Three nuclear startups have achieved a key technical milestone as part of a Department of Energy pilot program designed to accelerate the next generation of atomic energy. Valar Atomics, Antares Nuclear, and Deployable Energy all reached criticality—sustaining a nuclear chain reaction—ahead of a July 4 deadline set by President Donald Trump in an executive order last year. The achievement is being touted by Energy Secretary Chris Wright as part of "America's nuclear renaissance," but industry experts urge caution about what the milestone actually means for the commercial viability of small modular reactors.
The Milestone
The executive order, issued in May 2025, set an aggressive timeline for at least three reactors to reach criticality by July 4, 2026, coinciding with the country's 250th anniversary celebrations. According to Molly Taft of WIRED, three startups met that deadline: Valar Atomics, Antares Nuclear, and Deployable Energy. Valar Atomics first reached criticality late last year at Los Alamos National Laboratory, using a core with its fuel and key structural components provided by the lab. It reached criticality again with a second reactor at a state-funded lab site in Utah earlier this month. A fourth company, Aalo Atomics, is part of the pilot and expects to hit criticality soon, according to cofounder and CEO Matt Loszak.
Why It Matters
For decades, the American nuclear landscape has been dominated by large light-water reactors. Smaller, more innovative designs have remained elusive due to slow regulation and high upfront costs. Adam Stein, director of the Nuclear Energy Innovation program at the Breakthrough Institute, said the pilot program "changes the narrative" by showing that new designs can move faster if intentionally accelerated. "That means a lot for the investment community," Stein said. The Trump administration has also slashed environmental and safety regulations for reactors under DOE purview, including those in the pilot program, creating "significant time savings" for companies, according to Stein. Similar regulatory cuts are being worked out at the Nuclear Regulatory Commission for commercially sold reactors. Tech investors and Silicon Valley figures increasingly see smaller reactors as a source of 24/7 carbon-free energy for data centers and other operations.
Why It Doesn't
Despite the progress, Stein emphasized that "these prototypes mean everything and nothing." He noted, "They do a lot for the companies reaching criticality, but even for those companies, they're not commercial products. They're test reactors." The pilot program relied heavily on federal laboratories and regulatory exemptions that may not apply to commercial deployments. The path to a commercially viable reactor still faces regulatory, financial, and technical hurdles. As Stein put it, "The industry has long been viewed as stuck—a nuclear reactor was always 10 years away." Reaching criticality does not guarantee that these designs can be built at scale or licensed by the NRC for wider use.
Companies and Status
| Company | Status | Location | Notes |
|---|---|---|---|
| Valar Atomics | Criticality reached late 2025 and again early 2026 | Los Alamos National Laboratory (NM); state lab in Utah | First reactor used lab-provided core and components |
| Antares Nuclear | Criticality reached by July 4, 2026 | National lab (unspecified) | Part of DOE pilot |
| Deployable Energy | Criticality reached by July 4, 2026 | National lab (unspecified) | Part of DOE pilot |
| Aalo Atomics | Expected soon | Not specified | Cofounder Matt Loszak credits government prioritization for speed |
Outlook
While the milestone is a public relations victory for the nuclear industry, experts caution that commercial reality remains distant. The DOE pilot program and regulatory cuts have accelerated development for these few startups, but the broader industry still faces an uphill battle. As Stein concluded, the prototypes change perception but are not yet ready to power the grid. For enterprise technology leaders eyeing nuclear as a clean energy source for data centers or operations, the lesson is that progress is real but still incremental.
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