Pin-by-pin fuel assembly coupling for North Anna PWR using Serpent and Flownex

Abstract

This study examines the pin-by-pin fuel assembly numerical coupling of Neutronics (N) and Thermal-hydraulics (TH) in the North Anna Power Station (NAPS) Pressurized Water Reactor (PWR) core simulations to improve predictive accuracy in reactor behaviour analysis. The research focuses on developing a computational model that enhances power distribution calculations by incorporating temperature feedback effects. An external serial integration coupling strategy was applied to both the average fuel assembly and the hottest fuel assembly, utilizing Serpent for N and Flownex for TH. Results indicate that including temperature-dependent feedback yields a more accurate representation of variations within the two fuel assembly models, with standard deviations computed across all iterations of the defined fields remaining below or marginally exceeding the established convergence criterion. These results highlight the importance of coupled fuel assembly simulations in optimizing reactor safety and performance. Future research will concentrate on improving data transfer efficiency and reducing computational time for simulations.