Blanket Research & Development
The fusion blanket is a component that surrounds about 90 percent of the burning plasma and will absorb the high-energy neutrons emitted from fusion reactions in the plasma. This component is also responsible for breeding one of the fuels, tritium, by exposing lithium-bearing compounds inside the blanket to the fusion neutrons. The third major role of the blanket is to provide some shielding of the neutrons to protect components behind it. The blanket will reside in the same vacuum that the plasma operates in, and it will have a plasma-facing part to its design requiring high heat flux and plasma exposure features. Fluids will flow into and out of the blanket to cool it and take the power to a thermal conversion system to make electricity.
The blanket typically has a structural material and potentially a number of functional materials. The global material science community has developed reduced activation ferritic martensitic (RAFM) steel as the baseline structural material with some advanced variants for a longer neutron irradiation lifetime. Functional materials can include solid tritium breeders (lithium ceramic oxides), electrical and/or thermal insulators, corrosion coatings or surface modifications, or tritium permeation barriers. If the tritium breeder material is a liquid it will travel through the blanket. All these materials are exposed to neutrons and will progressively degrade due to damage and gas production inside the material’s matrix. In addition, the blanket will have heating and stresses, hydrogen in its matrix, and strong background magnetic fields along with gradients in all these parameters. The engineering design of blankets is enormously challenging. Finally, these components will have lifetimes of approximately 2-5 years before having to be replaced.
Blanket R&D is focused on single to few effect phenomena such as liquid metal tritium breeder corrosion and thermo-fluids behavior, solid tritium breeder irradiation response, and advanced manufacturing, advanced helium cooling designs to optimize thermal performance, multi-physics design of blankets (neutronics, thermo-mechanics, computational fluid dynamics, liquid metal CFD, tritium mass transport, materials, thermal hydraulics, and plasma physics).