US opens DOME, a first-of-a-kind microreactor test bed

Key facts

• The DOME microreactor test bed is now open at Idaho National Laboratory
• It is built inside the repurposed containment of EBR-II, a sodium-cooled breeder reactor that operated 1964–1994
• Developers can run fuelled experiments in a shared, pre-existing safety envelope instead of building their own facility

Repurposing nuclear history for future innovation

In a significant move to reclaim global leadership in advanced nuclear technology, the United States has officially opened the Demonstration of Microreactor Experiments (DOME) test bed. Located at Idaho National Laboratory, the facility is poised to become a critical catalyst for the rapid development and commercialisation of next-generation microreactors.

The DOME facility is a masterclass in sustainable infrastructure: it is built within the repurposed containment structure of the Experimental Breeder Reactor-II (EBR-II), a pioneering sodium-cooled breeder reactor that operated from 1964 to 1994. Much of the original equipment was removed, but the containment itself — a piece of nuclear history — now shelters the industry's newest machines.

Why a shared test bed changes the economics

Until now, a developer wanting to run a fuelled experiment had to design, licence and build its own facility first — often the single largest cost and schedule item on the path to market. DOME inverts that: the containment, safety case scaffolding and site infrastructure already exist, and experiments cycle through the same proven envelope.

What to watch next

The first experiments are expected to begin loading within the next two years. Watch which developers secure the early slots, because a place in the DOME queue is now one of the clearest signals of which microreactor designs are closest to commercial reality.