Round Robin High Temperature Oxidation Tests at KIT

Various concepts of enhanced accident tolerance fuel (ATF) cladding have been proposed and extensively studied worldwide to replace the Zr alloy cladding in water-cooled nuclear reactors. Four alternative ATF cladding materials, i.e. austenitic steel AISI348 (Fe₁₈Cr₇Ni), Cr coated Zircaloy-2, Cr/Cr2AlC coated Zircaloy-4 and SiCrZr coated Zircaloy-2, and a reference Zircaloy-4 were tested in high-temperature steam at three individual temperatures and times. The AISI348 steel has poor oxidation resistance with a Fe-based double-layered oxide scale. Growth of a Cr2O3 layer on Cr coating protected the substrate from oxidation up to 1300°C for short time. Enhanced oxidation resistance was also seen for Cr/Cr2AlC and SiCrZr coatings. However, the Cr/Cr2AlC coatings were prone to cracking and thin SiCrZr coatings were quickly fully oxidized at tested temperatures (1100°C and above). (author)