Oklo wins DOE startup authorization for Groves — clearing the way for fuel loading and first criticality

The US Department of Energy granted Oklo startup authorization for its Groves Isotope Test Reactor, following approval of the reactor's final safety analysis. The authorization lets Oklo load nuclear fuel, conduct startup testing and proceed toward first criticality — the point at which a self-sustaining fission chain reaction begins — which Oklo is targeting this month. Groves is advancing through the DOE-authorization route of the federal Reactor Pilot Program, launched to construct, operate and reach criticality on advanced test reactors at sites outside the national laboratories.

Why it matters

This is the regulatory gate the whole "AI needs firm power" nuclear narrative has been waiting to see cleared by an actual startup. The Reactor Pilot Program's DOE-authorization pathway was meant to be faster than the NRC's traditional licensing — the same bottleneck the NRC's own overhaul is trying to widen — and Oklo just became a live test of whether it delivers. Fuel loading is the concrete step that separates a design from a machine; a company whose stock has swung on "results, not hype" now has a dated path to the field's most legible proof point. The distinction to hold onto: this is authorization to start, not criticality itself — the physics milestone is still ahead.

What to watch

First criticality itself (the milestone that would move this from regulatory progress to a demonstrated reactor), the fuel-loading timeline, and whether other Pilot Program reactors clear the same DOE gate behind Oklo.