uranium

actinides A type of element , atomic number 92 .

One of the radioactive elements that exist in nature . The crystal structure is orthorhombic and the space group is Cmcm. exists in significant amounts in nature[2] It has the highest atomic number among the elements, and the transuranium atoms following uranium are considered artificial elements .

The origin of the name comes from Uranus (Οὐρανός) , the protogenoi god of Greek and Roman mythology . For this reason, people who are obsessed with the concept of using only pure Germanic English vocabulary called Anglish sometimes write ' Ymirstuff ' after the name of Ymir , the first giant and god with a similar position in Norse mythology .

1789 It was discovered to be contained in pitch blend by German chemist MH Klaproth, and was named after the new planet Uranus discovered outside Saturn in 1781.[3]

It was first isolated as a single element by EM Pelligo in France in 1842. Also, around 1896, A. Becquerel of France discovered radioactivity by noting the fact that uranium compounds pass through black paper and sensitize photographic plates .

Uranium is a silvery metal with abundant malleability and ductility , and is radioactive . Uranium is highly reactive, so it catches fire easily not only in the metal state but also in the dioxide state, especially when in powder form.[4] For reference, plutonium is similar. Although uranium had been discovered for a long time, it was not considered a dangerous substance.[5][6] For a heavy metal , it has weak chemical toxicity.[7] Due to its high density, it is even used as a radiation shield or armor material for tanks. It had several commercial uses. For example, adding uranium oxide to ceramics or glass made it emit a bright yellow-green light when exposed to ultraviolet rays . Uranium itself shows various colors depending on its chemical form.[8] Mohs hardness is 6.

Several isotopes exist in nature, and currently, 99.284% of the uranium on Earth is ²³⁸ U, with only 0.7% of ²³⁵ U , which is useful as nuclear fuel .[9] The main reason is the difference in half-life between the two . This is because the half-life of 235 (about 700 million years) is much shorter than that of 238 (about 4.5 billion years), and most ²³⁵ U has already collapsed and disappeared in the natural world. Therefore, it is assumed that about 4.5 billion years ago, when the Earth was first formed, the proportion of ²³⁵ U would have exceeded 20%.[10] If human civilization had been billions of years earlier, it would have been possible to run light water reactors using natural uranium .[11]

²³⁴ U accounts for a trace amount of about 0.0055% of natural uranium, and its half-life is short at 245,500 years, but it is part of the decay chain of ²³⁸ U, so it always exists in a certain amount in nature. It has no commercial use, but when producing small quantities for research purposes, it is obtained by extracting the decay products contained in old ²³⁸ Pu. ²³⁶ U, which has a half-life of 23.42 million years, is created with a probability of about 15% when ²³⁵ U absorbs neutrons in a nuclear reactor.[12] , Since it is non-fissile, it is not particularly useful and is treated as a nuisance that makes reuse difficult by increasing the radioactivity of uranium derived from spent nuclear fuel. ²³³ U, which has a half-life of 155,000 years , is a fissile isotope, and the idea is to use a thorium reactor to produce neutrons by irradiating 232 ^Th and use it for nuclear fission. During the Cold War, there was an attempt to use ²³³ U as a raw material for nuclear weapons, and an experiment was conducted to mix it with plutonium to create the core of a nuclear weapon and detonate it. However, when thorium is produced by irradiating neutrons, there is a problem that ²³² U, which emits strong gamma rays, is produced together when the content of ²³⁰ Th ( decay product of ²³⁸ U) is high or the energy of the neutron is high, so it is disadvantageous compared to plutonium, so it is not used to manufacture nuclear weapons. Using thorium, a fairly large amount of ²³³ U can be produced; about 2 tons was produced during the Cold War, and it is also used to produce radioactive isotopes for medical use.

Since it is a material used as nuclear fuel, it may seem like a rare resource, but in fact, uranium is a relatively common radioactive element. It is as abundant as tin based on the amount of crust, so it is surprisingly cheap. It is sold in the form of U ₃ O ₈ , and the market price is approximately $82 per pound as of October 2025 , which means about 118,000 won per kg of U ₃ O ₈ . That is why Cheonjo-guk can generously use depleted uranium for flying bullets and tank armor . Of course, if we limit it to 235, which is useful as nuclear fuel, it is as rare as platinum , and materials as high as plutonium are so expensive that they are difficult to use. For reference, the most common radioactive element is thorium .[13]

However, in the solar system, it is the rarest of the significant amounts of elements. Rather, gold or platinum is more common. Nevertheless, uranium is more common than gold/platinum in Earth's crust because it was possible to unite with other elements to remain crust.

The atomic bomb 'Little Boy' dropped on Hiroshima City in 1945 used uranium. The bomb destroyed more than 50,000 buildings and killed more than 75,000 people. Currently, most of uranium is used for nuclear power generation. The uranium that undergoes this type of nuclear fission is ²³⁵ U. The amount of ²³⁵ U that exists in nature is only 0.7% of the total uranium, but a lump of ²³⁵ U weighs at least 15 kg under ideal conditions.[14] , Under any conditions, if more than 40 kg gathers in a narrow range, it has the property of starting a chain reaction. The chain reaction of ²³⁵ U is possible with both fast and slow neutrons, and it is relatively easy to control depending on the reaction method, so nuclear reactors and atomic bombs can be made. In particular, it is almost the only radioactive isotope that can operate a stable nuclear reactor with current technology.[15][16]

To produce a practical nuclear explosion, it must be enriched at least 20%. Uranium with an enrichment level of more than 20% is called highly-enriched uranium (HEU). Typically, nuclear weapons use highly enriched weapons-grade uranium (more than 90%, usually 94-98%). Weapons-grade uranium is not only used in nuclear weapons, but is also used as nuclear fuel in special reactors such as nuclear submarines. The nuclear fuel of nuclear-powered submarines in countries such as the United States, the United Kingdom, and China also uses weapons-grade uranium of 90% to 94% to reduce the size of the reactor and extend the lifespan of fuel replacement.

However, if it is less than 90%, it does not mean that it cannot be used as a nuclear weapon. However, the critical mass increases significantly and the explosion efficiency decreases significantly. At about 20% enrichment, the critical mass required for minimum nuclear fission increases to a whopping 800 kg, and the explosion efficiency is extremely low, so the explosive power falls to the range of a large amount of conventional explosives, making it impractical as a nuclear weapon. Therefore, for peaceful commercial use of nuclear energy, low-enriched uranium (LEU) with an enrichment level of 20% or less is mainly used.

The more you try to enrich uranium to a higher concentration, the more effort it takes. The effort, equipment, and energy required to increase the enrichment level of uranium using a centrifuge, etc. are measured as a separation work unit (SWU). If the amount of work required to enrich 1 ton of natural metal uranium (0.7%) into 120 kg of 4.5% uranium suitable for a nuclear reactor is approximately 800 SWU, the amount of work required to produce 26 kg of 20% enriched uranium is approximately 1,100 SWU, and the amount of work required to produce 5.6 kg of 90% weapons-grade enriched uranium is approximately 1,300 SWU. In other words, raising the concentration from low-concentration uranium of 4.5% or 20% to 90% weapons-grade uranium does not require as much effort as expected because the amount of uranium that needs to be worked with is small.

In general, most light water reactors use uranium enriched to about 4.5%. Some heavy water reactors may use 0.7% enriched natural uranium, which is not enriched at all. Russia supplies about 40-50% of the world's demand for enriched uranium for light water reactors, and it is commercially supplied by several countries, including the United States, the United Kingdom, and France.

Some reactors, such as experiments used for the production and research of radioactive isotopes, or SMRs, which are attracting attention for recent technological developments, are using uranium of nearly 20% of low -concentrated uranium borders, such as 19.5% to reduce the size of the row and increase the fuel replacement cycle. Uranium, which is nearly 20% of the concentrated degree, is called high purity low concentration uranium. Haleu is currently not commercial mass supply, but Russia, the United Kingdom, and the United Kingdom, are under construction to build factories for commercial production and supply.

In a typical nuclear reactor (light water reactor), the concentration of ²³⁵ U must exceed a certain level, so it must first be dug up from a mine.[17] After making it into a concentrate , the concentrate is converted into uranium hexafluoride (UF ₆ ) gas and then enriched to increase the concentration to ²³⁵ U.[18] Concentration methods include a gas diffusion method (membrane method) that utilizes the fact that the diffusion rate of gas varies depending on molecular weight, a centrifugation method using isotope mass differences, and laser concentration using electronic energy levels or infrared absorption spectra. , most enrichment plants use gas diffusion or a more improved centrifugal separation method. The uranium remaining after enrichment is called depleted uranium . The process of processing enriched uranium into ceramic form and delivering it to a nuclear power plant is called the front end fuel cycle or open nuclear fuel cycle . In fact, if you include the post-nuclear cycle ( nuclear fuel reprocessing ), it will be longer, but if you keep it simple, this is the end.[19] This is the nuclear fuel cycle of a typical light water reactor, and in the case of a nuclear reactor (heavy water reactor) that uses natural uranium, such as CANDU or Magnox , the concentrate is converted, molded, and inserted without the need for an enrichment process. Of course, if these reactors are also concentrated, the reactor efficiency will increase.

Of course, the uranium enrichment process, like plutonium production, is a very sensitive matter, so if other countries build enrichment plants, those countries get angry. This can be clearly seen by looking at the United States' overreaction to Iran 's construction of an enrichment plant. For this reason, South Korea is using a complicated method in many ways, such as buying concentrate and sending it overseas, then processing the enriched uranium back into fuel domestically and using it . Currently, North Korea seems to want to negotiate with the United States over centrifuges. That's right, unlike plutonium production, uranium enrichment requires only uranium and electricity, so it can be made secretly. In the case of plutonium, the fuel rods must be melted.[20] The disadvantage is that radioactive materials fly out during the melting process, so they are quickly detected.

Of course, highly enriched uranium can also be used for nuclear weapons , so it is an element that the international community, including the United States, reacts very sensitively to. Former US President Barack Obama , who put forward the slogan of a “world without nuclear weapons,” hosted the Nuclear Security Summit from 2010 to 2016 with the goal of reducing nuclear weapons and nuclear materials and discussed the matter internationally . At the second summit held in Korea in 2012 , an international agreement was reached to convert research reactors using highly enriched uranium, which could be used for weapons, into low-enriched reactors.

Uranium in its natural state can mostly be found in pitch blend . The main ingredient in peach blend is uranium dioxide or yellowcake . Since pitch blend cannot be used directly as nuclear fuel, pitch blend must first be placed in a strong acid such as sulfuric acid to transform uranium into an ion state. An oxidizing agent is added to convert tetravalent uranium dioxide into hexavalent uranium, and then impurities such as thorium are removed using an organic solvent or ion exchange resin. To turn uranium into a solid again, it reacts with ammonia to form ammonium diuranate. At this time, ammonium diuranate sinks to the bottom of the solution. High-purity uranium dioxide can be obtained by heating the precipitate to form triuranium octoxide and then reacting it with hydrogen. When uranium dioxide is reacted with hydrofluoric acid , uranium tetrafluoride is produced, and when this is reduced with a strong reducing agent such as solid calcium, pure metallic uranium can be extracted. When pure uranium is taken out of solution, it reacts actively with oxygen to produce uranium dioxide again , so it must be stored in an inert gas environment. However, please be careful as it is a violation of the Nuclear Safety Act if an individual proceeds with this process without permission .

It is also used in archeology and geology. ²³⁸ U (half-life 4.468 billion years) undergoes alpha decay to become thorium -234, and a fission track remains in glassy minerals (obsidian, etc.), through which the age can be measured. However, because the half-life of uranium is so long, the minimum age that can be measured is more than 200,000 years, and if it is more than 900,000 years old, it is accurate with almost no error.

There is also glass containing uranium . It is called vaseline glass or canary glass, based on its transparent yellow color or uranium glass. Uranium glass is glass containing 0.01% uranium oxide, and is a traditional glass that has been made since the discovery of uranium. In the exhibition of the Curies and their spouses, the scraps minus the uranium ore appear, and the uranium was used to make this glass. It usually has a color between light yellow and light green with high saturation, and is a fluorescent glass that glows green when exposed to ultraviolet rays , as shown in the photo. It is definitely not luminous glass! It has very low radioactivity and is not dangerous to possess or use.

Ceramics until the 1940s It was also used in glaze . For this reason, trace amounts of radioactivity are often detected in antique ceramics, or they may emit a slight greenish glow under ultraviolet light, such as the uranium glass described above. By firing a glaze containing uranium, you can create gorgeous and vivid colors such as deep red, dark yellow, and ivory that are not normally obtainable. A representative example is the American Fiestaware, which was popular in the 1930s. Not all of Fiesta's products contain uranium, but the most famous colors and first introduced red and ivory products contain uranium. It disappeared in the 1940s when the atomic bomb was dropped on Hiroshima, and today it is sold at a high price as a collectible. Radioactivity is detected, but not at a dangerous level. However, its use is not recommended, and the problem of heavy metal poisoning is greater than that of radioactivity. This is because, like lead glaze and paint, it can dissolve in acidic foods.

Depleted uranium has very low radioactivity, so it is used for a variety of purposes. Due to its heavy weight, it is used as a weight or as a radiation shielding material. It is also used in weapons such as penetrators and armor plates that utilize high density. In addition, since radioactivity is low and nuclear fission does not occur until the half-life has elapsed, nuclear fission occurs when exposed to a large amount of neutrons, so it is used as fuel for fast breeder reactors or in the outer shell of hydrogen bombs to increase power.

Of course, uranium also emits radiation , but in real life, it is more dangerous to live in an old basement with no ventilation in an area with granite geology , to smoke a cigarette , to eat the detector part of an ion-type smoke alarm , or to use a self-luminous luminous watch or a very old-fashioned gas lamp . You don't have to be afraid of uranium alone because of these examples. Of course, if you put a Geiger counter tube against a glass containing uranium , it will react to radiation.

In addition, since uranium is clearly a heavy metal , it not only has radioactivity but is also highly toxic as a heavy metal itself. If you scoop up uranium and take a bite, you will die from heavy metal poisoning before you die from radiation. Also, even if it survives and is digested, the calories are low.
You die because 1g contains 18 to 20 billion calories.
The radioactivity of natural uranium is low, so shielding is either not done or only very thin until natural uranium fuel is loaded into the reactor. Of course, in the case of enriched uranium, the degree of shielding increases significantly.[21][22]

However, if you come in direct contact with it, you can be exposed to a greater amount of radiation than natural radiation . Assuming that you receive 2mSv/hr if you place a 2.6cm piece of uraniumite ( peach blend ) on your hand, the average environmental radiation in Korea is about 240 nSv/hr, so you can receive about 10,000 times the usual radiation exposure.[23] However, since the radiation emitted from natural uranium is alpha rays, it does not matter much as long as you do not ingest it. And there is a small amount of uranium in the human body that comes from food. However, like other elements, it is at a very trivial level, so you can rest assured. Of course, there is no reason to have uranium in your hands, and it is better not to do it just in case. To add, the parts of the body that are less affected by radiation than other parts of the body are the hands and feet, so if you must touch it near the body, touch it with the extremities.[24]

If you search for uranium in English on Google Image Search , you will see pictures of people suffering from various diseases, but there is no evidence that it is a mutation caused by radiation. It may be a chemical substance such as dioxin, or it may be a natural occurrence. And occasionally, you can see pictures of uranium glass.

There are rumors that North Korea has more than 4 million tons of uranium, 12 times the world's reserves (which is also the highest level). However, not only does this have no solid basis, but one of the materials believed to be the origin of the rumor is propaganda material from North Korea.[25][26] The North Korean uranium mine currently being mined is in North Hwanghae Province. It is in Pyeongsan-gun . It is located in Pyeongsan Mine, 3.5km northeast of Pyeongsan Station . In addition, it is said that miners who mine uranium in North Korea suffer from diseases of unknown origin and have short lifespans, and are said to avoid childbirth as they often give birth to deformed babies . #

In Canada , there is a place called Uranium City. This is where people who worked in the uranium mine near the area lived. In its heyday, there were about 5,000 people and CANDU High School, but since the mine closed in 1983, only eighty-nine people live there now.

Although there are currently no discovered uranium mines in Korea, it has been confirmed that there are uranium ore bodies in the area from Daejeon Metropolitan City to Geumsan-gun to Okcheon-gun . The reserves are up to 23.53 million tons , but the grade is low at about 0.35. It is not yet being developed because it is not profitable . However, because of this, the groundwater in the area contains trace amounts of uranium, and around 2004 , excessive amounts of uranium were detected in groundwater at KAIST and other sites, causing controversy. article The reason Yuseong Hot Springs is famous for its radon water is because of this uranium vein .

Then, from 2011 to 2014, an Australian mining company developed uranium ore bodies in the Daejeon and Geumsan areas and planned to supply the uranium to nuclear power plants in South Korea for 20 years. Of course, Daejeon citizens, Geumsan and Okcheon residents opposed it, and local governments also refused permission. That's because mines usually pollute the surrounding groundwater and ecosystem , and there are many cases of heavy metal poisoning among workers.[27] Build a mine far from the city. However, whether it is Daejeon or Okcheon, there is a population of 3 million (Daejeon + Sejong + Cheongju + Okcheon + Geumsan) nearby ...[28][29]

An element whose element symbol is a single letter in the Roman alphabet[30] It is the element with the highest atomic number . All elements with atomic numbers higher than uranium have two letters, and it is said that there is a policy of IUPAC that when a new element is discovered, the element symbol must be added with two letters when confirming the name.

Generally, the notoriety of the actinides is at the bottom, but uranium is an exceptionally prominent element because it is used in nuclear weapons, and plutonium , which is used for similar purposes , is as famous as uranium. It is also often used as an example of nuclear fission in textbooks.

China is said to have discovered 0-valent uranium in nature.

It is said that if all the uranium in our galaxy were collected, a sphere with a diameter exceeding 1 million km could be created. # If we assume that the source is correct and that the uranium density is constant, the total mass will be about 5 times the mass of the sun.[31]

There are instances where uranium absorption lines have been detected in some low-metal stars . Radioisotope dating can be useful in determining the age of stars, but the absorption lines are weak and often overlap with other metal lines.[32] Because the wavelength of the absorption line is mainly concentrated in the blue light or ultraviolet light, which has relatively large noise in spectroscopic observations, detection is difficult, so there are only a few stars in which uranium has been detected.

Since there are few opportunities for the general public to encounter it, various media depict it as a green gem or a metal that glows green in the dark. Actual uranium is a gray metal that looks dull and rough like lead , and neither metallic uranium nor uranium compounds glow in the dark. The appearance of uranium depicted in the media is probably derived from uranium glass, a glass containing uranium.[33] Uranium glass is green, and although it is not luminous, it fluoresces when exposed to ultraviolet light . Of course, uranium emits light on its own when certain conditions are met, but if you look at it up close, you will quickly die from acute radiation syndrome . Some uranium ores are actually green crystals (e.g. Torbernite) .[34] , Cu(UO ₂ ) ₂ (PO ₄ ) ₂ • 8 - 12 H ₂ O) is far from nuclear fuel. In general, uranium ore mined for nuclear fuel production is black pitchblende (UO ₂ ), and in reality, the color symbolizing uranium is rather yellow. Compounds containing uranyl (UO ₂ ²⁺ ), a hexavalent uranium ion, extracted from pitch blend, such as uranyl peroxide (UO ₄ ·nH ₂ O), are yellow, and yellow cake is now black, but is named yellow from this. The name stuck.

It is also used as a purified form of the swear word urajil.

Due to environmental issues and political reasons, investment in uranium mining technology has almost stopped worldwide. There are even projections that if investments to improve profitability are not made in a timely manner, there may be a shortage in 100 years, but perhaps because it is a story of a century later, there has been no significant improvement in the industry.