The age distribution of operating nuclear reactors worldwide concentrates heavily in units commissioned during the buildout decades of the 1970s and 1980s, leaving a large share of global capacity approaching or past original design life assumptions.

That distribution shapes near-term policy far more than new construction does. Every reactor reaching the end of an initial 40 year license period presents operators and regulators with a decision between renewal, uprate investment, or retirement, and the capacity at stake in those decisions exceeds what new projects will add over the same window. Extending an existing reactor preserves output at a fraction of new build capital cost, which explains why license renewal has become the primary mechanism sustaining nuclear generation share in mature markets.

The United States operates 94 reactors totaling 97 gigawatts, the largest fleet globally, with France second at 63 gigawatts and China third at 55 gigawatts. The US fleet skews older than China's, where the majority of units entered service within the past two decades.

Regional generation forecasts show growth concentrated outside North America and Western Europe. Asia-Pacific is projected to add 124 terawatt-hours of nuclear generation in 2026, while Europe adds 58 terawatt-hours over the same period. Those additions come from new construction in the Asia-Pacific case and from restart and uprate activity in Europe.

Source: Visual Capitalist - https://www.visualcapitalist.com/visualized-the-age-distribution-of-nuclear-reactors/