Aalo Atomics’ experimental test reactor reached sustained nuclear chain reaction early on July 4 at Idaho National Laboratory, marking the fourth advanced reactor to achieve criticality this year and surpassing a presidential directive that sought minimum approval of three such facilities by the nation’s 250th anniversary.
The Aalo-X Critical Test Reactor attained criticality at 12:20 a.m. Mountain Time on Independence Day, following completion of fuel loading and zero-power demonstration operations. The milestone represents the culmination of an eight-month construction and activation timeline from initial ground-breaking to operational status.
Racing Toward a Nuclear Milestone
Energy Secretary Chris Wright credited the achievement to coordinated effort across multiple organizations. “President Trump asked for three advanced reactors to be authorized and achieve criticality by the 250th anniversary of our great country. I’m pleased to share that through the dedication and hard work of Aalo, INL, and DOE, we have surpassed that ask and delivered four!” Wright stated.
The federal push stems from Executive Order 14301, which directed the Department of Energy to approve deployment of at least three advanced reactors reaching criticality by July 4, 2026. Aalo’s achievement became the fourth to clear that threshold.
Three other companies preceded Aalo to operational status. Antares Nuclear’s Mark-0 reactor achieved criticality on June 4 at INL. Valar Atomics’ Ward 250 reactor reached criticality on June 18 at the Utah San Rafael Energy Lab. Deployable Energy’s Unity reactor attained zero-power criticality on June 30 at INL.
Design and Construction at INL
The Aalo-X represents a 10-megawatt electric design employing low-enriched uranium dioxide fuel with graphite moderation and liquid sodium cooling. The reactor uses a hybrid loop-pool configuration for its primary vessel, with a secondary sodium loop that transfers heat to a steam generator.
Aalo constructed its Critical Test Reactor facility on a two-acre site at Idaho National Laboratory, completing the 60-by-60-by-60-foot structure in eight months from initial excavation to full operational status. The rapid timeline underscores modern construction and engineering capabilities applied to advanced nuclear projects.
Yasir Arafat, Aalo’s president and chief technology officer, framed the reactor’s activation as validation of American technical execution. “The success of the Department of Energy Reactor Pilot Program is proof America can execute again,” Arafat said.
Commercial Deployment on the Horizon
Beyond the research milestone, Aalo has outlined plans to move toward commercial deployment. The company intends to provide its commercial Aalo Pod design to data centers within 18 months, positioning advanced reactor technology for real-world energy applications in computing infrastructure and other industrial uses.
The achievement at INL builds momentum for advanced reactor development across multiple technology approaches. The site has become a national testing ground for next-generation nuclear concepts, with multiple fuel and design validation programs advancing in parallel. Federal leadership has emphasized the strategic importance of these milestones, framing advanced nuclear as central to American energy independence and industrial competitiveness.
Idaho Falls and Bonneville County have positioned themselves as anchors in the national advanced reactor ecosystem, hosting multiple projects and research initiatives under INL’s coordinating role.
What Comes Next
Aalo will transition the Aalo-X from experimental operations toward demonstration of sustained power generation and thermal performance. The company’s 18-month timeline for commercial pod deployment suggests acceleration toward utility-scale applications. Meanwhile, INL continues hosting additional advanced reactor projects from other developers, maintaining its role as the primary federal testing facility for next-generation nuclear technology. Observers expect announcements of additional reactor activations and power demonstrations throughout 2026 and into 2027 as the federal Reactor Pilot Program advances multiple parallel designs toward commercial viability.