A Study of Superhomogenization Applied to PHWR Lattices

Abstract

Superhomogenization (SPH) is an advanced lattice homogenization method which has been developed initially for light-water-reactor (LWR) lattices whereby fuel elements are arranged in a rectangular array. It has the advantage of not requiring any modification to the full-core diffusion code for its implementation. For LWRs, SPH establishes neutronic equivalence between detailed-geometry heterogeneous fuel-pin cells and homogenized fuel-pin cells by adjusting homogenized multigroup macroscopic cross sections and diffusion coefficients. This work investigates the possible use of the SPH methodology for Pressurized Heavy-Water Reactor (PHWR) lattices whose fuel pins are arranged in concentric rings rather that in a rectangular array. Results for single-node as well as multi-node lattice-calculation models are presented. Results show that, with proper region definition, the SPH methodology can be used for PHWR lattices but that improvement in homogenization accuracy is only marginal compared with standard homogenization when comparing results for the same type of lattice model (single-node or multi-node).