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Dukovany Nuclear Power Plant Aerial view

The Dukovany Nuclear Power Plant is the first nuclear power station in the Czech Republic. It ranks among the CEZ, a. s. largest, highly reliable and economically favourable energy resources. The annual electrical energy production is more than 15 TWh which represents approx. 20% of the overall electric energy consumption of the Czech Republic. As compared to other significant resources, the Dukovany power plant produces electricity with the lower specific cost.

Třebíč region's bird's eye view

The panorama of the Dukovany power plant is, simultaneously, also a small flight over the Třebíč region. The town of Třebíč itself, having been inscribed in the UNESCO World Heritage List thanks to its Jewish quarter and the St. Procopius basilica, is slightly visible in the north-west azimuth less than 20 kilometres far. However, a more scenic landscape element is within the stone's cast in the north and north-east direction - the "Dalešice hydro-engineering structure" whose water level appears in meanders. The Dalešice hydro-engineering structure includes the Dalešice pumped-storage power plant, the Mohelno water flow power plant, the Dalešice reservoir, and the Mohelno equalising reservoir used by the Dukovany Nuclear Power Plant for its service purposes. The Dalešice and Mohelno power stations serve, at the same time, as the reserve for situations when there is the loss of mains voltage and the need for black-starting the Dukovany power plant. The hills behind the township village of Mohelno include one of the local unique locations - the Mohelno serpentine steppe - that have been enjoying the status of nature reserve since 1933. Serpentine, as a strongly basic dark-green or black-green rock, accumulates heat quite well. Then, the Zelený kopec (491 m ASL) with the Babylon 42 metres high view-tower from 19th century rises above both locations. Westward, we can find the town of Hrotovice with a minor baroque chateau, and the village of Rouchovany with the Olešná pond south-eastward. The greenery belt southward is the Rokytná natural park with a small river of the same name flowing through forest nooks and corners. The eastward view leads our sights to the villages of Horní and Dolní Dubňany; then, on the horizon, to the region round the town of Moravský Krumlov.

Dukovany Nuclear Power Plant zone and history

Four pressurised water VVER 440/213 type reactors are installed in the Dukovany Nuclear Power Plant; these reactors are cooled and moderated by a specially purified water. Each of the four reactors has the heat power of 1,444 MW which corresponds to the electric power of 510 MW.

The power plant is arranged into two principal production double-blocks. To each of these blocks, two reactors, four turbines with generators, four cooling towers, and other equipment needed for electricity production, belong.

In the Dukovany Nuclear Power Plant zone, there are three separate sets of nuclear equipment: The first includes four reactors, the other represents the spent nuclear fuel storages, and the third nuclear equipment includes the repository of low and medium radioactive wastes owned by the SÚRAO (Radioactive Waste Repository Authority) state organisation.

The history of the Dukovany Nuclear Power Plant goes back to the early 1970s when then Czechoslovakia and the Soviet Union signed an intergovernmental agreement on the construction of two nuclear power blocks with the overall capacity of 1,760 MW.

The Dukovany first reactor block's service was commenced in May 1985, the second and third in 1986, and the last fourth block in July 1987. Thus, the power plant reached the maximum planned power of 1,760 MW. The operation commencement of two nuclear blocks - the second and third - in one single year in one single location was well unique in the world and did not repeat so far. More than 80% of the used installations were made in the Czech Republic.

Since 1985 to September 2014, the power plant produced more than 375 billion kWh of electric energy which is the most of all power plants in the Czech Republic.

Power plant main entrance

In the building on the right-hand side of the main entrance to the power plant, there is the information centre for both the laic and technical public.

Area behind the power plant main entrance

This area is the so-called "safeguarded power plant's entrance" zone into which only the persons that fulfilled conditions needed for issuance their own entrance card, provided the needed data, passed the thorough physical security inspection, and enter the plant escorted by authorised persons, can get into. The entrance to the power plant is only permitted to persons older than 15 years of age. Also subject to inspection in the entrance gate area are all motor vehicles that are entering or leaving the power plant.

The view of the administration building, which is joined together with the first double-block turbine hall via a walkway bridge.

Electric power outlet

On the northern side of the power plant, eight 400 kV power lines are used for letting out the electric power of 2,000 MW. Each of eight 250 MW turbo-generators has its own transformer. The produced electricity is taken off the power plant to the Slavětice distribution point. On the contrary, the reserve supply is taken to the power plant from two directions, Oslavany and Slavětice, via 110 kV power lines.


The Dukovany Nuclear Power Plant also has three smokestacks; however, no smoke ever comes from them. These are two ventilation smokestacks at the reactor buildings that collect air masses from the controlled zone, i.e. from the rooms where a higher level of radioactivity can occur. When these air masses meet the permitted limits for gas outlets, they pass via the ventilation smokestacks into the atmosphere. The controlled discharge of gas outlets is ensured by the vacuum in the ventilation system. The third smokestack belongs to the former boiler plant that has only been operated during the power plant development and used for generating the heat needed for preheating the technologies prior the block start-up.

Low and medium radioactive wastes repository

This is one of four radioactive wastes repositories located in the Czech Republic territory. This one is the largest and corresponds with its design and safety to repositories in the Western European countries. It has been in permanent operation since 1995. The repository is overground and consists of 112 well-separated armour concrete receivers. The overall capacity of repository areas is 55,000 cu. m (about 180,000 barrels with the capacity of 200 litres) and is enough for reposition of all radioactive wastes from the Dukovany NPP and the Temelín NPP not only for their service life. All the wastes repositioned here must meet the conditions of the acceptability for repository. The solid as well as liquid wastes are stored here. The solid waste, such as contaminated personal protection equipment, cleaning fabrics, packing and electric wiring materials and others, are pressed in barrels. The liquid waste is also stored in barrels once it has passed through the bituminous line. Up to five filled barrels are pressed again with a large press into one 200 litre barrel. The volume of the low and medium radioactive wastes produced by both nuclear plants is very low. Each capacity-filled receiver in the repository is then cast with concrete, covered with concrete slabs and covered later on by soil and sowed with grass. The low and medium radioactive wastes degrade in about 300 years. Then, the repository can even be cleared in maps because it is no longer dangerous.

Now, the three quarters of the repository's capacity is filled up. The repository has also been designed to accept even the low and medium radioactive sections of the Dukovany and Temelín power plant after their operation is terminated.

Area between cooling towers

Four cooling tower in the western section of the power plant zone are primarily designed for cooling heated water from the first double-block. They can be interconnected with the cooling system of eastern towers. Each of the cooling towers has a pool underneath. Towers' parameters: Height 125 m; diameters from beneath: 90, 56 and 60 m. Pool's parameters: diameter 90 m; depth 2.8 m.

In the cooling tower

The cooling tower is part of the production block tertiary circuit. This is a subtle armoured concrete structure in the form of rotary hyperboloid. It serves for providing an air draft sufficient for cooling the tertiary circuit water. The task of the tertiary circuit is not only to take heat from steam that revved up the turbine in condensers, but also to create in them as large as possible underpressure so that the effectiveness of turbines is as high as possible. The lower the temperature of cooling water in the tertiary circuit, the higher the negative pressure in the condenser. Other pieces of equipment in this circuit covers circulating pumps, pipe lines, and cooling water channels. In the cooling tower's bottom, there is a round pool in which the cooled water collects and is fed by pumps back to the turbines' condenser.

The photo also depicts the cooling tower in which the inner built-in units are being currently replaced to provide another decades of reliable operation. The original wooden built-in units were good for 28 years and are replaced with composite ones that should be good at least for 30 years to come.

In principle, the built-ins represent a jalousie system on which water drops stick and then run down. The built-ins thus prevent water drops from flying away and getting lost in the surroundings. Under the tower's jalousie system, there are water overflows from which water heated in the turbines' condensers rains down. The cold air from the surroundings streams from beneath against the water. Thanks to this, the so-called "stack effect" occurs that keeps an intensive continual circulation within towers.

For the 100% power, the power plant needs 1.2 cu. m of water per second. Thus, each of eight towers evaporates 150 litres per second.

Central pumping station

The nuclear power plant operation depends on large volumes of water that is used for technology purposes. The water management ensures not only the supply of raw water from the Dalešice reservoir, its purification to the required quality and refilling individual circuits, but also collection of individual kinds of wastewater, its treatment and purification, and organised discharging back.

Central pumping station - lower floor

Two central pumping stations are located in the Dukovany Nuclear Power Plant. Each of them serves one double-block by means of pumps located in it; these pumps transfer the circulation cooling water, technical water important and unimportant, and pumps for supplying fire extinguishing water. The output of one circulation pump is 38,000 - 50,000 cu. m per hour at the pressure of 0.35 MPa at the delivery. The regulation is done by turning the impeller blades in the range of 0 to 9 grades.

Dining facility

C. 1,400 lunch meals are provided in a regular working day. The fried schnitzel is the absolutely most favourite meal. However, the power plant staff may enjoy goulash in the most various forms to which c. four thousand of dumplings are provided, i.e. approximately 400 dumpling rolls.

64 persons in total, i.e. 5.5% of all the power plant staff, provide alimentation for the Dukovany power plant staff.

Turbine hall - top view

Two reactor blocks have their common turbine hall with four turbines with the power of 255 MW each. The turbine and the generator are on the common shaft are rotate with speed of 3,000 RPM. In the turbine hall, condensers are located beneath turbines; the steam after turning the turbine on is cooled and condensate in these condensers. Further, there are e.g. the low and high pressure regeneration heaters or condensate pumps in the condensers.

Secondary circuit

The system of equipment allowing transformation of the thermal energy into the mechanical turning energy is called the secondary circuit in the nuclear power plant. The basic devices in this circuit are as follows: the turbine, condenser, condensate and fee pumps, and regeneration heaters.


The condenser server for cooling the steam that turned on the turbine. It is located in turbine's bottom section where it adjoins closely the turbine's low pressure sections. The steam leaving the turbine passes among pipes through which the tertiary circuit cooling water flows, and the steam condenses on the surface of the pipes. The condensed steam (condensate) is transferred by condensate pumps through the condensate treatment, regeneration exchangers, feed tanks and degassers back into the steam generators.

Turbine hall between blocks - +9.6 m

Turbine and generator

The turbine is the rotary thermal machine in which the inner energy of steam is transformed into the mechanical turning energy of the turbine's rotor. In impulse turbines, the steam pressure gradient is transformed in the stator blades into the kinetic steam energy that is transferred by means of the rotor moving blades. The turbine's rotor is connected with the common shaft with the generator's rotor in which the rotor's kinetic energy is transformed into the electric energy.

Turbine hall

Condensate and feed pumps

The condensate pumps serve for pumping the condensate from the turbines' condensers through the low pressure regeneration heaters into the feeding tank with degassers. From here, the feed pumps transfer the degassed feed water through the high pressure regeneration heaters into the steam generators and, at the same time, they increase the pressure of the degasses water to the generated steam pressure.

Low and high pressure regeneration heaters

These are the heat exchangers in which the steam from unregulated steam extractions renders its condensation heat to the condensate of the feed water of steam generators. In the low pressure regeneration exchanger, the condensate is gradually heated so that it can be, after passing through the feed tank and degassers, relieved of gases contained in it. In the high pressure regeneration heaters, the degassed feed water is additionally heated and the returned back into the steam generators.

Turbine hall - 0 m

In this part of the turbine hall, there are auxiliary systems of the turbine-generator unit and the secondary circuit, such as the condensate block treatment. Also devices located even lower are present in the turbine hall.

Primary steam collector area - +14.7 m

Each double-block of the Dukovany Nuclear Power Plant has one primary steam collector that is divided into individual blocks. Steam from secondary steam generators is taken into the primary collector.

The primary steam collector is equipped with relief valves into the atmosphere whose task is to discharge a volume of steam into the atmosphere and, thus, to reduce the steam pressure in case it rises abruptly. The most important task of the primary steam collector is to take steam from steam generators into the high-pressure sections of the steam turbine. Upstream of quick-closing and control valves, the relief station valves into the condenser are connected; these valves discharge a volume of steam into the primary condenser in case the pressure rises abruptly. However, they are also active when the turbine is shut down (e.g. when the reactor is shut down).

Controlled area access

In the Dukovany Nuclear Power Plant, the controlled area comprises the locations where radioactive substances (or other sources of ionising radiation) are handled, and where the regimen of protecting persons against the ionising radiation must be strictly adhered to. Every person entering the controlled area must pass through the hygiene station where he/she puts on the special clothing designed for moving in the controlled area and, further, he/she must equip him/herself with the personal dosimeter. When leaving the controlled area, the person must surrender the dosimeter, pass through the dosimetric inspection and, again, pass the hygiene station.

Controlled area corridor

The controlled area is not only the set of buildings, reactors or buildings where the radioactive waste generated by the power plant operation is sorted and processed, but also the system of corridors where full-, semi- and non-service places are situated with the primary circuit equipment.

Fresh nuclear fuel node

The area in the reactor hall in which fresh fuel cartridges are stored and subject to inspection once transported to the power plant and then stored there until they are taken into the reactor.

Once a year, during the shutdown, a part of fuel is replaced for the fresh one. In the Dukovany reactors, this amounts to c. one fifth of the fuel - i.e. 72 cartridges. The fuel packages are hexagonal and more than 2.5 m long The supply of the stored fuel will suffice for the reactor for several years.

Reactor hall

The reactor hall is the place where two reactors are situated in reactor wells. Their round lids can be seen on the opposite sides of the reactor hall on the so-called "postaments". In the reactor wells vicinity, other two wells are situated. The one closer to the reactor is the spent fuel pool, and in the last well, either a CASTOR container for the spent fuel if the fuel is transferred from the basin to the spent fuel storage, or a receiver with the fresh fuel if the fuel is replenished in the reactor's active zone, is placed. At the time of shutdown for replacing the fuel in the reactor, the lids from the reactor's well and the spent fuel pool must be removed first. Then, the gate stoppers separating individual wells during operation are removed, inner built-in units taken from the reactor, and all three wells on the postament filled with water along with boric acid. One of the tasks of this water is to shield the personnel from the fuel radioactive radiation. All handling with the fuel is done by means of a special machine called the fuel loader. This machine can be seen on the right rear under the portal crane. The fuel loader is one of the devices used for both reactors. You can further notice two large portal cranes located under the building's roof. They can move over the whole reactor hall and be used for handling heavy equipment, e.g. CASTOR containers for the spent fuel.


If we want to operate the power plant as long as possible and, primarily, safely, its individual sections must be modernized and replaced routinely. Each device needs something specific. For instance, pumps, piping, electric sections and regulators are subject to replacement once in ten years. Electronics are good for c. 15 to 20 years and then are replaced with more advanced ones. The building themselves are good for more than 100 years and the reactor that cannot be replaced, for 70 to 80 years. Thus, large components determine the actual service life of the power plant. The equipment modernization is also the opportunity for enhancing the electricity production efficiency. This has happened in Dukovany in the period 2005 to 2012 when the power output of individual blocks increased from 440 MW to 510 MW.

Barbotage containment

Each block in the Dukovany Nuclear Power Plant has several barriers against leakage of radioactive substance into the plant's shops and its surrounding in case of disaster. The first two barriers is represented by the fuel tightness and the fuel covering, the other by hermetic boxes, and the barbotage containment is the last barrier. The barbotage container serves for reducing the overpressure of the radioactive steam in case the largest projected disaster, i.e. the burst of the cooling water piping in the primary circuit, happens. First, the radioactive steam will be cooled when still in hermetic boxes by means of the shower system, and then it will get into troughs filled with water and boric acid in the barbotage. Rare gases would be captured at the same place in gas holders. Thus, the overpressure will be suppressed and the entire radioactivity captured in the containment.

There are hydrogen recombiners in hermetic boxes that prevent hydrogen accumulation by its peaceful "burning" on platinum catalysers and, thus, prevent it from exploding. Hydrogen is explosive in the air already at the 4% concentration. However, recombiners are able to dispose of hydrogen already at its minimum concentration.

Reactor hall 1

Nuclear reactor

The reactor is the "hart" of the nuclear power plant's primary circuit and needs for its operation primarily the nuclear fuel, coolant, moderator and control systems. The reactor consists of a pressure vessel equipped with the removable lid where the active zone is situated in which the nuclear fuel (enriched uranium containing almost 4.5% of the U235 isotope) and the system for controlling the fission reaction are arranged. The reactor's active zone comprises not only 312 fuel cartridges each of them consisting of 126 fuel sticks with hermetically encased fuel, but also 37 regulation cartridges with the fuel part. The height of the active zone is 2.5 m, diameter 2.88 m. The fuel charge in one reactor weighs 42 tons. The energy released from the nuclear fission is transformed into the thermal energy in the pressurised-water reactor by means of slow neutrons. When the U235 atom encounters a slow neutron, it is fissured to 2 atoms of lighter elements and 2 to 3 fast neutrons. Simultaneously, the energy in the form of gamma radiation and heat is released. However, fission generates only fast neutrons. If they are to induce further fission, their energy must be lowered. The moderator (cooling water surrounding the fuel under the pressure of 12.25 MPa) makes for the deceleration. For regulating (increasing and decreasing) the reactor's power output, regulation cartridges containing a substance (boron) are used. As long as the regulating cartridge is lowered into the bottom position, the part absorbing neutrons is in the active zone and the power output is being decreased. When the cartridge is being pulled out, its bottom half containing the nuclear fuel is put gradually in the active zone and, thus, the power output is being increased.

Reactor hall 2

Loading machine

One fifth of fuel cartridges is replaced in the reactor every year. During shutdown, once the lids from the reactor's wells and the spent fuel pool on the postament are removed, the reactor is opened, its built-in units, gate stoppers between wells removed, its wells filled with water and boric acid, the special loading machine is moved above the reactor. With its telescopic arm, this machine removes from the active zone in sequence one fifth of spent fuel cartridges, rearranges the remaining ones, and loads the fresh fuel from the receiver into the released locations. All is done following the predetermined plan. The spent fuel cartridges are stored in the spent fuel pool beside the reactor. Supervising commissars then verify the fuel replacement completion. Starting 2015, the Dukovany reactors will commence the six-year fuel cycle.

Primary circuit

The primary circuit in the Dukovany Nuclear Power Plant consists of one reactor and six circulation loops. Each loop comprises circulation piping (hot and cold branch), the main circulation pump, and the steam generator. One of the six loops is additionally equipped with the volume compensator. The primary circuit cooling water dissipates the heat generated in the reactor by fission via forced circulation (using pumps) into the steam generator. Here, it transmits the heat through the heat exchange surface to the secondary circuit water, and returns back into the reactor. Thus, it is a closed circuit.

Main circulation pump

The main circulation pump is located in the cold branch of the circulation loop and makes for the coolant circulation through the secondary circuit in the volume corresponding to the reactor's power output. In terms of its design, it is a vertical centrifugal gland pump driven by an asynchronous electric motor.

Volume compensator (pressuriser)

The volume of the coolant in the primary circuit is represented by several hundreds of cubic metres; therefore, it is necessary to count with the thermal expansion of water when heated. The volume compensator is a vertical pressure vessel comparable in its size with the reactor's pressure vessel connected with piping to the hot branch of one of the primary circuit loops. In addition to compensating thermal volume changes of the coolant, the volume compensator also serves for regulating the primary coolant pressure using built-in electric heaters or showers. The volume compensator is equipped with safety valves protecting against excess of the permitted value of pressure in the primary circuit.

Steam generator

The pressure horizontal heat exchanger containing the primary circuit water (flowing in pressure piping of the steam generator) transmits its heat to the secondary circuit water. As the primary circuit water temperature is higher than the secondary circuit water boiling temperature (the water pressure in the primary circuit is more than two times higher than the pressure of water or steam in the secondary circuit), intensive development of steam occurs in the steam generator; this steam is taken to the turbine through steam piping.

Primary circuit circulation loops piping

In each circulation loop, piping 500 millimetres in diameter and the wall 32 mm thick connects the reactor with the steam generator. The section of piping between the reactor and the steam generator through which the heated water from the reactor flows into the steam generator is called the hot branch. The second section of piping taking water from the steam generator through the main circulation pump into the reactor is called the primary circuit cold branch. For reducing heat losses, the piping is provided with removable thermal insulation.

Control room

Each of four reactor blocks is controlled from a separate control room - the block control room. The picture comes from the full-range simulator that is the true copy of the real block control room and simulates all its functions in every detail. The block control room simulator is used for training the personnel in the power plant since 1999. Since January 2001, the selected staff of the power plant has been trained on the simulator; this staff includes the primary and secondary circuit operators, the reactor block's managers, shift and safety engineers. . The basic training of operators takes more than two years. As required by law, operators must take training on the simulator every year, and pass state examinations repeatedly every two years.

Control room - blackout

In the situation when the power plant is not supplied, the function and visual appearance of the control room changes. Gleaming indicator lights and monitors are in sharp contrast to the whole control room's darkened area; the indicator lights and monitors are energised from a backup source. In this situation, it applies generally that the most important devices in the power plant are energised from accumulator batteries with the capacity at least two hours. The blackout status is declared in the reactor block. Immediately, the request goes to power dispatching centres in Prague, Brno and Ostrava for providing supply from the outer 400 kV or 110 kV mains from any source in the CR or abroad. For dispatching centres, resolving of the nuclear block blackout status is the highest priority even by law.

The provision of voltage from the nearby Dalešice hydro-engineering structure and water from the Mohelno equalising reservoir is thee well-tried and reliable variant. When the blackout occurs in the whole CR, a small water turbine is readied automatically in the Mohelno water flow power plant which will provide at request the electric voltage to some from four large (4 x 120 MW) turbines in the Dalešice pumped-storage power plant; this specific turbine will start up as needed and provide voltage to Dukovany through the Slavětice distribution point. This is called the blackstart. The mentioned capablity of the Dalešice power plant is subject to regular testing and certifying for all four turbines. In 1994 to 2004, the life test was performed with interconnection to Dukovany, including the start-up of important consumers. These tests were successful and confirmed that Dukovany would be capable, with the support from Dalešice, of safeguarding not only its reactors, but even restoring the whole energy system.

Controlled area relinquishing

In the Dukovany Nuclear Power Plant, the controlled area comprises the locations where radioactive substances (or other sources of ionising radiation) are handled, and where the regimen of protecting persons against the ionising radiation must be strictly adhered to. When leaving the controlled area, the person must surrender the dosimeter, pass through the dosimetric inspection and, again, pass the hygiene station.


In the regular shift, the Dukovany laundry launders 350 kg of laundry, i.e. the clothing of the controlled area staff. During shutdowns, the volume of laundry increases to 800 kg per shift due to repeated entries of a high number of people into the controlled area. The laundry is laundered in the chemically treated water and with a special detergent. Once dried, the laundry is subject to measuring the surface contamination.

In 2013, the Dukovany laundry laundered 105,010 kg of laundry; this volume is comparable to more than four loaded trucks weighing 25 tons. The Dukovany laundry employs 5 laundresses; each of them had to launder the laundry weighing more than 21 tons.

Laundry - ironing room

In the regular shift, the Dukovany laundry launders 350 kg of laundry, i.e. the clothing of the controlled area staff. During shutdowns, the volume of laundry increases to 800 kg per shift due to repeated entries of a high number of people into the controlled area. The laundry is laundered in the chemically treated water and with a special detergent. Once dried, the laundry is subject to measuring the surface contamination.

In 2013, the Dukovany laundry laundered 105,010 kg of laundry; this volume is comparable to more than four loaded trucks weighing 25 tons. The Dukovany laundry employs 5 laundresses; each of them had to launder the laundry weighing more than 21 tons.

Spent fuel storages

The spent fuel storages are represented by two halls. The first hall was put into operation in 1995 with the capacity of 60 CASTOR type containers. It was the first structure in the Czech Republic for which the EIA, i.e. the evaluation of the construction on the environment, was performed as early as in 1992. The hall was filled up after 15 years of operation; therefore, a second hall was constructed with the capacity of 133 CASTOR type containers.

The CASTOR container is a cylindrical thick-wall vessel made of ductile iron weighing 110 tons. It is 4.10 m high and 2.60 m in diameter. The container is equipped with ribbing on its surface to improve the residual heat removal. Inside the container, there is a boric grid into which 84 spent fuel cartridges fit (c. 10 tons of the spent fuel). The container is closed via a system of three lids. The container's inside and the space between first two lids is filled with pressurised helium, the inert gas that conducts heat well and, simultaneously, does not react with cartridges that passed the fission. . Storages are considered as the controlled area as the spent fuel is stored here. Containers are transferred to storages on a special railway carriage. The train comes on rails from the reactor hall corridor through the gate beside the ventilation smokestack. This is also the way used for taking the fresh fuel on trucks and empty CASTOR containers into the reactor hall. On the arrival to the storage, the portal crane moves the container from the carriage into the acceptance inspection room where the tightness test is performed. Then, the container is moved by the portal crane into the storage section where it is subject to various measurements, e.g. of pressure and temperature. The transfer of containers is done following very strict regulations. Each container has its technical passport for storing and transfer. Under fire, the container must withstand the direct flames for at least 30 minutes without any increase of temperature inside the container greater than 10°C.

The natural air circulation is used for cooling containers in storages. The cold air comes to storage halls through bottom jalousies along the buildings' periphery, and goes out through jalousie systems in their roofs. The fuel in containers produces heat due to radioactive wastes of unstable isotopes remaining after the fission. The intensity of the breakup and heat development decreases gradually along with the decrease of the fill radioactivity. The surface temperature of the first stored containers varies between 20 to 25°C depending on the outside temperature.

The spent fuel is not a waste to all intents and purposes. It still contains more than 96% of the unused energy. Therefore, it is considered the recyclable row material that can be relieved of breaking up fission products and a new fuel produced from it. Presently, the recycling of the spent fuel is more expensive than the production of the fuel from mined out uranium. Therefore, the interim storage is just temporary before the next development shows how to use it well further. The spent fuel also contains plutonium the International Nuclear Energy Agency (IAEA) monitors as the potential military material. Therefore, the spent fuel management is subject to very strict international inspections.

Diesel generators

For its operation, the Dukovany Nuclear Power Plant needs c. 9% of the electric energy of its own energy production. Each block returns for itself the electric energy from the mains through branch transformers of own consumption. In case the block fails to take this energy, it has available three backup Diesel generators with 2.8 MW of power output each. For safety, just one Diesel aggregate suffices. Two others are always in backup in case that another problem would occur.

As one of measures taken after the Fukushima nuclear power plant disaster, two more AAC Diesel aggregates were newly installed in the power plant. Thanks to their technical and operational parameters, they are a unique equipment capable of the completely independent operation. They will serve as the backup in case the power plant losses all the supply sources totalling 19 today. Each of the AAC Diesel aggregates is designed for one double-block; however, they can be interconnected if the need be. These generators with the power output of 3.2 MW each consume 787 l per hour of diesel in total at the 100% rated power output. The whole device consists of three containers and accessories.

Safety systems - Diesel aggregates - top view

In the Dukovany Nuclear Power Plant, all important control and safety systems are triple secured independently on each other. Then, the backup is 200%.

Radioactive waste processing building

The radioactive wastes are represented by unusable radioactive substances and items. In order to decrease its volume for storing, reduction of their volume is accentuated. The nuclear power plant generates both solid and liquid radioactive wastes. In Dukovany, the liquid radioactive waste is first taken from collection pools and forced through vaporisers (the so-called "concentrate" (concentrated salts) is produced) and then this concentrate is processed by the so-called "bitumenising" which is its fixing in asphalt resistant to water. This mix is filled in 200 l barrels and let to solidify. Then, the filled barrels are stored in the repository of low and medium radioactive waste in the power plant precinct.

Raw water pumping station

This is the raw water pumping station located at the lower reservoir of the Dalešice hydro-engineering structure, and the balancing water reservoir. Both facilities are important in terms of the Dukovany Nuclear Power Plant water supply. Pumps with discharge of 1,440 cu. m per hour and pressure of 1.32 MPa deliver the raw water from the Dalešice hydro-engineering structure lower reservoir (Mohelno) into the gravitational water reservoir. From here, water flows due to gravity through underground piping into the Dukovany Nuclear Power Plant precinct where it is further processed for its own need.


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