Oklo's Test Reactor Went Critical in Under a Year. Its Actual Power Plant Is Still Two Years Out

Oklo's Groves Isotope Test Reactor in Texas achieved first criticality on August 5, 2026, about 11 months after construction began on a greenfield private site. Criticality is the point at which a nuclear chain reaction becomes self-sustaining — the fundamental threshold every reactor must cross before it can operate. Oklo co-founder and CEO Jacob DeWitte called reaching that point in under a year "an incredible milestone for our team," noting the company handled the civil excavation, construction, component manufacturing and procurement, and operating-program development itself.

Oklo describes Groves as the fastest transition from greenfield to criticality for a full-scale, privately funded and privately sited reactor in history, and the first project under the Department of Energy's Reactor Pilot Program — a framework created under a Trump administration directive that lets construction and DOE safety review proceed concurrently — to reach criticality on private land. It's worth being precise about what Groves actually is: an isotope-production test reactor aimed at supplying healthcare, industrial, research, space, and national-security customers, not a power plant, and a business Oklo has described as potentially high-margin. It is a separate project from Oklo's commercial Aurora power facilities.

Those commercial projects remain years out. Aurora-INL, the power facility planned at Idaho National Laboratory, is still targeted for 2028; Aurora-Ohio, which is planned to support Meta's data centers, is targeted for early 2030. Reaching criticality at a test reactor demonstrates real execution capability — Oklo hit its own aggressive construction timeline — but it does not shorten the runway to commercial electricity revenue, which is still governed by separate, larger regulatory and construction milestones at the Aurora sites.

The milestone landed alongside Oklo's Q2 2026 update. The company reported $3.0 billion in cash and marketable securities after raising $1.9 billion through at-the-market equity offerings in the first half of 2026, pushing total stockholders' equity to $3.3 billion from $1.5 billion at year-end 2025. Against that liquidity, Oklo posted a year-to-date net loss of $81.6 million and raised its full-year operating cash use guidance to $120 million to $150 million, with capital expenditures projected at $400 million to $500 million — the financial profile of a company still years from revenue, funding an aggressive construction pace with equity. OKLO shares rose as much as 7.63% to $45.41 following the presentation, still well below the stock's 52-week high of $193.84, as the market weighed a genuine, well-executed technical milestone against a commercial timeline that hasn't moved any closer.