Today we're going to talk about one of the most important nuclear power plants in Spain. It's the Almaraz Nuclear Power Plant , located in the municipality of Almaraz de Tajo (Cáceres), within the Campo Arañuelo natural region. Its importance lies not only in its capacity to generate large amounts of energy, but also in its role in the Spanish electrical grid since 1981. The land occupied by this plant covers 1683 hectares, also encompassing Saucedilla, Serrejón, and Romangordo. This site was carefully selected due to its optimal seismotectonic, geological, climatological, and hydrological conditions.
Throughout this article, we will analyze in detail the operation of the Almaraz nuclear power plant, addressing key aspects such as its infrastructure, the type of reactors it uses, its cooling system, and its environmental impact. If you want to learn more about nuclear energy and how it is produced in Spain, this article will be very helpful.
The installation of the Almaraz nuclear power plant
The Almaraz nuclear power plant has two pressurized light water reactors (PWRs) with a total thermal output of 2947 MW each. Each reactor has three cooling circuits that ensure its proper operation and safety. Approximately 80% of the plant's construction and design was carried out by Spanish companies, reflecting a significant industrial contribution to the nuclear sector.
Its operation is strictly regulated by the Nuclear Safety Council (CSN) , which guarantees compliance with current safety regulations. Both reactors use slightly enriched uranium oxide as fuel , allowing them to produce electrical outputs of 1049,43 MW and 1044,45 MW, respectively.
As for the ownership of the power plant, it is divided among several companies in the energy sector. Iberdrola Generación Nuclear owns 53%, while Endesa holds 36% and Gas Natural Fenosa Generación the remaining 11%.
One of the key aspects in the design of the facility is its cooling system, which operates through an artificial reservoir known as the Arrocampo Reservoir , created specifically to cool the facilities and ensure their thermal stability.
Heat and fuel generation
The core of each reactor at the Almaraz nuclear power plant is capable of holding approximately 72 tons of uranium oxide enriched with Uranium-235, with an enrichment of around 4,5%. This nuclear fuel, which comes in the form of small cylindrical pellets approximately 8,1 mm in diameter and 9,8 mm long, is grouped inside alloy tubes called zircaloy , which in turn are arranged in bundles of 289 units known as fuel assemblies.
In total, the reactor vessel houses 157 of these fuel elements. However, since uranium is not a renewable resource, and nuclear reactions consume the material, the reactor is refueled by replacing one-third of the fuel elements approximately every 18 months. This process is crucial to ensuring the continuity of energy production.
Comparatively, a single day of operation at this plant is equivalent to the consumption of 68.000 barrels of oil in a fuel-fired plant of similar capacity, or 14.000 tons of coal per day in a thermal power plant. In terms of emissions, it is important to highlight that the Almaraz plant prevents the emission of more than 48 million tons of CO2 per year , thus contributing to the fight against climate change.
Fluids and steam generation
To harness the heat generated in nuclear fission reactions, the Almaraz nuclear power plant uses a primary circuit consisting of the reactor vessel, a pressurizer, and three loops. Each loop includes a steam generator and a main pump. The water circulating through this circuit is demineralized , ensuring that blockages do not occur and that the internal machinery is not affected.
The water in the primary circuit absorbs the heat released during the fission of atoms in the reactor. This heat is then transferred to a second water flow in the steam generator, producing steam that drives the turbines. It is important to note that the two water flows are completely independent , eliminating the risk of contamination.
Finally, the reactor and its cooling circuit are contained within a sealed structure known as the containment building , constructed of 1,4 m thick concrete and lined with 10 mm thick steel. This structure ensures that, in the event of an accident, there will be no release of radioactive material into the environment.
Generation of electricity
The electricity generated at the Almaraz nuclear power plant is similar to that of other nuclear power plants , such as Cofrentes. In the secondary circuit, the steam produced in the generators drives the turbines. These turbines transform thermal energy into mechanical energy , which in turn drives the alternator and generates electricity.
The steam leaving the turbines passes through a condenser, where it is converted back into water. This liquid water is then recirculated back to the steam generator, thus completing the cycle. During this process, several preheating phases are used to optimize the performance of the system.
In total, the Almaraz plant generates 16.000 billion kWh annually , representing a significant portion of Spain's energy production. Thanks to its redundant safety systems, the plant is one of the most efficient and safest in the world, recognized by the World Association of Nuclear Operators (WANO) as a benchmark facility.
In recent years, more than 400 million euros have been invested in modernizing and improving the safety of the plant, which has not only allowed it to meet international standards, but also to optimize its operations for the future.
In addition to its large electricity generation capacity, the Almaraz nuclear power plant directly employs around 800 workers , a figure that rises to 2000 during refueling operations. This makes it one of the main economic drivers of the region.
Thanks to the implementation of new technologies and continuous improvements to its facilities, the Almaraz plant remains a pillar in the generation of nuclear energy in Spain. Its efficient and safe operation places it as a global example in the nuclear industry, and as international experts have stated, its current state is even better than when it was inaugurated more than four decades ago.