Synergistic influence of displacement rate and helium/dpa ratio on swelling of Fe–(9, 12)Cr binary alloys in FFTF at ∼400 °C

Contrary to the behavior of swelling of model fcc Fe–Cr–Ni alloys irradiated in the same FFTF-MOTA experiment, model bcc Fe–Cr alloys do not exhibit a strong dependence of swelling on dpa rate at ∼400 °C. This is surprising in that an apparent flux sensitivity was observed in an earlier comparative irradiation of the same Fe–Cr binaries conducted in EBR-II and FFTF. The difference in behavior between the two experiments is ascribed to the higher helium generation rates of Fe–Cr alloys in EBR-II compared to that of FFTF, and also the fact that lower dpa rates in FFTF are accompanied by progressively lower helium generation rates.