Idaho National Laboratory’s DOME Microreactor Test Facility Officially Opens for Business in Idaho
IDAHO FALLS, Idaho — Idaho National Laboratory announced Wednesday that the National Reactor Innovation Center’s Demonstration of Microreactor Experiments facility — known as DOME — is now officially “open for business,” marking a significant milestone for domestic nuclear energy development and positioning Idaho at the forefront of next-generation reactor technology.
The opening of DOME means microreactor developers from both the private sector and government agencies can now move forward with testing, demonstrating, and validating their reactor designs at the INL campus in eastern Idaho.
A Historic Facility Repurposed for the Future
DOME’s origins trace back to one of nuclear energy’s most storied chapters. The facility repurposes the distinctive dome structure of the Experimental Breeder Reactor-II, known as EBR-II — a 20-megawatt electric reactor that began operation at INL, then known as Argonne West, in 1964 and operated for three decades before shutting down in 1994. That historic dome now serves as containment for a new generation of reactor demonstrations.
According to INL, DOME is designed to host reactors rated at up to 20 megawatts thermal, using fuels with uranium enriched to less than 20 percent U-235. INL noted that other reactor designs and fuel types may also be considered if their design analyses fall within DOME’s established safety parameters.
The legal foundation for DOME was laid years earlier. In 2017, the Nuclear Energy Innovation Capabilities Act was signed into law, authorizing the creation of the National Reactor Innovation Center — envisioned as a program to enable the testing and demonstration of reactor concepts proposed and funded, in whole or in part, by the private sector. Public discussions around DOME specifically began in late 2022 and early 2023, with applications to test at the facility opening in May 2025.
Rian Bahran, the Department of Energy’s deputy assistant secretary for nuclear reactors, described DOME as “essential infrastructure” and called it “a testament to our commitment to a robust nuclear future” and a key tool for “accelerating the development and deployment” of new energy technologies.
Radiant Industries Slated for DOME’s First Fueled Experiment
NRIC is already preparing for DOME’s inaugural fueled experiment, which is scheduled to take place later this year. The first reactor to be tested will be Radiant Industries’ Kaleidos Demonstration Unit, a 1-megawatt microreactor that is TRISO fueled and helium cooled.
NRIC first awarded funding to Radiant Industries — along with Westinghouse and the now-defunct Ultra Safe Nuclear — to develop an experiment for DOME back in 2023. In 2024, Radiant raised $100 million in private funding, directed primarily toward completing its microreactor ahead of the scheduled test. The company’s progress at INL has been closely watched; Antares has also been moving closer to a criticality test of its own microreactor at INL, reflecting the growing pipeline of advanced reactor projects taking shape in eastern Idaho.
NRIC Director Brad Tomer emphasized the broader significance of DOME’s opening for the entire nuclear industry. “With the information gathered from their testing at DOME, reactor developers will turn pioneering ideas into validated technologies to advance nuclear energy,” Tomer said. “We are extremely proud to offer this capability and cannot wait to see the impact it has on the nuclear industry.”
For Idaho, the opening of DOME reinforces INL’s standing as a world-class hub for nuclear research and development, supporting high-paying technical jobs and strengthening the case for nuclear energy as a reliable, emissions-free contributor to American energy independence. Coverage of related statewide energy developments is available at Idaho News.
What Comes Next
With DOME now officially operational, attention turns to Radiant Industries’ Kaleidos Demonstration Unit and its planned fueled experiment later in 2026 — a test that could serve as a model for future microreactor deployments across the country. Both private companies and government agencies that have applied for testing slots at DOME will be responsible for covering the costs of their respective experiments. INL has not announced a public timeline for subsequent experiments beyond the Radiant test, but the facility is now accepting the reactor development community’s full attention as the race to commercialize microreactor technology accelerates.