Uranium

qas: question: What kind of uranium is sometimes used to shield radioactive materials in containers?
answers: text: Depleted

question: What is a strong source of radiation that is blocked by depleted uranium?
answers: text: radium

question: How is depleted uranium used in missile re-entry vehicles?
answers: text: ballast

question: What trait causes depleted uranium to be used in gyroscopic compasses?
answers: text: high density

question: What type of alpha emitter is uranium?
answers: text: weak

question: What kind of uranium is always used to shield radioactive materials in containers?

question: What is a weak source of radiation that is blocked by depleted uranium?

question: How is depleted uranium not used in missile re-entry vehicles?

question: What trait causes depleted uranium not to be used in gyroscopic compasses?

question: What type of beta emitter is uranium?
context: Depleted uranium is also used as a shielding material in some containers used to store and transport radioactive materials. While the metal itself is radioactive, its high density makes it more effective than lead in halting radiation from strong sources such as radium. Other uses of depleted uranium include counterweights for aircraft control surfaces, as ballast for missile re-entry vehicles and as a shielding material. Due to its high density, this material is found in inertial guidance systems and in gyroscopic compasses. Depleted uranium is preferred over similarly dense metals due to its ability to be easily machined and cast as well as its relatively low cost. The main risk of exposure to depleted uranium is chemical poisoning by uranium oxide rather than radioactivity (uranium being only a weak alpha emitter).

qas: question: What is another term for uranium ore?
answers: text: pitchblende

question: Who isolated radium in uranium ore?
answers: text: Marie Curie

question: In what types of paints was radium first used?
answers: text: glow-in-the-dark

question: What devices were painted with radium paint?
answers: text: clock and aircraft dials

question: Along with red, blue, black, yellow and green, what was a notable color of uranium tile glaze?
answers: text: mauve

question: What isn't another term for uranium ore?

question: Who isolated radium in uranium core?

question: In what types of paints was radium last used?

question: What devices weren't painted with radium paint?

question: Along with red, blue, black, yellow and green, what wasn't a notable color of uranium tile glaze?
context: The discovery and isolation of radium in uranium ore (pitchblende) by Marie Curie sparked the development of uranium mining to extract the radium, which was used to make glow-in-the-dark paints for clock and aircraft dials. This left a prodigious quantity of uranium as a waste product, since it takes three tonnes of uranium to extract one gram of radium. This waste product was diverted to the glazing industry, making uranium glazes very inexpensive and abundant. Besides the pottery glazes, uranium tile glazes accounted for the bulk of the use, including common bathroom and kitchen tiles which can be produced in green, yellow, mauve, black, blue, red and other colors.

qas: question: What was the world's first artificial nuclear reactor?
answers: text: Enrico Fermi's Chicago Pile

question: In what state is the X-10 Graphite Reactor located?
answers: text: Tennessee

question: Along with the X-10 Pile, what was the X-10 Graphite Reactor previously known as?
answers: text: the Clinton Pile

question: In what state is Argonne National Laboratory's Experimental Breeder Reactor I located?
answers: text: Idaho

question: On what date did Breeder Reactor I first make electricity?
answers: text: 20 December 1951

question: What was the world's last artificial nuclear reactor?

question: In what state is the X-01 Graphite Reactor located?

question: Along with the X-10 Pile, what was the X-10 Graphite Reactor never known as?

question: In what state is Argonne National Laboratory's Experimental Breeder Reactor II located?

question: On what date did Breeder Reactor II first make electricity?
context: The X-10 Graphite Reactor at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, formerly known as the Clinton Pile and X-10 Pile, was the world's second artificial nuclear reactor (after Enrico Fermi's Chicago Pile) and was the first reactor designed and built for continuous operation. Argonne National Laboratory's Experimental Breeder Reactor I, located at the Atomic Energy Commission's National Reactor Testing Station near Arco, Idaho, became the first nuclear reactor to create electricity on 20 December 1951. Initially, four 150-watt light bulbs were lit by the reactor, but improvements eventually enabled it to power the whole facility (later, the town of Arco became the first in the world to have all its electricity come from nuclear power generated by BORAX-III, another reactor designed and operated by Argonne National Laboratory). The world's first commercial scale nuclear power station, Obninsk in the Soviet Union, began generation with its reactor AM-1 on 27 June 1954. Other early nuclear power plants were Calder Hall in England, which began generation on 17 October 1956, and the Shippingport Atomic Power Station in Pennsylvania, which began on 26 May 1958. Nuclear power was used for the first time for propulsion by a submarine, the USS Nautilus, in 1954.

qas: question: Where does uranium rank among elements in terms of its abundance in the Earth's crust?
answers: text: 51st

question: Where is uranium naturally formed?
answers: text: in supernovae

question: Along with potassium-40 and uranium, the decay of what element is a primary heat source driving plate tectonics?
answers: text: thorium

question: In what state is the Earth's outer core?
answers: text: liquid

question: Where does uranium rank among elements in terms of its abundance in the Earth's atmosphere?

question: Where is uranium unnaturally formed?

question: Along with potassium-40 and uranium, the decay of what element is a primary cooling source driving plate tectonics?

question: In what state is the Earth's inner core?

question: In what state is the Earth's middle core?
context: Uranium is a naturally occurring element that can be found in low levels within all rock, soil, and water. Uranium is the 51st element in order of abundance in the Earth's crust. Uranium is also the highest-numbered element to be found naturally in significant quantities on Earth and is almost always found combined with other elements. Along with all elements having atomic weights higher than that of iron, it is only naturally formed in supernovae. The decay of uranium, thorium, and potassium-40 in the Earth's mantle is thought to be the main source of heat that keeps the outer core liquid and drives mantle convection, which in turn drives plate tectonics.

qas: question: What isotope of uranium was the first to be found fissile?
answers: text: 235

question: How many nuclei does uranium-235 usually divide into when bombarded with slow neutrons?
answers: text: two

question: When a nuclear chain reaction in uranium-235 doesn't result in a burst of heat, what does it result in?
answers: text: an explosion

question: What is used to slow a chain reaction in a nuclear reactor?
answers: text: neutron poison

question: What does a neutron poison absorb?
answers: text: free neutrons

question: What isotope of uranium was the last to be found fissile?

question: How many nuclei does uranium-245 usually divide into when bombarded with slow neutrons?

question: When a nuclear chain reaction in uranium-245 doesn't result in a burst of heat, what does it result in?

question: What is used to speed a chain reaction in a nuclear reactor?

question: What does a neutron poison give off?
context: Uranium-235 was the first isotope that was found to be fissile. Other naturally occurring isotopes are fissionable, but not fissile. On bombardment with slow neutrons, its uranium-235 isotope will most of the time divide into two smaller nuclei, releasing nuclear binding energy and more neutrons. If too many of these neutrons are absorbed by other uranium-235 nuclei, a nuclear chain reaction occurs that results in a burst of heat or (in special circumstances) an explosion. In a nuclear reactor, such a chain reaction is slowed and controlled by a neutron poison, absorbing some of the free neutrons. Such neutron absorbent materials are often part of reactor control rods (see nuclear reactor physics for a description of this process of reactor control).

qas: question: What type of complexes does uranium(VI) form in nature?
answers: text: carbonate

question: The presence of what substance at alkaline pH makes it difficult to precipitate uranium as phosphate?
answers: text: carbonate

question: What is BSAR-1 a strain of?
answers: text: Sphingomonas sp.

question: What type of complexes does uranium(V) form in nature?

question: What type of complexes does uranium(VI) not form in nature?

question: The presence of what substance at alkaline pH makes it easy to precipitate uranium as phosphate?

question: What is BSAR-2 a strain of?

question: What is BSAR-1 not a strain of?
context: In nature, uranium(VI) forms highly soluble carbonate complexes at alkaline pH. This leads to an increase in mobility and availability of uranium to groundwater and soil from nuclear wastes which leads to health hazards. However, it is difficult to precipitate uranium as phosphate in the presence of excess carbonate at alkaline pH. A Sphingomonas sp. strain BSAR-1 has been found to express a high activity alkaline phosphatase (PhoK) that has been applied for bioprecipitation of uranium as uranyl phosphate species from alkaline solutions. The precipitation ability was enhanced by overexpressing PhoK protein in E. coli.

qas: question: How much economically viable uranium is there in ore reserves, in millions of tonnes?
answers: text: 5.5

question: How many millions of tonnes are uranium are regarded as mineral resources?
answers: text: 35

question: What was the price of uranium per pound as of May 2003?
answers: text: $10

question: In 2005, how much money was spent on uranium exploration?
answers: text: US$200 million

question: How much money was spent to explore for uranium in 2006?
answers: text: $774 million

question: How much economically viable uranium is there in ore reserves, in billions of tonnes?

question: How many billions of tonnes are uranium are regarded as mineral resources?

question: What was the price of uranium per kilo as of May 2003?

question: In 2015, how much money was spent on uranium exploration?

question: How much money was spent to explore for uranium in 2016?
context: It is estimated that 5.5 million tonnes of uranium exists in ore reserves that are economically viable at US$59 per lb of uranium, while 35 million tonnes are classed as mineral resources (reasonable prospects for eventual economic extraction). Prices went from about $10/lb in May 2003 to $138/lb in July 2007. This has caused a big increase in spending on exploration, with US$200 million being spent worldwide in 2005, a 54% increase on the previous year. This trend continued through 2006, when expenditure on exploration rocketed to over $774 million, an increase of over 250% compared to 2004. The OECD Nuclear Energy Agency said exploration figures for 2007 would likely match those for 2006.

qas: question: When was it observed that bombarding uranium with neutrons results in beta ray emission?
answers: text: 1934

question: Who led the team that discovered that bombarding uranium with neutrons created beta ray emissions?
answers: text: Enrico Fermi

question: What was the name given by Corbino to the incorrectly designated atomic number 94?
answers: text: hesperium

question: What was the job title of Orso Mario Corbino?
answers: text: Dean of the Faculty of Rome

question: Who was the aunt of Otto Robert Frisch?
answers: text: Lise Meitner

question: When was it observed that bombarding uranium with neutrons results in gamma ray emission?

question: Who led the team that discovered that bombarding uranium with neutrons created gamma ray emissions?

question: What was the name given by Corbino to the incorrectly designated atomic number 194?

question: What wasn't the job title of Orso Mario Corbino?

question: Who was the uncle of Otto Robert Frisch?
context: 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 of atomic numbers 93 and 94, which the Dean of the Faculty of Rome, Orso Mario Corbino, christened ausonium and hesperium, respectively. The experiments leading to the discovery of uranium's ability to fission (break apart) into lighter elements and release binding energy were conducted by Otto Hahn and Fritz Strassmann in Hahn's laboratory in Berlin. Lise Meitner and her nephew, the physicist Otto Robert Frisch, published the physical explanation in February 1939 and named the process "nuclear fission". Soon after, Fermi hypothesized that the fission of uranium might release enough neutrons to sustain a fission reaction. Confirmation of this hypothesis came in 1939, and later work found that on average about 2.5 neutrons are released by each fission of the rare uranium isotope uranium-235. Further work found that the far more common uranium-238 isotope can be transmuted into plutonium, which, like uranium-235, is also fissile by thermal neutrons. These discoveries led numerous countries to begin working on the development of nuclear weapons and nuclear power.

qas: question: In what medium does the Pourbaix diagram change when carbonate anions interact with uranium(VI)?
answers: text: carbonate containing solution

question: What notable carbonates are often water soluble?
answers: text: uranium

question: What does a uranium(VI) cation form when it binds to two terminal oxides and three or more carbonates?
answers: text: anionic complexes

question: In what medium does the Pourbaix diagram change when carbonate anions interact with uranium(VII)?

question: In what medium does the Pourbaix diagram change when carbonite anions interact with uranium(VI)?

question: What notable carbonates are unoften water soluble?

question: What does a uranium(VI) cation form when it binds to two terminal dioxides and three or more carbonates?

question: What does a uranium(VII) cation form when it binds to two terminal oxides and three or more carbonates?
context: The interactions of carbonate anions with uranium(VI) cause the Pourbaix diagram to change greatly when the medium is changed from water to a carbonate containing solution. While the vast majority of carbonates are insoluble in water (students are often taught that all carbonates other than those of alkali metals are insoluble in water), uranium carbonates are often soluble in water. This is because a U(VI) cation is able to bind two terminal oxides and three or more carbonates to form anionic complexes.

qas: question: Along with arsenic, what metal is roughly as abundant as uranium?
answers: text: molybdenum

question: Along with silver, mercury, tin and cadmium, what metal is uranium more plentiful than?
answers: text: antimony

question: What is the most prevalent uranium ore?
answers: text: uraninite

question: What mineral sometimes contains uranium?
answers: text: lignite

question: What types of rocks sometimes contain uranium?
answers: text: phosphate

question: Along with arsenic, what metal is less abundant as uranium?

question: Along with silver, mercury, tin and cadmium, what metal is uranium less plentiful than?

question: What is the least prevalent uranium ore?

question: What mineral always contains uranium?

question: What types of rocks never contain uranium?
context: Uranium is more plentiful than antimony, tin, cadmium, mercury, or silver, and it is about as abundant as arsenic or molybdenum. Uranium is found in hundreds of minerals, including uraninite (the most common uranium ore), carnotite, 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 sources with as little as 0.1% uranium).

qas: question: What is the least prevalent major isotope of natural uranium?
answers: text: uranium-234

question: What is the natural abundance of uranium-235?
answers: text: 0.71%

question: What isotope of uranium is formed when 238U experiences spontaneous fission?
answers: text: uranium-239

question: When uranium isotope is formed from the decay of neptunium-237?
answers: text: uranium-233

question: What isotope is it theorized will form uranium-2343 after double beta decay?
answers: text: thorium-232

question: What is the least prevalent major isotope of unnatural uranium?

question: What is the unnatural abundance of uranium-235?

question: What isotope of uranium is formed when 239U experiences spontaneous fission?

question: When uranium isotope is formed from the decay of neptunium-247?

question: What isotope is it theorized will form uranium-2343 after double alpha decay?
context: 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 these isotopes have small probabilities of undergoing spontaneous fission, rather than alpha emission. There are also five other trace isotopes: uranium-239, which is formed when 238U undergoes spontaneous fission, releasing neutrons that are captured by another 238U atom; uranium-237, which is formed when 238U captures a neutron but emits two more, which then decays to neptunium-237; uranium-233, which is formed in the decay chain of that neptunium-237; and finally, uranium-236 and -240, which appear in the decay chain of primordial plutonium-244. It is also expected that thorium-232 should be able to undergo double beta decay, which would produce uranium-232, but this has not yet been observed experimentally.

qas: question: About how many tonnes of uranium is theorized to be present in the sea?
answers: text: 4.6 billion

question: The presence of what substance in sea water has resulted in low yields when attempting to extract uranium?
answers: text: carbonate

question: What did ORNL call their material that performs surface retention on solid molecules?
answers: text: HiCap

question: Where were ORNL's results verified?
answers: text: Pacific Northwest National Laboratory

question: When was HiCap announced?
answers: text: 2012

question: About how many tonnes of uranium is theorized to be absent in the sea?

question: The presence of what substance in fresh water has resulted in low yields when attempting to extract uranium?

question: What did ORNL call their material that performs surface retention on liquid molecules?

question: Where were ORNL's results unverified?

question: When wasn't HiCap announced?
context: An additional 4.6 billion tonnes of uranium are estimated to be in sea water (Japanese scientists in the 1980s showed that extraction of uranium from sea water using ion exchangers was technically feasible). There have been experiments to extract uranium from sea water, but the yield has been low due to the carbonate present in the water. In 2012, ORNL researchers announced the successful development of a new absorbent material dubbed HiCap which performs surface retention of solid or gas molecules, atoms or ions and also effectively removes toxic metals from water, according to results verified by researchers at Pacific Northwest National Laboratory.

qas: question: What is the sole fissile isotope that occurs in nature?
answers: text: Uranium-235

question: What can be turned into plutonium-239 in a nuclear reactor?
answers: text: Uranium-238

question: What uranium isotope is produced from thorium?
answers: text: uranium-233

question: Along with uranium-235, what isotope is noted for having a high fission cross-section for slow neutrons?
answers: text: uranium-233

question: What is 238U?
answers: text: Depleted uranium

question: What is the sole fissile isotope that occurs out of nature?

question: What can't be turned into plutonium-239 in a nuclear reactor?

question: What uranium isotope is produced into thorium?

question: Along with uranium-235, what isotope is noted for having a low fission cross-section for slow neutrons?

question: What is 239U?
context: Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. While uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons, uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors, and produces the fissile material for nuclear weapons. Depleted uranium (238U) is used in kinetic energy penetrators and armor plating.

qas: question: What is OSHA?
answers: text: Occupational Safety and Health Administration

question: What is the OSHA uranium exposure limit for an 8-hour workday?
answers: text: 0.25 mg/m3

question: What does REL stand for?
answers: text: recommended exposure limit

question: What is the NIOSH uranium exposure standard over an 8-hour workday?
answers: text: 0.2 mg/m3

question: At what level of exposure does uranium become imminently dangerous to health?
answers: text: 10 mg/m3

question: What is OHSA?

question: What is the OSHA uranium exposure limit for an 9-hour workday?

question: What doesn't REL stand for?

question: What is the NIOSH plutonium exposure standard over an 8-hour workday?

question: At what level of exposure doesn't uranium become imminently dangerous to health?
context: 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 factories that process phosphate fertilizers, live near government facilities that made or tested nuclear weapons, live or work near a modern battlefield where depleted uranium weapons have been used, or live or work near a coal-fired power plant, facilities that mine or process uranium ore, or enrich uranium for reactor fuel, may have increased exposure to uranium. Houses or structures that are over uranium deposits (either natural or man-made slag deposits) may have an increased incidence of exposure to radon gas. The Occupational Safety and Health Administration (OSHA) has set the permissible exposure limit for uranium exposure in the workplace as 0.25 mg/m3 over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 0.2 mg/m3 over an 8-hour workday and a short-term limit of 0.6 mg/m3. At levels of 10 mg/m3, uranium is immediately dangerous to life and health.

qas: question: Along with UO2, what is the commonest form of uranium oxide?
answers: text: triuranium octoxide

question: What is the stablest uranium compound?
answers: text: Triuranium octoxide

question: In what form is uranium most often used as fuel for nuclear reactors?
answers: text: Uranium dioxide

question: Along with UO2, what is the least commonest form of uranium oxide?

question: What is the least stable uranium compound?

question: In what form is uranium least often used as fuel for nuclear reactors?
context: The most common forms of uranium oxide are triuranium octoxide (U
3O
8) and UO
2. Both oxide forms are solids that have low solubility in water and are relatively stable over a wide range of environmental conditions. Triuranium octoxide is (depending on conditions) the most stable compound of uranium and is the form most commonly found in nature. Uranium dioxide is the form in which uranium is most commonly used as a nuclear reactor fuel. At ambient temperatures, UO
2 will gradually convert to U
3O
8. Because of their stability, uranium oxides are generally considered the preferred chemical form for storage or disposal.

qas: question: What was the earliest year in recorded history that uranium oxide was used?
answers: text: 79 CE

question: What color of ceramic glaze was extracted from uranium oxide?
answers: text: yellow

question: In what county was glass with uranium oxide content found?
answers: text: Italy

question: In what year was yellow uranium oxide glass discovered?
answers: text: 1912

question: What institution did R.T. Gunther belong to?
answers: text: the University of Oxford

question: What was the latest year in recorded history that uranium oxide was used?

question: What color of ceramic glaze was subtracted from uranium oxide?

question: In what county was glass with uranium dioxide content found?

question: In what year was yellow uranium oxide glass undiscovered?

question: What institution did T.T. Gunther belong to?
context: The use of uranium in its natural oxide form dates back to at least the year 79 CE, when it was used to add a yellow color to ceramic glazes. Yellow glass with 1% uranium oxide was found in a Roman villa on Cape Posillipo in the Bay of Naples, Italy, by R. T. Gunther of the University of Oxford in 1912. Starting in the late Middle Ages, pitchblende was extracted from the Habsburg silver mines in Joachimsthal, Bohemia (now Jáchymov in the Czech Republic), and was used as a coloring agent in the local glassmaking industry. In the early 19th century, the world's only known sources of uranium ore were these mines.

qas: question: What was the first self-sustained nuclear chain reaction created by human beings called?
answers: text: Chicago Pile-1

question: On what date was the first self-sustained nuclear chain reaction created artificially?
answers: text: 2 December 1942

question: What project was Fermi working for?
answers: text: Manhattan

question: On the campus of what educational institution was Chicago Pile-1 created?
answers: text: University of Chicago

question: How many metric tons of uranium oxide was used in Chicago Pile-1?
answers: text: 53

question: What was the last self-sustained nuclear chain reaction created by human beings called?

question: On what date was the last self-sustained nuclear chain reaction created artificially?

question: What project wasn't Fermi working for?

question: On the campus of what educational institution was Chicago Pile-11 created?

question: How many metric tons of uranium oxide was used in Chicago Pile-21?
context: On 2 December 1942, as part of the Manhattan Project, another team led by Enrico Fermi was able to initiate the first artificial self-sustained nuclear chain reaction, Chicago Pile-1. Working in a lab below the stands of Stagg Field at the University of Chicago, the team created the conditions needed for such a reaction by piling together 400 short tons (360 metric tons) of graphite, 58 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.

qas: question: Along with lemon yellow, what color is produced in uranium glass?
answers: text: orange-red

question: Who discovered uranium in pitchblende?
answers: text: Martin Heinrich Klaproth

question: Who was responsible for first isolating uranium?
answers: text: Eugène-Melchior Péligot

question: Who discovered that uranium was radioactive?
answers: text: Henri Becquerel

question: What was the first nuclear weapon used in a war called?
answers: text: Little Boy

question: Along with lemon yellow, what color is produced in uranium plastic?

question: Who never discovered uranium in pitchblende?

question: Who was responsible for last isolating uranium?

question: Who discovered that uranium wasn't radioactive?

question: What was the last nuclear weapon used in a war called?
context: Uranium is used as a colorant in uranium glass producing orange-red to lemon yellow hues. It was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the planet Uranus. Eugène-Melchior Péligot was the first person to isolate the metal and its radioactive properties were discovered in 1896 by Henri Becquerel. Research by Otto Hahn, Lise Meitner, Enrico Fermi and others, such as J. Robert Oppenheimer starting in 1934 led to its use as a fuel in the nuclear power industry and in Little Boy, the first nuclear weapon used in war. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of nuclear weapons that used uranium metal and uranium-derived plutonium-239. The security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is an ongoing concern for public health and safety. See Nuclear proliferation.

qas: question: What percentage of uranium in nature is uranium-235?
answers: text: 0.7204%

question: What is the most prevalent natural isotope of uranium?
answers: text: uranium-238

question: What is the term for the amount of uranium-235 needed to sustain a nuclear chain reaction?
answers: text: critical mass

question: What percentage of natural uranium is isotope 238?
answers: text: 99.2742%

question: Along with gas cooled reactors, what type of reactor doesn't use uranium-235?
answers: text: pressurised heavy water

question: What percentage of uranium in nature is uranium-335?

question: What is the most prevalent unnatural isotope of uranium?

question: What is the term for the amount of uranium-335 needed to sustain a nuclear chain reaction?

question: What percentage of unnatural uranium is isotope 238?

question: Along with gas heated reactors, what type of reactor doesn't use uranium-235?
context: 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 nuclear chain reaction. The concentration and amount of uranium-235 needed to achieve this is called a 'critical mass'.

qas: question: What is uranium used for most often in the military?
answers: text: high-density penetrators

question: What percentage of high-density penetrators is not made up of depleted uranium?
answers: text: 1–2%

question: Along with titanium, what element often makes up the portion of high-density penetrators not made of depleted uranium?
answers: text: molybdenum

question: Along with the Balkans, in what geographical location did a war take place where the UK used depleted uranium munitions?
answers: text: Persian Gulf

question: What illness is possibly tied to the use of depleted uranium munitions?
answers: text: Gulf War Syndrome

question: What is uranium used for least often in the military?

question: What percentage of low-density penetrators is not made up of depleted uranium?

question: Along with titanium, what element rarely makes up the portion of high-density penetrators not made of depleted uranium?

question: Along with the Balkans, in what geographical location did a war take place where the UN used depleted uranium munitions?

question: What illness is definitely tied to the use of depleted uranium munitions?
context: 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, the density, hardness, and pyrophoricity of the projectile enable the destruction of heavily armored targets. Tank armor and other removable vehicle armor can also be hardened with depleted uranium plates. The use of depleted uranium became politically and environmentally contentious after the use of such munitions by the US, UK and other countries during wars in the Persian Gulf and the Balkans raised questions concerning uranium compounds left in the soil (see Gulf War Syndrome).

qas: question: Who discovered uranium?
answers: text: Martin Heinrich Klaproth

question: In what city was uranium discovered?
answers: text: Berlin

question: In what year did the discovery of uranium occur?
answers: text: 1789

question: What did Klaproth probably create when he dissolved pitchblende in nitric acid?
answers: text: sodium diuranate

question: Who discovered the planet Uranus?
answers: text: William Herschel

question: Who discovered plutonium?

question: n what city wasn't uranium discovered?

question: In what year didn't the discovery of uranium occur?

question: What did Klaproth definitely create when he dissolved pitchblende in nitric acid?

question: Who never discovered the planet Uranus?
context: The discovery of the element is credited to the German chemist Martin Heinrich Klaproth. While he was working in his experimental laboratory in Berlin in 1789, Klaproth was able to precipitate a yellow compound (likely sodium diuranate) by dissolving pitchblende in nitric acid and neutralizing the solution with sodium hydroxide. Klaproth assumed the yellow substance was the oxide of a yet-undiscovered element and heated it with charcoal to obtain a black powder, which he thought was the newly discovered metal itself (in fact, that powder was an oxide of uranium). He named the newly discovered element after the planet Uranus, (named after the primordial Greek god of the sky), which had been discovered eight years earlier by William Herschel.

qas: question: What percentage range of uranium oxide is usually contained in low-grade uranium ore?
answers: text: 0.01 to 0.25%

question: Along with underground, open pit and in-situ leaching, what sort of mining is used to mine uranium?
answers: text: borehole

question: In what country are high-grade uranium ores notably found?
answers: text: Canada

question: In what province of Canada is the Athabasca Basin?
answers: text: Saskatchewan

question: What is the average percentage of uranium oxide contained in the ores mined in the Athabasca Basin?
answers: text: 23%

question: What percentage range of uranium dioxide is usually contained in low-grade uranium ore?

question: Along with underground, open pit and in-situ leaching, what sort of mining is used to expel uranium?

question: In what country are high-grade uranium ores not found?

question: In what state of Canada is the Athabasca Basin?

question: What is the average percentage of uranium dioxide contained in the ores mined in the Athabasca Basin?
context: Uranium ore is mined in several ways: by open pit, underground, in-situ leaching, and borehole mining (see uranium mining). Low-grade uranium ore mined typically contains 0.01 to 0.25% uranium oxides. Extensive measures must be employed to extract the metal from its ore. High-grade ores found in Athabasca Basin deposits in Saskatchewan, Canada can contain up to 23% uranium oxides on average. Uranium ore is crushed and rendered into a fine powder and then leached with either an acid or alkali. The leachate is subjected to one of several sequences of precipitation, solvent extraction, and ion exchange. The resulting mixture, called yellowcake, contains at least 75% uranium oxides U3O8. Yellowcake is then calcined to remove impurities from the milling process before refining and conversion.

qas: question: What was the uranium-based bomb made by the US in World War II called?
answers: text: Little Boy

question: What was the codename of the plutonium-based bomb created in the Second World War?
answers: text: Fat Man

question: On what date was Little Boy detonated?
answers: text: 6 August 1945

question: What was the equivalent yield in TNT of the Little Boy bomb, in tonnes?
answers: text: 12,500

question: Over what city was Little Boy detonated?
answers: text: Hiroshima

question: What was the uranium-based bomb made by the US in World War I called?

question: What was the codename of the plutonium-based bomb destroyed in the Second World War?

question: On what date wasn't Little Boy detonated?

question: What was the equivalent yield in TNT of the Little Boy bomb, in pounds?

question: Over what city wasn't Little Boy detonated?
context: 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 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.

qas: question: As of 2005, what country was the largest producer of uranium oxides?
answers: text: Canada

question: What percentage of world uranium oxide production is produced by Argentina?
answers: text: 2.1%

question: What country produced 5.5% of the world's concentrated uranium oxide in 2005?
answers: text: Uzbekistan

question: How many tonnes of uranium was Australia expected to produce in 2009?
answers: text: 9,430

question: How many countries produced concentrated uranium oxides in 2005?
answers: text: seventeen

question: As of 2015, what country was the largest producer of uranium oxides?

question: What percentage of world uranium oxide production isn't produced by Argentina?

question: What country produced 5.5% of the world's concentrated uranium oxide in 2015?

question: How many pounds of uranium was Australia expected to produce in 2009?

question: How many countries produced concentrated uranium oxides in 2015?
context: In 2005, seventeen countries produced concentrated uranium oxides, with Canada (27.9% of world production) and Australia (22.8%) being the largest producers and Kazakhstan (10.5%), Russia (8.0%), Namibia (7.5%), Niger (7.4%), Uzbekistan (5.5%), the United States (2.5%), Argentina (2.1%), Ukraine (1.9%) and China (1.7%) also producing significant amounts. Kazakhstan continues to increase production and may have become the world's largest producer of uranium by 2009 with an expected production of 12,826 tonnes, compared to Canada with 11,100 t and Australia with 9,430 t. In the late 1960s, UN geologists also discovered major uranium deposits and other rare mineral reserves in Somalia. The find was the largest of its kind, with industry experts estimating the deposits at over 25% of the world's then known uranium reserves of 800,000 tons.

qas: question: Who was the Soviet Union's opponent in the Cold War?
answers: text: United States

question: How many nuclear warheads can be made with 540 metric tons of highly enriched weapons grade uranium?
answers: text: 40,000

question: What was the expenditure of the Material Protection, Control, and Accounting Program between 1993 and 2005?
answers: text: US $550 million

question: What is another term for uranium that is enriched?
answers: text: weapons grade

question: Approximately how many times did police capture shipments of bomb-grade plutonium or uranium between 1993 and 2005?
answers: text: 16

question: Who was the Soviet Union's ally in the Cold War?

question: How many nuclear warheads can be made with 450 metric tons of highly enriched weapons grade uranium?

question: What was the expenditure of the Material Protection, Control, and Accounting Program between 1995 and 2005?

question: What is another term for uranium that is not enriched?

question: Approximately how many times did police capture shipments of bomb-grade plutonium or uranium between 1993 and 2003?
context: During the Cold War between the Soviet Union and the United States, huge stockpiles of uranium were amassed and tens of thousands of nuclear weapons were created using enriched uranium and plutonium made from uranium. Since the break-up of the Soviet Union in 1991, an estimated 600 short tons (540 metric tons) of highly enriched weapons grade uranium (enough to make 40,000 nuclear warheads) have been stored in often inadequately guarded facilities in the Russian Federation and several other former Soviet states. Police in Asia, Europe, and South America on at least 16 occasions from 1993 to 2005 have intercepted shipments of smuggled bomb-grade uranium or plutonium, most of which was from ex-Soviet sources. From 1993 to 2005 the Material Protection, Control, and Accounting Program, operated by the federal government of the United States, spent approximately US $550 million to help safeguard uranium and plutonium stockpiles in Russia. This money was used for improvements and security enhancements at research and storage facilities. Scientific American reported in February 2006 that in some of the facilities security consisted of chain link fences which were in severe states of disrepair. According to an interview from the article, one facility had been storing samples of enriched (weapons grade) 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.

qas: question: What is the color of U4+?
answers: text: green

question: What state is represented by the UO2+ 2 ion?
answers: text: uranium(VI)

question: Along with uranyl sulfate and uranyl chloride, what compound is formed by the UO2+ 2 ion?
answers: text: uranyl carbonate

question: What common complex is formed by the UO2+ 2 ion with organic chelating agents?
answers: text: uranyl acetate

question: What is the color of U4-?

question: What state isn't represented by the UO2+ 2 ion?

question: Along with uranyl sulfate and uranyl chloride, what compound isn't formed by the UO2+ 2 ion?

question: What uncommon complex is formed by the UO2+ 2 ion with organic chelating agents?
context: Salts of many oxidation states of uranium are water-soluble and may be studied in aqueous solutions. The most common ionic forms are U3+ (brown-red), U4+ (green), UO+
2 (unstable), and UO2+
2 (yellow), for U(III), U(IV), U(V), and U(VI), respectively. A few solid and semi-metallic compounds such as UO and US exist for the formal oxidation state uranium(II), but no simple ions are known to exist in solution for that state. Ions of U3+ liberate hydrogen from water and are therefore considered to be highly unstable. The UO2+
2 ion represents the uranium(VI) state and is known to form compounds such as uranyl carbonate, uranyl chloride and uranyl sulfate. UO2+
2 also forms complexes with various organic chelating agents, the most commonly encountered of which is uranyl acetate.

qas: question: What microorganism can notably absorb a very high concentrate of uranium?
answers: text: Citrobacter

question: What lichen is known to absorb a uranium concentration nearly 300 times higher than the amount in the environment?
answers: text: Trapelia involuta

question: What is given to Citrobacter to cause it to absorb uranyl ions?
answers: text: glycerol phosphate

question: What protobacterium notably bioremediates ground water uranium?
answers: text: Geobacter

question: What fungus is known to cause uranium content in its symbiotic plant roots to increase?
answers: text: Glomus intraradices

question: What macroorganism can notably absorb a very high concentrate of uranium?

question: What lichen is known to absorb a uranium concentration nearly 400 times higher than the amount in the environment?

question: What is taken from Citrobacter to cause it to absorb uranyl ions?

question: What protobacterium never bioremediates ground water uranium?

question: What fungus is known to cause uranium content in its symbiotic plant roots to decrease?
context: Some organisms, such as the lichen Trapelia involuta or microorganisms such as the bacterium Citrobacter, can absorb concentrations of uranium that are up to 300 times the level of their environment. Citrobacter species absorb uranyl ions when given glycerol phosphate (or other similar organic phosphates). After one day, one gram of bacteria can encrust themselves with nine grams of uranyl phosphate crystals; this creates the possibility that these organisms could be used in bioremediation to decontaminate uranium-polluted water. The proteobacterium Geobacter has also been shown to bioremediate uranium in ground water. The mycorrhizal fungus Glomus intraradices increases uranium content in the roots of its symbiotic plant.

qas: question: At what temperature range in degrees Fahrenheit will uranium metal form uranium hydride?
answers: text: 482 to 572

question: What does uranium metal react with to create uranium hydride?
answers: text: hydrogen

question: Above what temperature is the β form of uranium hydride created?
answers: text: 250 °C

question: Along with uranium carbide and halide, what type of compound is often created with uranium hydride?
answers: text: nitride

question: How many crystal modifications of uranium hydride are extant?
answers: text: Two

question: At what temperature range in degrees Fahrenheit won't uranium metal form uranium hydride?

question: What doesn't uranium metal react with to create uranium hydride?

question: Above what temperature is the β form of uranium hydride destroyed?

question: Along with uranium carbide and halide, what type of compound is often destroyed with uranium hydride?

question: How many crystal modifications of plutonium hydride are extant?
context: Uranium metal heated to 250 to 300 °C (482 to 572 °F) reacts with hydrogen to form uranium hydride. Even higher temperatures will reversibly remove the hydrogen. This property makes uranium hydrides convenient starting materials to create reactive uranium powder along with various uranium carbide, nitride, and halide compounds. Two crystal modifications of uranium hydride exist: an α form that is obtained at low temperatures and a β form that is created when the formation temperature is above 250 °C.

qas: question: Along with uranium monocarbide and uranium dicarbide, what is a notable carbide of uranium?
answers: text: diuranium tricarbide

question: Below what temperature is U2C3 stable?
answers: text: 1800 °C

question: Along with uranium monocarbide and uranium dicarbide, what is a unnotable carbide of uranium?

question: Below what temperature is U2C3 unstable?
context: Uranium carbides and uranium nitrides are both relatively inert semimetallic compounds that are minimally soluble in acids, react with water, and can ignite in air to form U
3O
8. Carbides of uranium include uranium monocarbide (UC), uranium dicarbide (UC
2), and diuranium tricarbide (U
2C
3). Both UC and UC
2 are formed by adding carbon to molten uranium or by exposing the metal to carbon monoxide at high temperatures. Stable below 1800 °C, U
2C
3 is prepared by subjecting a heated mixture of UC and UC
2 to mechanical stress. Uranium nitrides obtained by direct exposure of the metal to nitrogen include uranium mononitride (UN), uranium dinitride (UN
2), and diuranium trinitride (U
2N
3).

qas: question: Between what percent fraction range of uranium-235 is uranium regarded as enriched?
answers: text: 3% and 5%

question: What is the maximum uranium-235 isotope concentration for uranium to be considered depleted?
answers: text: 0.3%

question: In what year did the cost of uranium notably begin to increase?
answers: text: 2001

question: What was the price of a kilogram of depleted uranium hexafluoride in 2001?
answers: text: $5

question: How much did a kilogram of depleted uranium hexafluoride cost as of July 2007?
answers: text: $130

question: Between what percent fraction range of uranium-235 is uranium regarded as unenriched?

question: What is the maximum uranium-235 isotope concentration for plutonium to be considered depleted?

question: In what year did the cost of uranium notably begin to decrease?

question: What was the price of a pound of depleted uranium hexafluoride in 2001?

question: How much did a pound of depleted uranium hexafluoride cost as of July 2007?
context: To be considered 'enriched', the uranium-235 fraction should be between 3% and 5%. This process produces huge quantities of uranium that is depleted of uranium-235 and with a correspondingly increased fraction of uranium-238, called depleted uranium or 'DU'. To be considered 'depleted', the uranium-235 isotope concentration should be no more than 0.3%. The price of uranium has risen since 2001, so enrichment tailings containing more than 0.35% uranium-235 are being considered for re-enrichment, driving the price of depleted uranium hexafluoride above $130 per kilogram in July 2007 from $5 in 2001.

qas: question: Along with the heart, brain and liver, what system is notably affected by exposure to uranium?
answers: text: kidney

question: What is the main form of 238U decay?
answers: text: alpha radiation

question: What type of uranium compounds are uranium trioxide and uranyl nitrate?
answers: text: hexavalent

question: At what temperature will grains of uranium metal spontaneously ignite in air?
answers: text: room

question: Along with the heart, brain and liver, what system is notably unaffected by exposure to uranium?

question: What is the main form of 239U decay?

question: What type of uranium compounds are uranium dioxide and uranyl nitrate?

question: At what temperature will grains of plutonium metal spontaneously ignite in air?
context: Normal functioning of the kidney, brain, liver, heart, and other systems can be affected by uranium exposure, because, besides being weakly radioactive, uranium is a toxic metal. Uranium is also a reproductive toxicant. Radiological effects are generally local because alpha radiation, the primary form of 238U decay, has a very short range, and will not penetrate skin. Uranyl (UO2+
2) ions, such as from uranium trioxide or uranyl nitrate and other hexavalent uranium compounds, have been shown to cause birth defects and immune system damage in laboratory animals. While the CDC has published one study that no human cancer has been seen as a result of exposure to natural or depleted uranium, exposure to uranium and its decay products, especially radon, are widely known and significant health threats. Exposure to strontium-90, iodine-131, and other fission products is unrelated to uranium exposure, but may result from medical procedures or exposure to spent reactor fuel or fallout from nuclear weapons. Although accidental inhalation exposure to a high concentration of uranium hexafluoride has resulted in human fatalities, those deaths were associated with the generation of highly toxic hydrofluoric acid and uranyl fluoride rather than with uranium itself. Finely divided uranium metal presents a fire hazard because uranium is pyrophoric; small grains will ignite spontaneously in air at room temperature.

qas: question: What is the name of the most widely used enrichment process?
answers: text: gas centrifuge

question: What compound is UF6?
answers: text: uranium hexafluoride

question: What enrichment process was used by the Manhattan Project?
answers: text: gaseous diffusion

question: In the gaseous diffusion process, what is diffused through a silver-zinc membrane?
answers: text: uranium hexafluoride

question: How does the weight of uranium-238 compare to that of uranium-235?
answers: text: heavier

question: What is the name of the least widely used enrichment process?

question: What compound is UF5?

question: What enrichment process wasn't used by the Manhattan Project?

question: In the gaseous diffusion process, what is diffused through a gold-zinc membrane?

question: How does the height of uranium-238 compare to that of uranium-235?
context: The gas centrifuge process, where gaseous uranium hexafluoride (UF
6) is separated by the difference in molecular weight between 235UF6 and 238UF6 using high-speed centrifuges, is the cheapest and leading enrichment process. The gaseous diffusion process had been the leading method for enrichment and was used in the Manhattan Project. In this process, uranium hexafluoride is repeatedly diffused through a silver-zinc membrane, and the different isotopes of uranium are separated by diffusion rate (since uranium 238 is heavier it diffuses slightly slower than uranium-235). The molecular laser isotope separation method employs a 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.

qas: question: What is uranium's symbol on the Periodic Table of Elements?
answers: text: U

question: What is the atomic number of uranium?
answers: text: 92

question: What color is uranium?
answers: text: silvery-white

question: Of what series in the Periodic Table of Elements is uranium a part?
answers: text: actinide

question: How many valence electrons are contained in an atom of uranium?
answers: text: 6

question: What isn't uranium's symbol on the Periodic Table of Elements?

question: What isn't the atomic number of uranium?

question: What shape is uranium?

question: Of what series in the Periodic Table of Elements is uranium not a part?

question: How many valence electrons aren't contained in an atom of uranium?
context: Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-white 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 its isotopes are unstable (with half-lives of the six naturally known isotopes, uranium-233 to uranium-238, varying between 69 years and 4.5 billion years). The most common isotopes of uranium are uranium-238 (which has 146 neutrons and accounts for almost 99.3% of the uranium found in nature) and uranium-235 (which has 143 neutrons, accounting for 0.7% of the element found naturally). Uranium has the second highest atomic weight of the primordially occurring elements, lighter only than plutonium. Its density is about 70% higher than that of lead, but slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.

qas: question: What non-metal elements does uranium notably not react to?
answers: text: noble gases

question: Along with nitric acids, what acids dissolve uranium?
answers: text: Hydrochloric

question: What coats uranium metal in air?
answers: text: uranium oxide

question: What is a notable form uranium ore is converted into after extraction?
answers: text: uranium dioxide

question: What reacts with finely divided uranium?
answers: text: cold water

question: What non-metal elements does uranium notably react to?

question: Along with nitric acids, what acids dissolve in uranium?

question: What coats uranium metal in liquid?

question: What is a notable form uranium ore is converted into before extraction?

question: What reacts with finely multiplied uranium?
context: Uranium metal reacts with almost all non-metal elements (with an exception of the noble gases) and their compounds, with reactivity increasing with temperature. Hydrochloric and nitric acids dissolve uranium, but non-oxidizing acids other than hydrochloric acid attack the element very slowly. When finely divided, it can react with cold water; in air, uranium metal becomes coated with a dark layer of uranium oxide. Uranium in ores is extracted chemically and converted into uranium dioxide or other chemical forms usable in industry.

qas: question: During what war was uranium-235 first used to create nuclear weapons?
answers: text: World War II

question: From what isotope of uranium is plutonium-239 derived?
answers: text: 238

question: What is mixed with tritium and experiences nuclear fusion in a fission/fusion bomb?
answers: text: deuterium

question: What is another name for a fission/fusion bomb?
answers: text: thermonuclear weapon

question: What does non-fissile mean?
answers: text: unenriched

question: During what war was uranium-235 last used to create nuclear weapons?

question: From what isotope of uranium is plutonium-249 derived?

question: What isn't mixed with tritium and experiences nuclear fusion in a fission/fusion bomb?

question: What is another name for a fission/fusion boat?

question: What does fissile mean?
context: During the later stages of World War II, the entire Cold War, and to a lesser extent afterwards, uranium-235 has been used as the fissile explosive material to produce nuclear weapons. Initially, two major types of fission bombs were built: a relatively simple device that uses uranium-235 and a more complicated mechanism that uses plutonium-239 derived from uranium-238. Later, a much more complicated and far more powerful type of fission/fusion bomb (thermonuclear weapon) was built, that uses a plutonium-based device to cause a mixture of tritium and deuterium to undergo nuclear fusion. Such bombs are jacketed in a non-fissile (unenriched) uranium case, and they derive more than half their power from the fission of this material by fast neutrons from the nuclear fusion process.

qas: question: What product of uranium was used as toner?
answers: text: nitrate

question: Along with uranyl formate, what product of uranium is used in transmission electron microscopy?
answers: text: Uranyl acetate

question: What light bulbs use lamp filaments containing uranium?
answers: text: stage

question: Along with leather, what industry uses uranium in dyes and stains?
answers: text: wood

question: In addition to wool, what is uranium salt a mordant of?
answers: text: silk

question: What product of uranium wasn't used as toner?

question: Along with uranyl formate, what product of uranium is used in transmission proton microscopy?

question: What light bulbs don't use lamp filaments containing uranium?

question: Along with leather, what industry uses no uranium in dyes and stains?

question: In addition to wool, what isn't uranium salt a mordant of?
context: Uranium was also used in photographic chemicals (especially uranium nitrate as a toner), in lamp filaments for stage lighting bulbs, to improve the appearance of dentures, and in the leather and wood industries for stains and dyes. Uranium salts are mordants of silk or wool. Uranyl acetate and uranyl formate are used as electron-dense "stains" in transmission electron microscopy, to increase the contrast of biological specimens in ultrathin sections and in negative staining of viruses, isolated cell organelles and macromolecules.

qas: question: Of what nationality was Perrin?
answers: text: French

question: In what county was the Oklo mine located?
answers: text: Gabon

question: How old are the ore deposits in the Oklo mine?
answers: text: 1.7 billion years

question: When the Oklo mine ore deposits came into being, what percentage of uranium on Earth consisted of uranium-235?
answers: text: 3%

question: Where in the United States is there a nuclear waste repository?
answers: text: Yucca Mountain

question: Of what nationality wasn't Perrin?

question: In what country was the Oklo mine not located

question: How old are the ore deposits in the Oslo mine?

question: When the Oklo mine ore deposits came into being, what percentage of uranium on Earth consisted of uranium-253?

question: Where in the United States is there no nuclear waste repository?
context: In 1972, the French physicist Francis Perrin discovered fifteen ancient and no longer active natural nuclear fission reactors in three separate ore deposits at the Oklo mine in Gabon, West Africa, collectively known as the Oklo Fossil Reactors. The ore deposit is 1.7 billion years old; then, uranium-235 constituted about 3% of the total uranium on Earth. This is high enough to permit a sustained nuclear fission chain reaction to occur, provided other supporting conditions exist. The capacity of the surrounding sediment to contain the nuclear waste products has been cited by the U.S. federal government as supporting evidence for the feasibility to store spent nuclear fuel at the Yucca Mountain nuclear waste repository.

qas: question: How many times more abundant than silver is uranium in the Earth's crust?
answers: text: 40

question: How many kilograms of uranium may be contained in the oceans?
answers: text: 1013

question: Why is the concentrate of uranium in farmland so high?
answers: text: phosphate fertilizers

question: What is the concentration of uranium in sea water?
answers: text: 3 parts per billion

question: How many times less abundant than silver is uranium in the Earth's crust?

question: How many pounds of uranium may be contained in the oceans?

question: Why is the concentrate of uranium in farmland so low?

question: What is the concentration of uranium in fresh water?

question: What is the concentration of plutonium in sea water?
context: Uranium's average concentration in the Earth's crust is (depending on the reference) 2 to 4 parts per million, or about 40 times as abundant as silver. The Earth's crust from the surface to 25 km (15 mi) down is calculated to contain 1017 kg (2×1017 lb) of uranium while the oceans may contain 1013 kg (2×1013 lb). The concentration of uranium in soil ranges from 0.7 to 11 parts per million (up to 15 parts per million in farmland soil due to use of phosphate fertilizers), and its concentration in sea water is 3 parts per billion.

qas: question: What isotope of uranium has the most stability?
answers: text: Uranium-238

question: About how old is the Earth?
answers: text: 4.468×109 years

question: What is the half-life of uranium-234?
answers: text: 2.48×105 years

question: What fraction of the Earth's uranium was uranium-235 during the Earth's youth?
answers: text: one-fifth

question: What percentage of the alpha rays of natural uranium are emitted by 234U?
answers: text: 49%

question: What isotope of uranium has the least stability?

question: About how gold is the Earth?

question: What is the full-life of uranium-234?

question: What fraction of the Earth's uranium was uranium-237 during the Earth's youth?

question: What percentage of the gamma rays of natural uranium are emitted by 234U?
context: Uranium-238 is the most stable isotope of uranium, with a half-life of about 4.468×109 years, roughly the age of the Earth. Uranium-235 has a half-life of about 7.13×108 years, and uranium-234 has a half-life of about 2.48×105 years. For natural uranium, about 49% of its alpha rays are emitted by each of 238U atom, and also 49% by 234U (since the latter is formed from the former) and about 2.0% of them by the 235U. When the Earth was young, probably about one-fifth of its uranium was uranium-235, but the percentage of 234U was probably much lower than this.

qas: question: What happens to a majority of ingested uranium?
answers: text: excreted

question: Up to what percentage of uranyl ion can be absorbed when ingested?
answers: text: 5%

question: About what percentage of uranium oxide is absorbed when ingested?
answers: text: 0.5%

question: What does uranium have an affinity for?
answers: text: phosphates

question: Where does uranium accumulate in the body?
answers: text: bone tissue

question: What happens to a minority of ingested uranium?

question: Up to what percentage of uranyl ion can be absorbed when digested?

question: About what percentage of uranium dioxide is absorbed when ingested?

question: What does uranium not have an affinity for?

question: Where doesn't uranium accumulate in the body?
context: Most ingested uranium is excreted during digestion. Only 0.5% is absorbed when insoluble forms of uranium, such as its oxide, are ingested, whereas absorption of the more soluble uranyl ion can be up to 5%. However, soluble uranium compounds tend to quickly pass through the body, whereas insoluble uranium compounds, especially when inhaled by way of dust into the lungs, pose a more serious exposure hazard. After entering the bloodstream, the absorbed uranium tends to bioaccumulate and stay for many years in bone tissue because of uranium's affinity for phosphates. Uranium is not absorbed through the skin, and alpha particles released by uranium cannot penetrate the skin.

qas: question: What contains a distribution of uranium deoxidation species in various forms ranging from most oxidized to least oxidized?

question: What contains a distribution of uranium oxidation species in no forms ranging from most oxidized to least oxidized?

question: What will generally be less oxidized than those with short retention times or particles recovered in the stack scrubber?

question: What will generally be less oxidized than those with long retention times or particles replaced in the stack scrubber?

question: What will never be less oxidized than those with long retention times or particles recovered in the stack scrubber?
context: Calcined uranium yellowcake, as produced in many large mills, contains a distribution of uranium oxidation species in various forms ranging from most oxidized to least oxidized. Particles with short residence times in a calciner will generally be less oxidized than those with long retention times or particles recovered in the stack scrubber. Uranium content is usually referenced to U
3O
8, which dates to the days of the Manhattan project when U
3O
8 was used as an analytical chemistry reporting standard.