A comparative analysis of detailed and reduced CFD approaches to model wire-wrapped fuel bundles for LMFBRs applications

• Fine and coarse CFD analysis of 19 rod wire-wrapped fuel bundle is performed. • A simplified models namely Porous-Wire and Solid-Wire are developed to investigate heat transfer within wire-wrapped fuel bundle. • A model-to-model comparison is conducted, and validation against the experimental data is performed. The paper investigates the capabilities of different CFD modelling approaches in reproducing operating conditions relevant for Liquid Metal Fast Breeder Reactors technologies. The selected benchmark is the NACIE-UP facility wire-wrapped fuel bundle using Lead-Bismuth Eutectic (LBE) as coolant: the predictions are compared to the experimental data collected for several operating conditions considered in the frame of two distinct experimental campaigns. Four different modelling approaches have been adopted in this work to model the NACIE-UP Fuel Pin Simulator: Bare, Detailed, Solid-Wire and the Porous-Wire Rod Bundle model. A model-to-model comparison is performed to understand the benefits, limitations, and accuracy of using different modelling approaches for representing wrapped wires fuel bundles. Furthermore, integrating NACIE-UP benchmark experimental data into the comparative analysis reinforce the validation process of the adopted modelling approaches.