Tritium Breeding Ratio — The Materials View
Reaching a local TBR of 1.8 leans on enrichment, multiplication, and near-complete coverage; the gap to realistic net breeding is an open question.
TBR as a materials outcome
The tritium breeding ratio is the product of many materials choices: lithium-6 enrichment, neutron multiplier quantity and placement, blanket thickness, and how completely the blanket wraps the plasma. The breeder treats TBR as a design lever across 1.1, 1.5, and 1.8, each demanding progressively more from the materials and geometry.
The open reconciliation
A design can achieve a high TBR in an idealized calculation with full coverage and no losses. The realistic machine has penetrations for heating, diagnostics, and maintenance, plus tritium losses in extraction. The gap between a local TBR target of 1.8 and the net TBR after coverage gaps and losses is an open question the breeder states plainly. Tritium self-sufficiency is not yet proven.
- Enrichment, multiplier, and thickness raise local TBR.
- Penetrations and losses lower net TBR below the local value.
- Net self-sufficiency at TBR 1.8 is unproven, not assumed.
- This is the breeder's largest single open reconciliation.
We publish the target and the gap together. Claiming self-sufficiency before it is demonstrated would misrepresent the design's status.
No single number closes it
Because TBR emerges from enrichment, multiplication, thickness, coverage, and recovery acting together, no single material change closes the gap between the local target and net self-sufficiency. The breeder therefore treats TBR as a coupled optimization with an explicit, published shortfall rather than a solved figure, which is the honest state of the design today.
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.