P1各向异性散射特征线方法研究及应用

基于各向同性散射的中子输运方程特征线方法,计算实际组件能谱时经输运修正后,散射矩阵中P0自散射截面可能出现一定量的负值,影响数值稳定性。本文开发了P1各向异性散射特征线方法,并研制了计算程序PEACH-A。压水堆栅元基准问题的验证结果表明,PEACH-A程序具有较高的计算精度。对典型富集度的UO_2、MOX燃料栅元及其组合问题进行了敏感性分析,结果表明,针对MOX燃料及富集度差异较大的UO_2燃料栅元组合问题有必要采用P1各向异性散射。

Research and Application of Method of Characteristics with P1 Anisotropic Scattering

The method of characteristics (MOC) based on the neutron transport equation with isotropic scattering may encounter problems of negative P0 self-scattering cross-section when performing lattice spectrum calculation after transport correction,which influences the numerical stability.The MOC with P1 anisotropic scattering was proposed in this paper,based on which an MOC code named PEACH-A was developed.The results of PWR cell benchmark problem indicate that PEACH-A code has a high numerical accuracy.The sensitivity analyses were performed for single UO2 cells,single MOX cells,and combined cells with typical fuel enrichments.The results indicate that it is necessary to employ the P1 scattering for MOX fuels and the UO2 fuel lattice which consists of fuel pins with large enrichment differences.