Fuel-Cladding Compatibility in Metallic Nuclear Fuels

In advanced nuclear systems, the chemical compatibility of the fuel and cladding is imperative for safe operation of a reactor. Therefore, it is essential to limit the interdiffusion between the fuel and cladding. To better understand the compatibility of metallic fuel and cladding at the highest possible operating temperatures in a sodium fast reactor, diffusion experiments were conducted at 700˚C using fuel alloys and various advanced stainless steel claddings that would be employed at these high temperatures. The various annealed diffusion couples were analyzed using scanning electron microscopy to investigate the kinetics of the fuel-cladding interactions and to identify the types of phases that formed. Relatively large diffusion zones were observed for some of the couples between metallic fuel and cladding samples. In some cases, specific phases appeared to melt. In the cases where large diffusion structures were not observed, a surface layer was present in the fuel alloy that appeared to impede interdiffusion