The US Department of Energy (DOE) is leading reactor experiments at its upcoming operating dome (Microreactor experiment demonstration) facility, selecting two companies, Westinghouse and Radiant.
Starting early at the Idaho National Laboratory in spring 2026, these tests mark the world’s first fuel microreactor experiment, potentially dramatically accelerating the commercial deployment of nuclear microreactor technology.
The DOE initiative is a signal that the United States is ready to lead the next generation of nuclear energy. As global demand for low-carbon electricity increases, microreactors provide scalable, transportable solutions to deliver reliable energy where and when needed most.
Mike Goff, the proxy secretary for nuclear energy, emphasized the importance of this technology.
“These dome experiments will test new reactor designs that are expected in the future, ensuring that homes, military bases and mission-critical infrastructure are driven.”
Nuclear microreactor explained
Nuclear Microreactors are compact factory built energy systems designed to generate thermal energy of 1-20 megawatts.
It is not their fuel or coolant that sets them apart, but their innovative design philosophy. Each nuclear microreactor is manufactured entirely off-site and is built for transportation, allowing it to be delivered to remote or rapidly changing locations by truck, rail, or air.
Unlike traditional reactors, these systems are self-regulated and use passive safety mechanisms that reduce the risk of overheating or meltdown.
When deployed, it operates autonomously for up to 10 years without refueling, making it ideal for powering off-grid communities, disaster zones, or isolated facilities such as mining work and military bases.
With the flexibility of generating electricity and supplying direct heat, microreactors are also being investigated for their desalination, hydrogen production and integration with renewable microgrids. Their modular design and long core life make them a game changer to distribute clean power.
Westinghouse and Radiant to Pioneer’s first microreactor experiment
Pennsylvania-based Westin House will test the Evinsi nuclear test reactor at the dome. This innovative design uses advanced heat pipe technology for passive cooling and is expected to deliver up to 5 megawatts of power.
Designed to fit within just two acres, Evinci Reactor can enhance critical operations in grid-off-grid areas, from data centers to remote villages.
Meanwhile, California-based radiation will test the Kaleidos development unit, a high-temperature gas-cooled microreactor expected to generate 1.2 megawatts of power.
The Kaleidos is designed as a clean alternative to diesel generators, optimized for emergency backup power, and can serve hospitals, military facilities and other critical infrastructure.
A five-year fuel cycle and compact design provide a reliable solution for essential decarbonization services.
The companies were selected through a competitive process in 2023 and are currently navigating a rigorous, step-by-step DOE permission process to prepare their designs for experimental operations.
Each experiment at the dome is expected to last up to six months, with test campaigns being self-funded and sequenced according to technology preparation, regulatory planning and fuel availability.
Dome: First Test Bed
The dome facility currently under construction at the Idaho National Laboratory represents the world’s first dedicated nuclear microreactor testbed.
Operated by DOE’s National Reactor Innovation Center, Dome leverages world-class research infrastructure to test real-world reactor performance in a safe and controlled environment.
The facility is designed to process microreactors that generate up to 20 megawatts of thermal energy, providing critical data to support commercialization and regulatory certification.
By enabling safe and accelerated testing, the dome removes major barriers to private industry and supports risky investments in next-generation nuclear technology.
DOE officials have already closed the first round of dome scheduling, where the next opportunity is expected in the summer of 2026. As more reactor designs enter the pipeline, the dome is set to become the cornerstone of America’s clean energy strategy.
The future is small, safe and scalable
With climate targets approaching and the need for increased off-grid power for addictions, nuclear microreactors could become an important pillar of the US energy landscape.
The launch of the dome shows a change in the way the country is approaching nuclear power. This will move from large infrastructure projects to agile deployable systems that provide energy security without carbon emissions.
The world is watching as Westinghouse and Radiant prepare for their 2026 experiment. If successful, these tests not only validate the promise of nuclear microreactants, but also position the United States as a global leader in compact, clean and reliable electricity.
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