An Experimental Investigation Into the Development of Pressure Tube/Calandrla Tube Contact and Associated Heat Transfer under LOCA Conditions

Abstract

During postulated loss-of-coolant accidents in CANDU reactors with impaired emergency cooling, the pressure tube can become sufficiently hot to deform and make contact with its calandria tube. This paper describes a series of experiments performed to investigate the high temperature deformation of a pressure tube, its contact with its surrounding calandria tube and the subsequent heat transfer to a pool of water surrounding the calandria tube. The pressure tube was carrying an internal weight equivalent to that of the quantity of fuel that it would contain in a reactor. Experiments were performed at different heating rates and internal pressures. The temperature of the pressure tube at the time of contact is COP pared with values predicted using TRAN II and CREEPSAG, computer codes used in safety analysis to predict fuel-channel deformation.