There are currently 74 nuclear reactors under construction in 15 countries (Table 1, World Nuclear Association 2026a). There are an additional 121 nuclear reactors in the planning stage in 17 countries (Table 2). These projects have received approval and funding, and are expected to be in operation within the next 15 years (World Nuclear Association 2026b).
About two-thirds of reactors that are planned or under construction are designed to generate over 1000 megawatts electrical (MWe) of power. Some countries are also building small modular reactors (SMRs). These are a class of nuclear reactor designed for smaller power generation, faster assembly, and lower construction costs (World Nuclear Association 2025, International Atomic Energy Agency n.d.). SMRs generate up to 300 MWe, though some definitions include reactors that generate up to 600 MWe.
The nuclear reactors under construction have four different designs (World Nuclear Association 2021, World Nuclear Association n.d.). Boiling water reactors (BWR) use a single water circuit for steam generation. Pressurized water reactors (PWR) have a second water circuit for cooling and are the most common type of reactor. Pressurized heavy water reactors (PWHR) are similar to PWRs but use deuterium oxide, also called heavy water, for cooling. Fast breeder reactors (FBR) generate more fissile material than they consume, which can be reprocessed into new nuclear fuel.
Table 1. Nuclear reactor projects currently under construction. Countries in gold have no nuclear reactors currently operating. Data compiled from World Nuclear Association 2026a in January 2026.
Table 2. Planned nuclear reactor projects. Countries in gold have no nuclear reactors currently operating. Data compiled from World Nuclear Association 2026a in January 2026.
References:
International Atomic Energy Agency (n.d.) Small modular reactors (SMRs). https://www.iaea.org/topics/small-modular-reactors
World Nuclear Association (n.d.) Are there different types of reactor? https://world-nuclear.org/nuclear-essentials/are-there-different-types-of-reactor
World Nuclear Association (2021) Fast neutron reactors. https://world-nuclear.org/information-library/current-and-future-generation/fast-neutron-reactors
World Nuclear Association (2025) Small modular reactors. https://world-nuclear.org/information-library/nuclear-power-reactors/small-modular-reactors/small-modular-reactors
World Nuclear Association (2026a) Plans for new reactors worldwide. https://world-nuclear.org/information-library/current-and-future-generation/plans-for-new-reactors-worldwide
World Nuclear Association (2026b) Definitions of capacity categories. https://world-nuclear.org/our-association/publications/world-nuclear-outlook-report/definitions-of-capacity-categories
