The Sensitivity Analysis

The breeder record identifies which inputs the headline results are most sensitive to, so scrutiny and future measurement focus where they matter.

Not all inputs matter equally

Uncertainty quantification tells you how wide an output is; sensitivity analysis tells you why. The breeder (Hyperion) record ranks inputs by how strongly they move the headline results, so a reviewer knows which assumptions are load-bearing and which are cosmetic.

What the ranking is used for

• Prioritizing FOAK diagnostics toward the highest-impact quantities.
• Focusing benchmarking effort on the models that matter most.
• Making the open gates legible: the TBR gate is a high-sensitivity item, which is why it is flagged.
• Guarding against false precision on quantities that barely move the answer.

Coupling matters

Sensitivities are not independent. Confinement, density, and beta interact, so the analysis examines joint variations, not one-at-a-time perturbations alone. This is how the record avoids a design that satisfies each limit separately while failing a coupled constraint — a failure mode described in the density benchmark.

The ranking is also revisited as the models mature: an input that looks minor today can rise if a coupled interaction is discovered, so the sensitivity analysis is regenerated with the rest of the record rather than fixed once. The current ordering is a snapshot, and the top items — confinement and net blanket coverage — are exactly the two the honest gates already flag.

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.