通量展开节块法求解六角形几何三维多群中子扩散方程

提出了一种在三维六角形几何节块内数值求解多群中子扩散方程的节块法，该方法把节块内各群中子通量分布用解析基函数近似展开．为了改善节块耦合关系，采用了一种新的节块边界条件：面平均偏流0次矩和1次矩同时保持连续．将响应矩阵技术应用于迭代求解过程，使得该方法具有较高的计算效率．通过对基准问题的校验计算表明，该方法能准确地给出有效增值系数以及节块功率；对于二维多群问题，所有基准题的组件最大功率偏差均小于1％．

Flux Expansion Nodal Method for Solving Multigroup Neutron Diffusion Equations in Hexagonal-z Geometry

A new flux expansion nodal method was developed to solve three-dimensional multigroup neutron diffusion equations in hexagonal-z geometry. The method expands the intranodal homogeneous flux distributions in analytic basis functions for each energy group. In order to improve the nodal coupling relations, a new type of nodal boundary condition was proposed, which simultaneously requires the continuity of both the zero- and first-order moments of partial current across the nodal surfaces. The response matrix technique was used for the iterative solution of the nodal diffusion equations, which greatly improves the computational efficiency of this method. The numerical results of several benchmark problems show that the multiplication factor and nodal powers can be predicted accurately. Moreover, the maximum error of the nodal powers is less than 1% for all the two-dimensional benchmarks.