Blanket Materials

Lithium is the tritium breeder and a neutron multiplier boosts the neutron economy; together with coolant and structure they set breeding performance.

The material system

A breeding blanket is a designed material system, not a single substance. Its essential ingredients are a lithium-bearing breeder in which neutrons produce tritium, a neutron multiplier that increases the number of neutrons available for capture, a coolant to remove heat, and structural material to hold it all in the neutron environment. Their arrangement and proportions set the tritium breeding ratio.

Lithium and the breeding reactions

Tritium is bred when neutrons react with lithium; the lighter lithium isotope reacts strongly with slower neutrons, while the heavier one reacts with fast neutrons and releases another neutron. Enrichment and the neutron energy spectrum in the blanket therefore matter to breeding yield. Helium is a natural product of these reactions, which ties into the machine's helium-3 output.

Multiplication and the constraints

Because some neutrons are inevitably absorbed by structure, coolant, and lost through penetrations, a multiplier is generally needed to push the breeding ratio above one. Every gram of structure and every port is a neutron sink that competes with breeding. The materials must also tolerate 14 MeV neutron damage, high temperature, and, for tritium, low permeation losses. Choosing and validating this material set under realistic irradiation is central to closing the self-sufficiency question.

• Lithium breeder: tritium from neutron capture on lithium
• Neutron multiplier lifts the neutron economy above unity
• Structure, coolant, and ports are competing neutron sinks

This page describes a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030.