Wall Effect Analysis Based on Subchannel Decomposition Method

When doing experiments with repeated structure elements, it is a routine to select part of it due to the limit of experimental cost and condition. This part of structure has differences with the original structure because of the wall effect in thermal hydraulic characteristics. In this study, a method to analyze the wall effect was proposed based on the subchannel decomposition idea. This method could be used as a rough prediction of experimental structure selection. In the geometrical parameter optimization of typical structure for CSR1000 rod assembly, the comparison with CFD results confirmed its validity. The typical analysis of 5×5 rod array was also performed with this method and it suggested that such structure was a balance choice between the wall effect and experimental cost.