U.S. Small Modular Reactors Hit Criticality Ahead of Independence Day Goal

Antares Nuclear reached criticality on June 4, 2026, at Idaho National Laboratory, and Valar Atomics did so on June 18, 2026, in Utah. Both meet President Donald Trump’s July 4, 2026, target for three experimental reactors under the DOE’s Reactor Pilot Program. Radiant Nuclear is testing a DOME-encased reactor at INL but does not expect criticality by the deadline.

In Idaho, the next generation of US nuclear reactors nears reality

In early 2025, President Trump ordered the DOE to help private firms build at least three experimental reactors by the nation’s 250th anniversary. The DOE launched the Reactor Pilot Program, rewriting safety and security standards, streamlining licensing, and exempting pilot reactors from environmental review. Officials say the changes are “unnecessary” to alter and that safety is unchanged; critics disagree.

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Energy Secretary Chris Wright said the program will deliver hundreds of reactors by decade’s end, with some producing electricity as early as next year. DOE officials maintain that the revised safety standards have not compromised safety. Antares CEO Jordan Bramble called the criticality milestone a turning point for a new nuclear renaissance.

In Idaho, the next generation of US nuclear reactors nears reality

Edwin Lyman of the Union of Concerned Scientists warned the rapid deregulation “takes us back to the 1950s” and could erode security and environmental standards, noting that criticality alone does not ensure a stable, commercial power plant.

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• “This is taking us back to the 1950s, and that is not progress,” — Edwin Lyman, Director, Union of Concerned Scientists

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• “This is the first real moment in this new nuclear renaissance,” — Jordan Bramble, CEO, Antares Nuclear

In Idaho, the next generation of US nuclear reactors nears reality

• “The whole plant can get simpler. We don't need to have several feet thick of concrete and steel line containment,” — Yasir Arafat, President & CTO, Aalo Atomics

In Idaho, the next generation of US nuclear reactors nears reality

• “We'll have hundreds by the end of the decade. In fact, our aggressive goal is we will have some of these reactors producing electricity for beneficial use next year,” — Chris Wright, U.S. Secretary of Energy

In Idaho, the next generation of US nuclear reactors nears reality

DOE officials assert the regulatory changes have not compromised safety, while Lyman argues the opposite. Radiant’s Baranwal says testing will begin but does not expect criticality by July 4, unlike Antares and Valar. The reactors run under a government waiver but still need NRC approval before commercial electricity generation.

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The next phase will focus on NRC licensing, scaling mass production at Radiant’s new factory, and deploying SMRs to U.S. military sites, data centers, and export markets. Stakeholders expect the first electricity-producing SMRs by 2027, pending regulatory clearance and proven safety.

In Idaho, the next generation of US nuclear reactors nears reality