Abstract The feasibility of the improved subgroup method coupled with the Sanchez-Pomraning Method (ISSP) is analyzed for the resonance self-shielding calculation of double heterogeneity (DH) problems in PWR. The Sanchez-Pomraning method is developed for both fixed source and the eigenvalue problems. The improved subgroup method adopts a fine-mesh energy structure to handle the resonance interference effect. In this process, the subgroup fixed source equations are solved to get the fine-mesh cross section and the slowing-down equations are solved for group condensation. To extend the improved subgroup method to DH condition, the Sanchez-Pomraning method is applied twice to the subgroup fixed source equation and slowing-down equation respectively. Afterward, the Sanchez-Pomraning method is used the third time for multi-group transport problems. The ultra-fine group method coupled with the Sanchez-Pomraning method (UFGSP) is also established for comparison with ISSP. Numerical validation shows that both ISSP and UFGSP could treat the DH resonance effect precisely.

中文翻译：

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基于Sanchez-Pomraning方法的改进亚组共振治疗对压水堆双异质性的评价

摘要 分析了改进子群法结合Sanchez-Pomraning法(ISSP)在压水堆双非均质性(DH)问题共振自屏蔽计算中的可行性。Sanchez-Pomraning 方法是为固定源和特征值问题开发的。改进的子群方法采用细网格能量结构来处理共振干涉效应。在这个过程中，求解子群固定源方程得到细网格截面，求解减速方程进行群凝聚。为了将改进的子群方法扩展到DH条件，对子群固定源方程和减速方程分别应用两次Sanchez-Pomraning方法。之后，第三次使用 Sanchez-Pomraning 方法解决多组传输问题。还建立了超细群法与 Sanchez-Pomraning 法 (UFGSP) 相结合以与 ISSP 进行比较。数值验证表明ISSP和UFGSP都可以精确地处理DH共振效应。