Ageing Nuclear Reactors Could Stall Global Energy Expansion: IAEA
The IAEA warns that an ageing global nuclear fleet complicates capacity expansion as nations balance new builds with old plant maintenance.
The world's ambition to expand nuclear power capacity is facing a significant hurdle: a fleet of ageing reactors. According to the International Atomic Energy Agency's (IAEA) Nuclear Technology Review 2026, countries are now caught in a difficult balancing act, needing to invest heavily in extending the lives of old plants while simultaneously funding the construction of new ones to meet surging electricity demands.
The Weight of an Ageing Fleet
The scale of the ageing infrastructure is stark. The IAEA report reveals that a vast majority of the world's nuclear power capacity is well past its initial design milestones. Specifically, about 67% of global nuclear power capacity—comprising 293 reactors totaling 263.9 GW(e)—has been operational for over 30 years.
Even more concerning is the number of plants reaching extreme age; 41% of the capacity (190 reactors, 135.5 GW(e)) has been running for more than 40 years. This means that future growth in nuclear energy will not just be about building the next generation of plants, but about whether existing plants can be safely maintained or if they must be retired.
Stability Amidst Transition
Despite the age of the infrastructure, the global nuclear sector has shown remarkable resilience. The IAEA noted that nuclear power performance remained strong, with a global load factor reaching 93% in 2025.
Over the last decade, the total global capacity has remained relatively stable, moving from 370.2 gigawatts in 2016 to 379.9 gigawatts in 2025. This stability is a result of a constant tug-of-war between new additions and permanent closures. While 60 new reactors (adding 61.4 gigawatts) were connected to grids during this period, a growing number of facilities were shut down.
The Decommissioning Dilemma
As plants reach the end of their operational lives, the process of shutting them down becomes a logistical and financial burden. By the end of 2025, 218 power reactors across 21 Member States were shut down for decommissioning, with 23 units having been fully decommissioned.
The IAEA highlighted that this process is not equally easy for everyone. Countries with limited financial and technical resources are struggling to execute effective decommissioning strategies, creating a bottleneck in the transition to newer energy systems.
The Road Ahead: New Builds and Big Hurdles
While old plants are closing, the appetite for nuclear energy remains high. As of late 2025, 72 reactors with a combined capacity of 77.2 gigawatts were under construction across 15 different countries.
However, the path to a nuclear-powered future is fraught with challenges. The IAEA identified three primary obstacles that could slow down this expansion:
- Financing: Securing the massive upfront capital required for nuclear projects.
- Cost Reduction: The need to lower the overall project costs to make nuclear power more competitive.
- Regulatory Standardisation: The lack of uniform global standards which can complicate the rollout of new technology.
Ultimately, the IAEA warns that the success of global energy security will depend on how well nations manage the "double burden" of funding cutting-edge new reactors while paying for the refurbishment and safe retirement of the aging giants that currently power the world.