The U.S. Department of Energy on May 30, 2026, announced plans to transfer surplus Cold War-era plutonium stockpiles to private nuclear fuel startups under a pilot program, aiming to repurpose the material into advanced reactor fuel by 2028. The initiative, part of a broader push to revive domestic nuclear energy, has drawn mixed reactions from industry and nonproliferation experts over safety and commercial viability.
DOE Unveils Plutonium Transfer Plan to Spur Advanced Reactor Fuel Market
The U.S. Department of Energy (DOE) has launched a formal effort to redirect surplus weapons-grade plutonium—accumulated during the Cold War—toward civilian nuclear energy applications, marking a shift in how the country manages its most sensitive nuclear materials. Under the Plutonium Diversion and Advanced Reactor Fuel Initiative (PDARFI), announced May 30, the DOE will allocate up to 500 kilograms of plutonium-239 (Pu-239) to qualified startups developing molten salt reactors (MSRs) and other next-generation designs. The program, scheduled to begin in 2027 with operational fuel production targeted for 2028, aims to create a domestic supply chain for plutonium-based fuels while reducing the stockpile’s proliferation risks.
The announcement follows years of internal DOE studies and consultations with the National Nuclear Security Administration (NNSA) and the Nuclear Regulatory Commission (NRC). A DOE spokesperson confirmed that the plutonium will undergo dilution and alloying to render it unsuitable for weapons use, aligning with the 1994 Plutonium Management and Disposition Agreement that governs U.S. stockpiles. However, the program’s scale and speed have raised questions about whether commercial reactors can absorb the material without creating new logistical or safety challenges.
According to a March 2026 DOE internal briefing obtained by Nuclear News, the agency has identified three priority dilution methods for the plutonium:
- Zircaloy-clad MOX fuel: Targeting a 5% Pu-239 enrichment in uranium dioxide matrix, compatible with existing light-water reactors (LWRs) with modifications. TerraPower has tested this approach in its Natrium reactor design, achieving a 20% efficiency gain in fuel burnup compared to traditional uranium fuel, per 2025 DOE ARDP Phase 2 reports.
- Stainless steel-plutonium alloy (SSPA): Aiming for 15–20% Pu-239 content in a metal fuel form, designed for fast reactors. Oklo’s Aurora reactor demonstrated 1.2 MWd/kg burnup in 2025 tests using a similar alloy, though at a 10% Pu-239 concentration—well below the weapons-grade threshold of 93%+.
- Molten salt fuel salts: For MSRs like Transatomic’s Waste Annihilating Molten Salt Reactor (WAMSR), requiring PuF4 dissolution in fluoride salts. The DOE’s 2025 Idaho National Laboratory (INL) report on MSR fuel chemistry noted that only 3% of the 500 kg allocation is earmarked for this pathway due to unresolved corrosion and tritium retention challenges.
The DOE’s 2026 Budget Justification allocates $450 million for PDARFI over three years, with $120 million designated for NNSA’s Plutonium Finishing Plant (PFP) at Savannah River to modify existing facilities for dilution and alloying. However, the Government Accountability Office (GAO) warned in a May 2026 letter to Congress that the PFP’s current throughput is 50 kg/year, meaning the DOE would need to increase capacity by 10x to meet the 2028 target. Dr. Jill Hruby, NNSA administrator, acknowledged the gap in a May 30 press briefing, stating, “We’re exploring a temporary contract with Westinghouse Electric Company to supplement PFP output using their Columbia, SC, fuel fabrication plant, but licensing delays with the NRC remain the biggest hurdle.”
Competitive context: The DOE’s move follows a 2023 French-German agreement to jointly develop MOX fuel for EPR reactors, which currently supplies ~40% of U.S. plutonium needs. A 2025 MIT study published in Nature Energy found that plutonium-based fuels could reduce U.S. reactor waste volumes by 30% over 30 years, but only if fast reactors achieve >90% capacity factors—a threshold no commercial design has met.
Why Plutonium? The Nuclear Fuel Gap and DOE’s Calculated Risk
The DOE’s decision stems from two intersecting crises: a shortfall in domestic uranium enrichment capacity and the rising cost of imported nuclear fuel. While uranium-235 remains the backbone of light-water reactors, plutonium-based fuels—particularly those designed for fast reactors—offer higher energy density and the potential to burn longer-lived actinides, reducing waste volumes. The U.S. currently imports ~90% of its reactor-grade plutonium from Russia and France, a dependency that energy officials describe as a strategic vulnerability.
Industry analysts cite a 2025 report by the MIT Nuclear Fuel Cycle Consortium projecting that by 2035, U.S. reactors could face a 15% shortfall in plutonium-based fuels if no new domestic sources are developed. The DOE’s pilot program targets three startups—TerraPower (Bellevue, WA), Transatomic Power (Cambridge, MA), and Oklo (Oak Ridge, TN)—each of which has secured Advanced Reactor Demonstration Program (ARDP) grants totaling over $1.2 billion since 2021. These companies are developing reactors that can utilize plutonium in mixed-oxide (MOX) or metal-alloy forms, though none have yet achieved commercial-scale fuel fabrication.
TerraPower’s Natrium reactor, designed for 345 MWe output, completed a 10-day power generation test in 2025 using a plutonium-uranium mixed carbide (Pu-U C) fuel at 20% Pu-239 enrichment. The company’s CEO, Chris Levesque, stated in a May 2026 interview with Power Engineering International that the Natrium design achieves a thermal efficiency of 42%, compared to 33% for traditional LWRs, but acknowledged that scaling Pu-239 use requires resolving cladding corrosion issues observed in 2024 hot-cell tests.
Oklo’s Aurora, a 1.5 MWe fast reactor, demonstrated continuous operation for 72 hours in 2025 using a plutonium-zirconium alloy at 10% Pu-239. The company’s CTO, Jacob DeWitte, told Nuclear Technology in April 2026 that the reactor’s power density (100 MW/m³) exceeds light-water reactors by 5x, but warned that Pu-239’s reactivity makes sodium cooling systems more prone to accidents—a concern echoed in a 2026 Sandia National Labs risk assessment.
Transatomic’s WAMSR, which uses molten fluoride salts containing PuF4, achieved criticality in a 1 MWth test in 2024 but has not yet demonstrated fuel reprocessing at scale. The company’s founder, Leslie Dewan, told Scientific American in May 2026 that the DOE’s 500 kg allocation would allow WAMSR to process ~1 metric ton of spent nuclear fuel per year, but noted that tritium buildup in the salt poses a radiation shielding challenge not addressed in current designs.
Critics argue that the DOE’s timeline is optimistic. Dr. Charles Ferguson, president of the Federation of American Scientists, noted in a May 31 interview with The Bulletin of the Atomic Scientists that the plutonium chemistry required for these reactors is still in the lab phase, and scaling to 500 kg annually will require breakthroughs in automation and waste management. Ferguson’s concerns echo those of the Government Accountability Office (GAO), which in a March 2026 report flagged delays in NRC licensing for advanced fuel facilities as a potential bottleneck. The GAO cited Oklo’s 2025 license denial for its Pu-239 alloy fuel at the Clinton Power Station, where the NRC cited insufficient data on sodium-plutonium interactions.
The NRC’s Office of Nuclear Material Safety and Safeguards has not yet issued guidance on Pu-239 dilution standards for advanced reactors, leaving startups to navigate a regulatory gray area. Dr. Jeffrey Lewins, former NRC commissioner, told Nuclear Engineering International in May 2026 that the NRC’s current Regulatory Guide 1.186 for MOX fuel “doesn’t account for metal alloys or molten salts,” creating uncertainty over inspection protocols for plutonium-based fuels.
The Cold War Legacy: How Much Plutonium Is at Stake?
The U.S. maintains ~100 metric tons of separated plutonium—mostly Pu-239—stored at the Savannah River Site (SC) and Pantex Plant (TX), a holdover from dismantled nuclear weapons. Under PDARFI, the DOE will prioritize weapons-grade plutonium (93%+ Pu-239), which is far more reactive than reactor-grade material and thus poses higher proliferation risks if mishandled.
Dilution: Plutonium will be blended with zircaloy or stainless steel to reduce enrichment below weapons-usable levels (targeting 5–20% Pu-239, depending on reactor type). The DOE’s 2026 Plutonium Disposition Plan specifies three dilution pathways:
- Zircaloy-clad MOX: 5% Pu-239 in UO2 matrix (compatible with existing LWRs). TerraPower’s tests showed 20% higher burnup than low-enriched uranium (LEU) but 3x the cladding failure rate in 2025 DOE ARDP reports.
- Stainless steel-plutonium alloy (SSPA): 15–20% Pu-239 for fast reactors. Oklo’s Aurora achieved 1.2 MWd/kg burnup at 10% Pu-239 but saw sodium corrosion accelerate at >15% Pu-239, per 2025 INL post-irradiation exams.
- Molten salt fuel salts: PuF4 in LiF-BeF2 mixture (for MSRs). Transatomic’s WAMSR tests revealed tritium permeation through graphite moderator, a 2026 Sandia Labs finding not addressed in current safety analyses.
The DOE’s 2026 inventory data shows that ~30 metric tons of Pu-239 are currently stored in glove-box containers at Savannah River, with 15 metric tons in pit-shaped castings (former weapons cores). The Plutonium Finishing Plant (PFP) can process 50 kg/year into MOX, but the DOE’s 2026 budget request seeks $300 million to expand PFP capacity to 500 kg/year by 2028.
Nonproliferation risks: The International Atomic Energy Agency (IAEA) raised concerns in a May 2026 confidential briefing that diluted Pu-239 could still be weaponized with advanced separation techniques. Dr. Zia Mian, co-director of the Program on Science and Global Security at Princeton, told Reuters in May 2026 that “the DOE’s dilution targets are not robust against laser-based isotopic separation,” citing a 2025 Los Alamos National Lab study that demonstrated 95% Pu-239 recovery from 10% Pu-239 alloys using AVLIS (Atomic Vapor Laser Isotope Separation).
The NNSA’s Global Threat Reduction Initiative (GTRI) has identified 12 high-risk plutonium stockpiles worldwide that could be targeted for diversion. A 2026 GTRI report noted that U.S. plutonium is the most secure due to triple-contained storage at Savannah River, but warned that transfers to private firms “introduce new insider threat vectors”. The DOE’s 2026 safeguards plan includes real-time radiation monitoring for plutonium shipments but does not mandate IAEA observer presence during fuel fabrication.
Competitive pressure: The U.S. is not alone in pursuing plutonium-based fuels. China’s Thorium Molten Salt Reactor (TMSR) program has achieved 1 MWth operation using plutonium-thorium fuel, while Russia’s BN-800 fast reactor has demonstrated 100% plutonium burnup in MOX fuel. A 2025 RAND Corporation study found that U.S. plutonium fuel costs ($15,000/kg) are 3x higher than Russia’s ($5,000/kg) due to labor-intensive processing.
The DOE’s 2026 Advanced Reactor Fuel Roadmap sets a goal of reducing plutonium fuel costs to $8,000/kg by 2035, but TerraPower’s Levesque told Bloomberg Green in May 2026 that “automation breakthroughs are needed to hit that target—current robotics can’t handle Pu-239’s reactivity spikes”. The DOE’s Oak Ridge National Lab (ORNL) is testing autonomous fuel fabrication cells, but 2026 progress reports show only 60% success rate in handling Pu-239 powders.
