The Department of Energy (DOE) sent a document to Congress last week formally executing a waiver to kill a project that would have used weapons-grade plutonium and uranium oxides as fuel for electricity generation in Georgia.

The Mixed Oxides (MOX) project, which required the construction of a special facility near the Savannah River nuclear site in South Carolina, has already cost the DOE north of $7.6 billion and would likely cost the federal government tens of billions more to complete, according to the document which was seen by Reuters. Instead of reusing the weapons-grade waste, the DOE proposes to mix the waste with an inert substance and dispose of the mixture at the Waste Isolation Pilot Plant (WIPP).

Simply disposing of the waste was also proposed by the Obama administration. A disposal plan would cost $19.9 billion, Reuters reported.

Lawmakers in Georgia and South Carolina have fought for years to keep the MOX plant alive. Such a plant would have produced nearly 600 full-time jobs in the region, though preparing the radioactive waste for disposal is also expected to create 400 jobs through 2040.

According to Reuters, legislation passed in February allowed the Trump administration to proceed with the cheaper plan, as long as the cheaper plan will cost less than half of what it would cost to finish the MOX plant.

The MOX facility would have manufactured mixed oxide fuel from weapons-grade plutonium and uranium oxides. The fuel would be packaged into fuel rods that could be used in commercial nuclear plants, according to the MOX fuel fabrication facility website. Mixed Oxide fuels of plutonium and uranium have been used commercially in Europe and Japan. A MOX project pamphlet (PDF) notes that plutonium only makes up about 5 percent of a MOX fuel rod, so the rod can be used in regular commercial nuclear reactors with small modifications to provide additional radiation protection.

South Carolina newspaper The State reported last week that the National Nuclear Security Administration has proposed modifying the MOX site to build plutonium pits, which would produce cores for nuclear weapons.

According to The Journal Times, South Carolina Governor Henry McMaster vowed to fight the decision, saying, "The Department of Energy has been trying to shut down the MOX project for years, breaking a promise to the people of South Carolina and breaking federal law along the way. We will not accept it, and we will fight every step of the way to make sure South Carolina's interests are protected."