Nuclear startup Oklo splits its first atoms in test reactor

Oklo, a publicly traded small-modular-reactor firm backed by OpenAI chief Sam Altman, has become one of the highest-profile companies working on next-generation nuclear energy technologies. Two years ago it debuted on the stock market and became retail investors’ go-to for betting on America’s atomic renaissance.

Yet while the company’s valuation rose at one point to nearly $24 billion and its plans expanded into recycling nuclear waste, fabricating its own fuel, and producing medical isotopes, it had yet to split atoms from one of its reactors.

That is, until now. On Thursday morning, Oklo announced that its Groves Isotope Test Reactor, a low-power unit the company built on private land south of Austin, Texas, as part of a Department of Energy testing program, had sustained a chain reaction. The reactor is a demonstration version of the technology Oklo will use for its new medical isotope business, though the firm says it will help its efforts to build reactors that generate electricity.

Known as achieving criticality, this chain reaction is a necessary if far from sufficient step toward commercialization for nuclear-energy aspirants. Today’s announcement — first reported by Canary Media — makes Oklo the fifth of the 10 companies in the DOE’s Reactor Pilot Program to split atoms in the past two months. Construction on the Groves test reactor was completed in less than one year.

In 2022, Oklo’s application for a Nuclear Regulatory Commission license was resoundingly rejected. It has yet to resubmit the paperwork for its proprietary 75-megawatt liquid-sodium-cooled power reactors, though the agency granted Oklo its first license to operate a medical isotope reactor in March.

As it stands, just two advanced nuclear startups — TerraPower and Kairos — are actively building out reactors in the United States. Oklo is preparing a site near the Idaho National Laboratory for its first small modular reactor but does not yet have permission to work on the reactor itself.

The Groves facility, located in rural Caldwell County, allows the company to essentially practice for when and if it gets the greenlight to build its first full-scale reactor. The test reactor will also grease the links of the supply chain that Oklo will use both for its medical isotope business, which is intended to generate early revenue, and eventually for its reactors. For example, Oklo bought the low-enriched uranium for the test reactor from a commercial vendor, the French reactor-fuel company Framatome.

In contrast to the four other startups that have announced criticality this year, Oklo’s project was built at ​“a greenfield site on private land” in a process that included ​“full-scale civil excavation and construction, commercially procured fuel and all major components, and developed its operating programs in-house,” co-founder and CEO Jacob DeWitte said in a statement. All others happened at federal facilities or on public land.

“Reaching criticality in less than a year is an incredible milestone for our team,” DeWitte said.

In a statement, Texas Gov. Greg Abbott said the project would lay the groundwork for expanding ​“isotope production for critical medical therapies and reinforce Texas’ leadership in nuclear innovation.”

“Texas is leading America’s nuclear renaissance by advancing the technologies that will power innovation and strengthen our nation’s future,” said the Republican, who is running for reelection this year.