A nuclear power plant is an enterprise that is a set of equipment and structures for generating electrical energy. The specificity of this installation lies in the method of generating 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 nuclear power plants. power stations, and is also used in nuclear weapons.
Countries with the largest number of nuclear power plants
Today, there are 192 nuclear power plants operating in 31 countries around the world, using 451 nuclear power reactors with a total capacity of 394 GW. The vast majority of nuclear power plants are located in European countries, North America, Far East Asia and in the territory former USSR, while in Africa there are almost none, and in Australia and Oceania there are none at all. Another 41 reactors have not produced electricity for 1.5 to 20 years, with 40 of them located in Japan.
Over the past 10 years, 47 power units have been put into operation around the world, almost all of them are located either in Asia (26 in China) or in Eastern Europe. Two thirds of those being built on this moment reactors are in China, India and Russia. The PRC is implementing the largest program for the construction of new nuclear power plants; about a dozen other countries around the world 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, which would solve the problem of energy shortages in remote coastal areas of the country. Construction has 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 electricity 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 nuclear leakage. Construction of one small reactor CAREM25 is underway in Argentina. The first experience in using mini-nuclear power plants was gained by the USSR (Bilibino NPP).
Operating principle of nuclear power plants
The operating principle of a nuclear power plant is based on the action of a nuclear (sometimes called atomic) reactor - a special volumetric structure in which the reaction of atoms splitting with the release of energy occurs.
Exist different kinds nuclear reactors:
- PHWR (also called "pressurized heavy water reactor" - "heavy water nuclear reactor"), used mainly in Canada and in Indian cities. It is based on water, the formula of which is D2O. It functions as both a coolant and a neutron moderator. The efficiency is close to 29%;
- VVER (water-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%.
Based on the design principle, reactors are also divided into:
- PWR (pressurized 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 having a water circuit);
- RBMK (channel reactor with particularly high power);
- BN (the system works due to the rapid exchange of neutrons).
Design 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 the complex with the reactor hall, which ensures the operation of the entire nuclear power plant. It consists of the following devices:
- reactor;
- pool (this is where nuclear fuel is stored);
- fuel transfer machines;
- Control room (control panel in blocks, with the help of which operators can monitor the core fission process).
This building is followed by a hall. It contains steam generators and the main turbine. Immediately behind them are capacitors, as well as electricity transmission lines that extend beyond the boundaries of the territory.
Among other things, there is a block with pools for spent fuel and special blocks designed for cooling (they are called cooling towers). In addition, spray pools and natural ponds are used for cooling.
Operating principle of nuclear power plants
At all nuclear power plants without exception, there are 3 stages of electrical energy conversion:
- nuclear with transition to thermal;
- thermal, turning into mechanical;
- mechanical, converted into electrical.
Uranium gives off neutrons, resulting in the release of heat in huge quantities. Hot water from the reactor is pumped through a steam generator, where it gives off some of the heat, and is returned to the reactor. Since this water is under high pressure, it remains in a liquid state (in modern VVER-type reactors there are 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 a steam turbine that rotates an electric generator, and then into a condenser, where the steam is cooled, it condenses and again enters the steam generator. The condenser is cooled with water from an external open water source (for example, a 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 when dismantling the station.
Nuclear power plant protective mechanisms
All nuclear power plants are required to be equipped with comprehensive safety systems, for example:
- localizing – limiting the spread of harmful substances in the event of an accident resulting in the release of radiation;
- providing – supply a certain amount of energy for 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 chain reactions if the temperature in the reactor continues to rise. This measure will subsequently require serious restoration work to return the reactor to operation.
After a dangerous accident occurred at the Chernobyl nuclear power plant, the cause of which was an imperfect reactor design, they began to pay more attention to protective measures, and also carried out design work to ensure greater reliability of the reactors.
Catastrophe of the 21st century and its consequences
In March 2011, an earthquake struck northeastern Japan, causing a tsunami that ultimately damaged 4 of the 6 reactors at the Fukushima Daiichi Nuclear Power Plant.
Less than two years after the tragedy, the official death toll in the disaster exceeded 1,500 people, while 20,000 people are still 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 the huge dose of radiation. An immediate evacuation was organized for them, which lasted 2 days.
However, every year, methods for preventing accidents at nuclear power plants, as well as neutralizing emergencies, are being improved - science is steadily moving forward. However, the future will clearly be a time of prosperity alternative ways obtaining electricity - in particular, it is logical to expect the appearance in the next 10 years of gigantic orbital solar panels, which is quite achievable in conditions of weightlessness, 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) is 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 casing designed for high pressure - up to 1.6 x 107 Pa, or 160 atmospheres.
The main parts of VVER-1000 are:
1. The active zone, where nuclear fuel is located, a chain reaction of nuclear fission occurs and energy is released.
2. Neutron reflector surrounding the core.
3. Coolant.
4. Protection control system (CPS).
5. Radiation protection.
Heat in the reactor is released due to chain reaction divisions nuclear fuel under the influence of thermal neutrons. In this case, nuclear fission products are formed, among which there are both solids and gases - xenon, krypton. Fission products have very high radioactivity, so fuel (uranium dioxide pellets) is placed in sealed zirconium tubes - fuel rods (fuel elements). These tubes are combined in 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 of substances that strongly absorb neutrons - for example, boron or cadmium. When the rods are inserted deeply, a chain reaction becomes impossible, since neutrons are strongly absorbed and removed from the reaction zone. The rods are moved remotely from the control panel. With a slight movement of the rods, the chain process will either develop or fade. In this way the power of the reactor is regulated.
The station layout is double-circuit. The first, radioactive, circuit consists of one VVER 1000 reactor and four circulation cooling loops. The second circuit, non-radioactive, includes a steam generator and water supply unit 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 regulate 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 generated during the nuclear reaction.
2. The heated coolant transfers its heat to the secondary circuit water (working fluid), evaporating it in the steam generator.
3. The cooled coolant re-enters the reactor.
4. The steam generator produces saturated steam at a pressure of 6.4 MPa, which is supplied to the steam turbine.
5. The turbine drives the rotor of the electric generator.
6. The exhaust steam is condensed in the condenser and again supplied to the steam generator by the condensate pump. To maintain 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 the feed pump from the cooler 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 not possible 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's operation are ensured by strict adherence to regulations (operating rules) and a large amount of control equipment. All of it is designed for thoughtful and effective management reactor.
Emergency protection of a nuclear reactor is 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 could lead to an accident. Such parameters may include: temperature, pressure and coolant flow, level and speed 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, to shut down the reactor, a liquid absorber is injected into the coolant loop.
In addition to active protection, many modern designs also include elements of passive protection. For example, modern versions of VVER reactors include an “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 first cooling circuit of the reactor), the contents of these tanks end up inside the reactor core by gravity and the nuclear chain reaction is extinguished by a large amount of boron-containing substance, which absorbs neutrons well.
According to the “Nuclear Safety Rules for Reactor Facilities 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 elements. At the AZ signal, the AZ working parts must be activated 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 protection is provided in the range of changes in neutron flux density from 7% to 120% of the nominal:
1. By neutron flux density - no less than three independent channels;
2. According to the rate of increase in neutron flux density - no less than three independent channels.
Each set of emergency protection equipment must be designed in such a way that, over the entire range of changes in technological parameters established in the design of the reactor plant (RP), emergency protection is provided by at least three independent channels for each technological parameter for which protection is necessary.
Control commands of each set for AZ actuators must be transmitted through at least two channels. When one channel in one of the sets of AZ equipment is taken out of operation without taking this set out of operation, an alarm signal should be automatically generated for this channel.
Emergency protection must be triggered at least in the following cases:
1. Upon reaching the AZ setting for neutron flux density.
2. Upon reaching the AZ setting for the rate of increase in neutron flux density.
3. If the voltage disappears in any set of emergency protection equipment and the CPS power supply buses that have not been taken out of operation.
4. In case of failure of any two of the three protection channels for the neutron flux density or for the rate of increase of the neutron flux in any set of AZ equipment that has not been taken out of operation.
5. When the AZ settings are reached by the technological parameters for which protection must be carried out.
6. When triggering the AZ from a key from a block control point (BCP) or a reserve control point (RCP).
The material was prepared by the online editors of 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.
At nuclear power plants there are three mutual transformations of energy forms
Nuclear power
goes into heat
Thermal energy
goes into mechanical
Mechanical energy
converted to electrical
1. Nuclear energy turns into thermal energy
The basis of the station is the reactor - a structurally allocated volume into which nuclear fuel is loaded and where a controlled chain reaction takes place. Uranium-235 is fissile by slow (thermal) neutrons. As a result, it stands out great amount heat.
STEAM GENERATOR
2. Thermal energy turns into mechanical energy
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.
ELECTRIC GENERATOR
3. Mechanical energy is converted into electrical energy
The mechanical energy of the steam is directed to a turbogenerator, where it is converted into electrical energy and then passed through wires to consumers.
What does a nuclear power plant consist of?
A nuclear power plant is a complex of buildings housing technological equipment. The main building is the main building, where the reactor hall is located. It houses the reactor itself, a nuclear fuel holding pool, a reloading machine (for reloading fuel), all of which is monitored by operators from the control room (control room).
The main element of the reactor is the active zone (1). It is housed 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 occur, 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 that houses the turbine hall (2): 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 storing spent nuclear fuel in special pools. In addition, the stations are equipped with elements of a recirculating cooling system - cooling towers (3) (a concrete tower tapering at the top), a cooling pond (a natural reservoir or an artificially created one) and spray pools.
What types of nuclear power plants are there?
Depending on the type of reactor, a nuclear power plant may have 1, 2 or 3 coolant circuits. In Russia, the most widespread are double-circuit nuclear power plants with reactors of the VVER type (water-cooled power reactor).
NPP WITH 1-CIRCUIT REACTORS
NPP WITH 1-CIRCUIT 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-circuit circuit. The single-circuit circuit is relatively simple, but radioactivity in this case spreads to all elements of the unit, which complicates biological protection.
Currently, there are 4 nuclear power plants with single-circuit reactors operating in Russia
NPP WITH 2-CIRCUIT REACTORS
NPP WITH 2-CIRCUIT REACTORS
The double-circuit scheme is used at nuclear power plants with pressurized water reactors of the VVER type. Water is supplied under pressure into the reactor core and heated. The coolant energy is used in the steam generator to generate 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, there are 5 nuclear power plants with double-circuit reactors operating in Russia
NPP WITH 3-CIRCUIT REACTORS
NPP WITH 3-CIRCUIT REACTORS
The three-circuit scheme is used at nuclear power plants with fast neutron reactors with sodium coolant of the BN type. To prevent contact of radioactive sodium with water, a second circuit with non-radioactive sodium is constructed. Thus, the circuit turns out to be three-circuit.
How many of you have seen a nuclear power plant at least from afar? Taking into account the fact that there are only ten operating nuclear power plants in Russia and they are protected bless you, I think the answer in most cases is negative. However, people in LiveJournal, as you know, are experienced. Okay, how many people saw the nuclear power plant from the inside back then? Well, for example, have you felt the body of a nuclear reactor with your own hand? Nobody. I guessed?
Well, today all subscribers of this photo blog have the opportunity to see all these high tech as close as possible. I understand that it’s much more interesting live, 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 from the construction site of the 4th stage of the Novovoronezh NPP. Not far from the existing 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. Construction is being carried out according to the new project "AES-2006", 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 has not yet been 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 can be seen in the previous photo, the dome of the outer containment shell of the seventh power unit is still at the concreting stage, but the reactor building of power unit No. 6 already looks more interesting (see photo below). In total, concreting this dome required more than 2,000 cubic meters of concrete. The diameter of the dome at the base is 44 m, thickness - 1.2 m. Pay attention to the green pipes and the volumetric metal cylinder (weight - 180 tons, diameter - about 25 m, height - 13 m) - these are elements of the passive heat removal system (PHRS ). They are being installed at a Russian nuclear power plant for the first time. In the event of a complete blackout of all nuclear power plant systems (as happened at Fukushima), the PHRS can provide long-term heat removal from the reactor core. 
05
. By far the largest element of a nuclear power plant are cooling towers. In addition, it is one of the most effective devices for cooling water in circulating water supply systems. The high tower creates the very air draft that is necessary for effective cooling of circulating water. Thanks to the high tower, one part of the vapor is returned to the cycle, and the other is carried away by the wind. 
06
. The height of the shell of the cooling tower of power unit No. 6 is 171 meters. It's about 60 floors. Now this structure is the tallest among similar ones ever built in Russia. Its predecessors did not exceed 150 m in height (at the Kalinin NPP). The construction of the structure took more than 10 thousand cubic meters of concrete. 
07
. At the base of the cooling tower (diameter is 134 m) there is a so-called pool bowl. Its upper part is “paved” with irrigation blocks. The sprinkler 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. Essentially, these are lattice modules made of modern polymer materials. 
08
. Naturally, I wanted to take an epic shot of the top, but the already installed sprinkler prevented me from doing this. Therefore, we move to the cooling tower of power unit No. 7. Alas, it was freezing at night and we had a bad time with the elevator ride to the very top. He's frozen. 
09
. Okay, maybe I’ll have the chance to ride to such a high altitude someday, but for now here’s a shot of the irrigation system being installed. 
10
. I was thinking... Or maybe we were simply not allowed to go upstairs for security reasons? 
11
. The entire territory of the construction site is replete with warning, prohibitory and simply propaganda posters and signs. 
12
. OK. We teleport to the central control room (CCR) building.
Well, of course, nowadays everything is controlled using 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 electrical power system and responds to the occurrence of damage and/or abnormal conditions. When damage occurs, the protection system must identify a specific damaged area and turn it off by acting on special power switches designed to interrupt fault currents (short circuit or ground fault). 
15
. Fire extinguishers are placed along each wall. Automatic, of course. 
16
. Next we move to the 220 kV switchgear building (KRUE-220). One of the most photogenic places in the entire nuclear power plant, in my opinion. There is also KRUE-500, but they didn’t show it to us. GIS-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 power units are being built, with the help of GIS-220, electricity is provided directly to the facilities under construction. 
17
. In the AES-2006 project, according to which the sixth and seventh power units are being built, complete 220/500 kV closed-type gas-insulated switchgears with SF6 insulation were used for the first time in the power distribution scheme at distribution substations. Compared to open switchgears, which have so far been used in nuclear energy, the area of a closed one 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 produced at the Novovoronezh NPP to the Unified Energy System. Pay attention to the boxes near the power line poles. 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 produced by JSC Elektrozavod. The first domestic transformer plant, created in 1928, played a colossal role in the industrialization of the country and in the development of domestic energy. Equipment bearing the Elektrozavod brand operates in more than 60 countries around the world. 
21
. Just in case, I’ll 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 voltage of two classes - 220 kV and 500 kV. At the same time, the turbine (more about it later) generates only 24 kV, which is supplied via a current conductor to a block transformer, where it is increased to 500 kV. After which part of the energy capacity is transferred through GIS-500 to the Unified Energy System. The other part goes to autotransformers (those same Hyundais), where it is reduced from 500 kV to 220 kV and through GIS-220 (see above) it also enters the power system. So, as the mentioned block transformer, three single-phase step-up “electric factory” transformers are used (each power is 533 MW, weight – 340 tons). 
22
. If it’s clear, let’s move on to the steam turbine installation of power unit No. 6. Forgive me, my story seems to go from end to beginning (if we proceed from the process of generating electricity), but approximately in this order we walked around the construction site. So I beg your pardon. 
23
. So, the turbine and generator are hidden under the casing. Therefore, I will explain. Actually, a turbine is a unit in which the thermal energy of steam (at 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 - in the desired direction electrical energy. The assembled weight of the machine is more than 2600 tons, its length is 52 meters, and it consists of more than 500 components. To transport this equipment to construction site About 200 trucks were involved. This turbine K-1200–7-3000 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 new generation nuclear power units, which are being built according to the AES-2006 project. On the picture general form turbine shop. Or a turbine hall, if you like. Old-school nuclear scientists call a turbine a machine. 
24
. The turbine condensers are located on the floor below. The capacitor group belongs to the main technological equipment turbine room and, as everyone has already guessed, is designed to convert turbine exhaust steam into liquid. The resulting condensate, after the necessary regeneration, is returned to the steam generator. The weight of the condensing unit equipment, which includes 4 condensers and a piping system, is more than 2000 tons. Inside the capacitors there are about 80 thousand titanium tubes that form a heat transfer surface with total area 100 thousand square meters. 
25
. Got it? Here's an almost cross-section of the turbine building and let's move on. At the very top is an overhead crane. 
26
. We move 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 sealed and inaccessible. 
29
. And in the most natural way, when you get inside, the first thing you do is lift your head and be amazed at the size of the containment dome. Well, and 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 zone equipment (reactor housing, 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
. Then, 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 block with CPS drives (reactor control and protection system) will be installed on it, ensuring sealing of the main connector. 
32
. Nearby we can see the aging pool. Its internal 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 has been reduced, the used fuel is removed from the spent fuel pool to a nuclear industry enterprise engaged in fuel reprocessing and regeneration (storage, disposal or reprocessing). 
33
. And along the wall there are hydraulic reservoirs of the passive core flooding system. They belong to passive safety systems, that is, they operate without the involvement of personnel and the use of external power sources. To simplify, 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, which absorbs neutrons. It is worth noting 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 tanks for the passive flood of the active zone (8 of 12 tanks), each with a volume of 120 cubic meters. 
34
. During future scheduled maintenance and replacement of nuclear fuel, it will be possible to get inside the reactor compartment through a transport lock. It is a 14-meter cylindrical chamber with a diameter of over 9 meters, hermetically sealed on both sides with gate leaves that open alternately. The total weight of the gateway is about 230 tons. 
35
. From the outside of the gateway there is a panoramic view of the entire construction site in general and power unit No. 7 in particular. 
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 only come across technological pipelines. The big green pipe is one of the contours, so we are already very close. 
37
. And here he is. Pressurized water-pressurized pressurized water nuclear reactor model VVER-1200. I won’t delve into the jungle of nuclear fission and nuclear chain reaction (you’re probably already reading diagonally), I’ll only add that inside the reactor there are many fuel elements (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 moved remotely 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. When the rods are inserted deeply, a chain reaction becomes impossible, since neutrons are strongly absorbed and removed from the reaction zone. In this way the power of the reactor is regulated. Now it’s 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 more than 25 thousand cubic meters of water. The main circulation pump also provides cooling of the core in all operating modes of the reactor plant. The installation includes four main circulation pumps. 
39
. Well, to consolidate the material covered, we look at the simplest diagram of the operation of a nuclear power plant. It's simple, isn't it? In particularly advanced cases, re-read the post again, hehe))
40
. In general, it’s something like this. But for those who are close to the topic, I’ll throw in a few more cards with people. Agree, there are not many of them in the report, and yet, since 2006, many thousands of specialists of various profiles have worked here. 
41
. Someone below... 
42
. And someone above... Although you don’t see them, they are there. 
43
. And this is one of the most honored builders of the Novovoronezh NPP - the DEMAG crawler self-propelled crane. It was he who lifted and installed these multi-ton elements of the reactor and turbine halls (load capacity - 1250 tons). The guy-installer and the truck to understand the scale, and at his 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 combined. 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 from the first and second turned into the sixth and seventh, respectively. Info 110%. Those who wish can immediately go to rewrite articles on Wikipedia, and I thank the employees of the department for relations with the NPP power units under construction and especially Tatyana, without whom this excursion most likely would 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 to Vladimir
NUCLEAR POWER PLANT(NPP), a power plant that uses heat released in a nuclear reactor as a result of a controlled chain reaction of fission of nuclei of heavy elements (mainly. $\ce(^(233)U, ^(235)U, ^(239)Pu)$). The heat generated in core nuclear reactor, is transmitted (directly or through an intermediate coolant) working fluid (primarily water steam), 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, while the fundamental thermodynamic schemes of nuclear and thermal power plants are similar, 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 require oxygen to burn fuel; they practically do not pollute environment sulfur dioxide and other gases; nuclear fuel has a significantly higher calorific value (the fission of 1g of U or Pu isotopes releases 22,500 kWh, which is equivalent to the energy contained in 3,000 kg coal), which sharply reduces its volume and costs of transportation and handling; The world's energy resources of nuclear fuel significantly exceed natural reserves of hydrocarbon fuel. In addition, the use of nuclear reactors (of any type) as an energy source requires changes in the thermal circuits 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), spent fuel reloading systems, fuel holding 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, forming the so-called. reactor circuit or loop. Common and heavy water, water vapor, liquid metals, organic liquids, and some gases (for example, helium, carbon dioxide) are used as coolants. 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-circuit circuit (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, such as helium, as a coolant, which is not activated in the neutron field of the core, biological shielding is only necessary around the nuclear reactor, since the coolant is not radioactive. The coolant - the working fluid, heats up in the reactor core, then enters the turbine, where its thermal energy is converted into mechanical energy and then into electrical energy in an electric generator. The most common are single-circuit nuclear power plants with nuclear reactors in which the coolant and neutron moderator water serves. 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 global nuclear energy industry they are designated as BWR (Boiling Water Reactor). Boiling water reactors with a water coolant and a graphite moderator - RBMK (high-power channel reactor) - have become widespread in Russia. The use of high-temperature gas-cooled reactors (with helium coolant) - HTGR - at nuclear power plants is considered promising. The efficiency of single-circuit nuclear power plants operating in a closed gas turbine cycle can exceed 45–50%.
With a double-circuit circuit (Fig. b) the primary circuit 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 a circulation pump. The primary coolant can be water, liquid metal or gas, and the working fluid is water, which turns into water vapor in a steam generator. The primary circuit is radioactive and is surrounded by biological shielding (except in cases where an inert gas is used as a coolant). The second circuit is usually radiation-safe, since the working fluid and the coolant of the first circuit do not come into contact. The most widespread are double-circuit nuclear power plants with reactors in which water is the primary coolant and moderator, and water vapor is the working fluid. This type of reactor is designated as VVER - water-cooled power reactor. reactor (PWR - Power Water Reactor). The efficiency of NPPs with VVER reaches 40%. In terms of thermodynamic efficiency, such nuclear power plants are inferior to single-circuit nuclear power plants with HTGR if the temperature of the gas coolant at the exit from the core exceeds 700 °C.
Three-circuit thermal circuits(rice., V) are used only in cases where it is necessary to completely eliminate contact of the coolant of the primary (radioactive) circuit with the working fluid; for example, when the core is cooled with liquid sodium, its contact with the working fluid (water vapor) 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). The peculiarity 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. 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 steam superheater operating on hydrocarbon fuel - to increase the temperature and pressure. The thermodynamic efficiency of a nuclear power plant cycle is higher, the higher the parameters of the coolant and working fluid, which are determined by the technological capabilities and properties of the structural materials used in the cooling circuits of the nuclear power plant.
At nuclear power plants, great attention is paid to cleaning 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 radiation conditions in the premises of the nuclear power plant.
Nuclear power plants are almost always built near energy consumers, since the costs of transporting nuclear fuel to nuclear power plants, unlike hydrocarbon fuel for thermal power plants, have little effect on the cost of the generated energy (usually nuclear fuel in power reactors is replaced with new one once every few years). years), and the transmission of both electrical and thermal energy over long distances significantly increases their cost. A nuclear power plant is built on the downwind side of the nearest populated area; a sanitary protection zone and an observation zone are created around it, where the population is not allowed to live. Control and measuring equipment is placed in the observation zone for continuous monitoring of the environment.
Nuclear power plant is the basis nuclear power. Their main purpose is the production of electricity (condensing-type nuclear power plants) or the combined production of electricity and heat (nuclear combined heat and power plants - NCHPP). At the ATPP, part of the steam exhausted in the turbines is discharged into the so-called. network heat exchangers for heating water circulating in closed heating networks. In some cases, the thermal energy of nuclear reactors can only be used for district heating needs (nuclear heat supply plants - AST). In this case, heated water from the heat exchangers of the first and second circuits enters the network heat exchanger, where it transfers 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 when qualified. operation of nuclear reactors. Existing radiation safety barriers for nuclear power plants (fuel cladding, nuclear reactor vessel, etc.) prevent contamination of the coolant with radioactive fission products. A protective shell (containment) is erected over the reactor hall of a nuclear power plant to prevent radioactive materials from entering the environment in the event of the most severe accident - depressurization of the primary circuit, melting of the core. Training of NPP personnel involves training on special simulators (NPP simulators) to practice actions in both normal and emergency situations. At a nuclear power plant there are a number of services that ensure the normal functioning of the plant and the safety of its personnel (for example, radiation monitoring, 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 generated during its operation. All this leads to the fact that the cost of an installed kilowatt of power at a nuclear power plant is more than 30% higher than the cost of a kilowatt at a thermal power plant. However, the cost of energy generated at a nuclear power plant supplied to the consumer is lower than at thermal power plants, due to the very small share of the fuel component in this cost. Due to their high efficiency and power regulation features, nuclear power plants are usually used in basic modes, while the installed capacity utilization factor of nuclear power plants can exceed 80%. As the share of nuclear power plants in the overall energy balance of the region increases, they can also operate in a flexible mode (to cover load unevenness 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. Nuclear power plants have been developed whose equipment layout is based on the principles implemented in shipboard nuclear power plants. installations (see Nuclear-powered icebreaker). Such nuclear power plants can be placed, for example, on a barge. Promising nuclear power plants with HTGR are those that generate thermal energy for carrying out technological processes in metallurgical, chemical and oil production, during the gasification of coal and shale, and in the production of synthetic hydrocarbon fuels. The operating life of a nuclear power plant is 25–30 years. Decommissioning of a nuclear power plant, dismantling the reactor and reclamation of its site to the state of a “green lawn” is a complex and expensive organizational and technical event, 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 Obninsk. In 1956, the Calder Hall nuclear power plant in the UK (46 MW) came into operation, and in 1957, the Shippingport nuclear power plant in the USA (60 MW). In 1974, the world's first nuclear power plant, Bilibinskaya (Chukotka Autonomous District), 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 noticeably decreased, and in a number of countries that have sufficient traditional fuel and energy resources of their own or access to them, the construction of new nuclear power plants actually stopped (Russia, USA, Great Britain, Germany). At the beginning of the 21st century, 11.3.2011 in the Pacific Ocean off the eastern 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 village, Fukushima Prefecture) the largesttechnological disaster– radiation accident of the maximum level 7 on the International Nuclear Event Scale. The tsunami impact disabled external power supplies and backup diesel generators, which caused the inoperability of all normal and emergency cooling systems and led to a meltdown of the reactor core at power units 1, 2 and 3 in the early days of the accident. In December 2013, the nuclear power plant was officially closed. As of the first half of 2016, high levels of radiation make it impossible not only for people to work in reactor buildings, but also for robots, which fail due to high levels of radiation. It is planned that the removal of soil layers to special storage facilities and its destruction will take 30 years.
31 countries around the world use nuclear power plants. Valid for 2015 approx. 440 nuclear power reactors (power units) with a total capacity of more than 381 thousand 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 accounts for 76.9%.
The largest nuclear power plant in the world in 2015 (by installed capacity) is Kashiwazaki-Kariwa (Kashiwazaki, Niigata Prefecture, Japan). There are 5 boiling water reactors (BWR) and 2 advanced boiling water reactors (ABWR) in operation, with a combined capacity of 8,212 MW (8.212 GW).
The largest nuclear power plant in Europe is Zaporozhye NPP (Energodar, Zaporozhye region, Ukraine). Since 1996, 6 power units with VVER-1000 type reactors with a total capacity of 6000 MW (6 GW) have been operating.
| Table 1. Largest consumers of nuclear energy 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 USA and Japan are developing mini-nuclear power plants with a capacity of about 10–20 MW for heat and electricity 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 nuclear leakage.
In Russia, as of 2015, there are 10 nuclear power plants operating 34 power units with a total capacity of 24,643 MW (24,643 GW), of which 18 power units with VVER-type reactors (of which 11 power units are VVER-1000 and 6 power units are VVER-440 of various modifications); 15 power units with channel reactors (11 power units with reactors of the RBMK-1000 type and 4 power units with reactors of the EGP-6 type - Energy Heterogeneous Loop Reactor with 6 coolant circulation loops, electrical power 12 MW); 1 power unit with a 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 Nuclear Energy Industry Complex of Russia”, 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. Nuclear power plants operating on the territory of the Russian Federation | ||||
| Name of NPP | 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 bank of the Udomlya River (Tver region)] | 4 | 1984, 1986, 2004, 2011 | 4000 | VVER-1000 |
| Kursk Nuclear Power Plant (near the city of Kurchatov on the left bank of the Seim River) | 4 | 1976, 1979, 1983, 1985 | 4000 | RBMK-1000 |
| Leningrad Nuclear Power Plant (near Sosnovy Bor) | 4 under construction – 4 | 1973, 1975, 1979, 1981 | 4000 | RBMK-1000 (the first station in the country with reactors of this type) |
| Rostov Nuclear Power Plant (located on the shore of the Tsimlyansk Reservoir, 13.5 km from Volgodonsk) | 3 | 2001, 2010, 2015 | 3100 | VVER-1000 |
| Smolensk Nuclear Power Plant (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 Nuclear Power Plant (200 km south of Murmansk on the shore 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 |
Designed nuclear power plants in the Russian Federation
Since 2008, according to the new project AES-2006 (a project of a Russian nuclear power plant of the new generation “3+” with improved technical and economic indicators), Novovoronezh NPP-2 (near the Novovoronezh NPP), which provides for the use of VVER-1200 reactors, has been built. 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 start-up of the first unit (unit No. 6) of Novovoronezh NPP-2 took place in 2016, the second unit No. 7 is planned for 2018.
The Baltic NPP provides for the use of a VVER-1200 reactor unit with a capacity of 1200 MW; power units – 2. Total installed capacity 2300 MW. Commissioning of the first unit is planned for 2020. Federal agency The Russian Nuclear Energy Department is conducting a project to create low-power floating nuclear power plants. The Akademik Lomonosov NPP, which is under construction, will become the world's first floating nuclear power plant. The floating station can be used to generate electrical and thermal energy, as well as to desalinate sea water. It can produce from 40 to 240 thousand m2 of fresh water per day. The installed electrical power of each reactor is 35 MW. The station is planned to be put into operation in 2018.
International projects of Russia in nuclear energy
23.9.2013 Russia transferred the Bushehr nuclear power plant (Bushir) to Iran for operation , near the city of Bushir (Bushir stop); number of power units – 3 (1 built, 2 – under construction); reactor type – VVER-1000. Kudankulam NPP, near Kudankulam (Tamil Nadu, India); number of power units – 4 (1 – in operation, 3 – under construction); reactor type – VVER-1000. Akkuyu NPP, near Mersin (il Mersin, Türkiye); 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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