Three nuclear energy startups — Valar Atomics, Antares Nuclear, and Deployable Energy — reached criticality with test reactors in mid-2025 as part of a Department of Energy (DOE) pilot program. The program operates under an executive order issued by President Donald Trump in May 2025, which set a deadline for at least three reactors to achieve criticality by July 4.

Valar Atomics reached criticality with a reactor at Los Alamos National Laboratory late in 2024. The company then reached criticality with a second reactor at a state-funded lab site in Utah in early July 2025. During a demonstration on July 3, 2025, Valar Atomics' reactor design powered an Nvidia chip. Both Antares Nuclear and Deployable Energy also achieved criticality at national laboratories.

The pilot program aims to develop and deploy the next generation of atomic energy. The DOE reduced environmental and safety regulations for reactors operating under its purview in February 2025. The Nuclear Regulatory Commission is working with the DOE to establish a fast timeline for the commercialization of reactors involved in the pilot program.

Matt Loszak, cofounder and chief executive officer of Aalo Atomics, another company involved in the program, noted the expedited process. "Before, you'd try to get a signature, and maybe it would sit on someone's desk for five weeks. Now, it's like, done the next day, because it's a priority for the nation," Loszak said. Aalo Atomics has not yet reached criticality. Brett Rampal, senior director of nuclear and power strategy at Veriten, described the progress in a statement: "An amazing achievement to bring new reactors critical and deploy new reactor technology in 2026."

Adam Stein, director of the Nuclear Energy Innovation program at the Breakthrough Institute, described the initial reactors as prototypes. "These prototypes mean everything and nothing. They do a lot for the companies reaching criticality, but even for those companies, they're not commercial products. They're test reactors," Stein said. Rampal also commented on previous industry trends, stating, "If you go back and you look at all the nuclear power plants we built throughout the country, on average, they were over cost and over budget."