Flow Channel Inserts for Dual-Coolant ITER Test Blanket Modules

The International Thermonuclear Experimental Reactor (ITER) is an international effort to build the first power-producing, agnetically-confined fusion reactor within the next decade. The reactor design requires the development of advanced materials for flow channel inserts that will accomodate a lead-lithium (Pb-Li) alloy, tritium-breeder exit temperature of ~700°C. The flow channel insert must have low thermal and electrical conductivity, resistance to thermally induced stress, impermeability, and non-reactivity with the Pb-Li alloy. This project will develop a sandwich structure for these inserts, using a previously-developed, high-specific-stiffness open-cell silicon carbide (SiC) foam with integrated, thin, dense SiC face sheets (80-90% porous). The structure not only will satisfy the above requirements, but also will be far more manufacturable, exhibit higher thermal stress resistance, and cost substantially less than SiC/SiC composites. In Phase I, a matrix of SiC-foam/SiC-facesheet, flow-channel insert specimens was fabricated, and thermomechanical modeling and liquid metal testing were performed. The modeling and test results indicated that the concept could meet the flow channel insert requirements. In Phase II, a 30-cm tall, flow-channel insert section (12×12 cm2 cross-section) will be designed and fabricated for testing with high temperature Pb-Li. The properties of the SiC foam/SiC facesheet insert first will be optimized through thermal, mechanical, and chemical testing. Test results will be incorporated with thermomechanical modeling to determine the optimal SiC foam density and foam/facesheet thickness. Performance will be demonstrated by subjecting components to an environment that simulates that of an actual flow channel insert. Commercial Applications and other Benefits as described by the awardee: Nuclear fusion is an ideal alternative to increasingly scarce and expensive fossil fuels, and can provide a much greater quantity of environmentally sound energy than wind, solar, and geothermal sources. The proposed flow channel insert should serve as a key component that would enable fusion reactors tol ultimately be used for large-scale commercial energy generation.