The Department of Energy said Thursday it will produce nuclear-warhead cores for the ongoing 30-year, $1 trillion modernization of the U.S. nuclear arsenal at two sites instead of one, and will convert a major nonproliferation facility into a weapons plant to do it.

The Department of Defense wants DoE to make 80 fissile “plutonium pits” per year by 2030. The Energy Department previously planned to concentrate the work at the Los Alamos National Laboratory, but now will split the mission between the northern New Mexico site and a repurposed plutonium-disposal plant at the Savannah River Site in Aiken, S.C.

Under the so-called “two-pronged” approach announced Thursday — and telegraphed last year in an internal DoE report that leaked to the press — the department said it will convert the Mixed Oxide Fuel Fabrication Facility (MFFF) into a sophisticated metallurgy facility capable of producing 50 pits a year by 2030. It would spell the end of the MFFF as the world knows it today.

It was not clear exactly how much it will cost to convert the MFFF for pit production, or how DoE would procure the services needed to do it. The department and its semiautonomous National Nuclear Security Administration did not reply to requests for comment about the agency’s procurement plans for the proposed pit-producing MFFF.

The Los Alamos National Laboratory, meanwhile, will get a multibillion-dollar investment in new plutonium facilities designed to produce at least 30 pits a year, DoE said Thursday. The agency has said it plans to hit this level of throughput at Los Alamos by 2026.

In a statement Thursday, Los Alamos National Laboratory Director Terry Wallace said the planned New Mexico facilities would be capable of a “surge capacity” that could boost pit production “up to 80 pits per year.” On Friday, Wallace blasted out a second statement walking back the specific claim. According to the Friday statement, surge capacity would “maximize pit production.”

A lab spokesperson would not comment further about the surge capacity and deferred to Friday’s statement when pressed. The Energy Department would not comment about any surge capacity at Los Alamos, and did not describe any such capacity in either the press release or pit fact sheet it published Thursday.

The two-pronged approach is “the best way to manage the cost, schedule, and risk of such a vital undertaking,” DoE said Thursday in its joint press release with the Department of Defense. Splitting the pit mission between two sites “improves the resiliency, flexibility, and redundancy of our Nuclear Security Enterprise by not relying on a single production site,” the agencies stated.

Meanwhile, elected officials from both New Mexico and South Carolina found something to dislike about DoE’s plutonium-pit plan.

South Carolina lawmakers, reinforcing positions they staked out last year after DoE’s report about a two-pronged pit strategy leaked, said they welcome the pit work, but oppose canceling the MFFF’s current nonproliferation mission.

“We are extremely disappointed to hear the Department of Energy plans to abandon the MOX [MFFF] program,” a cadre of South Carolina members of Congress, led by Sens. Lindsey Graham (R) and Tim Scott (R), wrote in a statement Friday. “We plan to hold DoE accountable for this haphazard decision and will press for oversight,” the lawmakers said.

Also signing the South Carolina statement were Republican Reps. Joe Wilson, Jeff Duncan, Tom Rice, Ralph Norman, and Trey Gowdy.

New Mexico Sens. Tom Udall (D) and Martin Heinrich (D), plus Reps. Ben Ray Luján (D) and Michelle Lujan Grisham (D), said they were “pleased” DoE would continue to invest in new pit facilities at Los Alamos. However, the lawmakers said in a joint statement, taking any pit work away from the lab “will set back our military’s life extension programs and stretch the Lab’s existing facilities and workforce to its limits.”

The DoE press release alone does not clear the way for the agency’s two-pronged pit program. First, the agency must obtain a waiver from Congress to cancel the MFFF’s current plutonium disposal mission. To get the waiver, DoE must prove that an alternative plutonium disposal strategy would cost about half as much as just finishing the MOX plant.

Last week, a DoE official said the agency would deliver a cost estimate for a proposed MFFF alternative, called dilute-and-dispose, in June. The estimate is a key part of obtaining the waiver DoE seeks.

Spokespersons for the House and Senate Armed Services Committees did not reply to requests for comments about whether DoE has formally requested a waiver to cancel the facility. Nevertheless, a source said Friday that DoE planned to halt construction on MFFF in about a month.

By the most optimistic estimate in the public sphere, the MFFF is more than a decade behind schedule and roughly $5 billion over budget. The facility was designed to turn 34 metric tons of surplus weapon-usable plutonium — most of which is in pit-form — into commercial reactor fuel as part of an arms-control agreement finalized with Russia in 2010.

The Energy Department has already spent $5 billion on the project. It claims it can deweaponize the plutonium faster and cheaper with dilute and dispose. That approach would involve building new facilities at the Savannah River Site’s K-Area to chemically weaken the 34 metric tons of plutonium below weapon-grade, mixing the resulting material with concrete-like grout, and burying the mixture deep underground at DoE’s Waste Isolation Pilot Plant near Carlsbad, N.M.

Canceling the MFFF and repurposing the plant to manufacture pits requires approval from both authorizors and appropriators in Congress. Complicating the situation, both South Carolina and MFFF prime contractor CB&I AREVA MOX Services have sued the agency in court over MFFF in an effort to keep the project’s current nonproliferation mission alive.

South Carolina Gov. Henry McMaster (R) has threatened to drag DoE to court again if the agency cancels MFFF. McMaster’s office did not reply to multiple requests for comment.