Application of the SPH method to account for the angular dependence of multigroup resonant cross sections in thermal reactor calculations

The issue of the angular dependence of the multigroup total cross sections in the multigroup transport equation solution was recognized a long time ago. Only recently has its impact on resonant self-shielding been identified. A viable solution for this problem is the superhomogenization (SPH) corrections. In the present work, two applications of the SPH method are presented, one applying to the APOLLO3® deterministic calculations with the multigroup cross sections condensed from the TRIPOLI-4® Monte Carlo simulation results and the other applying to a subgroup method based on the fine-structure equation. The numerical results show the effectiveness of the SPH method in dealing with this difficulty in both situations. This work also demonstrates that the subgroup method based on the fine-structure equation plus the SPH corrections is a practical, effective and accurate resonant self-shielding solution for the PWR fuel pin-cell and fuel assembly calculations.