DOE-Backed Small Reactors Reach Criticality at 3 U.S. Startups as Trump Pushes 400-GW Nuclear Goal
Updated
Updated · POLITICO · Jul 1
DOE-Backed Small Reactors Reach Criticality at 3 U.S. Startups as Trump Pushes 400-GW Nuclear Goal
3 articles · Updated · POLITICO · Jul 1
Summary
Three DOE-backed advanced reactors have now reached criticality, with Deployable matching June milestones by Antares and Valar, and Aalo expected to become a fourth before July 4.
DOE sped those demonstrations by opening national labs, approving safety analyses and cutting red tape, part of a broader Trump administration push to expand U.S. nuclear capacity to 400 gigawatts by 2050.
Commercial use is still distant because NRC licensing remains separate, though officials hope DOE-reviewed designs and a proposed fast-track rule could shorten approvals; Deployable expects to seek a license later this year.
Key hurdles remain beyond criticality: no U.S. commercial HALEU supply, questions over whether some microreactors can power large data centers, and financing gaps for multibillion-dollar projects without federal construction funding.
The milestones strengthen nuclear's case as power demand rises from AI data centers, but industry and outside analysts say demonstration success is not yet a commercial breakthrough.
Can small nuclear reactors power the AI boom despite critical fuel shortages and massive funding gaps?
With demonstration reactors now online, what is the true timeline for them to power our data centers and cities?
Can America rebuild its entire nuclear supply chain fast enough to meet its ambitious 2050 energy goals?
Quadrupling U.S. Nuclear Capacity by 2050: Breakthroughs, Policy, and the Race for Advanced Reactor Deployment
Overview
In June 2026, the U.S. advanced nuclear sector reached a major milestone as Antares Nuclear’s Mark-0 microreactor and Valar Atomics’ Ward 250 both achieved criticality, marking rapid progress in next-generation reactor development. These successes were made possible by decades of Department of Energy investment in advanced fuel technology and strong support from Idaho National Laboratory. Valar Atomics’ achievement was further enabled by executive orders that provided a clear mandate and streamlined federal review, including oversight by DOE officials and a joint test group. Together, these breakthroughs highlight the power of coordinated policy, technical innovation, and public-private collaboration in advancing clean energy.