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New Builds Aim to Offset Europe’s Aging Nuclear Fleet

Written by Matthew Hoza | Aug 12, 2025

Europe’s nuclear sector is at a crossroads. While much of the continent’s existing nuclear capacity comes from reactors that have been operating for decades, several countries are moving forward with large-scale development plans. However, prolonged delays and escalating costs jeopardize timely additions, forcing greater dependence on an aging fleet.

Europe’s operational nuclear capacity is concentrated in a few countries, with France leading by a wide margin at over 60 GW. Germany, once home to more than 20 GW, closed its final plant in 2023, bringing a 50-year chapter of nuclear generation to a close. Across the region, most reactors are large-baseload units built in the 1970s and 1980s and have played a central role in meeting national electricity demand for decades.

A new wave of planned projects across Europe aims to replace retiring capacity and, in some countries, expand nuclear’s share of the power mix. The UK’s Sizewell C project is among the most high-profile examples, backed by government funding and framed as a cornerstone of the country’s net-zero strategy. Yet its development also illustrates the sector’s persistent hurdles. When EDF submitted its application for the plant in 2020, the plant was estimated to cost £20 billion and begin service in the early 2030s. Five years later, projected costs have surged to £38 billion, and the start of commercial operations has slipped by at least five years. This is a not a rare occurrence, as is shown in the following table of planned units.

These delays come against the backdrop of an aging fleet. In countries like France, the absence of recent new builds means continued reliance on decades-old infrastructure. On the current trajectory, France’s reactors will average nearly 55 years of service by 2040. While new projects will help moderate the overall aging trend, keeping Europe’s average fleet age near 40 years in both 2035 and 2040, this stabilization is driven in part by the retirement of the oldest units. Even with planned additions, Europe’s total nuclear capacity is projected to decline by nearly 15% by 2040, falling to just over 100 GW.

Europe’s nuclear sector stands at a pivotal juncture. Governments face the dual challenge of replacing retiring capacity while managing the cost and schedule risks that have long plagued the industry. The stakes are heightened by rising electricity demand from energy-intensive sectors and projects, such as data centers. This rise in demand is also occurring alongside the ongoing need for energy security, whether from reducing reliance on Russian supply or managing increasing dependence on U.S. LNG, as transatlantic relations remain tense. Without timely replacement capacity, Europe risks deeper dependence on an aging nuclear fleet, leading to higher maintenance costs, more frequent unplanned outages, and growing vulnerability to supply disruptions.

 

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