New class of tritium breeders for fusion applications: Metal-reinforced composite breeders

Commercial fusion reactors operating on a deuterium–tritium (D–T) fuel cycle will require a steady supply of tritium to maintain the burning plasma required for continuous power generation. Tritium is most easily produced by surrounding a fusion reactor core with a breeder material containing lithium (Li), which reacts under the intense neutron flux leaving the reactor core to form tritium and helium. Unfortunately, most of the liquid breeders historically considered are exceedingly corrosive to reactor structural materials, while many solid (ceramic) breeders are forced to make tradeoffs between Li content and mechanical integrity. In this work, a new class of solid tritium breeders is developed to break the historic limit between Li-density and mechanical integrity of traditional solid breeders: metal-reinforced composite (MERC) breeders. Specifically, the high Li-density of lithium oxide (Li 2 O) is exploited through the addition of a metal reinforcing phase, producing a composite breeder material that exhibits high strength and quasi-ductility with a Li-density greater than other leading solid breeder candidates, including lithium orthosilicate (Li 4 SiO 4 ) and lithium metatitanate (Li 2 TiO 3 ). Mechanical testing, microstructural characterization, and results of neutronic simulations investigating the potential tritium breeding ratio (TBR) are presented and discussed considering blanket design implications for future fusion energy systems. • New class of tritium breeder materials has been synthesized for the first time. • Metal-reinforced composite breeders made containing lithia and iron phases. • New composite breeders exhibit superior mechanical properties to ceramics. • Simulations predict high tritium breeding potential in composite breeders. • Composite tritium breeders stand to break typical strength–productivity tradeoff.