As of January 2025, there are 413 nuclear reactors in operation worldwide, generating approximately 9% of global electricity. The global nuclear power generating capacity has reached an all-time high, driven primarily by new reactors in China and Russia, but also supported by Japan and the United States as they restart and maintain existing facilities. In 2023, nuclear electricity generation rose to about 2,602 TWh, with projections for 2024 indicating an increase to around 2,650 TWh.
Nuclear reactors generate electricity by heating water to produce steam, which drives turbines connected to generators. This process relies on nuclear fission, in which heavy atomic nuclei split into smaller fragments, releasing a significant amount of energy. Unlike fossil fuel plants, which burn fuel to generate heat, nuclear reactors harness the heat generated from fission reactions to produce steam.
Nuclear fuel primarily consists of uranium or plutonium isotopes. These materials undergo fission reactions in the reactor core, releasing energy in the form of heat. The heat is used to produce steam, which drives turbines to generate electricity.
While nuclear energy is among the safest sources, incidents can occur. The most notable was the Fukushima Daiichi disaster in 2011. In 2023, several minor incidents and equipment breakdowns were reported at U.S. and European nuclear plants, but these were addressed quickly, with no significant radiological releases. The ongoing conflict in Ukraine has raised concerns about the Zaporizhzhia Nuclear Power Plant (ZNPP), with military activity increasing risks, including direct attacks on infrastructure. The International Atomic Energy Agency (IAEA) is closely monitoring the situation.
Nuclear waste is categorized into three types: low-level waste (LLW), intermediate-level waste (ILW), and high-level waste (HLW). LLW includes items like contaminated clothing and tools, which are stored in secure facilities for disposal or recycling. ILW, such as reactor components and resins, requires shielding during handling and is often solidified in concrete or bitumen for safe disposal. HLW, including spent nuclear fuel, is the most hazardous and requires long-term management. The preferred solution for HLW is geological disposal, where it is stored deep underground in stable geological formations. Treatment methods for these waste types include incineration for LLW, cementation for ILW, and vitrification for HLW to convert it into a stable, glass-like form for long-term storage.
Small Modular Reactors (SMRs) are gaining traction, with over 80 designs in development worldwide due to their enhanced safety and cost efficiency. The world's first floating nuclear power plant, the Akademik Lomonosov, has been operational in Russia since 2020.
In June 2024, TerraPower began construction on the Natrium reactor in Wyoming, marking the first advanced reactor project in the Western Hemisphere. Additionally, next-generation reactors like sodium-cooled fast reactors (SFR) and high-temperature gas reactors (HTGR) are being developed to improve efficiency and safety.
Existing reactors are also being upgraded with advanced materials and systems to extend their operational life and enhance performance, contributing to a broader commitment to expanding nuclear energy.
The U.S. remains the world’s largest producer of nuclear power, generating approximately 30% of global nuclear electricity. As of January 2025, 94 operational reactors across 28 states produced 775.4 terawatt-hours (TWh) of electricity in 2023, accounting for 18.6% of the nation’s total electricity generation.
There are ambitious goals to deploy 200 GW of net new nuclear capacity by 2050, aiming to triple current U.S. capacity. This initiative is supported by legislation providing incentives for nuclear development. Recent developments include the completion of Vogtle Units 3 and 4 in Georgia, with Unit 3 connected to the grid in 2023 and Unit 4 in 2024. Plans are also underway to restart reactors like Three Mile Island Unit 1 in Pennsylvania by 2028.
Additionally, there is growing interest in advanced technologies such as Small Modular Reactors (SMRs) and microreactors. In January 2025, Constellation Energy announced its acquisition of Calpine Corp for $16.4 billion, combining nuclear and renewable assets to create the largest independent power producer in the U.S.
Despite challenges, including high upfront costs and regulatory hurdles, increasing demand for low-emission energy sources from sectors like data centers and AI is expected to drive continued investment and innovation in nuclear energy.
Global nuclear power generation is set to reach an all-time high in 2025, with a projected 3.5% increase. The International Energy Agency (IEA) forecasts global nuclear generating capacity to rise from 416 GWe in 2023 to 647 GWe by 2050 under current policies, with more ambitious scenarios reaching up to 1017 GWe.
China and Russia lead the expansion, with China having 30 reactors under construction. Other regions are contributing, with Asia expected to account for 30% of global nuclear generation by 2026. Europe is renewing interest, and countries like Ghana, Poland, and the Philippines are developing their first nuclear plants. Over 30 countries are planning or considering nuclear power, with 20 more expressing interest.
Small Modular Reactors (SMRs) are gaining traction, with over 80 designs in development, and the first projects outside China and Russia expected to come online by 2030. Policy support is growing, with over 20 countries aiming to triple global nuclear capacity by 2050. Global investment in nuclear is projected to exceed $100 billion annually by 2030.
Technological advancements, including sodium-cooled fast reactors (SFR) and high-temperature gas reactors (HTGR), are expected to improve efficiency and sustainability, strengthening nuclear energy's role in future global energy mixes.