Methodology

Who is on the board

An entrant is a company with a named new-design commercial power reactor of roughly 350 MWe or less per unit, and documented U.S. regulatory or physical progress toward deploying it: an NRC docket, an NRC-approved design, a DOE authorization, a sited project, or a binding U.S. customer. 18 companies qualify as of 2026-08-06. This is a tracked sample, not a census of everyone building a reactor.

Each entrant page states one specific qualifying fact and cites the single source that establishes it. Where a company has more than one claim to a place on the board, the others appear in its ledgers with their own sources rather than being bundled into the roster basis.

Companies that only run test reactors or make fuel appear as context on entrant pages, not as entrants. Large AP1000-class reactors stay in the stage pipeline as tracked context; they are not racing to a first gigawatt.

What counts as a megawatt

Only U.S. megawatts. A U.S. vendor building the same design abroad, at Darlington in Ontario or Doicești in Romania, has that progress shown on its page as design proof contributing zero megawatts to the U.S. race, because the site’s claim is about U.S. deployment.

Test reactors and critical experiments contribute zero megawatts to every band. A criticality proves the physics works. It is not electricity, and it is not a license to sell any. All four reactors that reached criticality before the July 4, 2026 federal goal were zero-power units, and all four contribute zero megawatts here.

A company-stated target never moves a megawatt between bands. Only a documented action does. Targets are printed beside the regulator-documented state so a claim never floats free, and where a target conflicts with another account, both are shown.

The six bands

Each megawatt sits in exactly one band, the strongest state its evidence supports, so the bands never double-count. Bands are never added across frames, and announced megawatts never affect the ranking.

A DOE authorization is not an NRC license

These are two different pathways and the board keeps them apart. The NRC licenses commercial power reactors; a construction permit authorizes building one, and a separate operating license is still required before it may run. DOE authorizes reactors on its own sites under its own safety process, which is how the pilot-program reactors were built and started so quickly.

A reactor being built under a DOE authorization is real physical progress, so it gets its own band rather than being folded into either NRC-permitted construction or a paper application. Oklo’s Aurora at Idaho National Laboratory is the case that forces the distinction: ground was broken in September 2025 under the DOE pathway while its NRC combined license is still under review. Ranking it beside an NRC-permitted build would overstate it; calling it an application would ignore a reactor being built.

Binding and non-binding never merge

A memorandum of understanding, a letter of intent, a master agreement, and a press-released target are announcements. They are recorded, dated, sourced, and kept on their own track, and the words “announced, non-binding” travel with the figure everywhere it appears.

This is the largest single fact on the board, and it is worth stating in both frames because they answer different questions. Against every megawatt resting on an executed action of any kind, including applications merely filed, announced capacity runs about 20 to one. Against the megawatts actually being built today, it runs about 91 to one.

The largest single announcement on record, Switch master power agreement at 12,000 MWe, is on its own roughly 27 times all the new-design capacity under construction in the United States. That is why the two are never summed into one number.