Aalo Atomics achieved a self-sustaining nuclear chain reaction, known as criticality, for its Aalo-X Critical Test Reactor at Idaho National Laboratory on July 4, 2026, marking the first time a new sodium-cooled reactor has operated in the United States in more than four decades.
The test reactor, which produces 10 megawatts of electric power (MWe), uses the same full-scale core components as the company’s planned commercial product, the Aalo Pod. The milestone validates the core design and positions the company to pursue Nuclear Regulatory Commission authorization for commercial deployment.
“The Aalo-X’s 10 MWe reactor design positions it as the premier power provider for the modern data center,” said Matt Loszak, CEO of Aalo Atomics. “Reaching criticality is our most significant milestone to date, as it paves the way for the deployment of the Aalo Pod to power commercial data centers.”
Speed From Founding to Fission
Aalo Atomics was founded less than three years ago and has moved with unusual speed for the nuclear industry, where projects routinely take a decade or longer. The reactor building at Idaho National Laboratory went from a bare dirt field to an operational facility in six months.
The company’s pace exceeded the Trump administration’s stated goal. US Energy Secretary Chris Wright noted that President Trump had called for three advanced reactors to achieve criticality by the 250th anniversary of the nation’s founding. “Through the dedication and hard work of Aalo, INL and DOE, we have surpassed that ask and delivered four,” Wright said.
Fuel rods for the Aalo-X were manufactured by GE Vernova’s Global Nuclear Fuel business and delivered to Idaho in April 2026.
Commercial Plans and Partnerships
The Aalo Pod is designed as a 50 MWe system comprising five sodium-cooled Aalo-1 reactors driving a single turbine. The reactors are air-cooled and require no external water source, a significant advantage for data center deployment in water-stressed regions.
Aalo targets a commercial price of three cents per kilowatt-hour (approximately 2.4 pence), which would be competitive with new natural gas or solar plants.
The company has already begun work on a second reactor at Idaho National Laboratory, named Project Ascension, which will be a commercial-scale system designed to supply power to an on-site data center. Aalo expects the Aalo Pod to be commercially deployable within 18 months, pending NRC authorization.
Aalo has also partnered with Microsoft and Nvidia to develop an automated co-piloting system for managing fleets of nuclear reactors, a sign of the deep integration the company envisions between nuclear power and AI infrastructure.
The company’s Austin, Texas factory, spanning 3,716 square meters (approximately 40,000 square feet), produces reactor modules that are transported to deployment sites for assembly, a manufacturing approach Aalo says will allow it to scale production far faster than conventional nuclear construction.
Sources: US 10-MWe nuclear reactor reaches criticality for commercial data center power (Interesting Engineering, July 6); Aalo Atomics Unveils Critical Test Reactor (Aalo Atomics, March 2026); Aalo Atomics breaks ground on experimental nuclear reactor (Data Center Dynamics, September 2025); US Department of Energy press release (July 2026)