Improved subgroup method coupled with particle swarm optimization algorithm for intra-pellet non-uniform temperature distribution problem

Abstract

Due to the Doppler broadening effect, the conventional subgroup weights of different temperatures correspond to different energy ranges. Therefore, the conventional subgroup fixed source equation could not be established without approximation between different temperatures. In this study, the improved subgroup method coupled with the particle swarm optimization algorithm (ISPSO) is proposed. The subgroup fixed source equation is solved for different temperatures by sharing the same set of subgroup weights, which are calculated by generationally updating the particle position during the particle swarm optimization. Afterward, the partial subgroup levels are obtained by the least square method. Besides, ISPSO adopts the fine mesh structure for the resonance interference treatment, then the multigroup effective resonance cross section is obtained by the group condensation. The subgroup parameters of ISPSO could be either generated online or pre-determined. The numerical verification indicates that ISPSO could accurately handle the resonance treatment for the complicated temperature conditions.