The U.S. is exploring the use of Cold War-era plutonium from dismantled nuclear warheads as alternative fuel for advanced nuclear reactors due to uranium supply shortages and reliance on foreign enriched uranium.

The Trump administration is reportedly in talks with five companies to provide old plutonium to convert into fuel for future nuclear reactors.

Companies say it’s a better way to dispose of the Cold War-era material — and fix a shortage of nuclear fuel. But the plan has also faced criticism.