In 2025, 3 GW of new nuclear capacity came online, with China, India and Russia each completing work on a new reactor. However, these additions were offset by the retirement of 3 GW of nuclear capacity, two-thirds of which was in Belgium. In total, global nuclear capacity remained at 420 GW at the end of 2025, with reactors in operation in over 30 countries. There were ten construction starts in 2025 – nine in China and one in Russia – with a total capacity of 12.2 GW. Over the past decade, 94% of nuclear reactors that started construction were of Chinese or Russian design.

The capacity of nuclear reactors under construction is one of the highest levels seen in the last 30 years

Nuclear reactors with a combined capacity of 78 GW are currently under construction in 15 countries. Half of capacity under construction globally is in China, with total installed capacity in the country expected to reach 100 GW by around 2030. Among other emerging market and developing economies, Egypt, India and Türkiye each have around 5 GW under construction. In advanced economies, Japan, Korea and the United Kingdom each have two reactors under construction, while Slovakia has one; their combined capacity is 9.5 GW. Japan continues to restart reactors whose operations had been suspended.

Nearly all nuclear reactors currently under construction are large scale, most with capacities above 1 000 MW. At the same time, China already operates one land-based small modular reactor (SMR), and Russia a marine-based one. There is one 125 MW commercial SMR under construction in China and one with 300 MW of capacity in Russia. Additional SMRs are likely to begin construction in the near term in Canada, Korea, the United Kingdom and the United States.