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Four nuclear reactors hit a big milestone in the US
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Fusion42 · 10 July 2026 · Fusion42 review
Four US microreactor startups (Antares Nuclear, Valar Atomics, Deployable Energy, Aalo Atomics) achieved criticality—the ability to sustain a nuclear chain reaction—by July 4, 2026, meeting a Trump administration goal. Criticality is a technical milestone but does not mean the reactors are ready to generate grid electricity; companies now face cooling systems, regulatory approval, and significant engineering work before commercial deployment.
This Wire brief sits within Fusion42's coverage of Clean Energy and Energy Storage.
◆ ◆ The Wire takeaway
You've just proved your reactor works at zero power; now you need to cool it, licence it, and actually generate electricity—all before 2027-2028. The regulatory path the NRC promised earlier this year is untested, and your startup timeline is already aggressive; regulatory delays will compress your cash runway harder than any technical problem.
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1 source · 10 Jul 2026
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