Oklo achieves first criticality less than a year after groundbreaking through the U.S. Department of Energy’s Reactor Pilot Program.
The Groves low-power test reactor is the first reactor under the program to achieve criticality on private land, built from the ground up on a greenfield site.
The Groves facility establishes the operational foundation for future commercial isotope production.
The project proves American nuclear deployment timelines can be measured in months rather than years.

Oklo Inc. (NYSE:OKLO) ("Oklo" or "the Company"), an advanced nuclear technology company, today announced that its Groves Isotope Test Reactor has achieved first criticality after achieving a controlled, self-sustaining nuclear chain reaction at low power. The milestone comes less than a year after groundbreaking and follows U.S. Department of Energy (DOE) authorization through the DOE Reactor Pilot Program (RPP).

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Groves Isotope Test Reactor facility (Image: Groves)

"Reaching criticality in less than a year is an incredible milestone for our team," said Oklo co-founder and CEO Jacob DeWitte. "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. Taken together, we believe these accomplishments establish a new benchmark for the Reactor Pilot Program and set the stage for the future of advanced nuclear deployment at scale."

The DOE’s RPP created a pathway that allowed engineering, construction, commissioning, and operational preparation to advance alongside DOE’s safety review and authorization. Groves demonstrates that the domestic nuclear industry can once again move from design through construction, authorization, and startup on timelines that are measured in months rather than years when developers, suppliers, and regulators work together on an integrated deployment approach.

"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. We applaud the work of the Oklo, DOE, and Idaho National Laboratory staff who helped achieve this milestone," said Assistant Secretary for Nuclear Energy Ted Garrish.

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, qualification work, and deployment execution that can inform future isotope production facilities.

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

"Texas is leading America’s nuclear renaissance by advancing the technologies that will power innovation and strengthen our nation's future," said Governor Abbott. "From expanding our nuclear workforce to rebuilding critical domestic supply chains, Texas is creating the foundation for the next generation of advanced nuclear development. Congratulations to Oklo on reaching this important milestone, which will help expand isotope production for critical medical therapies and reinforce Texas' leadership in nuclear innovation."

About Oklo Inc.: Oklo Inc. is developing fast fission power plants to deliver clean, reliable, affordable energy at global scale; establishing a domestic supply chain for critical isotopes; and advancing nuclear fuel recycling to convert used nuclear fuel into clean energy. Oklo was the first to receive a site use permit from the U.S. Department of Energy for a commercial advanced fission plant, was awarded fuel from Idaho National Laboratory, and submitted the first custom combined license application for an advanced reactor to the U.S. Nuclear Regulatory Commission. Oklo is also developing advanced fuel recycling technologies in collaboration with the U.S. Department of Energy and U.S. National Laboratories.

Forward-Looking Statements

This press release includes statements that express Oklo’s opinions, expectations, objectives, beliefs, plans, intentions, strategies, assumptions, forecasts or projections regarding future events or future results and therefore are, or may be deemed to be, "forward-looking statements." The words "may," "will," "could," "should," "expects," "anticipates," "intends," "plans," "believes," "seeks," "estimates," "continue," "might," "possible," "potential," "predict," "project," "goal," "would," "commit," or, in each case, their negative or other variations or comparable terminology, and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. These forward-looking statements include all matters that are not historical facts. They appear in a number of places throughout this press release and include statements regarding our intentions, beliefs or current expectations concerning, among other things, results of operations, financial condition, liquidity, prospects, growth, strategies and the markets in which Oklo operates. Such forward-looking statements are based on information available as of the date of this press release, and current expectations, forecasts and assumptions, and involve a number of judgments, risks and uncertainties.

As a result of a number of known and unknown risks and uncertainties, the actual results or performance of Oklo may be materially different from those expressed or implied by these forward-looking statements. The following important risk factors could affect Oklo’s future results and cause those results or other outcomes to differ materially from those expressed or implied in the forward-looking statements: risks related to the development and deployment of Oklo’s powerhouses, fuel fabrication and fuel recycling facilities, and radioisotope production activities; the risk that Oklo is pursuing an emerging market with no commercial project operating and regulatory uncertainties; risks related to acquisitions, divestitures, or joint ventures we may engage in; the need for financing to construct plants, which remain subject to market, financial, political, and legal conditions; risks related to an inability to raise additional capital to support our business and sustain our growth on favorable terms; the effects of competition; risks related to accessing high-assay low-enriched uranium, plutonium, and other fuels (including recycled fuels) at acceptable costs and under acceptable timelines; risks related to our supply chain; risks related to power purchase agreements; risks related to human capital; risks related to our intellectual property; risks related to cybersecurity and data privacy; changes in applicable laws or regulations, including tariffs; the outcome of any government and regulatory proceedings and investigations and inquiries; and the other factors set forth in our documents we have filed with the U.S. Securities and Exchange Commission (the "SEC").

The foregoing list of factors is not exhaustive. You should carefully consider the foregoing factors and the other risks and uncertainties of the other documents filed by Oklo from time to time with the SEC. The forward-looking statements contained in this press release are based on current expectations and beliefs concerning future developments and their potential effects on Oklo. There can be no assurance that future developments affecting Oklo will be those that Oklo has anticipated. Oklo undertakes no obligation to update or revise any forward-looking statements to reflect events or circumstances after the date of this presentation, except as may be required by law.

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Media and Communications for Oklo:

Bonita Chester, Head of Communications and Media at media@oklo.com

Investor Contact:

Sam Doane, Senior Director of Investor Relations at investors@oklo.com