Nuclear Power Production in the US

Short answer

• Nuclear power is a major source of electricity in the United States. In 2024, nuclear power supplied 18 percent of US electricity generation, according to the US Energy Information Administration (EIA).
• As of March 2026, the EIA reported 94 operating commercial reactors at 54 nuclear power plants in 28 states, with combined net summer electricity generation capacity of 98,441 megawatts.
• A nuclear plant makes electricity by using heat from nuclear fission to make steam. The steam spins a turbine, and the turbine drives a generator.
• US nuclear plants run at high utilization. The EIA reported an average annual capacity factor of 91 percent for nuclear power plants in 2025, higher than the capacity factors for other types of power plants.
• Illinois has more reactors than any other state, with 11 reactors at 6 plants as of March 2026, according to the EIA. The largest nuclear power plant in the United States is Vogtle in Georgia, with four reactors and 4,530 megawatts of net summer capacity.
• The main challenges are not short term fuel supply alone. They are plant age, retirements, construction cost and time, waste storage, and competition from natural gas and renewables.

How Much Nuclear Power Does the US Produce?

Nuclear power production in the US is best understood in three different measures, and mixing them up causes most confusion. Capacity is how much electricity plants could produce at full output. Generation is how much electricity they actually produced over a period. Share is generation expressed as a percentage of total electricity generation.

On capacity, the picture as of March 2026 is clear in EIA data. The United States had 94 operating commercial reactors at 54 nuclear power plants in 28 states. Their combined net summer electricity generation capacity was 98,441 megawatts. Net summer capacity is a seasonal measure of what a plant can reliably deliver in summer conditions, so it is not the same as a nameplate rating stamped on equipment. It is still the standard comparison used by the EIA for the fleet as a whole.

On generation share, nuclear power remains one of the largest sources of US electricity, and the largest single fuel source of electricity that does not directly burn fossil fuel. The EIA reported nuclear power at 18 percent of US electricity generation in 2024, when total electricity generation was 4.30 trillion kilowatthours. Natural gas supplied 43 percent, renewables supplied 23 percent, coal supplied 15 percent, and petroleum supplied 0.4 percent in that same EIA summary for 2024. Those shares are rounded, so they do not add to exactly 100 percent.

That 18 percent share matters because it comes from a relatively small number of large plants. A plant with two or more reactors can supply a large region, so nuclear power supplies close to one fifth of US electricity from 54 plant sites. The share varies by year with demand, outages, retirements, new reactors, and growth in other sources, so a 2024 share should not be quoted as if it applied in every year.

How a Nuclear Power Plant Makes Electricity

At its core, a nuclear power plant is a heat engine. The heat source is different from a coal or natural gas plant, but the last steps are familiar: heat makes steam, steam spins a turbine, and the turbine drives a generator that produces electricity.

The heat comes from nuclear fission. In fission, the nucleus of an atom is split into smaller parts, releasing energy as heat. US commercial reactors use uranium fuel, and in particular the isotope uranium-235, whose atoms are easily split. The EIA explains that uranium fuel is formed into ceramic pellets, which are stacked in metal fuel rods, and bundles of fuel rods form fuel assemblies. A reactor core contains many fuel assemblies.

A controlled chain reaction is the key idea. When a uranium-235 nucleus splits, it releases neutrons as well as heat. Some of those neutrons go on to split other uranium nuclei, keeping the reaction going at a controlled rate. Control rods absorb neutrons and allow operators to raise or lower power, or to shut the reactor down. Water in most US reactors both carries heat away from the core and slows neutrons so that fission is more likely, a role known as moderation.

There are two main commercial reactor designs in the United States. In a pressurized water reactor, water passes through the core under very high pressure, so it stays liquid even though it is very hot. It then transfers heat through a steam generator to a separate, lower pressure water loop, which boils and drives the turbine. In a boiling water reactor, water boils directly in the core, and that steam drives the turbine. In both designs, steam is cooled back into water after the turbine and reused. Cooling may use a cooling tower or water from a lake, river, or ocean. Not every plant has tall cooling towers.

Capacity factor helps explain output. It compares actual generation over a year with the maximum if a plant had run at full capacity all year. The EIA reported an average annual capacity factor of 91 percent for US nuclear plants in 2025. That high figure is one reason a fleet with fewer reactors than in 2012 can still produce a large amount of electricity.

Where US Nuclear Power Is Produced

Most US commercial nuclear reactors are located east of the Mississippi River, according to the EIA. That geography reflects where the fleet was built, where population and electricity demand are concentrated, and where cooling water and transmission connections were available. Twenty-eight states had at least one commercial nuclear reactor as of March 2026.

Illinois leads the country on reactor count. As of March 2026, Illinois had 11 reactors at 6 plants, more than any other state. At the end of 2025, Illinois also had the largest total nuclear net summer electricity generation capacity of any state, at about 11,592 megawatts, according to the EIA. That combination of many reactors and large capacity makes Illinois the leading nuclear producing state in the fleet as it stands.

Other states with large nuclear fleets include Pennsylvania, South Carolina, Georgia, Alabama, North Carolina, Texas, Tennessee, Arizona, and Florida. Monthly generation rankings move with refueling schedules, so capacity and reactor count give a steadier picture than a single month.

The largest single plant is Vogtle in Georgia, with four reactors and 4,530 megawatts of net summer capacity, according to the EIA. Its newest reactor, Unit 4, began commercial operation in April 2024. As of March 2026, the EIA reported that 19 US plants had one reactor, 31 had two, 3 had three, and 1 had four. The largest single reactor is Grand Gulf in Mississippi, at about 1,400 megawatts, and the two smallest, each about 520 megawatts, are at Prairie Island in Minnesota. Compare both reactor count and capacity, not count alone.

Age is also important. The average age of US operating reactors was about 44 years as of March 2026, according to the EIA. The oldest, Nine Mile Point Unit 1 in New York, began commercial operation in December 1969. Most of the fleet was built in the 1970s and 1980s, which is why license renewal, uprates, and retirement decisions dominate current discussion.

A Brief History of US Nuclear Power Production

Commercial nuclear electricity generation in the United States began in 1958, with the first commercial plant at Shippingport, Pennsylvania, following the first controlled nuclear chain reaction demonstrated by Enrico Fermi and colleagues at the University of Chicago on December 2, 1942. The fleet grew rapidly in the 1970s and 1980s, and by the early 1990s nuclear power was supplying about one fifth of US electricity, a level it has broadly held since.

The accident at Three Mile Island Unit 2 in Pennsylvania in 1979 is part of that history, but it is not the subject of this article. For the production story, the relevant point is narrower: after 1979, new reactor orders effectively stopped for decades, safety regulation tightened, and construction of plants already underway continued into the late 1980s. Until 2013 there had been no new construction starts since 1977, according to World Nuclear Association summaries; construction of Vogtle Unit 3 started in March 2013 and of Unit 4 in November 2013. That long pause is why the fleet is old.

Since 2012, reactor numbers have declined as some older plants retired, yet generation has not fallen in proportion. The EIA points to uprates as a key reason. An uprate increases the capacity of an existing reactor, for example by improving turbines or pumps within safety limits. License renewals have had a similar effect, allowing plants first licensed for 40 years to operate for 60 years, with renewals to 80 years under consideration for some reactors by the US Nuclear Regulatory Commission (NRC). Restart plans for retired plants are targets, not completed facts, until a reactor returns to commercial service.

The Nuclear Fuel Cycle: From Mine to Storage

Nuclear power production does not begin at the power plant gate. It begins with uranium, and it ends with used fuel that must be stored safely for a long time. The US Nuclear Regulatory Commission describes the fuel cycle in stages, and the EIA describes the same cycle in front end and back end phases.

The front end prepares uranium for use. Uranium ore is recovered by mining or in situ leaching, then milled to produce uranium concentrate, sometimes called yellowcake. The concentrate is converted into uranium hexafluoride, then enriched to increase the concentration of uranium-235. Natural uranium contains just over 0.7 percent uranium-235. US commercial reactor fuel is typically enriched to between 3 percent and 5 percent uranium-235, according to the EIA. Enriched material is then fabricated into fuel pellets and fuel rods at fuel fabrication plants.

The fuel is loaded into a reactor and used until the assemblies must be removed. The length of a fuel cycle varies by plant design and operating plan, but fuel typically stays in a reactor for several years, with a portion replaced during each refueling outage. After removal, used fuel is highly radioactive and thermally hot. It is first stored in pools of water at the reactor site, where water cools it and provides shielding. After several years, it can be transferred to dry storage casks, which are robust steel and concrete containers designed for storage at the plant site.

The back end is where the United States differs from some other countries. Commercial reprocessing, which chemically separates usable uranium and plutonium from used fuel for reuse, is not currently done commercially in the United States, according to the NRC. The NRC also notes that no federal waste repository is currently licensed in the United States, and spent fuel remains in interim storage. That means, in practice, nearly all US commercial used fuel is stored at the reactor sites where it was produced, first in pools and then in dry casks, pending a future permanent disposition decision.

This is often described as an open or once through fuel cycle, in contrast to a closed cycle in which used fuel is reprocessed and recycled. It does not change how electricity is generated, but it means waste policy, rather than reactor physics, is the long term constraint on the back end. Uranium supply is a separate question: turning uranium into reactor fuel requires enrichment, conversion, and fabrication capacity that cannot be built overnight, and recent federal attention to domestic fuel production reflects supply chain concern rather than a shortage of uranium in the ground.

Why Nuclear Power Still Matters to the Grid

Nuclear plants provide steady output, running at high output for months between refueling outages, which helps meet demand at night, in winter, and when wind and solar output is low. Their large spinning turbines also help keep grid frequency stable when demand or supply changes suddenly, a service inverter connected renewables do not provide in the same way, although batteries can help.

Nuclear generation produces no carbon dioxide at the point of generation, because fission does not burn fuel. Mining, milling, enrichment, construction, and transport do use energy and produce emissions, so a full lifecycle figure is low but nonzero. The grid point is narrower: replacing a kilowatt hour from a coal or natural gas plant with one from an operating nuclear plant avoids the carbon dioxide that fossil plant would have emitted for that electricity.

The EIA counts nuclear separately from renewables. In 2024, nuclear was 8 percent of total primary energy production and 9 percent of consumption, while renewables were 9 percent in both measures. Do not confuse those primary energy figures, which include transport, industry, and heating, with the 18 percent electricity figure.

Cost is the counterweight. Nuclear plants are expensive and slow to build, but relatively inexpensive to operate once built, because fuel is a small share of total cost. That favors keeping existing plants running over building new large plants, and it explains interest in small modular reactors, which promise factory fabrication and smaller upfront investment, promises not yet proven at commercial scale in the United States.

Safety, Regulation, and Decommissioning

US commercial plants are licensed and inspected by the NRC, which reviews designs, issues construction and operating licenses, inspects plants, and enforces safety requirements. The EIA notes that NRC application review can take up to five years, and construction may take five years or more, which is part of the cost challenge.

Day to day safety rests on multiple barriers: ceramic fuel pellets, sealed metal fuel rods, a pressure vessel, and a containment structure designed to contain releases in an accident. Operators are licensed, and plants must be able to shut down safely and remove heat from the core even if normal power is lost. This principle of defense in depth, meaning several independent layers of protection, applies across the fleet.

When a reactor retires, decommissioning safely removes the facility from service and reduces residual radioactivity to a level that permits release of the site. According to the EIA, citing the NRC, 19 commercial reactors at 15 sites were in various stages of decommissioning as of March 2026. That is normal fleet turnover, not evidence of a safety failure at those sites. Safety regulation, public acceptance, and liability rules all affect whether plants keep operating and whether new plants are built.

Costs, Retirements, and Competition

US nuclear plants compete where natural gas often sets wholesale prices and where wind and solar have low operating costs once built. In some markets, prices have at times been too low for older, smaller nuclear plants to cover operating and maintenance costs, even though fuel is cheap. Several plants retired in the 2010s and early 2020s for economic reasons, or announced retirement before receiving support to stay open. State and federal programs that value carbon free electricity have changed that calculus for some plants, but program details change with legislation, so this article lists no payment rates or deadlines. Without a value on steady, carbon free output, a market paying only for energy each hour can undervalue a nuclear plant.

New large construction faces a different problem. Vogtle Units 3 and 4 took more than a decade from construction start to commercial operation and cost far more than first estimated, making utilities cautious about another large plant on the same model and strengthening interest in smaller, factory built reactors. Whether that approach delivers lower cost remains to be demonstrated by completed projects.

Demand growth cuts both ways. Data centers and electrification are raising demand in some regions, increasing the value of steady generation, but also the value of generation that can be built quickly. Nuclear power, with long lead times, suits long term supply planning better than rapid response to a sudden surge.

What Comes Next: Small Reactors, Restarts, and Projections

The most discussed future for US nuclear production has three parts: keeping the existing fleet running, restarting suitable retired plants, and building advanced reactors, including small modular reactors.

Keeping the existing fleet running means license renewals, uprates, and maintenance. As of October 2026, World Nuclear Association reporting noted subsequent renewals to 80 years approved for 25 reactors, with more under consideration by the NRC. That snapshot will change, but 60 year, and in some cases 80 year, operation is now a serious option, subject to safety review.

Restarts require careful wording. Palisades in Michigan, shut down in 2022, was reported in October 2026 as expected to restart in 2027. Crane Clean Energy Center, formerly Three Mile Island Unit 1, was reported as targeted for 2027 to 2028, and Duane Arnold in Iowa as targeted for early 2029. These are plans reported in 2025 and 2026, not operating reactors in the EIA March 2026 count, except for the EIA data note that operators of Palisades and Crane report those reactors as operating but out of service in its survey. Check current status before describing any restarted plant as operating.

Advanced reactors are the third part. Small modular reactors are designed for factory fabrication and modular assembly, and some designs use different coolants or fuels. Companies including TerraPower, X-energy, and Kairos Power have projects in development with federal support, according to recent reporting, but none had entered commercial electricity service at scale in the United States as of the period covered here.

The EIA Annual Energy Outlook 2026 Counterfactual Baseline case illustrates one modeled future: capacity remains relatively stable, rising to 99,000 megawatts in 2050, while the generation share falls from 17 percent in 2025 to between 12 percent and 15 percent by 2050, because total generation grows faster than nuclear generation in that case. A different policy or cost case would give a different result.

How to Read Nuclear Production Numbers Without Being Misled

Check the date first. Reactor counts, capacity, and shares change when plants retire, restart, or enter service, so a 2021 figure is not interchangeable with a March 2026 figure. Next, check whether a figure is capacity or generation: high US capacity factors lift generation above what capacity alone would suggest. Then check whether a share is of electricity or of all energy: nuclear is about one fifth of US electricity but under one tenth of total primary energy, because most energy use is not electricity. Also check project status: a design certification is not permission to construct a specific plant, and neither is an operating license. Finally, check whether a cost claim includes construction, operation, waste, and decommissioning, or only one part. A full comparison needs all parts, on the same basis.

Frequently Asked Questions

How much electricity does nuclear power produce in the US?

In 2024, nuclear power supplied 18 percent of US electricity generation, according to the EIA. As of March 2026, the EIA reported 94 operating commercial reactors at 54 plants in 28 states, with 98,441 megawatts of combined net summer capacity. Generation in any given year varies with outages, retirements, and new reactors entering service.

Which state produces the most nuclear power in the US?

Illinois has more reactors than any other state, with 11 reactors at 6 plants as of March 2026, and the largest total nuclear net summer capacity at the end of 2025, at about 11,592 megawatts, according to the EIA. Monthly generation rankings can shift with refueling schedules, so capacity and reactor count give a steadier comparison than a single month.

What is the largest nuclear power plant in the US?

Vogtle in Georgia is the largest nuclear power plant in the United States, with four reactors and 4,530 megawatts of net summer capacity, according to the EIA. Its Unit 4 began commercial operation in April 2024. The largest single reactor is Grand Gulf in Mississippi, at about 1,400 megawatts of net summer capacity.

How does a nuclear power plant generate electricity?

Fission in the reactor core produces heat. The heat makes steam, either directly or through a heat exchanger, depending on reactor design. Steam spins a turbine, and the turbine drives a generator that produces electricity. After passing through the turbine, steam is cooled back into water and reused.

Is nuclear power renewable?

No. Nuclear power is generally described as carbon free at the point of generation, but uranium is a mined, finite resource, so nuclear power is not renewable in the same sense as wind, solar, or hydropower. The EIA counts nuclear electric power separately from renewable energy in its statistics.

What happens to used nuclear fuel in the US?

Used fuel is first stored in water pools at the reactor site, then typically transferred to dry storage casks at the same site. Commercial reprocessing is not currently done in the United States, according to the NRC, and no federal waste repository is currently licensed, so interim storage at plant sites remains the practical arrangement pending a permanent disposition decision.

Are new nuclear power plants being built in the US?

No Vogtle-scale large commercial reactor was under construction in the United States at the time of the EIA March 2026 fleet count, following the completion of Vogtle Unit 4 in April 2024; the World Nuclear Association country profile likewise lists zero reactors under construction in that large-commercial count. That distinction matters: demonstration and small advanced-reactor projects, including Kairos Power’s Hermes reactors and TerraPower’s Natrium project, are in development, licensing, or early construction, but none had entered commercial electricity service at scale in the United States as of the period covered by this article. Restart plans for Palisades, Crane, and Duane Arnold are targets reported in 2025 and 2026, not completed operating facts.

Is nuclear power safe?

US commercial reactors are licensed and inspected by the NRC, and plants use multiple barriers, control systems, and containment structures. Safety is regulated on a plant by plant basis, and past accidents, including Three Mile Island Unit 2 in 1979, are part of the regulatory history. This article does not assess the safety of any individual plant, and readers with concerns about a specific plant should consult NRC inspection and licensing records for that plant.

Sources & references

• US Energy Information Administration, U.S. nuclear industry. Figures cited include the March 2026 reactor and plant count, capacity, state data, Vogtle data, capacity factor for 2025, and Annual Energy Outlook 2026 projection case. https://www.eia.gov/energyexplained/nuclear/us-nuclear-industry.php
• US Energy Information Administration, U.S. energy facts: data and statistics. Figures cited include 2024 total electricity generation and generation shares by source, and primary energy shares. https://www.eia.gov/energyexplained/us-energy-facts/data-and-statistics.php
• US Energy Information Administration, The nuclear fuel cycle. Front end and back end stages, uranium-235 share in natural uranium, and enrichment to 3 percent to 5 percent. https://www.eia.gov/energyexplained/nuclear/the-nuclear-fuel-cycle.php
• US Nuclear Regulatory Commission, Stages of the Nuclear Fuel Cycle. Fuel cycle stages, interim storage, and the note that no recycling or reprocessing facility or federal waste repository is currently licensed in the United States. https://www.nrc.gov/materials/fuel-cycle-fac/stages-fuel-cycle.html
• US Nuclear Regulatory Commission, Fuel cycle glossary entry. Definitions of fuel cycle stages and the note that commercial reprocessing is not practiced in the United States. https://www.nrc.gov/reading-rm/basic-ref/glossary/fuel-cycle.html
• International Atomic Energy Agency, What is Nuclear Energy? The Science of Nuclear Power. Explanation of fission, heat, steam, turbines, and generators. https://www.iaea.org/newscenter/news/what-is-nuclear-energy-the-science-of-nuclear-power
• Argonne National Laboratory, Science 101: Nuclear Energy. Explanation of fission, fuel rods and assemblies, water cooling, steam, turbines, and generators. https://www.anl.gov/science-101/nuclear-energy