Oklo achieved criticality, in a test reactor that is not its power reactor

The Groves Isotope Test Reactor south of Austin went critical, built in under a year on private land. The commercial 75 MW design has no NRC application on file since 2022.

Oklo has achieved criticality — a sustained fission chain reaction — in its Groves Isotope Test Reactor, built on private land in rural Caldwell County, south of Austin, Texas, as part of a Department of Energy testing programme. The low-enriched uranium fuel came from the French supplier Framatome. Construction took less than a year.

Criticality is a real physical event and it is the reason this card scores as measured rather than as a company claim. The build time is the genuinely interesting number: under twelve months, on private land, under a DOE test authorisation. Conventional nuclear construction timelines are measured in decades, and a large part of that is regulatory sequencing rather than concrete. A demonstration that a reactor can be assembled in a year under a different authorisation path is a data point about the process, which is where most of nuclear's cost actually sits.

Now the distance still to travel, which is considerable and should not be softened. This is a low-power test reactor supporting Oklo's medical isotope business, not the Aurora power plant. The commercial design is a 75-megawatt liquid-sodium-cooled reactor, and Oklo has not resubmitted its Nuclear Regulatory Commission licence application since that application was rejected in 2022. The company is preparing a site near Idaho National Laboratory but does not yet have permission to work on the reactor itself. Criticality here is necessary and a long way from sufficient.

Source: Canary Media