Spain’s Nuclear Safety Council (CSN – Consejo de Seguridad Nuclear) has issued a favourable report backing a licence extension for the Almaraz NPP until June 2030. This technical endorsement marks a pivotal moment in Spain’s ongoing debate over its energy transition and the future of its nuclear fleet.
The regulator’s positive assessment concluded that the facility meets all safety criteria required to operate cleanly and securely for an additional two years. The decision was backed by several operational evaluations. CSN verified the structural integrity and ageing management of the plant’s essential systems and components. It also confirmed that the plant’s planned on-site storage facility is fully equipped to handle used nuclear fuel to 2030.
The approval requires the joint operators – Iberdrola (53%), Endesa (36%), and Naturgy (11%) – to maintain specific minimum staffing levels and fulfil ongoing cybersecurity and equipment modernisation milestones. Almaraz comprises two pressurised water reactors with a net capacity of 1,011 MWe and 1,006 MWe. Unit I began commercial operation in 1983 and unit II in 1984. Almaraz is Spain’s largest nuclear facility, generating more than 7% of total electricity. Keeping it online strengthens grid stability and provides reliable, carbon-free baseload power.
The CSN recommendation disrupts the national phase-out plan agreed upon in 2019, which scheduled Almaraz I to close in late 2027 and unit II in 2028, leading up to a total nuclear shutdown by 2035. However, the board of plant owner/operators (CNAT – Centrales Nucleares Almaraz-Trillo) in October 2025 asked the government to allow Almaraz to remain in service for another two years and requested the opinion of the CSN.
CSN’s report is based on 29 documents prepared by 16 specialist areas of the regulator involved in the process. In addition to these documents, compliance with the conditions and commitments included in the current operating licence has been verified through continuous monitoring and control of the facility by the regulator.
Among the aspects analysed were documentation related to the ageing status of structures, systems, and safety components, the life management plan, and the environmental rating of equipment. The review also examined compliance with the action and improvement plans associated with the periodic safety review for the full 10-year period, which served as the basis for the previous authorisation renewal, currently in effect.
The plant’s used fuel management capacity was assessed up to 2030, and it was concluded that, with the incorporation of the planned ATI-100 storage facility, along with the existing capacity, there is sufficient storage capacity until 2030. Other aspects related to fire protection and human resource management were also analysed.
The final decision rests with the Ministry for Ecological Transition Transition and the Demographic Challenge (MITECO – Ministerio para la Transición Ecológica y el Reto Demográfico), led by Vice-President Sara Aagesen’s team. The government, which must issue its ruling before the end of October, is not obliged to follow the regulator’s recommendation.
Prime Minister Pedro Sanchez’s government has previously said any extension would depend on the plant meeting all required safety standards and not imposing additional costs on taxpayers.
Spain had eight NPPs supplying around 38% of the country’s electricity during the 1980s. It now has five plants with seven reactors – Almaraz I and II, Ascó I and II, Cofrentes, Trillo and Vandellós II – generating about 20% of its electricity. Under the country’s nuclear phase-out plans four reactors are scheduled to close by the end of 2030 – including the two Almaraz ones – while the remaining three reactors will shut by 2035.
The three nuclear power plants that have already closed permanently are: José Cabrera (also known as Zorita), closed in April 2006; Santa María de Garoña, closed in December 2012; and Vandellós I, which was closed in 1990 following a serious fire in 1989 and is currently being dismantled by Enresa. In addition to the Almarez units, Ascó I and Cofrentes are scheduled for 2030. Ascó II, Vandellós II, and Trillo are scheduled to shut down between 2032 and 2035.
The government aims to increase the share of electricity generated by renewables like wind and solar power as it phases out nuclear. However, last year’s nationwide blackout and recent fuel supply disruptions linked to the war in the Middle East have rekindled debate over the phase-out, mirroring a wider reassessment of nuclear power across Europe.
