Spain is burning and its nuclear power plants notice it. This is your strategy to endure

Spain is sweating again. extreme temperatures At the end of June, alarm bells have gone off in a good part of the country, and the Spanish nuclear park, responsible for about 20% of electricity what we consume, is not alien to this phenomenon. However, it is worth clarifying something from the beginning: whether a plant reduces its power or stops during a heat wave has nothing to do with a security failure.

The seven nuclear reactors in operation in Spain (Almaraz I and II, Ascó I and II, Cofrentes, Trillo and Vandellós II) have been dealing with demanding summers for several decades, and their cooling systems were designed precisely with scenarios like this in mind. The Nuclear Safety Council publishes in real time the operational status of each plant, so anyone can check how they are responding.

The key is in the external cooling circuitresponsible for evacuating the heat dissipated by the electricity generation process into the environment. In pressurized water plants, such as Almaraz, Ascó and Vandellós II, this circuit is the third in the installation, independent of the primary (which surrounds the core) and the secondary (which moves the turbine). Cofrentes, the only Spanish plant with a boiling water reactor, has a different architecture, a direct cycle, but it also depends on that same external circuit to cool the condenser. And this is where each plant plays its own cards depending on its geographical location.

Three ways to beat the heat

Ascó I and II, Cofrentes and Trillo are fed by river water, but they do not return it directly to the riverbed after using it. First, it passes by the cooling towers, those structures more than 160 meters high that we have described so many times when explaining the internal workings of a nuclear power plantand that dissipate heat into the air by convection and evaporation before any pouring. This drastically reduces the amount of water they need to extract from the river, up to twenty or thirty times less than if they did not have that tower.

Almaraz represents a particular case because it does not depend on the flow of a natural river. It uses the artificial Arrocampo reservoir, conceived as a closed system that acts as a large heat exchanger. This independence of the river regime allows it continue operating normally even when temperatures soar, something especially relevant in a plant that will be the first to shut down: Almaraz I will close in November 2027 according to the current government calendar.

Vandellós II draws on another resource: the water of the Mediterranean. The sea has a thermal stability much greater than that of a river, so it absorbs heat without its temperature rising appreciably. And, what’s more, it varies much less during heat waves. It is the same thermodynamic logic that explains why so many power plants in the world, from those that are cooled with seawater to those that use closed circuits like the one in Almaraz, prioritize the thermal stability of the cold source over any other consideration.

When safety forces you to stop

What can happen, and in fact happens quite frequently during the strictest summers, is that a nuclear power plant reduces its power or stops temporarily. The reason is not to protect the reactor, but the aquatic ecosystem. And the regulations limit the temperature at which water can be returned to a river or the sea, and if these limits are close to being exceeded, the facility prefers to slow down rather than breach them. It is an environmental decision, not a safety emergency.

Meanwhile, the clock of the Spanish nuclear blackout continues to tick in parallel to these episodes of extreme heat. The current calendar starts in 2027 with Almaraz I, followed by Almaraz II in 2028. In 2030 it will be the turn of Ascó I and Cofrentes; Ascó II will close in 2032; and The process will be closed in 2035 with Vandellós II and Trillo, the last two plants to go out. Until then, each summer will be another test of resistance for a park that continues to provide a fifth of the national electricity.

Image | Nuclear Forum

More information | Nuclear Forum

In Xataka | SMR reactors are going to make the never seen a reality: the first floating nuclear power plants