Investigating Potential Accident Tolerant Fuel Cladding Materials and Coatings

Thermal energy release and hydrogen generation due to breakaway oxidation of Zr fuel cladding materials are of concern in accident scenarios involving extreme temperature increase (up to 1200 °C). As a result, potential accident tolerant fuel cladding (ATFC) materials and coatings are being investigated. Physical vapor deposited CrN coatings are considered as possible protective barrier materials for Zircaloys. In addition, Fe–Cr-Al alloys are considered potential candidate materials for ATFC due the formation of protective alumina at high temperatures which maintains resistance by preventing oxide breakdown. Both CrN-coated Zircaloys and a Fe–Cr-Al model alloy were exposed to 300 °C water and steam environments up to 1200 °C to evaluate their resistance to corrosion under normal reactor operating conditions and to high temperature steam oxidation. Surface analytical techniques are used to evaluate the effectiveness of oxides and/or coatings over the 300 °C water to 1000 °C steam temperature regime.