US Military Airlifts a Nuclear Microreactor for the First Time as Three Companies Race to Hit Criticality by July Fourth
Operation Windlord flew Valar Atomics' Ward250 reactor from California to Utah on three C-17s, kicking off an executive-order sprint to power military bases and data centers with factory-built nuclear plants.
Overview
On February 15, the United States Air Force loaded a nuclear microreactor onto a C-17 Globemaster III and flew it nearly 700 miles from California to Utah — the first time a nuclear reactor of any kind has been transported by military aircraft. The operation, designated “Operation Windlord,” moved Valar Atomics’ Ward250 reactor in eight modules across three C-17 flights from March Air Reserve Base to Hill Air Force Base, according to The War Zone. From there, the reactor will travel to the Utah San Rafael Energy Lab for assembly and testing.
The airlift is the most visible milestone yet in a broader push by the Trump administration to deploy portable nuclear power plants at military installations and, eventually, at commercial sites such as data centers. An executive order signed in May 2025 set an ambitious target: achieve criticality in at least three test reactors by July 4, 2026, using the Department of Energy’s authorization process, as reported by World Nuclear News.
What We Know
The Ward250 is a helium-cooled, graphite-moderated microreactor that uses TRISO fuel — uranium kernels encased in multiple layers of ceramic — which is designed to withstand extreme temperatures without melting, according to The War Zone. At full capacity the reactor is rated at 5 megawatts of electricity, enough to power roughly 5,000 homes, though its initial testing phase will operate at far lower output, starting at 100 kilowatts thermal and scaling to 250 kilowatts later in 2026, as reported by Interesting Engineering.
The reactor was transported without nuclear fuel. Fuel will be shipped separately from the Nevada National Security Site once the Utah facility is ready to begin operations, according to NPR.
Energy Secretary Chris Wright and Michael Duffey, Under Secretary of Defense for Acquisition and Sustainment, were both present at March Air Reserve Base for the departure. “Today is history,” Wright said, according to NPR. “A multi-megawatt, next-generation nuclear power plant is loaded in the C-17 behind us.” Duffey framed the reactor in operational terms: “This gets us closer to deploying nuclear power when and where it is needed to give our nation’s warfighters the tools to win in battle,” as quoted by Interesting Engineering.
The 62nd Airlift Wing, the only Air Force unit certified for routine transport of nuclear weapons, conducted the mission, lending the operation additional institutional weight, as noted by The War Zone.
The Broader Microreactor Race
Valar Atomics is not working alone. The Department of Energy is supporting at least three microreactor developers for testing at the DOME facility inside Idaho National Laboratory’s former Experimental Breeder Reactor II containment structure, according to the U.S. Department of Energy.
Westinghouse’s eVinci, rated at up to 5 megawatts, uses hundreds of specialized iron-chromium-aluminum heat pipes for passive cooling and is designed to run for more than eight years without refueling. Radiant’s Kaleidos, a 1.2-megawatt design, fits inside a single shipping container and targets diesel generator replacement at hospitals, military bases, and data centers. Antares’ R1, the smallest of the three at 200 to 300 kilowatts, is passively cooled by sodium heat pipes and designed for remote terrestrial and space environments, as detailed by the Department of Energy.
On the military side, the Army’s Janus Program has identified nine installations — including Fort Bragg, Fort Drum, Fort Hood, and Joint Base Lewis-McChord — as candidates for microreactor deployment, according to a U.S. Army announcement. The program describes the technology as “safe by design, not by intervention protocols” and aims to deliver resilient energy that does not depend on vulnerable civilian power grids.
What We Don’t Know
The July 4 deadline for criticality is widely regarded as aggressive. Valar Atomics achieved zero-power criticality at Los Alamos National Laboratory in November 2025 with its NOVA Core, making it the first company to reach that milestone under the DOE’s Reactor Pilot Program, according to World Nuclear News. However, zero-power criticality is a controlled chain reaction at negligible energy output — far removed from the hot, full-power operation needed to prove a reactor can deliver electricity reliably.
Former DOE Assistant Secretary Katy Huff told Neutron Bytes that “a zero-power criticality test can be achieved without making real engineering progress,” emphasizing that the median timeline from construction start to operational status for nuclear projects is roughly two years.
The cost and practicality of air transport have also drawn scrutiny. The three C-17 flights cost approximately $225,000 to move what was essentially a non-fueled prototype, according to Neutron Bytes. By comparison, Radiant’s one-megawatt Kaleidos is designed to ship in a single aircraft, raising questions about the Ward250’s deployment efficiency.
Edwin Lyman of the Union of Concerned Scientists characterized the airlift as a “dog-and-pony show,” citing unresolved questions about feasibility, economics, safety, and secure transport once nuclear fuel is involved, as reported by NPR. Nuclear engineer Nick Turan has calculated that spent TRISO fuel from a Ward-class reactor would deliver lethal radiation doses within milliseconds of unshielded contact, contradicting statements by Valar founder Isaiah Taylor about fuel safety, according to Neutron Bytes.
What Comes Next
Valar Atomics plans to begin trial power sales in 2027 and targets full commercial operation by 2028, according to NPR. The company’s immediate priority is assembling the Ward250 at the Utah San Rafael Energy Lab and securing DOE authorization to load fuel.
The broader commercial case for microreactors rests on the premise that factory-built, truck- or aircraft-transportable reactors can be manufactured at scale and deployed faster and more cheaply than traditional nuclear plants. Proponents point to surging electricity demand from artificial intelligence data centers as a market that conventional generation cannot fill quickly enough.
Whether any of the three companies in the DOE pilot program will meet the July 4 criticality target remains an open question. What is no longer in question is that the United States military has demonstrated it can move a nuclear reactor by air in under two hours — a capability that, if the technology matures, could reshape how both the armed forces and the civilian economy think about portable power.