WASHINGTON — Major construction projects for the National Nuclear Security Administration (NNSA) have seen cost overruns more than double since 2023, a report from a government watchdog found.
“NNSA’s major construction cost overruns grew since our last assessment in 2023 — rising from $2.1 billion to $4.8 billion,” a Government Accountability Office report released today says. “And delays have grown, too, from 9 years to 30 years, as of June 2025. Management, vendor, and input costs all contributed to cost growth and delays.”
The NNSA is a semi-autonomous agency under the Department of Energy and is responsible for the maintenance and modernization of the US’s nuclear weapons stockpile, while delivery of those weapons falls under the Department of Defense.
The report, entitled “Nuclear Security Enterprise: Assessments of NNSA Major Projects,” is the second biennial report on the NNSA by the GAO. The Senate ordered biennial reviews as part of the National Defense Authorization Act for FY23. The GAO reports have focused on scrutinizing the projects in the “Execution Phase,” which are under previously approved metrics for costs and timelines. Meanwhile, the watchdog has been determining the level of development and maturity for projects in the “Definition Phase,” which do not yet have approved cost and schedule baselines and are still moving through design development before full construction begins.
NNSA is currently managing 28 major construction projects — each of them costing at least $100 million — with the total estimated cost of the entire portfolio being at least $30 billion, per GAO’s report. Among those, 16 are in the Execution Phase and the remaining 12 are in the Definition Phase. Of the total construction projects, 17 were highlighted as facing some issue such as cost, delay, redesign, or being paused.
Nine of the projects in the Execution Phase have, or are expected to have, a cost overrun of at least 20 percent by the time of completion. Furthermore, two of the major projects in this phase, the Uranium Processing Facility (UPF) and UPF Salvage and Accountability Building at the Y-12 National Security Complex, accounted for 80 percent of the cumulative total cost overruns observed by the GAO, according to the report.
Among the 12 projects that fall under the Definition Phase, eight were identified as currently being “either on hold, implementing design changes, experiencing design challenges, or assessing the effect of these issues on their cost and schedule estimates.”
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The GAO has previously made at least 21 recommendations to the NNSA to improve performance. According to today’s report, the NNSA “agreed with most of those recommendations” but as of December has not fully addressed eight of them.
Some of the unaddressed recommendations include the development of an integrated master schedule for its plutonium production activities, which was previously included in a 2020 GAO report and remains unaddressed. Further left unaddressed is a life cycle cost estimate that aligns with “GAO cost estimating best practices,” per today’s report.
The GAO also recommended that NNSA create a comprehensive plan for the safe operation of an existing facility at the Y-12 complex until 2035 to accommodate the six-year delay in the UPF project, as one does not currently exist. The NNSA agreed with the recommendation and is taking action, but has not completely implemented the plan yet.