Lorraine Williamson
Spain’s nuclear waste storage has quietly become one of the most consequential questions hanging over the country’s energy transition. As reactor closures begin to edge closer, the issue is no longer abstract. It is about where high-level waste will sit, who will pay, and how Spain avoids leaving a long-term hazard on short-term political life support.
The government’s direction of travel is now clearer than it has been for years. Instead of pursuing a single “one-size-fits-all” store, Spain is moving towards interim storage at each nuclear site, while developing the legal and technical pathway to a deep geological repository for the most hazardous waste.
The big shift: no single national store in Cuenca
For more than a decade, Villar de Cañas (Cuenca) was the intended home of a centralised temporary storage facility. That route has been formally scrapped. A government decision left the 2011 site designation without effect, aligning the strategy with the current national radioactive waste plan.
In practice, this locks Spain into a decentralised approach for the coming decades: waste stays where it is produced, at least for the interim phase. It also reflects a political reality that has shaped nuclear policy across Europe. Finding one community willing to host everyone else’s waste can be harder than the engineering.
Interim storage at nuclear plants becomes the default
Until a permanent facility exists, Spain’s spent fuel and high-activity waste will remain at or beside existing power stations in dedicated on-site installations. This isn’t unusual internationally, and Spain already has multiple “ATI” (individualised interim storage) facilities operating or being expanded under nuclear regulator oversight.
The safety regime matters here. Spain’s regulatory framework for nuclear and radioactive facilities explicitly builds in long-term safety analysis, closure planning, and post-closure monitoring requirements for any definitive storage installations that may follow.
The endgame: a deep geological repository
The long-term solution on the table is a deep geological repository: high-level waste stored far underground in stable rock, designed to remain safe over timescales far beyond a human lifetime. It is the model many countries treat as the most credible route for permanent disposal, because it aims to minimise reliance on active monitoring in the far future.
Spain’s own planning documents set this as the final destination for spent fuel and high-level waste. But “final” does not mean “soon”. Even in countries furthest along, deep geological programmes have taken decades from political decision to operation.
Why this is landing now: closures start in 2027, debate is heating up
Spain’s nuclear phase-out timetable still points to the first shutdown in 2027, with the fleet scheduled to close by 2035. That makes waste policy urgent, because radioactive material outlives the power stations that produced it.
At the same time, the politics are shifting. In late 2025, major utilities signalled interest in extending the life of Almaraz, arguing about security of supply and system stability. Even if the closure calendar changes, the waste question does not go away. It simply stretches further into the future.
What it means for the public, and for towns near nuclear sites
For communities near existing plants, decentralised interim storage is a double-edged decision. It reduces transport movements across Spain, but it also means host areas remain the front line of waste management for longer. That is why transparency, local monitoring, and clear responsibility lines matter as much as engineering detail.
For the wider public, the stakes are simple. High-level radioactive waste demands policy that can survive election cycles, and a regulator that can enforce safeguards long after today’s ministers are out of office. Spain is now trying to anchor that reality into a strategy built for decades, not headlines.
Galicia´s long buried nuclear legacy
The decision Spain still has to make
Interim storage buys time, not a finish line. The hardest step is still ahead: choosing a process, and eventually a place, for a deep geological repository that can command scientific confidence and public legitimacy. Until that happens, Spain’s nuclear waste will remain exactly where it already is — quietly accumulating, and steadily shaping the country’s energy choices.
Sources: