After senior and junior partners Fluor [FLR] and Amentum, the new prime contractor for the National Nuclear Security Administration’s (NNSA) main weapons production sites, also includes Criterion Systems, General Atomics, and SOC, Fluor said this week.

Fluor, which has a 60% stake in new prime Nuclear Production One (NPOne), announced some more of the details of its winning bid a day after sister publication the Exchange Monitor first reported that NPOne beat out bids from BWX Technologies [BWXT], Lynchburg, Va., and Bechtel National, Reston, Va., to claim the potentially 10-year, $28-billion contract to manage the Pantex Plant in Amarillo, Texas, and the Y-12 National Security Site in Oak Ridge, Tenn.

SOC is the only one of those companies that’s part of incumbent production office prime Consolidated Nuclear Security, the Bechtel-led joint venture that the NNSA decided in 2020 to remove from the site.

The incumbent is leaving three years of options on the table, but will remain at Y-12 to continue building the Uranium Processing Facility: a new NNSA factory that will help produce nuclear weapon secondary stages, replacing the World War II-vintage Building 9212. The agency has said the new facility will be finished by 2025 and cost no more than $6.5 billion.

The award to NPOne continues a hot streak for the ascendant Fluor, which in a matter of two years has gone from weighing the sale of its government contracting business to adding some stability from the civilian defense-nuclear complex with wins at the Naval Nuclear Laboratory and now Pantex and Y-12.

The award also gives Amentum, fresh off a big win to continue weapons cleanup at Oak Ridge, another toehold in the NNSA complex. The company is still a partner on the management and operations contract for the Lawrence Livermore National Laboratory, which had been its last remaining NNSA site after Los Alamos National Security left the Los Alamos National Laboratory in 2018.

Meanwhile, no losing bidder had protested the award to NPOne as of Wednesday afternoon. Spokespersons from BWX Technologies and Bechtel did not immediately reply to requests for comment.

“The selection of the new contractor was made with great care,” NNSA Administrator Jill Hruby wrote in an email to agency hands on Monday.

Last year, Bob Raines, NNSA’s associate administrator for acquisition and project management, vowed that agency’s decision on the new production office contractor, once made, would be final.

“We don’t get protested,” Raines said at the time.