A Prediction Method For The Effect of Radial Heat-Flux Distribution on Critical Heat Flux in CANFLEX Bundles

Abstract

A generalized prediction method has been derived for predicting the effect of radial heat-flux distribution (RFD) on critical heat flux (CHF) in CANFLEX bundles. The ratio of CHF for the RFD of interest to that for the optimum RFD of the CANFLEX fuel bundle is expressed in terms of a bundle imbalance factor. The optimum RFD for the CANFLEX fuel bundle has been established with available CHF data of various RFDs. The variation of CHF ratios with bundle-imbalance factor has been verified against experimental values for 37-element and CANFLEX bundles. An assessment of the prediction method has been performed using CHF data obtained with a CANFLEX bundle simulating the 1.6% slightly enriched uranium (SEU) fuel RFD. Good agreement of predicted and experimental CHF values has been observed. On average, the experimental CHF ratio is 0.94, as compared to the predicted CHF ratio of 0.93 between the 1.6% SEU fuel RFD and natural uranium fuel RFD.