Oklo reached a key milestone last week. On August 6 its Groves Isotope Test Reactor achieved criticality at 9:19 p.m. EDT. The event happened at a greenfield site in Lockhart, Texas. And it happened fast. The company built the entire facility in less than a year.
This 15-megawatt thermal pool-type, water-cooled, nonpressurized unit now produces a steady chain reaction. It marks the fifth advanced reactor to hit this point under the Department of Energy’s Reactor Pilot Program. Previous successes came from Antares Nuclear, Valar Atomics, Deployable Energy and Aalo Atomics. But Groves stands apart. It is the first built on private land rather than at a national laboratory.
“Reaching criticality in less than a year is an incredible milestone for our team,” said Jacob DeWitte, Oklo co-founder and CEO. He pointed to the in-house work. Oklo handled site selection, civil excavation, component manufacturing or procurement including fuel, and operating programs. “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 Department of Energy celebrated the news. Assistant Secretary Ted Garrish thanked Oklo, DOE and Idaho National Laboratory staff. He tied the success to regulatory reforms and President Trump’s energy dominance agenda. The pilot program itself stems from an executive order aiming to get test reactors running quickly. Three or more were supposed to operate by a July 2026 deadline. Oklo and its peers beat expectations.
Texas Governor Greg Abbott added his voice. “From expanding our nuclear workforce to rebuilding critical domestic supply chains, Texas is creating the foundation for the next generation of advanced nuclear development,” he said. The reactor will test technologies for isotope production. Those isotopes support medical therapies, advanced manufacturing, scientific research, space exploration and national security.
Oklo itself traces its name to a natural nuclear reactor in Gabon two billion years ago. The company, backed by OpenAI CEO Sam Altman, went public through a SPAC in 2024. Its stock has drawn retail investors betting on an atomic renaissance driven by data-center power demand. Yet the path remains bumpy. In 2022 the Nuclear Regulatory Commission rejected Oklo’s initial license application for a power reactor. Regulators cited gaps in the application. The company later secured a license for medical isotope work in March 2025, according to reporting by Canary Media.
The Groves reactor used commercial fuel from Framatome. Experiences here will shape Oklo’s larger ambitions. The firm plans a 75-megawatt electric Aurora Powerhouse. That design is a liquid-metal-cooled fast reactor using metallic fuel. It can run on recycled nuclear waste. Oklo has also talked about a plutonium-fueled Pluto variant. Commercial deployment targets the late 2020s. The company is preparing a site near Idaho National Laboratory for its first Aurora unit. Construction permission there has not yet arrived.
Broader industry momentum helps. The DOE selected 11 projects last year for accelerated test reactors. Oklo joined a Trump administration program announced in July to speed nuclear power for artificial intelligence data centers. The effort includes Microsoft, Nvidia and X-Energy. It carries roughly $200 million in support. Tech giants face soaring electricity needs. Traditional grids strain under the load. Small modular reactors promise factory-built units, lower upfront capital and flexible siting near data centers.
Yet challenges persist. Supply chains for advanced fuels remain thin. High-assay low-enriched uranium is preferred for compact designs and longer cycles. Oklo secured some from the DOE for its first commercial reactor. It also plans a fuel recycling facility in Oak Ridge, Tennessee, with production eyed for the early 2030s. Partnerships with Centrus and others aim to expand domestic capacity. Reuters has tracked these supply-chain efforts closely in recent months.
Oklo’s order book shows interest. The company holds nonbinding indications for more than 50 reactors totaling over 700 megawatts electric. Deals include the Southern Ohio Diversification Initiative at a former DOE site. Meta Platforms signed agreements to develop projects with Oklo, potentially reaching 1.2 gigawatts in Ohio by 2030. Those pacts, reported by Reuters in January, sent Oklo shares surging nearly 20 percent at the time.
Investors have other ways to play the theme. The VanEck Uranium and Nuclear ETF holds about 4.4 percent in Oklo. Its top positions include Constellation Energy, Cameco and Public Service Enterprise Group. The Global X Uranium ETF carries roughly 6.2 percent Oklo alongside heavier bets on Cameco and uranium trusts. Both funds have posted strong five-year returns, though recent performance has been mixed. The Motley Fool highlighted these vehicles in its coverage of the criticality announcement.
Success at Groves proves private capital can move at speed. “By all accounts and measures, this is the fastest-built, privately sited, privately funded, privately built nuclear reactor in world history,” Oklo posted on X. The claim holds weight when measured against historical nuclear timelines. Traditional plants often take a decade or longer. Modular approaches and streamlined regulation cut that dramatically here.
But one test reactor does not equal commercial scale. Oklo still must license the Aurora design fully. Fuel qualification, supply reliability and public acceptance matter. Opposition to nuclear projects has delayed projects before. Waste handling, even with recycling claims, invites scrutiny. And costs. Early SMR estimates have risen across the sector. Delivery on time and on budget will decide whether this moment becomes a turning point or another false start.
The timing aligns with national priorities. Electricity demand forecasts keep climbing. Data centers alone could add hundreds of terawatt-hours by 2030. Nuclear offers firm, carbon-free baseload. Natural gas fills gaps today but faces its own constraints. Renewables scale quickly yet require storage and transmission upgrades that lag. Advanced reactors could bridge those gaps if regulators and markets cooperate.
Oklo’s team sees the Groves result as proof of concept. They built everything from scratch on private land. No federal site bureaucracy slowed initial steps. That model could apply elsewhere. Other pilot participants may follow similar paths. The DOE calls the summer’s five criticalities a sign of America’s nuclear comeback. Whether that translates into dozens of operating plants in the 2030s depends on execution in the next few years.
For now the atom split in Texas stands as tangible progress. A small reactor went from dirt to chain reaction in months. Industry insiders will watch the data from Groves closely. It will inform isotope production plans and, eventually, power plant designs. Oklo has momentum. The question is whether the company and its peers can sustain it through licensing, construction and operation at full commercial scale. The stakes are high. Power-hungry AI and a push for energy independence hang in the balance.