The ~1.97 kg/yr Helium-3 Figure

The reference helium-3 coproduct rate near 1.97 kg/yr follows directly from the stored tritium mass and the 12.3-year decay constant.

Where 1.97 kg/yr comes from

The helium-3 production rate is a decay calculation, not a fusion calculation. If a tritium inventory of mass M is held, helium-3 grows at approximately λM per year, where λ = ln2 / 12.3 yr ≈ 0.0563 per year, and the mass-3 daughter carries essentially the same atom count. Over a year this is about 5.47% of the tritium mass converting to helium-3.

Under the reference tritium inventory and holding assumptions consistent with the ~4 kg/yr class breeding target, the resulting coproduct rate is near 1.97 kg/yr. The figure is deliberately quoted to three figures because it is a computed consequence of the inventory model, but it is only as firm as that model and the breeding it assumes.

Sensitivities

• Higher standing tritium inventory → more He-3 per year
• Shorter tritium residence (shipped/burned sooner) → less He-3
• Extraction cadence and getter efficiency set recoverable fraction
• Any shortfall in net TBR reduces both tritium and He-3 together

Honest framing

1.97 kg/yr is a design-and-simulation estimate contingent on the tritium program meeting its targets. It is a coproduct: Hyperion is optimized to breed tritium, and helium-3 is the yield of holding that tritium over time.

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.