The acceleration of improved Tone's method in advanced reactor lattice neutron spectrum calculation

Abstract

This paper focuses on the acceleration of solving fixed-source equations in improved Tone's method. Since each equation is independent of the other with respect to the energy variable, the parallel calculation based on energy group domain decomposition was used in the advanced reactor lattice neutron spectrum calculation code TULIP. In order to balance the load of each CPU, the equally-divided strategy and a weighting-based strategy, which were used for the division of energy groups, were proposed and discussed. In the weighting-based strategy, the cross sections were used to calculate the weighting so that the iteration behavior could be caught. Therefore, the CPU load was balanced, and the parallel efficiency was improved. Moreover, the selection of the initial value was also evaluated. To verify the improvement, several tests based on fast and thermal neutron spectrum were calculated. According to the analysis of calculation time and parallel efficiency, using the initial value that was calculated with the homogeneous problem could save more than half of the calculation time. Meanwhile, the weighting-based strategy for parallel calculation could balance the CPU load so that the parallel efficiency was improved about 10%–80%, which is based on different tests.