TREATMENT OF IRRADIATION EFFECTS IN STRUCTURAL DESIGN CRITERIA FOR FUSION-REACTORS

From the standpoint of design criteria for fusion reactors, the most s ignificant issues stem from the irradiation-induced changes in materia l properties, specifically the reduction of ductility, strain hardenin g capability, and fracture toughness with neutron irradiation. Recentl y, Draft 5 of the interim ITER structural design criteria (ISDC), whic h provide new rules for guarding against such problems, was released f or trial use by the ITER designers. To account for irradiation effects under monotonic loading, the ISDC contains several new rules which pr ovide primary and secondary stress limits as functions of uniform elon gation and ductility. These new rules were derived from a simple model based on the concept of an elastic follow up factor which has been us ed extensively by the Japanese and French designers for analyzing cree p-fatigue problems in fission reactors. Detailed analytical and finite -element analyses were conducted and the results were compared with av ailable test data to determine the limitation of the rules as they rel ate to the loss of a material's ductility and strain hardening capabil ity. (C) 1998 Published by Elsevier Science S.A. All rights reserved.