Groups led by BWX Technologies [BWXT] and Bechtel National have protested the Department of Energy National Nuclear Security Administration’s (NNSA) decision to award management and operations of the agency’s two main nuclear-weapons production sites to the Fluor [FLR]-led Nuclear Production One.

The Government Accountability Office filed notices online Monday that Strategic Nuclear Operators — which web searches show shares an address in Lynchburg, Va., with other BWX Technologies-affiliated groups — and Integrated Mission Delivery, had lodged protests.

Strategic Nuclear Operators also includes Huntington Ingalls Industries [HII], Honeywell [HON] and a joint-venture subcontractor comprising Texas A&M University and the University of Tennessee, while Integrated Mission Delivery, the Bechtel-led team, includes General Dynamics [GD] and Westinghouse [WX], a source said.

A spokesperson for Integrated Mission Delivery said in an email that the team “believes the Source Selection Authority’s evaluation of its proposal was concerning.” A BWX Technologies spokesperson declined to comment for this story.

Pantex is where DoE’s semiautonomous NNSA assembles, disassembles and services nuclear weapons. Y-12 is the agency’s defense uranium hub, where the NNSA manufactures nuclear-weapon secondary stages.

BWX Technologies managed the Pantex Plant in Amarillo, Texas, and the Y-12 National Security Site in Oak Ridge, Tenn., under separate contracts until outgoing incumbent, the Bechtel-led Consolidated Nuclear Security, took over the sites under a single contract in 2014.

Nuclear Production One’s contract, awarded Nov. 29, is potentially worth $28 billion over 10 years. That includes a five-year base and five one-year options. Besides Fluor, the team includes Amentum and subcontractors Criterion Systems, General Atomics and SOC.

This will mark the second time BWX Technologies has taken on NNSA’s procurement apparatus over Pantex and Y-12. The company lodged multiple protests about the NNSA’s 2012 decision to give Consolidated Nuclear Security the combined site operations contract and the ensuing slog delayed transition to the incumbent into 2014.