US start-up Deployable Energy’s demonstration reactor, Unity, has achieved a zero-power fuelled criticality demonstration at Idaho National Laboratory (INL). It is the third Department of Energy (DOE)-authorised advanced reactor to go critical by the 4 July deadline set in President Trump’s May 2025 Executive Order (EO) 14301, Reforming Nuclear Reactor Testing at the Department of Energy.
In June, Antares Nuclear’s Mark-0 and Valar Atomics’ Ward 250 reactors also achieved criticality. Mark-0 is a high-temperature sodium heat-pipe reactor, utilising entirely passive, redundant liquid metal heat pipes instead of high-pressure liquid pumps. The core uses graphite and boron carbide control drums turned by independent actuator motors. Ward 250 is a 100 kWt high temperature gas-cooled reactor (HTGR) design that uses TRISO fuel, helium coolant and graphite moderators.
Deployable Energy is developing the Unity Nuclear Battery (UNB), a 1 MWe gas‑cooled microreactor that uses an actively cooled helium primary loop and standard low-enriched uranium dioxide fuel. It is engineered for factory manufacture and shipment in a standard 20-foot container for deployment in remote, distributed, maritime, and defence applications.
EO 14301, which established the Reactor Pilot Program (RPP), mandated that at least three advanced reactor concepts should be built and should achieve criticality by 4 July 2026. Under the RPP, companies are fully responsible for the costs of designing, building, and operating their reactors, while DOE acts as a facilitator to drastically compress development timelines. This allows startups to bypass the conventional, multi-year Nuclear Regulatory Commission (NRC) approval process for their initial test reactors. DOE initially selected 11 advanced reactor projects for RPP support, including Antares and Valar.
In August 2025, DOE established the Fuel Line Pilot Program (FLPP) to support the RPP and leverage DOE authorisation to establish a domestic nuclear fuel supply chain for testing new reactors. Five companies were selected for FLPP support.
In March, DOE and the National Reactor Innovation Center (NRIC) established the Nuclear Energy Launch Pad to promote the rapid development and implementation of advanced nuclear technologies by private industry. The Launch Pad initiative builds on the RRP and FLPP expanding support beyond authorisation to include the testing and operation necessary to scale first-of-a-kind technologies toward widescale commercial deployment. Deployable was one of four companies selected for this support. The Launch Pad companies were drawn not only from those selected for the pilot programmes but also from those that applied but were not selected.
As the first Launch Pad project to achieve the criticality milestone, Deployable’s UNB demonstrates how leveraging national laboratory resources can expedite critical experiments and reactor demonstrations. UNB achieved criticality in a record time of roughly 150 days since project kick-off with INL.
“Last week, I had the opportunity to see the Unity demonstration reactor firsthand and meet with the talented teams from Deployable Energy, INL and DOE whose work made this historic moment possible on the eve of our nation’s 250th anniversary,” said Secretary of Energy Chris Wright said. Yesterday, we accomplished a significant milestone on a timeline many thought was unachievable.”
Bobby Gallagher, Deployable Energy Co-Founder and CEO, noted: “We are proud to be a part of this historic achievement and I want to express Deployable Energy’s gratitude to the administration for setting an audacious goal to have three reactors reach criticality before July 4th, the US Department of Energy for ensuring our ability to meet this goal with safety, quality, and speed, and the Idaho National Laboratory for providing an incredible partnership in execution.”
With initial criticality using a full-scale core load now achieved, the next steps will be entering a phased testing program that includes further validating reactor physics, load following, inherent safety, and full-power operations. These tests will provide additional data to verify reactor performance and support future licensing and commercialisation efforts. Data gathered during the testing campaign will be used to support continued system validation, performance optimisation, and future deployment planning.
“Deployable Energy has set a new benchmark for execution speed in the advanced nuclear sector,” said INL Director Dr John Wagner. “Achieving criticality in roughly 150 days is a remarkable accomplishment, and Idaho National Laboratory is proud to have provided the facilities and expertise that helped make this milestone possible.”
Deployable Energy’s website says the company was founded in 2025 on a simple idea: nuclear energy should be a product, not a project. “The modern US industrial base is built to manufacture products—repeatable, scalable systems that can be deployed quickly and affordably.… We are building nuclear systems in the same way the energy industry builds everything else – through world-class engineering, manufacturing, and supply chains that already operate on a global scale…. This philosophy drives our technology.”
The UNB uses standard fuels, materials, and industrial processes already available at commercial scale. “The result is a system that can be produced in volume, deployed quickly, and operated reliably across a wide range of applications.” Deployable Energy builds systems that rely on existing supply chains and proven manufacturing techniques. “We avoid exotic materials and specialised components that slow deployment or complicate maintenance…. We don’t need water, heavy site construction, or massive acreage. Nuclear is notoriously expensive and driving down cost informs every decision we make.”
In the spring of 2026, Gallagher decided to bypass traditional, slow-moving heavy freight logistics. To visually and functionally prove that the UNM was a truly mobile product, rather than a sluggish civil engineering project, he loaded the actual reactor core test rig into the back of a standard Ford F-150 and drove it cross-country from Houston, Texas, to the Idaho desert.
By contrast, transporting Valar’s Ward 250 from California to Utah’s San Rafael Energy Lab required three C-17 Globemaster III military transport aircraft.
While DOE support assists with expediting design and development, deployment and grid connection of any new reactor will still require NRC authorisation. Gallagher said his company is likely to apply for a commercial licence for its reactor later this year after a new rule for microreactor licensing is finalised. From there, he expects NRC’s review process to take six to 12 months.
