A nuclear power plant is an enterprise, which is a set of equipment and facilities for generating electrical energy. The specificity of this installation lies in the method of obtaining heat. The temperature required to generate electricity arises from the decay of atoms.
The role of fuel for nuclear power plants is most often performed by uranium with a mass number of 235 (235U). It is precisely because this radioactive element is capable of supporting a nuclear chain reaction that it is used in atomic power stations and is also used in nuclear weapons.
Countries with the most nuclear power plants
To date, 192 nuclear power plants operate in 31 countries of the world, using 451 nuclear power reactors with a total capacity of 394 GW. The vast majority of nuclear power plants are located in Europe, North America, Far East Asia and on the territory former USSR, while in Africa they are almost absent, and in Australia and Oceania they are not at all. Another 41 reactors have not produced electricity for 1.5 to 20 years, with 40 of them in Japan.
Over the past 10 years, 47 power units have been put into operation in the world, almost all of them are located either in Asia (26 in China) or in Eastern Europe. Two-thirds of those built on this moment reactors are in China, India and Russia. The PRC is implementing the most ambitious program for the construction of new nuclear power plants, and about a dozen other countries are building nuclear power plants or developing projects for their construction.
In addition to the United States, the list of the most advanced countries in the field of nuclear energy includes:
- France;
- Japan
- Russia;
- South Korea.
In 2007, Russia began construction of the world's first floating nuclear power plant to solve the problem of energy shortages in remote coastal regions of the country. Construction faced delays. According to various estimates, the first floating nuclear power plant will start operating in 2019-2019.
Several countries, including the USA, Japan, South Korea, Russia, Argentina, are developing mini-nuclear power plants with a capacity of about 10-20 MW for the purpose of heat and power supply to individual industries, residential complexes, and in the future - individual houses. It is assumed that small-sized reactors (see, for example, Hyperion NPP) can be created using safe technologies that greatly reduce the possibility of leakage of nuclear material. One CAREM25 small reactor is under construction in Argentina. The first experience of using mini-nuclear power plants was received by the USSR (Bilibino NPP).
The principle of operation of nuclear power plants
The principle of operation of a nuclear power plant is based on the operation of a nuclear (sometimes called nuclear) reactor - a special three-dimensional structure in which the reaction of splitting atoms occurs with the release of energy.
Exist different kinds nuclear reactors:
- PHWR (also called "pressurised heavy water reactor" - "heavy water nuclear reactor"), used mainly in Canada and in the cities of India. It is based on water, the formula of which is D2O. It performs the function of both a coolant and a neutron moderator. The efficiency is close to 29%;
- VVER (pressure-cooled power reactor). Currently, VVERs are operated only in the CIS, in particular, the VVER-100 model. The reactor has an efficiency of 33%;
- GCR, AGR (graphite water). The liquid contained in such a reactor acts as a coolant. In this design, the neutron moderator is graphite, hence the name. The efficiency is about 40%.
According to the principle of the device, reactors are also divided into:
- PWR (pressurised water reactor) - designed so that water under a certain pressure slows down reactions and supplies heat;
- BWR (designed in such a way that steam and water are in the main part of the device, without a water circuit);
- RBMK (channel reactor, having a particularly high power);
- BN (the system works due to the fast exchange of neutrons).
The device and structure of a nuclear power plant. How does a nuclear power plant work?
Typical nuclear power plant consists of blocks, inside each of which various technical devices are placed. The most significant of these units is a complex with a reactor hall, which ensures the operation of the entire nuclear power plant. It consists of the following devices:
- reactor;
- pool (it is in it that nuclear fuel is stored);
- vehicles reloading fuel;
- Main control room (control panel in blocks, with the help of which operators can observe the nuclear fission process).
This building is followed by a hall. It is equipped with steam generators and is the main turbine. Immediately behind them are capacitors, as well as electricity transmission lines that go beyond the boundaries of the territory.
Among other things, there is a block with pools for spent fuel and special blocks designed for cooling (these are called cooling towers). In addition, spray pools and natural reservoirs are used for cooling.
The principle of operation of nuclear power plants
At all nuclear power plants without exception, there are 3 stages of converting electrical energy:
- nuclear with a transition to thermal;
- thermal, turning into mechanical;
- mechanical, converting to electrical.
Uranium gives off neutrons, as a result of which heat is released in huge quantities. Hot water from the reactor is pumped through the steam generator, where it gives off part of the heat, and returns to the reactor again. Since this water is under high pressure, it remains in a liquid state (in modern VVER-type reactors, about 160 atmospheres at a temperature of ~330 °C). In the steam generator, this heat is transferred to the secondary circuit water, which is under much lower pressure (half the pressure of the primary circuit or less), and therefore boils. The resulting steam enters the steam turbine that rotates the electric generator, and then to the condenser, where the steam is cooled, it condenses and enters the steam generator again. The condenser is cooled with water from an external open source of water (eg cooling pond).
Both the first and second circuits are closed, which reduces the likelihood of radiation leakage. The dimensions of the primary circuit structures are minimized, which also reduces radiation risks. The steam turbine and condenser do not interact with the primary circuit water, which facilitates repairs and reduces the amount of radioactive waste during dismantling of the station.
NPP protective mechanisms
All nuclear power plants are required to be equipped with integrated safety systems, for example:
- localizing - limit the spread of harmful substances in the event of an accident that resulted in the release of radiation;
- providing - supply a certain amount of energy for the stable operation of systems;
- managers - serve to ensure that all protective systems function normally.
In addition, the reactor can be shut down in an emergency. In this case, automatic protection will interrupt the chain reactions if the temperature in the reactor continues to rise. This measure will subsequently require serious restoration work to return the reactor to service.
After a dangerous accident occurred at the Chernobyl nuclear power plant, the cause of which turned out to be the imperfection of the reactor design, they began to pay more attention to protective measures, and also carried out design work to ensure greater reliability of the reactors.
The catastrophe of the 21st century and its consequences
In March 2011, an earthquake hit the northeast of Japan, causing a tsunami that eventually damaged 4 of the 6 reactors at the Fukushima-1 nuclear power plant.
Less than two years after the tragedy, the official death toll in the disaster was over 1,500, while 20,000 people are still considered missing, and another 300,000 residents were forced to leave their homes.
There were also victims who were unable to leave the scene due to a huge dose of radiation. For them, an immediate evacuation was organized, which lasted 2 days.
Nevertheless, every year the methods of preventing accidents at nuclear power plants, as well as neutralizing emergencies, are being improved - science is steadily advancing. However, the future will clearly be a time of prosperity alternative ways generating electricity - in particular, it is logical to expect the appearance in the next 10 years of giant orbital solar panels, which is quite achievable in zero gravity, as well as other, including revolutionary technologies in the energy sector.
If you have any questions - leave them in the comments below the article. We or our visitors will be happy to answer them.
Nuclear power plant (NPP) - a complex of technical structures designed to generate electrical energy by using the energy released during a controlled nuclear reaction.
Uranium is used as a common fuel for nuclear power plants. The fission reaction is carried out in the main unit of a nuclear power plant - a nuclear reactor.
The reactor is mounted in a steel case designed for high pressure - up to 1.6 x 107 Pa, or 160 atmospheres.
The main parts of VVER-1000 are:
1. The core, where nuclear fuel is located, a chain reaction of nuclear fission proceeds and energy is released.
2. Neutron reflector surrounding the core.
3. Coolant.
4. Protection control system (CPS).
5. Radiation protection.
The heat in the reactor is released due to chain reaction division nuclear fuel under the action of thermal neutrons. In this case, nuclear fission products are formed, among which there are both solids and gases - xenon, krypton. Fission products have a very high radioactivity, so the fuel (uranium dioxide tablets) is placed in sealed zirconium tubes - TVELs (fuel elements). These tubes are combined several pieces side by side into a single fuel assembly. To control and protect a nuclear reactor, control rods are used that can be moved along the entire height of the core. The rods are made from substances that strongly absorb neutrons, such as boron or cadmium. With the deep introduction of the rods, the chain reaction becomes impossible, since the neutrons are strongly absorbed and removed from the reaction zone. The rods are moved remotely from the control panel. With a small movement of the rods, the chain process will either develop or decay. In this way, the power of the reactor is regulated.
The scheme of the station is two-circuit. The first, radioactive, circuit consists of one VVER 1000 reactor and four circulation cooling loops. The second circuit, non-radioactive, includes steam generator and water supply units and one turbine unit with a capacity of 1030 MW. The primary coolant is non-boiling water high purity under a pressure of 16 MPa with the addition of a solution of boric acid - a strong neutron absorber, which is used to control the power of the reactor.
1. The main circulation pumps pump water through the reactor core, where it is heated to a temperature of 320 degrees due to the heat released during a nuclear reaction.
2. The heated coolant gives off its heat to the water of the secondary circuit (working fluid), evaporating it in the steam generator.
3. The cooled coolant enters the reactor again.
4. The steam generator produces saturated steam at a pressure of 6.4 MPa, which is fed to the steam turbine.
5. The turbine drives the rotor of the electric generator.
6. The exhaust steam is condensed in the condenser and fed back to the steam generator by the condensate pump. To maintain a constant pressure in the circuit, a steam volume compensator is installed.
7. The heat of steam condensation is removed from the condenser by circulating water, which is supplied by a feed pump from the cooling pond.
8. Both the first and second circuits of the reactor are sealed. This ensures the safety of the reactor for personnel and the public.
If it is impossible to use a large amount of water for steam condensation, instead of using a reservoir, the water can be cooled in special cooling towers (cooling towers).
The safety and environmental friendliness of the reactor operation are ensured by strict compliance with the regulations (operational rules) and a large number of control equipment. All of it is designed for thoughtful and effective management reactor.
Emergency protection of a nuclear reactor - a set of devices designed to quickly stop a nuclear chain reaction in the reactor core.
Active emergency protection is automatically triggered when one of the parameters of a nuclear reactor reaches a value that can lead to an accident. Such parameters can be: temperature, pressure and flow rate of the coolant, level and rate of power increase.
The executive elements of emergency protection are, in most cases, rods with a substance that absorbs neutrons well (boron or cadmium). Sometimes a liquid scavenger is injected into the coolant loop to shut down the reactor.
In addition to active protection, many modern designs also include elements of passive protection. For example, modern versions of VVER reactors include the "Emergency Core Cooling System" (ECCS) - special tanks with boric acid located above the reactor. In the event of a maximum design basis accident (rupture of the primary cooling circuit of the reactor), the contents of these tanks are by gravity inside the reactor core and the nuclear chain reaction is quenched by a large amount of a boron-containing substance that absorbs neutrons well.
According to the "Nuclear Safety Rules for Reactor Installations of Nuclear Power Plants", at least one of the provided reactor shutdown systems must perform the function of emergency protection (EP). Emergency protection must have at least two independent groups of working bodies. At the signal of the AZ, the working bodies of the AZ must be actuated from any working or intermediate positions.
The AZ equipment must consist of at least two independent sets.
Each set of AZ equipment must be designed in such a way that, in the range of neutron flux density changes from 7% to 120% of the nominal value, protection is provided for:
1. According to the density of the neutron flux - at least three independent channels;
2. According to the rate of neutron flux density increase - by at least three independent channels.
Each set of AZ equipment must be designed in such a way that, in the entire range of process parameter changes established in the reactor plant (RP) design, emergency protection is provided by at least three independent channels for each process parameter for which protection is necessary.
The control commands of each set for AZ actuators must be transmitted over at least two channels. When one channel is taken out of operation in one of the AZ equipment sets without this set being taken out of operation, an alarm signal should be automatically generated for this channel.
Tripping of emergency protection should occur at least in the following cases:
1. Upon reaching the AZ setpoint in terms of neutron flux density.
2. Upon reaching the AZ setpoint in terms of the rate of increase in the neutron flux density.
3. In the event of a power failure in any set of AZ equipment and CPS power supply buses that have not been taken out of operation.
4. In case of failure of any two of the three channels of protection in terms of neutron flux density or in terms of neutron flux increase rate in any set of AZ equipment that has not been decommissioned.
5. When the AZ settings are reached by the technological parameters, according to which it is necessary to carry out protection.
6. When initiating the operation of the AZ from the key from the block control point (BCR) or the backup control point (RCP).
The material was prepared by the online editors www.rian.ru based on information from RIA Novosti and open sources
Nuclear power plant - complex necessary systems, devices, equipment and structures intended for the production of electrical energy. The station uses uranium-235 as fuel. The presence of a nuclear reactor distinguishes nuclear power plants from other power plants.
There are three mutual transformations of forms of energy at nuclear power plants
Nuclear power
goes into heat
Thermal energy
goes into mechanical
mechanical energy
converted to electrical
1. Nuclear energy turns into heat
The basis of the station is the reactor - a structurally allocated volume where nuclear fuel is loaded and where a controlled chain reaction takes place. Uranium-235 is fissile with slow (thermal) neutrons. As a result, it stands out great amount heat.
STEAM GENERATOR
2. Thermal energy is converted into mechanical
Heat is removed from the reactor core by a coolant - a liquid or gaseous substance passing through its volume. This thermal energy is used to produce water vapor in a steam generator.
POWER GENERATOR
3. Mechanical energy is converted into electrical energy
The mechanical energy of the steam is sent to the turbogenerator, where it is converted into electrical energy and then goes to the consumers through the wires.
What is a nuclear power plant made of?
A nuclear power plant is a complex of buildings that house technological equipment. The main building is the main building where the reactor hall is located. It houses the reactor itself, the nuclear fuel holding pool, the refueling machine (for fuel refueling), all this is monitored by operators from the block control room (BCR).
The main element of the reactor is the active zone (1) . It is located in a concrete shaft. Mandatory components of any reactor are a control and protection system that allows the selected mode of a controlled fission chain reaction to proceed, as well as an emergency protection system to quickly stop the reaction in the event of an emergency. All this is mounted in the main building.
There is also a second building where the turbine hall (2) is located: steam generators, the turbine itself. Next along the technological chain are capacitors and high-voltage power lines that go beyond the station site.
On the territory there is a building for reloading and storage of spent nuclear fuel in special pools. In addition, the stations are equipped with elements of a circulating cooling system - cooling towers (3) (a concrete tower tapering upwards), a cooling pond (natural or artificially created reservoir) and spray pools.
What are nuclear power plants?
Depending on the type of reactor, nuclear power plants can have 1, 2 or 3 coolant operation circuits. In Russia, bypass NPPs with VVER-type reactors (pressure-cooled power reactor) are most widely used.
NPP WITH 1-LOOP REACTORS
NPP WITH 1-LOOP REACTORS
The single-circuit scheme is used at nuclear power plants with RBMK-1000 type reactors. The reactor operates in a block with two condensing turbines and two generators. In this case, the boiling reactor itself is a steam generator, which makes it possible to use a single-loop scheme. The single-loop scheme is relatively simple, but the radioactivity in this case extends to all elements of the block, which complicates biological protection.
Currently, there are 4 nuclear power plants with single-loop reactors operating in Russia
NPP WITH 2-LOOP REACTORS
NPP WITH 2-LOOP REACTORS
The double-circuit scheme is used at nuclear power plants with water-cooled reactors of the VVER type. Pressurized water is supplied to the reactor core, which is heated. The energy of the coolant is used in the steam generator to form saturated steam. The second circuit is non-radioactive. The unit consists of one 1000 MW condensing turbine or two 500 MW turbines with associated generators.
Currently, Russia has 5 nuclear power plants with double-loop reactors
NPP WITH 3-LOOP REACTORS
NPP WITH 3-LOOP REACTORS
The three-loop scheme is used at nuclear power plants with fast neutron reactors with a sodium coolant of the BN type. To exclude the contact of radioactive sodium with water, a second circuit is constructed with non-radioactive sodium. Thus, the circuit turns out to be three-circuit.
How many of you have seen a nuclear power plant even from afar? Taking into account the fact that there are only ten operating nuclear power plants in Russia and they are protected, be healthy, I think the answer in most cases is negative. However, in LiveJournal, people, as you know, are experienced. Okay, but how many then saw the nuclear power plant from the inside? Well, for example, did you feel the vessel of a nuclear reactor with your own hand? Nobody. I guessed?
Well, today all subscribers of this photoblog have the opportunity to see all these high tech as close as possible. I understand that live it is much more interesting at times, but let's start small. In the future, perhaps, I will be able to take a few people with me, but for now we are studying the materiel!
02
. So, we are forty-five kilometers away from the construction site of the 4th stage of the Novovoronezh NPP. Not far from the operating nuclear power plant (the first power unit was launched back in the sixties of the last century), two modern power units with a total capacity of 2400 MW are being built. The construction is carried out according to the new AES-2006 project, which provides for the use of VVER-1200 reactors. But about the reactors themselves a little later. 
03
. It is the fact that the construction is not yet completed that gives us a rare chance to see everything with our own eyes. Even the reactor hall, which in the future will be hermetically sealed and opened for maintenance only once a year. 
04
. As you can see in the previous photo, the dome of the outer containment of the seventh power unit is still at the stage of concreting, but the reactor building of power unit No. 6 already looks more interesting (see photo below). In total, the concreting of this dome required more than 2,000 cubic meters of concrete. The diameter of the dome at the base is 44 m, the thickness is 1.2 m. Pay attention to the green pipes and the voluminous metal cylinder (weight - 180 tons, diameter - about 25 m, height - 13 m) - these are elements of the passive heat removal system (PHS). ). They are being installed at the Russian NPP for the first time. In the event of a complete blackout of all NPP systems (as happened at Fukushima), the PHRS is capable of providing long-term heat removal from the reactor core. 
05
. Undoubtedly, the most large-scale element of nuclear power plants are tower cooling towers. In addition, it is one of the most efficient devices for cooling water in circulating water supply systems. The high tower creates the very draft of air that is necessary for the effective cooling of the circulating water. Thanks to the high tower, one part of the vapor is returned to the cycle, while the other is carried away by the wind. 
06
. The height of the shell of the tower cooling tower of power unit No. 6 is 171 meters. It's about 60 floors. Now this building is the highest among similar ones ever built in Russia. Its predecessors did not exceed 150 m in height (at the Kalinin NPP). It took more than 10 thousand cubic meters of concrete to build the structure. 
07
. At the base of the cooling tower (diameter is 134 m) is the so-called pool bowl. Its upper part is "paved" with irrigation blocks. The fill is the main structural element of this type of cooling tower, designed to break up the flow of water flowing through it and provide it with a long time and maximum contact area with the cooling air. In essence, these are lattice modules made of modern polymeric materials. 
08
. Naturally, I wanted to take an epic shot of the top, but the already mounted sprinkler prevented me from doing this. Therefore, we move to the cooling tower of power unit No. 7. Alas, it was frosty at night and we broke off with the elevator ride to the very top. He froze. 
09
. Okay, maybe someday I'll have a chance to ride on such a top, but for now, a frame of an irrigation system being mounted. 
10
. I thought about it ... Or maybe we were simply not allowed to go upstairs for security reasons? 
11
. The entire territory of the construction site is full of warning, prohibiting and simply propaganda posters and signs. 
12
. OK. We teleport to the building of the central control panel (CSC).
Well, of course, nowadays everything is controlled by computers. 
13
. The huge room, flooded with light, is literally crammed with orderly rows of cabinets with automatic relay protection systems. 
14
. Relay protection continuously monitors the state of all elements of the electric power system and reacts to the occurrence of damage and / or abnormal modes. In the event of damage, the protection system must identify a specific damaged area and turn it off by acting on special power switches designed to open fault currents (short circuit or earth fault). 
15
. Fire extinguishers are placed along each wall. Automatic, of course. 
16
. Next, we move to the building of a complete switchgear for 220 kV (KRUE-220). One of the most photogenic places in the entire nuclear power plant, in my opinion. There is also KRUE-500, but it was not shown to us. KRUE-220 is part of the general station electrical equipment and is designed to receive power from external power lines and distribute it at the site of the station under construction. That is, while the power units are being built, with the help of KRUE-220, the facilities under construction are directly supplied with electricity. 
17
. In the AES-2006 project, according to which the sixth and seventh power units are being built, for the first time in the scheme of power distribution at distribution substations, packaged switchgears 220/500 kV of a closed type with SF6 insulation were used. Compared to open switchgears, which have been used in the nuclear power industry so far, the area of closed switchgear is several times smaller. To understand the scale of the building, I recommend returning to the title photo. 
18
. Naturally, after the new power units are put into operation, the KRUE-220 equipment will be used to transfer electricity generated at the Novovoronezh NPP to the Unified Energy System. Pay attention to the boxes near the power lines. Most electrical equipment used in construction is manufactured by Siemens. 
19
. But not only. Here, for example, is a Hyundai autotransformer.
The weight of this unit is 350 tons, and it is designed to convert electricity from 500 kV to 220 kV. 
20
. There are (which is nice) our solutions. Here, for example, is a step-up transformer manufactured by Elektrozavod JSC. Established in 1928, the first domestic transformer plant played a colossal role in the industrialization of the country and in the development of domestic energy. Equipment with the brand name "Electrozavod" operates in more than 60 countries around the world. 
21
. Just in case, I will explain a little about transformers. In general, the power distribution scheme (after completion of construction and commissioning, of course) provides for the production of electricity with a voltage of two classes - 220 kV and 500 kV. At the same time, the turbine (about it later) generates only 24 kV, which are fed through the conductor to the block transformer, where they rise to 500 kV. After that, a part of the power capacity is transferred through the KRUE-500 to the Unified Energy System. The other part goes to autotransformers (those same Hyundais), where it drops from 500 kV to 220 kV and also enters the power system through KRUE-220 (see above). So, as the mentioned block transformer, three single-phase step-up "electric factory" transformers are used (the power of each is 533 MW, the weight is 340 tons). 
22
. If it is clear, let's move on to the steam turbine plant of power unit No. 6. Forgive me, my story seems to go from the end to the beginning (if we start from the process of generating electricity), but approximately in this sequence we walked around the construction site. So I beg your pardon. 
23
. So, the turbine and generator are hidden under the casing. Therefore, I explain. Actually, a turbine is a unit in which the thermal energy of steam (with a temperature of about 300 degrees and a pressure of 6.8 MPa) is converted into mechanical energy rotation of the rotor, and already on the generator - to the desired electrical energy. The weight of the machine in the assembled state is more than 2600 tons, the length is 52 meters, it consists of more than 500 components. To transport this equipment to construction site about 200 trucks were involved. This K-1200–7-3000 turbine was manufactured at the Leningrad Metal Plant and is the first high-speed (3000 rpm) turbine with a capacity of 1200 MW in Russia. This innovative development was created specifically for nuclear power units of a new generation, which are being built according to the AES-2006 project. On the picture general form turbine shop. Or a turbine hall, if you like. The old-school nuclear scientists call the turbine a machine. 
24
. One floor below are the turbine condensers. The capacitor group belongs to the main technological equipment engine room and, as everyone has already guessed, is designed to turn the steam exhausted in the turbine into liquid. The resulting condensate after the necessary regeneration is returned to the steam generator. The weight of the equipment of the condensing unit, which includes 4 condensers and a piping system, is more than 2000 tons. Inside the capacitors there are about 80,000 titanium tubes that form a heat transfer surface. with total area 100 thousand square meters. 
25
. Got it? Here is the building of the turbine hall almost in section and we move on. At the very top of the overhead crane. 
26
. We are moving to the block control panel of power unit No. 6.
The purpose, I think, is clear without explanation. Figuratively speaking, this is the brain of a nuclear power plant. 
27
. BPU elements. 
28
. And finally, we are going to see the premises of the reactor compartment! Actually, this is the place where the nuclear reactor, the primary circuit and their auxiliary equipment are located. Naturally, in the foreseeable future it will become airtight and inaccessible. 
29
. And in the most natural way, when you get inside, the first thing you do is lift your head and marvel at the size of the containment dome. Well, a polar crane at the same time. A circular overhead crane (polar crane) with a lifting capacity of 360 tons is designed for the installation of large-sized and heavy containment equipment (reactor vessel, steam generators, pressure compensator, etc.). After the nuclear power plant is put into operation, the crane will be used for repair work and transportation of nuclear fuel. 
30
. Further, of course, I rush to the reactor and watch its upper part in fascination, not yet suspecting that the situation is similar with icebergs. So that's what you are, reindeer. Figuratively speaking, this is the heart of a nuclear power plant. 
31
. Reactor vessel flange. Later, an upper unit with CPS drives (reactor control and protection system) will be installed on it, which provides sealing of the main connector. 
32
. Nearby we observe the pool of exposure. Its inner surface is a welded structure made of stainless steel sheet. It is designed for temporary storage of spent nuclear fuel unloaded from the reactor. After the residual heat release is reduced, the used fuel is transported from the spent fuel pool to the nuclear industry enterprise engaged in fuel reprocessing and regeneration (storage, disposal or reprocessing). 
33
. And this is along the wall of the hydraulic tanks of the passive bay system of the core. They belong to passive safety systems, that is, they operate without the involvement of personnel and the use of external sources of energy supply. Simplifying, these are giant barrels filled with an aqueous solution of boric acid. In the event of an emergency, when the pressure in the primary circuit drops below a certain level, liquid is supplied to the reactor and the core is cooled. Thus, the nuclear reaction is quenched by a large amount of boron-containing water that absorbs neutrons. It should be noted that in the AES-2006 project, according to which the fourth stage of the Novovoronezh NPP is being built, for the first time an additional, second, stage of protection is provided - hydraulic reservoirs of the passive bay of the core (8 out of 12 reservoirs), each with a volume of 120 cubic meters. 
34
. During future scheduled preventive maintenance and replacement of nuclear fuel, it will be possible to get inside the reactor compartment through the transport lock. It is a 14-meter cylindrical chamber with a diameter of more than 9 meters, hermetically locked on both sides with gate leaves that open alternately. The total weight of the lock is about 230 tons. 
35
. From the outside of the lock, a panoramic view of the entire construction site as a whole and power unit No. 7 in particular opens up. 
36
. Well, after taking a breath of fresh air, we go down below to see, in fact, the cylindrical reactor vessel. But so far we have come across only technological pipelines. The big green pipe is one of the loops, so we're pretty close now. 
37
. And here he is. Pressurized pressurized pressurized water reactor VVER-1200. I will not delve into the jungle of nuclear fission and nuclear chain reaction (go ahead and already read diagonally), I will only add that inside the reactor there are many fuel elements (the so-called fuel rods) in the form of a set of sealed tubes made of special alloys with a diameter of 9.1 -13.5 mm and several meters long, filled with nuclear fuel pellets, as well as control rods that can be remotely moved from the control panel along the entire height of the core. These rods are made from substances that absorb neutrons, such as boron or cadmium. With the deep introduction of the rods, the chain reaction becomes impossible, since the neutrons are strongly absorbed and removed from the reaction zone. In this way, the power of the reactor is regulated. Now it is clear why there are so many holes in the upper part of the reactor? 
38
. Yes, I almost forgot about the main circulation pump (MCP). It also belongs to the main technological equipment of the reactor building and is designed to create coolant circulation in the primary circuit. Within an hour, the unit pumps over 25 thousand cubic meters of water. The MCP also provides core cooling in all operating modes of the reactor plant. The installation includes four MCPs. 
39
. Well, to consolidate the material covered, we look at the simplest scheme of the operation of a nuclear power plant. It's simple, isn't it? In especially neglected cases, re-read the post again, hehe))
40
. It's kind of like this in general. But for those who are close to the topic, I will throw in a few more cards with people. Agree, there are not so many of them in the report, and meanwhile, since 2006, many thousands of specialists of various profiles have worked here. 
41
. Someone below... 
42
. And someone at the top... Although you don't see them, they are there. 
43
. And this is one of the most honored builders of the Novovoronezh NPP - a DEMAG crawler crane. It was he who lifted and installed these multi-ton elements of the reactor and engine rooms (load capacity - 1250 tons). Uncle-installer and a truck to understand the scale, and in full height (115 meters) look at the handsome man in photos 03 and 04. 
And as a conclusion. Since March of this year, for reasons unknown to me, the operating Novovoronezh NPP and the Novovoronezh NPP-2 under construction have been merged. What we visited and what we used to call NVNPP-2 is now called the fourth stage of NVNPP, and the power units under construction have turned from the first and second into the sixth and seventh, respectively. Infa 110%. Those who wish can immediately go to rewrite articles on Wikipedia, and I thank the staff of the department for relations with NVNPP power units under construction and especially Tatyana, without whom this excursion would most likely not have taken place. Also, my thanks for the educational program on the construction of nuclear power plants to the shift supervisor Roman Vladimirovich Gridnev, as well as Vladimir
NUCLEAR POWER PLANT(NPP), a power plant that uses the heat released in a nuclear reactor as a result of a controlled chain reaction of nuclear fission of heavy elements to generate electricity (in the main. $\ce(^(233)U, ^(235)U, ^(239)Pu)$). The heat generated in core nuclear reactor, is transmitted (directly or through an intermediate coolant) working fluid (predominantly water vapor), which drives steam turbines with turbogenerators.
A nuclear power plant is, in principle, an analogue of a conventional thermal power plant(TPP), in which a nuclear reactor is used instead of a steam boiler furnace. However, despite the similarity of the fundamental thermodynamic schemes of nuclear and thermal power plants, there are also significant differences between them. The main ones are the environmental and economic advantages of nuclear power plants over thermal power plants: nuclear power plants do not need oxygen to burn fuel; they do not pollute environment sulfurous and other gases; nuclear fuel has a significantly higher calorific value (fission of 1 g of U or Pu isotopes releases 22,500 kWh, which is equivalent to the energy contained in 3,000 kg hard coal), which dramatically reduces its volume and the cost of transportation and handling; world energy resources of nuclear fuel significantly exceed the natural reserves of hydrocarbon fuel. In addition, the use of nuclear reactors (of any type) as an energy source requires a change in the thermal schemes adopted at conventional thermal power plants and the introduction of new elements into the structure of nuclear power plants, for example. biological protection (see Radiation safety), systems for reloading spent fuel, a fuel pool, etc. The transfer of thermal energy from a nuclear reactor to steam turbines is carried out by means of a coolant circulating through sealed pipelines, in combination with circulation pumps that form the so-called. reactor circuit or loop. Normal and heavy water, water vapor, liquid metals, organic liquids, and some gases (for example, helium, carbon dioxide) are used as heat carriers. The circuits through which the coolant circulates are always closed to avoid leakage of radioactivity, their number is determined mainly by the type of nuclear reactor, as well as the properties of the working fluid and coolant.
At nuclear power plants with a single-loop scheme (Fig., A) the coolant is also a working fluid, the entire circuit is radioactive and therefore surrounded by biological protection. When using an inert gas as a coolant, such as helium, which is not activated in the neutron field of the core, biological protection is necessary only around the nuclear reactor, since the coolant is not radioactive. The coolant - the working fluid, heating up in the reactor core, then enters the turbine, where its thermal energy is converted into mechanical energy and then in the electric generator - into electrical energy. The most common are single-circuit nuclear power plants with nuclear reactors, in which the coolant and neutron moderator serves as water. The working fluid is formed directly in the core when the coolant is heated to boiling. Such reactors are called boiling water reactors, in the world nuclear power industry they are referred to as BWR (Boiling Water Reactor). In Russia, boiling water reactors with a water coolant and a graphite moderator - RBMK (high power channel reactor) have become widespread. The use of high-temperature gas-cooled reactors (with helium coolant) - HTGR (HTGR) at NPPs is considered promising. The efficiency of single-loop NPPs operating in a closed gas turbine cycle can exceed 45–50%.
With a two-circuit scheme (Fig., b) the primary coolant heated in the core is transferred to the steam generator ( heat exchanger) thermal energy to the working fluid in the second circuit, after which it is returned to the core by the circulation pump. The primary coolant can be water, liquid metal or gas, and the working fluid is water, which turns into water vapor in the steam generator. The primary circuit is radioactive and is surrounded by biological shielding (except when an inert gas is used as a coolant). The second circuit is usually radiation safe, since the working fluid and the coolant of the primary circuit do not come into contact. The most widespread are double-loop nuclear power plants with reactors in which water is the primary coolant and moderator, and steam is the working fluid. This type of reactor is referred to as VVER - pressurized water power. reactor (PWR - Power Water Reactor). The efficiency of nuclear power plants with VVER reaches 40%. In terms of thermodynamic efficiency, such NPPs are inferior to single-loop NPPs with HTGR if the temperature of the gas coolant at the exit from the core exceeds 700 °C.
Three-circuit thermal schemes(rice., V) are used only in those cases when it is necessary to completely exclude the contact of the coolant of the first (radioactive) circuit with the working fluid; for example, when the core is cooled with liquid sodium, its contact with the working fluid (steam) can lead to a major accident. Liquid sodium as a coolant is used only in nuclear reactor x on fast neutrons (FBR - Fast Breeder Reactor). A feature of nuclear power plants with a fast neutron reactor is that, simultaneously with the generation of electrical and thermal energy, they reproduce fissile isotopes suitable for use in thermal nuclear reactors (see Fig. Breeder Reactor).
Nuclear power plant turbines usually operate on saturated or slightly superheated steam. When using turbines operating on superheated steam, saturated steam is passed through the reactor core (through special channels) or through a special heat exchanger - a hydrocarbon-fueled superheater to increase the temperature and pressure. The thermodynamic efficiency of the NPP cycle is the higher, the higher the parameters of the coolant, the working fluid, which are determined by the technological capabilities and properties of structural materials used in the NPP cooling circuits.
At nuclear power plants, much attention is paid to the purification of the coolant, since the natural impurities present in it, as well as corrosion products that accumulate during the operation of equipment and pipelines, are sources of radioactivity. The degree of purity of the coolant largely determines the level of the radiation situation in the premises of the NPP.
Nuclear power plants are almost always built near energy consumers, because the cost of transporting nuclear fuel to nuclear power plants, in contrast to hydrocarbon fuel for thermal power plants, has little effect on the cost of generated energy (usually, nuclear fuel in power reactors is replaced with a new one once every several years). years), and the transmission of both electrical and thermal energy over long distances significantly increases their cost. Nuclear power plants are built on the leeward side of the nearest settlement, a sanitary protection zone and an observation zone are created around it, where the population is unacceptable. Control and measuring equipment for continuous monitoring of the environment is placed in the observation zone.
NPP - the basis nuclear power. Their main purpose is the production of electricity (nuclear power plants of the condensing type) or the combined production of electricity and heat (nuclear combined heat and power plants - ATES). At the NPP, part of the steam exhausted in the turbines is diverted to the so-called. network heat exchangers for heating water circulating in closed heat supply networks. In some cases, the thermal energy of nuclear reactors can only be used for heating needs (nuclear heat supply stations - AST). In this case, the heated water from the heat exchangers of the first and second circuits enters the network heat exchanger, where it gives off heat to the network water and then returns to the circuit.
One of the advantages of nuclear power plants compared to conventional thermal power plants is their high environmental friendliness, which is maintained with qualification. operation of nuclear reactors. The existing NPP radiation safety barriers (fuel rod cladding, nuclear reactor vessel, etc.) prevent contamination of the coolant with radioactive fission products. A protective shell (containment) is being erected over the reactor hall of the NPP to prevent radioactive materials from entering the environment during the most severe accident - depressurization of the primary circuit, melting of the core. NPP personnel training provides for training on special simulators (NPP simulators) for practicing actions both in normal and emergency situations. The NPP has a number of services that ensure the normal functioning of the station, the safety of its personnel (for example, dosimetric control, ensuring sanitary and hygienic requirements, etc.). On the territory of the nuclear power plant, temporary storage facilities are created for fresh and spent nuclear fuel, for liquid and solid radioactive waste that appears during its operation. All this leads to the fact that the cost of an installed kilowatt of power at nuclear power plants is more than 30% higher than the cost of a kilowatt at thermal power plants. However, the cost of energy supplied to the consumer, generated at nuclear power plants, is lower than at thermal power plants, due to the very small share of the fuel component in this cost. Due to high efficiency and features of power control, NPPs are usually used in basic modes, while the installed capacity utilization factor of NPPs can exceed 80%. As the share of nuclear power plants in the total energy balance of the region increases, they can also operate in a maneuver mode (to cover load irregularities in the local energy system). The ability of nuclear power plants to operate for a long time without changing fuel allows them to be used in remote regions. NPPs have been developed whose equipment layout is based on the principles implemented in shipboard nuclear power plants. installations (see Nuclear ship). Such nuclear power plants can be placed, for example, on a barge. Promising nuclear power plants with HTGR, generating thermal energy for the implementation of technological processes in the metallurgical, chemical and oil industries, in the gasification of coal and shale, in the production of synthetic hydrocarbon fuels. The NPP operation life is 25–30 years. The decommissioning of a nuclear power plant, the dismantling of the reactor and the reclamation of its site to the state of a “green lawn” is a complex and expensive organizational and technical measure carried out according to plans developed in each specific case.
The world's first operating nuclear power plant with a capacity of 5000 kW was launched in Russia in 1954 in the city of Obninsk. In 1956, the nuclear power plant at Calder Hall in the UK (46 MW) was put into operation, in 1957 the nuclear power plant at Shippingport in the USA (60 MW) was put into operation. In 1974, the world's first thermal power plant, the Bilibinskaya (Chukotka Autonomous Okrug), was launched. Mass construction of large economical nuclear power plants began in the 2nd half. 1960s However, after the accident (1986) at the Chernobyl nuclear power plant, the attractiveness of nuclear energy has noticeably decreased, and in a number of countries that have sufficient own traditional fuel and energy resources or access to them, the construction of new nuclear power plants has actually stopped (Russia, USA, Great Britain, Germany). At the beginning of the 21st century, on March 11, 2011, in the Pacific Ocean off the east coast of Japan, as a result of a strong earthquake with a magnitude of 9.0 to 9.1 and the subsequent tsunami(wave height reached 40.5 m) at the Fukushima1 nuclear power plant (Okuma Township, Fukushima Prefecture) the largesttechnological disaster– radiation accident of the maximum level 7 according to the International Nuclear Event Scale. The tsunami hit disabled external power supplies and backup diesel generators, which caused the inoperability of all normal and emergency cooling systems and led to the melting of the reactor core at power units 1, 2 and 3 in the first days of the accident. In December 2013, the nuclear power plant was officially closed. As of the first half of 2016, a high level of radiation makes it impossible to work not only for people in reactor buildings, but also for robots, which fail due to a high level of radiation. It is planned that the removal of soil layers to special storage facilities and its destruction will take 30 years.
31 countries of the world use nuclear power plants. Valid for 2015 is approx. 440 nuclear power reactors (power units) with a total capacity of more than 381,000 MW (381 GW). OK. 70 nuclear reactors are under construction. The world leader in terms of share in total electricity generation is France (second place in terms of installed capacity), in which nuclear power is 76.9%.
The largest nuclear power plant in the world in 2015 (in terms of installed capacity) is Kashiwazaki-Kariwa (Kashiwazaki, Niigata Prefecture, Japan). There are 5 boiling water reactors (BWRs) and 2 advanced boiling water reactors (ABWRs) in operation, with a combined capacity of 8212 MW (8.212 GW).
The largest nuclear power plant in Europe is the Zaporozhye NPP (Energodar, Zaporozhye region, Ukraine). Since 1996, 6 power units with VVER-1000 reactors have been operating with a total capacity of 6,000 MW (6 GW).
| Table 1. The largest consumers of nuclear power in the world | |||
| State | Number of power units | Total power (MW) | Total generated electricity (billion kWh/year) |
| USA | 104 | 101 456 | 863,63 |
| France | 58 | 63 130 | 439,74 |
| Japan | 48 | 42 388 | 263,83 |
| Russia | 34 | 24 643 | 177,39 |
| South Korea | 23 | 20 717 | 149,2 |
| China | 23 | 19 907 | 123,81 |
| Canada | 19 | 13 500 | 98,59 |
| Ukraine | 15 | 13 107 | 83,13 |
| Germany | 9 | 12 074 | 91,78 |
| Great Britain | 16 | 9373 | 57,92 |
The United States and Japan are developing mini-nuclear power plants with a capacity of about 10–20 MW for heat and power supply to individual industries, residential complexes, and, in the future, individual houses. Small-sized reactors are created using safe technologies that greatly reduce the possibility of leakage of nuclear material.
As of 2015, 10 NPPs operate in Russia, which operate 34 power units with a total capacity of 24,643 MW (24.643 GW), of which 18 power units are with VVER-type reactors (including 11 VVER-1000 power units and 6 VVER-440 power units of various modifications); 15 power units with channel reactors (11 power units with RBMK-1000 type reactors and 4 power units with EGP-6 type reactors - Energy Heterogeneous Loop Reactor with 6 coolant circulation loops, electric power 12 MW); 1 power unit with sodium-cooled fast neutron reactor BN-600 (1 power unit BN-800 is in the process of being put into commercial operation). According to the Federal Target Program "Development of the Russian Nuclear Power Industry Complex", by 2025 the share of electricity generated at nuclear power plants in the Russian Federation should increase from 17 to 25% and amount to approx. 30.5 GW. It is planned to build 26 new power units, 6 new nuclear power plants, two of which are floating (Table 2).
| Table 2. NPPs operating on the territory of the Russian Federation | ||||
| NPP name | Number of power units | Years of commissioning of power units | Total installed capacity (MW) | Reactor type |
| Balakovo NPP (near Balakovo) | 4 | 1985, 1987, 1988, 1993 | 4000 | VVER-1000 |
| Kalinin NPP [125 km from Tver on the banks of the Udomlya River (Tver region)] | 4 | 1984, 1986, 2004, 2011 | 4000 | VVER-1000 |
| Kursk NPP (near the city of Kurchatov on the left bank of the Seim River) | 4 | 1976, 1979, 1983, 1985 | 4000 | RBMK-1000 |
| Leningrad NPP (near Sosnovy Bor) | 4 under construction - 4 | 1973, 1975, 1979, 1981 | 4000 | RBMK-1000 (the first plant in the country with reactors of this type) |
| Rostov NPP (located on the banks of the Tsimlyansk reservoir, 13.5 km from the city of Volgodonsk) | 3 | 2001, 2010, 2015 | 3100 | VVER-1000 |
| Smolensk NPP (3 km from the satellite town of Desnogorsk) | 3 | 1982, 1985, 1990 | 3000 | RBMK-1000 |
| Novovoronezh NPP (near Novovoronezh) | 5; (2 - withdrawn), under construction - 2. | 1964 and 1969 (withdrawn), 1971, 1972, 1980 | 1800 | VVER-440; VVER-1000 |
| Kola NPP (200 km south of Murmansk on the shores of Lake Imandra) | 4 | 1973, 1974, 1981, 1984 | 1760 | VVER-440 |
| Beloyarsk NPP (near Zarechny) | 2 | 1980, 2015 | 600 800 | BN-600 BN-800 |
| Bilibino NPP | 4 | 1974 (2), 1975, 1976 | 48 | EGP-6 |
Projected NPPs in the Russian Federation
Since 2008, according to the new project NPP-2006 (the project of the Russian nuclear power plant of the new generation "3+" with improved technical and economic indicators), Novovoronezh NPP-2 (near Novovoronezh NPP) is being built, which provides for the use of VVER-1200 reactors. The construction of 2 power units with a total capacity of 2400 MW is underway, in the future it is planned to build 2 more.
The Baltic NPP provides for the use of a VVER-1200 reactor plant with a capacity of 1200 MW; power units - 2. The total installed capacity is 2300 MW. Commissioning of the first unit is planned for 2020. federal agency Atomic Energy of Russia is conducting a project to create low-power floating nuclear power plants. The Akademik Lomonosov nuclear power plant under construction will be the world's first floating nuclear power plant. The floating station can be used to generate electricity and heat, as well as to desalinate sea water. It can produce from 40 to 240 thousand m 2 of fresh water per day. The installed electric power of each reactor is 35 MW. Commissioning of the station is planned for 2018.
International projects of Russia on nuclear energy
23.9.2013 Russia handed over to Iran the operation of the Bushehr NPP (Bushir) , near the town of Bushehr (Bushir stop); number of power units - 3 (1 built, 2 - under construction); reactor type - VVER-1000. NPP "Kudankulam", near the city of Kudankulam (Tamil Nadu, India); number of power units - 4 (1 - in operation, 3 - under construction); reactor type - VVER-1000. NPP "Akkuyu", near the city of Mersin (il Mersin, Turkey); number of power units - 4 (under construction); reactor type - VVER-1200; Belarusian NPP (Ostrovets, Grodno region, Belarus); number of power units - 2 (under construction); reactor type - VVER-1200. NPP Hanhikivi 1 (Cape Hanhikivi, Pohjois-Pohjanmaa region, Finland); number of power units - 1 (under construction); reactor type - VVER-1200.
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