Oklo Inc.'s stock moved higher after the U.S. Department of Energy granted clearance for unrestricted operations at the company's Groves-1 test reactor, enabling the facility to advance into an expanded research, testing and training phase. Shares rose roughly 7% on the update.
Groves-1 reached first criticality at low power in August 2026, less than a year after the site was broken ground, under the DOE's Reactor Pilot Program. It was the first reactor on private land to achieve criticality within that program.
With the DOE authorization in place, Groves-1 is cleared to progress beyond initial startup tasks and begin wider experimentation. The facility will carry out testing of technologies that have relevance to future isotope-dedicated reactors as well as to Oklo’s Aurora line of fast fission reactors. In addition, operations at Groves-1 will support workforce training and qualification activities and allow equipment evaluations, including assessments of control rod drive mechanism performance.
The reactor will be used to generate criticality and reactivity benchmarking data intended to support Oklo’s isotope production capabilities and to validate the engineering and design models that underlie those plans. The testing and data collected may also have applicability to light water reactors, offering potential insights that could inform fuel performance and power output across both small and large reactor designs.
"Taking Groves-1 from greenfield to criticality in less than a year was an important demonstration of what our team can accomplish," said Oklo CEO and co-founder Jacob DeWitte. "Now we’re building on that experience by operating the reactor, testing new capabilities, and learning directly from the work."
Experience gathered at Groves-1 will also feed into Groves-2 Forge, Oklo’s planned isotope production and processing pilot facility that was chosen under the DOE’s Nuclear Energy Launch Pad initiative. Groves-2 Forge is being designed to integrate reactor irradiation with hot-cell processing, with an initial production focus on lutetium-177, a medical isotope used in targeted cancer treatments.
Investors and market participants have raised questions about how much of the DOE clearance was already reflected in Oklo’s share price, and observers are noting that other nuclear developers face their own DOE approval processes. The authorization at Groves-1, while a milestone for Oklo, also highlights the regulatory steps that remain relevant for peers within the sector.
Summary
The Department of Energy approved unrestricted operations for Oklo’s Groves-1 test reactor, allowing the facility to move into a broader research, testing and training phase after achieving first criticality at low power. The clearance supports testing aimed at isotope production, reactor engineering validation, workforce training and equipment performance evaluations, and will inform plans for the Groves-2 Forge pilot facility focused initially on lutetium-177.
Key points
- DOE authorization permits Groves-1 to begin expanded research, testing and training activities - impacting the nuclear energy development sector and related capital markets.
- Data from Groves-1 will be used for isotope production benchmarking and to validate engineering models, with potential relevance to light water reactors - relevant to both energy and industrial engineering stakeholders.
- Findings and operating experience will inform Groves-2 Forge, Oklo’s planned isotope production and processing pilot facility focused initially on lutetium-177 - linking the project to the medical isotope supply chain.
Risks and uncertainties
- Market pricing uncertainty - it is unclear how much of the DOE clearance had already been priced into Oklo’s stock ahead of the announcement, which could affect near-term share volatility.
- Regulatory and approval hurdles for peers - other companies in the nuclear sector may still face similar DOE approval steps, creating uneven progress across the industry.
- Technical and validation uncertainty - equipment testing and benchmarking at Groves-1, including control rod drive mechanism evaluations, will determine whether engineering models and isotope production plans are fully validated.