The United States government has selected five companies for advanced discussions on a plan to use Cold War-era plutonium as fuel for nuclear reactors. The announcement was made by the US Department of Energy on Tuesday. The move is part of a broader effort by the Donald Trump administration to reuse surplus plutonium from dismantled nuclear warheads instead of disposing of it.

The plutonium is currently stored at heavily protected weapons facilities in states such as South Carolina, Texas and New Mexico. The material has a half-life of nearly 24,000 years and requires special handling and protective equipment because of its radioactive nature. According to reports by Reuters last year, the Trump administration plans to make nearly 20 metric tonnes of plutonium available to private power companies for use in advanced nuclear technologies.

Among the companies chosen for the next stage of discussions is nuclear energy company Oklo. Following the announcement, Oklo’s stock rose by more than 5.5 per cent and reached $69.51 per share. The company said it plans to work with European nuclear technology firm Newcleo to develop the fuel. Newcleo is focused on building advanced high-tech nuclear reactors and is expected to contribute fuel expertise and possible investment support for the project.

The other selected companies include Exodys Energy, SHINE Technologies, Standard Nuclear and Flibe Energy. The Department of Energy said these companies could benefit from the Surplus Plutonium Utilisation Program, which is designed to help them attract private funding for reactor development and fuel production projects.

The plan marks a major policy shift from earlier efforts aimed at diluting and permanently disposing of excess plutonium. In May last year, President Donald Trump ordered a halt to much of the disposal programme and pushed for the material to instead be used as reactor fuel. Supporters of the move argue that the plutonium can be turned into a valuable energy resource rather than being treated only as nuclear waste.

However, the proposal has also faced criticism from several Democratic lawmakers and nuclear safety experts. In a letter sent in September, Senator Edward Markey of Massachusetts and Representatives Don Beyer of Virginia and John Garamendi of California raised concerns over the security risks linked to the plan. They pointed out that 20 metric tonnes of weapons-grade plutonium could potentially be enough for nearly 2,000 nuclear bombs.

The lawmakers warned that the decision “raises serious weapons proliferation concerns, makes little economic sense, and may adversely affect the nation’s defence posture”, while urging the Department of Energy to cancel the programme. Their concerns focused on the possibility of the material being misused and the broader risks connected to handling such a large amount of weapons-usable plutonium.

Despite the criticism, officials and companies involved in the programme believe the initiative could help accelerate the development of advanced nuclear reactors in the United States. Oklo cofounder and CEO Jacob DeWitte said the plan would make use of material that had originally been marked for disposal.

“This program creates a pathway to use existing surplus material as bridge fuel for advanced reactors to bring more reactors online sooner,” said Oklo cofounder and CEO Jacob DeWitte. “Material that has been set aside for disposal can instead be converted into fuel to produce electricity.”

Stefano Buono, CEO and founder of Newcleo, also supported the initiative and said the use of plutonium as reactor fuel could help reduce the burden of nuclear liabilities in the United States.

The programme has also drawn attention because US Energy Secretary Chris Wright previously served on Oklo’s board of directors before joining Trump’s cabinet. While the Department of Energy defended the programme as an opportunity to strengthen advanced nuclear energy development, it did not immediately respond to questions about the specific safety measures that would be used to manage and transport the plutonium.

The initiative comes at a time when the US is increasing its focus on advanced nuclear technology as part of its long-term energy strategy. Supporters believe the programme could help bring more reactors online and strengthen clean energy production. Critics, however, continue to warn that the risks connected to weapons-grade plutonium remain significant and require strict oversight.