A Cold War-era nuclear facility at Idaho National Laboratory has completed a major renovation to become the first dedicated testing center in the United States for fueled microreactors, laboratory officials announced.
The Experimental Breeder Reactor-II dome in Arco, a 100-foot structure that housed experimental reactor operations during the 1960s, has been retrofitted with modern safety systems and testing infrastructure to support private-sector development of next-generation nuclear technology.
Accelerated Construction Timeline
Brady Orchard, project director at INL’s Materials and Fuels Complex, said renovation teams completed the work a full year ahead of schedule to address growing industry demand for advanced nuclear energy capabilities. More than 300 workers from the complex and partner construction firms contributed to the project, which involved accelerated procurement timelines with industry collaborators.
The facility now features heavily shielded testing chambers where companies can run operational trials of microreactor prototypes under controlled conditions. Curtis Neilson, technical program manager for the dome project, said the site will allow developers to gather experimental performance data required for federal licensing and eventual commercial deployment of reactor designs.
Economic Impact on Southeast Idaho
Brett Tomer, director of the National Reactor Innovation Center, said the facility is already attracting businesses to the region. At least five companies working with the testing program have opened offices in Idaho Falls, bringing employees and operations to Southeast Idaho as they advance microreactor technologies.
Tomer described the economic benefit as significant for local communities, with multiple reactor developers establishing a physical presence in the area to support their work at the national laboratory.
Strategic Role in Nuclear Competition
Program advocates say the United States is competing internationally to develop deployable microreactors for applications including remote military installations, disaster-response infrastructure, and communities without grid access. The testing facility is intended to accelerate domestic development of reactors that can operate independently of traditional power infrastructure.
Despite extensive modernization, the facility preserves a piece of its original mission. The 1960s-era control room from the Experimental Breeder Reactor-II remains intact as a heritage element within the renovated structure.
What Comes Next
Idaho National Laboratory plans to begin supporting the first reactor demonstration projects at the facility this summer. The timeline would make it one of the first operational testing environments in the nation for companies advancing microreactor concepts toward commercial viability.
The Arco site joins a network of INL facilities supporting advanced reactor research across Bannock County and the broader Idaho Falls region, where federal nuclear programs have driven economic activity for decades.