Feasibility of a novel approach for fast, economical determination of radiation damage in nuclear reactor cores. Final report, November 1, 1992--October 31, 1996

摘要

The objective of this program was to verify that proton irradiation can be used to study neutron irradiation effects in light water reactors, and to use protons to gain a better understanding of the IASCC problem. The objective was met by studying the role of proton irradiation in three physical phenomena; radiation induced segregation (RIS), microstructure evolution and stress corrosion cracking. RIS studies showed that the diffusivities of the major alloying elements of austenitic stainless steels, Fe, Cr and Ni, are composition dependent which affects the amount of grain boundary segregation, ordering strongly affects segregation in austenitic iron- and nickel-base alloys, and the mechanism of RIS in Fe-Cr-Ni alloys is the inverse Kirkendall effect, specifically the coupling between alloying elements and the vacancy flux. The result of this work was the formulation of an improved, or modified inverse Kirkendall model which accounts for composition-dependent diffusion parameters which provides it with a significant improvement in the ability to predict grain boundary compositions in irradiated alloys. The microstructure and deformation study showed that proton irradiation results in the formation of dislocation channels upon subsequent straining at 288(degrees)C. This is consistent with results for neutron irradiation. These channels concentrate slip into localized sets of slip planes. However, by themselves, they cannot induce intergranular cracking. An aggressive environment is required for IG crack formation.