Overview
- Oklo’s Groves Isotope Test Reactor reached first criticality on Wednesday, Aug. 5, 2026, meaning the facility achieved a controlled, self‑sustaining nuclear chain reaction at low power.
- The Groves site is a low‑power test reactor built to produce medical and research isotopes and to generate hands‑on operational data rather than to sell electricity.
- The Department of Energy’s Reactor Pilot Program granted startup authorization in late July 2026, enabling Oklo to load fuel and begin startup testing under concurrent federal readiness reviews.
- Oklo constructed Groves on private greenfield land using largely in‑house engineering and commercially procured fuel, and the company says it will use operating procedures and training from Groves at future projects.
- Investors reacted positively with share gains but Oklo remains pre‑revenue and faces separate multi‑year hurdles for its Aurora commercial reactors, including NRC licensing, HALEU fuel supply and project financing.