query: What is the atomic number of uranium?

title: Uranium

text: Uranium Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all isotopes of uranium are unstable, with half-lives varying between 159,200 years and 4.5 billion years. The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99%) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements. Its density is

title: Uranium ore

text: in the Athabasca Basin region of Canada. Uranium is generally used to generate nuclear fuel. Uranium deposits are generally classified based on host rocks, structural setting, and mineralogy of the deposit. The most widely used classification scheme was developed by the International Atomic Energy Agency (IAEA) and subdivides deposits into 15 categories. Uranium is a silvery-gray metallic weakly radioactive chemical element. It has the chemical symbol U and atomic number 92. The most common isotopes in natural uranium are U (99.27%) and U (0.72%). All uranium isotopes present in natural uranium are radioactive and fissionable, and U is fissile (will

title: Uranium

text: pyrophoric; small grains will ignite spontaneously in air at room temperature. Uranium metal is commonly handled with gloves as a sufficient precaution. Uranium concentrate is handled and contained so as to ensure that people do not inhale or ingest it. Uranium Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all isotopes of uranium are unstable, with half-lives varying between 159,200 years and 4.5

title: Atomic number

text: all known elements from hydrogen to uranium ("Z" = 92) were examined by his method. There were seven elements (with "Z" < 92) which were not found and therefore identified as still undiscovered, corresponding to atomic numbers 43, 61, 72, 75, 85, 87 and 91. From 1918 to 1947, all seven of these missing elements were discovered. By this time the first four transuranium elements had also been discovered, so that the periodic table was complete with no gaps as far as curium ("Z" = 96). In 1915 the reason for nuclear charge being quantized in units of "Z", which

title: Mass number

text: . This is technically redundant, as each element is defined by its atomic number, so it is often omitted. Different types of radioactive decay are characterized by their changes in mass number as well as atomic number, according to the radioactive displacement law of Fajans and Soddy. For example, uranium-238 usually decays by alpha decay, where the nucleus loses two neutrons and two protons in the form of an alpha particle. Thus the atomic number and the number of neutrons each decrease by 2 ("Z": 92→90, "N": 146→144), so that the mass number decreases by 4 ("A" = 238→234); the

title: World Uranium Hearing

text: World Uranium Hearing The World Uranium Hearing was held in Salzburg, Austria in September 1992. Anti-nuclear speakers from all continents, including indigenous speakers and scientists, testified to the health and environmental problems of uranium mining and processing, nuclear power, nuclear weapons, nuclear tests, and radioactive waste disposal. People who spoke at the 1992 Hearing include: Thomas Banyacya, Katsumi Furitsu, Manuel Pino and Floyd Red Crow Westerman. They said they were deeply dismayed by the atomic bombings of Hiroshima and Nagasaki and highlighted what they called the inherently destructive nature of all phases of the nuclear supply chain. They recalled the

title: Uranium hydride bomb

text: Uranium hydride bomb The uranium hydride bomb was a variant design of the atomic bomb first suggested by Robert Oppenheimer in 1939 and advocated and tested by Edward Teller. It used deuterium, an isotope of hydrogen, as a neutron moderator in a uranium-deuterium ceramic compact. Unlike all other fission-based weapon types, the concept relies on a chain reaction of slow nuclear fission (see neutron temperature). Bomb efficiency was adversely affected by the cooling of neutrons since the latter delays the reaction, as delineated by Rob Serber in his 1992 extension of the original Los Alamos Primer. The term hydride for

title: Atomic number

text: Atomic number The atomic number or proton number (symbol "Z") of a chemical element is the number of protons found in the nucleus of an atom. It is identical to the charge number of the nucleus. The atomic number uniquely identifies a chemical element. In an uncharged atom, the atomic number is also equal to the number of electrons. The sum of the atomic number "Z" and the number of neutrons, "N", gives the mass number "A" of an atom. Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes)

title: Atomic number

text: atomic numbers 1 to 118 have been observed. Synthesis of new elements is accomplished by bombarding target atoms of heavy elements with ions, such that the sum of the atomic numbers of the target and ion elements equals the atomic number of the element being created. In general, the half-life becomes shorter as atomic number increases, though an "island of stability" may exist for undiscovered isotopes with certain numbers of protons and neutrons. Atomic number The atomic number or proton number (symbol "Z") of a chemical element is the number of protons found in the nucleus of an atom. It

title: Uranium – Twisting the Dragon's Tail

text: shows how uranium turns into lead in the process of radioactive decay. The harmful effects of radiation from radium, which is produced during the decay of uranium, are discussed. Derek shows what the first atom bomb looked like. The episode concludes with the use of uranium as a nuclear weapon and the bombing of Hiroshima at the end of World War II. The use of uranium at the conclusion of World War II ushered in the atomic age. Uranium has since been utilized as a source of energy as well as in cancer treatment. Derek Muller visits Chernobyl and Fukushima,

title: Atomic number

text: neutral atom, which is "Z" (the atomic number). The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element's electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. Hence, it is the atomic number alone that determines the chemical properties of an element; and it is for this reason that an element can be defined as consisting of "any" mixture of atoms with a given atomic number. The quest for new elements is usually described using atomic numbers. As of 2010, all elements with

title: Atomic number

text: and the mass defect of nucleon binding is always small compared to the nucleon mass, the atomic mass of any atom, when expressed in unified atomic mass units (making a quantity called the "relative isotopic mass"), is within 1% of the whole number "A". Atoms with the same atomic number "Z" but different neutron numbers "N", and hence different atomic masses, are known as isotopes. A little more than three-quarters of naturally occurring elements exist as a mixture of isotopes (see monoisotopic elements), and the average isotopic mass of an isotopic mixture for an element (called the relative atomic mass)

title: Effective atomic number

text: interactions. For instance, lithium, atomic number 3, has two electrons in the 1s shell and one in the 2s shell. Because the two 1s electrons screen the protons to give an effective atomic number for the 2s electron close to 1, we can treat this 2s valence electron with a hydrogenic model. Mathematically, the effective atomic number Z can be calculated using methods known as "self-consistent field" calculations, but in simplified situations is just taken as the atomic number minus the number of electrons between the nucleus and the electron being considered. An alternative definition of the effective atomic number

title: Isotopes of uranium

text: Isotopes of uranium Uranium (U) is a naturally occurring radioactive element that has no stable isotopes but two primordial isotopes (uranium-238 and uranium-235) that have long half-lives and are found in appreciable quantity in the Earth's crust, along with the decay product uranium-234. The standard atomic weight of natural uranium is . Other isotopes such as uranium-232 have been produced in breeder reactors. Naturally occurring uranium is composed of three major isotopes, uranium-238 (99.2739–99.2752% natural abundance), uranium-235 (0.7198–0.7202%), and uranium-234 (0.0050–0.0059%). All three isotopes are radioactive, creating radioisotopes, with the most abundant and stable being uranium-238 with a half-life of

title: Effective atomic number

text: Effective atomic number Effective atomic number has two different meanings: one that is the effective nuclear charge of an atom, and one that calculates the average atomic number for a compound or mixture of materials. Both are abbreviated Z. The effective atomic number Z, (sometimes referred to as the effective nuclear charge) of an atom is the number of protons that an electron in the element effectively 'sees' due to screening by inner-shell electrons. It is a measure of the electrostatic interaction between the negatively charged electrons and positively charged protons in the atom. One can view the electrons in

title: Effective atomic number

text: is one quite different from that described above. The atomic number of a material exhibits a strong and fundamental relationship with the nature of radiation interactions within that medium. There are numerous mathematical descriptions of different interaction processes that are dependent on the atomic number, Z. When dealing with composite media (i.e. a bulk material composed of more than one element), one therefore encounters the difficulty of defining Z. An effective atomic number in this context is equivalent to the atomic number but is used for compounds (e.g. water) and mixtures of different materials (such as tissue and bone). This

title: Uranium-238

text: to control delayed neutrons, will potentially be able to use U as fuel once the reactor is started with LEU fuel. This design is still in the early stages of development. U is also used as a radiation shield – its alpha radiation is easily stopped by the non-radioactive casing of the shielding and the uranium's high atomic weight and high number of electrons are highly effective in absorbing gamma rays and x-rays. It is not as effective as ordinary water for stopping fast neutrons. Both metallic depleted uranium and depleted uranium dioxide are used for radiation shielding. Uranium is

title: Tummalapalle uranium mine

text: Work Index of the Tummalapalle uranium ore sample is 13.6 kWh/tonne and the mineralogical composition is as follows, Tummalapalle uranium mine The Tummalapalle Mine is a uranium mine in Tumalapalli village located in Kadapa of the Indian state of Andhra Pradesh. Results from research conducted by the Atomic Energy Commission of India in 2011 made the analysts conclude that this mine might have one of the largest reserves of uranium in the world. On 19 July 2011, Secretary of Department of Atomic Energy, Dr. S. Banerjee who is also the Chairman of the Atomic Energy Commission of India confirmed on

title: Atomic number

text: in a defined environment on Earth, determines the element's standard atomic weight. Historically, it was these atomic weights of elements (in comparison to hydrogen) that were the quantities measurable by chemists in the 19th century. The conventional symbol "Z" comes from the German word meaning "number", which, before the modern synthesis of ideas from chemistry and physics, merely denoted an element's numerical place in the periodic table, whose order is approximately, but not completely, consistent with the order of the elements by atomic weights. Only after 1915, with the suggestion and evidence that this "Z" number was also the nuclear

title: Uranium Corporation of India

text: Uranium Corporation of India Uranium Corporation of India (UCIL) is a centrally owned Public Sector Undertaking (PSU), under the Department of Atomic Energy for uranium mining and uranium processing. The corporation was founded in 1967 and is responsible for the mining and milling of uranium ore in India. The firm operates mines at Jadugora, Bhatin, Narwapahar, Turamdih and Banduhurang It is the first uranium mine of India which started its operations in 1967. This mine is located in the state of Jharkhand. Jadugoda process plant is located close to the mine which is used for the processing of the uranium

title: Atomic number

text: charge and a physical characteristic of atoms, did the word (and its English equivalent "atomic number") come into common use in this context. Loosely speaking, the existence or construction of a periodic table of elements creates an ordering of the elements, and so they can be numbered in order. Dmitri Mendeleev claimed that he arranged his first periodic tables (first published on March 6th, 1869) in order of atomic weight ("Atomgewicht"). However, in consideration of the elements' observed chemical properties, he changed the order slightly and placed tellurium (atomic weight 127.6) ahead of iodine (atomic weight 126.9). This placement is

title: Uranium ore

text: support a neutron-mediated chain reaction). Uranium, thorium, and potassium are the main elements contributing to natural terrestrial radioactivity. Uranium has the highest atomic weight of the naturally occurring elements and is approximately 70% denser than lead, but not as dense as tungsten, gold, platinum, iridium, or osmium. It is always found combined with other elements. Along with all elements having atomic weights higher than that of iron, it is only naturally formed in supernova explosions. The primary uranium ore mineral is uraninite (UO) (previously known as pitchblende). A range of other uranium minerals can be found in various deposits. These

title: Uranium Corporation of India

text: by the local tribals protesting against potential health effects. Uranium Corporation of India Uranium Corporation of India (UCIL) is a centrally owned Public Sector Undertaking (PSU), under the Department of Atomic Energy for uranium mining and uranium processing. The corporation was founded in 1967 and is responsible for the mining and milling of uranium ore in India. The firm operates mines at Jadugora, Bhatin, Narwapahar, Turamdih and Banduhurang It is the first uranium mine of India which started its operations in 1967. This mine is located in the state of Jharkhand. Jadugoda process plant is located close to the mine

title: Effective atomic number

text: possible to obtain a much more accurate single-valued Z by weighting against the spectrum of the source. The effective atomic number for electron interactions may be calculated with a similar approach; see for instance Taylor "et al." 2009 and Taylor 2011. The cross-section based approach for determining Z is obviously much more complicated than the simple power-law approach described above, and this is why freely-available software has been developed for such calculations (Taylor "et al." 2012). Effective atomic number Effective atomic number has two different meanings: one that is the effective nuclear charge of an atom, and one that calculates

title: Uranium mining

text: 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 region 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

title: Atomic number

text: was seen as containing 118 neutrons rather than 118 nuclear electrons, and its positive charge now was realized to come entirely from a content of 79 protons. After 1932, therefore, an element's atomic number "Z" was also realized to be identical to the proton number of its nuclei. The conventional symbol "Z" possibly comes from the German word (atomic number). However, prior to 1915, the word "Zahl" (simply "number") was used for an element's assigned number in the periodic table. Each element has a specific set of chemical properties as a consequence of the number of electrons present in the

title: Tummalapalle uranium mine

text: Tummalapalle uranium mine The Tummalapalle Mine is a uranium mine in Tumalapalli village located in Kadapa of the Indian state of Andhra Pradesh. Results from research conducted by the Atomic Energy Commission of India in 2011 made the analysts conclude that this mine might have one of the largest reserves of uranium in the world. On 19 July 2011, Secretary of Department of Atomic Energy, Dr. S. Banerjee who is also the Chairman of the Atomic Energy Commission of India confirmed on reserves of 49,000 tonnes and suggested that there could be even three times larger which would make Tummalapalle

title: Effective atomic number

text: comparing materials. In many textbooks and scientific publications, the following - simplistic and often dubious - sort of method is employed. One such proposed formula for the effective atomic number, Z, is as follows (Murty 1965): An example is that of water (HO), made up of two hydrogen atoms (Z=1) and one oxygen atom (Z=8), the total number of electrons is 1+1+8 = 10, so the fraction of electrons for the two hydrogens is (2/10) and for the one oxygen is (8/10). So the Z for water is: The effective atomic number is important for predicting how photons interact with

title: Uranium

text: radioactive isotope uranium-239. U decays by beta emission to neptunium-239, also a beta-emitter, that decays in its turn, within a few days into plutonium-239. Pu was used as fissile material in the first atomic bomb detonated in the "Trinity test" on 15 July 1945 in New Mexico. In nature, uranium is found as uranium-238 (99.2742%) and uranium-235 (0.7204%). Isotope separation concentrates (enriches) the fissionable uranium-235 for nuclear weapons and most nuclear power plants, except for gas cooled reactors and pressurised heavy water reactors. Most neutrons released by a fissioning atom of uranium-235 must impact other uranium-235 atoms to sustain the

title: Uranium

text: laser beam of precise energy to sever the bond between uranium-235 and fluorine. This leaves uranium-238 bonded to fluorine and allows uranium-235 metal to precipitate from the solution. An alternative laser method of enrichment is known as atomic vapor laser isotope separation (AVLIS) and employs visible tunable lasers such as dye lasers. Another method used is liquid thermal diffusion. A person can be exposed to uranium (or its radioactive daughters, such as radon) by inhaling dust in air or by ingesting contaminated water and food. The amount of uranium in air is usually very small; however, people who work in

title: Atomic number

text: consistent with the modern practice of ordering the elements by proton number, "Z", but that number was not known or suspected at the time. A simple numbering based on periodic table position was never entirely satisfactory, however. Besides the case of iodine and tellurium, later several other pairs of elements (such as argon and potassium, cobalt and nickel) were known to have nearly identical or reversed atomic weights, thus requiring their placement in the periodic table to be determined by their chemical properties. However the gradual identification of more and more chemically similar lanthanide elements, whose atomic number was not

title: Enriched uranium

text: Enriched uranium Enriched uranium is a type of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% U isotope, with U only constituting about 0.711% of its mass. U is the only nuclide existing in nature (in any appreciable amount) that is fissile with thermal neutrons. Enriched uranium is a critical component for both civil nuclear power generation and military nuclear weapons. The International Atomic Energy Agency attempts to monitor and control enriched uranium supplies and processes in its efforts to ensure nuclear power generation safety and curb

title: The Atomic Kid

text: marries "Blix" at the end, is the only female character in the film's opening credits and promotional posters, where she is billed as "Elaine Davis". At the time "The Atomic Kid" was being filmed, Devry/Davis was married to Mickey Rooney in real life. The Atomic Kid The Atomic Kid is a 1954 American black-and-white science fiction comedy film from Republic Pictures, produced by Maurice Duke and Mickey Rooney, directed by Leslie H. Martinson, that stars Mickey Rooney and Robert Strauss. While uranium prospector "Blix" Waterberry is in the desert, he wanders into an active atomic bomb test site and is

title: Uranium

text: by reaction with additional chlorine. All uranium chlorides react with water and air. Bromides and iodides of uranium are formed by direct reaction of, respectively, bromine and iodine with uranium or by adding to those element's acids. Known examples include: , , , and . Uranium oxyhalides are water-soluble and include , , , and . Stability of the oxyhalides decrease as the atomic weight of the component halide increases. Natural uranium consists of three major isotopes: uranium-238 (99.28% natural abundance), uranium-235 (0.71%), and uranium-234 (0.0054%). All three are radioactive, emitting alpha particles, with the exception that all three of

title: Uranium

text: description of this process of reactor control). As little as 15 lb (7 kg) of uranium-235 can be used to make an atomic bomb. The first nuclear bomb used in war, "Little Boy", relied on uranium fission, but the very first nuclear explosive (the "Gadget" used at Trinity) and the bomb that destroyed Nagasaki ("Fat Man") were both plutonium bombs. Uranium metal has three allotropic forms: The major application of uranium in the military sector is in high-density penetrators. This ammunition consists of depleted uranium (DU) alloyed with 1–2% other elements, such as titanium or molybdenum. At high impact speed,

title: Uranium mining and the Navajo people

text: The Navajo people refused to let any industry mine their land in the 1930s, when the appointed federal guardian to the Navajo Nation attempted to decide what mining should take place on their land. But pressure for mining increased in the postwar years, when the United States believed it had to develop resources to compete with the Soviet Union in the Cold War. In 1948, the United States Atomic Energy Commission (AEC) announced it would be the sole purchaser of any uranium mined in the United States, to cut off dependence on imported uranium. The AEC would not mine the

title: Atomic number

text: obvious, led to inconsistency and uncertainty in the periodic numbering of elements at least from lutetium (element 71) onward (hafnium was not known at this time). In 1911, Ernest Rutherford gave a model of the atom in which a central core held most of the atom's mass and a positive charge which, in units of the electron's charge, was to be approximately equal to half of the atom's atomic weight, expressed in numbers of hydrogen atoms. This central charge would thus be approximately half the atomic weight (though it was almost 25% different from the atomic number of gold ,

title: Atomic number

text: tube. The square root of the frequency of these photons increased from one target to the next in an arithmetic progression. This led to the conclusion (Moseley's law) that the atomic number does closely correspond (with an offset of one unit for K-lines, in Moseley's work) to the calculated electric charge of the nucleus, i.e. the element number "Z". Among other things, Moseley demonstrated that the lanthanide series (from lanthanum to lutetium inclusive) must have 15 members—no fewer and no more—which was far from obvious from the chemistry at that time. After Moseley's death in 1915, the atomic numbers of

title: Uranium

text: uranium in a broom closet before the improvement project; another had been keeping track of its stock of nuclear warheads using index cards kept in a shoe box. Along with all elements having atomic weights higher than that of iron, uranium is only naturally formed in supernovae. Primordial thorium and uranium are only produced in the r-process (rapid neutron capture), because the s-process (slow neutron capture) is too slow and cannot pass the gap of instability after bismuth. Besides the two extant primordial uranium isotopes, U and U, the r-process also produced significant quantities of U, which has a shorter

title: Atomic nucleus

text: from the electron cloud. Protons and neutrons are bound together to form a nucleus by the nuclear force. The diameter of the nucleus is in the range of () for hydrogen (the diameter of a single proton) to about for the heaviest atom uranium. These dimensions are much smaller than the diameter of the atom itself (nucleus + electron cloud), by a factor of about 26,634 (uranium atomic radius is about ()) to about 60,250 (hydrogen atomic radius is about ). The branch of physics concerned with the study and understanding of the atomic nucleus, including its composition and the

title: Uranium in the environment

text: 1971, thousands of homes and commercial buildings in the Colorado Plateau region were "found to contain anomalously high concentrations of radon, after being built on uranium tailings taken from piles under the authority of the Atomic Energy Commission". Depleted uranium (DU) is useful because of its very high density of 19.1 g/cm (68.4% denser than lead). Civilian uses include counterweights in aircraft, radiation shielding in medical radiation therapy and industrial radiography equipment, and containers used to transport radioactive materials. Military uses include defensive armor plating and armor-piercing projectiles. Uranium metal can disperse into the air and water, United Nations Environment

title: Uranium

text: short tons (53 metric tons) of uranium oxide, and six short tons (5.5 metric tons) of uranium metal, a majority of which was supplied by Westinghouse Lamp Plant in a makeshift production process. Two major types of atomic bombs were developed by the United States during World War II: a uranium-based device (codenamed "Little Boy") whose fissile material was highly enriched uranium, and a plutonium-based device (see Trinity test and "Fat Man") whose plutonium was derived from uranium-238. The uranium-based Little Boy device became the first nuclear weapon used in war when it was detonated over the Japanese city of

title: The Atomic Kid

text: The Atomic Kid The Atomic Kid is a 1954 American black-and-white science fiction comedy film from Republic Pictures, produced by Maurice Duke and Mickey Rooney, directed by Leslie H. Martinson, that stars Mickey Rooney and Robert Strauss. While uranium prospector "Blix" Waterberry is in the desert, he wanders into an active atomic bomb test site and is accidentally exposed to radiation from a direct overhead A-bomb blast. He miraculously survives, becoming radioactive, and in the process gaining special powers. He is then recruited for his powers by the FBI to help break up a spy ring. After helping to capture

title: Uranium mining and the Navajo people

text: risks in many communities. The Environmental Protection Agency estimates that there are 4000 mines with documented uranium production, and another 15,000 locations with uranium occurrences in 14 western states. Most are located in the Four Corners area and Wyoming. The Uranium Mill Tailings Radiation Control Act (1978) is a United States environmental law that amended the Atomic Energy Act of 1954 and authorized the Environmental Protection Agency to establish health and environmental standards for the stabilization, restoration, and disposal of uranium mill waste. Cleanup has continued to be difficult, and EPA administers several Superfund sites located in the Navajo Nation.

title: Climax Uranium Mill

text: Climax Uranium Mill Climax Uranium Mill is a decommissioned uranium mill near Grand Junction, CO. The mill, that processed vanadium as well as uranium, was incorporated May 11, 1950. It was constructed on city-owned property next to the Colorado River which was once the Grand Junction sugar beet mill. Climax Uranium Company gutted the former sugar beet mill, removing any remaining equipment and stabilizing weak walls, and began uranium and vanadium milling operations. The mill soon grew to be 12 buildings large and processed 2 million tons of ore, mostly for the United States Atomic Energy Commission. From the early

title: Peak uranium

text: for freshly mined uranium until very recently. Secondary supplies include military and commercial inventories, enriched uranium tails, reprocessed uranium and mixed oxide fuel. According to data from the International Atomic Energy Agency, world production of mined uranium has peaked twice in the past: once, circa 1960 in response to stockpiling for military use, and again in 1980, in response to stockpiling for use in commercial nuclear power. Up until about 1990, the mined uranium production was in excess of consumption by power plants. But since 1990, consumption by power plants has outstripped the uranium being mined; the deficit being made

title: Uranium mining

text: mining has been steadily increasing its share of the total, mainly due to Kazakhstan. Many different types of uranium deposits have been discovered and mined. There are mainly three types of uranium deposits including unconformity-type deposits, namely paleoplacer deposits and sandstone-type also known as roll front type deposits. Uranium deposits are classified into 15 categories according to their geological setting and the type of rock in which they are found. This geological classification system is determined by the International Atomic Energy Agency (IAEA). Uranium deposits in sedimentary rocks include those in sandstone (in Canada and the western US), Precambrian unconformities

title: Uranium ore

text: create internal pegmatites or hydrothermal systems into which uranium may dissolve. The International Atomic Energy Agency (IAEA) assigns uranium deposits to 15 main categories of deposit types, according to their geological setting and genesis of mineralization, arranged according to their approximate economic significance. The IAEA classification scheme works well, but is far from ideal, as it does not consider that similar processes may form many deposit types, yet in a different geological setting. The following table groups the above deposit types based on their environment of deposition. Unconformity-type uranium deposits host high grades relative to other uranium deposits and include

title: Uranium in the environment

text: in munitions is controversial because of questions about potential long-term health effects. Uranium is a naturally occurring element found in low levels within all rock, soil, and water. This is the highest-numbered element to be found naturally in significant quantities on earth. According to the United Nations Scientific Committee on the Effects of Atomic Radiation the normal concentration of uranium in soil is 300 μg/kg to 11.7 mg/kg. It is considered to be more plentiful than antimony, beryllium, cadmium, gold, mercury, silver, or tungsten and is about as abundant as tin, arsenic or molybdenum. It is found in many minerals

title: Atomic bombings of Hiroshima and Nagasaki

text: the development of an atomic bomb a theoretical possibility. Fears that a German atomic bomb project would develop atomic weapons first, especially among scientists who were refugees from Nazi Germany and other fascist countries, were expressed in the Einstein-Szilard letter. This prompted preliminary research in the United States in late 1939. Progress was slow until the arrival of the British MAUD Committee report in late 1941, which indicated that only 5 to 10 kilograms of isotopically enriched uranium-235 were needed for a bomb instead of tons of natural uranium and a neutron moderator like heavy water. The 1943 Quebec Agreement

title: Uranium mining

text: uranium concentrations than 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 atomic weapons program. Intensive exploration for uranium started after the end of World War II as a result of the military and civilian demand for uranium. There were three separate periods of uranium exploration or "booms." These were from 1956 to 1960, 1967 to 1971, and from 1976 to 1982. In the 20th century the United States was the world's

title: Peak uranium

text: for use in civilian nuclear reactors. As a result, starting in 1990, a significant portion of uranium nuclear power requirements were supplied by former weapons uranium, rather than newly mined uranium. In 2002, mined uranium supplied only 54 percent of nuclear power requirements. But as the supply of former weapons uranium has been used up, mining has increased, so that in 2012, mining provided 95 percent of reactor requirements, and the OCED Nuclear Energy Agency and the International Atomic Energy Agency projected that the gap in supply would be completely erased in 2013. Eleven countries, Germany, the Czech Republic, France,

title: Depleted uranium

text: those who have retained fragments of depleted uranium following combat related injury, it has been possible to detect elevated urinary uranium levels, but no kidney toxicity or other adverse health effects related to depleted uranium after a decade of follow-up." Pier Roberto Danesi, then-director of the International Atomic Energy Agency (IAEA) Seibersdorf +Laboratory, stated in 2002 that "There is a consensus now that DU does not represent a health threat". The IAEA reported in 2003 that, "based on credible scientific evidence, there is no proven link between DU exposure and increases in human cancers or other significant health or environmental

title: Uranium mining by country

text: could provide more than 170,000 tonnes of uranium, making it as the world's largest uranium mine. Production of the ore is slated to begin in 2012. The Department of Atomic Energy (DAE) recently discovered that the upcoming mine in Tumalapalli has close to 49,000 tonne of uranium reserves. This could just be a shot in the arm for India's nuclear power aspirations as it is three times the original estimate of the area's deposits. Jordan, the only Middle East country with confirmed uranium, is estimated to have around 140,000 tonnes in its uranium reserves plus a further 59,000 tonnes in

title: Atomic number

text: ), the single element from which Rutherford made his guess). Nevertheless, in spite of Rutherford's estimation that gold had a central charge of about 100 (but was element on the periodic table), a month after Rutherford's paper appeared, Antonius van den Broek first formally suggested that the central charge and number of electrons in an atom was "exactly" equal to its place in the periodic table (also known as element number, atomic number, and symbolized "Z"). This proved eventually to be the case. The experimental position improved dramatically after research by Henry Moseley in 1913. Moseley, after discussions with Bohr

title: Uranium mining in the United States

text: pods and rolls in the basal conglomerate of the Mauch Chunk Formation (Mississippian). Also present are the secondary uranium and uranium-vanadium minerals carnotite, tyuyamunite, liebigite, uranophane, and betauranophane. Uranium was discovered near Edgemont, South Dakota in 1951, quickly followed by mining. The uranium occurs in Cretaceous sandstones of the Inyan Kara group, where it outcrops along the southern edge of the Black Hills in Fall River County, South Dakota. Minerals in unoxidized sandstone are uraninite and coffinite; minerals in oxidized zones include carnotite and tyuyamunite. An airborne gamma radiation survey flown by the US Atomic Energy Commission in 1954 discovered

title: Uranium

text: in Paris by leaving a sample of a uranium salt, KUO(SO) (potassium uranyl sulfate), on top of an unexposed photographic plate in a drawer and noting that the plate had become "fogged". He determined that a form of invisible light or rays emitted by uranium had exposed the plate. A team led by Enrico Fermi in 1934 observed that bombarding uranium with neutrons produces the emission of beta rays (electrons or positrons from the elements produced; see beta particle). The fission products were at first mistaken for new elements with atomic numbers 93 and 94, which the Dean of the

title: Uranium mining

text: a measure designed to assist in the cleanup of 22 inactive ore-processing sites throughout the southwest. This also included constructing 19 disposal sites for the tailings, which contain a total of 40 million cubic yards of low-level radioactive material. The Environmental Protection Agency estimates that there are 4000 mines with documented uranium production, and another 15,000 locations with uranium occurrences in 14 western states, most found in the Four Corners area and Wyoming. The "Uranium Mill Tailings Radiation Control Act" is a United States environmental law that amended the Atomic Energy Act of 1954 and gave the Environmental Protection Agency

title: Honeymoon Uranium Mine

text: Honeymoon Uranium Mine The Honeymoon Mine is Australia's fourth uranium mine and Australia's second operating in-situ recovery mine and began production in 2011. The uranium deposit belongs to the palaeochannel type. Operations at Honeymoon were suspended in November 2013, following difficulties in reaching production targets, high costs and a falling uranium price. The project was placed in care and maintenance, then sold by JSC Atomenergoprom (a subsidiary of Rosatom State Atomic Energy Corporation) to Boss Resources and Wattle Mining in September 2015 for a sum of $9 million AUD. Boss Resources anticipates resuming production at the mine in 2019. The

title: Uranium carbide

text: Uranium carbide Uranium carbide, a carbide of uranium, is a hard refractory ceramic material. It comes in several stoichiometries (), such as uranium methanide (UC, CAS number 12070-09-6), uranium sesquicarbide (UC, CAS number 12076-62-9), and uranium acetylide (UC, CAS number 12071-33-9). Like uranium dioxide and some other uranium compounds, uranium carbide can be used as a nuclear fuel for nuclear reactors, usually in the form of pellets or tablets. Uranium carbide fuel was used in late designs of nuclear thermal rockets. Uranium carbide pellets are used as fuel kernels for the US version of pebble bed reactors; the German version

title: Jaduguda uranium mine

text: Corporation of India Limited (UCIL) expects mining activity to resume at Jaduguda in 2017. The Jaduguda mine produces up to 25% of the raw materials needed to fuel India’s nuclear reactors. The Jaduguda uranium mine is an underground mining mine located in the Purbi Singhbhum district of Jharkhand. The mine is located at least 640 meters below the earth’s surface and is accessible by a 5-meter diameter vertical shaft. A uranium purification plant is usually located closely to the mine as uranium ore is converted here to yellow cake. According to Department of Atomic Energy, the ore extracted from this

title: Uranium carbide

text: uses uranium dioxide instead. As nuclear fuel, uranium carbide can be used either on its own, or mixed with plutonium carbide (PuC and PuC). The mixture is also labeled as uranium-plutonium carbide (PuC U). Uranium carbide is also a popular target material for particle accelerators. Ammonia synthesis from nitrogen and hydrogen is sometimes accomplished in the presence of uranium carbide acting as a catalyst. Uranium carbide Uranium carbide, a carbide of uranium, is a hard refractory ceramic material. It comes in several stoichiometries (), such as uranium methanide (UC, CAS number 12070-09-6), uranium sesquicarbide (UC, CAS number 12076-62-9), and uranium

title: Effective atomic number

text: the other side; each electron will feel less than the attractive force of 26 protons because the other electron contributes a repelling force. The 4s electrons in Iron, which are furthest from the nucleus, feel an effective atomic number of only 5.43 because of the 25 electrons in between it and the nucleus screening the charge. Effective atomic numbers are useful not only in understanding why electrons further from the nucleus are so much more weakly bound than those closer to the nucleus, but also because they can tell us when to use simplified methods of calculating other properties and

title: Effective atomic number

text: electrons further away are screened from the nucleus by other electrons in between, and feel less electrostatic interaction as a result. The 1s electron of Iron (the closest one to the nucleus) sees an effective atomic number (number of protons) of 25. The reason why it is not 26 is because some of the electrons in the atom end up repelling the others, giving a net lower electrostatic interaction with the nucleus. One way of envisioning this effect is to imagine the 1s electron sitting on one side of the 26 protons in the nucleus, with another electron sitting on

title: Effective atomic number

text: for the photoelectric process which incorporates a ‘constant’ of 2.64 x 10, which is in fact not a constant but rather a function of the photon energy. A linear relationship between Z has been shown for a limited number of compounds for low-energy x-rays, but within the same publication it is shown that many compounds do not lie on the same trendline (Spiers "et al." 1946). As such, for polyenergetic photon sources (in particular, for applications such as radiotherapy), the effective atomic number varies significantly with energy (Taylor "et al." 2008). As shown by Taylor "et al." (2008), it is

title: Uranium mining in the United States

text: and the radium leached from these tailings contaminated thousands of miles of the Colorado River system. Between 1966 and 1971, thousands of homes and commercial buildings in the Colorado Plateau region were "found to contain anomalously high concentrations of radon, after being built on uranium tailings taken from piles under the authority of the Atomic Energy Commission". In 1950, the US Public Health service began a comprehensive study of uranium miners, leading to the first publication of a statistical correlation between cancer and uranium mining, released in 1962. The federal government eventually regulated the standard amount of radon in mines,

title: Depleted uranium

text: by his analysis nor by veteran medical statistics. Marshall also examined possible genetic effects due to radiation from depleted uranium. Chemical effects, including potential reproductive issues, associated with depleted uranium exposure were discussed in some detail in a subsequent journal paper. Elevated radiation levels consistent with very low level atmospheric depleted uranium contamination have been found in air samples taken by the UK Atomic Weapons Establishment at several monitoring sites in Britain. These elevated readings appear to coincide with Operation Anaconda in Afghanistan, and the Shock and Awe bombing campaign at the start of the Second Gulf War. On 4

title: Soviet atomic bomb project

text: research programs. In April 1942, Flyorov directed two classified letters to Stalin, warning him of the consequences of the development of atomic weapons: "...the results will be so overriding [that] it won't be necessary to determine who is to blame for the fact that this work has been neglected in our country." The second letter, by Flyorov and Konstantin Petrzhak, highly emphasized the importance of a "uranium bomb": "it is essential to manufacture a uranium bomb without a delay." Upon reading the Flyorov letters, Stalin immediately pulled Russian physicists from their respective military services and authorized an atomic bomb project,

title: Uranium-235

text: a nuclear explosion. The Little Boy gun type atomic bomb dropped on Hiroshima on August 6, 1945 was made of highly enriched uranium with a large tamper. The nominal spherical critical mass for an untampered U nuclear weapon is , a sphere 17.32 cm (6.8") in diameter. The material must be 85% or more of U and is known as weapons grade uranium, though for a crude, inefficient weapon 20% is sufficient (called "weapon(s)-usable"). Even lower enrichment can be used, but then the required critical mass rapidly increases. Use of a large tamper, implosion geometries, trigger tubes, polonium triggers, tritium

title: Uranium mining in Australia

text: domestic demand. The High Flux Australian Reactor at Lucas Heights, New South Wales operated from 1958 to 2007. The OPAL research reactor is currently in operation at Lucas Heights. Australian uranium is mined and sold only for electrical power generation or nuclear research, Almost all the uranium is exported under strict International Atomic Energy Agency safeguards. Uranium mining in Australia has been highly political, particularly for the Australian Labor Party(ALP) at both state and federal level. Development of projects has often been stymied by a succession of inquiries and the politicisation of the issuing of mining and export licences. The

title: Uranium

text: Hiroshima on 6 August 1945. Exploding with a yield equivalent to 12,500 tonnes of TNT, the blast and thermal wave of the bomb destroyed nearly 50,000 buildings and killed approximately 75,000 people (see Atomic bombings of Hiroshima and Nagasaki). Initially it was believed that uranium was relatively rare, and that nuclear proliferation could be avoided by simply buying up all known uranium stocks, but within a decade large deposits of it were discovered in many places around the world. The X-10 Graphite Reactor at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, formerly known as the Clinton Pile and

title: Atomic (Mogwai album)

text: Atomic (Mogwai album) Atomic is an original soundtrack album by Scottish post-rock band Mogwai, released on 1 April 2016 on Rock Action Records. The music was originally composed for Mark Cousins' documentary "Atomic, Living in Dread and Promise". The album features entirely instrumental music from start to finish. The song titles allude to atomic bombs such as Little Boy and Tzar Bomba as well as scientific or military objects and concepts connected with nuclear warfare such as SCRAM, Uranium-235 and Pripyat, the abandoned city near the Chernobyl Nuclear Power Plant in Ukraine. It is the first Mogwai album to not

title: Atomic spies

text: the fuel they needed. The Soviet scientists became frustrated with the difficulties of producing uranium fuel cheaply, and they found their industrial techniques for refinement lacking. The use of information stolen from the Manhattan Project eventually rectified the problem. Without such information, the problems the Soviet atomic team experienced would have taken many years to correct, affecting the production of a Soviet atomic weapon significantly. The missing link that explains the great leaps in the Soviet Union's atomic program is the espionage information and technical data that Moscow succeeded in obtaining from the Manhattan Project. Once the Soviets had learned

title: Atomic number

text: of the extra protons presumed present in all heavy nuclei. A helium nucleus was presumed to be composed of four protons plus two "nuclear electrons" (electrons bound inside the nucleus) to cancel two of the charges. At the other end of the periodic table, a nucleus of gold with a mass 197 times that of hydrogen, was thought to contain 118 nuclear electrons in the nucleus to give it a residual charge of + 79, consistent with its atomic number. All consideration of nuclear electrons ended with James Chadwick's discovery of the neutron in 1932. An atom of gold now

title: Uranium mining by country

text: producer in history behind the USA and Canada. Minor production still takes place at the Königstein mine southeast of Dresden from cleaning of mine water. This production has been 38 t of uranium in 2007. In Hungary, uranium mining began in the 1950s around Pécs to supply the country's first atomic plant in Paks. A whole district was built for the mining industry on the outskirt of Pécs, for which the name Uránváros (Uranium city) was given. After the fall of communism, uranium mining was gradually given up because of the high production costs. That caused serious economic problems and

title: Atomic Minerals Directorate for Exploration and Research

text: 1998 it underwent the latest name change as 'Atomic Minerals Directorate for Exploration and Research' to assert its status as a premier geological exploration and research organisation. Professor D.N. Wadia, FRS, a doyen among Indian geologists guided the organisation from its inception to 1970 as Geological Adviser to Government of India. The prime mandate of Atomic Minerals Directorate for Exploration and Research is to identify and evaluate uranium resources required for the successful implementation of Atomic Energy programme of the country. AMD over the past five decades has been instrumental in locating Uranium resources in Singhbhum Shear Zone, Jharkhand; KPM

title: Uranium mining in Namibia

text: 1980. Jacob "et al." reported in the mid-1980s that the country's uranium mineralization was concentrated in the central zone of the Pan-African Damaran Orogen. In 1999, the International Atomic Energy Agency reported that the only operating mine in the county was the Rössing uranium mine, the largest uranium mine in the world. However, there has been a resurgence in the industry since 2003, and in 2008 uranium mine production in the whole of Africa increased by 16% compared to the previous year. Primary mines have since been opened, including Valencia, Ida Dome, and Goanikontes, as well as two secondary mines,

title: Peak uranium

text: contract to contract and often from delivery to delivery within the term of a contract. Since the number of companies mining uranium is small, the number of available contracts is also small. Supplies are running short due to flooding of two of the world's largest mines and a dwindling amount of uranium salvaged from nuclear warheads being removed from service. While demand for the metal has been steady for years, the price of uranium is expected to surge as a host of new nuclear plants come online. Rising uranium price entices draws investment into new uranium mining projects. Mining companies

title: Uranium Mill Tailings Radiation Control Act

text: in 1959, in which the Atomic Energy Commission gave regulatory authority of certain nuclear materials to states. It was unclear how much regulatory power Agreement states had, and as a result these states took little regulatory action. Sites that were owned by the federal government, the NRC, or Agreement states were ineligible for remedial action under the UMTRCA, as they were instead the responsibility of the government agencies or states who owned them. Uranium Mill Tailings Radiation Control Act The Uranium Mill Tailings Radiation Control Act (1978) is a United States environmental law that amended the Atomic Energy Act of

title: Tummalapalle uranium mine

text: which commenced in August 2008, was inaugurated by Srikumar Banerjee on 7 July 2011. The construction works for the first phase of the uranium purification plant are in their final stages and the plant was expected to begin production by the end of 2011. Phase one of the uranium purification plant has a capacity to treat 3,000 tonnes of ore per day. The Bhabha Atomic Research Centre (BARC) has developed an innovative, economically viable process for the recovery of low-grade uranium (less than 0.2%) from the Tummalapalle ore mine. As illustrated by Dr. A. K. Suri, Director of Materials Group,

title: Climax Uranium Mill

text: 1950s to 1966, Climax donated approximately 300,000 tons of radioactive uranium tailings to the city of Grand Junction for use as a construction material. The tailings were used in sewer and road construction. In 1972, Congress gave the Atomic Energy Commission authority to cooperate with Grand Junction in a cleanup operation, with the federal government covering 75% of the project's cost. The mill was decommissioned in 1970 under the US Department of Energy's Uranium Mill Tailings Remedial Action project. The mill site was designated for environmental remediation by the Uranium Mill Tailings Radiation Control Act in 1978. The Nuclear Regulatory

title: Niger uranium forgeries

text: Rome." In 2008, the United States facilitated shipping yellowcake (refined uranium ore) out of Iraq. This yellowcake had been stockpiled prior to the first Gulf War, and was declared to the International Atomic Energy Agency and under IAEA safeguards. More than 550 tons of yellowcake was removed from Iraq and eventually shipped to Canada. Background Documents and those who relied on them Joseph Wilson and Valarie Plame United States Administration statements, speeches, plans Legislative investigations Niger uranium forgeries The Niger uranium forgeries were forged documents initially released in 2001 by SISMI (Italian military intelligence), which seem to depict an attempt

title: Effective atomic number

text: a substance, as certain types of photon interactions depend on the atomic number. The exact formula, as well as the exponent 2.94, can depend on the energy range being used. As such, readers are reminded that this approach is of very limited applicability and may be quite misleading. This 'power law' method, while commonly employed, is of questionable appropriateness in contemporary scientific applications within the context of radiation interactions in heterogeneous media. This approach dates back to the late 1930s when photon sources were restricted to low-energy x-ray units (Mayneord 1937). The exponent of 2.94 relates to an empirical formula

title: Effective atomic number

text: is of most interest in terms of radiation interaction with composite materials. For bulk interaction properties, it can be useful to define an effective atomic number for a composite medium and, depending on the context, this may be done in different ways. Such methods include (i) a simple mass-weighted average, (ii) a power-law type method with some (very approximate) relationship to radiation interaction properties or (iii) methods involving calculation based on interaction cross sections. The latter is the most accurate approach (Taylor 2012), and the other more simplified approaches are often inaccurate even when used in a relative fashion for

title: Uranium-234

text: which makes the radioactivity of depleted uranium about one-half of that of natural uranium. Natural uranium has an "equilibrium" concentration of U-234 at the point where an equal number of decays of U-238 and U-234 will occur. Uranium-234 Uranium-234 is an isotope of uranium. In natural uranium and in uranium ore, U-234 occurs as an indirect decay product of uranium-238, but it makes up only 0.0055% (55 parts per million) of the raw uranium because its half-life of just 245,500 years is only about 1/18,000 as long as that of U-238. The primary path of production of U-234 via nuclear

title: Atomic spies

text: a different isotope-extraction method. The Allied program decided to use gas-phase extraction to obtain the pure uranium necessary for an atomic detonation. Using this method, it took large quantities of uranium ore and other rare materials such as graphite to successfully purify the U-235 isotope. The quantities required for the development were also beyond the scope and purview of the Soviet program. The Soviet Union did not have natural uranium-ore mines at the start of the nuclear arms race. A lack of materials made it very difficult to conduct novel research or to map out a clear pathway to achieving

title: Peak uranium

text: uranium demands any longer and must import uranium from other countries. Thirteen countries have hit peak and exhausted their uranium resources. In a similar manner to every other natural metal resource, for every tenfold increase in the cost per kilogram of uranium, there is a three-hundredfold increase in available lower quality ores that would then become economical. The world demand for uranium in 1996 was over per year, and that number had been expected to increase to between and per year by 2025 due to the number of new nuclear power plants coming on line. However following the shutdown of

title: Effective atomic number

text: an atom as being 'stacked' by energy outside the nucleus; the lowest energy electrons (such as the 1s and 2s electrons) occupy the space closest to the nucleus, and electrons of higher energy are located further from the nucleus. The binding energy of an electron, or the energy needed to remove the electron from the atom, is a function of the electrostatic interaction between the negatively charged electrons and the positively charged nucleus. In Iron, atomic number 26, for instance, the nucleus contains 26 protons. The electrons that are closest to the nucleus will 'see' nearly all of them. However,

title: Uranium mining and the Navajo people

text: less than miners from off-reservation, well below minimum wage. Until radon exposure safety standards were imposed by the Secretary of Labor Willard Wirtz over the objections of the Atomic Energy Commission and the uranium mining industry in June, 1967, mines lacked ventilation, exposing workers to radon. Widows of mine workers met to discuss their grief; they started a grassroots movement that eventually reached the Congressional floor. The Church Rock uranium mill spill raised claims that race was a factor in the federal government's paying little attention to the disaster: Many residents of the Navajo Nation have anxiety and concerns about

title: Soviet atomic bomb project

text: theory, alongside Isaak Pomeranchuk. Despite early and accelerated efforts, it was reported by historians that efforts on building a bomb using weapon-grade uranium seemed hopeless to Russian scientists. Igor Kurchatov had harboured doubts working towards the uranium bomb, made progress on a bomb using weapon-grade plutonium after British data was provided by the NKVD. The situation dramatically changed when the Soviet Union learned of the atomic bombings of Hiroshima and Nagasaki in 1945, which eventually led to the unilateral surrender of Japan to the United States, ending the war in Asia. Immediately after the atomic bombing, the Soviet Politburo took

title: Bulletin of the Atomic Scientists

text: legal and ethical considerations. Once the Soviet Union developed atomic weapons, the concern surrounding the world's destruction was a great fear of the scientists working on the "Bulletin." The proximity of nuclear devastation was a popular interest and, as a result, "Bulletin" co-editor Hyman Goldsmith asked landscape artist Martyl Langsdorf to create a cover for the June 1947 magazine. Langsdorf, who was married to Manhattan Project physicist Alexander Langsdorf, first considered using the symbol for uranium but then realized that a clock would better convey "a sense of urgency." The resultant Doomsday Clock, which only has bullets labeling the numbers

title: Uranium–uranium dating

text: Uranium–uranium dating Uranium–uranium dating is a radiometric dating technique which compares two isotopes of uranium (U) in a sample: uranium-234 (U) and uranium-238 (U). It is one of several radiometric dating techniques exploiting the uranium radioactive decay series, in which U undergoes 14 alpha and beta decay events on the way to the stable isotope Pb. Other dating techniques using this decay series include uranium–thorium dating and uranium–lead dating. U, with a half-life of about 4.5 billion years, decays to U through emission of an alpha particle to thorium-234 (Th), which is comparatively unstable with a half-life of just 24

title: Uranium mining in Arizona

text: For some years starting in 1980, the Twin Buttes copper mine in Pima County recovered uranium as a byproduct from leach solutions recovering copper from waste material. After the end of World War II, the United States encouraged uranium mining to build nuclear weapons stockpiles. Large uranium deposits were found on and near the Navajo Reservation, and mining companies hired many Navajos. Disregarding the health risks of radiation exposure, the private companies and the United States Atomic Energy Commission failed to inform the Navajo workers about the dangers and to regulate the mining to minimize contamination. As more data was

title: Isotopes of uranium

text: of natural uranium is uranium-238, which has a half-life of 1.41×10 seconds (4.468×10 years, or 4.468 billion years). Depleted uranium has an even higher concentration of the U-238 isotope, and even low-enriched uranium (LEU), while having a higher proportion of the uranium-235 isotope (in comparison to depleted uranium), is still mostly 238U. Reprocessed uranium is also mainly U-238, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as uranium-234, uranium-233, and uranium-232 Uranium-239 is an isotope of uranium. It is usually produced by exposing U to

title: Peak uranium

text: (46,403 tonnes/yr), this is not enough to stave off peak uranium. Thorium is an alternate fuel cycle to uranium. Thorium is three times more plentiful than uranium. Thorium-232 is in itself not fissile, but fertile. It can be made into fissile uranium-233 in a breeder reactor. In turn, the uranium-233 can be fissioned, with the advantage that smaller amounts of transuranics are produced by neutron capture, compared to uranium-235 and especially compared to plutonium-239. Despite the thorium fuel cycle having a number of attractive features, development on a large scale can run into difficulties: Advocates for liquid core and molten

title: Atomic broadcast

text: is relatively easy if it can be assumed that computers will not fail. For example, if there are no failures, atomic broadcast can be achieved simply by having all participants communicate with one "leader" which determines the order of the messages, with the other participants following the leader. However, real computers are faulty; they fail and recover from failure at unpredictable, possibly inopportune, times. For example, in the follow-the-leader algorithm, what if the leader fails at the wrong time? In such an environment achieving atomic broadcasts is difficult. A number of protocols have been proposed for performing atomic broadcast, under

title: Depleted uranium

text: transporting radioactive materials. Military uses include armor plating and armor-piercing projectiles. Most depleted uranium arises as a by-product of the production of enriched uranium for use as fuel in nuclear reactors and in the manufacture of nuclear weapons. Enrichment processes generate uranium with a higher-than-natural concentration of lower-mass-number uranium isotopes (in particular U-235, which is the uranium isotope supporting the fission chain reaction) with the bulk of the feed ending up as depleted uranium, in some cases with mass fractions of U-235 and U-234 less than a third of those in natural uranium. Since U-238 has a much longer half-life

title: Uranium–uranium dating

text: between the ranges of Th/U (accurate up to ca. 450,000 years) and U–Pb dating (accurate up to the age of the solar system, but problematic on samples younger than about 2 million years). Uranium–uranium dating Uranium–uranium dating is a radiometric dating technique which compares two isotopes of uranium (U) in a sample: uranium-234 (U) and uranium-238 (U). It is one of several radiometric dating techniques exploiting the uranium radioactive decay series, in which U undergoes 14 alpha and beta decay events on the way to the stable isotope Pb. Other dating techniques using this decay series include uranium–thorium dating and

title: The Atomic Cafe

text: of the media and public. Though the topic of atomic holocaust is a grave matter, "The Atomic Cafe" approaches it with black humor. Much of the humor derives from the modern audience's reaction to the old training films, such as the "Duck and Cover" film shown in schools. A quote to illustrate what can be perceived as black humor, culled from the movie: "Viewed from a safe distance, the atomic bomb is one of the most beautiful sights ever seen by man," a U.S. Army training film declares. "The Atomic Cafe" was released at the height of nostalgia and cynicism

text: Uranium Mill Tailings Radiation Control Act The Uranium Mill Tailings Radiation Control Act (1978) is a United States environmental law that amended the Atomic Energy Act of 1954 and authorized the Environmental Protection Agency to establish health and environmental standards for the stabilization, restoration, and disposal of uranium mill waste. Title 1 of the Act required the EPA to set environmental protection standards consistent with the Resource Conservation and Recovery Act, including groundwater protection limits; the Department of Energy to implement EPA standards and provide perpetual care for some sites; and the Nuclear Regulatory Commission to review cleanups and license