Oxide Layers in Ni-doped FeCrAl Alloy in 320°C Radioactive Hydrogenated Water

•FeCrAl alloy with Ni dopant introduced was irradiated with 5.4 MeV protons in hydrogenated high temperature water to observe oxide formation.•Thin inner oxide layers were found on each sample in each exposure region with varying compositions.•Oxides on FeCrAl-Ni alloy grew faster and thicker in a 24-hour exposure period than FeCrAl alloy without Ni.•The presence of Ni in FeCrAl results in facilitated growth of Cr and al oxides in the inner layer with Ni accumulation present at the metal-oxide interface. Iron-chromium-aluminum (FeCrAl) alloys have been the interest of the international nuclear energy industry as an accident tolerant fuel cladding replacement to the Zircaloy cladding alloys due to their enhanced corrosion resistance in both normal operation and accident conditions in light water reactors. It is important to understand the corrosion behaviors of FeCrAl before deploying it to nuclear power plants. This study aims to investigate if the addition of a small amount of nickel (Ni) could stabilize the oxide layer by forming the Ni-bearing spinel oxide, such as NiFe2O4, and increase the stability of the oxide layer under irradiation conditions. Current results show that the outer oxide crystals formed on the irradiated FeCrAl-Ni sample surface became larger than that on the FeCrAl sample, which indicates that the Ni addition facilitates the growth of oxide layers and that the FeCrAl-Ni sample exhibited a protective inner oxide layer in the harshest irradiation environment, indicating that Ni improves the corrosion resistance of FeCrAl in radioactive hydrogenated water.