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Here’s what you need to know about the nuclear power comeback — including what’s going on, what’s new this time, and is it safe?
For a while there, nuclear energy looked like it was on its way out. After taking off post-World War II, it lost momentum toward the dawn of the 21st century, when sagging public support and mounting costs led to dozens of cancellations in the U.S. and drove the rate of new proposals off a cliff. Only a few reactors have been built in the U.S. this century; the most recent, Georgia Power’s Plant Vogtle units 3 and 4, were years behind schedule and billions of dollars over budget. Vogtle-3 came online last summer, with Vogtle-4 — which was delayed even further by an equipment malfunction — expected to follow early this year.
It’s funny how time works, though. With demand for reliable zero-carbon energy rising, a new wave of nuclear developers is trying to recapture some of the industry’s long-lost momentum. They’re entering the race to net-zero with big ambitions — and much smaller reactor designs. Whether you’re wondering about the state of the U.S. nuclear power sector, what’s new about new nuclear, where the nuclear waste is going, and of course, whether it’s safe, read on.
Let’s start with the basics.
Nuclear reactors generate electricity using a process called fission. Inside the reactor’s core, a controlled chain reaction splits unstable uranium-235 into smaller elements; that process releases heat — a lot of heat.
The reactors in today’s U.S. nuclear fleet fall into two categories: boiling water reactors and pressurized water reactors. Each circulates water through the reactor core to manage the temperature and prevent meltdowns, and both use the heat produced by fission to create steam that powers turbines and thereby generates electricity. The main difference is in the details: Boiling water reactors use their coolant water to produce electricity directly, by capturing the steam, whereas pressurized water reactors keep their coolant water in a separate system that’s under enough pressure to prevent the water from turning to steam.
Some experimental reactors and newer commercial designs use different cooling systems, but we’ll get into those later. Lastly, while nuclear energy is not considered renewable, in the sense that it relies on a finite resource (enriched uranium) for fuel, it is a zero-emission energy source.
The sector emerged in the late 1950s and expanded rapidly over the next several decades. At its peak, the country’s nuclear fleet included 112 reactors — a number that has declined to about 90 today. Most of the surviving plants were built between 1970 and 1990.
The shrinkage has partly to do with the nuclear disarmament movement, which arose during the Cold War and grew to encompass nuclear power development, as well. (As it happens, much of the present day environmental movement has its roots in anti-nuclear activism.) Then there was the partial nuclear meltdown at Three Mile Island in 1979, which intensified existing public opposition to nuclear energy projects. That growing pushback, combined with reduced growth in electricity demand and the significant up-front investments nuclear plants required, caused some projects to be scrapped and fewer to be proposed. The Chernobyl nuclear disaster in 1986 seemed to confirm everyone’s worst fears.
Interest began to reemerge in the U.S. in the early 2000s as the budding public awareness of climate change cast doubt on the future viability of fossil fuels, but the 2011 Fukushima nuclear accident quashed many of those plans. The last U.S. nuclear plant to start up before Vogtle-3 entered construction in 1973 but was suspended for two decades before its completion in 2016.
As of 2022, 18.2% of U.S. electricity came from the country’s remaining nuclear reactors, according to federal data. That’s less than we’ve seen in decades.
The share of nuclear power on the grid has been slowly dwindling as aging reactors are shut down and other resources — mainly natural gas and renewables — have taken on a greater proportion of the country’s electricity-generating burden. The share of electricity from renewables surpassed energy from nuclear for the first time in 2021; in 2022, renewables contributed 21.3% of U.S. electricity.
Like coal and gas plants (and renewables when paired with sufficient storage), nuclear provides baseload power — meaning it sends electricity onto the grid at a consistent, predictable rate — as opposed to sources like wind and solar on their own, which provide intermittent supply. Electric utilities depend heavily on nuclear plants and other baseload resources to match supply with continuously fluctuating demand, accommodating the variability of wind and solar without sending too much or too little power onto the grid, which would cause power surges or blackouts.
Generating electricity using nuclear fission remains a divisive issue that cuts across partisan lines. In the inaugural Heatmap Climate Poll, nuclear came in a distant last among clean energy sources people feel comfortable having in their communities.
Some major environmental groups like the Sierra Club and Greenpeace maintain that the risk of serious disasters at nuclear power plants poses an unacceptable risk to communities and ecosystems. Others, including the Nature Conservancy, view it as a reliable low-carbon energy resource that’s — crucially — available to us today, while promising but immature options such as long-duration energy storage are still catching up.
Historically, nuclear has caused far fewer fatalities than fossil fuels, which generate all kinds of toxic, potentially deadly pollution — and that’s without factoring in their contribution to climate change and its associated disasters.
The companies now hoping to pioneer a new generation of nuclear reactors in the U.S. say their designs incorporate the lessons learned from the accidents in Chernobyl and Fukushima, putting even more safeguards in place than the fleet of reactors operating across the country today. (There’s still a debate over whether the proposed reactors will actually be safer, though.)
Spent uranium fuel is radioactive, and will remain radioactive for a very long time. As a result, there’s still a lot of disagreement about where that waste should go.
The federal government tried in the early 2000s to create a national repository in Nevada’s Yucca Mountain, but the project was stopped by intense local and regional opposition. The Western Shoshone, a tribe whose members have long faced exposure to radioactive fallout from nearby nuclear tests, sued the federal government in 2005. Harry Reid, a former U.S. Senator from Nevada who served as Majority Leader from 2007 to 2015, also fought against the repository.
In the absence of a central repository, the waste produced by nuclear plants is usually stored in deep water pools, which keep the spent fuel cool, or in steel casks onsite to keep the radiation from escaping into the surrounding environment.
If a repository eventually opens, some existing waste will likely be moved out of temporary storage and relocated there.
In short, the concrete behemoths that have long been the norm in the U.S. are really, really expensive to build. They also — like the two new Vogtle reactors — have a tendency to go way over their deadlines and budgets. That makes the electricity nuclear plants generate particularly expensive.
The vast majority of U.S. coal plants were built during the same few decades as most of the country’s nuclear reactors. But when utilities started to face more pressure to reduce their carbon emissions, toppling coal’s reign over the power sector, utilities wound up preferring to build cheaper — and, at least at the time, less controversial — natural gas power plants over nuclear power plants.
But public opinion is beginning to shift. About 57% of American adults favor building new nuclear power, a Pew Research Center survey found last year, compared with 43% in 2016. Though support is higher among Republicans than Democrats, it’s on the rise within both parties.
Today’s electric grid is a far cry from the 20th-century grid that traditional nuclear reactors were built for, and the new reactor models that are making the most headway reflect those changes. In general, these designs are smaller, cheaper (at least on paper), and more flexible than those already in operation.
Unlike traditional reactors, which generally require a lot of custom fabrication to be completed at the project site, small modular reactors — such as the ones being developed by NuScale Power — have components that are meant to be made in a factory, assembled quickly wherever they’ll operate, and combined with other modules as needed to increase power output. Fast reactors (so-named for their highly energized neutrons), like Bill-Gates-fronted TerraPower’s Natrium design, circulate coolants other than water through the core. (Natrium uses liquid sodium.)
Advocates of next-generation nuclear power are optimistic that the first such reactors will come online before the end of the decade. Several of the leading proposals have run into financial and logistical troubles over the last couple of years, however. In November, NuScale canceled its flagship project at the Idaho National Laboratory. It had been on track to be the first commercial small modular reactor built in the U.S. but was thwarted by rising costs, which caused too many expected buyers of its electricity to pull their support.
Nuclear’s image is recovering globally, too. Some of the companies working on demonstration reactors in the U.S. have been outspoken about wanting to see their designs supplant fossil fuels and provide abundant energy all over the world. Meanwhile, many countries are devoting plenty of their own resources to nuclear power.
Japan, which shuttered its sizable nuclear fleet in the aftermath of the Fukushima accident, is slowly bringing some of its nuclear capacity back online. In December, Japanese regulators lifted an operational ban on the Kashiwazaki-Kariwa Nuclear Power Plant, the largest nuclear plant in the world.
Nuclear power is also enjoying renewed popularity in parts of Europe, including France and the U.K. In France, where the long-dominant technology has faltered in recent years, a half-dozen new nuclear power plants are in the works, and even more small modular reactors could follow. The U.K. is also planning a new wave of nuclear development.
Elsewhere, including in Germany, nuclear hasn’t found the same traction. After delaying the closure of its last three nuclear reactors amid natural gas shortages caused by the war in Ukraine, Germany closed the reactors last spring, eliciting a mixed reaction from environmental groups.
Meanwhile, China has close to 23 gigawatts of nuclear capacity under construction — the “largest nuclear expansion in history,” Jacopo Buongiorno, a professor of nuclear science and engineering at MIT, told CNBC last year.
It’s still early days for most of the world’s next-generation nuclear reactors. With even the most promising designs largely unproven, there’s plenty of uncertainty about where today’s projects will ultimately lead. That makes it tricky to predict what role nuclear power will play in the energy transition over the coming decades.
There’s plenty of interest in building more capacity, however. In December, at COP28, the U.S. and 24 other countries — including Japan, Korea, France and the UK — signed on to a goal of tripling global nuclear energy capacity by 2050 in order to stay on track to reach net-zero emissions by then. Nuclear plants could also be an important source of carbon-free energy for producing green hydrogen, a nascent industry that got a major boost from tax credits under the Inflation Reduction Act.
But the U.S. Energy Information Administration’s most recent capacity forecast projects that the total amount of electricity from the country’s nuclear plants will decline in the coming decades — representing just 13% of net power generation by 2050.
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Investing in red states doesn’t make defying Trump any safer.
In the end, it was what the letters didn’t say.
For months — since well before the 2024 election — when asked about the future health and safety of the clean energy tax credits in the Inflation Reduction Act, advocates and industry folks would point to the 20 or so House Republicans (sometimes more, sometimes fewer) who would sign on to public statements urging their colleagues to preserve at least some of the law. Better not to pull out the rug from business investment, they argued. Especially not investment in their districts.
These letters were “reassuring to a lot of folks in clean energy and climate communities,” Chris Moyer, the founder of Echo Communications and a former staffer for longtime Senate Majority Leader Harry Reid, told me.
“I never felt reassured,” Moyer added.
Plenty of people did, though. The home solar company Sunrun, for instance, told investors in a presentation earlier this monththat a “growing number of Republicans in Congress — including 39 overall House members and four Senators — publicly support maintaining energy tax credits through various letters over the past few months.” The company added that “we expect a range of draft proposals to be issued, possibly including draconian scenarios, but we expect any extreme proposals will be moderated as they progress.”
Instead, the draft language got progressively worse for the residential solar industry, with the version that passed the House Thursday morning knocking billions of dollars off the sector, as tax credits were further squeezed to help make room for other priorities that truly posed an existential threat to the bill’s passage.
What Sunrun and others appear to have failed to notice — or at least publicly acknowledge — is that while these representatives wanted to see tax credits preserved, they never specified what they would do if their wishes were disregarded. Unlike the handful of Republicans who threatened to tank the bill over expanding the deduction for state and local taxes (each of whom signed one of the tax credit letters, at some point), or the Freedom Caucus, who tend to vote no on any major fiscal bill that doesn’t contain sizable spending cuts (so, until now, every budget bill), the tax credit Republicans never threatened to kill the bill entirely.
Ultimately, the only Republicans to outright oppose the bill did so because it didn’t cut the deficit enough. All of the House Republicans who signed letters or statements in support of clean energy tax credits voted yes on the legislation, with a single exception: New York’s Andrew Garbarino, who reportedly slept through the roll call. (He later said he would have voted for it had he been awake.)
“The coalition of interests effectively persuaded Republican members that tax credits were driving investment in their districts and states,” Pavan Venkatakrishnan, an infrastructure fellow at the Institute for Progress, told me in a text message. “Where advocates fell short was in convincing them that preserving energy tax credits — especially for mature technologies Republicans often view skeptically — should take precedence over preventing Medicaid cuts or addressing parochial concerns like SALT.”
The Inflation Reduction Act itself was, after all, advanced on a party-line basis, as was Biden’s 2021 American Rescue Plan. Combined, those two bills received a single Democratic no vote and no Republican yes votes.
In the end, Moyer said, Republican House members in the current Congress were under immense political pressure to support what is likely to be the sole major piece of legislation advanced this year by President Trump — one that contained a number of provisions, especially on SALT, that they agreed with.
“There are major consequences for individual house members who vote against the president’s agenda,” Moyer said. “They made a calculation. They knew they were going to take heat either way. They would rather take heat from clean energy folks and people affected by the projects.”
It wasn’t supposed to be this way.
White House officials and outside analysts frequently touted job creation linked to IRA investments in Republican House districts and states as a tangible benefit of the law that would make it politically impossible to overturn, even as Congress and the White House turned over.
“President’s Biden’s policies are leading to more than 330,000 new clean energy jobs already created, more than half of which are in Republican-held districts,” White House communications director Ben LaBolt told reporters last year, previewing a speech President Biden would give on climate change.
Even after Biden had been defeated, White House climate advisor Ali Zaidi told Bloomberg that “we have grown the political consensus around the Inflation Reduction Act through its execution,” citing one of the House Republican letters in support of the clean energy tax credits.
One former Biden White House climate official told me that having projects in Republican districts was thought by the IRA’s crafters to make the bill more politically sustainable — but only so much.
“A [freaking] battery factory is not going to save democracy,” the official told me, referencing more ambitious claims that the tax credits could lead to more Democratic electoral victories. (The official asked to remain anonymous in order not to jeopardize their current professional prospects.) Instead, “it was supposed to make it slightly harder for Republicans to overturn the subsidies.”
Congresspeople worried about jobs weren’t supposed to be the only things that would preserve the bill, either, the official added. Clean energy and energy-dependent sectors, they thought, should be able to effectively advocate for themselves.
To the extent that business interests were able to win a hearing with House Republicans, they were older, more traditionally conservative industries such as nuclear, manufacturing, agriculture, and oil and gas.The biofuels industry (i.e. liquid Big Agriculture) won an extension of its tax credit, 45Z. The oil and gas industry’s favored measure, the 45Q tax credit for carbon sequestration, was minimally fettered. Nuclear power was the one sector whose treatment notably improved between the initial draft from the House’s tax-writing committee and the version voted on Thursday. Advanced nuclear facilities can still claim tax credits if they start construction by 2029, while other clean energy projects have to start construction within 60 days of the bill’s passage and be in service by the end of 2028.
“I think these outcomes are unsurprising. In places where folks consistently engaged, things were protected,” a Republican lobbyist told me, referring to manufacturing, biofuels, and nuclear power, requesting anonymity because they weren’t authorized to speak publicly. “But assuming a project in a district would guarantee a no vote on a large package was always a mistake.”
“The relative success of nuclear is a testament to the importance of having strong champions — predictable but notable show of political might,” a second Republican lobbyist told me, who was also not allowed to speak publicly about the bill.
But all hope isn’t lost yet. The Senate still has to pass something that the House will agree with. Some senators had made noises about how nuclear, hydropower, and geothermal were treated in the initial language.
“Budget reconciliation is, first and foremost, a fiscal exercise,” Venkatakrishnan told me. “Energy tax credits offer a path of least resistance for hitting lawmakers’ fiscal targets. As the Senate takes up this bill, the case must be made that the marginal $100 billion to $200 billion in cuts seriously jeopardizes grid reliability and energy innovation.” Whether that will be enough to generate meaningful opposition in the Senate, however, is the $600 billion question.
A loophole created by the House Ways and Means text disappeared in the final bill.
Early this morning, the House of Representatives launched a full-frontal assault on the residential solar business model. The new language in the budget reconciliation bill to extend the Tax Cuts and Jobs Act passed Thursday included even tighter restrictions on the tech-neutral investment tax credits claimed by businesses like Sunrun when they lease solar systems to residential buyers.
While the earlier language from the Ways and Means committee eliminated the 25D tax credit for those who purchased home solar systems after the end of this year (it was originally supposed to run through 2034), the new language says that no credit “shall be allowed under this section for any investment during the taxable year” (emphasis mine) if the entity claiming the tax credit “rents or leases such property to a third party during such taxable year” and “the lessee would qualify for a credit under section 25D with respect to such property if the lessee owned such property.”
This is how you kill a business model in legislative text.
“Expect shares of solar companies to take a significant step back,” Jefferies analyst Julien Dumoulin-Smith wrote in a note to clients Thursday morning, calling the exclusion “scathing.” Investors are “losing the now false sense of security that we had 'seen the worst' of it with the initial House draft.”
Joseph Osha, an analyst for Guggenheim, agrees. “Considering the fact that ~70% of the residential solar industry is now supported by third-party (e.g. lease or PPA) financing arrangements, the new language is disastrous for the residential solar industry,” he wrote in a note to clients. “We believe the near-term implications are very negative for Sunrun, Enphase, and SolarEdge.”
Shares of Sunrun are down 37.5% in mid-day trading, wiping off almost $1 billion worth of value for its shareholders. The company did not respond to a request for comment. Shares of fellow residential solar inverter and systems Enphase are down 20%, while residential solar technology company SolarEdge’s shares are down 24.5%.
“Families will lose the freedom to control their energy costs,” Abigail Ross Hopper, chief executive of the Solar Energy Industries Association, said in a statement, in reference to the last-minute alteration to the investment tax credit.
When the House Ways and Means Committee released the initial language getting rid of 25D by the end of this year but keeping a limited version of the investment tax credit, analysts noted that Sunrun was an unexpected winner from the bill. It typically markets its solar products as leases or power purchase agreements, not outright sales of the system.
The reversal, Dumoulin-Smith wrote, “comes as a surprise especially considering how favorable the initial markup was” to the Sunrun business model.
“Our core solar service offerings are provided through our lease and power purchase agreements,” the company said in its 2024 annual report. “While customers have the option to purchase a solar energy system outright from us, most of our customers choose to buy solar as a service from us through our Customer Agreements without the significant upfront investment of purchasing a solar energy system.”
The new bill, Dumoulin-Smith writes is “‘leveling the playing field’ by targeting all future residential solar originations, whether leased or owned.” The bill is “negative to Sunrun with intentional targeting of the sector.
Last year, Sunrun generated over $700 million from transferring investment tax credits from its solar and storage projects. The company said that it had $117 million of “incentives revenue” in 2024, which includes the tax credits, out of around $1.4 billion in total revenue.
But the tax credits play a far larger role in the business than just how they’re recognized on the company’s earnings statements. The company raises investment funds to help finance the projects, where investors get payments from customers as well as monetized tax credits. Fund investors “can receive attractive after-tax returns from our investment funds due to their ability to utilize Commercial ITCs,” the company said in its report. Conversely, the financing “enables us to offer attractive pricing to our customers for the energy generated by the solar energy system on their homes.”
Morgan Stanley analyst Andrew Perocco wrote to clients that “this is a noteworthy change for the residential solar industry, and Sunrun in particular, which dominates the residential solar [third-party owned] market and has recognized ITC credits under 48E.”
Current conditions: A late-season nor’easter could bring minor flooding to the Boston area• It’s clear and sunny today in Erbil, Iraq, where the country’s first entirely off-grid, solar-powered village is now operating • Thursday will finally bring a break from severe storms in the U.S., which has seen 280 tornadoes more than the historical average this year.
1. House GOP passes reconciliation bill after late-night tweaks to clean energy tax credits
The House passed the sweeping “big, beautiful” tax bill early Thursday morning in a 215-214 vote, mostly along party lines. Republican Representatives Thomas Massie of Kentucky and Warren Davidson of Ohio voted no, while House Freedom Caucus Chair Andy Harris of Maryland voted “present;” two additional Republicans didn’t vote.
The bill will effectively kill the Inflation Reduction Act, as my colleague Emily Pontecorvo has written — although the Wednesday night manager’s amendment included some tweaks to how, exactly, as well as a few concessions to moderates. Updates include:
The bill now heads to the Senate — where more negotiations will almost certainly follow — with Republicans aiming to have it on President Trump’s desk by July 4.
2. FEMA cancels 4-year strategic plan, axing focus on ‘climate resilience’
The combative new acting administrator of the Federal Emergency Management Agency, David Richardson, rescinded the organization’s four-year strategic plan on Wednesday, per Wired. Though the document, which was set to expire at the end of 2026, does not address specific procedures for given disasters, it does lay out goals and objectives for the agency, including “lead whole of community in climate resilience” and “install equality as a foundation of emergency management.” In axing the strategic plan, Richardson told staff that the document “contains goals and objectives that bear no connection to FEMA accomplishing its mission.”
A FEMA employee who spoke with Wired stressed that while rescinding the plan does not have immediate operational impacts, it can still have “big downstream effects.” Another characterized the move by the administration as symbolic: “There are very real changes that have been made that touch on [equity and climate change] that are more important than the document itself.”
3. Energy Department redirects Puerto Rican rooftop solar investment to upkeep of fossil fuel plants
The U.S. federal government is redirecting a $365 million investment in rooftop solar power in Puerto Rico to instead maintain the island’s fossil fuel-powered grid, the Department of Energy announced Wednesday. The award, which dates to the Biden administration, was intended to provide stable power to Puerto Ricans, who have become accustomed to blackouts due to damaged and outdated infrastructure. The Puerto Rico Electric Power Authority declared bankruptcy in 2017, and a barrage of major hurricanes — most notably 2017’s Hurricane Maria — have destabilized the island’s grid, Reuters reports.
In Energy Secretary Chris Wright’s statement, he said the funds will go toward “dispatching baseload generation units, supporting vegetation control to protect transmission lines, and upgrading aging infrastructure.” But Javier Rúa Jovet, a public policy director for Puerto Rico’s Solar and Energy Storage Association, added to The Associated Press that “There is nothing faster and better than solar batteries.”
4. EDF, Shell, and others to collaborate on hydrogen emission tracker
The Environmental Defense Fund announced Wednesday that it is launching an international research initiative to track hydrogen emissions from North American and European facilities, in partnership with Shell, TotalEnergies, Air Products, and Air Liquide, as well as other academic and technology partners. Hydrogen is an indirect greenhouse gas that, through chemical reactions, can affect the lifetime and abundances of planet-warming gases like methane and ozone. Despite being a “leak-prone gas,” hydrogen emissions have been poorly studied.
“As hydrogen becomes an increasingly important part of the energy system, developing a robust, data-driven understanding of its emissions is essential to supporting informed decisions and guiding future investments in the sector,” Steven Hamburg, the chief scientist and senior vice president of EDF, said in a statement. Notably, EDF took a similar approach to tracking methane over a decade ago and ultimately exposed that emissions were “a far greater threat” than official government estimates suggested.
5. The best-selling SUV in America will now be available only as a hybrid
Toyota
The bestselling SUV in America, the Toyota RAV4, will be available only as a hybrid beginning with the 2026 model, Car and Driver reports. The car will be available both as a conventional hybrid and as a plug-in that works with CCS-compatible DC fast chargers, meaning “owners can quickly fill up its battery during long road trips” to minimize their fossil fuel mileage, The Verge adds. The RAV4 will also beat the Prius for electric range, hitting up to 50 miles before its gas engine kicks in.
Toyota’s move might not come as a complete surprise given that the automaker already introduced a hybrid-only lineup for its Camry. But given the popularity of the RAV4, Car and Driver notes that “if you ever wondered whether or not hybrids have entered the mainstream yet, perhaps this could be a tipping point.”
Nathan Hurner/USFWS
The Fish Lake Valley tui chub, a small minnow threatened by farming and mining activity, could become the first species to be listed as endangered under the second Trump administration.