Hello, and welcome back to Inc.'s 1 Smart Business Story. Are we on the precipice of a nuclear energy renaissance? Perhaps. But the enormous water-cooled reactors of the last few years are likely to be replaced by smaller, modular versions, SMRs. They produce less energy but they are also safer and less expensive to build. The Microsoft-backed SMR company, TerraPower, recently broke ground on an SMR plant in Wyoming, and there’s a cohort of eager startups close on their heels. As U.S. energy consumption continues to climb, the race is on for sources of clean, abundant energy. The answer may very well be a new generation of nuclear power.

In this article you'll find:

BY CHLOE AIELLO, REPORTER

Ambitious new nuclear power companies, boosted by the deep pockets of tech, are ready to make good on the promise of clean, abundant energy by the 2030s.

U.S. electricity consumption began climbing steadily around 2020 for the first time in roughly two decades, driven by the energy demands of data centers and a surge in domestic manufacturing. With consumption expected to keep rising, nuclear energy is once again emerging as a serious option for abundant, carbon-free power. It is a revival that has been a long time coming. Public enthusiasm for nuclear energy waned in the late 20th century after accidents at Three Mile Island, Chernobyl, and Fukushima left lasting fears about its safety. Now, a new generation of companies believes it can build reactors that put those fears to rest.

“Tech companies are clearly at the front edge of power needs, and their needs also align with the need for steady state, reliable power,” says Mike Laufer, co-founder of Kairos Power, a nuclear energy startup based in Alameda, California. “It’s created an accelerated sense of urgency on the customer side, and a call to action to figure out what’s going to be available, and on what time scales, to be able to meet those power needs.”

While today’s energy demands make a compelling case for new nuclear development, this isn’t the first so-called nuclear renaissance. The only two U.S. reactors built from scratch in the past three decades, at Plant Vogtle in Georgia, show how difficult new nuclear construction can be. Vogtle 3 and 4 came online in 2023 and 2024, but at a cost of more than $35 billion and 15 years of construction, roughly double the initial estimates on both counts.

Kairos Power is just one among a cohort of private companies developing a new generation of nuclear energy reactors designed to be safer, more cost-effective, and faster to build than anything that has come before. TerraPower was founded in 2008 by Microsoft co-founder Bill Gates, who remains among its largest backers. The company has raised over $1 billion from investors, including Gates, South Korea’s SK Inc., and SK Innovation. X-energy, based in Rockville, Maryland, launched in 2009 with backing from Amazon, which anchored a $500 million Series C-1 round in October 2024 alongside a commitment to help deploy more than five gigawatts of new nuclear capacity across the U.S. by 2039. 

These small modular reactors (SMRs) are meant to be faster and less expensive to build. Additionally, several designs incorporate fourth-generation nuclear technology, which is a category of six systems intended to be safer, more sustainable, more reliable, and more economically viable to operate than their predecessors.

Drive west from Knoxville, Tennessee, for about 40 minutes and you’ll find Oak Ridge. Before 1942,  the town was just a handful of small farms along the Clinch River. That changed when government-funded construction crews arrived to build a covert Manhattan Project facility dedicated to enriching uranium for the United States’ growing atomic arsenal. The work remained a secret until the United States dropped atomic bombs on Hiroshima and Nagasaki, killing approximately 100,000 to 200,000 people and ending World War II. 

Now, eight decades later, Oak Ridge is at the center of a new nuclear era focused not on weapons but on energy. Kairos Power, founded by three University of California, Berkeley-trained engineers—Mike Laufer, Edward Blandford, and Per Peterson—is building its Hermes demonstration reactors on a parcel of land it acquired in Oak Ridge in 2021. The company, started in 2016, has received up to $303 million in grant funding through the DOE’s Advanced Reactor Demonstration Program. Where the Manhattan Project facility once enriched uranium for bombs, Kairos is betting that nuclear energy can provide America with clean, abundant energy. 

“Kairos is a mission-driven company, and the mission is very broad and aggressive, which is to enable the world’s transition to clean energy while protecting the environment and improving people’s quality of life,” says Laufer, who is also CEO of Kairos Power.

The most common active fission reactors today are part of an aging cohort of Generation II nuclear reactors, known as light-water reactors because they use water as a coolant and neutron neutralizer. And while many SMRs are also water-cooled, Kairos is taking a different tack. It uses a molten fluoride salt coolant rather than water. The company says the technology is safer because it operates at low pressure and does not boil at high temperatures, eliminating the risk of steam explosions and large-scale radioactive releases. Kairos also claims the salt helps contain radioactive byproducts from the nuclear reaction, a property enhanced by its specialty fuel.

“The salt serves as our backup barrier,” says Laufer. Drawing on experimental data dating back to the 1960s, Kairos developed what it says is a safer, more cost-effective coolant. Its fuel, called Triso, consists of thousands of uranium kernels coated in ceramic and embedded in graphite. One golf ball-size pebble can withstand exceptionally high temperatures and, according to Kairos, produce more energy than four tons of coal.

Kairos has two reactors at Oak Ridge, each in various stages of development. Hermes 1 is a demonstration reactor built to prove the technology works. It recently made history as the first Generation IV non-light-water reactor to receive a construction permit from the Nuclear Regulatory Commission in the United States. The next step, Hermes 2, is designed to supply 50 megawatts of electricity to the grid, with groundbreaking expected this year after Kairos received the necessary permits in 2024. The company says that, eventually, their commercial reactors will generate 75 megawatts each, deployed in pairs and clustered into groups of up to six—the equivalent of a 450-megawatt plant.

In October 2024, Google signed a deal with Kairos to deploy a fleet of reactors totaling 500 megawatts by 2035; a year later, Kairos, Google, and the Tennessee Valley Authority announced a power purchase agreement under which the Hermes 2 plant will deliver up to 50 megawatts to the TVA grid, powering Google’s data centers in Tennessee and Alabama. The deal makes TVA the first U.S. utility to sign a power purchase agreement with an advanced Generation IV reactor.

TerraPower crossed an even bigger threshold on March 4, when the Nuclear Regulatory Commission issued the first federal construction permit for a full commercial-scale advanced nuclear reactor, which will operate as an actual power plant. TerraPower is now cleared to begin building its Natrium plant in Wyoming, backed not only by Gates but also approximately $2 billion in DOE funding, and an additional $650 million investment round that included Nvidia’s venture arm. 

Like Kairos, TerraPower operates at low pressure and uses an unconventional coolant, but instead of molten fluoride salt, Natrium runs on liquid sodium. “By using new coolants like sodium, that’s the game changer,” says TerraPower’s president and CEO, Chris Levesque. “That’s what allows us to have a low-pressure plant, which lends itself to being lighter and cheaper. It allows us to be safer.”

TerraPower is betting on modular construction techniques to drive down costs and shorten timelines. On the customer side, the company struck a deal with Meta to develop up to eight Natrium reactors, with the first two targeted to come online as early as 2032. PacifiCorp, the Warren Buffett-owned Northwest utility, has agreed to purchase power from the first plant in Wyoming. If that reactor performs as planned, Levesque has set an ambitious pace for what comes next. “Two Natrium units per year,” he says, with a goal of deploying as many as 10 reactors annually before the end of the 2030s.

X-energy is taking a different technical approach but shares the same ambition—and they’ve assembled a formidable coalition behind it. Amazon’s Climate Pledge Fund anchored a $500 million Series C-1 round in October 2024, and X-energy subsequently raised an additional $700 million Series D round led by trading firm Jane Street. Its reactor, called the Xe-100, is a high-temperature gas-cooled reactor that uses helium to capture heat and convert water into steam, which then drives a turbine to generate electricity.

Like Kairos, X-energy uses fuel pebbles. Its proprietary version is called Triso-X. Roughly the size of a billiard ball, each pebble contains a uranium kernel wrapped in multiple layers of carbon and silicon carbide, designed to prevent meltdown and contain radioactive byproducts.

“If you start with a reactor that can’t melt down, then you’re able to dramatically simplify the design, because a lot of the complexity around large light-water reactors is in all of the backup and redundant safety systems,” says CEO J. Clay Sell, who spent three years as deputy Energy secretary under President George W. Bush.

First comes safety, then comes modularity. The Xe-100 is an 80 MWe reactor that is designed to be scaled into a “four pack” configuration that generates 320 MWe. The smaller size and simpler design allow the components to be shipped and assembled more easily in a quality-controlled factory environment. The company is also partnering with Dow to build its first four-unit Xe-100 plant on the Texas Gulf Coast.

“We ship the components to the site and assemble them in a period of months, rather than years,” Sell says.

The small size of SMRs can be both an advantage and a drawback, says Brendan Kochunas, assistant professor of nuclear engineering and radiological sciences at the University of Michigan.

Nuclear power has historically been one of the more costly sources of electricity generation, a gap that is widening as the rapid expansion of renewable energy continues to push prices down. Large, conventional nuclear plants have long relied on economies of scale to justify their economics — their construction costs are enormous, but so is their energy output.

SMRs don’t have that advantage. Although they are expected to cost less per-reactor to develop, they also pump out considerably less electricity, Kochunas explains, meaning the power SMRs produce is almost guaranteed to cost more.

“With the smaller reactors, you need to find niche markets where operators can charge a premium for that electricity,” he says. “That premium can be driven by climate goals, or it can be driven by reliability.”

Kairos, TerraPower, and X-energy all say they’ve lined up clients with the exact sort of spending power and electricity needs that justify higher upfront costs in return for longer-term savings. “We’re entering an era that is unlike the previous nuclear era—new players, new technologies, new financing mechanisms, and a posture of readiness from the public that hasn’t existed since the early 1960s,” says X-energy’s Sell.

Enthusiasm from company executives is expected. And while the International Energy Agency notes that SMRs can serve as a “catalyst for change,” they will need the right mix of policies and financing to succeed. In the IEA’s 2025 report, “The Path to a New Era for Nuclear Energy,” the organization maps out several growth scenarios in which SMR capacity climbs to varying levels, boosted by factors like demand from technology companies, streamlined regulation, and reductions in construction costs. Given just the right environment and, crucially, $900 billion worth of cumulative global investment, IEA projects SMRs could generate 190 gigawatts of energy by 2050.

Back in Oak Ridge, where the atomic age began in secrecy, the next chapter is now being written in plain sight. The technology is different, the motives are different, and for the first time in decades, so is the momentum.