What does a nuclear reactor look like? School encyclopedia

In the mid-twentieth century, humanity's attention was focused around the atom and scientists' explanation of the nuclear reaction, which they initially decided to use for military purposes, inventing the first nuclear bombs according to the Manhattan Project. But in the 50s of the 20th century, the nuclear reactor in the USSR was used for peaceful purposes. It is well known that on June 27, 1954, the world's first nuclear power plant with a capacity of 5000 kW entered the service of humanity. Today, a nuclear reactor makes it possible to generate electricity of 4000 MW or more, that is, 800 times more than half a century ago.

What is a nuclear reactor: basic definition and main components of the unit

A nuclear reactor is a special unit that produces energy as a result of properly maintaining a controlled nuclear reaction. It is allowed to use the word “atomic” in combination with the word “reactor”. Many generally consider the concepts “nuclear” and “atomic” to be synonymous, since they do not find a fundamental difference between them. But representatives of science are inclined to a more correct combination - “nuclear reactor”.

Interesting fact! Nuclear reactions can occur with the release or absorption of energy.

The main components in the design of a nuclear reactor are the following elements:

• Moderator;
• Control rods;
• Rods containing an enriched mixture of uranium isotopes;
• Special protective elements against radiation;
• Coolant;
• Steam generator;
• Turbine;
• Generator;
• Capacitor;
• Nuclear fuel.

What fundamental principles of the operation of a nuclear reactor are determined by physicists and why they are unshakable

The fundamental operating principle of a nuclear reactor is based on the peculiarities of the manifestation of a nuclear reaction. At the moment of a standard physical chain nuclear process, a particle interacts with an atomic nucleus, as a result, the nucleus turns into a new one with the release of secondary particles, which scientists call gamma quanta. During a nuclear chain reaction, enormous amounts of thermal energy are released. The space in which the chain reaction occurs is called the reactor core.

Interesting fact! The active zone externally resembles a boiler through which ordinary water flows, acting as a coolant.

To prevent the loss of neutrons, the reactor core area is surrounded by a special neutron reflector. Its primary task is to reject most of the emitted neutrons into the core. The same substance that serves as a moderator is usually used as a reflector.

The main control of a nuclear reactor occurs using special control rods. It is known that these rods are introduced into the reactor core and create all the conditions for the operation of the unit. Typically control rods are made from the chemical compounds boron and cadmium. Why are these particular elements used? Yes, all because boron or cadmium are able to effectively absorb thermal neutrons. And as soon as the launch is planned, according to the operating principle of a nuclear reactor, control rods are inserted into the core. Their primary task is to absorb a significant portion of neutrons, thereby provoking the development of a chain reaction. The result should reach the desired level. When the power increases above the set level, automatic machines are switched on, necessarily immersing the control rods deep into the reactor core.

Thus, it becomes clear that control or control rods play an important role in the operation of a thermal nuclear reactor.

And to reduce neutron leakage, the reactor core is surrounded by a neutron reflector, which throws a significant mass of freely escaping neutrons into the core. The reflector usually uses the same substance as the moderator.

According to the standard, the nucleus of the atoms of the moderator substance has a relatively small mass, so that when colliding with a light nucleus, the neutron present in the chain loses more energy than when colliding with a heavy one. The most common moderators are ordinary water or graphite.

Interesting fact! Neutrons in the process of a nuclear reaction are characterized by an extremely high speed of movement, which is why a moderator is required to encourage the neutrons to lose some of their energy.

Not a single reactor in the world can function normally without the help of a coolant, since its purpose is to remove the energy that is generated in the heart of the reactor. Liquid or gases must be used as a coolant, since they are not capable of absorbing neutrons. Let's give an example of a coolant for a compact nuclear reactor - water, carbon dioxide, and sometimes even liquid sodium metal.

Thus, the principles of operation of a nuclear reactor are entirely based on the laws of the chain reaction and its course. All components of the reactor - moderator, rods, coolant, nuclear fuel - perform their assigned tasks, ensuring the normal operation of the reactor.

What fuel is used for nuclear reactors and why these chemical elements are chosen

The main fuel in reactors can be isotopes of uranium, plutonium or thorium.

Back in 1934, F. Joliot-Curie, having observed the process of fission of the uranium nucleus, noticed that as a result of a chemical reaction, the uranium nucleus is divided into fragments-nuclei and two or three free neutrons. This means that there is a possibility that free neutrons will join other uranium nuclei and trigger another fission. And so, as the chain reaction predicts: six to nine neutrons will be released from three uranium nuclei, and they will again join the newly formed nuclei. And so on ad infinitum.

Important to remember! Neutrons appearing during nuclear fission are capable of provoking the fission of nuclei of the uranium isotope with a mass number of 235, and to destroy the nuclei of a uranium isotope with a mass number of 238, the energy generated during the decay process may be insufficient.

Uranium number 235 is rarely found in nature. Its share accounts for only 0.7%, but natural uranium-238 occupies a more spacious niche and makes up 99.3%.

Despite such a small proportion of uranium-235 in nature, physicists and chemists still cannot refuse it, because it is most effective for the operation of a nuclear reactor, reducing the cost of energy production for humanity.

When did the first nuclear reactors appear and where are they commonly used today?

Back in 1919, physicists had already triumphed when Rutherford discovered and described the process of formation of moving protons as a result of the collision of alpha particles with the nuclei of nitrogen atoms. This discovery meant that a nitrogen isotope nucleus, as a result of a collision with an alpha particle, was transformed into an oxygen isotope nucleus.

Before the first nuclear reactors appeared, the world learned several new laws of physics that deal with all the important aspects of nuclear reactions. Thus, in 1934, F. Joliot-Curie, H. Halban, L. Kowarski first proposed to society and the circle of world scientists a theoretical assumption and evidence base about the possibility of carrying out nuclear reactions. All experiments were related to the observation of the fission of a uranium nucleus.

In 1939, E. Fermi, I. Joliot-Curie, O. Gan, O. Frisch tracked the fission reaction of uranium nuclei when bombarded with neutrons. During the research, scientists found that when one accelerated neutron hits a uranium nucleus, the existing nucleus is divided into two or three parts.

The chain reaction was practically proven in the middle of the 20th century. Scientists managed to prove in 1939 that the fission of one uranium nucleus releases about 200 MeV of energy. But approximately 165 MeV is allocated to the kinetic energy of fragment nuclei, and the remainder is carried away by gamma quanta. This discovery made a breakthrough in quantum physics.

E. Fermi continued his work and research for several more years and launched the first nuclear reactor in 1942 in the USA. The implemented project was named “Chicago Woodpile” and was put on the rails. On September 5, 1945, Canada launched its ZEEP nuclear reactor. The European continent was not far behind, and at the same time the F-1 installation was being built. And for Russians there is another memorable date - December 25, 1946 in Moscow, under the leadership of I. Kurchatov, the reactor was launched. These were not the most powerful nuclear reactors, but it was the beginning of man's mastery of the atom.

For peaceful purposes, a scientific nuclear reactor was created in 1954 in the USSR. The world's first peaceful ship with a nuclear power plant, the nuclear-powered icebreaker Lenin, was built in the Soviet Union in 1959. And another achievement of our state is the nuclear icebreaker “Arktika”. This surface ship was the first in the world to reach the North Pole. This happened in 1975.

The first portable nuclear reactors used slow neutrons.

Where are nuclear reactors used and what types does humanity use?

• Industrial reactors. They are used to generate energy at nuclear power plants.
• Nuclear reactors acting as propulsion units for nuclear submarines.
• Experimental (portable, small) reactors. Without them, not a single modern scientific experiment or research takes place.

Today, the scientific world has learned to use special reactors to desalinate sea water and provide the population with high-quality drinking water. There are a lot of operating nuclear reactors in Russia. Thus, according to statistics, as of 2018, about 37 units operate in the state.

And according to classification they can be as follows:

• Research (historical). These include the F-1 station, which was created as an experimental site for the production of plutonium. I.V. Kurchatov worked at F-1 and led the first physical reactor.
• Research (active).
• Armory. As an example of a reactor - A-1, which went down in history as the first reactor with cooling. The past power of the nuclear reactor is small, but functional.
• Energy.
• Ship's. It is known that on ships and submarines, out of necessity and technical feasibility, water-cooled or liquid metal reactors are used.
• Space. As an example, let's call the Yenisei installation on spacecraft, which comes into operation if it is necessary to extract additional energy, and it will have to be obtained using solar panels and isotope sources.

Thus, the topic of nuclear reactors is quite extensive, and therefore requires in-depth study and understanding of the laws of quantum physics. But the importance of nuclear reactors for the energy and economy of the state is already, undoubtedly, surrounded by an aura of usefulness and benefit.

Design and principle of operation

Energy release mechanism

The transformation of a substance is accompanied by the release of free energy only if the substance has a reserve of energy. The latter means that microparticles of a substance are in a state with a rest energy greater than in another possible state to which a transition exists. A spontaneous transition is always prevented by an energy barrier, to overcome which the microparticle must receive a certain amount of energy from the outside - excitation energy. The exoenergetic reaction consists in the fact that in the transformation following excitation, more energy is released than is required to excite the process. There are two ways to overcome the energy barrier: either due to the kinetic energy of colliding particles, or due to the binding energy of the joining particle.

If we keep in mind the macroscopic scale of energy release, then all or initially at least some fraction of particles of the substance must have the kinetic energy necessary to excite reactions. This is achievable only by increasing the temperature of the medium to a value at which the energy of thermal motion approaches the energy threshold limiting the course of the process. In the case of molecular transformations, that is, chemical reactions, such an increase is usually hundreds of kelvins, but in the case of nuclear reactions it is at least 10 7 due to the very high height of the Coulomb barriers of colliding nuclei. Thermal excitation of nuclear reactions is carried out in practice only during the synthesis of the lightest nuclei, in which the Coulomb barriers are minimal (thermonuclear fusion).

Excitation by joining particles does not require large kinetic energy, and, therefore, does not depend on the temperature of the medium, since it occurs due to unused bonds inherent in the attractive forces of particles. But to excite reactions, the particles themselves are necessary. And if we again mean not a separate act of reaction, but the production of energy on a macroscopic scale, then this is possible only when a chain reaction occurs. The latter occurs when the particles that excite the reaction reappear as products of an exoenergetic reaction.

Design

Any nuclear reactor consists of the following parts:

• Core with nuclear fuel and moderator;
• Neutron reflector surrounding the core;
• Chain reaction control system, including emergency protection;
• Radiation protection;
• Remote control system.

Physical principles of operation

See also the main articles:

The current state of a nuclear reactor can be characterized by the effective neutron multiplication factor k or reactivity ρ , which are related by the following relation:

The following values ​​are typical for these quantities:

• k> 1 - the chain reaction increases over time, the reactor is in supercritical state, its reactivity ρ > 0;
• k < 1 - реакция затухает, реактор - subcritical, ρ < 0;
• k = 1, ρ = 0 - the number of nuclear fissions is constant, the reactor is in a stable critical condition.

Criticality condition for a nuclear reactor:

Reversing the multiplication factor to unity is achieved by balancing the multiplication of neutrons with their losses. There are actually two reasons for the losses: capture without fission and leakage of neutrons outside the breeding medium.

It is obvious that k< k 0 , поскольку в конечном объёме вследствие утечки потери нейтронов обязательно больше, чем в бесконечном. Поэтому, если в веществе данного состава k 0 < 1, то цепная самоподдерживающаяся реакция невозможна как в бесконечном, так и в любом конечном объёме. Таким образом, k 0 определяет принципиальную способность среды размножать нейтроны.

k 0 for thermal reactors can be determined by the so-called “formula of 4 factors”:

• η is the neutron yield for two absorptions.

The volumes of modern power reactors can reach hundreds of m³ and are determined mainly not by criticality conditions, but by heat removal capabilities.

Critical volume nuclear reactor - the volume of the reactor core in a critical state. Critical mass- the mass of the fissile material of the reactor, which is in a critical state.

Reactors in which the fuel is aqueous solutions of salts of pure fissile isotopes with a water neutron reflector have the lowest critical mass. For 235 U this mass is 0.8 kg, for 239 Pu - 0.5 kg. It is widely known, however, that the critical mass for the LOPO reactor (the world's first enriched uranium reactor), which had a beryllium oxide reflector, was 0.565 kg, despite the fact that the degree of enrichment for isotope 235 was only slightly more than 14%. Theoretically, it has the smallest critical mass, for which this value is only 10 g.

In order to reduce neutron leakage, the core is given a spherical or close to spherical shape, for example, a short cylinder or cube, since these figures have the smallest surface area to volume ratio.

Despite the fact that the value (e - 1) is usually small, the role of fast neutron breeding is quite large, since for large nuclear reactors (K ∞ - 1)<< 1. Без этого процесса было бы невозможным создание первых графитовых реакторов на естественном уране.

To start a chain reaction, neutrons produced during the spontaneous fission of uranium nuclei are usually sufficient. It is also possible to use an external source of neutrons to start the reactor, for example, a mixture of and, or other substances.

Iodine pit

Iodine pit is a state of a nuclear reactor after it is turned off, characterized by the accumulation of the short-lived isotope xenon. This process leads to the temporary appearance of significant negative reactivity, which, in turn, makes it impossible to bring the reactor to its design capacity within a certain period (about 1-2 days).

Classification

By purpose

According to the nature of their use, nuclear reactors are divided into:

• Power reactors designed to produce electrical and thermal energy used in the energy sector, as well as for desalination of sea water (desalination reactors are also classified as industrial). Such reactors are mainly used in nuclear power plants. The thermal power of modern power reactors reaches 5 GW. A separate group includes:
  • Transport reactors, designed to supply energy to vehicle engines. The widest groups of applications are marine transport reactors used on submarines and various surface vessels, as well as reactors used in space technology.
• Experimental reactors, intended for the study of various physical quantities, the value of which is necessary for the design and operation of nuclear reactors; The power of such reactors does not exceed several kW.
• Research reactors, in which fluxes of neutrons and gamma quanta created in the core are used for research in the field of nuclear physics, solid state physics, radiation chemistry, biology, for testing materials intended to operate in intense neutron fluxes (including parts nuclear reactors) for the production of isotopes. The power of research reactors does not exceed 100 MW. The released energy is usually not used.
• Industrial (weapons, isotope) reactors, used to produce isotopes used in various fields. Most widely used to produce nuclear weapons materials, such as 239 Pu. Also classified as industrial are reactors used for desalination of sea water.

Often reactors are used to solve two or more different problems, in which case they are called multi-purpose. For example, some power reactors, especially in the early days of nuclear power, were designed primarily for experimentation. Fast neutron reactors can simultaneously produce energy and produce isotopes. Industrial reactors, in addition to their main task, often generate electrical and thermal energy.

According to the neutron spectrum

• Thermal (slow) neutron reactor (“thermal reactor”)
• Fast neutron reactor ("fast reactor")

By fuel placement

• Heterogeneous reactors, where fuel is placed discretely in the core in the form of blocks, between which there is a moderator;
• Homogeneous reactors, where the fuel and moderator are a homogeneous mixture (homogeneous system).

In a heterogeneous reactor, the fuel and moderator can be spatially separated, in particular, in a cavity reactor, the moderator-reflector surrounds a cavity with fuel that does not contain a moderator. From a nuclear physical point of view, the criterion for homogeneity/heterogeneity is not the design, but the placement of fuel blocks at a distance exceeding the neutron moderation length in a given moderator. Thus, reactors with the so-called “close lattice” are designed as homogeneous, although in them the fuel is usually separated from the moderator.

Nuclear fuel blocks in a heterogeneous reactor are called fuel assemblies (FA), which are located in the core at the nodes of a regular lattice, forming cells.

By fuel type

• uranium isotopes 235, 238, 233 (235 U, 238 U, 233 U)
• plutonium isotope 239 (239 Pu), also isotopes 239-242 Pu in the form of a mixture with 238 U (MOX fuel)
• thorium isotope 232 (232 Th) (via conversion to 233 U)

By degree of enrichment:

• natural uranium
• weakly enriched uranium
• highly enriched uranium

By chemical composition:

• metal U
• UC (uranium carbide), etc.

By type of coolant

• Gas, (see Graphite-gas reactor)
• D 2 O (heavy water, see Heavy water nuclear reactor, CANDU)

By type of moderator

• C (graphite, see Graphite-gas reactor, Graphite-water reactor)
• H2O (water, see Light water reactor, Water-cooled reactor, VVER)
• D 2 O (heavy water, see Heavy water nuclear reactor, CANDU)
• Metal hydrides
• Without moderator (see Fast reactor)

By design

By steam generation method

• Reactor with external steam generator (See Water-water reactor, VVER)

IAEA classification

• PWR (pressurized water reactors) - water-water reactor (pressurized water reactor);
• BWR (boiling water reactor) - boiling water reactor;
• FBR (fast breeder reactor) - fast breeder reactor;
• GCR (gas-cooled reactor) - gas-cooled reactor;
• LWGR (light water graphite reactor) - graphite-water reactor
• PHWR (pressurized heavy water reactor) - heavy water reactor

The most common in the world are pressurized water (about 62%) and boiling water (20%) reactors.

Reactor materials

The materials from which reactors are built operate at high temperatures in a field of neutrons, γ quanta and fission fragments. Therefore, not all materials used in other branches of technology are suitable for reactor construction. When choosing reactor materials, their radiation resistance, chemical inertness, absorption cross section and other properties are taken into account.

The radiation instability of materials has less effect at high temperatures. The mobility of atoms becomes so great that the probability of the return of atoms knocked out of the crystal lattice to their place or the recombination of hydrogen and oxygen into a water molecule increases markedly. Thus, the radiolysis of water is insignificant in energy non-boiling reactors (for example, VVER), while in powerful research reactors a significant amount of explosive mixture is released. Reactors have special systems for burning it.

Reactor materials are in contact with each other (fuel shell with coolant and nuclear fuel, fuel cassettes with coolant and moderator, etc.). Naturally, the contacting materials must be chemically inert (compatible). An example of incompatibility is uranium and hot water entering into a chemical reaction.

For most materials, the strength properties deteriorate sharply with increasing temperature. In power reactors, structural materials operate at high temperatures. This limits the choice of construction materials, especially for those parts of the power reactor that must withstand high pressure.

Burnout and reproduction of nuclear fuel

During the operation of a nuclear reactor, due to the accumulation of fission fragments in the fuel, its isotopic and chemical composition changes, and transuranic elements, mainly isotopes, are formed. The effect of fission fragments on the reactivity of a nuclear reactor is called poisoning(for radioactive fragments) and slagging(for stable isotopes).

The main reason for reactor poisoning is , which has the largest neutron absorption cross section (2.6·10 6 barn). Half-life of 135 Xe T 1/2 = 9.2 hours; The yield during division is 6-7%. The bulk of 135 Xe is formed as a result of the decay ( T 1/2 = 6.8 hours). In case of poisoning, Keff changes by 1-3%. The large absorption cross section of 135 Xe and the presence of the intermediate isotope 135 I lead to two important phenomena:

1. To an increase in the concentration of 135 Xe and, consequently, to a decrease in the reactivity of the reactor after it is stopped or the power is reduced (“iodine pit”), which makes short-term stops and fluctuations in output power impossible. This effect is overcome by introducing a reactivity reserve in regulatory bodies. The depth and duration of the iodine well depend on the neutron flux Ф: at Ф = 5·10 18 neutron/(cm²·sec) the duration of the iodine well is ˜ 30 hours, and the depth is 2 times greater than the stationary change in Keff caused by 135 Xe poisoning.
2. Due to poisoning, spatiotemporal fluctuations in the neutron flux F, and, consequently, in the reactor power, can occur. These oscillations occur at Ф > 10 18 neutrons/(cm²·sec) and large reactor sizes. Oscillation periods ˜ 10 hours.

Nuclear fission produces a large number of stable fragments, which differ in absorption cross sections compared to the absorption cross section of the fissile isotope. The concentration of fragments with a large absorption cross section reaches saturation within the first few days of reactor operation. These are mainly fuel rods of different “ages”.

In the case of a complete fuel change, the reactor has excess reactivity that needs to be compensated, while in the second case compensation is required only when the reactor is first started. Continuous overloading makes it possible to increase the burnup depth, since the reactivity of the reactor is determined by the average concentrations of fissile isotopes.

The mass of loaded fuel exceeds the mass of unloaded fuel due to the “weight” of the released energy. After the reactor is shut down, first mainly due to fission by delayed neutrons, and then, after 1-2 minutes, due to β- and γ-radiation of fission fragments and transuranium elements, the release of energy in the fuel continues. If the reactor worked long enough before stopping, then 2 minutes after stopping, the energy release is about 3%, after 1 hour - 1%, after a day - 0.4%, after a year - 0.05% of the initial power.

The ratio of the number of fissile Pu isotopes formed in a nuclear reactor to the amount of burnt 235 U is called conversion rate K K . The value of K K increases with decreasing enrichment and burnup. For a heavy water reactor using natural uranium, with a burnup of 10 GW day/t K K = 0.55, and with small burnups (in this case K K is called initial plutonium coefficient) K K = 0.8. If a nuclear reactor burns and produces the same isotopes (breeder reactor), then the ratio of the reproduction rate to the burnup rate is called reproduction rate K V. In nuclear reactors using thermal neutrons K V< 1, а для реакторов на быстрых нейтронах К В может достигать 1,4-1,5. Рост К В для реакторов на быстрых нейтронах объясняется главным образом тем, что, особенно в случае 239 Pu, для быстрых нейтронов g grows and A falls.

Nuclear reactor control

Control of a nuclear reactor is possible only due to the fact that during fission, some of the neutrons fly out of the fragments with a delay, which can range from several milliseconds to several minutes.

To control the reactor, absorber rods are used, introduced into the core, made of materials that strongly absorb neutrons (mainly, and some others) and/or a solution of boric acid, added to the coolant in a certain concentration (boron control). The movement of the rods is controlled by special mechanisms, drives, operating according to signals from the operator or equipment for automatic control of the neutron flux.

In case of various emergency situations, each reactor is provided with an emergency termination of the chain reaction, carried out by dropping all absorbing rods into the core - an emergency protection system.

Residual Heat

An important issue directly related to nuclear safety is decay heat. This is a specific feature of nuclear fuel, which consists in the fact that, after the cessation of the fission chain reaction and the thermal inertia usual for any energy source, the release of heat in the reactor continues for a long time, which creates a number of technically complex problems.

Residual heat is a consequence of the β- and γ-decay of fission products that accumulated in the fuel during the operation of the reactor. Fission product nuclei, due to decay, transform into a more stable or completely stable state with the release of significant energy.

Although the decay heat release rate quickly decreases to values ​​small compared to steady-state values, in high-power power reactors it is significant in absolute terms. For this reason, residual heat generation entails the need for a long period of time to ensure heat removal from the reactor core after it is shut down. This task requires the design of the reactor installation to have cooling systems with a reliable power supply, and also necessitates long-term (3-4 years) storage of spent nuclear fuel in storage facilities with a special temperature regime - cooling pools, which are usually located in close proximity to the reactor.

see also

• List of nuclear reactors designed and built in the Soviet Union

Literature

• Levin V. E. Nuclear physics and nuclear reactors. 4th ed. - M.: Atomizdat, 1979.
• Shukolyukov A. Yu. “Uranium. Natural nuclear reactor." “Chemistry and Life” No. 6, 1980, p. 20-24

Notes

1. "ZEEP - Canada's First Nuclear Reactor", Canada Science and Technology Museum.
2. Greshilov A. A., Egupov N. D., Matushchenko A. M. Nuclear shield. - M.: Logos, 2008. - 438 p. -

I. Design of a nuclear reactor

A nuclear reactor consists of the following five main elements:

1) nuclear fuel;

2) neutron moderator;

3) regulatory systems;

4) cooling systems;

5) protective screen.

1. Nuclear fuel.

Nuclear fuel is a source of energy. There are currently three known types of fissile materials:

a) uranium 235, which makes up 0.7%, or 1/140 of natural uranium;

6) plutonium 239, which is formed in some reactors based on uranium 238, which makes up almost the entire mass of natural uranium (99.3%, or 139/140 parts).

Capturing neutrons, uranium 238 nuclei turn into neptunium nuclei - the 93rd element of the Mendeleev periodic system; the latter, in turn, turn into plutonium nuclei - the 94th element of the periodic table. Plutonium is easily extracted from irradiated uranium by chemical means and can be used as nuclear fuel;

c) uranium 233, which is an artificial isotope of uranium obtained from thorium.

Unlike uranium 235, which is found in natural uranium, plutonium 239 and uranium 233 are obtained only artificially. That's why they are called secondary nuclear fuel; The source of such fuel is uranium 238 and thorium 232.

Thus, among all the types of nuclear fuel listed above, uranium is the main one. This explains the enormous scope that searches and exploration of uranium deposits are taking in all countries.

The energy released in a nuclear reactor is sometimes compared with that released during a chemical combustion reaction. However, there is a fundamental difference between them.

The amount of heat obtained during the fission of uranium is immeasurably greater than the amount of heat obtained during combustion, for example, of coal: 1 kg of uranium 235, equal in volume to a pack of cigarettes, could theoretically provide as much energy as 2600 tons of coal.

However, these energy opportunities are not fully exploited, since not all uranium 235 can be separated from natural uranium. As a result, 1 kg of uranium, depending on the degree of its enrichment with uranium 235, is currently equivalent to approximately 10 tons of coal. But it should be taken into account that the use of nuclear fuel facilitates transportation and, therefore, significantly reduces the cost of fuel. British experts have calculated that by enriching uranium they will be able to increase the heat produced in reactors by 10 times, which would equate 1 ton of uranium to 100 thousand tons of coal.

The second difference between the process of nuclear fission, which occurs with the release of heat, and chemical combustion is that the combustion reaction requires oxygen, while to initiate a chain reaction only a few neutrons and a certain mass of nuclear fuel is required, equal to the critical mass, which we define already given in the section on the atomic bomb.

And finally, the invisible process of nuclear fission is accompanied by the emission of extremely harmful radiation, from which protection must be provided.

2. Neutron moderator.

In order to avoid the spread of fission products in the reactor, nuclear fuel must be placed in special shells. To make such shells, you can use aluminum (the coolant temperature should not exceed 200°), or even better, beryllium or zirconium - new metals, the production of which in their pure form is fraught with great difficulties.

The neutrons produced during nuclear fission (on average 2–3 neutrons during the fission of one nucleus of a heavy element) have a certain energy. In order for the probability of neutrons to split other nuclei to be greatest, without which the reaction will not be self-sustaining, it is necessary that these neutrons lose part of their speed. This is achieved by placing a moderator in the reactor, in which fast neutrons are converted into slow ones as a result of numerous successive collisions. Since the substance used as a moderator must have nuclei with a mass approximately equal to the mass of neutrons, that is, the nuclei of light elements, heavy water was used as a moderator from the very beginning (D 2 0, where D is deuterium, which replaced light hydrogen in ordinary water N 2 0). However, now they are trying to use graphite more and more - it is cheaper and gives almost the same effect.

A ton of heavy water purchased in Sweden costs 70–80 million francs. At the Geneva Conference on the Peaceful Uses of Atomic Energy, the Americans announced that they would soon be able to sell heavy water at a price of 22 million francs per ton.

A ton of graphite costs 400 thousand francs, and a ton of beryllium oxide costs 20 million francs.

The substance used as a moderator must be pure to avoid loss of neutrons as they pass through the moderator. At the end of the run, the neutrons have an average speed of about 2200 m/sec, while their initial speed was about 20 thousand km/sec. In reactors, the release of heat occurs gradually and can be controlled, unlike an atomic bomb, where it occurs instantly and takes on the character of an explosion.

Some types of fast reactors do not require a moderator.

3. Regulatory system.

A person should be able to cause, regulate and stop a nuclear reaction at will. This is achieved using control rods made of boron steel or cadmium - materials that have the ability to absorb neutrons. Depending on the depth to which the control rods are lowered into the reactor, the number of neutrons in the core increases or decreases, which ultimately makes it possible to regulate the process. The control rods are controlled automatically using servomechanisms; Some of these rods can instantly fall into the core in case of danger.

At first there were concerns that a reactor explosion would cause the same damage as an atomic bomb. In order to prove that a reactor explosion occurs only under conditions different from normal ones and does not pose a serious danger to the population living in the vicinity of the nuclear plant, the Americans deliberately blew up one so-called “boiling” reactor. Indeed, there was an explosion that we can characterize as “classical,” that is, non-nuclear; this once again proves that nuclear reactors can be built near populated areas without any particular danger to the latter.

4. Cooling system.

During nuclear fission, a certain energy is released, which is transferred to the decay products and the resulting neutrons. This energy, as a result of numerous collisions of neutrons, is converted into thermal energy, therefore, in order to prevent rapid failure of the reactor, heat must be removed. In reactors designed to produce radioactive isotopes, this heat is not used, but in reactors designed to produce energy, it becomes, on the contrary, the main product. Cooling can be carried out using gas or water, which circulates in the reactor under pressure through special tubes and is then cooled in a heat exchanger. The heat released can be used to heat the steam that rotates a turbine connected to the generator; such a device would be a nuclear power plant.

5. Protective screen.

In order to avoid the harmful effects of neutrons that can fly outside the reactor, and to protect yourself from the gamma radiation emitted during the reaction, reliable protection is necessary. Scientists have calculated that a reactor with a power of 100 thousand kW emits such an amount of radioactive radiation that a person located at a distance of 100 m from it would receive it in 2 minutes. lethal dose. To ensure the protection of personnel servicing the reactor, two-meter walls are built from special concrete with lead slabs.

The first reactor was built in December 1942 by the Italian Fermi. By the end of 1955, there were about 50 nuclear reactors in the world (USA - 2 1, England - 4, Canada - 2, France - 2). It should be added that by the beginning of 1956, about 50 more reactors were designed for research and industrial purposes (USA - 23, France - 4, England - 3, Canada - 1).

The types of these reactors are very diverse, ranging from slow neutron reactors with graphite moderators and natural uranium as fuel to fast neutron reactors using uranium enriched with plutonium or uranium 233, produced artificially from thorium, as fuel.

In addition to these two opposing types, there is a whole series of reactors that differ from each other either in the composition of the nuclear fuel, or in the type of moderator, or in the coolant.

It is very important to note that, although the theoretical side of the issue is now well studied by specialists in all countries, in the practical field different countries have not yet reached the same level. The USA and Russia are ahead of other countries. It can be argued that the future of nuclear energy will depend mainly on the progress of technology.

author Ivanov Igor Pierovich

The structure of the LHC collider Now a few pictures. A collider is an accelerator of colliding particles. There, particles accelerate along two rings and collide with each other. This is the largest experimental installation in the world, because the length of this ring - the tunnel -

From the book The Newest Book of Facts. Volume 3 [Physics, chemistry and technology. History and archaeology. Miscellaneous] author Kondrashov Anatoly Pavlovich

From the book The Atomic Problem by Ran Philip

From book 5b. Electricity and magnetism author Feynman Richard Phillips

From the author's book

Chapter VIII Principle of operation and capabilities of a nuclear reactor I. Design of a nuclear reactor A nuclear reactor consists of the following five main elements: 1) nuclear fuel; 2) neutron moderator; 3) control system; 4) cooling system; 5) protective

From the author's book

Chapter 11 INTERNAL STRUCTURE OF DIELECTRICS §1. Molecular dipoles§2. Electronic polarization §3. Polar molecules; orientation polarization§4. Electric fields in dielectric voids§5. Dielectric constant of liquids; Clausius-Mossotti formula§6.

The importance of nuclear energy in the modern world

Nuclear energy has made huge strides over the past few decades, becoming one of the most important sources of electricity for many countries. At the same time, it should be remembered that behind the development of this sector of the national economy are the enormous efforts of tens of thousands of scientists, engineers and ordinary workers, doing everything to ensure that the “peaceful atom” does not turn into a real threat to millions of people. The real core of any nuclear power plant is the nuclear reactor.

History of the creation of a nuclear reactor

The first such device was built at the height of the Second World War in the USA by the famous scientist and engineer E. Fermi. Because of its unusual appearance, which resembled a stack of graphite blocks stacked on top of each other, this nuclear reactor was called the Chicago Stack. It is worth noting that this device operated on uranium, which was placed just between the blocks.

Creation of a nuclear reactor in the Soviet Union

In our country, increased attention was also paid to nuclear issues. Despite the fact that the main efforts of scientists were concentrated on the military use of the atom, they actively used the results obtained for peaceful purposes. The first nuclear reactor, codenamed F-1, was built by a group of scientists led by the famous physicist I. Kurchatov at the end of December 1946. Its significant drawback was the absence of any cooling system, so the power of energy it released was extremely insignificant. At the same time, Soviet researchers completed the work they had begun, which resulted in the opening just eight years later of the world's first nuclear power plant in the city of Obninsk.

Operating principle of the reactor

A nuclear reactor is an extremely complex and dangerous technical device. Its principle of operation is based on the fact that during the decay of uranium, several neutrons are released, which, in turn, knock out elementary particles from neighboring uranium atoms. This chain reaction releases a significant amount of energy in the form of heat and gamma rays. At the same time, one should take into account the fact that if this reaction is not controlled in any way, then the fission of uranium atoms in the shortest possible time can lead to a powerful explosion with undesirable consequences.

In order for the reaction to proceed within strictly defined limits, the design of a nuclear reactor is of great importance. Currently, each such structure is a kind of boiler through which coolant flows. Water is usually used in this capacity, but there are nuclear power plants that use liquid graphite or heavy water. It is impossible to imagine a modern nuclear reactor without hundreds of special hexagonal cassettes. They contain fuel-generating elements, through the channels of which coolants flow. This cassette is coated with a special layer that is capable of reflecting neutrons and thereby slowing down the chain reaction

Nuclear reactor and its protection

It has several levels of protection. In addition to the body itself, it is covered with special thermal insulation and biological protection on top. From an engineering point of view, this structure is a powerful reinforced concrete bunker, the doors to which are closed as tightly as possible.

Also, if necessary, quickly cool the reactor, they are used a bucket of water And ice.

Element	Heat capacity
	Cooling rod 10k(eng. 10k Coolant Cell)
	10 000
	Cooling rod 30k(eng. 30K Coolant Cell)
	30 000
	Cooling rod 60k(eng. 60K Coolant Cell)
	60 000
	Red capacitor(eng. RSH-Condenser)
	19 999
	By placing an overheated capacitor in a crafting grid along with redstone dust, you can replenish its heat reserve by 10,000 eT. Thus, two pieces of dust are needed to completely restore the capacitor.
	Lapis lazuli capacitor(eng. LZH-Condenser)
	99 999
	It is replenished not only with redstone (5000 eT), but also with lapis lazuli for 40,000 eT.

Nuclear reactor cooling (up to version 1.106)

• The cooling rod can store 10,000 eT and cools by 1 eT every second.
• The reactor cladding also stores 10,000 eT, cooling every second with a 10% chance of 1 eT (on average 0.1 eT). Through thermoplates, fuel elements and heat spreaders can distribute heat to a larger number of cooling elements.
• The heat spreader stores 10,000 eT, and also balances the heat level of nearby elements, but redistributing no more than 6 eT/s to each. It also redistributes heat to the body, up to 25 eT/s.
• Passive cooling.

• Each block of air surrounding the reactor in a 3x3x3 area around the nuclear reactor cools the vessel by 0.25 eT/s, and each block of water cools by 1 eT/s.
• In addition, the reactor itself is cooled by 1 eT/s, thanks to the internal ventilation system.
• Each additional reactor chamber is also ventilated and cools the housing by another 2 eT/s.
• But if there are lava blocks (sources or flows) in the 3x3x3 zone, then they reduce the cooling of the hull by 3 eT/s. And a burning fire in the same area reduces cooling by 0.5 eT/s.

If the total cooling is negative, then the cooling will be zero. That is, the reactor vessel will not be cooled. You can calculate that the maximum passive cooling is: 1+6*2+20*1 = 33 eT/s.

• Emergency cooling (up to version 1.106).

In addition to conventional cooling systems, there are “emergency” coolers that can be used for emergency cooling of a reactor (even with high heat generation):

• A bucket of water placed in the core cools the nuclear reactor vessel by 250 eT if it is heated by at least 4,000 eT.
• Ice cools the body by 300 eT if it is heated by at least 300 eT.

Classification of nuclear reactors

Nuclear reactors have their own classification: MK1, MK2, MK3, MK4 and MK5. Types are determined by the release of heat and energy, as well as some other aspects. MK1 is the safest, but produces the least amount of energy. The MK5 produces the most energy with the greatest chance of explosion.

MK1

The safest type of reactor, which does not heat up at all, and at the same time produces the least amount of energy. Divided into two subtypes: MK1A - one that meets class conditions regardless of the environment and MK1B - one that requires passive cooling to comply with class 1 standards.

MK2

The most optimal type of reactor, which, when operating at full power, does not heat up by more than 8500 eT per cycle (the time during which the fuel rod manages to completely discharge or 10,000 seconds). Thus, this is the optimal heat/energy compromise. For these types of reactors there is also a separate classification MK2x, where x is the number of cycles that the reactor will operate without critical overheating. The number can be from 1 (one cycle) to E (16 cycles or more). MK2-E is the standard among all nuclear reactors, since it is practically eternal. (That is, before the end of the 16th cycle the reactor will have time to cool to 0 eT)

MK3

A reactor that can run at least 1/10 of a full cycle without evaporating water/melting blocks. More powerful than MK1 and MK2, but requires additional supervision, because after some time the temperature can reach a critical level.

MK4

A reactor that can operate at least 1/10 of a full cycle without explosions. The most powerful of the operational types of Nuclear Reactors, which requires the most attention. Requires constant supervision. For the first time it emits approximately 200,000 to 1,000,000 eE.

MK5

Class 5 nuclear reactors are inoperable, mainly used to prove the fact that they explode. Although it is possible to make a functional reactor of this class, there is no point in doing so.

Additional classification

Even though reactors already have as many as 5 classes, reactors are sometimes divided into several more minor, but important subclasses of cooling type, efficiency and performance.

Cooling

-SUC(single use coolants - one-time use of cooling elements)

• Before version 1.106, this marking indicated emergency cooling of the reactor (using buckets of water or ice). Typically, such reactors are rarely used or not used at all due to the fact that the reactor may not operate for very long without supervision. This was usually used for the Mk3 or Mk4.
• After version 1.106 thermal capacitors appeared. The -SUC subclass now denotes the presence of thermal capacitors in the circuit. Their heat capacity can be quickly restored, but this will require spending red dust or lapis lazuli.

Efficiency

Efficiency is the average number of pulses produced by the fuel rods. Roughly speaking, this is the number of millions of energy obtained as a result of the operation of the reactor, divided by the number of fuel rods. But in the case of enrichment circuits, part of the pulses is spent on enrichment, and in this case the efficiency does not quite correspond to the energy received and will be higher.

Twin and quadruple fuel rods have higher basic efficiency compared to single ones. By themselves, single fuel elements produce one pulse, double ones - two, quadruple ones - three. If one of the four neighboring cells contains another fuel element, a depleted fuel element or a neutron reflector, then the number of pulses increases by one, that is, by a maximum of 4 more. From the above it becomes clear that the efficiency cannot be less than 1 or more than 7.

Marking	Meaning efficiency
E.E.	=1
ED	>1 and<2
E.C.	≥2 and<3
E.B.	≥3 and<4
E.A.	≥4 and<5
EA+	≥5 and<6
EA++	≥6 and<7
EA*	=7

Other subclasses

You may sometimes see additional letters, abbreviations, or other symbols on reactor diagrams. Although these symbols are used (for example, the subclass -SUC was not officially registered before), they are not very popular. Therefore, you can call your reactor even Mk9000-2 EA^ dzhigurda, but this type of reactor simply will not be understood and will be considered a joke.

Construction of the reactor

We all know that the reactor heats up and an explosion can suddenly occur. And we have to turn it off and on. The following describes how you can protect your home, as well as how to make the most of a reactor that will never explode. In this case, you should already have 6 reactor chambers installed.

View of the reactor with chambers. Nuclear reactor inside.

1. Cover the reactor with reinforced stone (5x5x5)
2. Perform passive cooling, that is, fill the entire reactor with water. Fill it from the top as the water will flow down. Using this scheme, the reactor will be cooled by 33 eT per second.
3. Make the maximum amount of energy generated with cooling rods, etc. Be careful, because if even 1 heat spreader is placed incorrectly, disaster can occur! (the diagram is shown for versions up to 1.106)
4. To prevent our MFE from exploding from high voltage, we install a transformer as in the picture.

Mk-V EB reactor

Many people know that updates bring changes. One of these updates included new fuel rods - dual and quadruple. The diagram above does not fit these fuel rods. Below is a detailed description of the manufacture of a rather dangerous but effective reactor. To do this, IndustrialCraft 2 requires Nuclear Control. This reactor filled the MFSU and MFE in approximately 30 minutes of real time. Unfortunately, this is an MK4 class reactor. But it completed its task by heating up to 6500 eT. It is recommended to install 6500 on the temperature sensor and connect an alarm and emergency shutdown system to the sensor. If the alarm screams for more than two minutes, then it is better to turn off the reactor manually. The construction is the same as above. Only the location of the components has been changed.

Output power: 360 EU/t

Total EE: 72,000,000 EE

Generation time: 10 min. 26 sec.

Reload Time: Impossible

Maximum cycles: 6.26% cycle

Total time: Never

The most important thing in such a reactor is not to let it explode!

Mk-II-E-SUC Breeder EA+ reactor with the ability to enrich depleted fuel elements

A fairly effective but expensive type of reactor. It produces 720,000 eT per minute and the capacitors heat up by 27/100, therefore, without cooling the capacitors, the reactor will withstand 3 minute cycles, and the 4th will almost certainly explode it. It is possible to install depleted fuel elements for enrichment. It is recommended to connect the reactor to a timer and enclose the reactor in a “sarcophagus” made of reinforced stone. Due to the high output voltage (600 EU/t), high-voltage wires and a HV transformer are required.

Output power: 600 EU/t

Total eE: 120,000,000 eE

Generation time: Full cycle

Mk-I EB reactor

The elements do not heat up at all, 6 quadruple fuel rods work.

Output power: 360 EU/t

Total EE: 72,000,000 EE

Generation time: Full cycle

Recharge Time: Not Required

Maximum cycles: Infinite number

Total time: 2 hours 46 minutes 40 sec.

Mk-I EA++ reactor

Low-power, but economical in terms of raw materials and cheap to build. Requires neutron reflectors.

Output power: 60 EU/t

Total eE: 12,000,000 eE

Generation time: Full cycle

Recharge Time: Not Required

Maximum cycles: Infinite number

Total time: 2 hours 46 minutes 40 sec.

Reactor Mk-I EA*

Medium power but relatively cheap and extremely efficient. Requires neutron reflectors.

Output power: 140 EU/t

Total EE: 28,000,000 EE

Generation time: Full cycle

Recharge Time: Not Required

Maximum cycles: Infinite number

Total time: 2 hours 46 minutes 40 sec.

Mk-II-E-SUC Breeder EA+ reactor, uranium enrichment

Compact and cheap to build uranium enricher. The safe operation time is 2 minutes 20 seconds, after which it is recommended to repair lapis lazuli capacitors (repairing one - 2 lapis lazuli + 1 redstone), which will require constant monitoring of the reactor. Also, due to uneven enrichment, it is recommended to swap highly enriched rods with weakly enriched ones. At the same time, it can produce 48,000,000 eE per cycle.

Output power: 240 EU/t

Total EE: 48,000,000 EE

Generation time: Full cycle

Recharge Time: Not Required

Maximum cycles: Infinite number

Total time: 2 hours 46 minutes 40 sec.

Mk-I EC reactor

"Room" reactor. It has low power, but it is very cheap and absolutely safe - all supervision of the reactor comes down to replacing the rods, since cooling by ventilation exceeds heat generation by 2 times. It is best to place it close to the MFE/MFSU and configure them to emit a redstone signal when partially charged (Emit if partially filled), so the reactor will automatically fill the energy store and turn off when it is full. To craft all components you will need 292 copper, 102 iron, 24 gold, 8 redstone, 7 rubber, 7 tin, 2 units of light dust and lapis lazuli, as well as 6 units of uranium ore. It produces 16 million eU per cycle.

Output power: 80 EU/t

Total EE: 32,000,000 EE

Generation time: Full cycle

Recharge Time: Not Required

Maximum cycles: Infinite number

Total time: about 5 hours 33 minutes. 00 sec.

Reactor Timer

MK3 and MK4 class reactors do produce a lot of energy in a short time, but they tend to explode unattended. But with the help of a timer, you can make even these capricious reactors work without critical overheating and allow you to go away, for example, to dig up sand for your cactus farm. Here are three examples of timers:

• Timer made from a dispenser, a wooden button and arrows (Fig. 1). A fired arrow is an essence, its lifespan is 1 minute. When connecting a wooden button with an arrow stuck in it to the reactor, it will work for ~ 1 minute. 1.5 sec. It would be best to open access to a wooden button, then it will be possible to urgently stop the reactor. At the same time, the consumption of arrows is reduced, since when the dispenser is connected to another button other than a wooden one, after pressing, the dispenser releases 3 arrows at once due to the multiple signal.
• Wooden pressure plate timer (Fig. 2). The wooden pressure plate reacts if an object falls on it. Dropped items have a “lifespan” of 5 minutes (in SMP there may be deviations due to ping), and if you connect the plate to the reactor, it will work for ~5 minutes. 1 sec. When creating many timers, you can put this timer first in the chain, so as not to install a distributor. Then the entire chain of timers will be triggered by the player throwing an item onto the pressure plate.
• Repeater timer (Fig. 3). A repeater timer can be used to fine-tune the delay of a reactor, but it is very cumbersome and requires a large amount of resources to create even a small delay. The timer itself is a signal support line (10.6). As you can see, it takes up a lot of space, and the signal delay is 1.2 seconds. as many as 7 repeaters are required (21

  Passive cooling (up to version 1.106)

  The base cooling of the reactor itself is 1. Next, the 3x3x3 area around the reactor is checked. Each reactor chamber adds 2 to the cooling. A block with water (source or current) adds 1. A block with lava (source or current) decreases by 3. Blocks with air and fire are counted separately. They add to the cooling (number of air blocks-2×number of fire blocks)/4(if the result of division is not an integer, then the fractional part is discarded). If the total cooling is less than 0, then it is considered equal to 0.
  That is, the reactor vessel cannot heat up due to external factors. In the worst case, it simply will not cool due to passive cooling.

  Temperature

  At high temperatures, the reactor begins to have a negative impact on the environment. This effect depends on the heating coefficient. Heating factor=Current reactor vessel temperature/Maximum temperature, Where Maximum reactor temperature=10000+1000*number of reactor chambers+100*number of thermoplates inside the reactor.
  If the heating coefficient:

  • <0,4 - никаких последствий нет.
  • >=0.4 - there is a chance 1.5×(heating coefficient -0.4) that a random block in the zone will be selected 5x5x5, and if it happens to be a flammable block, such as leaves, some wood block, wool or a bed, then it will burn.
  That is, with a heating coefficient of 0.4 the chances are zero, with a heating coefficient of 0.67 it will be higher than 100%. That is, with a heating coefficient of 0.85 the chance will be 4×(0.85-0.7)=0.6 (60%), and with 0.95 and higher the chance will be 4×(95-70)=1 (100 %). Depending on the block type, the following will happen:
  • if it is a central block (the reactor itself) or a bedrock block, then there will be no effect.
  • stone blocks (including steps and ore), iron blocks (including reactor blocks), lava, earth, clay will be turned into a lava flow.
  • if it is an air block, then there will be an attempt to light a fire in its place (if there are no solid blocks nearby, the fire will not appear).
  • the remaining blocks (including water) will evaporate, and in their place there will also be an attempt to light a fire.
  • >=1 - Explosion! The base explosion power is 10. Each fuel element in the reactor increases the explosion power by 3 units, and each reactor cladding reduces it by one. Also, the explosion power is limited to a maximum of 45 units. In terms of the number of blocks dropped, this explosion is similar to a nuclear bomb; 99% of the blocks after the explosion will be destroyed, and the drop will be only 1%.

  Calculation of heating or low-enriched fuel elements, then the reactor vessel heats up by 1 eT.

• If this is a bucket of water, and the temperature of the reactor vessel is more than 4000 eT, then the vessel is cooled by 250 eT, and the bucket of water is replaced with an empty bucket.
• If this is a lava bucket, then the reactor vessel is heated by 2000 eT, and the lava bucket is replaced with an empty bucket.
• If this is a block of ice, and the temperature of the case is more than 300 eT, then the case is cooled by 300 eT, and the amount of ice is reduced by 1. That is, the entire stack of ice will not evaporate at once.
• If this is a heat spreader, then the following calculation is carried out:
  • 4 adjacent cells are checked, in the following order: left, right, top and bottom.

If they have a cooling capsule or reactor casing, then the heat balance is calculated. Balance=(temperature of the heat spreader - temperature of the adjacent element)/2

1. If the balance is greater than 6, it is equal to 6.
2. If the adjacent element is a cooling capsule, then it heats up to the value of the calculated balance.
3. If this is the reactor cladding, then an additional calculation of heat transfer is performed.

• If there are no cooling capsules near this plate, then the plate will heat up to the value of the calculated balance (heat from the heat spreader does not flow to other elements through the thermal plate).
• If there are cooling capsules, then it is checked whether the heat balance is divisible by their number without a remainder. If it does not divide, then the heat balance increases by 1 eT, and the plate is cooled by 1 eT until it divides completely. But if the reactor cladding has cooled down and the balance is not divided completely, then it heats up, and the balance decreases until it begins to divide completely.
• And, accordingly, these elements are heated to a temperature equal to Balance/quantity.

1. It is taken modulo, and if it is greater than 6, then it is equal to 6.
2. The heat spreader heats up to the balance value.
3. The adjacent element is cooled by the balance value.

• The heat balance between the heat spreader and the housing is calculated.

Balance=(heat spreader temperature-case temperature+1)/2 (if the result of division is not an integer, then the fractional part is discarded)

• If the balance is positive, then:

1. If the balance is more than 25, it is equal to 25.
2. The heat spreader is cooled by the calculated balance value.
3. The reactor vessel is heated to the calculated balance value.

• If the balance is negative, then:

1. It is taken modulo and if it turns out to be more than 25, then it is equal to 25.
2. The heat spreader heats up to the calculated balance value.
3. The reactor vessel is cooled to the calculated balance value.

• If this is a fuel rod, and the reactor is not drowned out by the red dust signal, then the following calculations are carried out:

The number of pulses generating energy for a given rod is counted. Number of pulses=1+number of adjacent uranium rods. Neighboring ones are those that are in the slots on the right, left, top and bottom. The amount of energy generated by the rod is calculated. Amount of energy(eE/t)=10×Number of pulses. eE/t - unit of energy per cycle (1/20th of a second) If there is a depleted fuel element next to the uranium rod, then the number of pulses increases by their number. That is Number of pulses=1+number of adjacent uranium rods+number of adjacent depleted fuel rods. These neighboring depleted fuel elements are also checked, and with some probability they are enriched by two units. Moreover, the chance of enrichment depends on the temperature of the case and if the temperature:

• less than 3000 - chance 1/8 (12.5%);
• from 3000 and less than 6000 - 1/4 (25%);
• from 6000 and less than 9000 - 1/2 (50%);
• 9000 or higher - 1 (100%).

When a depleted fuel element reaches an enrichment value of 10,000 units, it turns into a low-enriched fuel element. Further for each pulse heat generation is calculated. That is, the calculation is performed as many times as there are impulses. The number of cooling elements (cooling capsules, thermal plates and heat spreaders) next to the uranium rod is counted. If their number is equal:

• 0? the reactor vessel heats up by 10 eT.
• 1: The cooling element heats up by 10 eT.
• 2: the cooling elements heat up by 4 eT each.
• 3: each is heated by 2 eT.
• 4: each one is heated by 1 eT.

Moreover, if there are thermal plates there, then they will also redistribute energy. But unlike the first case, the plates next to the uranium rod can distribute heat to both the cooling capsules and the following thermal plates. And the following thermal plates can distribute the heat further only to the cooling rods. TVEL reduces its durability by 1 (initially it is 10000), and if it reaches 0, then it is destroyed. Additionally, with a 1/3 chance when destroyed, it will leave behind an exhausted fuel rod.

Calculation example

There are programs that calculate these circuits. For more reliable calculations and a better understanding of the process, it is worth using them.

Let's take for example this scheme with three uranium rods.

The numbers indicate the order of calculation of the elements in this scheme, and we will use the same numbers to denote the elements so as not to get confused.

For example, let's calculate the heat distribution in the first and second seconds. We will assume that at first there is no heating of the elements, passive cooling is maximum (33 eT), and we will not take into account the cooling of the thermoplates.

First step.

• The reactor vessel temperature is 0 eT.
• 1 - The reactor casing (RP) is not yet heated.
• 2 - The cooling capsule (OxC) is not yet heated, and will no longer cool at this step (0 eT).
• 3 - TVEL will allocate 8 eT (2 cycles of 4 eT each) to the 1st TP (0 eT), which will heat it to 8 eT, and to the 2nd OxC (0 eT), which will heat it to 8 eT.
• 4 - OxC is not yet heated, and there will be no cooling at this step (0 eT).
• 5 - The heat spreader (HR), not yet heated, will balance the temperature with 2m OxC (8 eT). It will cool it down to 4 eT and heat up to 4 eT.

Next, the 5th TP (4 eT) will balance the temperature at the 10th OxC (0 eT). It will heat it up to 2 eT, and it will cool down to 2 eT. Next, the 5th TP (2 eT) will balance the body temperature (0 eT), giving it 1 eT. The case will heat up to 1 eT, and the TP will cool to 1 eT.

• 6 - TVEL will allocate 12 eT (3 cycles of 4 eT each) to the 5th TP (1 eT), which will heat it to 13 eT, and to the 7th TP (0 eT), which will heat it to 12 eT.
• 7 - TP is already heated to 12 eT and can cool down with a 10% chance, but we do not take into account the chance of cooling here.
• 8 - TP (0 eT) will balance the temperature of the 7th TP (12 eT), and take 6 eT from it. The 7th TP will cool to 6 eT, and the 8th TP will heat up to 6 eT.

Next, the 8th TP (6 eT) will balance the temperature at the 9th OxC (0 eT). As a result, it will heat it to 3 eT, and itself will cool to 3 eT. Next, the 8th TP (3 eT) will balance the temperature at the 4th OxC (0 eT). As a result, it will heat it to 1 eT, and itself will cool to 2 eT. Next, the 8th TP (2 eT) will balance the temperature at the 12th OxC (0 eT). As a result, it will heat it to 1 eT, and itself will cool to 1 eT. Next, the 8th TR (1 eT) will balance the temperature of the reactor vessel (1 eT). Since there is no temperature difference, nothing happens.

• 9 - OxC (3 eT) will cool to 2 eT.
• 10 - OxC (2 eT) will cool to 1 eT.
• 11 - TVEL will allocate 8 eT (2 cycles of 4 eT each) to the 10th OxC (1 eT), which will heat it to 9 eT, and to the 13th TP (0 eT), which will heat it to 8 eT.

In the figure, red arrows show heating from uranium rods, blue arrows show heat balancing by heat distributors, yellow arrows show energy distribution to the reactor vessel, brown arrows show the final heating of elements at this step, blue arrows show cooling for cooling capsules. The numbers in the upper right corner show the final heating, and for uranium rods, the operating time.

Final heating after the first step:

• reactor vessel - 1 eT
• 1TP - 8 eT
• 2ОхС - 4еТ
• 4ОхС - 1еТ
• 5TP - 13 eT
• 7TP - 6 eT
• 8TP - 1 eT
• 9ОхС - 2еТ
• 10ОхС - 9еТ
• 12ОхС - 0еТ
• 13TP - 8 eT

Second step.

• The reactor vessel will cool to 0 eT.
• 1 - TP, do not take into account cooling.
• 2 - OxC (4 eT) will cool to 3 eT.
• 3 - TVEL will allocate 8 eT (2 cycles of 4 eT each) to the 1st TP (8 eT), which will heat it to 16 eT, and to the 2nd OxC (3 eT), which will heat it to 11 eT.
• 4 - OxC (1 eT) will cool to 0 eT.
• 5 - TP (13 eT) will balance the temperature with 2m OxC (11 eT). It will heat it up to 12 eT, and it will cool down to 12 eT.

Next, the 5th TP (12 eT) will balance the temperature at the 10th OxC (9 eT). It will heat it up to 10 eT, and it will cool down to 11 eT. Next, the 5th TP (11 eT) will balance the body temperature (0 eT), giving it 6 eT. The case will heat up to 6 eT, and the 5th TP will cool to 5 eT.

• 6 - TVEL will allocate 12 eT (3 cycles of 4 eT each) to the 5th TP (5 eT), which will heat it to 17 eT, and to the 7th TP (6 eT), which will heat it to 18 eT.
• 7 - TP (18 eT), do not take into account cooling.
• 8 - TP (1 eT) will balance the temperature of the 7th TP (18 eT) and take 6 eT from it. The 7th TP will cool to 12 eT, and the 8th TP will heat up to 7 eT.

Next, the 8th TP (7 eT) will balance the temperature at the 9th OxC (2 eT). As a result, it will heat it up to 4 eT, and itself will cool down to 5 eT. Next, the 8th TP (5 eT) will balance the temperature at the 4th OxC (0 eT). As a result, it will heat it to 2 eT, and itself will cool to 3 eT. Next, the 8th TP (3 eT) will balance the temperature at the 12th OxC (0 eT). As a result, it will heat it to 1 eT, and itself will cool to 2 eT. Next, the 8th TR (2 eT) will balance the temperature of the reactor vessel (6 eT), taking 2 eT from it. The case will cool down to 4 eT, and the 8th TP will heat up to 4 eT.

• 9 - OxC (4 eT) will cool to 3 eT.
• 10 - OxC (10 eT) will cool to 9 eT.
• 11 - TVEL will allocate 8 eT (2 cycles of 4 eT each) to the 10th OxC (9 eT), which will heat it to 17 eT, and to the 13th TP (8 eT), which will heat it to 16 eT.
• 12 - OxC (1 eT) will cool to 0 eT.
• 13 - TP (8 eT), do not take into account cooling.

Final heating after the second step:

• reactor vessel - 4 eT
• 1TP - 16 eT
• 2ОхС - 12 eT
• 4ОхС - 2еТ
• 5TP - 17 eT
• 7TP - 12 eT
• 8TP - 4 eT
• 9ОхС - 3еТ
• 10ОхС - 17еТ
• 12ОхС - 0еТ
• 13TP - 16 eT