Nuclear microreactors have been talked about for decades as potential answers to specific power needs. Designers have made considerable advancements on paper; however, opportunities to demonstrate the capabilities of these designs in practice remain few and far between. A significant gap remains between innovating microreactor technologies and validating them through hands‑on testing.
What has limited microreactor developments
There exists a small but significant niche of advanced nuclear development occupied by microreactors. Generally speaking, microreactors are typically designed to produce up to 20 MW of thermal energy. They are large enough to be built in a factory and shipped; however, they are also large enough to provide power to micro‑grids, remote communities, and other types of locations requiring reliable power.
Despite increasing interest in developing these technologies, developers continue to face challenges in finding a suitable location to test fueled microreactor systems under controlled conditions. Since traditional nuclear facilities are not easily adaptable for experimental reactors, developing a new containment structure solely for testing purposes is both costly and time‑consuming.
As a result, many designs have remained at the conceptual or pre‑demonstrated level longer than their respective developers envisioned. Developing and validating performance, as well as gathering operational data without a dedicated environment to do so, will make advancement toward future licensing and deployment challenging.
Taken together, these constraints have created a development environment where technical ambition has outpaced available infrastructure, leaving promising designs unable to progress beyond early‑stage evaluation.
Purpose‑built pathway from concept to validation
Recognizing this lack of an alternative, the U.S. Department of Energy chose to create an experimental pathway for private microreactor developers. Rather than construct an entirely new facility from scratch, the Department of Energy repurposed an existing containment structure at the Idaho National Lab, which had served as the Experimental Breeder Reactor‑II (EBR‑2).
This resulted in an open‑topped dome‑shaped containment structure measuring 100 ft. in height and 80 ft. in diameter. The containment structure provided a controlled and secure environment to house and experiment with fueled microreactor systems. Developers utilizing the site would no longer need to rely solely on computer simulations or non‑fueled system testing.
Importantly, the site is capable of housing experiments producing up to 20 MW of thermal energy. This corresponds closely with the maximum amount of thermal energy produced by micro‑reactor designs currently under development. As such, the DOME facility is directly applicable to the type of real‑world deployment scenarios for which these types of systems are being developed.
This approach reflects a shift toward enabling demonstration earlier in the development lifecycle, addressing long‑standing barriers without placing the financial burden of infrastructure creation on individual developers.
A milestone marking a change
The testbed, referred to as the Demonstration of Microreactor Experiments (DOME), has recently completed construction and has officially opened for industry usage at Idaho National Laboratory. Designed to support fueled microreactor experimentation at operational scale, DOME marks an inflection point for U.S.‑based developers seeking to move beyond purely conceptual systems.
According to the Department of Energy, DOME was constructed with the intention of reducing development timeframes, decreasing financial risks associated with testing, and accelerating the movement from concept to demonstrated technology. Using an existing containment structure enabled the project to be completed far more quickly than would have been possible with a purpose‑built facility.
Several privately developed microreactor technologies are expected to utilize the testbed, positioning U.S. start‑ups to conduct experiments that were previously impractical or infeasible within the domestic nuclear ecosystem.
For U.S.-based nuclear start-ups, the opening of DOME represents more than new infrastructure; it establishes a direct link between innovation and validation. Access to a nationally funded test environment allows developers to move beyond conceptual designs toward demonstrable technologies within the advanced nuclear ecosystem.
