Oklo's Groves Isotope Test Reactor reached criticality the evening of August 5 at the company's facility in Lockhart, Texas, becoming the fifth reactor authorized by the Department of Energy to reach the milestone this year. The announcement came from Oklo Isotopes, a subsidiary Oklo formed after acquiring radioisotope production company Atomic Alchemy in 2025.
Oklo cofounder and CEO Jacob DeWitte called reaching criticality in under a year an important milestone, noting the company built Groves from a greenfield site on private land, handling civil construction, component procurement, and fuel manufacturing largely in-house.
The milestone follows a goal set under Executive Order 14301, which directed the Department of Energy to establish a Reactor Pilot Program aimed at getting at least three privately developed test reactors to criticality by July 4. Antares and Valar Atomics reached criticality in June, Deployable Energy followed in early July, and Aalo Atomics achieved the milestone on July 4 itself.
The 15-megawatt-thermal, water-cooled Groves reactor is designed to support future isotope production for health care, industrial, and research applications. Texas Governor Greg Abbott welcomed the news, citing the state's growing nuclear workforce and supply chain. Oklo has two additional reactor projects underway: the 75-megawatt Aurora Powerhouse and the Pluto reactor.
Source: American Nuclear Society / Nuclear Newswire - https://www.ans.org/news/2026-08-06/article-8277/oklos-isotope-test-reactor-achieves-criticality/