The US Department of Energy announced that Antares Nuclear’s Mark-0 advanced reactor successfully reached criticality at Idaho National Laboratory, marking the first privately developed non-light-water reactor to do so in the United States in more than 40 years. The achievement confirms the reactor’s ability to operate safely and supports future commercial deployments that could begin generating electricity as early as 2027.
DOE officials described the milestone as a major step in reviving the US nuclear industry. Developed through the DOE’s Reactor Pilot Program, the Mark-0 demonstration will help advance the design, licensing, and commercialization of next-generation microreactors for civilian, military, and potential space applications.
