The principle of operation of the nuclear power plant. Nuclear power plants (NPP)
The principle of operation of a nuclear power plant and power plants that burn conventional fuel (coal, gas, fuel oil, peat) is the same: due to the heat released, water is converted into steam, which is supplied under pressure to a turbine and rotates it. The turbine, in turn, transmits rotation to the electric current generator, which converts mechanical energy rotation into electrical energy, that is, it generates a current. In the case of thermal power plants, the conversion of water into steam occurs due to the energy of combustion of coal, gas, etc., in the case of nuclear power plants, due to the energy of fission of the uranium-235 nucleus.
To convert the energy of nuclear fission into the energy of water vapor, various types of installations are used, which are called nuclear power reactors (installations). Uranium is usually used in the form of dioxide - U0 2 .
Uranium oxide as part of special structures is placed in a moderator - a substance, upon interaction with which neutrons quickly lose energy (slow down). For these purposes, it is used water or graphite - accordingly, the reactors are called water or graphite.
To transfer energy (in other words, heat) from the core to the turbine, a coolant is used - water, liquid metal(e.g. sodium) or gas(for example, air or helium). The coolant washes the heated hermetic structures from the outside, inside which the fission reaction takes place. As a result of this, the coolant heats up and, moving through special pipes, transfers energy (in the form of its own heat). The heated coolant is used to create steam, which is supplied to the turbine under high pressure.
Fig.G.1. circuit diagram NPP: 1 - nuclear reactor, 2 - circulation pump, 3 - heat exchanger, 4 - turbine, 5 - electric current generator
In the case of a gas coolant, this stage is absent, and the heated gas is fed directly to the turbine.
In the Russian (Soviet) nuclear power industry, two types of reactors have become widespread: the so-called Reactor Big Power Channel (RBMK) and Pressurized Water Power Reactor (VVER). Using the RBKM as an example, we will consider the principle of operation of a nuclear power plant in a little more detail.
RBMK
RBMK is a source of electricity with a capacity of 1000 MW, which reflects the entry RBMK-1000. The reactor is placed in a reinforced concrete shaft on a special supporting structure. Around him, above and below is located biological protection(protection against ionizing radiation). Fills the reactor core graphite masonry(that is, graphite blocks 25x25x50 cm in size folded in a certain way) of a cylindrical shape. Vertical holes are made along the entire height (Fig. G.2.). Metal pipes are placed in them, called channels(hence the name "channel"). Either structures with fuel (TVEL - fuel element) or rods for controlling the reactor are installed in the channels. The first are called fuel channels, the second - channels of control and protection. Each channel is an independent sealed structure. The reactor is controlled by immersing rods into the channel that absorb neutrons (for this purpose, materials such as cadmium, boron, and europium are used). The deeper such a rod enters the core, the more neutrons are absorbed, therefore, the number of fissile nuclei decreases, and the energy release decreases. The set of relevant mechanisms is called control and protection system (CPS).
Fig.G.2. RBMK scheme.
Water is supplied to each fuel channel from below, which is supplied to the reactor by a special powerful pump - it is called main circulation pump (MCP). Washing the fuel assemblies, the water boils, and a steam-water mixture is formed at the outlet of the channel. She enters separator drum (BS)- an apparatus that allows you to separate (separate) dry steam from water. The separated water is sent by the main circulation pump back to the reactor, thereby closing the circuit "reactor - drum-separator - SSC - reactor". It is called circuit of multiple forced circulation (KMPTS). There are two such circuits in the RBMK.
The amount of uranium oxide required for the operation of the RBMK is about 200 tons (using them releases the same energy as burning about 5 million tons of coal). The fuel "works" in the reactor for 3-5 years.
The coolant is in closed loop, isolated from external environment, excluding any significant radiation contamination. This is confirmed by studies of the radiation situation around the nuclear power plant, both by the services of the stations themselves, and by regulatory authorities, environmentalists, and international organizations.
Cooling water comes from a reservoir near the station. At the same time, the water taken in has a natural temperature, and the water coming back into the reservoir is approximately 10 ° C higher. There are strict regulations on heating temperature, which are further tightened to take into account local ecosystems, but the so-called "thermal pollution" of the reservoir is probably the most significant environmental damage from nuclear power plants. This disadvantage is not fundamental and insurmountable. To avoid it, along with cooling ponds (or instead of them), cooling towers. They are huge structures in the form of conical pipes of large diameter. Cooling water, after heating in the condenser, is fed into numerous tubes located inside the cooling tower. These tubes have small holes through which water flows out, forming a "giant shower" inside the cooling tower. The falling water is cooled by atmospheric air and collected under the cooling tower in the pool, from where it is taken to cool the condenser. Above the cooling tower, as a result of the evaporation of water, a white cloud forms.
Radioactive emissions from nuclear power plants 1-2 orders below the maximum permissible (that is, acceptably safe) values, and the concentration of radionuclides in the areas of the NPP millions of times less than the MPC and tens of thousands of times less than the natural level of radioactivity.
Radionuclides entering the environment during NPP operation are mainly fission products. The bulk of them are inert radioactive gases (IRG), which have short periods half-life and therefore do not have a tangible impact on the environment (they decay before they have time to act). In addition to fission products, some of the emissions are activation products (radionuclides formed from stable atoms under the action of neutrons). Significant in terms of radiation exposure are long lived radionuclides(JN, the main dose-forming radionuclides are cesium-137, strontium-90, chromium-51, manganese-54, cobalt-60) and radioisotopes of iodine(mainly iodine-131). At the same time, their share in NPP emissions is extremely insignificant and amounts to thousandths of a percent.
According to the results of 1999, releases of radionuclides from nuclear power plants in terms of inert radioactive gases did not exceed 2.8% of the permissible values for uranium-graphite reactors and 0.3% for VVER and BN. For long-lived radionuclides, emissions did not exceed 1.5% of the allowable emissions for uranium-graphite reactors and 0.3% for VVER and BN, for iodine-131, respectively, 1.6% and 0.4%.
An important argument in favor of nuclear energy is the compactness of the fuel. Rounded estimates are as follows: 1 kWh of electricity can be produced from 1 kg of firewood, 3 kWh from 1 kg of coal, 4 kWh from 1 kg of oil, and 300,000 kWh from 1 kg of nuclear fuel (low-enriched uranium). h.
BUT languid power unit power of 1 GW consumes approximately 30 tons of low-enriched uranium per year (that is, approximately one car per year). To ensure a year of operation of the same power coal power plant about 3 million tons of coal are needed (that is, about five trains per day).
Releases of long-lived radionuclides coal-fired or oil-fired power plants on average, 20-50 (and according to some estimates, 100) times higher than nuclear power plants of the same capacity.
Coal and other fossil fuels contain potassium-40, uranium-238, thorium-232, the specific activity of each of which ranges from several units to several hundred Bq / kg (and, accordingly, such members of their radioactive series as radium-226, radium -228, lead-210, polonium-210, radon-222 and other radionuclides). Isolated from the biosphere in the thickness of the earth's rock, when coal, oil and gas are burned, they are released and released into the atmosphere. Moreover, these are mainly the most dangerous alpha-active nuclides from the point of view of internal exposure. And although the natural radioactivity of coal is usually relatively low, number fuel burned per unit of energy produced is colossal.
As a result of the exposure dose to the population living near a coal-fired power plant (with the degree of purification of smoke emissions at the level of 98-99%) more than the exposure doses of the population near the nuclear power plant 3-5 times.
In addition to emissions into the atmosphere, it should be taken into account that in places where waste from coal plants is concentrated, a significant increase in the radiation background is observed, which can lead to doses exceeding the maximum allowable. Part of the natural activity of coal is concentrated in ash, which accumulates in huge quantities in power plants. At the same time, levels of more than 400 Bq/kg are noted in ash samples from the Kansko-Achinsk deposit. The radioactivity of the fly ash of the Donbas hard coal exceeds 1000 Bq/kg. And these wastes are not isolated from the environment. The production of a GW-year of electricity from coal combustion releases hundreds of GBq of activity (mostly alpha) into the environment.
Such concepts as "the radiation quality of oil and gas" began to attract serious attention relatively recently, while the content of natural radionuclides in them (radium, thorium, and others) can reach significant values. For example, the volumetric activity of radon-222 in natural gas is on average from 300 to 20,000 Bq / m 3 with maximum values up to 30,000-50,000. And Russia produces almost 600 billion such cubic meters per year.
Nevertheless, it should be noted that radioactive emissions from both nuclear power plants and thermal power plants do not lead to noticeable consequences for public health. Even for coal-fired power plants, this is a third-rate environmental factor, which is significantly lower in significance than others: chemical and aerosol emissions, waste, and so on.
APPENDIX H
The nuclear reactor works smoothly and accurately. Otherwise, as you know, there will be trouble. But what's going on inside? Let's try to formulate the principle of operation of a nuclear (atomic) reactor briefly, clearly, with stops.
In fact, the same process is going on there as in a nuclear explosion. Only now the explosion occurs very quickly, and in the reactor all this stretches for a long time. In the end, everything remains safe and sound, and we get energy. Not so much that everything around immediately smashed, but quite enough to provide electricity to the city.
Before understanding how the managed nuclear reaction need to know what is nuclear reaction at all.
nuclear reaction - this is the process of transformation (fission) of atomic nuclei during their interaction with elementary particles and gamma quanta.
Nuclear reactions can take place both with absorption and with the release of energy. Second reactions are used in the reactor.
Nuclear reactor - This is a device whose purpose is to maintain a controlled nuclear reaction with the release of energy.
Often a nuclear reactor is also called a nuclear reactor. Note that there is no fundamental difference here, but from the point of view of science, it is more correct to use the word "nuclear". There are now many types of nuclear reactors. These are huge industrial reactors designed to generate energy at power plants, nuclear reactors submarines, small experimental reactors used in scientific experiments. There are even reactors used to desalinate seawater.
The history of the creation of a nuclear reactor
The first nuclear reactor was launched in the not so distant 1942. It happened in the USA under the leadership of Fermi. This reactor was called the "Chicago woodpile".
In 1946, the first Soviet reactor started up under the leadership of Kurchatov. The body of this reactor was a ball seven meters in diameter. The first reactors did not have a cooling system, and their power was minimal. By the way, the Soviet reactor had an average power of 20 watts, while the American one had only 1 watt. For comparison: the average power of modern power reactors is 5 Gigawatts. Less than ten years after the launch of the first reactor, the world's first industrial nuclear power plant in the city of Obninsk.
The principle of operation of a nuclear (atomic) reactor
Anyone nuclear reactor there are several parts: core from fuel And moderator , neutron reflector , coolant , control and protection system . Isotopes are the most commonly used fuel in reactors. uranium (235, 238, 233), plutonium (239) and thorium (232). The active zone is a boiler through which ordinary water (coolant) flows. Among other coolants, “heavy water” and liquid graphite are less commonly used. If we talk about the operation of a nuclear power plant, then a nuclear reactor is used to generate heat. The electricity itself is generated by the same method as in other types of power plants - steam rotates the turbine, and the energy of movement is converted into electrical energy.
Below is a diagram of the operation of a nuclear reactor.
As we have already said, the decay of a heavy uranium nucleus produces lighter elements and a few neutrons. The resulting neutrons collide with other nuclei, also causing them to fission. In this case, the number of neutrons grows like an avalanche.
It needs to be mentioned here neutron multiplication factor . So, if this coefficient exceeds a value equal to one, a nuclear explosion occurs. If the value is less than one, there are too few neutrons and the reaction dies out. But if you maintain the value of the coefficient equal to one, the reaction will proceed for a long time and stably.
The question is how to do it? In the reactor, the fuel is in the so-called fuel elements (TVELah). These are rods in which, in the form of small tablets, nuclear fuel . The fuel rods are connected into hexagonal cassettes, of which there can be hundreds in the reactor. Cassettes with fuel rods are located vertically, while each fuel rod has a system that allows you to adjust the depth of its immersion in the core. In addition to the cassettes themselves, among them are control rods And emergency protection rods . The rods are made of a material that absorbs neutrons well. Thus, the control rods can be lowered to different depths in the core, thereby adjusting the neutron multiplication factor. The emergency rods are designed to shut down the reactor in the event of an emergency.
How is a nuclear reactor started?
We figured out the very principle of operation, but how to start and make the reactor function? Roughly speaking, here it is - a piece of uranium, but after all, a chain reaction does not start in it by itself. The fact is that in nuclear physics there is a concept critical mass .
Critical mass is the mass of fissile material necessary to start a nuclear chain reaction.
With the help of fuel elements and control rods, a critical mass of nuclear fuel is first created in the reactor, and then the reactor is brought to the optimal power level in several stages.
In this article, we have tried to give you a general idea of the structure and principle of operation of a nuclear (atomic) reactor. If you have any questions on the topic or the university asked a problem in nuclear physics, please contact specialists of our company. We, as usual, are ready to help you solve any pressing issue of your studies. In the meantime, we are doing this, your attention is another educational video!
To understand the principle of operation and design of a nuclear reactor, you need to make a short digression into the past. A nuclear reactor is a centuries-old embodied, albeit not completely, dream of mankind about an inexhaustible source of energy. Its ancient "progenitor" is a fire made of dry branches, which once illuminated and warmed the vaults of the cave, where our distant ancestors found salvation from the cold. Later, people mastered hydrocarbons - coal, shale, oil and natural gas.
A turbulent but short-lived era of steam began, which was replaced by an even more fantastic era of electricity. The cities were filled with light, and the workshops with the hum of hitherto unknown machines driven by electric motors. Then it seemed that progress had reached its climax.
Everything changed at the end of the 19th century, when the French chemist Antoine Henri Becquerel accidentally discovered that uranium salts are radioactive. After 2 years, his compatriots Pierre Curie and his wife Maria Sklodowska-Curie obtained radium and polonium from them, and their level of radioactivity was millions of times higher than that of thorium and uranium.
The baton was picked up by Ernest Rutherford, who studied in detail the nature of radioactive rays. Thus began the age of the atom, which gave birth to its beloved child - the nuclear reactor.
First nuclear reactor
The "firstborn" is from the USA. In December 1942, the reactor gave the first current, which got the name of its creator, one of the greatest physicists of the century, E. Fermi. Three years later, the ZEEP nuclear plant came to life in Canada. "Bronze" went to the first Soviet reactor F-1, launched at the end of 1946. I. V. Kurchatov became the head of the domestic nuclear project. Today, more than 400 nuclear power units are successfully operating in the world.
Types of nuclear reactors
Their main purpose is to support a controlled nuclear reaction that produces electricity. Some reactors produce isotopes. In short, they are devices in the depths of which some substances are converted into others with the release of a large amount of thermal energy. This is a kind of "furnace", where instead of traditional fuels, uranium isotopes - U-235, U-238 and plutonium (Pu) are "burned".
Unlike, for example, a car designed for several types of gasoline, each type of radioactive fuel has its own type of reactor. There are two of them - on slow (with U-235) and fast (with U-238 and Pu) neutrons. Most nuclear power plants are equipped with slow neutron reactors. In addition to nuclear power plants, installations "work" in research centers, on nuclear submarines and.
How is the reactor
All reactors have approximately the same scheme. Its "heart" is the active zone. It can be roughly compared with the furnace of a conventional stove. Only instead of firewood there is nuclear fuel in the form of fuel elements with a moderator - TVELs. The active zone is located inside a kind of capsule - a neutron reflector. The fuel rods are "washed" by the coolant - water. Since the “heart” has a very high level of radioactivity, it is surrounded by reliable radiation protection.
The operators control the operation of the plant with the help of two critical systems, the chain reaction control and the remote control system. If an emergency situation arises, emergency protection is instantly triggered.
How the reactor works
The atomic "flame" is invisible, since the processes occur at the level of nuclear fission. In the course of a chain reaction, heavy nuclei break up into smaller fragments, which, being in an excited state, become sources of neutrons and other subatomic particles. But the process does not end there. Neutrons continue to “crush”, as a result of which a lot of energy is released, that is, what happens for which nuclear power plants are built.
The main task of the staff is to maintain a chain reaction with the help of control rods at a constant, adjustable level. This is its main difference from atomic bomb, where the process of nuclear decay is uncontrollable and proceeds rapidly, in the form of a powerful explosion.
What happened at the Chernobyl nuclear power plant
One of the main causes of the catastrophe at the Chernobyl nuclear power plant in April 1986 was a gross violation of operational safety rules in the process of routine maintenance at the 4th power unit. Then 203 graphite rods were removed from the core at the same time instead of the 15 allowed by the regulations. As a result, the uncontrolled chain reaction that began ended in a thermal explosion and the complete destruction of the power unit.
New generation reactors
Over the past decade, Russia has become one of the world's nuclear power leaders. On the this moment Rosatom State Corporation is building nuclear power plants in 12 countries, where 34 power units are being built. So high demand- evidence of the high level of modern Russian nuclear technology. Next in line are the new 4th generation reactors.
"Brest"
One of them is Brest, which is being developed as part of the Breakthrough project. Current open-cycle systems run on low-enriched uranium, leaving a large amount of spent fuel to be disposed of at a huge cost. "Brest" - reactor fast neutrons unique closed loop.
In it, the spent fuel, after appropriate processing in a fast neutron reactor, again becomes a full-fledged fuel that can be loaded back into the same facility.
Brest is distinguished by a high level of security. It will never "explode" even in the most serious accident, it is very economical and environmentally friendly, since it reuses its "renewed" uranium. It also cannot be used to produce weapons-grade plutonium, which opens up the broadest prospects for its export.
VVER-1200
VVER-1200 is an innovative generation 3+ reactor with a capacity of 1150 MW. Thanks to its unique technical capabilities, it has almost absolute operational safety. The reactor is equipped with passive safety systems in abundance, which will work even in the absence of power supply in automatic mode.
One of them is a passive heat removal system, which is automatically activated when the reactor is completely de-energized. In this case, emergency hydraulic tanks are provided. With an abnormal pressure drop in the primary circuit, a large amount of water containing boron is supplied to the reactor, which quenches the nuclear reaction and absorbs neutrons.
Another know-how is located in the lower part of the containment - the "trap" of the melt. If, nevertheless, as a result of an accident, the core "leaks", the "trap" will not allow the containment to collapse and prevent the ingress of radioactive products into the ground.
The proposal to create an AM reactor for a future nuclear power plant was first made on November 29, 1949 at a meeting of the supervisor nuclear project I.V. Kurchatov, director of the Institute of Physical Problems A.P. Aleksandrov, director of NIIKhimash N.A. Dollezhal and scientific secretary of the NTS of the industry B.S. Pozdnyakov. The meeting recommended to include in the PSU R&D plan for 1950 “a project of an enriched uranium reactor with small dimensions only for power purposes with a total heat release capacity of 300 units, an effective power of about 50 units” with graphite and a water coolant. At the same time, instructions were given to urgently carry out physical calculations and experimental studies on this reactor.
Later I.V. Kurchatov and A.P. Zavenyagin explained the choice of the AM reactor for high-priority construction by the fact that "it can be more than in other units, the experience of conventional boiler practice is used: the overall relative simplicity of the unit facilitates and reduces the cost of construction."
During this period, options for the use of power reactors are being discussed at various levels.
PROJECT
It was considered expedient to start with the creation of a reactor for a ship power plant. In order to justify the design of this reactor and to “confirm in principle ... the practical possibility of converting the heat of nuclear reactions of nuclear installations into mechanical and electrical energy”, it was decided to build in Obninsk, on the territory of Laboratory “V”, a nuclear power plant with three reactor installations, including and the AM plant, which became the reactor of the First NPP).
By the Decree of the Council of Ministers of the USSR of May 16, 1950, R&D in AM was entrusted to LIPAN (I.V. Kurchatov Institute), NIIKhimmash, GSPI-11, VTI). In 1950 - early 1951. these organizations carried out preliminary calculations (P.E. Nemirovskii, S.M. Feinberg, Yu.N. Zankov), preliminary design studies, etc., then all work on this reactor was, by decision of I.V. Kurchatov, transferred to the Laboratory "B". Appointed scientific supervisor, chief designer - N.A. Dollezhal.
The design provided for the following parameters of the reactor: thermal power 30 thousand kW, electric power - 5 thousand kW, reactor type - thermal neutron reactor with graphite moderator and cooling with natural water.
By this time, the country already had experience in creating reactors of this type (industrial reactors for the production of bomb material), but they differed significantly from power plants, which include the AM reactor. Difficulties were associated with the need to obtain high coolant temperatures in the AM reactor, from which it followed that it was necessary to search for new materials and alloys that can withstand these temperatures, are resistant to corrosion, do not absorb neutrons in large quantities, etc. For the initiators of the construction of a nuclear power plant with an AM reactor these problems were obvious from the beginning, the question was how soon and how successfully they could be overcome.
CALCULATIONS AND STAND
By the time the work on AM was handed over to Laboratory "B", the project was defined only in general terms. There were many physical, technical and technological problems to be solved, and their number increased as the work on the reactor progressed.
First of all, this concerned the physical calculations of the reactor, which had to be carried out without many of the data necessary for this. In Laboratory "V" D.F. Zaretsky, and the main calculations were carried out by the group of M.E. Minashina in the department of A.K. Krasin. M.E. Minashin was especially concerned about the lack of precise values for many of the constants. It was difficult to organize their measurement on the spot. On his initiative, some of them were gradually replenished mainly due to measurements carried out by LIPAN and a few in Laboratory "B", but in general it was impossible to guarantee the high accuracy of the calculated parameters. Therefore, at the end of February - beginning of March 1954, the AMF stand was assembled - a critical assembly of the AM reactor, which confirmed the satisfactory quality of the calculations. And although the assembly could not reproduce all the conditions of a real reactor, the results supported the hope of success, although there were many doubts.
On March 3, 1954, a chain reaction of uranium fission was carried out on this stand for the first time in Obninsk.
But, taking into account that the experimental data were constantly refined, the calculation methodology was improved, until the launch of the reactor, the study of the amount of loading of the reactor with fuel, the behavior of the reactor in non-standard modes, the parameters of the absorbing rods, etc., continued.
CREATION OF A TVEL
With another important task - the creation of a fuel element (fuel element) - V.A. Malykh and the staff of the technological department of the Laboratory "V". The development of the fuel rod was carried out by several related organizations, but only the variant proposed by V.A. Small, showed high performance. The design search was completed at the end of 1952 by the development of a new type of fuel element (with a dispersion composition of uranium-molybdenum grains in a magnesium matrix).
This type of fuel element made it possible to reject them during pre-reactor tests (special benches were created in Laboratory V for this purpose), which is very important for ensuring the reliable operation of the reactor. The stability of a new fuel element in a neutron flux was studied at LIPAN at the MR reactor. NIIKhimmash developed the working channels of the reactor.
So for the first time in our country, perhaps the most important and most difficult problem of the emerging nuclear energy– creation of a fuel element.
CONSTRUCTION
In 1951, simultaneously with the beginning in the Laboratory "B" research work on the AM reactor, the construction of a nuclear power plant building began on its territory.
P.I. was appointed head of construction. Zakharov, chief engineer of the facility -.
As D.I. Blokhintsev, “the nuclear power plant building in its most important parts had thick walls made of reinforced concrete monolith to provide biological protection from nuclear radiation. Pipelines, cable channels, ventilation, etc. were laid in the walls. It is clear that alterations were not possible, and therefore, when designing the building, reserves were provided, if possible, with the expectation of changes. For the development of new types of equipment and for the implementation of research work, scientific and technical assignments were given for " third parties» - institutes, design bureaus and enterprises. Often these tasks themselves could not be complete and were refined and supplemented as the design progressed. The main engineering and design solutions ... were developed by a design team led by N.A. Dollezhal and his closest assistant P.I. Aleshchenkov ... "
The style of work on the construction of the first nuclear power plant was characterized by quick decision-making, the speed of development, a certain developed depth of primary studies and ways to refine the adopted technical solutions, a wide coverage of variant and insurance directions. The first nuclear power plant was built in three years.
START
At the beginning of 1954, testing and testing began various systems stations.
On May 9, 1954, the loading of the nuclear power plant reactor core with fuel channels began in Laboratory "B". When introducing the 61st fuel channel, a critical state was reached, at 19:40. A chain self-sustaining reaction of fission of uranium nuclei began in the reactor. The physical launch of the nuclear power plant took place.
Recalling the launch, he wrote: “Gradually, the power of the reactor increased, and finally, somewhere near the CHP building, where steam was supplied from the reactor, we saw a jet escaping from the valve with a loud hiss. A white cloud of ordinary steam, and besides, not yet hot enough to rotate the turbine, seemed to us a miracle: after all, this is the first steam obtained at atomic energy. His appearance was the occasion for hugs, congratulations "on a light steam" and even tears of joy. Our jubilation was shared by I.V. Kurchatov, who took part in the work in those days. After receiving steam with a pressure of 12 atm. and at a temperature of 260 °C, it became possible to study all the units of the nuclear power plant under conditions close to the design ones, and on June 26, 1954, in the evening shift, at 17:00. 45 min., the valve for supplying steam to the turbogenerator was opened, and it began to generate electricity from a nuclear boiler. The world's first nuclear power plant has come under industrial load."
“In the Soviet Union, the efforts of scientists and engineers have successfully completed the design and construction of the first industrial nuclear power plant with a useful capacity of 5,000 kilowatts. On June 27, the nuclear power plant was put into operation and provided electricity for industry and Agriculture surrounding areas."
Even before the launch, the first program of experimental work at the AM reactor was prepared, and until the plant was closed, it was one of the main reactor bases, where neutron-physics research, research in solid state physics, testing of fuel rods, EGC, production of isotope products, etc. The crews of the first nuclear submarines were trained at the NPP, nuclear icebreaker"Lenin", personnel of Soviet and foreign nuclear power plants.
The launch of the nuclear power plant for the young staff of the institute was the first test of readiness to solve new and more complex problems. In the initial months of work, individual units and systems were adjusted, the physical characteristics of the reactor, the thermal regime of the equipment and the entire station were studied in detail, various devices were finalized and corrected. In October 1954, the station was brought to its design capacity.
“London, July 1 (TASS). The announcement of the commissioning of the first industrial nuclear power plant in the USSR is widely noted in the English press, the Moscow correspondent of The Daily Worker writes that this historic event "has immeasurably greater value than dropping the first atomic bomb on Hiroshima.
Paris, July 1 (TASS). The London correspondent of Agence France-Presse reports that the announcement of the commissioning in the USSR of the world's first industrial power plant operating on atomic energy was received with great interest in London circles of atomic specialists. England, the correspondent continues, is building a nuclear power plant at Calderhall. It is believed that she will be able to enter service no earlier than in 2.5 years ...
Shanghai, July 1 (TASS). Responding to the commissioning of a Soviet nuclear power plant, Tokyo radio broadcasts: The USA and Britain are also planning the construction of nuclear power plants, but they plan to complete their construction in 1956-1957. That circumstance, that Soviet Union ahead of England and America in the use of atomic energy for peaceful purposes, indicates that Soviet scientists have achieved great success in the field of atomic energy. One of the outstanding Japanese experts in the field of nuclear physics, Professor Yoshio Fujioka, commenting on the announcement of the launch of an atomic power plant in the USSR, said that this was the beginning of a "new era".
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.
Heat in the reactor is released due to the chain reaction of fission of 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 high-purity non-boiling water at 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 supplied to 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 big amount 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 projects 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 protection is provided in the range of neutron flux density from 7% to 120% of the nominal value:
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 parameters change 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 reserve control point (RCR).
The material was prepared by the online editors www.rian.ru based on information from RIA Novosti and open sources
