Fusion Technology Development for DEMO in the Broader Approach Activities

As a part of the Broader Approach activities from 2007 to 2016, research and development on blanket related materials and tritium technology have been initiated toward DEMO by the EU and Japan. According to the common interest of EU and Japan toward DEMO, R&D on reduced activation ferritic martensitic (RAFM) steels as a DEMO blanket structural material, silicon carbide composites (SiCf/SiC), advanced tritium breeders and neutron multiplier for DEMO blankets, and tritium technology will be implemented as a part of the DEMO Design and R&D coordination Center activity of BA. As a preparatory work on the RAFM steels, a 5-ton heat of RAFM steel (F82H) was procured recently, which control of indicated that unexpected impurities was important in the large scale of RAFM steels. Double notch tensile tests to evaluate failure behavior were performed for NITE-SiCf/SiC composites with different size and different notch depth. It was found that neither significant notch sensitivity nor specimen size effect was observed in proportional limit tensile stress and fracture strength, implying the importance of the stress (or strain) criterion for the failure evaluation of composites. On the neutron multiplier, reactivity of Be-Ti and Be-V alloys with F82H was investigated. The reactivity of the Be-Ti and Be-V alloys was much smaller than that of pure beryllium. Large rods (about 30 mm in diameter) of Be-Ti were fabricated successfully. As a preliminary activity, Li4SiO4 pebbles were fabricated by the melt spraying method, and then characterized.