Uniform corrosion of FeCrAl cladding tubing for accident tolerant fuels in light water reactors

Iron-Chromium-Aluminum (FeCrAl) alloys are candidate materials for light water reactor accident tolerant fuel (ATF) rod cladding because of the unparalleled resistance of these alloys to attack by superheated steam in the case of a loss of coolant accident. Since FeCrAl alloys were never used before in a reactor environment, it was important to characterize their corrosion resistance under simulated reactor normal operation conditions. Tests were conducted for APMT and C26M alloys in three ~300°C water systems (two containing hydrogen and one containing oxygen). Results show that after 12 months of immersion the FeCrAl alloys lose a small amount of mass. The resistance to corrosion is mostly given by the development on the surface of a protective oxide mostly rich in Cr and Al. The mass loss was lower in APMT than in C26M because of the higher Cr content in the former. After 12 months residence in the ~300°C water, the FeCrAl specimens maintained their unequaled resistance to attack by 1200°C steam.