4 Test Reactors Fire Up in Idaho, Boosting Nuclear's $0 Carbon Promise

As the world races to slash carbon emissions, a breakthrough in the Idaho desert is proving that next-generation nuclear can move from concept to reality. For climate advocates who see advanced reactors as an essential complement to wind and solar, the wave of test startups at INL this summer offers tangible hope that firm, zero-carbon electricity is within reach.

In the remote high desert of Idaho, a quiet milestone with profound implications for the world's energy future has been reached. Deployable Energy, a startup operating at the storied Idaho National Laboratory (INL), took its test reactor 'critical' – achieving a self-sustaining nuclear chain reaction for the first time. The achievement signals that a new generation of small, advanced nuclear reactors is moving from design to reality, just as three other companies at INL and one in central Utah also switched on new reactor types this summer. This flurry of activity, on federal land dotted with sagebrush and home to an Atomic City bar of just 52 residents, marks a potentially decisive turn in the decades-long effort to revive nuclear power as a pillar of a low-carbon future.

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Deployable Energy, a startup operating at the storied Idaho National Laboratory (INL), took its test reactor 'critical' – achieving a self-sustaining nuclear chain reaction for the first time.

INL’s legacy stretches back to 1949, when it became America’s testing ground for nuclear technology. Over 900 square miles – roughly the size of Rhode Island – the site has witnessed both triumphs and stigmas. Yet for years, nuclear power stalled; high costs, safety fears, and waste concerns froze new builds in the West. Now, a confluence of factors has reignited momentum. A new presidential administration fast-tracked projects, cutting red tape that had long mired reactor proposals. The result is a 2026 summer where advanced reactor designs are finally being proven outside computer models.

Lance Maul, Deployable Energy’s chief operating officer, called the moment a 'real turning point for the energy future.' Indeed, these small modular reactors (SMRs) and microreactors promise to solve multiple pain points of traditional nuclear. They are designed to be factory-built, cheaper to construct, safer through passive cooling systems, and flexible enough to complement variable renewables like wind and solar by providing firm, carbon-free baseload. For a world struggling to meet climate targets, nuclear’s 24/7 clean energy output is an attractive complement to intermittent sources.

The climate implications are staggering. Current global energy models suggest that keeping warming below 1.5°C will require not only a massive expansion of renewables but also a doubling or tripling of nuclear capacity by mid-century. The fresh wave of testing at INL directly addresses the bottleneck of commercial demonstration – the essential step that derailed previous 'nuclear renaissance' hopes. If Deployable Energy and its peers can move from criticality to grid-connected electricity within a few years, they could unlock a pipeline of orders from utilities and industrial users keen to decarbonize without sacrificing reliability.