High Temperature Corrosion of Materials in Supercritical Water and Liquid Lead-Alloy Environments

Abstract

The Supercritical Water-cooled Reactor (SCWR) and Lead-cooled Fast Reactor (LFR) are among the six reactor concepts identified by the Generation IV initiative for the next generation nuclear reactors. Materials degradation due to corrosion is a significant issue in both supercritical water and molten lead (-alloy) environments, particularly at the intended higher temperatures of application. In supercritical water, corrosion of ferritic and austenitic steels and Inconel alloys occurs mainly by the growth of an oxide layer on the surface. In molten lead (-alloy), corrosion can occur by dissolution of the material, oxidation, or by the penetration of liquid metal into the material primarily along the grain boundaries. Surface treatment of ferritic steels by the incorporation of thin film of oxidation-resistant materials has been shown to mitigate corrosion in these aggressive environments. Grain boundary engineering (GBE) reduces spallation of oxide layers in austenitic steels in supercritical water environment.