Why is natural uranium enriched? Uranium: properties, application, extraction, compounds, enrichment. The largest uranium mining deposits in the world - leading countries

The use of uranium in technology

Summary section

The main areas of application of uranium.

Development of nuclear power. Achieved level and prospects. Estimation of the amount of uranium required for these purposes.

Uranium reserves and uranium mining industry. The level of production of uranium concentrates. Trends and conjuncture in the development of production and consumption of uranium.

The main stages (processing) in the technology of obtaining compounds, metal, uranium alloys, the manufacture of fuel elements (TVEL) and fuel assemblies (FA).

Uranium is a radioactive element and its applications are largely determined by its isotopic composition. Natural uranium consists of three isotopes:

The specific radioactivity of natural uranium is 0.67 microcurie/g (divided almost in half between U-234 and U-238, U-235 makes a small contribution). Natural uranium is radioactive enough to light up a photographic plate in about an hour.

Also in ancient times(1st century BC) natural uranium oxide was used to make a yellow glaze for ceramics. Shards of yellow-glazed pottery (containing more than 1% uranium oxide) have been found among the ruins of Pompeii and Herculaneum. The appearance of uranium glass is estimated at least as early as 79 AD, dated to a mosaic found in a Roman villa at Cape Posillipo in the Gulf of Naples (Italy) in 1912 and containing yellow glass containing about 1% uranium oxide (see Fig. Additional materials to section 3). Starting from the end of the Middle Ages pitchblende (uranite) began to be mined from the silver mines of the Habsburgs near the town of Jachymov in Bohemia (now Jachymov, Czech Republic) and was used as a dye in the local glass industry.

In modern history, the first use of technologically produced uranium compounds was also the preparation of colored (mainly red, orange and brown) glazes for pottery, as well as the manufacture of uranium glass, which has a yellow-green color and can fluoresce when exposed to sunlight or ultraviolet light.

Widespread production of uranium glass products was started in Europe in the 20-30s XIX years century and continued until the 1950s. Bohemian master Joseph Riedl developed a method for melting glass of new shades - yellow and green, and uranium dye gave them such a mysterious glow. Riedl was engaged in the production of uranium glass products from 1830 to 1848. In the 1830s, newfangled uranium glass began to be produced in Russia at the Gusevsky plant. For uranium glasses, calcium, zinc, barium compositions are recommended, preferably with a high content of potassium and boron, this provides a more intense fluorescence of the glass. Lead glasses do not fluoresce because they absorb ultraviolet rays. For uranium glasses without fluorescence, lead glass compositions can also be used, for example, in jewelry to imitate topaz - such glasses have a yellow color comparable to topazes. The content of uranium must be relatively high, since the coloring power of uranium in glass compositions is low. The content of uranium varies from 0.3...1.5% UO 3 to 4...6% UO 3 . However, with a higher introduction of uranium oxide, the fluorescence of the glass gradually weakens. Uranium is introduced into the charge in the form of oxides (UO 2 , U 3 O 8 or UO 3), sodium uranate (Na 2 UO 4 or Na 2 U 2 O 7) or uranyl nitrate.



Currently, a small amount of uranium glass and products from it is produced in the Czech Republic. Also, uranium is introduced into some types of optical glasses, for example, yellow ZhS19 borosilicate optical glass containing 1.37% UO 3 , or green ZS7 zinc phosphate optical glass containing 2.8% UO 3 .

The greatest application in modern technology has an isotope of uranium 235 U, in which a self-sustaining nuclear chain reaction is possible. Therefore, this isotope is used as fuel in nuclear reactors as well as in nuclear weapons. Isolation of the U 235 isotope from natural uranium is difficult technological problem. The degree of U-235 enrichment in nuclear fuel for nuclear power plants ranges from 2-4.5%, for weapons use - at least 80%, and more preferably 90%. In the US, weapons-grade uranium-235 is enriched to 93.5%; industry is capable of producing 97.65% - uranium of this quality is used in reactors for navy. In 1998, the Oak Ridge National Laboratory (ORNL) Isotope Division supplied 93% U-235 at $53/g.

The isotope U 238 is capable of fission under the influence of bombardment with high-energy neutrons, this feature is used to increase the power of thermonuclear weapons (neutrons generated by a thermonuclear reaction are used). Thermonuclear warheads often contain a layer of depleted uranium surrounding the main thermonuclear charge. This layer initially serves as a reaction mass, which makes it possible to achieve a stronger compression during detonation and a more complete occurrence of a thermonuclear reaction. The high flux of high-energy neutrons resulting from a thermonuclear reaction leads to the fission of U-238, which increases the power of the warhead. Such weapons are classified as fission-fusion-fission weapons, representing three successive stages of the explosion. The energy released during the final fission of depleted uranium is a significant fraction of the total power of a thermonuclear device. For example, 77% of the 10.4 megaton yield of Ivy Mike's fusion explosion in 1952 came from the fission of depleted uranium. Since depleted uranium does not have a critical mass, it can be added to a thermonuclear charge in almost unlimited quantities. The power released during the testing of the "king of the bomb" in the USSR in 1961 was "only" 50 megatons (90% of which came from the thermonuclear reaction itself) because the depleted uranium was replaced with lead at the final stage of the assembly. Using depleted uranium, the explosion power would be 100 megatons.

An important area of ​​application for this uranium isotope is the production of plutonium-239. As a result of neutron capture followed by β-decay, 238 U can be converted into 239 Pu, which is then used as nuclear fuel. Any reactor fuel containing natural or partially enriched uranium in the 235th isotope contains a certain proportion of plutonium after the end of the fuel cycle.

After extraction of U-235 from natural uranium, the remaining material is called "depleted uranium", because. it is depleted in the 235th isotope. About 560 thousand tons of depleted uranium hexafluoride (UF 6) are stored in the USA, about 700 thousand tons are stored in Russia.

Depleted uranium is half as radioactive as natural uranium, mainly due to the removal of U-234 from it. Due to the fact that the main use of uranium is energy production, depleted uranium is a useless product with low economic value. Finding ways to use depleted uranium is a big challenge for enrichment companies.

Basically, its use is associated with the high density of uranium and its relatively low cost. The two most important uses for depleted uranium are for radiation shielding (strangely enough) and as ballast in aerospace applications such as aircraft control surfaces. Each Boeing 747 aircraft produced before the mid-1980s contains 400-1500 kg of depleted uranium for this purpose. The problem associated with the use of uranium in civil aircraft is that in the event of an accident, the uranium burns up in a fire and enters environment in the form of an oxide. When two Boeing 747s collided at Tenerife airport in 1977, 3,000 kg of uranium burned out in a fire. Another famous case an accident of this kind, which led to the entry of a crane into the environment, is a disaster in 1992 in Amsterdam. Boeing and McDonnell-Douglas do not currently use uranium counterweights in civilian aircraft.

Depleted uranium is largely used in oil well drilling in the form of percussion rods (wireline drilling), its weight plunging the tool into mud-filled wells. This material is also used in high-speed gyroscope rotors, large flywheels, as ballast in space descent vehicles and racing yachts. A somewhat unexpected application is the use of uranium in Formula 1 racing cars. Regulations require a minimum car weight of 600 kg, but designers initially try to reduce the weight as much as possible, and then bring it up to 600 kg by placing depleted uranium ballasts and achieving at the same time the best balance.

But the most famous use of depleted uranium is as cores for armor-piercing projectiles (sub-caliber projectiles with a super-heavy core). With a certain alloy with other metals and heat treatment (alloying with 2% Mo or 0.75-3.5% Ti, rapid quenching of the metal heated to 850 ° C in water or oil, further holding at 450 ° C for 5 hours) uranium metal become harder and stronger than steel (tensile strength > 1600 MPa). Combined with its high density, this makes hardened uranium extremely effective at penetrating armor, similar in effectiveness to the much more expensive single-crystal tungsten. The process of destruction of the armor is accompanied by the grinding of most uranium into dust, the penetration of dust into the protected object and its ignition in air from the other side. About 300 tons of depleted uranium remained on the battlefield during Desert Storm (mostly remnants of 30mm GAU-8 cannon shells from A-10 attack aircraft, each shell containing 272 grams of uranium alloy). The US Army uses uranium in shells for 120 or 105 mm tank guns (M1 Abrams and M60A3) and 25 mm M242 guns mounted on the M2 Bradley and LAV-AT. Bullets with uranium cores (caliber 20, 25 and 30 mm) are used by the Marine Corps, Air Force and US Navy. The Russian (Soviet) army has been using depleted uranium in tank gun shells since the late 1970s, mainly for the 115 mm gun of the T-62 tank and the 125 mm gun of the T-64, T-72, T-80 and T- 90. Shells for tank guns and naval guns containing depleted uranium are also used by the armies of Great Britain, Israel, France, China, Pakistan, etc. In total, such weapons are produced in 18 countries.

Due to its high density, depleted uranium is also used in modern tank armor (in the form of a "sandwich" between two sheets of armor steel), for example, M-1 Abrams tanks (modifications M1A1HA and M1A2) built after 1998.

Work is underway to replace lead with depleted uranium in the manufacture of counterweights for elevators and cranes.

uranium ( chemical element) uranium (chemical element)

URANIUM (lat. Uranium), U (read "uranium"), a radioactive chemical element with atomic number 92, atomic mass 238.0289. Actinoid. Natural uranium consists of a mixture of three isotopes: 238U, 99.2739%, with a half-life of T 1/2 \u003d 4.51 10 9 years, 235 U, 0.7024%, with a half-life T 1/2 \u003d 7.13 10 8 years, 234 U, 0.0057%, with a half-life T 1/2 = 2.45 10 5 years. 238 U (uranium-I, UI) and 235 U (actinouranium, AcU) are the founders of the radioactive series. Of the 11 artificially produced radionuclides with mass numbers 227-240, long-lived 233 U ( T 1/2 \u003d 1.62 10 5 years), it is obtained by neutron irradiation of thorium (cm. THORIUM).
Configuration of three outer electron layers 5 s 2 p 6 d 10 f 3 6s 2 p 6 d 1 7 s 2 , uranium refers to f-elements. It is located in IIIB group in the 7th period of the Periodic Table of the Elements. In compounds, it exhibits oxidation states +2, +3, +4, +5 and +6, valencies II, III, IV, V and VI.
The radius of the neutral atom of uranium is 0.156 nm, the radius of the ions: U 3 + - 0.1024 nm, U 4 + - 0.089 nm, U 5 + - 0.088 nm and U 6+ - 0.083 nm. The energies of successive ionization of an atom are 6.19, 11.6, 19.8, 36.7 eV. Electronegativity according to Pauling (cm. PAULING Linus) 1,22.
Discovery history
Uranium was discovered in 1789 by the German chemist M. G. Klaproth (cm. KLAPROT Martin Heinrich) in the study of the mineral "tar blende". Named after the planet Uranus, discovered by W. Herschel (cm. HERSHEL) in 1781. In the metallic state, uranium was obtained in 1841 by the French chemist E. Peligot (cm. PELIGO Eugene Melchior) when reducing UCl 4 with metallic potassium. The radioactive properties of uranium were discovered in 1896 by the Frenchman A. Becquerel (cm. Becquerel Antoine Henri).
Initially, uranium was assigned an atomic mass of 116, but in 1871 D. I. Mendeleev (cm. MENDELEEV Dmitry Ivanovich) came to the conclusion that it should be doubled. After the discovery of elements with atomic numbers from 90 to 103, the American chemist G. Seaborg (cm. SEABORG Glenn Theodore) came to the conclusion that these elements (actinides) (cm. actinoids) it is more correct to place in the periodic system in the same cell with element No. 89 actinium. This arrangement is due to the fact that actinides undergo completion of 5 f-electronic sublevel.
Being in nature
Uranium is a characteristic element for the granite layer and sedimentary shell of the earth's crust. Content in earth's crust 2.5 10 -4% by weight. AT sea ​​water the concentration of uranium is less than 10 -9 g/l; in total, sea water contains from 10 9 to 10 10 tons of uranium. Uranium is not found in free form in the earth's crust. About 100 uranium minerals are known, the most important of them are pitchblende U 3 O 8, uraninite (cm. URANINITE)(U,Th)O 2, uranium resin ore (contains uranium oxides of variable composition) and tyuyamunite Ca[(UO 2) 2 (VO 4) 2] 8H 2 O.
Receipt
Uranium is obtained from uranium ores containing 0.05-0.5% U. The extraction of uranium begins with the production of a concentrate. Ores are leached with solutions of sulfuric, nitric acids or alkali. The resulting solution always contains impurities of other metals. When separating uranium from them, differences in their redox properties are used. Redox processes are combined with ion exchange and extraction processes.
From the resulting solution, uranium is extracted in the form of oxide or tetrafluoride UF 4 using the metallothermic method:
UF 4 + 2Mg = 2MgF 2 + U
The resulting uranium contains small amounts of boron impurities. (cm. BOR (chemical element)), cadmium (cm. CADMIUM) and some other elements, the so-called reactor poisons. By absorbing neutrons produced during the operation of a nuclear reactor, they make uranium unsuitable for use as a nuclear fuel.
To get rid of impurities, metallic uranium is dissolved in nitric acid, obtaining uranyl nitrate UO 2 (NO 3) 2 . The uranyl nitrate is extracted from the aqueous solution with tributyl phosphate. The purification product from the extract is again converted into uranium oxide or tetrafluoride, from which the metal is again obtained.
Part of the uranium is obtained by regeneration of spent nuclear fuel in the reactor. All uranium regeneration operations are carried out remotely.
Physical and chemical properties
Uranium is a silvery white lustrous metal. Uranium metal exists in three allotropic (cm. ALLOTROPY) modifications. Up to 669°C stable a-modification with an orthorhombic lattice, parameters a= 0.2854nm, in= 0.5869 nm and with\u003d 0.4956 nm, density 19.12 kg / dm 3. From 669°C to 776°C, the b-modification with a tetragonal lattice is stable (parameters a= 1.0758 nm, with= 0.5656 nm). Up to a melting point of 1135°C, the g-modification with a cubic body-centered lattice is stable ( a= 0.3525 nm). Boiling point 4200°C.
The chemical activity of metallic uranium is high. In air, it is covered with an oxide film. Powdered uranium is pyrophoric; during the combustion of uranium and the thermal decomposition of many of its compounds in air, uranium oxide U 3 O 8 is formed. If this oxide is heated in an atmosphere of hydrogen (cm. HYDROGEN) at temperatures above 500 ° C, uranium dioxide UO 2 is formed:
U 3 O 8 + H 2 \u003d 3UO 2 + 2H 2 O
If uranyl nitrate UO 2 (NO 3) 2 is heated at 500°C, then, decomposing, it forms uranium trioxide UO 3 . In addition to uranium oxides of the stoichiometric composition UO 2 , UO 3 and U 3 O 8 , uranium oxide of the composition U 4 O 9 and several metastable oxides and oxides of variable composition are known.
When uranium oxides are fused with oxides of other metals, uranates are formed: K 2 UO 4 (potassium uranate), CaUO 4 (calcium uranate), Na 2 U 2 O 7 (sodium diuranate).
Interacting with halogens (cm. HALOGENS), uranium gives uranium halides. Among them, UF 6 hexafluoride is a yellow crystalline substance that is easily sublimated even at low heating (40-60°C) and is equally easily hydrolyzed by water. The most important practical value is uranium hexafluoride UF 6 . It is obtained by the interaction of metallic uranium, uranium oxides or UF 4 with fluorine or fluorinating agents BrF 3 , CCl 3 F (freon-11) or CCl 2 F 2 (freon-12):
U 3 O 8 + 6CCl 2 F 2 = UF 4 + 3COCl 2 + CCl 4 + Cl 2
UF 4 + F 2 = UF 6
or
U 3 O 8 + 9F 2 \u003d 3UF 6 + 4O 2
Fluorides and chlorides are known that correspond to the oxidation states of uranium +3, +4, +5 and +6. Uranium bromides UBr 3 , UBr 4 and UBr 5 , as well as uranium iodides UI 3 and UI 4 were obtained. Uranium oxyhalides such as UO 2 Cl 2 UOCl 2 and others have been synthesized.
When uranium interacts with hydrogen, uranium hydride UH 3 is formed, which has a high chemical activity. When heated, the hydride decomposes, forming hydrogen and powdered uranium. During the sintering of uranium with boron, depending on the molar ratio of the reactants and the process conditions, borides UB 2 , UB 4 and UB 12 arise.
With carbon (cm. CARBON) uranium forms three carbides UC, U 2 C 3 and UC 2 .
The interaction of uranium with silicon (cm. SILICON) silicides U 3 Si, U 3 Si 2 , USi, U 3 Si 5 , USi 2 and U 3 Si 2 were obtained.
Uranium nitrides (UN, UN 2 , U 2 N 3) and uranium phosphides (UP, U 3 P 4 , UP 2) have been obtained. With sulfur (cm. SULFUR) uranium forms a series of sulfides: U 3 S 5 , US, US 2 , US 3 and U 2 S 3 .
Metallic uranium dissolves in HCl and HNO 3 and slowly reacts with H 2 SO 4 and H 3 PO 4 . There are salts containing the uranyl cation UO 2 2+ .
In aqueous solutions, there are uranium compounds in oxidation states from +3 to +6. Standard oxidation potential of U(IV)/U(III) pair - 0.52 V, U(V)/U(IV) pair 0.38 V, U(VI)/U(V) pair 0.17 V, pair U(VI)/U(IV) 0.27. The U 3+ ion is unstable in solution, the U 4+ ion is stable in the absence of air. The UO 2 + cation is unstable and disproportionates into U 4+ and UO 2 2+ in solution. U 3+ ions have a characteristic red color, U 4+ ions are green, and UO 2 2+ ions are yellow.
In solutions, uranium compounds in the +6 oxidation state are the most stable. All uranium compounds in solutions are prone to hydrolysis and complex formation, the most strongly are U 4+ and UO 2 2+ cations.
Application
Uranium metal and its compounds are mainly used as nuclear fuel in nuclear reactors. A low-enriched mixture of uranium isotopes is used in stationary reactors of nuclear power plants. The product of a high degree of enrichment is in nuclear reactors operating on fast neutrons. 235 U is the source nuclear energy in nuclear weapons. 238 U serves as a source of secondary nuclear fuel - plutonium.
Physiological action
In microquantities (10 -5 -10 -8%) it is found in the tissues of plants, animals and humans. It accumulates to the greatest extent by some fungi and algae. Uranium compounds are absorbed in the gastrointestinal tract (about 1%), in the lungs - 50%. The main depots in the body: the spleen, kidneys, skeleton, liver, lungs and broncho-pulmonary lymph nodes. The content in organs and tissues of humans and animals does not exceed 10 -7 years.
Uranium and its compounds are highly toxic. Aerosols of uranium and its compounds are especially dangerous. For aerosols of water-soluble uranium compounds MPC in air is 0.015 mg/m 3 , for insoluble forms of uranium MPC is 0.075 mg/m 3 . When it enters the body, uranium acts on all organs, being a general cellular poison. The molecular mechanism of action of uranium is associated with its ability to inhibit the activity of enzymes. First of all, the kidneys are affected (protein and sugar appear in the urine, oliguria). With chronic intoxication, hematopoietic and nervous system disorders are possible.

encyclopedic Dictionary . 2009 .

See what "URANUS (chemical element)" is in other dictionaries:

    U (Uran, uranium; at O ​​= 16 atomic weight U = 240) the element with the highest atomic weight; all elements, by atomic weight, are placed between hydrogen and uranium. This is the heaviest member of the metal subgroup of group VI of the periodic system (see Chromium, ... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

    Uranium (U) Atomic number 92 Appearance simple matter Properties of an atom Atomic mass ( molar mass) 238.0289 a. e.m. (g / mol) ... Wikipedia

    Uranium (lat. Uranium), U, a radioactive chemical element of group III of the Mendeleev periodic system, belongs to the actinide family, atomic number 92, atomic mass 238.029; metal. Natural U. consists of a mixture of three isotopes: 238U √ 99.2739% ... ... Great Soviet Encyclopedia

    Uranium (chemical element)- URANIUM (Uranium), U, radioactive chemical element of group III of the periodic system, atomic number 92, atomic mass 238.0289; refers to actinides; metal, mp 1135°C. Uranium is the main element of nuclear energy (nuclear fuel), used in ... ... Illustrated Encyclopedic Dictionary Wikipedia

    - (Greek uranos sky). 1) the god of heaven, the father of Saturn, the oldest of the gods, in Greek. mythol. 2) a rare metal that has the appearance of silvery leaves in its pure state. 3) a large planet discovered by Herschel in 1781. Dictionary of foreign words included in ... ... Dictionary of foreign words of the Russian language

    Uranus:* Uranus (mythology) ancient Greek god. Son of Gaia * Uranus (planet) planet solar system* Uranus ( musical instrument) ancient Turkic and Kazakh musical wind instrument * Uranus (element) chemical element * Operation ... ... Wikipedia

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URANUS (the name in honor of the planet Uranus discovered shortly before him; lat. uranium * a. uranium; n. Uran; f. uranium; and. uranio), U, is a radioactive chemical element of group III of the periodic system of Mendeleev, atomic number 92, atomic mass 238.0289, refers to actinides. Natural uranium consists of a mixture of three isotopes: 238 U (99.282%, T 1/2 4.468.10 9 years), 235 U (0.712%, T 1/2 0.704.10 9 years), 234 U (0.006%, T 1/2 0.244.10 6 years). 11 artificial radioactive isotopes of uranium with mass numbers from 227 to 240 are also known.

Uranium was discovered in 1789 in the form of UO 2 by the German chemist M. G. Klaproth. Metallic uranium was obtained in 1841 by the French chemist E. Peligot. For a long time, uranium had a very limited use, and only with the discovery of radioactivity in 1896 did its study and use begin.

Properties of uranium

In the free state, uranium is a light gray metal; below 667.7°C it is characterized by rhombic (a=0.28538 nm, b=0.58662 nm, c=0.49557 nm) crystal cell(a-modification), in the temperature range of 667.7-774 ° C - tetragonal (a = 1.0759 nm, c = 0.5656 nm; R-modification), at a higher temperature - body-centered cubic lattice (a = 0 .3538 nm, g-modification). Density 18700 kg / m 3, melting t 1135 ° C, boiling t about 3818 ° C, molar heat capacity 27.66 J / (mol.K), electrical resistivity 29.0.10 -4 (Ohm.m), thermal conductivity 22, 5 W/(m.K), temperature coefficient of linear expansion 10.7.10 -6 K -1 . The transition temperature of uranium to the superconducting state is 0.68 K; weak paramagnet, specific magnetic susceptibility 1.72.10 -6 . Nuclei 235 U and 233 U fission spontaneously, as well as during the capture of slow and fast neutrons, 238 U fissions only during the capture of fast (more than 1 MeV) neutrons. When slow neutrons are captured, 238 U turns into 239 Pu. The critical mass of uranium (93.5% 235U) in aqueous solutions is less than 1 kg, for an open ball about 50 kg; for 233 U the critical mass is approximately 1/3 of the critical mass of 235 U.

Education and content in nature

The main consumer of uranium is nuclear power (nuclear reactors, nuclear power plants). In addition, uranium is used to produce nuclear weapons. All other fields of uranium use are of sharply subordinate importance.

In a message from the Ambassador of Iraq to the UN Mohammed Ali al-Hakim dated July 9, it says that at the disposal of extremists ISIS (Islamic State of Iraq and the Levant). The IAEA (International Atomic Energy Agency) hastened to declare that the nuclear substances used by Iraq earlier have low toxic properties, and therefore materials captured by the Islamists.

A U.S. government source familiar with the situation told Reuters that the uranium stolen by the militants is likely not enriched and therefore unlikely to be used to make nuclear weapons. The Iraqi authorities officially notified the United Nations about this incident and called for "preventing the threat of its use," RIA Novosti reports.

Uranium compounds are extremely dangerous. About what exactly, as well as about who and how can produce nuclear fuel, says AiF.ru.

What is uranium?

Uranium is a chemical element with atomic number 92, a silvery-white glossy metal, the periodic system is designated by the symbol U. In its pure form, it is slightly softer than steel, malleable, flexible, found in the earth's crust (lithosphere) and in sea water and in its pure does not occur. Nuclear fuel is made from uranium isotopes.

Uranium is a heavy, silvery-white, shiny metal. Photo: Commons.wikimedia.org / Original uploader was Zxctypo at en.wikipedia.

Radioactivity of uranium

In 1938 the German physicists Otto Hahn and Fritz Strassmann irradiated the nucleus of uranium with neutrons and made a discovery: capturing a free neutron, the nucleus of the uranium isotope is divided and releases enormous energy due to the kinetic energy of the fragments and radiation. In 1939-1940 Julius Khariton and Yakov Zel'dovich for the first time theoretically explained that with a slight enrichment of natural uranium with uranium-235, it is possible to create conditions for continuous fission atomic nuclei, that is, to give the process a chain character.

What is enriched uranium?

Enriched uranium is uranium produced by technological process of increasing the proportion of the 235U isotope in uranium. As a result, natural uranium is divided into enriched uranium and depleted uranium. After the extraction of 235U and 234U from natural uranium, the remaining material (uranium-238) is called "depleted uranium", since it is depleted in the 235th isotope. According to some reports, about 560,000 tons of depleted uranium hexafluoride (UF6) are stored in the United States. Depleted uranium is half as radioactive as natural uranium, mainly due to the removal of 234U from it. Due to the fact that the main use of uranium is energy production, depleted uranium is a low-use product with low economic value.

Nuclear power uses only enriched uranium. The uranium isotope 235U has the greatest application, in which a self-sustaining nuclear chain reaction is possible. Therefore, this isotope is used as fuel in nuclear reactors and in nuclear weapons. Separation of the isotope U235 from natural uranium is a complex technology that few countries can implement. Uranium enrichment makes it possible to produce atomic nuclear weapons - single-phase or single-stage explosive devices in which the main energy output comes from the nuclear fission reaction of heavy nuclei with the formation of lighter elements.

Uranium-233, artificially produced in reactors from thorium (thorium-232 captures a neutron and turns into thorium-233, which decays into protactinium-233 and then into uranium-233), may in the future become a common nuclear fuel for nuclear power plants (already now there are reactors using this nuclide as fuel, for example KAMINI in India) and the production of atomic bombs (critical mass of about 16 kg).

The core of a 30 mm caliber projectile (GAU-8 guns of the A-10 aircraft) with a diameter of about 20 mm from depleted uranium. Photo: Commons.wikimedia.org / Original uploader was Nrcprm2026 at en.wikipedia

Which countries produce enriched uranium?

  • France
  • Germany
  • Holland
  • England
  • Japan
  • Russia
  • China
  • Pakistan
  • Brazil

10 countries providing 94% of the world's uranium production. Photo: Commons.wikimedia.org / KarteUrangewinnung

Why are uranium compounds dangerous?

Uranium and its compounds are toxic. Aerosols of uranium and its compounds are especially dangerous. For aerosols of water-soluble uranium compounds, the maximum allowable concentration(MPC) in air 0.015 mg/m³, for insoluble forms of uranium MPC - 0.075 mg/m³. When it enters the body, uranium acts on all organs, being a general cellular poison. Uranium almost irreversibly, like many other heavy metals, binds to proteins, primarily to the sulfide groups of amino acids, disrupting their function. The molecular mechanism of action of uranium is associated with its ability to inhibit the activity of enzymes. First of all, the kidneys are affected (protein and sugar appear in the urine, oliguria). With chronic intoxication, hematopoietic and nervous system disorders are possible.

The use of uranium for peaceful purposes

  • A small addition of uranium gives a beautiful yellow-green color to the glass.
  • Sodium uranium is used as a yellow pigment in painting.
  • Uranium compounds were used as paints for painting on porcelain and for ceramic glazes and enamels (colored in colors: yellow, brown, green and black, depending on the degree of oxidation).
  • At the beginning of the 20th century, uranyl nitrate was widely used to enhance negatives and stain (tint) positives (photographic prints) brown.
  • Alloys of iron and depleted uranium (uranium-238) are used as powerful magnetostrictive materials.

Isotope - varieties of atoms of a chemical element that have the same atomic (ordinal) number, but different mass numbers.

Group III element of the periodic table, belonging to the actinides; heavy weakly radioactive metal. Thorium has a number of applications in which it sometimes plays an indispensable role. The position of this metal in the periodic system of elements and the structure of the nucleus predetermined its use in the field of peaceful use of atomic energy.

*** Oliguria (from the Greek oligos - small and ouron - urine) - a decrease in the amount of urine separated by the kidneys.

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