Oklo took its Groves-1 test reactor near Lockhart, Texas, from bare ground to a chain reaction in under a year, and on Nov. 12 the last gate on the way to routine running was reported open. The Department of Energy cleared the final operations hold point for the reactor, moving it into a research, testing and training phase. The sources give no date for the sign-off itself.
Read next on Morning Overview: A handful of car transmissions are so tough that mechanics say they almost never die
No Nuclear Regulatory Commission license is involved in this step. DOE authorizes research reactors on its own authority.
The final operations hold point and what DOE cleared
World Nuclear News reported that DOE cleared the final operations hold point for the Groves Isotope Test Reactor, which the outlet described as cleared for unrestricted operations. That characterization is the outlet’s; the reachable material does not carry DOE’s own text of the clearance, so this article reports the hold point as the fact and the wording as World Nuclear News’s. The reactor sits in Caldwell County and is built on private land.
Earlier gates were public. NEI Magazine said DOE approved the reactor’s Documented Safety Analysis earlier in July, and Oklo’s July 23 announcement said DOE granted startup authorization, which finished the department’s authorization review and allowed fuel loading, startup testing and operations after a readiness review of Oklo’s engineering, organization and operations. Mike Goff, DOE’s principal deputy assistant secretary for nuclear energy, said in that release that Oklo had been able to accelerate its progress and was ready for the next step. A NEI Magazine report from July 28 carried the same statements.
The legal footing is the Atomic Energy Act, under which DOE can authorize reactors for research, development and demonstration, while the Nuclear Regulatory Commission reviews and approves commercial reactor designs. Groves-1 therefore answers to the department, and each hold point it passes is a DOE decision. The pilot program was built around exactly that pathway, a faster federal route to build and run a test reactor before any commercial license is sought.
One of 11 pilot reactors racing a July 4 target
Groves is one of 11 projects DOE picked in August 2025 for its Nuclear Reactor Pilot Program, which grew out of a May 23, 2025 executive order. The program’s goal was criticality for at least three advanced reactor concepts outside the national laboratories by July 4, 2026. World Nuclear News reported on Aug. 6 that Groves reached first criticality, and noted that other pilot reactors, among them Antares Mark-0, Valar Ward 250, Deployable Energy’s Unity and Aalo’s Critical Test Reactor, reached criticality in June and July, per its milestones roundup.
The reactor is described only as low-power. The reachable reports do not state its thermal output, its fuel or whether it is a TRIGA design, so none of those are asserted here.
Oklo’s own account of the build is that it completed full-scale civil construction, obtained or manufactured every component including the fuel, and developed its operating programs in-house, all on a greenfield site. Chief executive Jacob DeWitte called reaching criticality in less than a year an incredible milestone for his team, called the facility the fastest he knew of to go from greenfield to substantial completion, and said the experience carries over fully to future commercial deployments. The executive order behind the pilot program, signed in May 2025, set the target of criticality for at least three test reactors through DOE’s authorization process by July 4, 2026.
Training, control-rod tests and isotope benchmarking
Oklo plans to use Groves-1 to train and qualify nuclear personnel, to test the performance and reliability of control rod drive mechanisms, and to run criticality and reactivity benchmarking for isotope production and engineering models. The data may also help improve fuel performance and power output in light water reactors, according to World Nuclear News.
The reactor is also a rehearsal. Operating experience will inform Groves-2 Forge, Oklo’s planned isotope production and processing pilot facility under DOE’s Nuclear Energy Launch Pad initiative, and Groves-1 will test capabilities relevant to the company’s Aurora powerhouse, a fast fission reactor. DeWitte said taking the project from greenfield to criticality in less than a year was an important demonstration.
Chimi Zacot, DOE’s acting deputy assistant secretary for nuclear reactors, said successes like the criticality of Groves-1 are now paving the way for what comes next. One path is already open on paper: World Nuclear News notes that in October 2026 the Nuclear Regulatory Commission finalized a rule letting applicants use DOE or Department of War reactor demonstration data in commercial license applications.
Still unanswered is how quickly any of that data reaches a commercial application. Neither Oklo nor DOE has said, in the material reviewed, how long Groves-1 will run or when the Groves-2 Forge facility will break ground. The date of the final hold-point clearance, the reactor’s power level and its fuel are all absent from the public reports reviewed, and they are the figures that would let outside engineers compare Groves-1 with the other pilot reactors that reached criticality this summer.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
More from Morning Overview
- The Justice Department asked courts to undo approvals for three offshore wind farms, one already making power
- Over 20 trillion gallons of rain fell on the Four Corners states and Nevada in two weeks
- 11 engines built to run well past 200,000 miles
- Two Kentucky residents died when a small plane crashed at Missouri’s Lake of the Ozarks, and the NTSB is investigating
