Blanket Structural Material
The steel that holds the blanket together must survive neutron damage, high temperature, and coolant chemistry while staying low-activation.
The unglamorous critical part
Behind the breeder chemistry sits ordinary-looking structure: the metal that contains the lithium, multiplier, and coolant and holds the blanket's shape. It must survive intense neutron damage, run hot, resist corrosion from the coolant and breeder, and — importantly — activate little so that waste and maintenance stay tractable. Reduced-activation ferritic-martensitic steel is the reference class.
Why low activation
Structural steel that activates strongly becomes long-lived waste and makes remote maintenance harder. Reduced-activation alloys substitute elements that decay quickly for those that produce long-lived isotopes, so components can be handled and disposed of more readily. This is a materials-chemistry choice with direct maintenance and waste consequences.
- Neutron damage drives swelling, hardening, and embrittlement.
- High operating temperature demands creep resistance.
- Coolant and breeder chemistry drive corrosion limits.
- Reduced activation eases waste and remote handling.
Structural-material behavior under a representative 14 MeV spectrum is an open qualification question shared with the whole field, and the breeder treats it as such.
Weldability and joining
The structural alloy must also be weldable and remotely joinable, because blanket modules are assembled and, over life, replaced. An alloy with excellent irradiation resistance that cannot be reliably welded or remade in a hot cell is impractical, so fabrication and maintenance properties sit alongside strength and activation in the selection.
This page documents a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. Figures are computed, reproducible targets, not measurements.