Idaho National Laboratory opens DOME test bed for microreactor experiments

Idaho National Laboratory opened DOME as the first U.S. microreactor test bed, giving private advanced reactor developers something the sector has lacked for years: a place to run fueled experiments instead of leaning on paper studies and indirect validation. The facility is meant to shorten the grind from concept to license application, and that is the real story here. If DOME works the way Idaho National Laboratory and the Department of Energy say it should, it removes one of the biggest commercialization bottlenecks in advanced nuclear.

The test bed sits inside the repurposed containment structure from Experimental Breeder Reactor-II at Idaho National Laboratory in Idaho Falls, Idaho. It is a physical reset of old nuclear hardware for a new market, with the structure itself described as about 80 feet in diameter and 100 feet tall. DOE says DOME can host fueled reactor experiments up to 20 megawatts thermal, enough to generate the kind of operating data developers need before they ever ask a regulator to bless a commercial design.

That matters because the industry has spent years talking about microreactors as the next step in advanced nuclear while still struggling to prove hardware, fuels and operating behavior under realistic conditions. DOME is designed as a hands-on demonstration pathway for industry, and DOE says each testing campaign will be self-funded by the applicant. Test sequencing will depend on technology readiness, fuel availability, procurement scheduling and a regulatory approval plan, which is exactly the kind of practical gating that separates real deployment from PowerPoint optimism.

The schedule has already moved in phases. Idaho National Laboratory previously said the first fueled reactor experiment could begin as early as spring 2026. DOE later said the first experimental reactor would be received in fall 2026, with testing likely to begin in 2027. That next step will be the proof point that matters most: not the opening itself, but whether a private developer actually wheels in fuel, starts a campaign and produces data useful for a future licensing package.

DOE has described DOME as the world’s first microreactor test bed and part of an effort to reinvigorate the American nuclear energy industry. INL and the National Reactor Innovation Center have framed it as a way to move innovators from concept to demonstration faster than the industry has seen in decades. After years of advanced reactor promises, DOME gives the sector something concrete: a national-lab venue where the distance between design and deployment just got a lot shorter.