Characterization of phases formed between U–Pu–Mo fuels and Fe–12Cr cladding

Abstract Exposure to high temperatures and irradiation can lead to interaction between fuel and cladding constituents, inter-diffusion, and formation of brittle or low-melting phases. Therefore, understanding of fuel-cladding interaction (FCCI) is critical for evaluation of fuel performance in a reactor environment. In this contribution, phases formed between U–22Pu–4Mo and U–25Pu–15Mo (in wt%) fuel alloys and Fe–12Cr cladding were characterized using scanning and transmission electron microscopy (SEM/TEM) techniques. Phases formed within FCCI layers in both alloys were identified by implementing selective area diffraction pattern analysis as Cr 0.3 Mo 0.7 (Im-3m), Fe 2 U (Fd-3m), UCrFe (Fd-3m), and Fe 2 Pu (Fd-3m). Phases formed at the end of the FCCI layer in the U–22Pu–4Mo alloy included UCrFe (Fd-3m), Fe 2 U (Fd-3m), and Cr 2 FeO 4 (Fd-3m) while in the U–25Pu–15Mo alloy the phases were consistent with Cr 0.49 Fe 0.51 (P4 2 /mnm), Cr 0.8 Fe 0.2 (Im-3m), and UCrFe (Fd-3m).