Federal Agency Delays $4 Million Idaho Reactor Fix

Why It Matters

The United States Navy's nuclear-powered fleet depends on a single aging reactor in eastern Idaho to test the fuel that powers its submarines and aircraft carriers. That reactor is running out of room to store its spent fuel, and the federal agency responsible for fixing the problem has yet to approve a relatively inexpensive solution sitting in its inbox.

A Government Accountability Office report released May 7 found that the Department of Energy has failed to act on a draft plan submitted by its own Idaho Operations Office that could resolve a spent fuel storage crisis threatening to shut down the Advanced Test Reactor at Idaho National Laboratory by as early as fiscal year 2030. The fix would cost roughly $4 million. The cost of inaction could be measured in naval readiness.

Broader Context

The Advanced Test Reactor has been operating at Idaho National Laboratory since 1967. It remains the only reactor in the United States capable of meeting the nuclear fuel and structural material testing requirements of the joint Navy and National Nuclear Security Administration Naval Nuclear Propulsion Program.

The Navy's Office of Naval Reactors requires 200 operational days per year from the reactor to conduct the irradiation testing that keeps the nuclear fleet certified and ready. Naval Reactors alone regularly uses more than half of the ATR's annual testing capacity.

The reactor has not consistently met that benchmark. According to GAO, from January 2015 through March 2025, the ATR operated an average of just 121 days per year, well below the 200-day requirement. Repairs, maintenance, and aging infrastructure have repeatedly interrupted operations.

Beyond Naval Reactors, the ATR serves a broader national security and scientific mission. The Department of Energy's Office of Science uses it to produce cobalt-60 for medical and defense applications. The NNSA's Office of Defense Nuclear Nonproliferation uses it to test high-assay low-enriched uranium fuel. NASA relies on ATR-produced plutonium-238 to power deep space missions.

The Advanced Test Reactor Spent Fuel Problem

The more immediate crisis is storage. The ATR generates spent nuclear fuel that must be moved from the reactor's spent fuel canal into a long-term storage facility at the Idaho Nuclear Technology and Engineering Center, known as INTEC Building 603.

As of May 2025, INTEC Building 603 held 3,432 spent ATR fuel elements, amounting to approximately three metric tons. The facility is approaching its capacity limit. If nothing changes, GAO projects it will be full sometime between fiscal years 2028 and 2030, at which point the ATR's spent fuel canal would also be full, and the reactor would have to stop operating.

The ATR's spent fuel canal can hold approximately 800 elements in the short term, and it too is nearing capacity. Under the terms of a 2020 addition to the 1995 Idaho Settlement Agreement, spent fuel generated after January 1, 2018, may only remain in the ATR canal for six years, adding another layer of legal constraint.

The DOE's Idaho Operations Office submitted a draft plan in February 2025 to reconfigure portions of INTEC Building 603. The estimated cost is $4 million. If completed alongside a packaging demonstration project, the plan would allow ATR spent fuel transfers to continue until approximately 2085. As of the report's publication, senior leadership from DOE's Offices of Environmental Management and Nuclear Energy had not completed their evaluation of the plan.

GAO issued one recommendation: the Secretary of Energy should direct the Office of Nuclear Energy, in coordination with the Office of Environmental Management, to complete its evaluation of the reconfiguration plan before ATR operations are interrupted.

DOE concurred with the recommendation.

A Billion-Dollar Maintenance Problem Behind the $4 Million Fix

The spent fuel storage issue is the most urgent problem, but it sits inside a larger, more expensive challenge.

The ATR is aging. Its core internals require a full changeout every seven to ten years, a process that shuts the reactor down for six to twelve months. Replacing heat exchangers in the primary cooling system would cost more than $140 million. Replacing the Liquid Warm Waste Treatment Facility and underground piping could run $97 million.

Between 2019 and 2022, DOE explored three long-term options through its Thermal Test Reactor Capability project: maintain and repair the ATR, modify it to improve performance, or replace it entirely with a new reactor. Initial cost estimates ranged from $2.8 billion to $11.1 billion in fiscal year 2022 dollars. A May 2022 independent cost review by DOE's Office of Project Management put the range at $9 billion to $24 billion.

Faced with those figures, DOE leadership directed in June 2024 that TTRC project funding not be included in the fiscal year 2026 budget request. By January 2025, the Office of Nuclear Energy concluded that maintaining the ATR without a major construction project was feasible, at least through the early 2050s and potentially until 2085. That maintenance approach is estimated to cost approximately $1.26 billion over 20 years, from fiscal year 2027 through fiscal year 2044.

The TTRC project was formally suspended in December 2025 but was not permanently canceled. DOE officials told GAO it could resume if fiscal conditions improve.

Congressional Pressure and the Idaho Settlement

The report was mandated by the Senate Armed Services Committee through Senate Report 118-188, accompanying the fiscal year 2025 National Defense Authorization Act. The report was addressed to the Senate Armed Services Committee, the Senate Appropriations Subcommittee on Energy and Water Development, the House Armed Services Committee, and the House Appropriations Subcommittee on Energy and Water Development.

The Idaho dimension adds legal weight to the urgency. Under the 1995 Idaho Settlement Agreement, including a 2008 Navy addendum, DOE is committed to shipping all spent nuclear fuel out of Idaho by January 1, 2035. Missing that deadline triggers a penalty of $60,000 per day.

Naval Reactors officials told GAO they are working with DOE to determine whether the ATR can support all required irradiation testing deliverables beyond 2040. That assessment is expected to be completed within the next 18 months. DOE plans to begin requesting maintenance funding through the ATR operations and maintenance budget starting in fiscal year 2027, meaning the current fiscal year 2026 budget is insufficient to begin the new maintenance approach.

The GAO's core finding is that a $4 million administrative decision, long delayed, stands between the Navy's nuclear fuel testing program and an operational shutdown that no budget line can easily reverse.

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