AUTHOR=Li Song , Zhang Qian , Liu Lei , Zhang Yongfa , Hao Jianli , Wang Xiaolong , Jiang Lizhi , Liu Xiaoya 

TITLE=Analysis of the fine-mesh subgroup method and its feasible improvement

JOURNAL=Frontiers in Energy Research

VOLUME=Volume 10 - 2022

YEAR=2023

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2022.1036063

DOI=10.3389/fenrg.2022.1036063

ISSN=2296-598X

ABSTRACT=The fine-mesh subgroup method (FSM) is proposed to treat the significant resonance self-shielding effect both effectively and accurately. Similar to the ultra-fine group method, FSM adopts a fine group structure on resonance energy range to avoid the extra resonance interference effect correction. To improve the efficiency, on the one hand, the one-group micro level optimization is adopted, so the subgroup fixed source equations will be only calculated on a certain number of pre-determined subgroup levels and an interpolation process is employed to obtain actual subgroup flux. On the other hand, the slowing down calculation is carried out for group condensation for multi-group transport calculation. The main theory and feasible improvements of FSM are analyzed in this paper. Several pin cell and lattice problems are applied to test the performance of FSM and the particle swarm optimization method is adopted to find the better group structure. The numerical results indicate a good performance both for accuracy and efficiency.