Charpy impact tests were conducted on 12Cr-1MoVW steel after irradiation in the fast flux test facility (FFTF) and the Oak Ridge research reactor (ORR). One-half-size and one-third-size Charpy specimens were irradiated in FFTF at 365°C. After irradiating half-size specimens to ̃ 10 and 17 dpa, a shift in ductile-brittle-transition temperature (DBTT) of 160°C was observed for both fluences, indicating a saturation in the shift. A shift in DBTT of 151 °C was observed for the one-third-size specimens after irradiation to 10 dpa. One-third-size specimens of 12Cr-1MoVW steel irradiated to ̃7 dpa in the ORR at 330 and 400°C developed shifts in DBTT of 200 and 120°C, respectively, somewhat above and below the shifts observed after irradiation at 365°C in FFTF. This correspondence of results in the mixed-spectrum ORR and the fast-spectrum FFTF is in marked contrast to large differences observed between specimens irradiated in the mixed-spectrum high flux isotope reactor and the fast spectrum experimental breeder reactor.
The first data on the effect of fast reactor irradiation on the impact behavior of 2¼Cr-1Mo steel were obtained. One-third-size specimens were irradiated in FFTF to ̃ 10 dpa at 365°C. An increase in DBTT of 170°C was observed, similar to the shift observed for 12Cr-1MoVW steel following comparable irradiation. The reduction in the upper-shelf energy for the 2¼Cr-1Mo steel was less than that observed for 12Cr-1MoVW steel. Because of the low DBTT of unirra-diated 2¼Cr-1Mo steel, the DBTT after irradiation remained below that for 12Cr-1MoVW steel.