Irradiation creep-swelling coupling: microstructural modeling and data analysis

The irradiation creep behavior predicted by a model of microstructural evolution is compared with irradiation creep data on solution-annealed Type 304L stainless steel. These data are shown to be consistent with an irradiation creep-swelling coupling in which the swelling enhanced irradiation creep rate is proportional to the swelling raised to a power. The implications of this functional form for the irradiation creep-swelling coupling on the irradiation creep behavior of reactor components with time dependent stress and temperature histories, including the results to be expected from a comprehensive reactor history effects experiment, are discussed. The differences in the irradiation creep behavior of solution-annealed and cold-worked steels are investigated theoretically by incorporating the dose and temperature dependence of the line dislocation density into the microstructural model. This refinement of the microstructural model predicts that the ratio of the irradiation creep in cold-worked and solution-annealed steels will be dose dependent, the irradiation creep material constants will be temperature dependent, and below 5500C swelling enhanced irradiation creep will be the same in cold-worked and solution-annealed Type 316 stainless steel