Prediction Methods to Account For The Effect of Pressure-Tube Diametral Creep On Critical Heat Flux and Pressure Drop For A 37-Element Bundle String

Abstract

Prediction methods have been derived to account for the effect of pressure-tube creep on critical heat flux and pressure drop in 37-element CANDU-type bundles. These prediction methodologies are based primarily on an analogy with eccentric annuli to account for the effect of a change in local bundle eccentricity resulting from an enlargement of the pressure-tube diameter. The methodologies have been validated with experimental data recently obtained in tests with both uncrept and crept channels at Stern Laboratories. These tests employed a flow channel having an axially varying pressure-tube diameter with a maximum value 3.3% larger than the diameter of an uncrept channel. The present methodologies predict the dryout power in crept channels with an overall average error of0.42% and a root-mean-square error of 3.77%, and the total channel pressure drop with an overall average error of-0.65% and a root-mean-square error of 4.38%.