Simulation and Analysis of Bearing Pad to Pressure Tube Contact Heat Transfer under Large Break LOCA Conditions

Abstract

In some postulated loss-of-coolant accidents (LOCAs) in a CANDU reactor, localized "hot spots" can develop on the pressure tube as a result of decay heat dissipation by conduction through bearing pad pressure tube contact locations. Depending on the severity of flow degradation in the channel, these "hot spots" could represent a potential threat to fuel channel integrity. The most important parameter in the simulation of BP/PT contact is the contact conductance. Since BPIPT thermal contact conductance is a complex parameter which depends upon the thermal and physical characteristics of the material junction and the surrounding environment, contact conductance is determined from experiments relevant to the reactor conditions. A series of twelve full scale integrated BPIPT contact experiments have been conducted at AECL- WRL under Candu Owner Group (COG). The objective of the experiments was to investigate the effect of BPIPT contact on PT thermal-mechanical behaviour. This paper presents the simulation of the BPIPT interaction integrated experiments using SMARTT and MINI-SMARTT computer codes and subsequent derivation of the BPIPT contact conductance by best film of the experimental pressure tube temperature measurements.