RAPHAEL: Synthesis of achievements on materials and components and future direction

The RAPHAEL Project (ReActor for Process Heat, Hydrogen And Electricity Generation) has been launched in 2006 within the European Union Framework Programs (FPs) to consolidate and advance HTR and VHTR technology within Europe. It is now completed after 5 years of fruitful collaboration between more than 35 partners. This paper reviews main achievements of RAPHAEL in the areas of materials and components, and sets out the remaining issues and priorities for future framework actions taking into account of the likely feedback from GIF (Generation IV International Forum) and its priorities and EU cross cut actions.For the vessel technology the program focused on one high temperature resistant material (Mod 9Cr 1Mo steel) formerly used in heat exchangers and comprised tests on first fabrications (thick section welds) including investigations on the effects of irradiation, thermal ageing and consequences of creep (at 450 °C) just above the material limit. The high temperature metals work looked at high strength Ni-based alloys and more advanced materials for greater creep strength. The non-metallic work on graphite and composites involved an extensive irradiation program at different temperatures on new graphites, examining their potential for block type and pebble bed type designs. Information on behaviour and physical representative property data was obtained. The graphite and composite program also included corrosion tests and micro-structural modelling developments.For the components, work focused on heat exchanger development including tests on fabricated features and mock-ups and loop testing at representative conditions. Also investigated were the behaviour of innovative bearings for the primary gas circulator, as well as blower and motor optimizations. Testing under controlled environmental conditions was also performed at temperatures up to 1000 °C to evaluate the behaviour and tribological performance of different graphite grades relevant to the reactor systems and core.