Nuclear power plant Temelin in Czech Republic. Europe.


Nuclear power plant Temelin in Czech Republic. Europe.

Temelin Nuclear power plant in Czech Republic

Temelín Nuclear Power Station is located near Temelín, a small village in the Czech Republic. Temelín NPP is owned by ČEZ Group, which employs 1000 workers at this site.

In spring 2003, the Temelín NPP, with its 2,000 MW of installed capacity, became the largest power resource in the Czech Republic.
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The Temelín NPP is situated approximately 24 km away from České Budějovice and 5 km from Týn nad Vltavou. It generates electricity in two units with VVER 1000 pressurized water reactors, type V 320. The first reactor was loaded with fuel in July 2000. Unit 1 generated its first electricity on 21 December 2000. Unit 2 was put into operation in 2002.
The containment building is a massive reinforced concrete structure, 56 metres tall. It consists of a cylinder and a spherical cap. The walls of the cylinder are 1.2 metres thick; the dome structure is just ten centimeters thinner. The inner diameter of the containment is 45 metres. Temelín NPP has unit control room simulator. It used as a training device for operators.

Main coolant pumps
Main coolant pumps, one in each of the four coolant loops, ensure coolant circulation in the primary circuit to remove heat from the reactor to the steam generator. Vertical, centrifugal, single-stage pumps are used, which are located on the cold legs of the primary circuit circulation loops. The pumps are 11.9 m high; their power input is 5.1 MW under rated conditions. The flow rate of one pump is 21,200 m3/hr. under rated conditions. Trouble-free operation is ensured by auxiliary systems (oil treatment plant, seal water, autonomous cooling circuit and washed seals).

Pressurizer
The pressurizer system compensates for volume and pressure variations in primary circuit coolant. The main part of the system is the pressurizer (a vessel 16 m high and 3.5 m in diameter), inseparably connected to the primary circuit. It is filled with two-thirds of primary circuit coolant and one-third of steam. Pressure in the primary circuit is controlled by the pressure of steam in the upper part of the pressurizer. When pressure in the primary circuit drops, electric heaters in the lower part of the pressurizer turn on. This increases the volume of steam in the upper part of the pressurizer and, consequently, pressure in the primary circuit. When pressure in the primary circuit exceeds a predefined level, this activates the sprinkler system in the upper part of the pressurizer. Its operation reduces the volume of steam in the steam part of the pressurizer, which results in reduced pressure in the primary circuit. If the sprinkler system failed to provide the pressure drop needed in the primary circuit, a relief valve and, if necessary, safety valves would open. Steam flows through those valves to the bubble condenser tank, condensing there and, if the safety valves are opened for a prolonged time, passing to collection pools in pressure-tight areas. The pressurizer and the bubble condenser tank are made by VÍTKOVICE.

Fresh nuclear fuel storage
The fresh fuel storage is located in the nuclear auxiliary building. Since nuclear material is stored here, this is one of the most secured buildings on the power plant’s site. Fresh fuel assemblies are stored in special containers. Before they are put into the containers, they are checked visually. In terms of radiation protection, the storage premises are subject to the same rules as the power plant’s controlled area. Since 2010, Russian company TVEL, which won the contract in 2006, replacing US Company Westinghouse after ten years, has delivered fuel for the Temelín NPP.

Spent fuel storage
The spent fuel storage building used to store Castor storage casks. This contain spent fuel that was in the reactor once and has been cooled in the storage pool for ten years.

Turbine building
The turbine building contains the main equipment of the secondary circuit. The most important piece of equipment is the 1,055 MW turbine generator, which consists of a steam turbine, electric generator, exciter and auxiliary exciter. The steam turbine consists of one high-pressure and three low-pressure components. Horizontal separators / steam reheaters are located at both sides of the turbine. A condenser is located underneath each low-pressure turbine component. Other important systems of the secondary circuit include the condensation and recovery systems. After having its voltage raised from 24 kV to 400 kV in transformers, electricity obtained.
The electric generator (turbo-alternator) shares the same shaft with the turbine. After technical modifications made to various parts of the power plant, its power output has been 1,055 MWe since September 2013. Its weight is 564 tonnes; it is cooled by hydrogen and water. The generator rotor has a field winding that creates a magnetic field. Electric current is generated in the stator winding. After having its voltage raised from 24 kV to 400 kV, electricity obtained from the generator is delivered to the grid at the Kočín substation, which is located 2 km south of the power plant.

Condensers
Steam that has passed through the turbine has delivered its energy, lost its temperature and changed into a mix of steam and water that needs to be cooled down to form condensate. This is done in the condenser, which contains almost 32,000 titanium-cooling pipes. Such a high number is required to obtain as big a surface area as possible to condensate steam arriving from the turbine. The steam condensates on the surface of the pipes; third circuit cooling water flows inside and is fed by pumps into the cooling towers. Various systems then increase condensate temperature to 219 °C and this water is then delivered to the steam generator. Here it transforms into steam that is fed back to the turbine.

Cooling towers
The cooling towers are the power plant’s dominant feature, rising up to 155 m. In full operation, they release 413 liters of steam per minute.
The closed circuit between the condensers and the cooling towers with forced water circulation ensured by pumps is called the tertiary cooling circuit. It serves to condensate steam delivered from the turbine. Warm water from condensers (30 °C) is cooled in four hyperboloid, natural draught cooling towers. The condenser cooling water is delivered by pipes to the top of the tower and then sprayed onto fill made of PVC blocks inside the tower. While the water is flowing slowly through the fill, it is cooled by cold air flowing from underneath. Some water evaporates in the process (about 0.3 m3/s per tower). Cooled water from the towers falls in the form of water droplets into the collecting pool below the tower. From there it flows into the pumping station by gravity, then the pumps transport it back into the condensers and from there the heated water is transported back into the towers for cooling.

Last Updated on December 13, 2020