Irradiation creep and swelling

Abstract

A rate theory of irradiation creep and volume swelling is presented. The volume swelling occurs at temperatures sufficiently high for void nuclei to be formed by the inert gas fission products; since dislocations absorb interstitials more readily than they do vacancies the voids are able to grow by a vacancy-diffusion mechanism. The volume swelling rate falls rapidly to zero when the thermal equilibrium concentration of vacancies becomes comparable with the irradiation-produced concentration.

The irradiation creep arises from the stress-induced inhomogeneity interaction between point defects and dislocations, which results in a stress-assisted climb of the dislocations. The creep rate is insensitive to temperature changes at low temperatures where swelling does not occur. In the swelling regime the creep rate increases with temperature.