Irradiation effects on reduced activation ferritic/martensitic steels - Mechanical properties and modelling

Although reduced activation ferritic/martensitic steels (e.g., Japanese F82H) are leading candidate structural materials for DEMO blanket and ITER-TBM, irradiation by 14 MeV fusion neutrons produces severe damage in the steels to cause large changes of their properties. Results recently obtained by irradiation experiments about the life limiting properties (e.g., ductile to brittle transition temperatures and reduction of ductility) are briefly introduced. Also, Models of macroscopic behaviors, such as post irradiation tensile and fatigue properties are introduced, as well as the simulation methods of microstructural development under irradiation at relatively low temperatures. The macroscopic models have been obtained by the detailed analysis of strain distribution in the tensile specimen during post irradiation testing and that of the softening behavior during cyclic loading on irradiated fatigue specimen. These macroscopic models and the simulation methodology are essential for design criteria development for in-vessel components. (author)