The US Department of Energy (DOE) has conditionally selected Westinghouse and Radiant to perform the first tests using the Demonstration of Microreactor Experiments (DOME) facility at Idaho National Laboratory (INL). The first-of-a-kind experiments are intended to fast-track the deployment of US microreactor technologies to keep pace with the demand for more abundant, affordable, and reliable power.
The DOME test bed, currently under construction, is repurposing the lab’s Experimental Breeder Reactor-II containment structure to lower the risk of developing microreactor designs capable of producing 20 MWt or less and is on track to receive its first fuelled reactor experiment in early 2026. The facility is operated by DOE’s National Reactor Innovation Center (NRIC).
In 2024, Westinghouse, Radiant, and Ultra Safe Nuclear were selected to receive federal funding totalling $3.9bn to support them in the front-end engineering & experiment design (FEEED) process in preparation for the testing of fuelled reactor experiments at DOME. Data collected from the experiments will be used to commercialise each reactor technology. Westinghouse and Radiant are currently working through the multi-phase DOE authorisation process to support the design, fabrication, construction, and testing of each fuelled reactor experiment.
Westinghouse (Etna, Pennsylvania) will test the eVinci Nuclear Test Reactor to inform the development of its commercial transportable microreactor that uses advanced heat pipe technology to passively cool the reactor. The eVinci reactor is designed to produce 5 MWe on sites as small as two acres of land and could be used to power various applications from remote communities to mining operations or data centres.
Radiant (El Segundo, California) will test the Kaleidos Development Unit to advance the company’s commercial 1.2 MWe high-temperature gas reactor design as a potential replacement for diesel generators. Kaleidos is designed to operate for five years before refuelling and could provide reliable back-up power to facilities such as hospitals and military installations.
“Microreactors will play a big role in expanding the use of nuclear power in the United States,” said Mike Goff, Acting Assistant Secretary for Nuclear Energy. “Thanks to President Trump’s leadership, these DOME experiments will test new reactor designs that will be counted on in the future to reliably power our homes, military bases, and mission critical infrastructure.”
DOE estimates that each DOME reactor experiment will operate up to six months. The testing campaigns are self-funded by the applicants with the sequencing of experiments based on several criteria, including technology readiness, fuel availability, and a regulatory approval plan. Both companies are expected to meet certain milestones throughout the process to maintain their allotted time in DOME and to ensure efficient use of the test bed.
DOE has determined there will be no significant environmental or health impacts related to testing at DOME. DOE recently closed its first round of applications for scheduling experiments in DOME. The next call for applications is anticipated to be in the summer of 2026.
The finding allowed DOE to move forward in scheduling and preparing for its first microreactor test. The decision to issue a Finding of No Significant Impact is based on the final DOME environmental assessment released in May that covers any experiment within the review envelope of the facility, thereby avoiding the need for additional environmental reviews for each individual reactor test.
The assessment also detailed the review and analysis of alternatives considered by DOE based on the National Environmental Policy Act and found that testing in DOME will not adversely affect air quality, water resources, socioeconomics, public and occupational health, safety or transportation.
