What Is Nuclear Energy, and Why Is It Making a Comeback?

Energy security concerns augmented by recent years of war in Ukraine and the Middle East have fueled a global resurgence of nuclear energy. In Asia, Europe, and elsewhere, governments are looking to nuclear energy as a stable power source in the face of geopolitical uncertainty, increasing electricity demand, and accelerating climate change. This includes the United States, which recently signed a thirty-year civil nuclear cooperation agreement with Saudi Arabia, though it has yet to go into effect. This resurgence marks a stunning reversal. Nuclear power development stalled after high-profile accidents such as the 1979 Three Mile Island meltdown and the 1986 Chernobyl disaster fueled public fears of the technology.

“This is the brightest moment for nuclear power globally in a couple of decades,” Vijay Vaitheeswaran, senior fellow and director of CFR’s Energy and Climate Program, told CFR. “Energy for development and prosperity is extremely important… and we have a climate crisis as well as a challenge of local emissions. So nuclear, and more of it, would be a very good thing if the challenging economics of new plants can be overcome.”

As of 2024, there are 417 nuclear power reactors operating across 31 countries, with dozens more under construction, according to the International Atomic Energy Agency (IAEA) [PDF]. Together, they supply roughly 9 percent of the world’s electricity, a share that energy experts expect will grow in the coming decades as countries expand their nuclear commitments to meet booming demand.

CFR examines what’s driving renewed global interest in nuclear energy, which countries use it most, and the debate over its risk—including weapons proliferation. 

What is nuclear energy, and how does it work?

Nuclear energy is generated through nuclear fission, the process through which the nucleus of an atom splits into two or more nuclei, releasing large amounts of energy, mostly as heat and radiation. In a nuclear power plant, this heat is used to produce steam, which drives turbines connected to electric generators. 

Nuclear reactors are commonly fueled by uranium-235, a naturally occurring isotope of uranium. The result is low-carbon electricity. Nuclear-generated electricity prevents more than 470 metric tons of carbon dioxide emissions from entering the atmosphere that would otherwise come from fossil fuels, according to the Nuclear Energy Institute. However, the waste produced by nuclear power plants is radioactive and requires careful, long-term storage, fueling debate about nuclear energy as a clean climate solution. 

The development of civilian nuclear power became an international focus in the early 1950s, according to the IAEA [PDF]. In 1951, the Experimental Breeder Reactor-I in Idaho became the world’s first reactor to generate usable electricity from nuclear fission. However, nuclear power development slowed [PDF] in the United States in the 1970s and 1980s due to increased concern over reactor safety, waste disposal, and other environmental effects. 

Why is nuclear energy making a global comeback?

Experts say a combination of factors is driving nuclear energy’s comeback, which gained significant momentum in 2023, when more than twenty countries committed to tripling their global nuclear energy capacity by 2050. 

Energy diversification. Geopolitical instability has underscored countries’ need to diversify their energy sources. Russia’s 2022 invasion of Ukraine exposed Europe’s dependence on Russian natural gas imports, while the Iran war has significantly disrupted global oil and gas markets this year, highlighting the vulnerability of relying on fossil fuel supply chains to meet energy needs. Although the push for nuclear energy was already well underway before the Iran war began in February 2026, experts say these geopolitical conflicts have likely accelerated the process.  

Climate goals. This summer’s record-breaking heat and devastating wildfires have once again raised alarms about climate change. Faced with such mounting pressures, governments around the world are expanding their use of low-carbon electricity sources—such as nuclear, solar, and wind—to lower greenhouse-gas emissions and meet their climate goals. In a high-case scenario, the IAEA projects that global nuclear capacity will nearly triple by 2050, up from 377 gigawatts (GW) to 992 GW. In a low-case projection, capacity would increase by about 50 percent.

Advocates of nuclear power point out that it provides 24/7 power regardless of the weather, while low-carbon alternatives like wind and solar rely on energy-storage technologies like batteries to provide reliable power to the grid.

However, mining and refining uranium—the primary fuel source for nuclear energy—and building nuclear power plants requires large amounts of money and energy. Even so, the environmental gains outweigh the upfront costs required to build a nuclear energy plant, Vaitheeswaran told CFR. “Compared to something like coal, nuclear has very low climate or local emissions, and that’s very attractive in an age of great concern about climate change,” he said. 

AI demand. Nuclear energy presents a way to reduce the strain put on electrical grids by the rapidly expanding use of artificial intelligence (AI). Data centers accounted for roughly 50 percent of total electricity demand growth in the United States in 2025, according to the International Energy Agency. In the United States and globally, nuclear energy is seen as one way to meet this added demand. Major tech and AI infrastructure companies—including Amazon, Google, Meta, and Microsoft—have signed at least one nuclear deal in 2026. Before their recent interest in nuclear, these U.S. companies were the main force developing clean energy in the country with wind and solar power purchase agreements, he added. 

Which countries use the most nuclear energy?

Just five countries produce more than 70 percent of the world’s nuclear electricity generation capacity: the United States, China, France, Russia, and South Korea, according to the U.S. Energy Information Administration. 

The United States leads in nuclear energy production, accounting for about 30 percent of global electricity generation. The Trump administration aims to further increase production, with the goal of quadrupling U.S. nuclear capacity from 100 to 400 GW by 2050—close to the total amount of nuclear power currently generated worldwide. To achieve this, the administration plans to expedite the construction of ten large-scale commercial nuclear reactors by up to three years, with complete designs under construction by 2030. It also intends to encourage the building of more small modular reactors, compact nuclear fission plants that, in theory, require less time and money to set up compared to traditional large-scale plants. 

Some experts consider the administration’s plans to be overly ambitious. “The administration wants to do everything all at once,” CFR climate and energy expert David Hart said. “I don’t think they can. I think we really need to concentrate on a small number of designs and try to build a bunch of them, and I don’t quite see that happening in our current policy.”

Other countries are also ramping up their nuclear production. China is leading the world in building new units, with nearly forty currently under construction, and aims to surpass the United States as the world’s leader in nuclear capacity. Hart—who will direct a new CFR Task Force on Energy Security, Technological Innovation, and American Leadership—said nuclear power will be another pillar of China’s energy strategy, in addition to its edge in clean energy. However, the topic carries extra weight due to its connection to nuclear proliferation, he added. 

Elsewhere in Asia, the energy crisis caused by the U.S.-Iran war has left many countries looking to alternative power sources such as nuclear to reduce their reliance on imported crude oil and liquified natural gas. 

Europe is taking similar steps. The European Parliament passed a law in 2022 classifying certain natural gas and nuclear energy activities as climate-friendly investments to transition away from coal and achieve its climate goals. France, which generates roughly 70 percent of its electricity from nuclear power—the highest share in the world—is leading Europe’s revival of nuclear energy. Other European Union countries expanding domestic nuclear capacity include Hungary and Slovakia. 

Is nuclear energy clean and renewable?

Increased investment in nuclear energy is largely fueled by a desire for cleaner sources. Nuclear energy is not entirely renewable because it requires the mining of uranium. However, a major appeal of nuclear power is that it generates electricity without producing greenhouse gas emissions during operation. It is also seen as a more stable source of electricity than fossil fuels because nuclear reactors can operate continuously for long periods of time, providing reliable baseload power—the minimum amount of continuous electricity a power grid needs to supply 24/7. Hart said nuclear power’s biggest advantage is its ability to provide energy over the long term, with the operating lifespans of some nuclear reactors stretched to approximately eighty years.

Global public opinion over the last decade has grown increasingly supportive of nuclear energy, according to the World Nuclear Association. In the United States, more than 70 percent of respondents in a 2025 Bisconti Research survey said they favored using nuclear energy. A Gallup poll released earlier this year showed American support for nuclear energy had grown over the past decade.

This shift marks a reversal from the 1980s and 1990s, when nuclear development was largely stagnant. Experts say that slowdown, fueled in part by major nuclear disasters such as Chernobyl, cost the United States valuable production time. “We did slow our rate of build out for a time, and some would argue the bill is coming due,” CFR expert Erin Dumbacher said. “It’s now time to reinvest or come up with some alternative solution.” 

Is nuclear energy safe?

Opponents argue that expanding nuclear energy poses safety and security risks that need to be taken seriously. Disposal of nuclear waste remains a concern, Hart said, and there hasn’t been much progress made in finding a waste solution since he worked at a nuclear waste repository forty years ago. 

Experts also warn that increased investment in nuclear energy brings nuclear proliferation risks because of the dual-use nature of nuclear technology. Civilian nuclear programs can provide countries with access to the nuclear materials, facilities, and expertise needed to produce fissile material for nuclear weapons. However, the likelihood that risk becomes a reality depends on a country’s fuel sources, security measures, and governance models. Dumbacher said that building nuclear power plants in or near conflict zones carries additional risks, as demonstrated by the safety fears surrounding Ukraine’s Zaporizhzhia nuclear power plant, which has been heavily targeted by Russia during the war.

Concerns of weapon proliferation resurfaced most recently after the signing of a U.S.-Saudi nuclear deal in July 2026. The deal falls short of the standards for nonproliferation controls, inspections, and IAEA involvement established in previous U.S. nuclear agreements. Vaitheeswaran said the deal weakens the norms established under the 2009 U.S. civil nuclear deal with the United Arab Emirates, widely considered a “gold standard” for nonproliferation. “Certainly the [U.S.-Saudi] agreement, as declared, does represent a shift in policy for the United States—and from the point of proliferation, not necessarily a good one,” he added.

But perhaps the biggest obstacle to the nuclear resurgence is the economics of new plants, Vaitheeswaran told CFR. No new nuclear plant has been built on time and on budget outside of China, Russia, or South Korea in the last twenty years—and in the United States and Europe, development has been an utter disaster. 

“In the early days of the industry, boosters claimed that nuclear power would be ‘too cheap to meter,’” Vaitheeswaran said. “Today, unless innovative policies and technologies produce nuclear power faster and cheaper than in the recent past, nuclear will be remembered as too costly to matter.”