Nuclear Waste Cleanup: DOE Needs to Improve the Accuracy of Cost and Schedule Information for Major Projects and Activities

What GAO Found

The Department of Energy's (DOE) Office of Environmental Management (EM) manages cleanup of hazardous and radioactive waste through capital asset projects and operations activities. Capital asset projects have defined start and end points, whereas operations activities are typically routine or reoccurring. As of August 2025, EM estimated costs for the most expensive capital asset projects ranging from $69 million to $18.5 billion, and costs for the most expensive operations activities ranging from $1 billion to $177 billion. EM's data indicated that combined costs for the most expensive capital asset projects increased by more than $2 billion, and combined costs for the most expensive operations activities increased by about $75 billion since GAO last reported in 2022. EM officials said that these cost increases were already known to the agency and accounted for in previous life-cycle cost estimates that were communicated to Congress. As of May 2025, EM estimated that the remaining cleanup work at all its sites would cost more than half a trillion dollars.

EM has seen cost increases and schedule delays due to multiple factors, and the office struggles to maintain complete documentation and reconcile data discrepancies. Specifically, key project documents are not consistently accessible for headquarters review in DOE's project management database. These documents could provide valuable information on reasons behind increases and recommendations to address underlying issues. Similarly, EM faces challenges providing current cost and schedule information for operations activities that is consistent across headquarters and sites, and EM officials could not easily coordinate to reconcile the inconsistencies. Ensuring availability of complete project information and improving coordination to address the accuracy and consistency of cost and schedule information will help EM manage its projects and activities, report more accurate information to Congress, and provide support to sites.

Even if EM improves the completeness and consistency of information on its projects and activities, its cost and schedule estimates may still reflect significant uncertainty. EM officials from several sites told GAO that final cleanup remedies at their sites still need to be determined, which may increase costs and schedules. GAO has reported that significant cost and schedule savings are still possible on several cleanup projects and activities.

Table: Potential Savings Identified for Selected Office of Environmental Management Capital Asset Projects and Operations Activities

Source: GAO analysis of Department of Energy data. | GAO-26-107820

Why GAO Did This Study

EM is responsible for the cleanup of sites and facilities contaminated from decades of nuclear weapons production and nuclear energy research. GAO has identified DOE's project management and environmental liability-or expected cleanup costs-as High-Risk areas. The department's management and oversight record has left DOE vulnerable to fraud, waste, abuse, and mismanagement, and its expected future cleanup costs have ballooned over the last several decades.

Senate Report 118-58 includes a provision for GAO to provide a biennial report on the status of EM's major projects and operations activities. This report (1) describes the status of EM's largest capital asset projects and operations activities, including changes since GAO's 2022 report; and (2) examines challenges and opportunities to improve the performance of EM's largest capital asset projects and operations activities.

GAO analyzed documents and data and compared information with DOE and EM requirements for managing projects and operations activities. GAO also interviewed EM officials.