That was originally the plan for surplus weapons plutonium. In 2007 the United States started building a MOX facility at Savannah River for turning the old weapons plutonium into power reactor fuel. Its cost and time to completion ballooned far beyond original estimates and it was ultimately canceled.

"Cost estimate for MOX facility at Savannah River Site swells to $47.5 billion"

https://www.augustachronicle.com/story/news/2015/04/22/cost-...

"US MOX facility contract terminated"

https://world-nuclear-news.org/Articles/US-MOX-facility-cont...

https://en.wikipedia.org/wiki/Savannah_River_Site#MOX_Fuel_F...