Resonance Treatment for Double Heterogeneity Based on Subgroup Method

The improved subgroup method coupled with Sanchez-Pomraning method (ISSP) was proposed for the resonance self-shielding calculation of double heterogeneity (DH) problems. ISSP employed a fine-mesh energy structure to avoid the extra resonance interference treatment. The DH subgroup fixed source equations and the neutron slowing-down equations were established to obtain the effective resonance cross-section in particle and matrix. Finally, the transport calculation under DH condition was carried out. By contrast with the continuous-energy Monte Carlo method and the ultra-fine group method, numerical verification results indicate that ISSP could provide resonance cross-section in DH condition accurately and effectively.