Why We Build the Breeder First

Kronos builds the breeder (Hyperion) before the burner because a compact D-T machine reaches useful output on fusion gain alone.

The sequencing decision

Kronos develops two machines: a breeder (Hyperion), a compact D-T spherical tokamak, and a burner (Aegis / MetroVolt), a D-3He tandem-mirror generator. The breeder is built first. The reason is a difference in what each machine must demonstrate before it delivers value.

The breeder is an isotope and neutron foundry. Its product is material: a tritium class output near 4 kg/yr, a helium-3 coproduct near 1.97 kg/yr, and 14 MeV neutrons for irradiation services. To deliver those products the machine needs fusion gain, not net electrical output. A device with Q_sci of 3.076 producing 85.0 MW of fusion power generates the neutron flux that drives breeding and activation. That flux is the product.

Gain-only is a lower bar than net electric

Net electricity requires that recirculating power for magnets, heating, cryogenics, and balance-of-plant be smaller than gross electrical output. That is a harder threshold than scientific gain. The burner is designed toward net electric output via direct energy conversion, and its economics only close at fleet scale. Building it first would mean waiting on the harder demonstration before any value is delivered.

Foundry logic

The breeder is sized to a supply requirement, not to a megawatt target. It is deliberately compact. That keeps the first build tractable, retires physics and engineering risk on the smaller machine, and produces a marketable output stream from the neutron economy while the burner physics continue to mature. The breeder also supplies the tritium and, over time, the helium-3 that the D-3He burner will eventually consume.

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.