Nuclear energy could undergo a renaissance. Here’s what to know.

Senior Science and Economics Correspondent
Illustration by Nadya Nickels.
So much innovation is happening in the nuclear industry right now  in the kinds and sizes of reactors being developed and in the way their construction is being planned. I also see fresh optimism about new ways nuclear power can be instrumental in decarbonizing global economies. At the same time, the nuclear industry must show it is up to the challenge. The sector has been plagued by an inability to get new reactors stood up anywhere close to on time or budget. There’s a lot at stake right now, and as a reporter, it’s a fascinating time to be covering the story. — Cat Clifford

The exploding global demand for energy, combined with the urgent race to reduce carbon emissions, is focusing interest and investment on the once-staid, long-stagnant nuclear industry.

A promising lineup of advanced nuclear reactor technologies and more streamlined and flexible construction techniques are getting public and private funding as nuclear is increasingly seen as a critical piece of the decarbonization puzzle.

“In order to get to our climate goals, we actually absolutely must deploy nuclear, because otherwise the only solutions left to some of those applications will be fossil solutions — natural gas, backup diesel generators,” Kathryn Huff, former assistant secretary for nuclear at the U.S. Energy Department and now a professor at the University of Illinois Urbana-Champaign, told Cipher. “We will never get to net zero without that kind of 24-7 power that nuclear provides for some of those applications.”

Indeed, in the United States, nuclear energy’s importance is the rare point in energy policy with bipartisan agreement. Both chambers of Congress have supported the development of advanced nuclear reactors and passed a pro-nuclear law earlier this year. Abroad, Russia and China have also been investing in advanced reactors.

But the enthusiasm for nuclear technology has its critics. Technology, funding, regulation and even geopolitical concerns are at play — making it unclear if next-generation nuclear will get built fast enough and at sufficient scale to have a meaningful impact in the near-term.

Nuclear’s appeal

Unlike wind and solar, which only produce power when the wind is blowing and the sun is shining, nuclear plants run 24 hours a day, seven days a week. They also generate electricity without producing greenhouse gas emissions, making them an appealing alternative to natural gas and coal power plants as a clean source of always-on power.

Nuclear reactors units one through four at the Vogtle power plant

Four nuclear reactors at the Vogtle power plant in Georgia. The third and fourth reactors are the most recent additions to the U.S. nuclear fleet, which currently has 94 reactors across the country. Photo credit: Georgia Power Company.

That kind of reliability is needed. The U.S. is projected to consume a record 4.1 trillion kilowatt-hours of electricity in 2024, up 3% from last year, according to the U.S. Energy Information Administration.

While ultra cheap renewables, batteries and other energy storage technologies will play a crucial role in weaning the world off fossil fuels, many industry leaders argue we cannot meet the massive scale of our energy needs and decarbonize without nuclear. It is well-suited for manufacturing, hydrogen production, replacing fossil fuels in industrial processes and more.

Recently, nuclear has been singled out as an ideal match for providing the electricity needed to support energy-hungry data centers that power artificial intelligence, for example. By 2030, data centers alone could consume as much as 9.1% of annual U.S. electricity, up from about 4% today, according to non-profit research firm EPRI.

“It’s very expensive to own a data center,” Huff said. “It is even more expensive to own a data center that’s only running at 70% time.”

Some large utilities are taking a fresh look at beefing up their nuclear generation as well, including Dominion Energy and Constellation Energy, although final implementation will take time due to many economic, commercial, operational and regulatory factors.

An artist rendering of Oklo's micro reactor being used to power a datacenter.

An artist rendering of an Oklo reactor powering data centers, seen off to the back right in this picture. “We had a sense” that AI was going to be “a significant driver” for nuclear energy, Oklo’s CEO Jacob DeWitte told Cipher. “We did not appreciate, though, how much and how fast. It’s been kind of crazy to see that, actually.” Image credit: Gensler.

Steel in the ground

Despite predictions for a nuclear renaissance, the future is still uncertain. Of particular concern: nuclear is and has been historically expensive.

In November, nuclear startup NuScale announced it had pulled the plug on a project it planned to build in Utah that would’ve provided power to local community-owned public utilities. The utilities were concerned about taking on the risks of a first-of-a-kind nuclear project and the soaring cost of building the plants made the energy too expensive.

“Launching a first-of-a-kind product requires courage and public-sector support,” Marcus Nichol, executive director of new nuclear at the Nuclear Energy Institute, told Cipher.

Nichol commended Congress and the Biden Administration for their support of new nuclear to help bring costs down, which he said, “is a testament to their commitment to getting these technologies deployed.”

In early July, President Biden signed the ADVANCE Act into law, designed to support development of advanced nuclear reactors by, among other actions, directing the industry’s top watchdog, the Nuclear Regulatory Commission, to reduce license application fees and bolster staffing to speed up reviews. Other examples include $2.5 billion to support advanced reactor development via the 2021 Bipartisan Infrastructure Law and $700 million to develop a fuel supply for advanced reactors from the 2022 Inflation Reduction Act.

“We’ve had a lot of strong bipartisan support. Budgets have been phenomenal,” Michael Goff, the acting assistant secretary for the Energy Department’s Office of Nuclear Energy, told Cipher.

“We have the most resources that I’ve ever seen … on advanced nuclear right now,” he said.

Artist rendering of TerraPower's Wyoming Natrium project.

This is an artist rendering of TerraPower’s Natrium power plant, which it is constructing as part of the Advanced Reactor Demonstration Project, a public-private partnership with the U.S. Energy Department. Photo credit: TerraPower.

Skepticism and concerns

Not everyone agrees federal money should go toward nuclear, however.

David Schlissel, the director of resource planning at the Institute for Energy Economics and Financial Analysis, a non-profit energy finance research organization, published a paper in May arguing that investing in nuclear, given its long development time, is less responsible right now than investing in renewables, which are cheaper and faster to build.

“The Department of Energy has … wasted tens of billions of dollars of taxpayer money” supporting nuclear, Schlissel told Cipher, although he believes it makes sense to do research on nuclear for the future.

The risk of public resistance to nuclear projects in their communities and concern over where and how to permanently store radioactive waste also persists.

The tide of public acceptance of nuclear power may be changing. In 2023, 57% of Americans report being supportive of more nuclear power plants, up from 43% of survey respondents in 2020, according to the Pew Research Center.

However, Schlissel said people may be more open to nuclear energy in the abstract than they are to having it be their neighbor. A possible key flashpoint: no permanent repository for nuclear waste exists in the U.S.

“Do you think people are going to want nuclear waste co-located in their communities?” Schlissel asked. Even if the U.S. identifies a centralized place to store spent nuclear fuel, there could be pushback. “How do you think people in small towns are going to feel about having the trucks trucking radioactive waste, like garbage trucks, going through their streets?” Schlissel asked. They are “not going like that,” he said.

There are significant hurdles for the U.S. nuclear industry to overcome financially, politically and even logistically (like how to store nuclear waste). There are also looming geopolitical risks, nuclear experts warn.

For example, if the U.S. does not establish itself as a global leader in new nuclear technologies, said Chris Levesque, CEO of TerraPower, countries such as Russia, China and France could fill in the gap with their state-owned and heavily-subsidized companies.

“We’re in an international competition,” he said.

What to know about new nuclear technologies

The nuclear industry is attempting to reinvent itself.

Historically, nuclear power plants have been massive, one-of-a-kind complexes that take years to build and supply power to thousands of people. But this model may not work to meet the planet’s future energy needs.

“If I can only buy your product in the Big Gulp size, and I only want a teacup, I’m kind of stuck,” Matthew Crozat, the executive director of strategy and policy development at the industry group Nuclear Energy Institute (NEI), told Cipher recently at NEI’s headquarters in Washington, D.C.

That message has become a prime mover in the race to decarbonize the world’s power supply. To meet growing demand for clean, always-on energy, companies and governments are developing innovative nuclear plants that come in smaller sizes and use more advanced, and potentially safer, technologies.

New uses mean new sizes

The current nuclear fleet in the United States is comprised of 94 reactors that can generate anywhere from 500 megawatts to one gigawatt of electricity. A gigawatt reactor can power one million homes at a time, according to the Nuclear Innovation Alliance.

Nuclear reactor unit 3 at the Vogtle power plant in Georgia

Nuclear reactor unit 3 at the Vogtle power plant went into operation in July 2023, and reactor unit 4 started up in April 2024. Each reactor will provide electricity to approximately 500,000 homes and businesses, according to Georgia Power. Photo credit: Georgia Power Company.

Companies and governments all over the world are working to scale that down, developing reactors in three smaller sizes known as medium, small and micro reactors that generate approximately 300 to 600 megawatts of electricity, 50 to 300 megawatts and less than 50 megawatts, respectively, according to the Idaho National Laboratory. That said, the size definitions for each category vary depending on who you ask.

Medium-sized reactors are well suited to replace aging fossil fuel plants because they aren’t as expensive and don’t take as much time to build as conventional, full-size reactors. They can fit into the existing footprint of a fossil fuel plant and can utilize existing transmission infrastructure, which is in desperately short supply in the U.S.

TerraPower, for example, is developing a 345-megawatt nuclear reactor that could scale up its output to 500 megawatts for up to five hours, said president and CEO Chris Levesque. At its ramped-up level, that’s enough electricity to power approximately 400,000 homes. (TerraPower was founded by Bill Gates, who also founded Breakthrough Energy, which supports Cipher).

“We think there’s a lot of opportunity in that 300-to-500-megawatt region because of retiring coal plants,” Levesque told Cipher. In June, TerraPower broke ground on its Natrium demonstration plant in Kemmerer, Wyoming, which is being built next to a former coal plant.

Photo of TerraPower groundbreaking in Wyoming.

Government and company representatives break ground on TerraPower’s Natrium advanced reactor in Wyoming in June 2024. From L to R: Brian Smith, deputy assistant secretary for nuclear reactors at the U.S. Energy Department; Craig Albert, president and chief operating officer of Bechtel Group; Mark Gordon, governor of Wyoming; Bill Gates, founder of TerraPower and Breakthrough Energy; Chris Levesque, CEO of TerraPower; Cindy Crane, CEO of Pacificorp; Dick Garlish, president of Rocky Mountain Power. Photo credit: TerraPower.

The existing fleet of nuclear reactors “have not seen true innovation in decades, really,” said Levesque, who said he “grew up in the nuclear industry,” previously working in the U.S. Navy as well as at electric company Westinghouse and nuclear company Orano. “Our culture … was always about repeating past performance and maybe making small improvements, but not changing anything.”

That culture is evolving, though, even at legacy companies like Westinghouse, which has been in the electricity game for 130 years and in commercial nuclear for 60 years.

Last year, Westinghouse announced plans to develop a 300-megawatt reactor capable of powering approximately 300,000 homes. It will be a scaled-down replica of Westinghouse’s large AP1000 reactor, two of which were recently installed in Georgia at the newly opened Vogtle power plant (which had massive cost over-runs and delays). The goal is to start building the first of these smaller reactors around 2030.

To meet other needs, some companies are developing even smaller reactors.

Oklo, a nuclear fission company chaired by Sam Altman, CEO of the artificial intelligence company OpenAI, is developing reactors that will produce between 15 and 50 megawatts of electric power, a size well-suited to meeting the needs of individual factories or data centers. Oklo’s reactors will also be poised to provide high-temperature heat for industrial processes, another critical area where nuclear reactors could replace burning fossil fuels.

An artist rendering of the Aurora powerhouse where an Oklo reactor will live.

Artist rendering of the Aurora powerhouse by advanced nuclear reactor company Oklo. Once built, the company’s fast reactors could be able to operate for as long as a decade before needing to be refueled. Image credit: Gensler.

Oklo aims to have its first commercial reactor operating in 2027, according to a company spokesperson.

Another reactor company, Washington, D.C.-based Last Energy, is researching possible military applications for its micro-reactors, in addition to targeting data centers and industrial manufacturers.

New construction, new description

Downsizing is not the only innovation in the nuclear world.

The latest nuclear reactors are often described as “modular,” a reference to how — and how fast — they are built, using parts that can be replicated in a factory, as opposed to bespoke pieces that must be crafted individually.

On its website, Last Energy describes its whole micro-reactor plant as being constructed “much like a LEGO kit,” which includes standardized parts that can be transported and assembled in four months, Matt Fossen, director of public relations for Last Energy, tells Cipher.

Last Energy aims to have its first reactor-plant combination delivered to a customer in 2026.

“We can do more factory construction, less construction on site, and hopefully shorten the overall construction time,” Michael Goff, acting assistant secretary for the U.S. Energy Department’s Office of Nuclear Energy, told Cipher.

Photo of the Last Energy microreactor being displayed in Houston at CERA Week.

Last Energy brought a prototype of its microreactor to Houston for CERAWeek in March 2024. “The idea of putting everything in modules — reactor and all other components that comprise the broader plant — is to create one efficient assembly process,” says Fossen, director of public relations for Last Energy. Photo credit: Cat Clifford, Cipher News.

In addition to “modular,” another nuclear innovation term frequently applied to newer reactors is “advanced,” although what’s included in that umbrella term varies. To Crozat of NEI, the term applies whenever a reactor is “changing out something” from the reactors prevalent today to “pick up some capabilities.”

Those capabilities could include modular construction, passive safety systems (which use natural forces like gravity to prevent meltdowns) or “more exotic fuels and coolants,” said Katy Huff, a nuclear engineering professor at the University of Illinois Urbana-Champaign. Huff just completed a stint in the U.S. Energy Department’s Office of Nuclear Energy.

Faster reactions, new fuels, new coolants

Many of the advanced reactors being developed now are what are known as “fast reactors.”

In the most common type of nuclear reactor today, the fission reaction, or the splitting of an atom to create energy, takes place in water. The water acts as a moderator, slowing down the reaction, and as a coolant, preventing the system from overheating.

Fast reactors, in contrast, do not slow down the fission reaction. Faster reactions mean more reactions, squeezing more energy out of the same volume of fuel.

Fast reactors can even get energy out of fuel already spent by conventional reactors. To wit: the nation’s existing nuclear waste contains enough energy to power the entire country for 100 years with fast reactors.

Because of their efficiency, fast reactors can operate for longer periods before needing to be refueled.

Fast reactor designs also tend to use coolants other than water, influencing reactor construction.

TerraPower’s Natrium reactor uses sodium as a coolant. “Sodium is very heavy,” TerraPower’s Levesque said. “When the neutron hits the sodium atom, it’s like hitting a wall — it bounces off and doesn’t slow down.”

Conventional reactors have thick, expensive walls to boost the pressure inside and prevent the water from boiling off. Sodium, on the other hand, has a boiling point eight times higher than that of water. A sodium-cooled reactor doesn’t need to be pressurized in the same way, increasing safety and bringing construction costs down, Levesque told Cipher.

Even liquid metals are being tried as coolants. Westinghouse is developing a lead-cooled reactor because lead has such a high boiling point: 3,100 degrees Fahrenheit.

Editor’s note: TerraPower was founded by Bill Gates, who is also founder of Breakthrough Energy, which supports Cipher.