Radiation swelling behavior and its dependence on temperature, dose rate, and dislocation structure evolution

The microstructural evolution of high-purity steel under irradiation is modeled including a dislocation density that evolves simultaneously with void nucleation and growth. Analysis of the coupled microstructure sinks indicates the evolving dislocation density shapes the rate of void nucleation and the void size distribution so as to enhance steady-swelling behavior at high doses. The incubation dose, to roughly the point of transition to steady-state swelling, is closely related to and even controlled by evolution of the dislocation structure. Incubation is thus a strong function of both the irradiation temperature and the dose rate. The predicted swelling trends versus temperature, flux, and time are closer to experimental results than earlier calculations of void nucleation and growth with a fixed dislocation density.