Today we are going to talk about another Spanish nuclear power plant with great relevance in the energy sector. Is about the Almaraz nuclear power plant. It is located in the municipality of Almaraz de Tajo (Cáceres). The lands where it is located have an area of 1683 hectares of land and are located not only in the municipality of Almaraz, but also part of Saucedilla, Serrejón and Romangordo. This place was chosen for the construction of the plant because it has very good seismotectonic, geological, climatological and hydrological characteristics.
In this article we are going to thoroughly analyze the Almaraz nuclear power plant. If you are afraid of nuclear energy and want to know better how nuclear power plants work, this is your post 🙂
The installation of the Almaraz nuclear power plant
This nuclear power plant consists of two 2947 MW thermal pressurized light water reactors. Each of them has three cooling circuits. In its manufacture and construction there is a Spanish contribution to 80%. Its activity is controlled by the Nuclear Safety Council (CSN).
The two light-water reactors use slightly enriched uranium oxide as fuel. This makes its electrical power are 1.049,43 MW and 1.044,45 MW, respectively. The nuclear power plant is owned by 53% by Iberdrola Generación Nuclear, SAU, by Endesa Generación, SAU by 36% and by Gas Natural Fenosa Generación, SLU by 11%.
The cooling circuits are contained in the holding enclosures prepared in each reactor building. The steam that comes from the generators is conducted to the turbine building that houses both turbo-groups in the same room, but independently.
The cooling intake is common in both installations from the cold source. In order to cool the reactor and not overheat the chemical reactions that take place inside the nuclear power plant, the Arrocampo reservoir has been built. This reservoir has been built solely for the cooling of the nuclear power plant.
Heat and fuel generation
The Almaraz nuclear power plant is capable of loading in its reactor about 72 tons of uranium oxide enriched with Uranium 235. This is done at a 4,5% ratio to fine tune the reagents.
The fuel can be seen in the form of cylindrical pellets about 8,1mm in diameter and 9,8mm in length. They are stacked in metal zircaloy alloy tubes just over 4 meters long and 10 mm in diameter. These tubes are also grouped in bundles of about 289 units. They are called fuel elements and are intended for the units to house the fuel rods. The rest are just tubes that also provide rigidity to the structure of the instrumentation and control rods.
The reactor vessel contains a total of 157 fuel elements. So that the reactions do not stop and can generate electrical energy continuously, the reactor has to be recharged periodically. This is done by changing one third of the fuel elements.
To give us an idea, one day of production at this nuclear power plant is equivalent to the consumption of 68.000 barrels of oil in a fuel plant with the same power. If we compare it with a conventional thermal power plant that uses coal as fuel, 14.000 tons of it would be used per day. In this way, the Almaraz nuclear power plant avoids the emission of 48 million tons of CO2 into the atmosphere. This reduction is grateful for global warming and the negative effects of climate change on the world.
Fluids and steam generation
To generate the steam necessary to heat the reactants, there is a primary circuit. It is made up the vessel that has the nucleus, the presser and three loops. Each of the loops has a built-in steam generator and main pump. The water that circulates inside has to be demineralized so as not to obstruct the machinery. As it passes through the interior it takes in the heat that is produced in the heat resulting from the Nuclear fision and transports it to the steam generator.
Once in it, the second flow of water is responsible for absorbing the heat from the pipes through which the previous demineralized water circulates. Both fluids are independent of each other. It could be said that the first flow of water is responsible for absorbing the heat of the reaction and this second flow of cooling the first. All this helps to avoid overheating.
The reactor and its cooling circuit are contained within a hermetic and watertight enclosure, called «Containment», consisting of a cylindrical concrete structure 1,4 m thick on its lateral surface and with a 10 mm thick steel coating. The support of the concrete structure has a thickness of 3,5 m.
The containment has an upper closure that is shaped like a hemispherical dome. The operation of the primary circuit is complemented by various auxiliary systems. These systems have a vital function so that there are no accidents. It is about ensuring the volume, purification and degassing of the refrigerant. For this it has a good chemical control and the treatment of solid, liquid and gaseous waste. It also has other functions necessary for the operation to be correct.
Generation of electricity
Finally we come to the last part where the Almaraz nuclear power plant generates electricity. Its operation is similar to other nuclear power plants such as that of Cofrentes. In the secondary circuit, the steam produced in the generators is conducted to the cold source through a turbine. This turbine is responsible for transforming thermal energy into mechanical energy.
Rotation of turbine blades drives the central alternator directly and produces electrical energy. The water vapor that comes out of the turbine becomes liquid in the condenser, returning, through the help of the condensate and feed water pumps, to the steam generator to restart the cycle. Several preheating processes are incorporated in this phase to help optimize thermodynamic performance. Direct conduction (by-pass) is responsible for conducting the steam from the inlet to the high pressure turbine to the condenser.
With this information you will be able to know in depth the operation of the Almaraz nuclear power plant.