The Center-Post Lifetime Gate
A compact spherical tokamak puts its center stack in the harshest neutron field; the breeder record carries a limited-lifetime note (order 0.01 full-power-years) as a stated engineering constraint.
The price of being compact
The spherical geometry that gives the breeder (Hyperion) its high-beta, high-bootstrap advantages also forces the center stack into a small radius, close to the plasma, in an intense 14 MeV neutron flux. Neutron damage accumulates in the center-post conductor and structure, and that sets a replacement interval. The record states this as an engineering gate, not a solved problem.
The lifetime note
For the most exposed center-stack element, the record carries a limited-lifetime note on the order of 0.01 full-power-years. That figure is a design-and-simulation estimate of accumulated damage, and it drives the machine toward planned center-post replacement as a routine maintenance operation rather than a catastrophic failure mode.
Design responses, honestly bounded
- Shielding budget between plasma and center stack, traded against compactness.
- A center stack engineered for scheduled replacement, not permanence.
- Material choices evaluated for neutron tolerance.
- The lifetime treated as a quantity to measure at FOAK, since damage models carry real uncertainty.
The honest reading: compactness is a deliberate trade, and its cost is a center stack with a finite, uncertain life that the machine must be designed to swap. See what FOAK will test.
This page describes a design-and-simulation study, not a built machine. Construction of the breeder (Hyperion) begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. No hardware net-gain claim is made before FOAK.