Uranium

{| border="1" cellpadding="2" cellspacing="0" align="right" | colspan="2" cellspacing="0" cellpadding="2" | {| align="center" border="0" | colspan="2" align="center" | protactinium – uranium – neptunium |- | rowspan="3" valign="center" | Neodymium
U

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Periodic table (standard)

|} |- ! colspan="2" align=center bgcolor="#ff99cc" | General |- | List of elements by name, List of elements by symbol, List of elements by number | Uranium, U, 92 |- | Chemical series | Actinides |- | periodic table period, periodic table block | period 7 element, f-block |- | Density, Mohs hardness scale | 19050 kilogram per cubic metre, 6 |- | color | align="center" | silvery-white metal
|- ! colspan="2" align="center" bgcolor="#ff99cc" | Atomic properties |- | Atomic weight | 1 E-25 kg |- | Atomic radius (calc.) | 1 E-10 m |- | Covalent radius | ND picometre |- | van der Waals radius | 186 pm |- | Electron configuration | [radon]7s-orbital²5f³6d-orbital¹ |- | electron 's per energy level | 2,8,18,32,21,9,2 |- | Oxidation states (Oxide) | 4,6 (weak base (chemistry)) |- | Crystal structure | Orthohombic |- ! colspan="2" align="center" bgcolor="#ff99cc" | Physical properties |- | State of matter | Solid (paramagnetic) |- | Melting point | 1405 Kelvin (2912 Fahrenheit) |- | Boiling point | 4091 K ( 6904 �F) |- | Molar volume | 12.49 scientific notation10^-6 cubic metre per mole |- | Heat of vaporization | 477 kilojoule per mole |- | Heat of fusion | 15.48 kJ/mol |- | Vapor pressure | ND Pascal at 2200 K |- | Velocity of sound | 3155 metre per second at 293.15 K |- ! colspan="2" align="center" bgcolor="#ff99cc" | Miscellaneous |- | Electronegativity | 1.38 (Pauling scale) |- | Specific heat capacity | 120 joule per kilogram-kelvin |- | Electrical conductivity | 3.8 10⁶/m ohm |- | Thermal conductivity | 27.6 watt per metre-kelvin |- | 1^st ionization potential | 597.6 kJ/mol |- | 2^nd ionization potential | 1420 kJ/mol |- ! colspan="2" align="center" bgcolor="#ff99cc" | Most stable isotopes |- | colspan="2" | {| border="1" cellspacing="0" cellpadding="2" width="100%" ! Isotope ! natural abundance ! half-life ! decay mode ! decay energy megaelectron volt ! decay product |- | ²³²U | synthetic radioisotope | 1 E9 s | alpha emission & spontaneous fission | 5.414 | ²²⁸thorium |- | ²³³U | {syn.} | 1 E12 s | SF & α | 4.909 | ²²⁹Th |- | Uranium-234 | 0.006% | 245,500 year | SF & α | 4.859 | ²³⁰Th |- | uranium-235 | 0.72% | 1 E16 s | SF & α | 4.679 | ²³¹Th |- | ²³⁶U | {syn.} | 1 E14 s | SF & α | 4.572 | ²³²Th |- | uranium-238 | 99.275% | 1 E17 s | SF & α | 4.270 | ²³⁴Th |} |- ! colspan="2" align="center" bgcolor="#ff99cc" | International System of Units units & standard temperature and pressure are used except where noted. |} Uranium is a chemical element in the periodic table that has the symbol U and atomic number 92. A heavy, silvery-white, toxic, metallic, and naturally-radioactivity element, uranium belongs to the actinide series and its isotope uranium-235 is used as the fuel for nuclear reactors and nuclear weapons. Uranium is commonly found in very small amounts in Rock (geology)s, soil, water, plants, and animals (including humans). == Notable characteristics == When refined, uranium is a silvery white, weakly radioactive metal, which is slightly softer than steel. It is malleable, ductile, and slightly paramagnetic. Uranium metal has very high density, 65% more dense than lead. When finely divided, it can react with cold water; in air, uranium metal becomes coated with uranium oxide. Uranium in ores can be extracted and chemically converted into uranium dioxide or other chemical forms usable in industry. Uranium metal has three allotrope forms: *alpha (orthorhombic) stable up to 667.7 °C *beta (tetragonal) stable from 667.7 °C to 774.8 °C *gamma (body-centered cubic) from 774.8 °C to melting point - this is the most malleable and ductile state. Its two principal isotopes are uranium-235 and uranium-238. Naturally-occurring uranium also contains a small amount of the Uranium-234 isotope, which is a decay product of ²³⁸U. The isotope ²³⁵U is important for both nuclear reactors and nuclear weapons because it is the only isotope existing in nature to any appreciable extent that is fissile, that is, fissionable by thermal neutrons. The isotope ²³⁸U is also important because it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope ²³⁹Pu (plutonium), which also is fissile. The artificial ²³³U isotope is also fissile and is made from ²³²thorium by neutron bombardment. Uranium was the first element that was found to be fissile, i.e. upon bombardment with slow neutrons, its ²³⁵U isotope becomes the very short lived ²³⁶U, that immediately divides into two smaller nuclei, liberating energy and more neutrons. If these neutrons are absorbed by other ²³⁵U nuclei, a nuclear chain reaction occurs, and if there is nothing to absorb some neutrons and slow the reaction, it is explosive. The first atomic bomb worked by this principle (nuclear fission). A more accurate name for both this and the hydrogen bomb (nuclear fusion) would be "nuclear weapon", because only the nuclei participate. ==Applications== Uranium metal is very dense and heavy. Depleted uranium (almost pure ²³⁸U with less than 0.2% ²³⁵U) is used by some military as shielding to protect tanks, and also in parts of bullets and missiles, as it is extremely dense. The military also uses enriched uranium (more than natural levels of ²³⁵U) to power nuclear propelled navy ships and submarines, and in nuclear weapons. Fuel used for United States Navy reactors is typically highly enriched in ²³⁵U (the exact values are classified information). In nuclear weapons uranium is also highly enriched, usually over 90% (again, the exact values are classified information) to a level known as "weapons grade". The main use of uranium in the civilian sector is to fuel commercial nuclear power plants, where fuel is typically enriched in ²³⁵U to 2-3%. However, the Canadian Candu reactors use natural unenriched uranium as fuel. Depleted uranium is used in helicopters and airplanes as counterweights on certain wing parts. Other uses include; *Ceramic glazes where small amounts of natural uranium (that is, not having gone through the enrichment process) may be added for color. * Addition of uranium makes fluorescent yellow or green colored glass. *The long half-life of the isotope ²³⁸U (4.51 × 10⁹ years) make it well-suited for use in estimating the age of the earliest igneous rocks and for other types of radiometric dating (including uranium-thorium dating and uranium-lead dating). *²³⁸U is converted into plutonium in breeder reactors. Plutonium can be used in reactors, or in nuclear weapons. *Uranyl acetate, UO₂(CH₃COO)₂ is used in analytical chemistry. It forms an insoluble salt with sodium. *Some lighting fixtures utilize uranium, as do some photography chemicals (esp. uranium nitrate). *Phosphate fertilizers often contain high amounts of natural uranium, because the mineral material from which they are made is typically high in uranium. *Uranium metal is used for X-ray targets in making of high-energy X-rays. *The element has found use in inertial guidance devices and in gyroscope compasses. == History == The use of uranium, in its natural oxide form, dates back to at least 79 AD, when it was used to add a yellow color to ceramic glazes (yellow glass with 1% uranium oxide was found near Naples, Italy). The discovery of the chemical elements of the element is credited to the German chemist Martin Heinrich Klaproth who in 1789 found uranium as part of the mineral called uraninite. It was named after the planet Uranus (planet), which had been discovered eight years earlier. It was first isolated as a metal in 1841 by Eugene-Melchior Peligot. In 1850 the first commercial use of Uranium in glass was developed by Lloyd & Summerfield of Birmingham. Uranium was found to be radioactivity by French physicist Henri Becquerel in 1896, who first discovered the process of radioactivity with uranium minerals. ===Military applications=== During the Manhattan Project, the wartime Allies program to develop the first atomic bombs during World War II, uranium gained new importance on the world political scene. Before the discovery of plutonium, only uranium was considered for the development of an atomic bomb, though the process of enriching it to applicable levels required gargantuan facilities (see Oak Ridge National Laboratory). Eventually enough uranium was enriched for one atomic bomb, which was dropped on Hiroshima, Hiroshima in 1945. The other nuclear weapons developed during the war used plutonium as their fissionable material, which itself requires uranium to produce. Initially it was believed that uranium was relatively rare, though within a decade large deposits of it were discovered in many places around the world. ===Uranium exploration and mining=== The exploration and mining of radioactive ores in the United States began around the turn of the 20th century. Sources for radium (contained in uranium ore) were sought for use as luminous paint for watch dials and other instruments, as well as for health-related applications (some of which in retrospect were incredibly unhealthy). Because of the need for the element during World War II, the Manhattan Project contracted with numerous vanadium mining companies in the American Southwest, and also purchased uranium ore from the Belgian Congo, through the Union Mini�re du Haut Katanga, and in Canada from the Eldorado Mining and Refining Limited company. American uranium ores mined in Colorado were primarily mixes of vanadium and uranium, but because of wartime secrecy the Manhattan Project would only publicly admit to purchasing the vanadium, and did not pay the uranium miners for the uranium ore (in a much later lawsuit, many miners were able to reclaim lost profits from the U.S. government). American uranium ores did not have nearly as high uranium concentrations as the ore from the Belgian Congo, but they were pursued vigorously to ensure nuclear self-sufficiency. Similar efforts were undertaken in the Soviet Union, which did not have native stocks of uranium when it started developing its own weapons program. ===Rise and subsequent stagnation of uranium mining=== In the beginning of the Cold War, to ensure adequate supplies of uranium for national defense, the United States Congress passed the U.S. Atomic Energy Act of 1946, creating the Atomic Energy Commission (AEC) which had the power to withdraw prospective uranium mining land from public purchase, and also to manipulate the price of uranium to meet national needs. By setting a high price for uranium ore, the AEC created a uranium "boom" in the early 1950s, which attracted many prospectors to the Four Corners (United States) of the country. Moab, Utah became known as the Uranium-capital of the world, when geologist Charles Steen discovered such an ore in 1952, even though American ore sources were considerably less potent than those in the Belgian Congo or South Africa. At the height of the nuclear energy euphoria in the 1950 methods for extracting diluted uranium and thorium found in abundance in granite or seawater was pursued. [http://www.ornl.gov/info/ornlreview/rev25-34/chapter4.shtm ORNL Review] Scientists promised that used in a breeder reactor these materials would potentially provide limitless source of energy. American military requirements declined in the 1960s, and the government completed its uranium procurement program by the end of 1970. Simultaneously, a new market emerged: commercial nuclear power plants. However, in the U.S. this market virtually collapsed by the end of the 1970s as a result of industrial strains caused by the energy crisis, popular opposition, and finally the Three Mile Island nuclear accident in 1979, all of which led to a ''de facto'' moratorium on the development of new nuclear reactor power stations. In Europe a mixed situation exists. Considerable nuclear power capacities have been developed, notably in France, Germany, Spain, Sweden, Switzerland and the UK. In many countries development of nuclear power has been stopped by legal actions. In Italy the use of nuclear power has been barred by a referendum in 1987. In France and Switzerland the use of nuclear power continues, but there is little new demand that would stimulate the market for uranium. Since 1981 uranium prices and quantities in the US are reported by the United States Department of Energy [http://www.eia.doe.gov/emeu/aer/pdf/pages/sec9.pdf]. Import price dropped from 32.90 US$/lb U₃O₈ in 1981 down to 12.55 in 1990 and to below 10 US$/lb U₃O₈ in the year 2000. Prices paid for uranium during the 1970s were higher, 43 US$/lb U₃O₈ is reported as the selling price for Australia uranium in 1978 by the [http://www.ccsa.asn.au/nic/Uranium/UMarket.htm Nuclear Information Centre]. ===Risks of uranium mining=== Because uranium ores emit radon gas, and their harmful and highly radioactive decay product, uranium mining is significantly more dangerous than other (already dangerous) hard rock mining, requiring adequate ventilation systems if the mines are not open-pit mining. During the 1950s, a significant amount of American uranium miners were Navajo Nation Indians, as many uranium deposits were discovered on Navajo Indian reservation. An unusually high number of these miners later developed lung cancer. Some survivors and their descendants received compensation under the Radiation Exposure Compensation Act in 1990. ===Codenames ''tuballoy'' and ''oralloy''=== During the Manhattan Project, the names ''tuballoy'' and ''oralloy'' were used to refer to natural uranium and enriched uranium respectively, originally for purposes of secrecy. These names are still used occasionally to refer to natural or enriched uranium. == Compounds == Uranium tetrafluoride (UF₄) is known as "green salt" and is an intermediate product in the production of uranium hexafluoride. Uranium hexafluoride (UF₆) is a white solid which forms a vapor at temperatures above 56 degrees Celsius. UF₆ is the compound of uranium used for the two most common enrichment processes, gaseous diffusion enrichment and gas centrifuge enrichment. It is simply called "hex" in the industry. [[Image:Yellowcake.jpg|right|thumb|Powdered yellowcake in a drum.]] Yellowcake is uranium concentrate. It takes its name from the color and texture of the concentrates produced by early mining operations, despite the fact that modern mills using higher calcining temperatures produce "yellowcake" that is dull green to almost black. Yellowcake typically contains 70 to 90 percent uranium oxide (U₃O₈) by weight. (Other uranium oxides, such as UO₂ and UO₃, exist; the most stable oxide, U₃O₈, is actually considered to be a 2:3 molar mixture of these.) Ammonium diuranate is an intermediate product in the production of yellowcake, and is bright yellow in colour. It is sometimes confusingly called "yellowcake" as well, but this is not a standard name. Uranyl nitrate (UO₂(NO₃)₂) is an extraordinarily toxic, soluble uranium salt. == Occurrence == Uranium is a naturally-occurring element found at low levels in virtually all rock, soil, and water. It is considered to be more plentiful than antimony, beryllium, cadmium, gold, mercury (element), silver, or tungsten and is about as abundant as arsenic or molybdenum. It is found in many minerals including uraninite (most common uranium ore), autunite, uranophane, torbernite, and coffinite. Significant concentrations of uranium occur in some substances such as phosphate rock deposits, and minerals such as lignite, and monazite sands in uranium-rich ores (it is recovered commercially from these sources). The decay of uranium and its nuclear reactions with thorium in the Earth's core is thought to be the source for much of the heat that keeps the outer core liquid, which in turn drives plate tectonics. Uranium ore is rock containing uranium mineralization in concentrations that can be mined economically, typically 1 to 4 pounds of uranium oxide per ton or 0.05 to 0.20 percent uranium oxide. ==Production and distribution== Commercial-grade uranium can be produced through the reduction of uranium halides with alkali or alkaline earth metals. Uranium metal can also be made through electrolysis of potassiumUfluorine₅ or UF₄, dissolved in a molten CaCl2 and NaCl. Very pure uranium can be produced through the thermal decomposition of uranium halides on a hot filament. Owners and operators of U.S. civilian nuclear power reactors purchased from U.S. and foreign suppliers a total of 21,300 tons of uranium deliveries during 2001. The average price paid was $26.39 per kilogram of uranium, a decrease of 16 percent compared with the 1998 price. In year 2001, the U.S. produced 1,018 tons of uranium from 7 mining operations, all of which are west of the Mississippi River. Uranium is distributed worldwide. Generally, large countries produce more uranium than smaller ones because the worldwide distribution of uranium is very roughly uniform. Canada is the world's largest producer of uranium, with the world's richest deposits in Saskatchewan. Saskatchewan through three large mines produces over a quarter of the world's uranium. Because of this production, extra capacity, and the close government control of the industry the provincial government plays a central role in setting international uranium prices. Australia also has extensive uranium deposits making up approximately 30% of the world's known uranium reserves. The world's largest single uranium deposit is located at the Olympic Dam Mine in South Australia. [http://www.uraniumsa.org/processing/processing.htm] [http://money.cnn.com/services/tickerheadlines/for5/200411231804DOWJONESDJONLINE000797_FORTUNE5.htm] The ultimate supply of uranium is very large. It is estimated that for every doubling of price, that the supply of uranium will be multiplied 2.5 times. A ten fold increase in price will result in an increase of supply of 300 times. == Isotopes == Naturally occurring uranium is composed of 3 major isotopes, ²³⁸U, ²³⁵U, and ²³⁴U, with ²³⁸U being the most abundant (99.3% natural abundance). These 3 isotopes are radioactive, creating radioisotopes, with the most abundant and stable being ²³⁸U with a half-life of 4.5 × 10⁹ years, ²³⁵U with a half-life of 7 × 10⁸ years, and ²³⁴U with a half-life of 2.5 × 10⁵ years. ²³⁸U is an α emitter, decaying into Lead-206. Uranium isotopes can be separated to increase the concentration of one isotope relative to another. This process is called "enrichment" (see enriched uranium). To be considered to be 'enriched' the ²³⁵U fraction has to be increased to significantly greater than the 0.711% (by weight) (eg typically to levels from 3% to 7%). ²³⁵U is typically the main fissile material for nuclear power reactors. Either ²³⁵U or ²³⁹Pu are used for making nuclear weapons. The process produces huge quantities of uranium that is depleted of ²³⁵U and with a correspondingly increased fraction of ²³⁸U, called depleted uranium or "DU". To be considered to be 'depleted', the ²³⁵U isotope concentration has to have been decreased to significantly less than 0.711% (by weight). Typically the amount of ²³⁵U left in depleted uranium is 0.2% to 0.3%. This represents anywhere from 28% to 42% of the original fraction of ²³⁵U. Given that the half life of ²³⁵U is considerably shorter than ²³⁸U, the "depleted" uranium is still significantly radioactive as is the natural uranium after refining. Another way to look at this is as follows: CANDU reactors use natural uranium (0.71% fissile material). From Pressurized water reactors (PWRs) of typical design (most USA reactors are PWR) we note the fuel goes in with about 4% ²³⁵U and 96% ²³⁸U and comes out with about 1% ²³⁵U, 1% ²³⁹Pu and 95% ²³⁸U. If the ²³⁹Pu were removed (fuel reprocessing is not allowed in the USA) and this were added to the "depleted uranium" then we would have 1.2% fissile material in the reprocessed "depleted uranium" and at the same time have 1% fissile material in the left over "spent" fuel. Both of these would be considered "enriched" fuels for a CANDU style reactor. == Precautions == ''All isotopes and compounds of uranium are toxic and radioactive.'' Toxicity can be lethal. In less than lethal doses toxicity is limited primarily to recoverable kidney damage. Radiological effects are systemic. Uranium compounds in general are poorly absorbed by the lining in the lungs and may remain a radiological hazard indefinitely. Finely-divided uranium metal presents a fire hazard. A person can be exposed to uranium by inhaling dust in air, or ingesting water and food. The general population is exposed to uranium primarily through food and water; the average daily intake of uranium from food ranges from 0.07 to 1.1 micrograms per day. The amount of uranium in air is usually very small; however, people who live near government facilities that made or tested nuclear weapons, or facilities that mine or process uranium ore or enrich uranium for reactor fuel, may have increased exposure to uranium. Houses or structures which are over uranium deposits (either natural or man-made slag deposits) may have an increased incidence of exposure to radon gas, a radioactive carcinogen. Uranium can enter the body when it is inhaled or swallowed, or under rare circumstances it may enter through cuts in the skin. Uranium does not absorb through the skin, and alpha particles released by uranium cannot penetrate the skin, so uranium that is outside the body is much less harmful than it would be if it were inhaled or swallowed. When uranium enters the body it can lead to kidney damage. Uranium itself is not a chemical carcinogen. Uranium mining carries the danger of airborne radioactive dust and the release of radioactive radon gas and its decay product (an added danger to the already dangerous activity of all hard rock mining). As a result, without proper ventilation, uranium miners have a dramatically increased risk of later development of lung cancer and other pulmonary diseases. There is also the possible danger of groundwater contamination with the toxic chemicals used in the separation of the uranium ore. ==See also== *Depleted uranium *Nuclear engineering *Nuclear fuel cycle *Nuclear physics *Nuclear reactor *Nuclear weapon ==References== *[http://pearl1.lanl.gov/periodic/elements/92.html Los Alamos National Laboratory's Chemistry Division: Periodic Table - Uranium] *[http://www.epa.gov/radiation/radionuclides/uranium.htm U.S. EPA: Radiation Information for Uranium] (some adapted public domain text) *''World Uranium Resources'', by Kenneth S. Deffeyes and Ian D. MacGregor, Scientific American, January, 1980, page 66. Argues that the supply of uranium is very large. * [http://www.ead.anl.gov/pub/doc/Depleted-Uranium.pdf Depleted Uranium Human Health Fact Sheet] from [http://www.ead.anl.gov/pub/doc/Cover-Intro-Linked.pdf Summary Fact Sheets for Selected Environmental Contaminants to Support Health Risk Analyses] by Argonne National Laboratory Environmental Assessment Division. * [http://www.ead.anl.gov/pub/doc/Uranium.pdf Uranium Human Health Fact Sheet], also from Argonne. == External links == * [http://www.webelements.com/webelements/elements/text/U/index.html WebElements.com - Uranium] (also used as a reference) * [http://environmentalchemistry.com/yogi/periodic/U.html EnvironmentalChemistry.com - Uranium] (also used as a reference) * [http://education.jlab.org/itselemental/ele092.html It's Elemental - Uranium] * [http://www.eia.doe.gov/fuelnuclear.html The US government provides lots of statistics and information relevant to the energy industry at ] * [http://www.neis.org/literature/Brochures/weapcon.htm Nuclear Power and Nuclear Weapons: Making the Connections] * [http://www.uic.com.au The Uranium Information Centre also has lots of information on uranium] * [http://www.antenna.nl/wise/uranium/umaps.html World Uranium deposit maps] * [http://www.world-nuclear.org/ushist.htm A thorough history of the element] Actinides Chemical elements Fuels

Uranium

Article changed over to new WikiProject Elements format by contributors to /Temp and User:Maveric149 11:18, 9 Jan 2004 (UTC) === Information Sources === Data for the table was obtained from the sources listed on the subject page and WikiProject Elements but was reformatted and converted into SI units. ---- Caution needs to be exercised in using the words fissile and fissionable. U-238 is fissionable, and fast fission of U-238 delivers much of the power in three-stage fission-fusion-fission weapons. But it is not fissile, and contributes little to the power of a thermal or near-thermal power reactor (the PWR and BWR are not fully thermalised, owing to the competing need to reduce neutron losses). U-235 and U-233 are fissile. User:Andrewa 17:01 20 Jun 2003 (UTC) ---- Shouldn't the atomic weight (somewhere around 210-250 or so) be mentioned in the article? User:Ilyanep 22:03, 2 Sep 2003 (UTC) :In the table now. --User:Maveric149 11:18, 9 Jan 2004 (UTC) ---- Question: The text says "Because uranium has such a long radioactive half-life (4.47x109 years for U-238), the total amount of it on Earth stays almost the same." However, this isn't strictly true -- the half-life implies that there's only about half the amount of uranium left of what existed when the Earth was created. --User:Guan 19:38, 29 Nov 2004 (UTC) :Hmm, yeah, that doesn't make much sense, I don't think. I've removed it -- better to omit something like that than to have it be wrong, I think. If someone knows better, please re-insert it. --User:Fastfission 04:59, 10 Apr 2005 (UTC) ---- This article should probably link to the articles on radiomentirc dating since there are a few radiometric dating methods than measure uranium isotopes--User:Petaholmes 01:23, 10 Apr 2005 (UTC) :I added a small line about it to the "applications" section. --User:Fastfission 04:59, 10 Apr 2005 (UTC) ---- anl.gov is down right now, so I can't check User:Fastfission's statement about the hazards of the decay products. However, U238 is an alpha emitter, the next two decay products are beta emitters, leaving U234. The alpha emitters are far more dangerous than beta's because alphas are typically very high energy, and for a given energy they are more damaging. U234 is an alpha, but the next decay product, Th230 has a half life of 80,000 years, so very little of it builds up in human timescales. As for U235, an alpha emitter, the next daughter is a beta emitter, and the next is Th 231 with a half life of 32,500 years, so it doesn't have time to build up. To summarize, the radiation of the parent uranium isotopes are far more hazardous than the daughters. User:Pstudier 02:15, 2005 Apr 15 (UTC) :From [http://www.ead.anl.gov/pub/doc/Depleted-Uranium.pdf ANL.gov]: :: Uranium is not considered a chemical carcinogen. A second concern is for uranium deposited in bone, which can lead to bone cancer as a result of the ionizing radiation associated with the radioactive decay products. Uranium has caused reproductive problems in laboratory animals and developmental problems in young animals, but it is not known if these problems exist for humans. :Additionally, the decay series of uranium-238 is not trivial; it is what is responsible for radon gas and its own hazardous daughter products. As I understand it. (I'm not trying to trump up its danger, I'm just trying to get it right). --User:Fastfission 16:21, 15 Apr 2005 (UTC) ::What I tried to say is that in a time scale of less than a few thousand years, the radioactivity of the daughters is insignificant because they don't have time to build up. You won't get significant radon from a piece of uranium in our lifetime. User:Pstudier 21:28, 2005 Apr 15 (UTC) :::So how does that accord with the information from Argonne and the fact that significant amounts of radon gas are emitted by uranium deposits? --User:Fastfission 22:33, 15 Apr 2005 (UTC) :::The Argonne information conflicts with what the Uranium Information Centre Ltd [http://www.uic.com.au/nip53.htm] and others have claimed. My guess is that it is only a minor hazard from the ionizing radiation of uranium. On the other hand, uranium deposits are generally much older than the few hundred thousand years it takes for the daughters to build up to equilibrium. Most obnoxious is radon because it is a gas that travels, and it deposits radioactive daughters Pb214 and Bi214 inside peoples lungs. Back before computer monitors were antistatic coated, one could wipe off the dust and detect Pb214 and the Bi214 with a Geiger counter, and watch it decay away. See [http://www.uic.com.au/neAp2.htm Nuclear Electricity] for a nice chart of the decay chains for U238 and U235. User:Pstudier 22:58, 2005 Apr 15 (UTC) ::::So who do we go with? Argonne National Lab, or an organization which is funded by uranium miners and whose articles seem to be bent on portraying uranium as harmless? A google search for "uranium bone ionizing radiation site:.gov" seems to imply that there are quite a lot of US government sites out there which report that uranium deposits itself into bone and can be cancer causing. From [http://www.ead.anl.gov/pub/doc/Depleted-Uranium.pdf ANL.GOV Depleted Uranium], we find that 30mg of uranium will cause ''Potential irreversible adverse effects''. The specific activity of natural uranium is 6.77E-7 Ci/gram. So this 30mg is about 20,000 pCi. From [http://www.ead.anl.gov/pub/doc/Uranium.pdf ANL.GOV Uranium], we find that the lifetime cancer risk for ingesting U238 is 7.5E-11 /pCi. I use U238 as the numbers are just a bit less for the other isotopes. So if we eat 30mg of uranium we will get sick but have a lifetime risk of cancer of 1.5E-6, or 1.5 in a million. I would say that the risk of getting cancer by ingesting uranium is insignificant compared to getting sick by chemical poisoning. User:Pstudier 00:54, 2005 Apr 16 (UTC) :I agree completely with that, but I think stating forcefully that it is not a carcinogen is simply incorrect, whether or not it is a very potent one. I'm aware, of course, that nearly every substance is a carcinogen to some degree, but I believe I once read (I can look this up) that the FDA defines (or maybe just defined) a chemical as a carcinogenic risk if it would cause cancer in 1 out of a million people, so 1.5 would be well within that. Anyway though, I can look that up. I don't remember the exact specification or whether it was in the past tense or not. In any event, I am again not trying to overstate the radioactive dangers of uranium (and I'm aware it is part of a more contentious debate over DU) because it is clear to me anyway that its toxicity dangers are far more likely to have an effect (and, in the case of DU weapons or nuclear weapons, the ''intended'' death-causing mechanisms are going to be much more effective than this sort of thing!), but I don't want to under-state it either.--User:Fastfission 03:08, 16 Apr 2005 (UTC) ::How about ''Uranium is a very weak carcinogen. Chemical toxicity, especially to the kidneys, is a greater health risk than radiological effects.'' Applies even more so to depleted uranium because it is about half as radioactive. User:Pstudier 23:16, 2005 Apr 16 (UTC)

Uranium

Uranium

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Words begining with Uranium:

Uranium
Uranium
Uranium
Uranium-234
Uranium-235
Uranium-238
Uranium-238
Uranium-series_dating
Uranium-thorium_dating
Uranium/Temp
Uranium/Temp
Uranium_235
Uranium_238
Uranium_city
Uranium_City,_Saskatchewan
Uranium_compounds
Uranium_enrichment
Uranium_fluoride
Uranium_Glass
Uranium_glass
Uranium_hexaflouride
Uranium_hexafluoride
Uranium_hexafluoride
Uranium_oxide