Research on rare-earth element reaction processes with fuel cladding materials in FBR

Reaction tests of diffusion couple of ferritic martensitic steel (PNC-FMS), a candidate for fast reactor fuel cladding, and the rare-earth element Ce by diffusion pairing have been performed for up to 600 h. The results indicated that the reaction process is diffusion-controlled. Chemical and microstructural analyses by SEM and TEM revealed that Ce₃(Fe, Cr)₂₉ was formed in the early stage of the reaction, which was subsequently converted into CeFe₂. The reaction phase changed depending on the presence of Cr in the base metal and increasing Ce concentration, indicating a multi-reaction process. (author)