Computational Fluid Dynamics Investigation of the Impact of 6% Crept Pressure Tubes on Flow Behavior, Fuel Temperatures, and Pressure Tube Wall Temperatures of a Single CANDU 37M Fuel Bundle

Abstract

A Computational Fluid Dynamics (CFD) simulation with heat transfer was carried out in this work on a single CANDU 37M fuel bundle sitting in a pressure tube that has experienced 6% diametral creep. The investigation focused on the predicted coolant flow behaviour, fuel temperature, and pressure tube wall temperature to explore the effects of the crept pressure tube on these parameters. The findings reveal that around 29% of the coolant flow bypasses the bundle within the 6% crept pressure tube, resulting in a temperature difference of roughly 20 K between the fuel element positioned at the bottom compared to those at the top. Moreover, the temperature profile of the crept pressure tube wall was observed to be uneven, with the bottom exhibiting approximately 30 K higher temperature than the upper crept pressure tube wall.