Improved cladding materials are needed for better structural stability in the corrosive high-pressure, hot-water environment of light water reactors, not only to extend fuel rod lifetime and increase fuel utilization (i.e., burn-up), but also to stave off run- away, active oxidation and melting of the rods under loss of coolant conditions. Proposed program will develop the use of a ceramic adhesive to bond monolithic silicon carbide (SiC) end caps to hybrid monolithic SiC/SiC-SiC CMC fuel cladding. The ceramic adhesive will be derived from liquid-polymer precursors to amorphous silicon carbide, and zirconium boride (SiC +ZrB2) and bulk ceramic powders. The resulting bond using this paste will have tensile strengths over 4000 psi and will be completely hermetic. Computer modeling will be used to discover optimum end cap design. Monolithic SiC tubes will be bonded to a SiC end cap as a proof of concept. Phase I will demonstrate bond strength, hermeticity, and corrosion resistance after extended periods in simulated reactor conditions (350 C, 2500 psi steam in autoclave). Commercial Applications and Other
Benefits: Next generation coatings will extend fuel rod lifetime allowing nuclear plants to run longer before having to undergo the expensive downtime of refueling their reactor. This will allow lower cost of delivered electricity improving the bottom line for the plant itself as well as the cost of electricity consumers will pay.
