Nuclear energy remains one of the world’s largest sources of low-carbon electricity, with a fleet that runs at high capacity factors and a construction pipeline increasingly concentrated in a handful of countries.
Record global nuclear generation:2,667 TWh in 2024 (highest ever recorded).
Nuclear share of global electricity: about 9% (2024).
Installed nuclear capacity: about 420 GW worldwide (2024).
Global average capacity factor: about 83% (2024).
Reactors in operation:413 operating reactors totaling 377.1 GW(e) net capacity (PRIS last update: 2026-02-22).
Reactors under construction:67 reactors totaling 71.2 GW(e) net capacity (PRIS last update: 2026-02-22).
Biggest “nuclear share” country:France at 67.3% of electricity from nuclear (2024).
Global Nuclear Electricity Generation
Global nuclear output hit a new record in 2024. The World Nuclear Performance Report 2025 puts 2024 generation at 2,667 TWh (up from 2,601 TWh in 2023), surpassing the previous record set in 2006.
Chart: Global Nuclear Electricity Generation (Selected Years)
Two commonly used “fleet size” snapshots differ mainly due to definitions (e.g., operable vs in operation, and treatment of units in long outages). The International Energy Agency estimates 420 GW of installed nuclear capacity globally in 2024, while PRIS (IAEA) reports 413 reactors in operation with 377.1 GW(e) net capacity (as of 2026-02-22).
Metric
Value
Reactors in operation (PRIS, last update 2026-02-22)
413
Net capacity in operation (PRIS, last update 2026-02-22)
377.1 GW(e)
Reactors in suspended operation (PRIS, last update 2026-02-22)
23
Reactors under construction (PRIS, last update 2026-02-22)
67
Net capacity under construction (PRIS, last update 2026-02-22)
71.2 GW(e)
Nuclear Share of Electricity by Country
Countries with large nuclear fleets or small grids can show very high nuclear shares. PRIS data for 2024 shows France leading at 67.3%, followed by Slovakia at 60.6%.
Chart: Nuclear Share of Electricity Generation (2024)
Label
Bar
Value
France
67.3%
Slovakia
60.6%
Hungary
47.1%
Belgium
42.2%
Bulgaria
41.6%
Czech Republic
40.2%
Finland
39.1%
Belarus
36.4%
Max = 67.3%. Widths: France 100.00%, Slovakia 90.04%, Hungary 69.99%, Belgium 62.70%, Bulgaria 61.81%, Czech Republic 59.73%, Finland 58.10%, Belarus 54.09%
How Nuclear Fits Into the Power Mix
In 2024, nuclear covered about 9% of global electricity generation. In advanced economies, it can be a much larger slice of the mix—for example, the IEA reports nuclear at about 18% of U.S. electricity generation and about 23% in the European Union in 2024.
Emissions and Climate Impact
On a life-cycle basis (including construction, fuel, operations, and decommissioning), the IPCC’s median estimate commonly cited for nuclear electricity is about 12 gCO2e/kWh—similar to wind and far below fossil generation. In addition, the World Nuclear Performance Report 2025 estimates nuclear generation in 2024 avoided roughly 2.1 billion tonnes of CO2 compared with equivalent coal generation.
Safety Snapshot (Context)
Aggregated comparisons that combine deaths from air pollution and accidents often rank nuclear among the lowest-mortality electricity sources. Our World in Data’s commonly referenced dataset places nuclear at about 0.03 deaths per TWh (air pollution + accidents), though estimates depend on methodology and assumptions about historical accidents.
