The Performance of T-Pad Bearing Pads, as a Remedy Against Pressure Tube Crevice Corrosion, on Bundles Irradiated at Bruce and Point Lepreau

Abstract

Crevice corrosion in CANDU reactors can occur between the standard design fuel bundle bearing pads and the pressure tube when the element operates at a sufficiently high power to create the crevice boiling condition necessary for the concentration of lithium hydroxide leading to enhanced oxidation of the bearing pad and pressure tube. Since crevice corrosion was discovered in Picketing pressure tubes, a concerted effort has been made on design changes to the standard bearing pads in order to minimize/eliminate crevice corrosion. This development program led to the T-Pad bearing pad design. Recent demonstration irradiations of prototype bundles, fitted with T-Pad bearing pads, were conducted in Bruce and Point Lepreau Nuclear Generating Stations. The subsequent post-irradiation examinations indicated, that except for increased hydrogen and deuterium pickup in the T-Pads, the performance of the T-Pads and bundles is consistent with standard bearing pad bundles.