A Glossary of Validation Terms

Plain definitions of the validation and open-science terms used across the breeder record, so a reader is never guessing what a word means.

Words used precisely

The breeder (Hyperion) record uses several terms in specific technical senses. This glossary fixes them so the pages read the same way to everyone.

• Verification: confirming the code solves its equations correctly (no machine needed).
• Validation: confirming the equations describe the real machine (needs hardware).
• Reproducibility: a third party obtaining the same output from the same inputs and code.
• Tier-1 reproduction: a byte-exact match in the reference environment.
• Tier-2 reproduction: a within-tolerance match across environments.
• TBR (tritium breeding ratio): tritium bred per tritium burned; local vs net distinguished.
• Local TBR: idealized breeding for full-coverage blanket; optimistic.
• Net TBR: breeding after real coverage, penetrations, and losses.
• Pre-registration: publishing a prediction and its falsifier before the data exists.
• Falsifier: the observation that would prove a prediction wrong.
• UQ (uncertainty quantification): propagating input uncertainty to output intervals.
• Sensitivity: how strongly an output responds to a given input.
• Honest gate: a named open question the record has not closed.
• FOAK / NOAK / BOAK: first-, next-, and best-of-a-kind machines in the build sequence.
• Full-power-year (fpy): one year of operation at full power, the unit for damage lifetimes.
• Concept DOI / version DOI: identifiers for the work in general vs a specific deposit.

Why a glossary is a validation tool

Ambiguous language hides disagreement. When 'reproduced' or 'validated' means one thing to the author and another to the reader, a claim can seem stronger than it is. Fixing the definitions is part of keeping the record honest. The distinctions that carry the most weight are verification versus validation and local versus net TBR: in each pair the two terms sound interchangeable and are not, and most over-claims in fusion communication come from sliding between them. The record uses the stricter member of each pair as its default.

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.