The US Department of Energy announced that Valar Atomics’ Ward 250 advanced reactor achieved zero-power criticality in Utah, marking a major milestone in the US nuclear energy expansion. The reactor is the first DOE-authorized advanced reactor built outside a national laboratory to reach criticality, meaning it can sustain a controlled nuclear chain reaction ahead of full power generation.
The project is part of the DOE’s Reactor Pilot Program, which aims to speed up deployment of advanced nuclear technologies. Officials highlighted earlier program achievements, including the first-ever airlift of a small reactor aboard a US military C-17, as evidence of accelerating innovation.
Ward 250 is the second advanced reactor to reach criticality under the program, following Antares Nuclear’s Mark-0 reactor. DOE leaders described these milestones as part of a broader push to revive US nuclear energy and expand access to reliable, secure power through faster development and testing of next-generation reactor designs.
