基于变分节块法六角形Quasi-diffusion程序开发及验证  

Development and Verification of Hexagonal Quasi-diffusion Code Based on Variational Nodal Method

作　　者：庄坤 王连杰[2] 刘琨[2] 颜江涛 尚文 ZHUANG Kun;WANG Lianjie;LIU Kun;YAN Jiangtao;SHANG Wen(College of Materials Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 211106,China;Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610041,China)

机构地区：[1]南京航空航天大学材料科学与技术学院,江苏南京211106 [2]中国核动力研究设计院核反应堆系统设计技术重点实验室,四川成都610041

出　　处：《原子能科学技术》2023年第1期147-155,共9页Atomic Energy Science and Technology

基　　金：江苏省自然科学基金青年基金(BK20210304);核反应堆系统设计技术重点实验室基金(NBC20008);中国博士后科学基金(2020M68594);江苏省博士后基金(YBA20016)。

摘　　要：传统扩散理论在中子各向异性强的堆芯计算中具有较低的精度,Quasi-diffusion方程相比于传统扩散方程引入更少的近似,通过艾丁顿因子描述传统扩散理论不能反映的中子流各向异性特点。国内外对六角形几何三维Quasi-diffusion方程研究有所不足。针对艾丁顿因子计算的非线性特点,本文基于“两步法”的思想,将艾丁顿因子看作是一个特殊的少群参数,采用中子能谱适应性更好的蒙特卡罗程序SERPENT计算,并对传统扩散变分节块法进行拓展,开发了六角形组件堆芯计算程序VNMQD。采用3D VVER1000基准题、RBWR单组件问题、3D BN600简化模型对程序进行了验证,结果表明:VNMQD程序开发正确,对于非均匀性较强的堆芯,VNMQD比传统扩散方法计算精度更高、计算效率接近,实现了计算精度和计算效率的平衡。New type reactors usually adopt advanced fuel types and more anisotropic fuel arrangements,the neutron spectrum is very different from that of pressurized water reactor,and the neutron anisotropy is stronger.If using the neutron transport theory,although better results can be obtained,the computational efficiency is low.If the traditional diffusion theory is used,the calculation efficiency can be improved,however,the complex neutron energy spectrum and strong neutron anisotropy in the core decrease the calculation accuracy.In this study,the core calculation and analysis method based on quasi-diffusion equation was employed.One of the basic assumptions established by traditional diffusion theory is that the angular flux of neutrons is a first-order function of angle,but the quasi-diffusion equation does not adopt this assumption,and an Eddington factor is used to express product of the angular flux of neutrons and angle vectors.The Eddington factor can describe the anisotropic characteristics that cannot be reflected by traditional diffusion theory,and the form of quasi-diffusion equation is similar to the traditional diffusion equation.Most of the current researches applied the quasi-diffusion equation to accelerate the calculation neutron transport.Due to the computational complexity of the Eddington factor,the studies on the quasi-diffusion equation independently employed to the reactor calculation,especially for the reactor with hexagonal assembly are insufficient.Aiming at the characteristics of nonlinear calculation of the Eddington factor,this study regarded the Eddington factor as a special few-group constant based on“two-step”method,and adopted Monte Carlo code SERPENT of better neutron energy spectrum adaptability to calculate.For three-dimensional multi-group quasi-diffusion equation,based on Galerkin variation principle and Lagrange multiplier method,this study established a functional including the nodal balance relationship and boundary condition in the entire region,and used the Ritz discrete me

关 键 词：变分节块法 六角形 Quasi-diffusion方程 艾丁顿因子 

分 类 号：TL32[核科学技术—核技术及应用]