CFD simulation of flow and heat transfer characteristics in a 5×5 fuel rod bundles with spacer grids of advanced PWR

TLDR

CFD simulations of nuclear reactor fuel assemblies provide high‑fidelity design and optimization, with validated models and user‑practice guidelines essential for reliable results. The study aims to refine user‑practice guidelines for rod‑bundle CFD by rigorously analyzing the MATiS‑H benchmark. A 5×5 rod‑bundle model for an advanced PWR was constructed and its three‑dimensional thermal‑hydraulic behavior was examined. Spacer grids and mixing vanes in the rod bundles induce strong lateral flow, raise pressure drop, and markedly enhance heat transfer, offering useful design guidance for advanced PWR fuel assemblies.

Abstract

High fidelity nuclear reactor fuel assembly simulation using CFD method is an effective way for the structure design and optimization. The validated models and user practice guidelines play critical roles in achieving reliable results in CFD simulations. In this paper, the international benchmark MATiS-H is studied carefully and the best user practice guideline is achieved for the rod bundles simulation. Then a 5 × 5 rod bundles model in the advanced pressurized water reactor (PWR) is established and the detailed three-dimensional thermal-hydraulic characteristics are investigated. The influence of spacer grids and mixing vanes on the flow and hear transfer in rod bundles is revealed. As the coolant flows through the spacer grids and mixing vanes in the rod bundles, the drastic lateral flow would be induced and the pressure drop increases significantly. In addition, the heat transfer is enhanced remarkably due to the strong mixing effects. The calculation results could provide meaningful guidelines for the design of advanced PWR fuel assembly.