Full Breakdown
U.S. Advanced Microreactors Reach Criticality Ahead of 2026 Deadline
7/5/2026, 4:46:29 AM
Core Milestone: Three Reactors Hit Criticality
In July 2026, Antares Nuclear’s Mark-0, Valar Atomics’ Ward 250, and Deployable Energy’s Unity reached self-sustaining criticality, meeting the July 4 deadline of President Trump’s 2025 Executive Order 14301.
Policy Background
The 2025 order launched the Reactor Pilot Program and Nuclear Energy Launch Pad, linking DOE, the National Reactor Innovation Center, and the Fuel Line Pilot Program to accelerate design, testing and fuel supply while letting startups skip the standard NRC review for initial units.
Designs and Performance
Mark-0 is a sodium-cooled, high-temperature reactor with TRISO fuel and passive heat-pipe cooling. Ward 250 is a 100 kWt helium-cooled HTGR designed to scale toward ~5 MW electric. Unity is a 1 MWe gas-cooled microreactor with an actively cooled helium loop, built for factory fabrication and container shipment. Unity achieved criticality in ~150 days; Ward 250 reached 10 kW thermal within days; Mark-0 supports high-temperature operation for forward-operating-base use.
Timeline
June 4, 2026 – Mark-0 critical at Idaho National Laboratory.
June 18 – Ward 250 critical in Emery County, Utah.
July 1 – Unity zero-power critical at INL’s Hot Fuel Examination Facility (?150 days).
July 2 – DOE confirmed the three-reactor milestone.
Official Statements
DOE Secretary Chris Wright said the milestone showed the government could accelerate advanced nuclear development and stressed its importance for energy security. Deployable Energy CEO Bobby Gallagher thanked the administration for an audacious goal and praised DOE and INL for rapid execution. Antares CEO Jordan Bramble warned that nuclear development in the United States has been hampered by long delays. INL Director John Wagner described the 150-day timeline as remarkable.
Criticism & Challenges
Analysts note microreactors cannot yet meet AI-driven data-center power needs, which may require gigawatt-scale supply. Supply-chain limits for high-assay low-enriched uranium and an 18-12-month NRC licensing window add hurdles. Veriten’s Brett Rampal warned historic nuclear projects have been “over cost and over budget.”
Conflicting Reports & Gaps
Sources differ on Ward 250’s rating: one lists a 100 kWt thermal core, another cites a design goal of roughly five MW electric. Unity’s NRC licensing timeline is only described as a projected six-to-12-month review, with no firm date.
Verbatim Quotes
- “ Secretary Wright continued, “We accomplished a significant milestone on a timeline many thought was unachievable.” — Chris Wright, U.S. Secretary of Energy
- “The result is a system that can be produced in volume, deployed quickly, and operated reliably across a wide range of applications.” — Bobby Gallagher, Co-Founder & CEO, Deployable Energy
- “Nuclear in America has been defined for too long by delays.” — Jordan Bramble, CEO, Antares Nuclear
- “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.” — John Wagner, Director, Idaho National Laboratory
What's Next
Deployable Energy plans to file a commercial license application later in 2026 after the microreactor licensing rule is finalized. Antares aims for electricity generation by 2027 and military deployment by 2028. Valar will continue power-ascension testing. The DOE’s target of 400 GW nuclear capacity by 2050 will require scaling beyond these pilot projects.
