Thermal Analysis of Bearing Pad to Pressure Tube Contact Heat Transfer Using ABAQUS

Abstract

A small-scale experimental apparatus has been used to determine the bearing-pad to pressure-tube contact conductance under conditions that simulate those expected during a postulated loss-of-coolant accident with simultaneous loss of emergency core coolant (LOCA/LOECC). The finite- element program ABAQUS was implemented using a two-dimensional model of the experimental setup to determine values for the bearing-pad to pressure-tube contact conductance and contact heat flow as a function of the interface temperature, defined as the average of the bearing-pad and pressure-tube temperatures at the contact. The contact heat flow or an overall conductance is proposed to characterize bearing-pad to pressure-tube heat transfer. This overall conductance, defined as the heat flux through the bearing-pad to pressure-tube contact divided by the fuel-sheath to pressure-tube temperature difference, increases from 0.5 kW/(m2-K) at 300 degrees C to 5-6 kW/(m2*K) at 1100 degrees C fuel- sheath/pressure-tube average temperature.