MOX, High Flyer Photo

An aerial view of the Mixed Oxide Fuel Fabrication Facility, which is located at the Savannah River Site.

The death of the over-budget and past-due Mixed Oxide Fuel Fabrication Facility was more a blessing than a curse, the federal government argued in a recent Supreme Court brief, at the same time urging the high court to dismiss South Carolina's petition for legal review.

Ending the MOX project – never completed, more than a decade in the making and costing billions of dollars – actually lessens nuclear repercussions in the Palmetto State, according to the federal government's Sept. 11 court filing.

"Indeed, the decision to halt construction of the MOX facility reduces the likelihood of injury by allowing the department to focus its resources on other disposal methods that can begin more quickly and with greater certainty," it reads in part.

MOX was nixed in October 2018 by the U.S. Department of Energy's semiautonomous weapons and nonproliferation agency, the National Nuclear Security Administration. The facility was being built at the Savannah River Site, a sprawling nuclear reserve directly south of Aiken and hours northwest of Charleston.

The NNSA's chop landed five months after U.S. Secretary of Energy Rick Perry informed congressional defense committees of his intent to terminate the already halting venture.

South Carolina officials have often argued that ending MOX would render the state a toxic waste dump. But the secretary's decision to abandon the facility does not equate to the abandonment of nuclear material in South Carolina, the federal government stated in its brief. 

MOX, the product of a 2000s-era pact between the U.S. and Russia, was meant to turn 34 metric tons of weapons-grade plutonium into nuclear fuel. While many metric tons of surplus plutonium are right now kept at the Savannah River Site, only some of the cache was destined for MOX, an administration official told the Aiken Standard earlier this year.

A majority of the the MOX-bound defense plutonium never reached SRS, the same official said.

Shortly after Perry's announcement last year, South Carolina sued the Energy Department and its officials to prevent a MOX shutdown. A federal judge initially sided with the Palmetto State, shielding project construction. But an appeals court did not.

One day after the appeals court lifted the lower court's protections – a decision South Carolina's legal team is asking the Supreme Court to review – termination notices were delivered to MOX contractors and guarantors.

Both Perry and NNSA chief Lisa Gordon-Hagerty have championed dilute-and-dispose as MOX's replacement. That plutonium disposition method involves mixing the metal with inert material and shipping the product to southeastern New Mexico for long-term storage by way of burial.

"The secretary certified 'that an alternative option for carrying out the plutonium disposition program for the same amount of plutonium intended to be disposed of in the MOX facility exists,' noting that the department could use the dilute and dispose method as it is doing with other plutonium at the SRS site," the federal government said in its Supreme Court filing.

In an interview with the Aiken Standard earlier this summer, Gordon-Hagerty described dilute-and-dispose as the superior approach. Perry, the energy secretary, certified to Congress that MOX would cost roughly double what dilute-and-dispose would.

South Carolina officials, though, have been highly critical of the MOX alternative and the process by which the project was curbed. U.S. Sen. Lindsey Graham, R-S.C., has described dilute-and-dispose as half-baked and as a "pie in the sky."

S.C. Gov. Henry McMaster, another Republican, has said similar things. Both McMaster and Graham have met with President Donald Trump about MOX.

In July, Graham filed an amicus brief formally aligning himself with the Palmetto State's legal arguments. The Senate Judiciary Committee chairman urged the Supreme Court to hear the matter.

"The federal government previously made legally binding commitments to the state of South Carolina in recognition of its sovereign status and its proprietary interests," Graham argued in the brief. "It has now breached those commitments, causing injury to the state that a court may redress."

Colin Demarest covers the Savannah River Site, the U.S. Department of Energy, the National Nuclear Security Administration and government in general. Follow him on Twitter: @demarest_colin