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本文介绍用DIF3D (NOD)求解二、三维六角形几何系统下中子扩散方程的理论模型及数值计算方法。六角形节块内的中子通量密度分布采用高次多项式近似表示,最后导出通量矩方程及偏流的响应矩阵方程。应用粗网再平衡和渐近源外推方法加速收敛。参考此方法编制了计算程序NDHEX,并对一些六角形基准问题进行了计算。结果表明:NDHEX的计算结果与DIF3D(NOD)的计算结果符合很好;与差分程序相比,具有更高的精度与计算效率。它可用于快堆计算。
In this paper, we introduce the theoretical model and numerical method for solving neutron diffusion equations under 2D and 3D hexagonal geometry with DIF3D (NOD). The distribution of neutron flux density in the hexagonal nodules is approximated by the high-order polynomial. Finally, the flux equation and the response matrix equation of bias current are derived. Application of coarse network rebalancing and asymptotic source extrapolation to accelerate convergence. Reference to this method has compiled the calculation program NDHEX, and calculated some hexagonal reference problems. The results show that the calculated results of NDHEX are in good agreement with those of DIF3D (NOD). Compared with the differential program, the results of NDHEX have higher accuracy and computational efficiency. It can be used for fast reactor calculations.