Silicon Carbide Tritium Permeation Barriers for Steel Structural Components

The reactor design proposed by the United States for the International Thermonuclear Experimental Reactor (ITER) requires the development of advanced materials for breeder blankets. Although recently developed aluminide coatings for tritium permeation barriers work well in the laboratory, they fail in radiation environments. This project will explore the use of chemical vapor deposited (CVD) silicon carbide (SiC), which does not lose permeability resistance under radiation. The approach involves the development of a component that utilizes high-specific-stiffness CVD SiC foam, along with a thin, integrally bonded and fully dense SiC facesheet. This component will meet the requirements for tritium-permeation-barrier resistance to thermal- and radiation-induced stress, as well as impermeability to tritium, while offering higher thermal stress resistance, and lower tritium diffusivity and solubility, than currently used aluminide coatings. In Phase I, thermomechanical durability will be assessed through mechanical testing and thermal cycling. Sandia National Laboratories will define application requirements, establish a preliminary design, and perform tritium permeation testing. 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. Materials and structures that can withstand the demanding reactor environment will enable the next generation of fusion reactors to provide efficient electricity generation.