US Nuclear Startups Hit Critical Milestone, Sparking "Renaissance" Hopes

Three innovative nuclear startups have achieved a significant milestone, reaching criticality in their new reactors as part of a pilot program by the US Department of Energy. This accomplishment, timed around the Fourth of July celebrations, is hailed as a crucial step in "America's nuclear renaissance," an initiative aimed at developing and deploying the next generation of atomic energy. Other companies in the program are also expected to reach criticality soon, following an aggressive deadline set by a presidential executive order. While this achievement is a major public relations boost for the nuclear industry, experts caution that these are still test reactors, not commercial products. Adam Stein, director of the Nuclear Energy Innovation program at the Breakthrough Institute, notes that these prototypes "mean everything and nothing" – significant for the companies involved but far from market-ready. Nevertheless, this rapid progress challenges the long-held perception that new nuclear reactor designs were always a decade away, shifting the narrative and attracting investor interest. The acceleration of these projects is largely attributed to the Trump administration's push to streamline regulations and expedite development, especially for smaller, more innovative reactor designs. Silicon Valley investors and tech figures view these compact reactors, capable of providing 24/7 carbon-free energy for data centers and other operations, as integral to a new technological era. The administration responded with actions including the pilot program, established via an executive order in May 2025, which set an ambitious timeline for at least three reactors to achieve criticality by July 4, coinciding with the nation's 250th anniversary. Beyond regulatory cuts, which saw the Department of Energy quietly slash environmental and safety regulations for reactors under its purview in February, these startups also benefited from substantial support from federally funded national laboratories. Valar Atomics, for instance, reached criticality at Los Alamos National Laboratory, utilizing the lab's structural components alongside its own fuel. Antares Nuclear and Deployable Energy, the other startups meeting the deadline, similarly achieved criticality at national labs, underscoring the collaborative effort to accelerate innovation. However, reaching criticality does not equate to immediate commercial viability or electricity generation for the grid. While Valar's reactor design successfully powered an Nvidia chip in a recent demonstration – a first for an advanced US reactor – most are still in the testing phase. Commercial products face a lengthy licensing process with the Nuclear Regulatory Commission, traditionally taking years, although potential regulatory cuts could shorten this. Furthermore, securing robust supply chains, particularly for specialized fuel, remains a significant hurdle for these companies transitioning from lab prototypes to market-ready solutions. Brett Rampal, senior director of nuclear and power strategy at Veriten, acknowledges the "amazing achievement" of bringing new reactors critical in 2026. Yet, he advises against an overly romanticized view of a new nuclear golden age, emphasizing the persistent financial realities: nuclear plants remain expensive and time-consuming to build. The journey from successful pilot to widespread commercial deployment, therefore, still presents considerable technical, regulatory, and economic challenges.