Whole-Core Transport Solutions with 2-D/1-D Fusion Kernel via p-CMFD Acceleration and p-CMFD Embedding of Nonoverlapping Local/Global Iterations

In this paper, we present two novel approaches to reactor core analysis: (1) whole-core fine-group deterministic transport calculations are accelerated by a partial-current-based coarse-mesh finite-difference (p-CMFD) method, and (2) a whole-core domain is decomposed into nonoverlapping local problems, with local problem transport solutions then embedded within the p-CMFD methodology in a two-level iterative scheme to provide a whole-core transport solution. To solve three-dimensional (3-D) reactor problems, both approaches use the two-dimensional/one-dimensional (2-D/1-D) fusion method as a solution kernel, which employs a 2-D method of characteristics in the radial direction and a 1-D S_N-like method in the axial direction. A refinement sensitivity study of a 3-D boiling water reactor assembly problem shows the stability and accuracy of the 2-D/1-D fusion method. We report the results of these two approaches as applied to three whole-core configurations of the C5G7 OECD/NEA 3-D benchmark problem and to a modified C5G7 benchmark problem with explicitly modeled cladding.