The Fusion-Relevant Irradiation Spectrum

Only a D–T source produces the 14 MeV-peaked spectrum that governs fusion materials behavior; Hyperion supplies it in usable quantity.

Spectrum is the whole point

Irradiation testing is only as relevant as the neutron energy spectrum it uses. Two facilities can deliver the same total flux yet cause entirely different damage if their spectra differ, because reaction cross-sections and damage physics are energy-dependent. For qualifying fusion materials, the spectrum must resemble that of a D–T plant.

How the sources compare

• Fission reactors: spectrum peaks near 1–2 MeV; no 14 MeV component; wrong He/dpa
• Spallation sources: broad high-energy tail, but different reaction mix and limited volume
• Accelerator D–Li sources (e.g., IFMIF-class): fusion-like but not a burning plasma, limited volume
• D–T fusion (Hyperion): genuine 14.1 MeV birth spectrum in bulk

The distinctive feature of the fusion spectrum is the sharp 14.1 MeV peak, which opens the threshold reactions responsible for helium and hydrogen generation. Softening or omitting that peak, as fission testing does, systematically misrepresents how a material will behave in a fusion plant.

Why in-machine testing is valuable

Placing test articles inside a running D–T machine exposes them to the actual plant spectrum, including its spatial and temporal variation, rather than an approximation. Combined with controlled temperature and instrumented fluence, this yields qualification-grade data. Hyperion's ability to offer this at 85.0 MW is a design-and-simulation capability, validated once the machine operates at FOAK.

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.