Whole-core transport computation via overlapping local/global iteration

Abstract

In the current practice of reactor design analysis, whole-core diffusion nodal method is used in which nodal parameters are provided by single-assembly lattice physics calculation with net current zero boundary condition. Thus, the inter-assembly transport effect is not incorporated. In this thesis, the overlapping local/global (OLG) iteration framework is described that removes the limitation of the current method. It consists of two-level iterative computations: half-node overlapping local problems embedded in a global problem. The local problem can employ fine-group transport methods, while the global problem is an equivalent coarse-group transport model based on partial current-based coarse-mesh finite difference (p-CMFD) methodology. The method is tested on several highly heterogeneous multi-slab problems and 2-D heterogeneous problem with encouraging results.