The US Department of Energy announced on May 26 that it selected five nuclear energy startups to enter advanced negotiations to use surplus Cold War-era plutonium as fuel for advanced reactors [1, 2, 3, 4]. The selected companies are Oklo, Exodys Energy, SHINE Technologies, Standard Nuclear, and Flibe Energy [1, 2, 3, 4].
The plutonium comes from dismantled nuclear warheads, totaling about 20 metric tons stored at guarded US weapons facilities, where it must be handled with protective gear due to its 24,000-year half-life [1, 2, 3, 4]. Oklo plans to develop fuel in partnership with European company newcleo, which aims to build MOX fuel fabrication facilities [1, 2, 3, 4].
Jacob DeWitte, Oklo cofounder and CEO, said, "This program creates a pathway to use existing surplus material as bridge fuel for advanced reactors to bring more reactors online sooner" [1].
The program faces criticism from several Democrats who raised concern that using plutonium as reactor fuel could pose weapons proliferation risks and affect US defense posture [1]. Some experts share these concerns. Scott Roecker, Vice President of the Nuclear Threat Initiative, warned, "Countries have tried this before, and they concluded that, as nice as it would be to use that plutonium as fuel, it’s really just a liability and we need to dispose of it permanently" [2].
The US had previously halted plutonium fuel fabrication projects due to cost overruns and delays [2, 3]. The current selection follows a May 2025 order from former President Trump to halt plutonium disposal and pivot to fuel use in advanced reactors [1]. Energy Secretary Chris Wright, who had served on Oklo’s board but resigned and divested shares before joining the administration, oversees the program [2, 3, 4]. Sam Altman resigned as Oklo’s board chair last year [2, 3].
Negotiations will now proceed between the Department of Energy and the five companies to finalize plans for using the Cold War-era plutonium as nuclear fuel.
