Which companies build nuclear reactors?

Many companies around the world design and build nuclear reactors for electricity generation. The industry includes established manufacturers of large power plants, state-owned nuclear companies, and newer firms developing small modular reactors (SMRs) and advanced reactor technologies.

Major nuclear reactor manufacturers

These are some of the most important companies, grouped by country and technology. Design Certification Applications for New ReactorsNuclear IndustryWho builds nuclear reactors

1. Westinghouse Electric Company

United States

One of the world's major reactor designers. Its AP1000 is a large pressurized-water reactor used in commercial nuclear power plants. It also provides reactor fuel, engineering and maintenance services.

Website: westinghousenuclear.com

2. GE Vernova Hitachi Nuclear Energy

United States / Japan

Builds boiling-water reactor technology, including the ABWR, and develops the BWRX-300 small modular reactor.

Website: gevernova.com/nuclear-power

3. Framatome

France

A major nuclear engineering and equipment company. It is associated with the EPR, a large-generation reactor design, and supplies nuclear fuel and services.

Website: framatome.com

4. Rosatom

Russia

State-owned nuclear conglomerate that designs, supplies and constructs reactors internationally, particularly VVER pressurized-water reactors.

Website: rosatom.ru

5. Korea Hydro & Nuclear Power (KHNP)

South Korea

Develops and delivers large reactors, including the APR1400. It is a major participant in international nuclear plant construction.

Website: khnp.co.kr

6. Mitsubishi Heavy Industries (MHI)

Japan

Designs pressurized-water reactors and manufactures major nuclear plant equipment.

Website: mhi.com

7. China National Nuclear Corporation (CNNC)

China

A major state-owned nuclear company responsible for reactor technology and construction, including the Hualong One design.

Website: cnnc.com.cn

Other significant players include China General Nuclear Power Group (CGN), AtkinsRéalis (Canada, associated with CANDU reactors), and Nuclear Power Corporation of India Limited (NPCIL). Nuclear IndustryWho builds nuclear reactors

Companies developing small modular and advanced reactors

These companies are particularly relevant if you're interested in newer reactor designs, factory-built units, or the future of nuclear power.

NuScale Power - United States

Develops small modular light-water reactors designed to supply electricity through modular nuclear power units.

nuscalepower.com

TerraPower - United States

Develops advanced nuclear reactors, including the Natrium sodium-cooled reactor concept, with integrated energy storage.

terrapower.com

X-energy - United States

Develops the Xe-100 high-temperature gas-cooled reactor, aimed at electricity generation and industrial heat.

x-energy.com

Kairos Power - United States

Developing fluoride-salt-cooled advanced reactors, with a focus on demonstrating its technology before commercial deployment.

kairospower.com

Oklo - United States

Developing compact advanced fission powerhouses intended to provide reliable power to industrial sites and other customers.

oklo.com

These five companies are reactor developers, but their designs are at different stages of licensing, demonstration and commercialization. They should not all be treated as established manufacturers of commercially operating reactors. Pre-Application Activities for Advanced ReactorsTable of Contents

Which companies should you look at?

One important distinction: a reactor designer, reactor manufacturer, and nuclear plant construction contractor are not necessarily the same company. For example, Bechtel is a major engineering and construction contractor, while Westinghouse supplies reactor technology. Nuclear PowerWho builds nuclear reactors

Are you looking at these companies as potential investments, suppliers for a nuclear power project, or companies leading the next generation of nuclear technology? The best shortlist changes quite a bit depending on your goal.

Nuclear reactor design, construction, and heavy component manufacturing are dominated by a mix of multinational corporations, state-owned enterprises, and specialized energy firms.

The primary companies that build nuclear reactors globally fall into a few major categories:

1. Major Global Reactor Vendors & Designers

• Westinghouse Electric Company (United States / Canada): A historical pioneer in nuclear energy, Westinghouse is famous for its AP1000 large pressurized water reactor (PWR) and its newer AP300 Small Modular Reactor (SMR), as well as the eVinci microreactor. North America Nuclear Reactor Construction Companies

• GE Vernova / GE-Hitachi Nuclear Energy (United States / Japan): A joint venture combining American and Japanese industrial powerhouses, GE-Hitachi is a leader in boiling water reactors (BWRs) and is currently advancing its BWRX-300 small modular reactor design. North America Nuclear Reactor Construction Companies

• Framatome / EDF (France): EDF is Europe's leading nuclear operator, while its subsidiary Framatome specializes in nuclear reactor design, engineering, and fuel manufacturing. They build large Evolutionary Power Reactors (EPRs).

• Rosatom (Russia): The Russian state-owned nuclear corporation is one of the most prolific builders of large-scale nuclear reactors globally, actively constructing VVER-design reactors both domestically and internationally (e.g., in Turkey, Egypt, Hungary, and India).

• China National Nuclear Corporation (CNNC) & China General Nuclear Power Group (CGN) (China): Backed by massive state support, these companies build the bulk of China's domestic nuclear fleet (such as the Hualong One reactor) and are increasingly exporting nuclear technology.

• Mitsubishi Heavy Industries (Japan): A major original equipment manufacturer (OEM) that builds critical heavy nuclear components (like steam generators and reactor pressure vessels) and partners heavily on international reactor projects. North America Nuclear Reactor Construction Companies

2. Specialized Components, Services, & Advanced SMR Developers

• BWX Technologies (BWXT) (United States): A key manufacturer of heavy nuclear components, reactor pressure vessels, and nuclear fuel. BWXT also builds naval nuclear reactors for the U.S. Navy's submarines and aircraft carriers. North America Nuclear Reactor Construction Companies

• NuScale Power (United States): A pioneer in Small Modular Reactors (SMRs), NuScale designs factory-built, smaller-scale nuclear power modules.

• NANO Nuclear Energy (United States): A newer player focusing on portable, advanced microreactors (like the KRONOS MMR) and nuclear fuel fabrication/transportation pipelines. NANO Nuclear Energy | SMALLER SIMPLER SAFER

• Holtec International (United States): Specializes in dry storage, decommissioning, and the development of its own SMR-300 reactor design.

Are you looking into reactor builders from an investment angle, or researching a specific technology like Small Modular Reactors (SMRs)?

The global nuclear energy landscape features a mix of traditional heavy industrials that build large-scale gigawatt reactors and next-generation innovators focused on Small Modular Reactors (SMRs) and microreactors. This momentum is heavily driven by tech giants partnering with reactor companies to secure 24/7 low-carbon power for AI data centers. NANO Nuclear Energy | SMALLER SIMPLER SAFERTop 10: Nuclear Energy Companies | Sustainability MagazineTop Companies Shaping the Future of Nuclear EnergyThe Best Nuclear Energy Stocks to Buy and Hold for DecadesKairos Power | Advanced Nuclear Reactor Technology4 U.S. Companies Defining the Future of Nuclear Energy

The industry's major players are organized below by their primary focus areas.

🏢 Next-Generation & Small Modular Reactor (SMR) Companies

These companies are reimagining the grid by building factory-assembled, smaller, and safer modular reactors. Five Startups Powering the Nuclear Energy Transition

• • NuScale Power : A prominent SMR developer and the creator of the NuScale Power Module (NPM). It remains a rare example of an SMR design achieving certification from the U.S. Nuclear Regulatory Commission (NRC). NuScale Power | Small Modular Reactor (SMR) Nuclear Technology

• Oklo Inc. : Backed by Sam Altman, Oklo is developing the Aurora small fast reactor. It utilizes liquid metal coolant and is capable of running on both fresh uranium and recycled nuclear waste. [Yahoo Finance]

• Kairos Power : Specializing in fluoride salt-cooled high-temperature reactors, Kairos Power has partnered with Google to deploy a commercial fleet of advanced reactors to supply clean energy. [Kairos Power]

• X-energy : Focuses on high-temperature gas-cooled reactors (like the Xe-100) and proprietary TRISO-X pebble fuel, working closely with international utilities like Centrica in the UK. X-energy

• NANO Nuclear Energy : A microreactor company developing highly portable systems like the KRONOS solid-core battery reactor and the LOKI portable, space-capable microreactor. [NANO Nuclear Energy]

🏗️ Traditional Large-Scale Reactor Manufacturers & Engineering

These established giants design and manufacture the massive traditional reactors that power the bulk of the global fleet. [Sustainability Magazine]

• • Westinghouse Electric Company : One of the oldest names in nuclear technology, famous for its flagship AP1000 pressurized water reactor, which is being deployed across the U.S., Europe, and China.

• GE Vernova : Formed via the General Electric spin-off, its nuclear division (GE Hitachi) is building both large-scale systems and the BWRX-300 small modular reactor.

• Framatome : A major French international manufacturer owned primarily by EDF, specializing in heavy components and reactor engineering services.

• China National Nuclear Corporation (CNNC) : A massive, state-owned enterprise that leads reactor design, construction, and operation throughout China, manufacturing indigenous designs like the Hualong One. List of companies in the nuclear sector - WikipediaWestinghouse | Nuclear's First. Nuclear's Next. | Westinghouse

⚡ Major Nuclear Utility Operators

These corporations do not typically design the reactors, but they own, manage, and operate the power plants that generate electricity. [YouTube·VanEck]

Are you exploring these companies from an investment angle , looking for career/engineering opportunities , or researching a specific reactor type (like SMRs or fusion)?

Major nuclear reactor builders include Rosatom, Westinghouse, Framatome, GE Vernova Hitachi, China National Nuclear Corporation, Mitsubishi Heavy Industries, EDF, and AtkinsRéalis (CANDU). In the U.S., TerraPower is also building its first advanced reactor.(mordorintelligence.com)(nuclearchain.net)(cnbc.com)

Major companies that build nuclear reactors include state-owned giants like Rosatom (Russia), CNNC/CGN (China), EDF/Framatome (France), and KHNP (South Korea), as well as private firms such as Westinghouse (USA), GE Hitachi (USA/Japan), Rolls-Royce SMR (UK), and newer players like NuScale, TerraPower, and Oklo (USA).Every Small Modular Reactor Company in 2026: The Complete List | smrintel.comTop Nuclear Power Companies 2026: Reactor OEMs, Fuel-Cycle Leaders, EPC Contractors - Industry News | SpecForgeNuclear reactor vendors · Reactor AtlasWho builds nuclear reactors | NuclearChain

🌍 Global Nuclear Reactor Builders

🔑 Key Insights

• State-owned enterprises dominate large-scale reactors: Rosatom, CNNC, CGN, EDF, and KHNP are responsible for most gigawatt-scale plants worldwide.

• Private innovators lead in small modular reactors (SMRs): NuScale, TerraPower, Oklo, Holtec, and X-energy are pioneering advanced designs with smaller footprints and flexible deployment.

• Technology diversity: While pressurized water reactors (PWRs) remain the global standard, advanced designs include fast reactors, molten salt reactors, and high-temperature gas reactors.

• Global expansion: Countries like Turkey, UAE, and Finland rely on foreign vendors (Rosatom, KHNP, EDF) for their nuclear buildouts.

⚠️ Risks & Challenges

• Cost overruns and delays: Projects like Flamanville (France) and Vogtle (USA) highlight the financial risks of large nuclear builds.

• Geopolitical dependence: Many nations rely on Russian or Chinese vendors, raising energy security concerns.

• Licensing hurdles: Advanced SMRs face lengthy regulatory approval processes, slowing commercialization.

Would you like me to focus on traditional large-scale reactor builders (like Rosatom, EDF, CNNC, KHNP, Westinghouse) or emerging SMR companies (NuScale, TerraPower, Oklo, Rolls-Royce SMR)? The answer depends on whether you’re interested in today’s dominant suppliers or the future of nuclear technology.