Investigation on subchannel flow distribution in wire-wrapped 37 and 61-pin bundle using computational fluid dynamics

Abstract

The wire-wrapped fuel bundle is commonly proposed in sodiumcooled fast reactors (SFRs) to enhance heat transfer of coolant in a compact triangular fuel array. In spite of its good performance, the wires around the fuel rods produce complex and periodic flow field, and it could eventually generate large uncertainties in design and licensing. In recent decades, the use of computational fluid dynamics (CFD) is gaining popularity to address this issue due to its capability to provide local flow and thermal information in large details. In this regard, CFD analyses have been performed here on the 37 and 61 pin SFR wire-wrapped fuel bundle experiment conducted at KAERI. The main purposes of this study are (1) to validate the CFD method in the SFR fuel bundle geometry, and (2) to investigate the local and the subchannel flow behaviors. First, the CFD simulations are compared with the experimental data and it is found that the applied models and the meshing schemes are good for prediction on the pressure drop and the mass flow rate for the given geometry. Afterward, the local flow data from the CFD is averaged for each subchannel in order to extract subchannel information. Then, the subchannel flow distribution characteristics are investigated and discussed using a flow split factor. Finally, this study proposes a model to predict the flow split factor in terms of subchannel types and wire rotation for the given wire-wrapped design.