Densification-induced strains in 20% cold-worked 316 stainless steel during neutron irradiation

A correlation has been developed to describe the densification and resultant strains of 20 percent cold-worked 316 stainless steel fuel pin cladding during neutron irradiation at elevated temperatures. The correlation describes the mean density change as a function of time, temperature and carbon content. The densification arises from the recovery of deformation-induced strains and the precipitation of various secondary phases. The major portion of the densification occurs prior to the formation of radiation-induced voids and is independent of the swelling phenomenon. The densification process is similar in both N-lot and first core heats of steel. The resultant strains indicate that the process is anisotropic with the length change larger and the diameter change smaller than expected for isotropic deformation.