Variation of Critical Heat Flux with Radial Power Profile in the Low-Void Reactivity Fuel for UNCREPT and 5.1% CREPT Channels

Abstract

An experiment has been completed to obtain CHF data using a horizontal, axially uniform-heated, CANFLEX LVRF bundle string cooled with Freon flow in uncrept and 5.1% (uniformly) crept channels. It covered three radial power profiles corresponding to the fresh and mid-burnup LVRF, and fresh CANFLEX NU fuel (similar to that of the discharge-burnup LVRF). Results showed that CHF values for the fresh LVRF profile are generally the lowest while those for the fresh CANFLEX NU fuel profile are the highest. CHF values for the LVRF profiles remain higher than those for the 37-element bundle. CHF ratios between LVRF (both fresh and mid-burnup) and fresh CANFLEX NU fuel profiles are slightly lower for the uncrept channel than the 5.1% crept channel. Good agreement has been observed between experimental CHF ratios and predictions from an existing correlation for the uncrept channel. The predicted ratios are lower than the experimental values for the crept channel.