Decay Chain and Shelf Life
Tritium's 12.3-year half-life means stored fuel steadily converts to helium-3; the same decay that ages the tritium creates the second product.
One decay, two consequences
Tritium has a half-life of 12.3 years, decaying by beta emission to stable helium-3. This single fact governs both the shelf life of stored tritium and the production of the helium-3 coproduct — they are the same process viewed two ways.
As a shelf-life issue, decay means tritium in storage loses about 5.47% of its mass to helium-3 each year. A batch held for years is measurably depleted, and the helium-3 that forms mixes with the tritium and must be separated before the tritium is used or shipped, because helium-3 is a strong neutron absorber and a fuel contaminant if left in.
The decay arithmetic
- Half-life: 12.3 years (T → ³He + β⁻ + ν̄)
- Decay constant λ ≈ 0.0563 / yr
- Annual conversion ≈ 5.47% of held mass
- Maximum beta energy ≈ 18.6 keV (low, easily shielded)
Turning a liability into a product
Because the decay is unavoidable, the foundry treats the resulting helium-3 as a deliberate coproduct rather than waste. Storage and processing are designed to collect the helium-3 cleanly during the same separation that keeps the tritium pure. The ~1.97 kg/yr helium-3 figure is the harvested result of this shelf-life process across the standing inventory.
The decay chain ends at stable helium-3 — there is no further radioactive daughter, which is part of why the material is attractive and safe to handle.
This page describes a design-and-simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind (FOAK) first tritium is targeted near 2030. No net-gain claim is made before FOAK.