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Are nuclear power plants too expensive to build?

In the U.S., new nuclear electricity is pricier than most other energy sources, but arguably cheaper than other ways to get clean energy around the clock. In other countries, nuclear is much more able to compete with coal and gas.

March 25, 2026

The United States has the largest fleet of nuclear power plants in the world, providing around 17% of the country’s electricity.¹ But that wealth of nuclear energy is a legacy of a past era. Nearly all of these plants were built before 1990; since 2000, over 30 plans for new U.S. nuclear reactors have been canceled, while only three reactors have been built.²

There are several reasons construction slowed to a crawl, says Jacopo Buongiorno, professor of nuclear science and engineering and Director of the MIT Center for Advanced Nuclear Energy Systems, including “the fact that the plants were being built with increasing cost overruns and construction delays.”

In fact, the American nuclear industry seems to defy a common rule of engineering: As more reactors were built throughout the 1980s, the cost rose instead of falling. An MIT study, which Buongiorno co-authored, found that more stringent safety standards explain part of the rise, but safety is not the full story.³ The industry has also fallen victim to a larger trend.

“The productivity of the construction sector in the U.S. has been declining since the 1960s,” says Buongiorno. That impacts the cost of everything from housing to highways,⁴ and nuclear plants, which are very complex construction projects, have been especially affected.

Recent experience shows these problems are far from solved. The two newest reactors in the U.S. were finished in 2023 and 2024, both at the Vogtle Electric Generating Plant in Georgia. Their construction took 7 years longer than scheduled⁵ and cost around $15,000 for every kilowatt of generating capacity. That’s vastly higher than nuclear plants built in the 1970s, most of which cost less than $2,000 per kilowatt, adjusted for inflation.⁶

Is that too expensive? It depends what you’re trying to solve for. If you only want to deliver the cheapest electricity possible, these building costs are prohibitive. “At the moment, the cost per megawatt-hour of new nuclear is higher than almost anything else out there,” says Buongiorno. “Higher than solar and wind, higher than natural gas.”

If you’re also concerned about climate change and the reliability of the electric grid, the question gets more complicated. Like wind and solar—but unlike coal or gas—a working nuclear plant creates no climate-warming pollutants. And as part of an overall clean energy system, Buongiorno says, a mix with nuclear is cheaper than wind and solar alone. “Keeping a little bit of nuclear in the mix—it depends on the location, on the market, but roughly between 20 and 30% of your generation—actually reduces the overall cost,” he says.

That’s because, while wind and solar farms make impressively cheap electricity, they also lose output or shut down when weather conditions change. To supply round-the-clock electricity with wind and solar alone, we would need to “overbuild,” creating solar panels and wind turbines well in excess of our usual needs, plus batteries or other energy storage to tide us over when the weather doesn’t cooperate. As a recent MIT study argues, even at the eye-popping costs of the Vogtle project, nuclear energy may be no pricier in the long run than “firming” solar and wind with batteries, at least in some regions.⁷

“It sounds like a little bit of a paradox, right?” says Buongiorno. “Per megawatt-hour, nuclear is more expensive, but when you bring it into a balanced mix, it reduces the cost.”

Still, even the biggest supporters of nuclear power would admit that its hefty price tag is not helping the quest for 100% clean energy. And other countries’ nuclear programs don’t suffer from the same high costs we’ve seen in the United States. China, South Korea, India, and Russia all have active nuclear power industries that consistently build plants for comfortably under $3,000 per kilowatt.⁸

That price makes nuclear a much more attractive investment. “The cost of nuclear electricity,” says Buongiorno, “is primarily the cost of the plant.” Since nuclear energy’s operating costs—for uranium fuel, staff, and all the day-to-day expenses of running a power plant—are relatively low and stable, a plant that’s cheap to build is not only a useful complement to wind and solar, but possibly also competitive with coal and gas.

Could we get the same results here? Construction is likely to stay costly in the U.S. for the foreseeable future. But engineers could work on automating some construction processes and designing materials to be deployed faster on-site. Plus, the United States does not need to achieve South Korean levels of efficiency to make nuclear energy much cheaper and more broadly useful here. And Buongiorno argues that we can certainly improve on the Vogtle project.

Some of the costs at Vogtle, he says, were inevitable results of using a new reactor design, the AP1000, which had never been deployed in the U.S.. “First-of-a-kind projects are always problematic,” he says, “because there is a learning curve” as construction workers, managers, and suppliers learn how to work with a new design.

He also faults “a very unwise rush to build a plant before completing the detailed design, due to commercial pressure and some government incentives which had an expiration date.” Nuclear power is, for good reason, heavily regulated, so ongoing changes to the design required expensive work stoppages as regulators reviewed each change and suppliers adjusted to new orders for parts.

We can also put ourselves in a better position to learn by doing. In China, reactor designs and construction projects are standardized, low-interest state loans get projects off the ground, and a steady stream of construction lets the nuclear workforce go from site to site. This strategy has helped the country build over 50 reactors in the last 25 years, with dozens more on the way.⁶

“They're making the same thing over and over again,” says Buongiorno. “And every time they do it, they get better, and the cost goes down.”

The U.S. government is pursuing some of these steps now, brokering deals to build a larger fleet of AP1000 reactors and promising loans to help build them.⁹ Buongiorno is optimistic that costs will fall. “The policies are there, the support is there,” he says. “The real issues are financing, supply chain, and the ability of these companies to execute projects. You solve those three, then the floodgates may open.”

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