The explosion of an atomic bomb and its mechanism of action. Nuclear power plant: how it works

Hundreds of thousands of famous and forgotten gunsmiths of antiquity fought in search of the ideal weapon, capable of evaporating an enemy army with one click. From time to time, traces of these searches can be found in fairy tales that more or less plausibly describe a miracle sword or a bow that hits without missing.

Fortunately, technological progress moved so slowly for a long time that the real embodiment of the devastating weapon remained in dreams and oral stories, and later on the pages of books. The scientific and technological leap of the 19th century provided the conditions for the creation of the main phobia of the 20th century. The nuclear bomb, created and tested under real conditions, revolutionized both military affairs and politics.

History of the creation of weapons

For a long time it was believed that the most powerful weapons could only be created using explosives. The discoveries of scientists who worked with the smallest particles provided scientific evidence that with the help elementary particles enormous energy can be generated. The first in a series of researchers can be called Becquerel, who in 1896 discovered the radioactivity of uranium salts.

Uranium itself has been known since 1786, but at that time no one suspected its radioactivity. The work of scientists at the turn of the 19th and 20th centuries revealed not only special physical properties, but also the possibility of obtaining energy from radioactive substances.

The option of making weapons based on uranium was first described in detail, published and patented by French physicists, the Joliot-Curies in 1939.

Despite its value for weapons, the scientists themselves were resolutely against the creation of such a devastating weapon.

Having gone through the Second World War in the Resistance, in the 1950s the couple (Frederick and Irene), realizing the destructive power of war, advocated for general disarmament. They are supported by Niels Bohr, Albert Einstein and other prominent physicists of the time.

Meanwhile, while the Joliot-Curies were busy with the problem of the Nazis in Paris, on the other side of the planet, in America, the world's first nuclear charge was being developed. Robert Oppenheimer, who led the work, was given the broadest powers and enormous resources. The end of 1941 marked the beginning of the Manhattan Project, which ultimately led to the creation of the first combat nuclear warhead.

In the town of Los Alamos, New Mexico, the first production facilities for weapons-grade uranium were erected. Subsequently, similar nuclear centers appeared throughout the country, for example in Chicago, in Oak Ridge, Tennessee, and research was carried out in California. The best forces of the professors of American universities, as well as physicists who fled from Germany, were thrown into creating the bomb.

In the “Third Reich” itself, work on creating a new type of weapon was launched in a manner characteristic of the Fuhrer.

Since “Besnovaty” was more interested in tanks and planes, and the more the better, he did not see much need for a new miracle bomb.

Accordingly, projects not supported by Hitler in best case scenario moved at a snail's pace.

When things started to get hot, and it turned out that the tanks and planes were swallowed up by the Eastern Front, the new miracle weapon received support. But it was too late; in conditions of bombing and constant fear of Soviet tank wedges, it was not possible to create a device with a nuclear component.

Soviet Union was more attentive to the possibility of creating a new type of destructive weapon. In the pre-war period, physicists collected and consolidated general knowledge about nuclear energy and the possibility of creating nuclear weapons. Intelligence worked intensively throughout the entire period of the creation of the nuclear bomb both in the USSR and in the USA. The war played a significant role in slowing down the pace of development, as huge resources went to the front.

True, Academician Igor Vasilyevich Kurchatov, with his characteristic tenacity, promoted the work of all subordinate departments in this direction. Looking ahead a little, it is he who will be tasked with accelerating the development of weapons in the face of the threat of an American strike on the cities of the USSR. It was he, standing in the gravel of a huge machine of hundreds and thousands of scientists and workers, who would be awarded the honorary title of the father of the Soviet nuclear bomb.

World's first tests

But let's return to the American nuclear program. By the summer of 1945, American scientists managed to create the world's first nuclear bomb. Any boy who has made himself or bought a powerful firecracker in a store experiences extraordinary torment, wanting to blow it up as quickly as possible. In 1945, hundreds of American soldiers and scientists experienced the same thing.

On June 16, 1945, the first ever nuclear weapons test and one of the most powerful explosions to date took place in the Alamogordo Desert, New Mexico.

Eyewitnesses watching the explosion from the bunker were amazed by the force with which the charge exploded at the top of the 30-meter steel tower. At first, everything was flooded with light, several times stronger than the sun. Then a fireball rose into the sky, turning into a column of smoke that took shape into the famous mushroom.

As soon as the dust settled, researchers and bomb creators rushed to the site of the explosion. They watched the aftermath from lead-encrusted Sherman tanks. What they saw amazed them; no weapon could cause such damage. The sand melted to glass in some places.

Tiny remains of the tower were also found; in a crater of huge diameter, mutilated and crushed structures clearly illustrated the destructive power.

Damaging factors

This explosion provided the first information about the power of the new weapon, about what it could use to destroy the enemy. These are several factors:

• light radiation, flash, capable of blinding even protected organs of vision;
• shock wave, a dense stream of air moving from the center, destroying most buildings;
• an electromagnetic pulse that disables most equipment and does not allow the use of communications for the first time after the explosion;
• penetrating radiation, the most dangerous factor for those who have taken refuge from other damaging factors, is divided into alpha-beta-gamma irradiation;
• radioactive contamination that can negatively affect health and life for tens or even hundreds of years.

The further use of nuclear weapons, including in combat, showed all the peculiarities of their impact on living organisms and nature. August 6, 1945 was the last day for tens of thousands of residents of the small city of Hiroshima, then known for several important military installations.

The outcome of the war in the Pacific was a foregone conclusion, but the Pentagon believed that the operation on the Japanese archipelago would cost more than a million lives of US Marines. It was decided to kill several birds with one stone, take Japan out of the war, saving on the landing operation, test a new weapon and announce it to the whole world, and, above all, to the USSR.

At one o'clock in the morning the plane carrying nuclear bomb"Baby" flew out on a mission.

The bomb, dropped over the city, exploded at an altitude of approximately 600 meters at 8.15 am. All buildings located at a distance of 800 meters from the epicenter were destroyed. The walls of only a few buildings, designed to withstand a magnitude 9 earthquake, survived.

Of every ten people who were within a radius of 600 meters at the time of the bomb explosion, only one could survive. The light radiation turned people into coal, leaving shadow marks on the stone, a dark imprint of the place where the person was. The ensuing blast wave was so strong that it could break glass at a distance of 19 kilometers from the explosion site.

One teenager was knocked out of the house through a window by a dense stream of air; upon landing, the guy saw the walls of the house folding like cards. The blast wave was followed by a fire tornado, destroying those few residents who survived the explosion and did not have time to leave the fire zone. Those at a distance from the explosion began to experience severe malaise, the cause of which was initially unclear to doctors.

Much later, a few weeks later, the term “radiation poisoning” was announced, now known as radiation sickness.

More than 280 thousand people became victims of just one bomb, both directly from the explosion and from subsequent illnesses.

The bombing of Japan with nuclear weapons did not end there. According to the plan, only four to six cities were to be hit, but weather conditions only allowed Nagasaki to be hit. In this city, more than 150 thousand people became victims of the Fat Man bomb.

Promises by the American government to carry out such attacks until Japan surrendered led to an armistice, and then to the signing of an agreement that ended World War. But for nuclear weapons this was just the beginning.

The most powerful bomb in the world

The post-war period was marked by the confrontation between the USSR bloc and its allies with the USA and NATO. In the 1940s, the Americans seriously considered the possibility of striking the Soviet Union. To contain the former ally, work on creating a bomb had to be accelerated, and already in 1949, on August 29, the US monopoly in nuclear weapons was ended. During the arms race, two nuclear tests deserve the most attention.

Bikini Atoll, known primarily for frivolous swimsuits, literally made a splash throughout the world in 1954 due to the testing of a specially powerful nuclear charge.

The Americans, having decided to test a new design of atomic weapons, did not calculate the charge. As a result, the explosion was 2.5 times more powerful than planned. Residents of nearby islands, as well as the ubiquitous Japanese fishermen, were under attack.

But it was not the most powerful American bomb. In 1960, the B41 nuclear bomb was put into service, but it never underwent full testing due to its power. The force of the charge was calculated theoretically, for fear of exploding such a dangerous weapon at the test site.

The Soviet Union, which loved to be the first in everything, experienced in 1961, otherwise nicknamed “Kuzka’s mother.”

Responding to America's nuclear blackmail, Soviet scientists created the most powerful bomb in the world. Tested on Novaya Zemlya, it left its mark in almost all corners of the globe. According to recollections, a slight earthquake was felt in the most remote corners at the time of the explosion.

The blast wave, of course, having lost all its destructive power, was able to circle the Earth. To date, this is the most powerful nuclear bomb in the world created and tested by mankind. Of course, if his hands were free, Kim Jong-un's nuclear bomb would be more powerful, but he does not have New Earth to test it.

Atomic bomb device

Let's consider a very primitive, purely for understanding, device of an atomic bomb. There are many classes of atomic bombs, but let’s consider three main ones:

• uranium, based on uranium 235, first exploded over Hiroshima;
• plutonium, based on plutonium 239, first exploded over Nagasaki;
• thermonuclear, sometimes called hydrogen, based on heavy water with deuterium and tritium, fortunately not used against the population.

The first two bombs are based on the effect of heavy nuclei fissioning into smaller ones through an uncontrolled nuclear reaction, releasing huge amounts of energy. The third is based on the fusion of hydrogen nuclei (or rather its isotopes of deuterium and tritium) with the formation of helium, which is heavier in relation to hydrogen. For the same bomb weight, the destructive potential of a hydrogen bomb is 20 times greater.

If for uranium and plutonium it is enough to bring together a mass greater than the critical one (at which a chain reaction begins), then for hydrogen this is not enough.

To reliably connect several pieces of uranium into one, a cannon effect is used in which smaller pieces of uranium are shot into larger ones. Gunpowder can also be used, but for reliability, low-power explosives are used.

In a plutonium bomb, to create the necessary conditions for a chain reaction, explosives are placed around ingots containing plutonium. Due to the cumulative effect, as well as the neutron initiator located in the very center (beryllium with several milligrams of polonium) the necessary conditions are achieved.

It has a main charge, which cannot explode on its own, and a fuse. To create conditions for the fusion of deuterium and tritium nuclei, we need unimaginable pressures and temperatures at at least one point. Next, a chain reaction will occur.

To create such parameters, the bomb includes a conventional, but low-power, nuclear charge, which is the fuse. Its detonation creates the conditions for the start of a thermonuclear reaction.

To estimate the power of an atomic bomb, the so-called “TNT equivalent” is used. An explosion is a release of energy, the most famous explosive in the world is TNT (TNT - trinitrotoluene), and all new types of explosives are equated to it. Bomb "Baby" - 13 kilotons of TNT. That is equivalent to 13000.

Bomb "Fat Man" - 21 kilotons, "Tsar Bomba" - 58 megatons of TNT. It’s scary to think of 58 million tons of explosives concentrated in a mass of 26.5 tons, that’s how much weight this bomb has.

The danger of nuclear war and nuclear disasters

Appearing in the midst of terrible war XX century, nuclear weapons became the greatest danger to humanity. Immediately after World War II, the Cold War began, several times almost escalating into a full-fledged nuclear conflict. The threat of the use of nuclear bombs and missiles by at least one side began to be discussed back in the 1950s.

Everyone understood and understands that there can be no winners in this war.

To contain it, efforts have been and are being made by many scientists and politicians. The University of Chicago, using the input of visiting nuclear scientists, including Nobel laureates, sets the Doomsday Clock a few minutes before midnight. Midnight signifies a nuclear cataclysm, the beginning of a new World War and the destruction of the old world. IN different years The clock hands fluctuated from 17 to 2 minutes to midnight.

There are also several known major accidents that occurred at nuclear power plants. These disasters have an indirect relation to weapons; nuclear power plants are still different from nuclear bombs, but they perfectly demonstrate the results of using the atom for military purposes. The largest of them:

• 1957, Kyshtym accident, due to a failure in the storage system, an explosion occurred near Kyshtym;
• 1957, Britain, in the north-west of England, security checks were not carried out;
• 1979, USA, due to an untimely detected leak, an explosion and release from a nuclear power plant occurred;
• 1986, tragedy in Chernobyl, explosion of the 4th power unit;
• 2011, accident at the Fukushima station, Japan.

Each of these tragedies left a heavy mark on the fate of hundreds of thousands of people and turned entire areas into non-residential zones with special control.

There were incidents that almost cost the beginning nuclear disaster. Soviet nuclear submarines have repeatedly had reactor-related accidents on board. The Americans dropped a Superfortress bomber with two Mark 39 nuclear bombs on board, with a yield of 3.8 megatons. But the activated “safety system” did not allow the charges to detonate and a disaster was avoided.

Nuclear weapons past and present

Today it is clear to anyone that nuclear war will destroy modern humanity. Meanwhile, the desire to possess nuclear weapons and enter the nuclear club, or rather, burst into it by knocking down the door, still excites the minds of some state leaders.

India and Pakistan created nuclear weapons without permission, and the Israelis are hiding the presence of a bomb.

For some, owning a nuclear bomb is a way to prove their importance on the international stage. For others, it is a guarantee of non-interference by winged democracy or other external factors. But the main thing is that these reserves do not go into business, for which they were really created.

Video

North Korea threatens the US with testing a super-powerful hydrogen bomb in the Pacific Ocean. Japan, which may suffer as a result of the tests, called North Korea's plans completely unacceptable. Presidents Donald Trump and Kim Jong-un argue in interviews and talk about open military conflict. For those who do not understand nuclear weapons, but want to be in the know, The Futurist has compiled a guide.

How do nuclear weapons work?

Like a regular stick of dynamite, a nuclear bomb uses energy. Only it is not released during the primitive chemical reaction, but in complex nuclear processes. There are two main ways to select nuclear energy from an atom. IN nuclear fission the nucleus of an atom decays into two smaller fragments with a neutron. Nuclear fusion – the process by which the Sun produces energy – involves the joining of two smaller atoms to form a larger one. In any process, fission or fusion, large amounts of thermal energy and radiation are released. Depending on whether nuclear fission or fusion is used, bombs are divided into nuclear (atomic) And thermonuclear .

Can you tell me more about nuclear fission?

Atomic bomb explosion over Hiroshima (1945)

As you remember, an atom is made up of three types of subatomic particles: protons, neutrons and electrons. The center of the atom, called core , consists of protons and neutrons. Protons are positively charged, electrons are negatively charged, and neutrons have no charge at all. The proton-electron ratio is always one to one, so the atom as a whole has a neutral charge. For example, a carbon atom has six protons and six electrons. Particles are held together by a fundamental force - strong nuclear force .

The properties of an atom can change significantly depending on how many different particles it contains. If you change the number of protons, you will have a different chemical element. If you change the number of neutrons, you get isotope the same element that you have in your hands. For example, carbon has three isotopes: 1) carbon-12 (six protons + six neutrons), which is a stable and common form of the element, 2) carbon-13 (six protons + seven neutrons), which is stable but rare, and 3) carbon -14 (six protons + eight neutrons), which is rare and unstable (or radioactive).

Most atomic nuclei are stable, but some are unstable (radioactive). These nuclei spontaneously emit particles that scientists call radiation. This process is called radioactive decay . There are three types of decay:

Alpha decay : The nucleus emits an alpha particle - two protons and two neutrons bound together. Beta decay : A neutron turns into a proton, electron and antineutrino. The ejected electron is a beta particle. Spontaneous fission: the nucleus disintegrates into several parts and emits neutrons, and also emits a pulse of electromagnetic energy - a gamma ray. It is the latter type of decay that is used in a nuclear bomb. Free neutrons emitted as a result of fission begin chain reaction , which releases a colossal amount of energy.

What are nuclear bombs made of?

They can be made from uranium-235 and plutonium-239. Uranium occurs in nature as a mixture of three isotopes: 238 U (99.2745% of natural uranium), 235 U (0.72%) and 234 U (0.0055%). The most common 238 U does not support a chain reaction: only 235 U is capable of this. To achieve maximum power explosion, it is necessary that the content of 235 U in the “filling” of the bomb is at least 80%. Therefore, uranium is produced artificially enrich . To do this, the mixture of uranium isotopes is divided into two parts so that one of them contains more than 235 U.

Typically, isotope separation leaves behind a lot of depleted uranium that is unable to undergo a chain reaction—but there is a way to make it do so. The fact is that plutonium-239 does not occur in nature. But it can be obtained by bombarding 238 U with neutrons.

How is their power measured?

​The power of a nuclear and thermonuclear charge is measured in TNT equivalent - the amount of trinitrotoluene that must be detonated to obtain a similar result. It is measured in kilotons (kt) and megatons (Mt). The yield of ultra-small nuclear weapons is less than 1 kt, while super-powerful bombs yield more than 1 mt.

The power of the Soviet “Tsar Bomb” was, according to various sources, from 57 to 58.6 megatons in TNT equivalent; the power of the thermonuclear bomb, which the DPRK tested in early September, was about 100 kilotons.

Who created nuclear weapons?

American physicist Robert Oppenheimer and General Leslie Groves

In the 1930s, Italian physicist Enrico Fermi demonstrated that elements bombarded by neutrons could be transformed into new elements. The result of this work was the discovery slow neutrons , as well as the discovery of new elements not represented on the periodic table. Soon after Fermi's discovery, German scientists Otto Hahn And Fritz Strassmann bombarded uranium with neutrons, resulting in the formation of a radioactive isotope of barium. They concluded that low-speed neutrons cause the uranium nucleus to break into two smaller pieces.

This work excited the minds of the whole world. At Princeton University Niels Bohr worked with John Wheeler to develop a hypothetical model of the fission process. They suggested that uranium-235 undergoes fission. Around the same time, other scientists discovered that the fission process produced even more neutrons. This prompted Bohr and Wheeler to ask an important question: could the free neutrons created by fission start a chain reaction that would release great amount energy? If this is so, then it is possible to create weapons of unimaginable power. Their assumptions were confirmed by a French physicist Frederic Joliot-Curie . His conclusion became the impetus for developments in the creation of nuclear weapons.

Physicists from Germany, England, the USA, and Japan worked on the creation of atomic weapons. Before the start of World War II Albert Einstein wrote to the US President Franklin Roosevelt that Nazi Germany plans to purify uranium-235 and create an atomic bomb. It now turns out that Germany was far from carrying out a chain reaction: they were working on a “dirty”, highly radioactive bomb. Be that as it may, the US government threw all its efforts into creating an atomic bomb as soon as possible. The Manhattan Project was launched, led by an American physicist Robert Oppenheimer and general Leslie Groves . It was attended by prominent scientists who emigrated from Europe. By the summer of 1945, atomic weapons were created based on two types of fissile material - uranium-235 and plutonium-239. One bomb, the plutonium “Thing,” was detonated during testing, and two more, the uranium “Baby” and the plutonium “Fat Man,” were dropped on the Japanese cities of Hiroshima and Nagasaki.

How does a thermonuclear bomb work and who invented it?

Thermonuclear bomb is based on the reaction nuclear fusion . Unlike nuclear fission, which can occur either spontaneously or forcedly, nuclear fusion is impossible without the supply of external energy. Atomic nuclei are positively charged - so they repel each other. This situation is called the Coulomb barrier. To overcome repulsion, these particles must be accelerated to crazy speeds. This can be done at very high temperatures - on the order of several million Kelvin (hence the name). There are three types of thermonuclear reactions: self-sustaining (take place in the depths of stars), controlled and uncontrolled or explosive - they are used in hydrogen bombs.

The idea of ​​a bomb with thermonuclear fusion initiated by an atomic charge was proposed by Enrico Fermi to his colleague Edward Teller back in 1941, at the very beginning of the Manhattan Project. However, this idea was not in demand at that time. Teller's developments were improved Stanislav Ulam , making the idea of ​​a thermonuclear bomb feasible in practice. In 1952, the first thermonuclear explosive device was tested on Enewetak Atoll during Operation Ivy Mike. However, it was a laboratory sample, unsuitable for combat. A year later, the Soviet Union detonated the world's first thermonuclear bomb, assembled according to the design of physicists Andrey Sakharov And Yulia Kharitona . The device resembled a layer cake, so the formidable weapon was nicknamed “Puff”. In the course of further development, the most powerful bomb on Earth, the “Tsar Bomba” or “Kuzka’s Mother,” was born. In October 1961, it was tested on the Novaya Zemlya archipelago.

What are thermonuclear bombs made of?

If you thought that hydrogen and thermonuclear bombs are different things, you were wrong. These words are synonymous. It is hydrogen (or rather, its isotopes - deuterium and tritium) that is required to carry out a thermonuclear reaction. However, there is a difficulty: in order to detonate a hydrogen bomb, it is first necessary to obtain a high temperature during a conventional nuclear explosion - only then atomic nuclei will begin to react. Therefore, in the case of a thermonuclear bomb, design plays a big role.

Two schemes are widely known. The first is Sakharov’s “puff pastry”. In the center was a nuclear detonator, which was surrounded by layers of lithium deuteride mixed with tritium, which were interspersed with layers of enriched uranium. This design made it possible to achieve a power within 1 Mt. The second is the American Teller-Ulam scheme, where the nuclear bomb and hydrogen isotopes were located separately. It looked like this: below there was a container with a mixture of liquid deuterium and tritium, in the center of which there was a “spark plug” - a plutonium rod, and on top - a conventional nuclear charge, and all this in a shell of heavy metal (for example, depleted uranium). Fast neutrons produced during the explosion cause atomic fission reactions in the uranium shell and add energy to the total energy of the explosion. Adding additional layers of lithium uranium-238 deuteride makes it possible to create projectiles of unlimited power. In 1953, Soviet physicist Victor Davidenko accidentally repeated the Teller-Ulam idea, and on its basis Sakharov came up with a multi-stage scheme that made it possible to create weapons of unprecedented power. “Kuzka’s Mother” worked exactly according to this scheme.

What other bombs are there?

There are also neutron ones, but this is generally scary. Essentially, a neutron bomb is a low-power thermonuclear bomb, 80% of the explosion energy of which is radiation (neutron radiation). It looks like a regular nuclear weapon low power, to which a block with a beryllium isotope is added - a source of neutrons. When a nuclear charge explodes, a thermonuclear reaction is triggered. This type of weapon was developed by an American physicist Samuel Cohen . It was believed that neutron weapons destroy all living things, even in shelters, but the range of destruction of such weapons is small, since the atmosphere scatters streams of fast neutrons, and the shock wave is stronger at large distances.

What about the cobalt bomb?

No, son, this is fantastic. Officially, no country has cobalt bombs. Theoretically, this is a thermonuclear bomb with a cobalt shell, which ensures strong radioactive contamination of the area even with a relatively weak nuclear explosion. 510 tons of cobalt can infect the entire surface of the Earth and destroy all life on the planet. Physicist Leo Szilard , who described this hypothetical design in 1950, called it the "Doomsday Machine".

What's cooler: a nuclear bomb or a thermonuclear one?

Full-scale model of "Tsar Bomba"

The hydrogen bomb is much more advanced and technologically advanced than the atomic one. Its explosive power far exceeds that of an atomic one and is limited only by the number of available components. In a thermonuclear reaction, much more energy is released for each nucleon (the so-called constituent nuclei, protons and neutrons) than in a nuclear reaction. For example, the fission of a uranium nucleus produces 0.9 MeV (megaelectronvolt) per nucleon, and the fusion of a helium nucleus from hydrogen nuclei releases an energy of 6 MeV.

Like bombs deliverto the goal?

At first they were dropped from airplanes, but air defense systems were constantly improving, and delivering nuclear weapons in this way turned out to be unwise. With the growth of missile production, all rights to deliver nuclear weapons were transferred to ballistic and cruise missiles of various bases. Therefore, a bomb now means not a bomb, but a warhead.

It is believed that the North Korean hydrogen bomb is too large to be mounted on a rocket - so if the DPRK decides to carry out the threat, it will be carried by ship to the explosion site.

What are the consequences of a nuclear war?

Hiroshima and Nagasaki are just a small part possible apocalypse. ​For example, the “nuclear winter” hypothesis is known, which was put forward by the American astrophysicist Carl Sagan and the Soviet geophysicist Georgy Golitsyn. It is assumed that the explosion of several nuclear warheads (not in the desert or water, but in populated areas) will cause many fires, and a large amount of smoke and soot will spill into the atmosphere, which will lead to global cooling. The hypothesis has been criticized by comparing the effect to volcanic activity, which has little effect on climate. In addition, some scientists note that global warming is more likely to occur than cooling - although both sides hope that we will never know.

Are nuclear weapons allowed?

After the arms race in the 20th century, countries came to their senses and decided to limit the use of nuclear weapons. The UN adopted treaties on the non-proliferation of nuclear weapons and the ban on nuclear tests (the latter was not signed by the young nuclear powers India, Pakistan, and the DPRK). In July 2017, a new treaty on the prohibition of nuclear weapons was adopted.

“Each State Party undertakes never under any circumstances to develop, test, produce, manufacture, otherwise acquire, possess or stockpile nuclear weapons or other nuclear explosive devices,” states the first article of the treaty. .

However, the document will not come into force until 50 states ratify it.

Let's look at a typical warhead (in reality, there may be design differences between warheads). This is a cone made of lightweight, durable alloys - usually titanium. Inside there are bulkheads, frames, power frame- almost like being on an airplane. The power frame is covered with durable metal casing. A thick layer of heat-protective coating is applied to the casing. It looks like an ancient Neolithic basket, generously coated with clay and fired in man's first experiments with heat and ceramics. The similarity is easy to explain: both the basket and the warhead have to resist external heat.

Warhead and its filling

Inside the cone, fixed to their “seats,” there are two main “passengers” for the sake of which everything was started: a thermonuclear charge and a charge control unit, or automation unit. They are amazingly compact. The automation unit is the size of a five-liter jar of pickled cucumbers, and the charge is the size of an ordinary garden bucket. Heavy and weighty, the union of a can and a bucket will explode three hundred fifty to four hundred kilotons. Two passengers are connected to each other by a connection, like Siamese twins, and through this connection they constantly exchange something. Their dialogue is ongoing all the time, even when the missile is on combat duty, even when these twins are just being transported from the manufacturing plant.

There is also a third passenger - a unit for measuring the movement of the warhead or generally controlling its flight. In the latter case, working controls are built into the warhead, allowing the trajectory to be changed. For example, actuating pneumatic systems or powder systems. And also an on-board electrical network with power supplies, communication lines with the stage, in the form of protected wires and connectors, protection against electromagnetic pulses and a thermostatting system - maintaining the required charge temperature.

The photo shows the breeding stage of the MX (Peacekeeper) rocket and ten warheads. This missile has long been withdrawn from service, but the same warheads are still used (and even older ones). The Americans have ballistic missiles with multiple warheads installed only on submarines.

After leaving the bus, the warheads continue to gain altitude and simultaneously rush towards their targets. They rise to the highest points of their trajectories, and then, without slowing down their horizontal flight, they begin to slide down faster and faster. At an altitude of exactly one hundred kilometers above sea level, each warhead crosses the formally man-designated boundary of outer space. Atmosphere ahead!

Electric wind

Below in front of the warhead lies a huge, contrastingly shiny from the menacing high altitudes, covered in a blue oxygen haze, covered with aerosol suspensions, the vast and boundless fifth ocean. Slowly and barely noticeably turning from the residual effects of separation, the warhead continues its descent along a gentle trajectory. But then a very unusual breeze gently blew towards her. He touched it a little - and it became noticeable, covering the body with a thin, receding wave of pale white-blue glow. This wave is breathtakingly high-temperature, but it does not burn the warhead yet, since it is too ethereal. The breeze blowing over the warhead is electrically conductive. The speed of the cone is so high that it literally crushes air molecules with its impact into electrically charged fragments, and impact ionization of the air occurs. This plasma breeze is called hypersonic flow large numbers Mach, and its speed is twenty times the speed of sound.

Due to the high rarefaction, the breeze is almost unnoticeable in the first seconds. Growing and becoming denser as it goes deeper into the atmosphere, it initially heats more than puts pressure on the warhead. But gradually it begins to squeeze her cone with force. The flow turns the warhead nose first. It does not unfold immediately - the cone sways slightly back and forth, gradually slowing down its oscillations, and finally stabilizes.

Heat on hypersonic

Condensing as it descends, the flow puts more and more pressure on the warhead, slowing down its flight. As it slows down, the temperature gradually decreases. From the enormous values ​​of the beginning of the entry, the blue-white glow of tens of thousands of Kelvin, to the yellow-white glow of five to six thousand degrees. This is the temperature of the surface layers of the Sun. The glow becomes dazzling because the air density quickly increases, and with it the heat flow into the walls of the warhead. The heat-protective coating becomes charred and begins to burn.

It does not burn from friction with the air, as is often incorrectly said. Due to the enormous hypersonic speed of movement (now fifteen times faster than sound), another cone diverges in the air from the top of the body - a shock wave, as if enclosing a warhead. The incoming air, entering the shock wave cone, is instantly compacted many times over and pressed tightly against the surface of the warhead. From abrupt, instantaneous and repeated compression, its temperature immediately jumps to several thousand degrees. The reason for this is the crazy speed of what is happening, the extreme dynamism of the process. Gas-dynamic compression of the flow, and not friction, is what now warms up the sides of the warhead.

The worst part is the nose. There the greatest compaction of the oncoming flow is formed. The area of ​​this seal moves slightly forward, as if disconnecting from the body. And it stays in front, taking the shape of a thick lens or pillow. This formation is called a “detached bow shock wave.” It is several times thicker than the rest of the surface of the shock wave cone around the warhead. The frontal compression of the oncoming flow is the strongest here. Therefore, the disconnected bow shock wave has the highest temperature and highest heat density. This small sun burns the nose of the warhead in a radiant way - highlighting, radiating heat directly into the nose of the hull and causing severe burning of the nose. Therefore, there is the thickest layer of thermal protection. It is the bow shock wave that illuminates the area on a dark night for many kilometers around a warhead flying in the atmosphere.

It becomes very unsweetening for the sides. They are now also being fried by the unbearable radiance from the head shock wave. And it burns with hot compressed air, which has turned into plasma from the crushing of its molecules. However, at such a high temperature, the air is ionized simply by heating - its molecules fall apart from the heat. The result is a mixture of impact-ionization and temperature plasma. Through its frictional action, this plasma polishes the burning surface of the thermal protection, as if with sand or sandpaper. Gas-dynamic erosion occurs, consuming the heat-protective coating.

At this time, the warhead passed the upper boundary of the stratosphere - the stratopause - and entered the stratosphere at an altitude of 55 km. It is now moving at hypersonic speeds, ten to twelve times faster than sound.

Inhuman overloads

Severe burning changes the geometry of the nose. The stream, like a sculptor’s chisel, burns a pointed central protrusion into the nasal covering. Other surface features also appear due to uneven burnout. Changes in shape lead to changes in flow. This changes the pressure distribution compressed air on the surface of the warhead and the temperature field. Variations in the force action of the air arise in comparison with the calculated flow, which gives rise to a deviation of the point of impact - a miss is formed. Even if it is small - say, two hundred meters, but the heavenly projectile will hit the enemy’s missile silo with a deflection. Or it won't hit at all.

In addition, the pattern of shock wave surfaces, bow waves, pressures and temperatures is constantly changing. The speed gradually decreases, but the air density quickly increases: the cone falls lower and lower into the stratosphere. Due to uneven pressures and temperatures on the surface of the warhead, due to the rapidity of their changes, thermal shocks can occur. They are able to break off pieces and pieces from the heat-protective coating, which introduces new changes into the flow pattern. And increases the deviation of the point of impact.

At the same time, the warhead can enter into spontaneous frequent swings with a change in the direction of these swings from “up-down” to “right-left” and back. These self-oscillations create local accelerations in different parts warheads. Accelerations vary in direction and magnitude, complicating the picture of the impact experienced by the warhead. It receives more loads, asymmetry of shock waves around itself, uneven temperature fields and other small delights that instantly grow into big problems.

But the oncoming flow does not exhaust itself with this either. Due to such powerful pressure from the oncoming compressed air, the warhead experiences an enormous braking effect. A large negative acceleration occurs. The warhead with all its internals is under rapidly increasing overload, and it is impossible to shield from overload.

Astronauts do not experience such overloads during descent. The manned vehicle is less streamlined and is not filled as tightly inside as the warhead. The astronauts are in no hurry to descend quickly. The warhead is a weapon. She must reach the target as quickly as possible before she is shot down. And the faster it flies, the more difficult it is to intercept it. The cone is the shape of the best supersonic flow. Having maintained a high speed to the lower layers of the atmosphere, the warhead encounters a very large deceleration there. This is why strong bulkheads and a load-bearing frame are needed. And comfortable “seats” for two riders - otherwise they will be torn from their seats by overload.

Dialogue of Siamese twins

By the way, what about these riders? The time has come to remember the main passengers, because they are not sitting passively now, but are going through their own difficult path, and their dialogue becomes most meaningful in these very moments.

The charge was disassembled into parts during transportation. When installed in a warhead, it is assembled, and when installing the warhead in a missile, it is equipped to a full combat-ready configuration (a pulsed neutron initiator is inserted, equipped with detonators, etc.). The charge is ready to travel to the target on board the warhead, but is not yet ready to explode. The logic here is clear: constant readiness of the charge to explode is unnecessary and theoretically dangerous.

It must be transferred to a state of readiness for explosion (near the target) by complex sequential algorithms based on two principles: reliability of movement towards the explosion and control over the process. The detonation system transfers the charge to ever higher levels of readiness in a strictly timely manner. And when the fully prepared charge comes from the control unit to detonate, the explosion will occur immediately, instantly. A warhead flying at the speed of a sniper’s bullet will only travel a couple of hundredths of a millimeter, not having time to move in space even the thickness of a human hair, when the thermonuclear reaction in its charge begins, develops, completely passes and is completed, releasing all the normal power.

Final Flash

Having changed greatly both outside and inside, the warhead passed into the troposphere - the last ten kilometers of altitude. She slowed down a lot. Hypersonic flight has degenerated to supersonic speed of three to four Mach units. The warhead is already shining dimly, fades away and approaches the target point.

An explosion on the surface of the Earth is rarely planned - only for objects buried in the ground, such as missile silos. Most targets lie on the surface. And for their greatest destruction, the detonation is carried out at a certain height, depending on the power of the charge. For tactical twenty kilotons this is 400-600 m. For a strategic megaton the optimal explosion height is 1200 m. Why? The explosion causes two waves to travel across the area. Closer to the epicenter, the blast wave will hit earlier. It will fall and be reflected, bouncing to the sides, where it will merge with the fresh wave that has just arrived here from above, from the point of explosion. Two waves - incident from the center of the explosion and reflected from the surface - add up, forming the most powerful shock wave in the ground layer, the main factor of destruction.

During test launches, the warhead usually reaches the ground unhindered. On board there is half a hundredweight of explosives, which are detonated when it falls. For what? First, the warhead is a secret object and must be securely destroyed after use. Secondly, this is necessary for the measuring systems of the test site - for prompt detection of the impact point and measurement of deviations.

A multi-meter smoking crater completes the picture. But before that, a couple of kilometers before the impact, an armored storage cassette is fired from the test warhead, recording everything that was recorded on board during the flight. This armored flash drive will protect against loss of on-board information. She will be found later, when a helicopter arrives with a special search group. And they will record the results of a fantastic flight.

The first intercontinental ballistic missile with a nuclear warhead

The world's first ICBM with nuclear warhead became the Soviet R-7. It carried one three-megaton warhead and could hit targets at a range of up to 11,000 km (modification 7-A). The brainchild of S.P. Although Korolev was put into service, it turned out to be ineffective as a military missile due to the inability to remain on combat duty for a long time without additional refueling with an oxidizer (liquid oxygen). But the R-7 (and its numerous modifications) played an outstanding role in space exploration.

The first ICBM warhead with multiple warheads

The world's first ICBM with a multiple warhead was the American LGM-30 Minuteman III missile, the deployment of which began in 1970. Compared to the previous modification, the W-56 warhead was replaced by three light W-62 warheads installed on the breeding stage. Thus, the missile could hit three separate targets or concentrate all three warheads to strike one. Currently, only one warhead is left on all Minuteman III missiles as part of the disarmament initiative.

Variable yield warhead

Since the early 1960s, technologies have been developed to create thermonuclear warheads with variable yield. These include, for example, the W80 warhead, which was installed, in particular, on the Tomahawk missile. These technologies were created for thermonuclear charges built according to the Teller-Ulam scheme, where the fission reaction of uranium or plutonium isotopes triggers a fusion reaction (that is, a thermonuclear explosion). The change in power occurred by making adjustments to the interaction of the two stages.

PS. I would also like to add that up there, the jamming units are also working on their task, false targets are released, and in addition, the booster units and/or the bus are blown up after disengagement in order to increase the number of targets on the radars and overload the missile defense system.

Nuclear power generation is a modern and rapidly developing method of producing electricity. Do you know how nuclear power plants work? What is the operating principle of a nuclear power plant? What types of nuclear reactors exist today? We will try to consider in detail the operation scheme of a nuclear power plant, delve into the structure of a nuclear reactor and find out how safe the nuclear method of generating electricity is.

Any station is a closed area far from a residential area. There are several buildings on its territory. The most important structure is the reactor building, next to it is the turbine room from which the reactor is controlled, and the safety building.

The scheme is impossible without a nuclear reactor. An atomic (nuclear) reactor is a nuclear power plant device that is designed to organize a chain reaction of neutron fission with the obligatory release of energy during this process. But what is the operating principle of a nuclear power plant?

The entire reactor installation is housed in the reactor building, a large concrete tower that hides the reactor and will contain all the products of the nuclear reaction in the event of an accident. This large tower is called containment, hermetic shell or containment zone.

The hermetic zone in new reactors has 2 thick concrete walls - shells.
The outer shell, 80 cm thick, protects the containment zone from external influences.

The inner shell, 1 meter 20 cm thick, has special steel cables that increase the strength of concrete almost three times and will prevent the structure from crumbling. WITH inside it is lined with a thin sheet of special steel, which is designed to serve as additional protection for the containment and, in the event of an accident, not to release the contents of the reactor outside the containment zone.

This design of the nuclear power plant allows it to withstand an airplane crash weighing up to 200 tons, a magnitude 8 earthquake, a tornado and a tsunami.

The first sealed shell was built at the American Connecticut Yankee nuclear power plant in 1968.

The total height of the containment zone is 50-60 meters.

What does a nuclear reactor consist of?

To understand the operating principle of a nuclear reactor, and therefore the operating principle of a nuclear power plant, you need to understand the components of the reactor.

• Active zone. This is the area where the nuclear fuel (fuel generator) and moderator are placed. Fuel atoms (most often uranium is the fuel) undergo a chain fission reaction. The moderator is designed to control the fission process and allows for the required reaction in terms of speed and strength.
• Neutron reflector. A reflector surrounds the core. It consists of the same material as the moderator. In essence, this is a box, the main purpose of which is to prevent neutrons from leaving the core and entering the environment.
• Coolant. The coolant must absorb the heat released during the fission of fuel atoms and transfer it to other substances. The coolant largely determines how a nuclear power plant is designed. The most popular coolant today is water.
  Reactor control system. Sensors and mechanisms that power a nuclear power plant reactor.

Fuel for nuclear power plants

What does a nuclear power plant operate on? Fuel for nuclear power plants are chemical elements with radioactive properties. At all nuclear power plants, this element is uranium.

The design of the stations implies that nuclear power plants operate on complex composite fuel, and not on a pure chemical element. And in order to extract uranium fuel from natural uranium, which is loaded into a nuclear reactor, it is necessary to carry out many manipulations.

Enriched uranium

Uranium consists of two isotopes, that is, it contains nuclei with different masses. They were named by the number of protons and neutrons isotope -235 and isotope-238. Researchers of the 20th century began to extract uranium 235 from ore, because... it was easier to decompose and transform. It turned out that such uranium in nature is only 0.7% (the remaining percentage goes to the 238th isotope).

What to do in this case? They decided to enrich uranium. Uranium enrichment is a process in which a lot of the necessary 235x isotopes remain in it and few unnecessary 238x isotopes. The task of uranium enrichers is to turn 0.7% into almost 100% uranium-235.

Uranium can be enriched using two technologies: gas diffusion or gas centrifuge. To use them, uranium extracted from ore is converted into a gaseous state. It is enriched in the form of gas.

Uranium powder

Enriched uranium gas is converted into a solid state - uranium dioxide. This pure solid uranium 235 appears as large white crystals, which are later crushed into uranium powder.

Uranium tablets

Uranium tablets are solid metal discs, a couple of centimeters long. To form such tablets from uranium powder, it is mixed with a substance - a plasticizer; it improves the quality of pressing the tablets.

The pressed pucks are baked at a temperature of 1200 degrees Celsius for more than a day to give the tablets special strength and resistance to high temperatures. How a nuclear power plant operates directly depends on how well the uranium fuel is compressed and baked.

The tablets are baked in molybdenum boxes, because only this metal is capable of not melting at “hellish” temperatures of over one and a half thousand degrees. After this, uranium fuel for nuclear power plants is considered ready.

What are TVEL and FA?

The reactor core looks like a huge disk or pipe with holes in the walls (depending on the type of reactor), 5 times larger than the human body. These holes contain uranium fuel, the atoms of which carry out the desired reaction.

It’s impossible to just throw fuel into the reactor, well, unless you want to cause an explosion of the entire station and an accident with consequences for a couple of nearby states. Therefore, uranium fuel is placed in fuel rods and then collected in fuel assemblies. What do these abbreviations mean?

• TVEL is a fuel element (not to be confused with the same name of the Russian company that produces them). It is essentially a thin and long zirconium tube made from zirconium alloys into which uranium tablets are placed. It is in fuel rods that uranium atoms begin to interact with each other, releasing heat during the reaction.

Zirconium was chosen as a material for the production of fuel rods due to its refractoriness and anti-corrosion properties.

The type of fuel rods depends on the type and structure of the reactor. As a rule, the structure and purpose of fuel rods does not change; the length and width of the tube can be different.

The machine loads more than 200 uranium pellets into one zirconium tube. In total, about 10 million uranium pellets are working simultaneously in the reactor.
FA – fuel assembly. NPP workers call fuel assemblies bundles.

Essentially, these are several fuel rods fastened together. FA is finished nuclear fuel, what a nuclear power plant operates on. It is the fuel assemblies that are loaded into the nuclear reactor. About 150 – 400 fuel assemblies are placed in one reactor.
Depending on the reactor in which the fuel assemblies will operate, they can be different shapes. Sometimes the bundles are folded into a cubic, sometimes into a cylindrical, sometimes into a hexagonal shape.

One fuel assembly over 4 years of operation produces the same amount of energy as when burning 670 cars of coal, 730 tanks with natural gas or 900 tanks loaded with oil.
Today, fuel assemblies are produced mainly at factories in Russia, France, the USA and Japan.

To deliver fuel for nuclear power plants to other countries, fuel assemblies are sealed in long and wide metal pipes, the air is pumped out of the pipes and delivered by special machines on board cargo planes.

Nuclear fuel for nuclear power plants weighs prohibitively much, because... uranium is one of the heaviest metals on the planet. His specific gravity 2.5 times more than steel.

Nuclear power plant: operating principle

What is the operating principle of a nuclear power plant? The operating principle of nuclear power plants is based on a chain reaction of fission of atoms of a radioactive substance - uranium. This reaction occurs in the core of a nuclear reactor.

IT IS IMPORTANT TO KNOW:

Without going into the intricacies of nuclear physics, the operating principle of a nuclear power plant looks like this:
After the start-up of a nuclear reactor, absorber rods are removed from the fuel rods, which prevent the uranium from reacting.

Once the rods are removed, the uranium neutrons begin to interact with each other.

When neutrons collide, a mini-explosion occurs at the atomic level, energy is released and new neutrons are born, a chain reaction begins to occur. This process generates heat.

Heat is transferred to the coolant. Depending on the type of coolant, it turns into steam or gas, which rotates the turbine.

The turbine drives an electric generator. It is he who actually generates the electric current.

If you do not monitor the process, uranium neutrons can collide with each other until they explode the reactor and smash the entire nuclear power plant to smithereens. The process is controlled by computer sensors. They detect an increase in temperature or change in pressure in the reactor and can automatically stop reactions.

How does the operating principle of nuclear power plants differ from thermal power plants (thermal power plants)?

There are differences in work only in the first stages. In a nuclear power plant, the coolant receives heat from the fission of atoms of uranium fuel; in a thermal power plant, the coolant receives heat from the combustion of organic fuel (coal, gas or oil). After either uranium atoms or gas and coal have released heat, the operation schemes of nuclear power plants and thermal power plants are the same.

Types of nuclear reactors

How a nuclear power plant works depends on how it works atomic reactor. Today there are two main types of reactors, which are classified according to the spectrum of neurons:
A slow neutron reactor, also called a thermal reactor.

For its operation, uranium 235 is used, which goes through the stages of enrichment, creation of uranium pellets, etc. Today, the vast majority of reactors use slow neutrons.
Fast neutron reactor.

These reactors are the future, because... They work on uranium-238, which is a dime a dozen in nature and there is no need to enrich this element. The only downside of such reactors is the very high costs of design, construction and startup. Today, fast neutron reactors operate only in Russia.

The coolant in fast neutron reactors is mercury, gas, sodium or lead.

Slow neutron reactors, which all nuclear power plants in the world use today, also come in several types.

Organization IAEA (international agency for nuclear energy) has created its own classification, which is most often used in the world nuclear energy industry. Since the operating principle of a nuclear power plant largely depends on the choice of coolant and moderator, the IAEA based its classification on these differences.

From a chemical point of view, deuterium oxide is an ideal moderator and coolant, because its atoms interact most effectively with neutrons of uranium compared to other substances. Simply put, heavy water performs its task with minimal losses and maximum results. However, its production costs money, while ordinary “light” and familiar water is much easier to use.

A few facts about nuclear reactors...

It’s interesting that one nuclear power plant reactor takes at least 3 years to build!
To build a reactor, you need equipment that operates on an electric current of 210 kiloamperes, which is a million times higher than the current that can kill a person.

One shell (structural element) of a nuclear reactor weighs 150 tons. There are 6 such elements in one reactor.

Pressurized water reactor

We have already found out how a nuclear power plant works in general; to put everything into perspective, let’s look at how the most popular pressurized water nuclear reactor works.
All over the world today, generation 3+ pressurized water reactors are used. They are considered the most reliable and safe.

All pressurized water reactors in the world, over all the years of their operation, have already accumulated more than 1000 years of trouble-free operation and have never given serious deviations.

The structure of nuclear power plants using pressurized water reactors implies that distilled water heated to 320 degrees circulates between the fuel rods. To prevent it from going into a vapor state, it is kept under pressure of 160 atmospheres. The nuclear power plant diagram calls it primary circuit water.

The heated water enters the steam generator and gives up its heat to the secondary circuit water, after which it “returns” to the reactor again. Outwardly, it looks like the water tubes of the first circuit are in contact with other tubes - the water of the second circuit, they transfer heat to each other, but the waters do not come into contact. The tubes are in contact.

Thus, the possibility of radiation entering the secondary circuit water, which will further participate in the process of generating electricity, is excluded.

NPP operational safety

Having learned the principle of operation of nuclear power plants, we must understand how safety works. The construction of nuclear power plants today requires increased attention to safety rules.
NPP safety costs account for approximately 40% of the total cost of the plant itself.

The nuclear power plant design includes 4 physical barriers that prevent the release of radioactive substances. What are these barriers supposed to do? At the right moment, be able to stop the nuclear reaction, ensure constant heat removal from the core and the reactor itself, and prevent the release of radionuclides beyond the containment (hermetic zone).

• The first barrier is the strength of uranium pellets. It is important that they are not destroyed by high temperatures in a nuclear reactor. Much of how a nuclear power plant operates depends on how the uranium pellets are “baked” during the initial manufacturing stage. If the uranium fuel pellets are not baked correctly, the reactions of the uranium atoms in the reactor will be unpredictable.
• The second barrier is the tightness of fuel rods. Zirconium tubes must be tightly sealed; if the seal is broken, then at best the reactor will be damaged and work will stop; at worst, everything will fly up into the air.
• The third barrier is a durable steel reactor vessel a, (that same large tower - hermetic zone) which “holds” all radioactive processes. If the housing is damaged, radiation will escape into the atmosphere.
• The fourth barrier is emergency protection rods. Rods with moderators are suspended above the core by magnets, which can absorb all neutrons in 2 seconds and stop the chain reaction.

If, despite the design of a nuclear power plant with many degrees of protection, it is not possible to cool the reactor core at the right time, and the fuel temperature rises to 2600 degrees, then the last hope of the safety system comes into play - the so-called melt trap.

The fact is that at this temperature the bottom of the reactor vessel will melt, and all the remains of nuclear fuel and molten structures will flow into a special “glass” suspended above the reactor core.

The melt trap is refrigerated and fireproof. It is filled with so-called “sacrificial material”, which gradually stops the fission chain reaction.

Thus, the nuclear power plant design implies several degrees of protection, which almost completely eliminate any possibility of an accident.

The device and principle of operation are based on the initialization and control of a self-sustaining nuclear reaction. It is used as a research tool, to produce radioactive isotopes, and as an energy source for nuclear power plants.

operating principle (briefly)

This uses a process in which a heavy nucleus breaks up into two smaller fragments. These fragments are in a highly excited state and emit neutrons, other subatomic particles and photons. Neutrons can cause new fissions, resulting in more of them being emitted, and so on. Such a continuous self-sustaining series of splittings is called a chain reaction. This releases a large amount of energy, the production of which is the purpose of using nuclear power plants.

The operating principle of a nuclear reactor is such that about 85% of the fission energy is released within a very short period of time after the start of the reaction. The rest is produced by the radioactive decay of fission products after they have emitted neutrons. Radioactive decay is a process in which an atom reaches a more stable state. It continues after division is completed.

In an atomic bomb, the chain reaction increases in intensity until it breaks down most of material. This happens very quickly, producing the extremely powerful explosions typical of such bombs. The design and operating principle of a nuclear reactor are based on maintaining a chain reaction at a controlled, almost constant level. It is designed in such a way that it cannot explode like an atomic bomb.

Chain reaction and criticality

The physics of a nuclear fission reactor is that the chain reaction is determined by the probability of the nucleus splitting after neutrons are emitted. If the population of the latter decreases, then the rate of division will eventually drop to zero. In this case, the reactor will be in a subcritical state. If the neutron population is maintained at a constant level, then the fission rate will remain stable. The reactor will be in critical condition. Finally, if the population of neutrons grows over time, the fission rate and power will increase. The state of the core will become supercritical.

The operating principle of a nuclear reactor is as follows. Before its launch, the neutron population is close to zero. Operators then remove control rods from the core, increasing nuclear fission, which temporarily pushes the reactor into a supercritical state. After reaching rated power, operators partially return the control rods, adjusting the number of neutrons. Subsequently, the reactor is maintained in a critical condition. When it needs to be stopped, operators insert the rods all the way. This suppresses fission and transfers the core to a subcritical state.

Reactor types

Most of the world's nuclear power plants are power plants, generating the heat needed to turn turbines that drive generators. electrical energy. There are also many research reactors, and some countries have submarines or surface ships powered by atomic energy.

Energy installations

There are several types of reactors of this type, but the light water design is widely used. In turn, it can use pressurized water or boiling water. In the first case, the liquid under high pressure is heated by the heat of the active zone and enters the steam generator. There, heat from the primary circuit is transferred to the secondary circuit, which also contains water. The ultimately generated steam serves as the working fluid in the steam turbine cycle.

The boiling-water reactor operates on the principle of a direct energy cycle. Water passing through the core is brought to a boil at medium pressure. The saturated steam passes through a series of separators and dryers located in the reactor vessel, which causes it to become superheated. The superheated water vapor is then used as working fluid, rotating the turbine.

High temperature gas cooled

A high-temperature gas-cooled reactor (HTGR) is a nuclear reactor whose operating principle is based on the use of a mixture of graphite and fuel microspheres as fuel. There are two competing designs:

• a German "fill" system that uses spherical fuel elements with a diameter of 60 mm, which are a mixture of graphite and fuel in a graphite shell;
• the American version in the form of graphite hexagonal prisms that interlock to create a core.

In both cases, the coolant consists of helium under a pressure of about 100 atmospheres. In the German system, helium passes through gaps in the layer of spherical fuel elements, and in the American system, helium passes through holes in graphite prisms located along the axis of the central zone of the reactor. Both options can operate at very high temperatures, since graphite has an extremely high sublimation temperature and helium is completely chemically inert. Hot helium can be applied directly as a working fluid in a gas turbine at high temperature, or its heat can be used to generate water cycle steam.

Liquid metal and working principle

Sodium-cooled fast reactors received much attention in the 1960s and 1970s. It seemed then that their breeding capabilities would soon be needed to produce fuel for the rapidly expanding nuclear industry. When it became clear in the 1980s that this expectation was unrealistic, enthusiasm waned. However, a number of reactors of this type have been built in the USA, Russia, France, Great Britain, Japan and Germany. Most of them run on uranium dioxide or its mixture with plutonium dioxide. In the United States, however, the greatest success has been achieved with metallic fuels.

CANDU

Canada is focusing its efforts on reactors that use natural uranium. This eliminates the need to resort to the services of other countries to enrich it. The result of this policy was the deuterium-uranium reactor (CANDU). It is controlled and cooled with heavy water. The design and operating principle of a nuclear reactor consists of using a reservoir of cold D 2 O at atmospheric pressure. The core is pierced by pipes made of zirconium alloy containing natural uranium fuel, through which heavy water that cools it circulates. Electricity is produced by transferring fission heat in heavy water to a coolant that circulates through a steam generator. The steam in the secondary circuit then passes through a conventional turbine cycle.

Research facilities

For scientific research Most often, a nuclear reactor is used, the operating principle of which is the use of water cooling and plate-shaped uranium fuel elements in the form of assemblies. Capable of operating over a wide range of power levels, from several kilowatts to hundreds of megawatts. Since power generation is not the primary purpose of research reactors, they are characterized by the thermal energy produced, the density and the nominal energy of the core neutrons. It is these parameters that help quantify the ability of a research reactor to conduct specific research. Low power systems are typically found in universities and used for teaching, while high power systems are needed in research laboratories for materials and performance testing and general research.

The most common is a research nuclear reactor, the structure and operating principle of which is as follows. Its core is located at the bottom of a large, deep pool of water. This simplifies the observation and placement of channels through which neutron beams can be directed. At low power levels there is no need to pump coolant as to maintain safe operating condition natural convection coolant provides sufficient heat removal. The heat exchanger is usually located on the surface or at the top of the pool where hot water accumulates.

Ship installations

The original and main application of nuclear reactors is their use in submarines. Their main advantage is that, unlike fossil fuel combustion systems, they do not require air to generate electricity. Therefore, a nuclear submarine can remain submerged for long periods of time, while a conventional diesel-electric submarine must periodically rise to the surface to fire its engines in mid-air. gives a strategic advantage to naval ships. Thanks to it, there is no need to refuel at foreign ports or from easily vulnerable tankers.

The operating principle of a nuclear reactor on a submarine is classified. However, it is known that in the USA it uses highly enriched uranium, and is slowed down and cooled by light water. The design of the first nuclear submarine reactor, USS Nautilus, was heavily influenced by powerful research facilities. Its unique features are a very large reactivity reserve, ensuring a long period of operation without refueling and the ability to restart after a stop. The power plant in submarines must be very quiet to avoid detection. To meet the specific needs of various classes of submarines were created different models power plants.

US Navy aircraft carriers use a nuclear reactor, the operating principle of which is believed to be borrowed from largest submarines. Details of their design have also not been published.

In addition to the United States, Great Britain, France, Russia, China and India have nuclear submarines. In each case, the design was not disclosed, but it is believed that they are all very similar - this is a consequence of the same requirements for them technical specifications. Russia also has a small fleet that uses the same reactors as Soviet submarines.

Industrial installations

For production purposes, a nuclear reactor is used, the operating principle of which is high productivity with a low level of energy production. This is due to the fact that a long stay of plutonium in the core leads to the accumulation of unwanted 240 Pu.

Tritium production

Currently, the main material produced by such systems is tritium (3H or T) - the charge for Plutonium-239 has a long half-life of 24,100 years, so countries with nuclear weapons arsenals using this element tend to have there is more of it than necessary. Unlike 239 Pu, tritium has a half-life of approximately 12 years. Thus, to maintain the necessary supplies, this radioactive isotope of hydrogen must be produced continuously. In the United States, Savannah River (South Carolina), for example, operates several heavy water reactors that produce tritium.

Floating power units

Nuclear reactors have been created that can provide electricity and steam heating remote isolated areas. In Russia, for example, small power plants specifically designed to serve Arctic settlements have found use. In China, the 10 MW HTR-10 provides heat and power to the research institute where it is located. Development of small automatically controlled reactors with similar capabilities is underway in Sweden and Canada. Between 1960 and 1972, the US Army used compact water reactors to power remote bases in Greenland and Antarctica. They were replaced by oil-fired power plants.

Conquest of space

In addition, reactors were developed for power supply and movement in outer space. Between 1967 and 1988, the Soviet Union installed small nuclear units on its Cosmos series satellites to power equipment and telemetry, but the policy became a target of criticism. At least one of these satellites entered the Earth's atmosphere, causing radioactive contamination in remote areas of Canada. The United States has launched only one nuclear-powered satellite, in 1965. However, projects for their use in long-distance space flights, manned exploration of other planets, or on a permanent lunar base continue to be developed. This will necessarily be a gas-cooled or liquid metal nuclear reactor, the physical principles of which will provide the highest possible temperature necessary to minimize the size of the radiator. In addition, the reactor for space technology must be as compact as possible to minimize the amount of material used for shielding and to reduce weight during launch and space flight. The fuel supply will ensure the operation of the reactor for the entire period of the space flight.