A Fresh Dawn for Nuclear Energy

Welcome to Dispatch Energy! While the headlines chase UFC showdowns on the White House South Lawn and the bungled renovations of the Lincoln Memorial Reflecting Pool, the Trump administration is approaching a quieter but far more consequential landmark: reaching “criticality” with prototypes for next‑generation nuclear reactors.  

In the prior year, the Department of Energy launched the Reactor Pilot Program to facilitate the testing of cutting-edge reactor designs. The administration has set an explicit target: to reach criticality with three advanced reactors by July 4, 2026. In the last month, two program‑authorized units—Antares Nuclear’s Mark-0 sodium‑cooled microreactor and Valar Atomics’ Ward-250 high‑temperature gas reactor—reached criticality.

A reactor attains “critical” status when the nuclear fuel inside establishes a self‑sustaining fission chain reaction—meaning that, on average, each fission event triggers another fission event, enabling continuous energy production. Of course, achieving this in the core is only part of the equation: a commercial plant also needs containment structures, a cooling system to moderate the reaction, turbines to convert heat into electricity, control rooms, spent fuel handling, and more. Yet a self‑sustaining fission process in the core is what makes the whole facility operate.

Today’s U.S. commercial reactors all use low‑enriched uranium and light water as coolant. What the Reactor Pilot Program is doing is proving the technical viability of a new generation of reactors with alternative fuels, fuel cycles, coolants, and other innovative traits. Some designs aim to produce hydrogen or serve high‑temperature industrial needs in addition to generating power, while others are intended for propulsion. All of the reactors under consideration are smaller than conventional plants—some, by design, much smaller in scale.

When I wrote about the Reactor Pilot Program for Dispatch Energy in November, I described it as “the latest step in a technological, regulatory, and commercial reshaping of the American nuclear industry.”

This is just the initial phase—the prototype stage—in a longer journey of innovation that we hope will culminate in fully commercial, next‑generation nuclear reactors supplying abundant electricity on power grids worldwide. Yet it marks a meaningful milestone for an industry reintroducing itself after decades of decline, and for an administration that has placed nuclear power in a prominent strategic position.

From an engineering standpoint, there are compelling reasons to think nuclear power could become the cheapest electricity around. Studies by my organization, the Breakthrough Institute, show that nuclear plants today leave the smallest footprint on land and demand the least material over a life cycle when compared with other energy sources. 

Yet, the construction of nuclear facilities became progressively more expensive through the decades. My fellow Dispatch Energy contributor Roger Pielke Jr. recently published a three‑part history of the United States’ commercial nuclear power development—mostly spanning the 1950s through the 1980s. As Pielke explains, the hopeful, transformative energy technology eventually collided with overregulation, entrenched environmental opposition, and managerial missteps within industry.

Meanwhile, technologies like solar panels, natural gas turbines, and electric vehicles have seen prices fall sharply in recent decades thanks to modular designs and mature supply chains and workforces. The United States now hosts thousands of natural gas and solar facilities, and millions of electric cars. In contrast, just 57 operating commercial nuclear reactors exist nationwide. This is a striking efficiency achievement: those 57 plants supply roughly a fifth of the nation’s total electricity. Yet each one was essentially a bespoke megaproject, with tailored design, planning, construction, and regulatory processes. 

That megaproject approach pushed costs upward for many years. Utilities sought relief by increasing reactor sizes, so each plant could generate more electricity, and by steadily improving the capacity factor—the share of time a plant actually produces power. American nuclear plants average about 1,800 megawatts of capacity with a roughly 92 percent capacity factor, whereas many natural gas plants deliver under 500 megawatts with a 40–60 percent capacity factor. Solar and wind figures tend to be even lower on this metric. 

Even with large reactors that minimize land use and material demands while delivering high output, building new plants has become prohibitively expensive. The Vogtle project in Georgia—technically the lone fully developed U.S. nuclear facility in recent decades—fell more than seven years behind schedule and ultimately cost over $30 billion, more than doubling its initial $14 billion estimate. Vogtle was hailed as the front line of a “nuclear renaissance.” Since then, however, U.S. utilities have shown little appetite for fresh nuclear development. 

That stance has shifted recently. A trio of developments over the past few years has altered the calculus for nuclear power in the United States. 

First, perceptions of nuclear energy have evolved among investors and policymakers. While early generations of civilian reactors emerged under the shadow of the Cold War and anti‑nuclear sentiment, today’s climate‑aware decision‑makers view nuclear as an advanced energy technology with zero pollution and no carbon emissions. Nuclear power now enjoys broad appeal across the political spectrum and is, in fact, the only energy technology gaining traction in popularity right now.

Second, the nation is experiencing a rise in electric power demand. Power generation in the U.S. has stagnated since the 1990s as the economy shifted toward knowledge-intensive and service activities. But the surge in AI data centers, vehicle electrification, and related consumer demand means American electricity consumption is climbing again. All of this additional load has to be supplied by someone.

Third, a new class of reactors has emerged. While some demand is met by reviving old plants—Three Mile Island in Pennsylvania and Palisades in Michigan—the broader growth opportunity lies with small, advanced reactors being developed by firms such as Valar, Antares, Kairos, Oklo, X‑Energy, and Terrapower. 

The appeal of these designs is their potential for modularity similar to natural gas and solar plants. While Vogtle’s units each exceed 1,000 megawatts, the Valar and Antares prototypes now reaching criticality are designed for roughly 5 megawatts or less per reactor. Small units should be easier to manufacture and deploy in multiples, enabling ongoing learning, workforce development, and other industrial improvements that could drive down costs over time. 

These “microreactors” also align with the kind of early‑stage demonstration that the Reactor Pilot Program was built to enable. The initial test reactors will provide essential performance data, allowing engineers and developers to refine designs all the way toward commercial reactor projects.

When the program was announced last year, some outlets questioned whether the July 4 deadline could be met. Some skepticism is understandable, given decades of delays and occasional disappointment in nuclear project development.

Equally, many standard anti‑nuclear voices argued against the program’s objectives, with Edwin Lyman of the Union of Concerned Scientists calling it “an attempt to subvert the laws and regulations that govern commercial nuclear power.”

Yet America’s semiquincentennial is near, and two of the three reactors have indeed achieved criticality. And they did so not through lawless action, but through regulatory reform. Over the past decade, Congress, the Trump and Biden administrations, and the Nuclear Regulatory Commission have all enacted a fundamental shift in nuclear policy—reforming licensing pathways for advanced designs, funding new demonstration facilities at national laboratories, and creating incentives for nuclear power in the marketplace. 

And this is not limited to the demonstration prototypes alone. Startups Terrapower and Kairos Power have begun construction on advanced reactor projects that, if completed, will deliver commercial electricity. The federal Energy Dominance Financing office is also exploring loan guarantees for more traditional light‑water reactor projects. 

All of these policy moves may still fall short of a full nuclear renaissance in the decades ahead. Progress will require navigating science, engineering, markets, geopolitics, and public opinion. Yet many pieces are already in place for what my colleague Ted Nordhaus later described as “the most ambitious effort to commercialize new nuclear energy technology since the Eisenhower era’s Atoms for Peace initiative.”

There remains substantial policy and technological uncertainty ahead for advocates and innovators in nuclear. But this is a moment worthy of recognition—not only for its technical achievement but for its place in a longer line of American breakthroughs.