The US Department of Energy has granted startup authorisation for the Oklo Groves reactor authorisation, clearing the advanced nuclear company to begin fuel loading and startup testing at its Groves Isotope Test Reactor in Lockhart, Caldwell County, Texas. The approval completes the DOE’s authorisation process under its Reactor Pilot Program and opens the path to first criticality.
From Groundbreaking to Oklo Groves Reactor Authorisation in Ten Months
Oklo went from groundbreaking to authorisation in a little over ten months, constructing the facility, training staff, establishing nuclear programmes and procedures, and procuring fuel and major equipment from commercial suppliers. Co-founder and chief executive Jacob DeWitte said it represented the fastest progression from greenfield to substantial completion for a full-scale, privately funded and privately sited reactor the company is aware of, and that the sector can ‘move at a pace that many did not believe possible’.
Before granting startup authorisation, a multidisciplinary DOE team conducted a readiness review examining whether facility procedures and personnel training were adequate, whether the facility and equipment conformed to the approved design, and whether safety equipment requirements were met, according to the Oklo newsroom.
The safety documentation process had already cleared two stages. DOE first approved Oklo’s Preliminary Documented Safety Analysis, then its full Documented Safety Analysis for the Groves Isotope Test Reactor, moving the project from the documentation phase into the department’s final pre-startup review. Oklo had been targeting first criticality for July 2026.
The DOE Programme Behind the Clearance
The DOE Reactor Pilot Program was announced in June 2025 and derives from President Trump’s Executive Order 14301, which reforms nuclear reactor testing at the Department of Energy. Its stated goal is to construct, operate, and achieve criticality in at least three test reactors using the DOE authorisation process by 4 July 2026.
The programme initially selected 11 advanced reactor projects, including Aalo Atomics, Antares Nuclear, Atomic Alchemy, Deep Fission, Last Energy, Oklo (two projects), Natura Resources, Radiant Industries, Terrestrial Energy, and Valar Atomics. World Nuclear News reported the Groves reactor is sited near Lockhart in Caldwell County, Texas.
Groves is a low-power test reactor built to validate Oklo’s reactor design, construction methods, and operating model before the company scales to commercial isotope production. Because it was privately financed, built on private land, and assembled with full-scale systems and commercially sourced components, Oklo says it has a repeatable template for future projects.
The reactor is designed to support domestic production of critical isotopes used in cancer treatment, manufacturing, scientific research, space exploration, and national security applications, reducing US reliance on overseas supply. Separately, the DOE also selected Oklo for its advanced nuclear fuel line pilot programme, alongside Terrestrial Energy, TRISO-X, and Valar Atomics, with the stated aim of strengthening domestic nuclear fuel supply chains and reducing dependence on foreign enriched uranium.
Balance Sheet Signals Early Commercial Activity
Oklo’s unaudited balance sheet as of 30 June 2026 disclosed contract assets of $2,402 thousand and contract liabilities of $53 thousand, both of which stood at zero as of 31 December 2025, according to the company’s 10-Q filed with the SEC. The emergence of contract balances in Q2 2026 points to early commercial arrangements being in place ahead of the reactor becoming operational.
OKLO shares have lost around 70% of their value from recent highs. The stock’s next test is whether fuel loading and startup testing proceed to first criticality on the schedule the company has outlined.
