Convergence Improvement of Coarse Mesh Rebalance Method for Neutron Transport Calculations

Abstract

The coarse mesh rebalance (CMR) is a simple acceleration method that is commonly used for transport calculations though it is conditionally stable, i.e. acceleration failed under certain calculation conditions. In this paper, a new acceleration scheme, i.e. the generalized coarse mesh rebalance (GCMR) method, is proposed and applied to improve convergence property of the CMR method. Definitions of partial neutron currents used in CMR are modified in the present method and convergence property of CMR is improved by the modifications. The proposed method was applied to transport calculations in slab and light water reactor assembly geometries. The calculation results were compared with those by the CMR and the coarse mesh finite-difference (CMFD) acceleration methods, and it was revealed that the present method significantly improves the convergence property of the traditional CMR method. Since the present method can be easily applied to existing transport codes using the CMR method, it is considered as a practical acceleration method.