Effects of Diffusion Barriers on the Fuel/Cladding Interaction of SFR Metallic Fuel

U-Pu-Zr metallic fuels have been developed as a fuel for a sodium-cooled fast reactor (SFR). In order to transmutate the long-lived minor actinide (MA) fission products such as Np, Am, Cm in spent fuel, transuranic element (TRU) bearing metallic fuel is being developed for a advanced burner reactor (ABR) or a advanced recycle reactor (ARR). One of the performance limiting factors of the metallic fuel is a fuel-cladding chemical interaction (FCCI) during irradiation. FCCI limits the fuel temperature due to a eutectic melting of interaction products at a temperature much lower than a melting point of a fuel alloy. Fuel cladding interaction behaviors of U-Pu-Zr alloys against Fe, Fe-Cr, D9 and HT9 have been investigated by out-of-pile annealing tests of their diffusion couples. Recently, usage of a thin coating on the inside wall of a cladding as a diffusion barrier has been proposed in order to suppress the interaction between metallic fuel and a cladding. Tokiwai et al. showed that Zr liner suppressed interdiffusion of U and HT9. Keiser and Cole showed that Zr and V did not react actively with uranium in out-of-pile annealing tests of simulated metallic fuels(U-Pu-Zr-Nd-Mo-Ru) and Zr or V liner metals. In this study, interdiffusion behaviors of U-Zr and U-Zr-Ce alloys (U-Zr-X) against FMS disks were investigated by observing the microstructures of the diffusion couples after out-of-pile annealing tests. In order to evaluate the diffusion barrier performance of metallic foils, Ti, V, Cr, Zr, Nb and Mo foils were inserted between the U-Zr-X and FMS