SiC/HT-9 MMC Composite Tubes for Fuel Cladding

73043S03-I The cladding of fuel rods for Gen IV nuclear reactors must operate under extremely harsh conditions: high temperature (up to 1000 C in some designs), radiation damage from both fast and thermal neutrons, and attack by corrosive liquids (sodium and lead in some designs). The properties of the materials used today for fuel cladding significantly limit the design options and performance for most Gen IV reactor concepts. This project will fabricate a composite tube containing layers of SiC-fiber cloth and HT-9 steel. The SiC fibers will provide strength reinforcement and extreme resistance to neutron damage; the HT-9 steel will provide a ductile support matrix. Full impregnation and surface bonding between the ceramic cloth and the steel matrix will be achieved using two proprietary steps: (1) applying an adhesion layer to the fibers prior to assembly of the composite, and (2) hot-drawing the lay-up composite through a SiC die set while the tube is inductively heated locally to near-melt of the steel. Corrosion resistance will be provided by bonding a thin Ta layer to the outer surface of the tube. Phase I will develop all process steps and fabricate the first samples of the composite tube. The samples will be sanctioned, and the bonding of the fibers within the steel matrix will be evaluated. A plan for scaling-up the fabrication process, to produce tubes with dimensions appropriate for fuel cladding in Gen IV reactor designs, will be developed. In Phase II, prototype tubes will be tested under conditions similar to those in a Gen IV reactor core (temperature, neutron flux, corrosion, internal swelling). Commercial Applications and Other Benefits as described by awardee: The technology should have immense commercial potential because the ceramic-steel composite could be prepared as flat sheets as well as tubes. It would be a material of choice for any application requiring combinations of high strength, high temperature performance, corrosion resistance, and resistance to radiation damage. Applications include high-temperature reaction vessels in chemical synthesis, metals manufacturing, airfoils, turbines, engines, spacecraft, artillery tubes, armor, targets for particle accelerators, and first-wall structures in fusion reactors.