-0.990%~0.920%,均方根偏差由1.864%~2.444%降低为0.569%~0.612%。结果表明:本文方法可以可以有效降低传统方法的计算偏差,具有一定的应用价值。In the two-step calculation of reactor physics,the average scattering cosine is determined using the scalar flux as the weighting function in the Monte Carlo method for generating group constants,which introduces additional errors.Therefore,starting from the relationship between the mean square displacement and average scattering co-sine,this paper proposes a novel method that calculates the average scattering cosine,conserving the mean square displacement of neutrons.It is realized based on the Monte Carlo particle transport procedure NECP-MCX.Several fast reactor problems with strong anisotropy are selected to test the validity of the proposed method.Compared with the traditional method,the biases of multiplication factors decrease from 588×10^(-5)~796×10^(-5)to-31×10^(-5)~266×10^(-5).The maximum relative biases of relative fission reaction rates decrease from 3.754%~4.675%to-0.990%~0.920%,and the root mean squared biases decrease from 1.864%~2.444%to 0.569%~0.612%.The results show that the proposed method can effectively reduce the biases introduced by the traditional method,and has cer-tain application values.

关 键 词：均方位移 平均散射角余弦 群常数 蒙特卡罗方法 NECP-MCX 各向异性 反应堆物理 两步法计算 

分 类 号：TL329[核科学技术—核技术及应用]