Swelling and microstructure of high purity nickel irradiated with fast neutrons in EBR-II

The swelling of neutron-irradiated pure nickel in the annealed condition at ∼14 dpa is strongly dependent on irradiation temperature. However, nickel in various cold worked conditions does not exhibit this sensitivity, reaching a saturation level of swelling that is relatively independent of temperature. The tendency toward saturation is thought to be a consequence of nickel's high stacking fault energy which precludes the formation of partial dislocations with their stronger level of pinning. This leads eventually to a collapse in the dislocation population, resulting in an imbalance of sink strengths and a strong reduction in the void growth rate.