Oklo’s Groves Isotope Test Reactor successfully achieved criticality, becoming the fifth DOE-authorized reactor to go critical this summer.
August 6, 2026
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WASHINGTON — Last night, as part of the U.S. Department of Energy (DOE) Reactor Pilot Program, Oklo’s Groves Isotope Test Reactor successfully achieved criticality. The experiment took place at the company’s facility in Lockhart, Texas. Groves is the fifth DOE-authorized advanced reactor to achieve criticality this summer, further solidifying America’s nuclear comeback.
"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.
Oklo’s test reactor will inform the development of a future commercial variant designed to produce isotopes for medicine, advanced manufacturing, scientific research, space exploration, and national security needs.
“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.”
Oklo joins Antares Nuclear, Valar Atomics, Deployable Energy and Aalo Atomics in a growing group of nuclear reactor developers who, under DOE authorization, were able to rapidly move from design to demonstration with first-of-a-kind nuclear technologies. With DOE oversight and technical support, these companies have collectively reset the nuclear industry’s expectations on the timeline for the development and deployment of advanced reactors.
DOE’s new authorization pathway models how regulatory reform can accelerate innovation and help usher in a golden age for the nuclear energy industry and advancement of President Trump’s Energy Dominance agenda.
Learn more about the Reactor Pilot Program and the next evolution of DOE-authorized demonstration projects under the Nuclear Energy Launch Pad.