网格划分对裂变矩阵加速的影响

Effect of mesh division on the fission matrix acceleration method

临界计算中,裂变矩阵加速方法能够有效地提高源收敛的速度。利用内、外迭代的观点对网格划分对裂变矩阵加速方法的影响进行了分析,并通过一个一维平板模型进行了模拟计算,指出随着网格的细分,加速效果越明显,但是考虑到方法的稳定性,一味地细分网格并不是很好的选择。为了解决这个问题,文章提出了基于网格变化的裂变矩阵加速方法,能够在不增加裂变矩阵阶数的同时起到和细分网格类似的效果,从而进一步提高裂变矩阵加速的效果,并使用数值实验进行了验证。

The fission matrix acceleration method can accelerate the convergence of source distribution in the Monte Carlo(MC)criticality calculation.The inner-outer iteration is introduced to analyze the effect of the mesh division on the fission matrix acceleration method.It's pointed out that the convergence rate increases with a refined mesh to tally the fission matrix but the refined mesh method has its limitation with the consideration of the stability of method.To solve this problem,the mesh changing method is proposed,which can improve the performance of the fission matrix acceleration method further without the increase of order of fission matrix.The improvement is verified by a 1 Dslab model.