Trump sits at his desk in the Oval Office with Antares CEO Jordan Bramble, Secretary of Energy Chris Wright, and others standing behind, on July 24, 2026. Four nuclear companies, including Antares, met the administration’s July 4 deadline for achieving reactor criticality under the Reactor Pilot Program. (The White House/Daniel Torok)

The Microreactor Miracle Meets a Morphing AI-Nuclear Future

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The microreactor milestone is real, but shifting AI models, China’s challenge, and deployment delays could complicate America’s nuclear ambitions.

It was impressive that four microreactor start-up companies beat the clock and achieved reactor criticality in compliance with the Trump administration’s arbitrary July 4 Reactor Pilot Program (RPP) deadline. But these reactors are years away from deployment, and the excessive swaggering associated with this modest achievement is out of step with the quavering nuclear energy realities ricocheting off a rapidly evolving artificial intelligence (AI) system.  

US Microreactor Achievements

Of the four reactors that achieved zero power, only Antares has an identified market application beyond this demonstration. Its Mark-1 reactor has been selected as a pilot technology for powering Joint Base San Antonio, Texas.

The Antares Mark-0 reactor, which is the zero-power test reactor and prototype for the commercially oriented R1 Mark1, was the first to meet the criticality deadline on June 4 at Idaho National Laboratory (INL). It uses High Assay Low-Enriched (HALEU) TRistructural isotropic (TRISO) fuel and is sodium-cooled. The projected commercial reactor can provide 100 kilowatts to 1 megawatt (MW) electric power. Beyond its work with the Department of Defense (DOD), Antares also has been working with the National Aeronautics and Space Administration (NASA) on potentially powering a Moon base. 

Valar Atomics’ Ward-250 achieved criticality on June 18 in Utah and claimed it produced 10 kilowatts (kW) of thermal output. It had previously announced a criticality test at Los Alamos National Laboratory in November 2025. The Ward-250 is a TRISO-fueled high-temperature gas reactor (HTGR) that uses helium as a coolant. After the test, Valar announced a partnership with Nvidia to explore powering AI data centers and stated that its evolving commercial unit could be “deployed by the hundreds at ‘gigasites’” that could support manufacturing as well as energy production.

Deployable Energy, a year-old company, met the criticality mark on June 30 at Idaho National........

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