三区非均匀栅元X-Y几何块方法中子输运计算

基于中子积分输运理论，应用综合界面流和碰撞几率技巧的块方法，导出了处理三区非均匀栅元结构的二维（Ｘ－Ｙ）几何多群中子输运问题的数值模型。即对于由若干栅元组成的按Ｘ－Ｙ几何排列的堆芯结构，对每一类栅元剖分为圆柱形元件（如燃料棒、控制棒、可燃毒物棒等）、包壳和慢化剂三个均匀区，用碰撞几率（ＣＰ或ＰＩＪ）方法计算各区的中子通量分布；对于相邻栅元用ＤＰ１近似的中子流来耦合；因此，块方法具有精度高、速度快、能灵活处理各种几何问题的优点，是目前动力堆组件计算最有前途的方法之一。基于块方法基本理论，发展了三区栅元模型，导出了计算方法，编制了ＦＯＲＴＲＡＮ计算机程序。为验证其精度和适用性，对两个例题进行了计算，并与其它程序的计算结果进行了比较，证明功率分布和本征值均符合较好。

A BLOCK METHOD OF NEUTRON TRANSPORT CALCULATION ON X Y GEOMETRY WITH THREE SUBREGION

Based on neutron integral transport theory, a numerical model for multi-group neutron transport equation on X Y geometry with three subregions in each cell is developed with block method coupling interface current and collision probability techniques. In this model, for X Y geometrical reactor core composed of fuel lattices, collision probability method (CP or PIJ) is used to calculate neutron flux of cylindrical fuel rod, cladding, moderator in each lattice, while interface current technique is used to couple adjacent lattice with DP1 approximation. The model has advantage of high accuracy, short computer CPU and flexibility to treat different geometrical problems. It is one of the most suitable methods for power reactor assembly calculation. Based on basic theory of the method, numerical technique and theoretical model with 3 subregion cell are developed. To check its accuracy and practicality, two samples are calculated and compared with results by other programs, showing a good agreement in power distribution and effective multiplication factor.