Development of Enhanced Accident Tolerant LWR Fuel Cladding

In comparison with the standard UO₂-Zr alloy system which is currently used in the LWRs, enhanced accident tolerance fuels (ATF) can tolerate loss of active cooling in reactor core for a considerably longer time period during design-basis and beyond design-basis event while maintaining or improving the fuel performance during normal operations and operational transients. As the ATF cladding concepts, coating cladding, Mo-Zr cladding, FeCrAl cladding, and SiC/SiCf cladding have being developed in many countries. Regarding the cladding performance, new fuel cladding concepts will be evaluated with respect to the accident scenarios and specific plant designs for LWRs and fuel cladding fabrication facilities. After the consideration of various performances in accident and normal conditions, the coating cladding concept was selected to apply an ATF cladding in this study. A surface modified cladding as a new concept is suggested to apply an enhanced accident tolerance fuel cladding. The key technologies of new concept were consisted of the partial ODS treatment and surface coating. The aim of the partial ODS treatment is to increase the high temperature strength to suppress the ballooning/rupture behavior of fuel cladding during accident event. The target of the surface coating is to increase the corrosion resistance during normal operation condition and to increase the oxidation resistance during accident event