The World Nuclear Association warns that new nuclear reactor construction must increase fivefold by the late 2030s to meet 2050 targets of 1,457GW total capacity. Currently, only 12.6GW started construction in 2025, far below the required 60-65GW annually. Jonathan Cobb, senior programme lead for climate at the WNA, stressed that "concerted action" on supply chains, workforces, and regulation is needed this decade. The warning comes as London hosts the 51st World Nuclear Symposium.

China leads recent construction starts, while the UK builds Hinkley Point C in Somerset and Sizewell C in Suffolk using French technology. Interest in nuclear has grown amid the US-Iran war and fossil fuel volatility, with Brazil and China joining a COP28 pledge to triple capacity to 1,200GW by 2050.

However, nuclear faces high costs, long lead times, and competition from renewables. In 2025, only 3GW of nuclear came online versus 814GW of solar and wind and 108GW of batteries. Storage growth particularly threatens nuclear's key advantage: reliable low-carbon power regardless of weather. Cobb argued batteries could complement nuclear by allowing plants to run at steadier rates.