Low Conductivity SiC-Based Ceramic Composites for Fusion Blanket Flow Channel Inserts

Dual-coolant blanket designs for fusion reactors currently under development benefit from flow channel inserts that possess low electrical conductivity and low thermal conductivity. Such flow channel inserts will advance the state of fusion technology closer to producing continuous low cost, non-polluting power. In addition to low electrical and thermal conductivity, the desired properties of the flow channel insert are compatibility with lead-lithium breeder/coolant, stability under a high neutron flux, and mechanical robustness. Silicon carbide fiber-reinforced silicon carbide matrix composites have been shown to meet all of these requirements with the exception of the thermal conductivity requirement. The Phase I results indicated that an engineered approach is more viable at achieving all of the requirements for the flow channel insert compared to a chemical modification of the material, which resulted in a reduced thermal conductivity, but not of the required magnitude. The Phase II project will optimize an architecturally engineered SiC/SiC design for thermal, electrical and mechanical performance. This optimization will include modeling and experimental measurements of the targeted properties as well as an additional emphasis on maintaining impermeability to the lead-lithium coolant over time and varied operating conditions. The Phase II effort will also produce flow channel insert sub-elements for exposure to through-thickness temperature gradients including molten lead-lithium. Commercial Applications and other Benefits as described by the awardee: The proposed technology is an enabling materials technology on the long- term path to deploying fusion energy systems. However the development of a high temperature, radiation compatible material can also be utilized near term in fission reactors currently under development. Such advancements also have implications for numerous applications in the aerospace industry for structural thermal protection systems.