Oklo achieves criticality in under a year, shares jump 5%

Oklo's Groves test reactor reached criticality in under a year, proving US nuclear deployment timelines can be measured in months rather than years. OKLO shares rose nearly 5% in pre-market trading.

"Reaching criticality in less than a year is an incredible milestone for our team," Jacob DeWitte, co-founder and CEO of Oklo, said. "Oklo developed Groves from a greenfield site on private land, completed full-scale civil excavation and construction, manufactured or commercially procured all components, including fuel, and developed its operating programs in-house."

The Groves facility, located in rural Caldwell County south of Austin, Texas, is a low-power test reactor that will serve as the operational foundation for Oklo's isotope production business. The company sourced low-enriched uranium from French fuel vendor Framatome. Oklo is the fifth of 10 companies in the DOE's Reactor Pilot Program to achieve criticality in the past two months, but the first to do so on private land at a greenfield site. The NRC granted Oklo its first license to operate a medical isotope reactor in March.

The milestone could accelerate Oklo's path toward commercial operations. The company is preparing a site near Idaho National Laboratory for its first 75-megawatt liquid-sodium-cooled power reactor, though it has not yet received permission to begin construction. Oklo's valuation reached nearly $24 billion at its peak since its 2024 public debut, and the company is also developing fuel recycling and domestic isotope production capabilities.

Groves Sets a New Deployment Benchmark

The DOE's Reactor Pilot Program created a pathway that allowed engineering, construction, commissioning, and operational preparation to advance alongside the agency's safety review and authorization. This integrated approach enabled Oklo to move from design through construction, authorization, and startup in months rather than years — a timeline that historically stretched a decade or more for conventional nuclear projects.

"Thanks to President Trump's precedent-setting directive to create the Reactor Pilot Program, Oklo's Groves Isotope Test Reactor is part of the revival of America's nuclear energy industry," said Ted Garrish, Assistant Secretary for Nuclear Energy.

Texas Gov. Greg Abbott said the project would help expand isotope production for critical medical therapies and reinforce Texas' leadership in nuclear innovation. The state has been actively courting advanced nuclear development, from expanding its nuclear workforce to rebuilding domestic supply chains.

Isotope Production and the Path to Commercial Reactors

Groves is part of Oklo Isotopes' broader effort to build domestic isotope production capabilities for healthcare, industry, research, space, and national security applications. The project has generated practical experience in project engineering, construction, procurement, reactor operations, startup procedures, safety readiness, training, and deployment execution.

The Groves project also established engineering practices, operating procedures, training programs, and commissioning experience that will reduce uncertainty and execution risk across every Oklo facility, including future isotope, powerhouse, and fuel cycle deployments.

Only two advanced nuclear startups — TerraPower and Kairos Power — are actively building reactors in the United States. Oklo is preparing a site near Idaho National Laboratory for its first small modular reactor but does not yet have permission to work on the reactor itself. The company's 2022 NRC license application was rejected, and it has yet to resubmit paperwork for its proprietary 75-megawatt liquid-sodium-cooled power reactors.

OKLO shares rose nearly 5% in pre-market trading following the announcement. The company's valuation has fluctuated significantly since its public debut, reaching nearly $24 billion at its peak. The Groves milestone gives Oklo a working reactor to validate its operational procedures and supply chain ahead of larger deployments, a critical de-risking step for a company whose commercial power plants remain years from operation.

This article is for informational purposes only and does not constitute investment advice.