Study on Critical Power Prediction of BWR Fuel Assembly by Computed Fluid Dynamics

The current BWR fuel assembly has seven spacers for maintaining a constant gap between fuel rods. Spacer design has a significant effect on the thermal hydraulic performance of a BWR fuel assembly. The purpose of this study is to develop an accurate method for predicting the effect of spacer shape on critical power. The critical power prediction method combining the CFD code of droplet deposition rate and the conventional subchannel code was verified by the critical power data of 4×4 rod bundle with various spacer shapes. From the verification, this method was found to be effective for predicting the critical power change with the change of the spacer shape.