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73-455: The Japan Atomic Energy Agency is a Japanese atomic energy company. While it inherited the activities of both JNC and JAERI , it also inherited the nickname of JAERI, "Genken" 原研, an abbreviated word for "nuclear research". On April 10, 2007, JAEA officially joined the GNEP alliance. The other members in the alliance are Areva , Washington Group International and BWX. It is expected that

146-579: A critical mass . During the early stages of research, animals were used to study the effects of radioactive substances on health. These studies began in 1944 at the University of California at Berkeley's Radiation Laboratory and were conducted by Joseph G. Hamilton. Hamilton was looking to answer questions about how plutonium would vary in the body depending on exposure mode (oral ingestion, inhalation, absorption through skin), retention rates, and how plutonium would be fixed in tissues and distributed among

219-422: A fertile material . Twenty-two radioisotopes of plutonium have been characterized, from Pu to Pu. The longest-lived are Pu, with a half-life of 80.8 million years; Pu, with a half-life of 373,300 years; and Pu, with a half-life of 24,110 years. All other isotopes have half-lives of less than 7,000 years. This element also has eight metastable states , though all have half-lives less than

292-458: A multiplication factor (k eff ) larger than one, which means that if the metal is present in sufficient quantity and with an appropriate geometry (e.g., a sphere of sufficient size), it can form a critical mass . During fission, a fraction of the nuclear binding energy , which holds a nucleus together, is released as a large amount of electromagnetic and kinetic energy (much of the latter being quickly converted to thermal energy). Fission of

365-450: A nuclear chain reaction , leading to applications in nuclear weapons and nuclear reactors . Plutonium-240 has a high rate of spontaneous fission , raising the neutron flux of any sample containing it. The presence of plutonium-240 limits a plutonium sample's usability for weapons or its quality as reactor fuel, and the percentage of plutonium-240 determines its grade ( weapons-grade , fuel-grade, or reactor-grade). Plutonium-238 has

438-414: A vacuum or an inert atmosphere to avoid reaction with air. At 135 °C the metal will ignite in air and will explode if placed in carbon tetrachloride . Plutonium is a reactive metal. In moist air or moist argon , the metal oxidizes rapidly, producing a mixture of oxides and hydrides . If the metal is exposed long enough to a limited amount of water vapor, a powdery surface coating of PuO 2

511-552: A Research and Development (R&D) center. This center is located in Ōarai , Ibaraki Prefecture , close to, but not at the same site as Tokai-mura. It houses the Jōyō reactor, the Japan Materials Testing Reactor , the new High-temperature engineering test reactor , an environmental reactivity monitoring center, and a children's museum. This is a small uranium refining and conversion plant, as well as

584-508: A half-life of 87.7 years and emits alpha particles . It is a heat source in radioisotope thermoelectric generators , which are used to power some spacecraft . Plutonium isotopes are expensive and inconvenient to separate, so particular isotopes are usually manufactured in specialized reactors. Producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II that developed

657-431: A kilogram of plutonium-239 can produce an explosion equivalent to 21,000 tons of TNT (88,000  GJ ). It is this energy that makes plutonium-239 useful in nuclear weapons and reactors . The presence of the isotope plutonium-240 in a sample limits its nuclear bomb potential, as Pu has a relatively high spontaneous fission rate (~440 fissions per second per gram; over 1,000 neutrons per second per gram), raising

730-463: A large range of temperatures (over 2,500 kelvin wide) at which plutonium is liquid, but this range is neither the greatest among all actinides nor among all metals, with neptunium theorized to have the greatest range in both instances. The low melting point as well as the reactivity of the native metal compared to the oxide leads to plutonium oxides being a preferred form for applications such as nuclear fission reactor fuel ( MOX-fuel ). Alpha decay ,

803-426: A limited pressure range. These allotropes, which are different structural modifications or forms of an element, have very similar internal energies but significantly varying densities and crystal structures . This makes plutonium very sensitive to changes in temperature, pressure, or chemistry, and allows for dramatic volume changes following phase transitions from one allotropic form to another. The densities of

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876-512: A materials irradiation test facility. The facilities in Mutsu include a museum, an ocean monitoring facility, and radioactive waste management. JAEA also co-operates and provides support for the activities of Japan Nuclear Fuel Limited with their reprocessing facility and Uranium enrichment facility plans. The Horonobe URL carries out research and development on geoscientific study and on geological disposal for high-level radioactive waste. It

949-454: A reduction mechanism similar to FeO 4 , PuO 4 can be stabilized in alkaline solutions and chloroform . Metallic plutonium is produced by reacting plutonium tetrafluoride with barium , calcium or lithium at 1200 °C. Metallic plutonium is attacked by acids , oxygen , and steam but not by alkalis and dissolves easily in concentrated hydrochloric , hydroiodic and perchloric acids . Molten metal must be kept in

1022-493: A relatively short half-life, U decays to Np, which decays into Pu. Finally, exceedingly small amounts of plutonium-238, attributed to the extremely rare double beta decay of uranium-238, have been found in natural uranium samples. Due to its relatively long half-life of about 80 million years, it was suggested that plutonium-244 occurs naturally as a primordial nuclide , but early reports of its detection could not be confirmed. Based on its likely initial abundance in

1095-507: A second. Pu has been found in interstellar space and it has the longest half-life of any non-primordial radioisotope. The main decay modes of isotopes with mass numbers lower than the most stable isotope, Pu, are spontaneous fission and alpha emission , mostly forming uranium (92 protons ) and neptunium (93 protons) isotopes as decay products (neglecting the wide range of daughter nuclei created by fission processes). The main decay mode for isotopes heavier than Pu, along with Pu and Pu,

1168-483: A small centrifuge enrichment demonstration plant located in Kamisaibara , Okayama Prefecture . The center deals with front-end issues of the nuclear fuel cycle. The Aomori Research and Development Center is spread out over Rokkasho , Aomori Prefecture and Mutsu , Aomori Prefecture . The Rokkasho site does work with fusion research, notably a fusion reactor design research institute, a particle accelerator, and

1241-399: Is beta emission , forming americium isotopes (95 protons). Plutonium-241 is the parent isotope of the neptunium series , decaying to americium-241 via beta emission. Plutonium-238 and 239 are the most widely synthesized isotopes. Pu is synthesized via the following reaction using uranium (U) and neutrons (n) via beta decay (β ) with neptunium (Np) as an intermediate: Neutrons from

1314-490: Is plutonocene . Computational chemistry methods indicate an enhanced covalent character in the plutonium-ligand bonding. Powders of plutonium, its hydrides and certain oxides like Pu 2 O 3 are pyrophoric , meaning they can ignite spontaneously at ambient temperature and are therefore handled in an inert, dry atmosphere of nitrogen or argon. Bulk plutonium ignites only when heated above 400 °C. Pu 2 O 3 spontaneously heats up and transforms into PuO 2 , which

1387-417: Is a chemical element ; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized . The element normally exhibits six allotropes and four oxidation states . It reacts with carbon , halogens , nitrogen , silicon , and hydrogen . When exposed to moist air, it forms oxides and hydrides that can expand

1460-485: Is a radioactive actinide metal whose isotope , plutonium-239 , is one of the three primary fissile isotopes ( uranium-233 and uranium-235 are the other two); plutonium-241 is also highly fissile. To be considered fissile, an isotope's atomic nucleus must be able to break apart or fission when struck by a slow moving neutron and to release enough additional neutrons to sustain the nuclear chain reaction by splitting further nuclei. Pure plutonium-239 may have

1533-622: Is an incomplete list of its activities, sorted by location: JAEA has several facilities located in Tōkai , Ibaraki Prefecture , which was the first center in Japan for nuclear research. Currently, JAEA has expanded to several other sites in the Ibaraki Prefecture as well as all of Japan. JAEA has another head base in Tsuruga , Fukui Prefecture . It is a fast breeder reactor center and

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1606-599: Is expected that this site will become Japan's national Deep geological repository for nuclear waste. This is located in Tōnō , Gifu Prefecture . Japan Nuclear Cycle Development Institute Predecessor organisation to the Japanese nuclear agency The Japan Nuclear Cycle Development Institute ( JNC ) was formed in October 1998 to develop advanced nuclear energy technology to complete

1679-429: Is formed. Also formed is plutonium hydride but an excess of water vapor forms only PuO 2 . Plutonium shows enormous, and reversible, reaction rates with pure hydrogen, forming plutonium hydride . It also reacts readily with oxygen, forming PuO and PuO 2 as well as intermediate oxides; plutonium oxide fills 40% more volume than plutonium metal. The metal reacts with the halogens , giving rise to compounds with

1752-460: Is in its α ( alpha ) form . This allotrope is about as hard and brittle as gray cast iron . When plutonium is alloyed with other metals, the high-temperature δ allotrope is stabilized at room temperature, making it soft and ductile. Unlike most metals, it is not a good conductor of heat or electricity . It has a low melting point (640 °C, 1,184 °F) and an unusually high boiling point (3,228 °C, 5,842 °F). This gives

1825-426: Is likely that Hahn and Strassmann were aware that plutonium-239 should be fissile. However, they did not have a strong neutron source. Element 93 was reported by Hahn and Strassmann, as well as Starke, in 1942. Hahn's group did not pursue element 94, likely because they were discouraged by McMillan and Abelson's lack of success in isolating it when they had first found element 93. However, since Hahn's group had access to

1898-435: Is responsible for directional covalent bonds in molecules and complexes of plutonium. Plutonium can form alloys and intermediate compounds with most other metals. Exceptions include lithium, sodium , potassium , rubidium and caesium of the alkali metals ; and magnesium , calcium, strontium , and barium of the alkaline earth metals ; and europium and ytterbium of the rare earth metals . Partial exceptions include

1971-414: Is roughly as strong and malleable as aluminium. In fission weapons, the explosive shock waves used to compress a plutonium core will also cause a transition from the usual δ phase plutonium to the denser α form, significantly helping to achieve supercriticality . The ε phase, the highest temperature solid allotrope, exhibits anomalously high atomic self-diffusion compared to other elements. Plutonium

2044-402: Is stable in dry air, but reacts with water vapor when heated. Crucibles used to contain plutonium need to be able to withstand its strongly reducing properties. Refractory metals such as tantalum and tungsten along with the more stable oxides, borides , carbides , nitrides and silicides can tolerate this. Melting in an electric arc furnace can be used to produce small ingots of

2117-584: Is the element with the highest atomic number known to occur in nature. Trace quantities arise in natural uranium deposits when uranium-238 captures neutrons emitted by decay of other uranium-238 atoms. The heavy isotope plutonium-244 has a half-life long enough that extreme trace quantities should have survived primordially (from the Earth's formation) to the present, but so far experiments have not yet been sensitive enough to detect it. Both plutonium-239 and plutonium-241 are fissile , meaning they can sustain

2190-544: Is unusual for metals. This trend continues down to 100  K , below which resistivity rapidly decreases for fresh samples. Resistivity then begins to increase with time at around 20 K due to radiation damage, with the rate dictated by the isotopic composition of the sample. Because of self-irradiation, a sample of plutonium fatigues throughout its crystal structure, meaning the ordered arrangement of its atoms becomes disrupted by radiation with time. Self-irradiation can also lead to annealing which counteracts some of

2263-404: Is used in U.S. Navy weapons stored near ship and submarine crews, due to its lower radioactivity. Plutonium-238 is not fissile but can undergo nuclear fission easily with fast neutrons as well as alpha decay. All plutonium isotopes can be "bred" into fissile material with one or more neutron absorptions , whether followed by beta decay or not. This makes non-fissile isotopes of plutonium

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2336-429: Is usually listed as watt/kilogram, or milliwatt/gram. In larger pieces of plutonium (e.g. a weapon pit) and inadequate heat removal the resulting self-heating may be significant. At room temperature, pure plutonium is silvery in color but gains a tarnish when oxidized. The element displays four common ionic oxidation states in aqueous solution and one rare one: The color shown by plutonium solutions depends on both

2409-464: The Cigar Lake Mine uranium deposit ranges from 2.4 × 10 to 44 × 10 . These trace amounts of Pu originate in the following fashion: on rare occasions, U undergoes spontaneous fission, and in the process, the nucleus emits one or two free neutrons with some kinetic energy. When one of these neutrons strikes the nucleus of another U atom, it is absorbed by the atom, which becomes U. With

2482-472: The Cold War is a nuclear-proliferation and environmental concern. Other sources of plutonium in the environment are fallout from many above-ground nuclear tests, which are now banned . Plutonium, like most metals, has a bright silvery appearance at first, much like nickel , but it oxidizes very quickly to a dull gray, though yellow and olive green are also reported. At room temperature plutonium

2555-459: The Manhattan Project , for developing an atomic bomb. The three primary research and production sites of the project were the plutonium production facility at what is now the Hanford Site ; the uranium enrichment facilities at Oak Ridge, Tennessee ; and the weapons research and design lab, now known as Los Alamos National Laboratory , LANL. The first production reactor that made Pu was

2628-801: The nuclear fuel cycle , particularly fast breeder reactors , advanced reprocessing , plutonium fuel fabrication and high-level radioactive waste management . It succeeded the Power Reactor and Nuclear Fuel Development Corporation (PNC). It merged with the Japan Atomic Energy Research Institute (JAERI) in October 2005, becoming the Japan Atomic Energy Agency (JAEA). See also [ edit ] Nuclear power in Japan References [ edit ] Official site on

2701-502: The r-process in supernovae and colliding neutron stars ; when nuclei are ejected from these events at high speed to reach Earth, Pu alone among transuranic nuclides has a long enough half-life to survive the journey, and hence tiny traces of live interstellar Pu have been found in the deep sea floor. Because Pu also occurs in the decay chain of Pu, it must thus also be present in secular equilibrium , albeit in even tinier quantities. Minute traces of plutonium are usually found in

2774-469: The 6d and 5f subshells is very low. The size of the 5f shell is just enough to allow the electrons to form bonds within the lattice, on the very boundary between localized and bonding behavior. The proximity of energy levels leads to multiple low-energy electron configurations with near equal energy levels. This leads to competing 5f 7s and 5f 6d 7s configurations, which causes the complexity of its chemical behavior. The highly directional nature of 5f orbitals

2847-610: The JAEA site History of Japan Nuclear Cycle Development Institute Authority control databases [REDACTED] International VIAF National Japan Czech Republic Retrieved from " https://en.wikipedia.org/w/index.php?title=Japan_Nuclear_Cycle_Development_Institute&oldid=1036980090 " Category : Nuclear technology organizations of Japan Hidden categories: Articles with short description Short description matches Wikidata Plutonium Plutonium

2920-541: The Solar System, present experiments as of 2022 are likely about an order of magnitude away from detecting live primordial Pu. However, its long half-life ensured its circulation across the solar system before its extinction , and indeed, evidence of the spontaneous fission of extinct Pu has been found in meteorites. The former presence of Pu in the early Solar System has been confirmed, since it manifests itself today as an excess of its daughters, either Th (from

2993-484: The X-10 reactor. Information from CP-1 was also useful to Met Lab scientists designing the water-cooled plutonium production reactors for Hanford. Construction at the site began in mid-1943. In November 1943 some plutonium trifluoride was reduced to create the first sample of plutonium metal: a few micrograms of metallic beads. Enough plutonium was produced to make it the first synthetically made element to be visible with

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3066-490: The advantage of avoiding dealing directly with the highly reactive plutonium metal. Trace amounts of plutonium-238, plutonium-239, plutonium-240, and plutonium-244 can be found in nature. Small traces of plutonium-239, a few parts per trillion , and its decay products are naturally found in some concentrated ores of uranium, such as the natural nuclear fission reactor in Oklo , Gabon . The ratio of plutonium-239 to uranium at

3139-416: The alpha decay pathway) or xenon isotopes (from its spontaneous fission ). The latter are generally more useful, because the chemistries of thorium and plutonium are rather similar (both are predominantly tetravalent) and hence an excess of thorium would not be strong evidence that some of it was formed as a plutonium daughter. Pu has the longest half-life of all transuranic nuclides and is produced only in

3212-399: The background neutron levels and thus increasing the risk of predetonation . Plutonium is identified as either weapons-grade , fuel-grade, or reactor-grade based on the percentage of Pu that it contains. Weapons-grade plutonium contains less than 7% Pu. Fuel-grade plutonium contains 7%–19%, and power reactor-grade contains 19% or more Pu. Supergrade plutonium , with less than 4% of Pu,

3285-504: The complicated phase diagram are not entirely understood. The α form has a low-symmetry monoclinic structure, hence its brittleness, strength, compressibility, and poor thermal conductivity. Plutonium in the δ ( delta ) form normally exists in the 310 °C to 452 °C range but is stable at room temperature when alloyed with a small percentage of gallium , aluminium , or cerium , enhancing workability and allowing it to be welded . The δ form has more typical metallic character, and

3358-427: The different allotropes vary from 16.00 g/cm to 19.86 g/cm . The presence of these many allotropes makes machining plutonium very difficult, as it changes state very readily. For example, the α form exists at room temperature in unalloyed plutonium. It has machining characteristics similar to cast iron but changes to the plastic and malleable β ( beta ) form at slightly higher temperatures. The reasons for

3431-778: The experience gained from the Rokkasho centrifuge enrichment plant will be a key contribution from JAEA. On April 1, 2016, JAEA transferred some of its laboratories to the National Institute of Radiological Sciences (NIRS), and the NIRS body was renamed to the National Institutes for Quantum and Radiological Science and Technology (QST) which includes existing laboratories of the NIRS. In 2018 JAEA estimated it would need about 1.9 trillion yen ($ 17.1 billion) to decommission 79 facilities over 70 years. The following

3504-440: The fatigue effects as temperature increases above 100 K. Unlike most materials, plutonium increases in density when it melts, by 2.5%, but the liquid metal exhibits a linear decrease in density with temperature. Near the melting point, the liquid plutonium has very high viscosity and surface tension compared to other metals. Plutonium normally has six allotropes and forms a seventh (zeta, ζ) at high temperature within

3577-594: The first atomic bombs. The Fat Man bombs used in the Trinity nuclear test in July 1945, and in the bombing of Nagasaki in August 1945, had plutonium cores . Human radiation experiments studying plutonium were conducted without informed consent , and several criticality accidents , some lethal, occurred after the war. Disposal of plutonium waste from nuclear power plants and dismantled nuclear weapons built during

3650-504: The first self-sustaining chain reaction in a graphite and uranium pile known as CP-1 . Using theoretical information garnered from the operation of CP-1, DuPont constructed an air-cooled experimental production reactor, known as X-10 , and a pilot chemical separation facility at Oak Ridge. The separation facility, using methods developed by Glenn T. Seaborg and a team of researchers at the Met Lab, removed plutonium from uranium irradiated in

3723-568: The first transuranic element neptunium after the planet Neptune , and suggested that element 94, being the next element in the series, be named for what was then considered the next planet, Pluto . Nicholas Kemmer of the Cambridge team independently proposed the same name, based on the same reasoning as the Berkeley team. Seaborg originally considered the name "plutium", but later thought that it did not sound as good as "plutonium". He chose

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3796-491: The fission of uranium-235 are captured by uranium-238 nuclei to form uranium-239; a beta decay converts a neutron into a proton to form neptunium-239 (half-life 2.36 days) and another beta decay forms plutonium-239. Egon Bretscher working on the British Tube Alloys project predicted this reaction theoretically in 1940. Plutonium-238 is synthesized by bombarding uranium-238 with deuterons (D or H,

3869-407: The general formula PuX 3 where X can be F , Cl , Br or I and PuF 4 is also seen. The following oxyhalides are observed: PuOCl, PuOBr and PuOI. It will react with carbon to form PuC , nitrogen to form PuN and silicon to form PuSi 2 . The organometallic chemistry of plutonium complexes is typical for organoactinide species; a characteristic example of an organoplutonium compound

3942-659: The human body due to the 550 atmospheric and underwater nuclear tests that have been carried out, and to a small number of major nuclear accidents . Most atmospheric and underwater nuclear testing was stopped by the Limited Test Ban Treaty in 1963, which of the nuclear powers was signed and ratified by the United States, United Kingdom and Soviet Union . France would continue atmospheric nuclear testing until 1974 and China would continue atmospheric nuclear testing until 1980. All subsequent nuclear testing

4015-531: The letters "Pu" as a joke, in reference to the interjection "P U" to indicate an especially disgusting smell, which passed without notice into the periodic table. Alternative names considered by Seaborg and others were "ultimium" or "extremium" because of the erroneous belief that they had found the last possible element on the periodic table . Hahn and Strassmann, and independently Kurt Starke , were at this point also working on transuranic elements in Berlin. It

4088-449: The metal without the need for a crucible. Cerium is used as a chemical simulant of plutonium for development of containment, extraction, and other technologies. Plutonium is an element in which the 5f electrons are the transition border between delocalized and localized; it is therefore considered one of the most complex elements. The anomalous behavior of plutonium is caused by its electronic structure. The energy difference between

4161-448: The nuclei of heavy hydrogen ) in the following reaction: where a deuteron hitting uranium-238 produces two neutrons and neptunium-238, which decays by emitting negative beta particles to form plutonium-238. Plutonium-238 can also be produced by neutron irradiation of neptunium-237 . Plutonium isotopes undergo radioactive decay, which produces decay heat . Different isotopes produce different amounts of heat per mass. The decay heat

4234-454: The oxidation state and the nature of the acid anion . It is the acid anion that influences the degree of complexing —how atoms connect to a central atom—of the plutonium species. Additionally, the formal +2 oxidation state of plutonium is known in the complex [K(2.2.2-cryptand)] [Pu Cp″ 3 ], Cp″ = C 5 H 3 (SiMe 3 ) 2 . A +8 oxidation state is possible as well in the volatile tetroxide PuO 4 . Though it readily decomposes via

4307-473: The refractory metals chromium , molybdenum , niobium , tantalum, and tungsten, which are soluble in liquid plutonium, but insoluble or only slightly soluble in solid plutonium. Gallium, aluminium, americium, scandium and cerium can stabilize δ-phase plutonium for room temperature. Silicon , indium , zinc and zirconium allow formation of metastable δ state when rapidly cooled. High amounts of hafnium , holmium and thallium also allows some retention of

4380-412: The release of a high-energy helium nucleus, is the most common form of radioactive decay for plutonium. A 5 kg mass of Pu contains about 12.5 × 10 atoms. With a half-life of 24,100 years, about 11.5 × 10 of its atoms decay each second by emitting a 5.157  MeV alpha particle. This amounts to 9.68 watts of power. Heat produced by the deceleration of these alpha particles makes it warm to

4453-499: The sample up to 70% in volume, which in turn flake off as a powder that is pyrophoric . It is radioactive and can accumulate in bones , which makes the handling of plutonium dangerous. Plutonium was first synthesized and isolated in late 1940 and early 1941, by deuteron bombardment of uranium-238 in the 1.5-metre (60 in) cyclotron at the University of California, Berkeley . First, neptunium-238 ( half-life 2.1 days)

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4526-416: The stronger cyclotron at Paris at this point, they would likely have been able to detect plutonium had they tried, albeit in tiny quantities (a few becquerels ). The chemistry of plutonium was found to resemble uranium after a few months of initial study. Early research was continued at the secret Metallurgical Laboratory of the University of Chicago . On August 20, 1942, a trace quantity of this element

4599-402: The touch. Pu due to its much shorter half life heats up to much higher temperatures and glows red hot with blackbody radiation if left without external heating or cooling. This heat has been used in radioisotope thermoelectric generators (see below). The resistivity of plutonium at room temperature is very high for a metal, and it gets even higher with lower temperatures, which

4672-410: The unaided eye. The nuclear properties of plutonium-239 were also studied; researchers found that when it is hit by a neutron it breaks apart (fissions) by releasing more neutrons and energy. These neutrons can hit other atoms of plutonium-239 and so on in an exponentially fast chain reaction. This can result in an explosion large enough to destroy a city if enough of the isotope is concentrated to form

4745-542: The various organs. Hamilton started administering soluble microgram portions of plutonium-239 compounds to rats using different valence states and different methods of introducing the plutonium (oral, intravenous, etc.). Eventually, the lab at Chicago also conducted its own plutonium injection experiments using different animals such as mice, rabbits, fish, and even dogs. The results of the studies at Berkeley and Chicago showed that plutonium's physiological behavior differed significantly from that of radium. The most alarming result

4818-448: The δ phase at room temperature. Neptunium is the only element that can stabilize the α phase at higher temperatures. Plutonium alloys can be produced by adding a metal to molten plutonium. If the alloying metal is reductive enough, plutonium can be added in the form of oxides or halides. The δ phase plutonium–gallium alloy (PGA) and plutonium–aluminium alloy are produced by adding Pu(III) fluoride to molten gallium or aluminium, which has

4891-476: Was conducted underground. Enrico Fermi and a team of scientists at the University of Rome reported that they had discovered element 94 in 1934. Fermi called the element hesperium and mentioned it in his Nobel Lecture in 1938. The sample actually contained products of nuclear fission , primarily barium and krypton . Nuclear fission, discovered in Germany in 1938 by Otto Hahn and Fritz Strassmann ,

4964-500: Was created directly by the bombardment but decayed by beta emission with a half-life of a little over two days, which indicated the formation of element 94. The first bombardment took place on December 14, 1940, and the new element was first identified through oxidation on the night of February 23–24, 1941. A paper documenting the discovery was prepared by the team and sent to the journal Physical Review in March 1941, but publication

5037-624: Was delayed until a year after the end of World War II due to security concerns. At the Cavendish Laboratory in Cambridge , Egon Bretscher and Norman Feather realized that a slow neutron reactor fuelled with uranium would theoretically produce substantial amounts of plutonium-239 as a by-product. They calculated that element 94 would be fissile, and had the added advantage of being chemically different from uranium, and could easily be separated from it. McMillan had recently named

5110-426: Was isolated and measured for the first time. About 50 micrograms of plutonium-239 combined with uranium and fission products was produced and only about 1 microgram was isolated. This procedure enabled chemists to determine the new element's atomic weight. On December 2, 1942, on a racket court under the west grandstand at the University of Chicago's Stagg Field, researchers headed by Enrico Fermi achieved

5183-431: Was synthesized, which then beta-decayed to form the new element with atomic number 94 and atomic weight 238 (half-life 88 years). Since uranium had been named after the planet Uranus and neptunium after the planet Neptune , element 94 was named after Pluto , which at the time was also considered a planet. Wartime secrecy prevented the University of California team from publishing its discovery until 1948. Plutonium

5256-400: Was that there was significant deposition of plutonium in the liver and in the "actively metabolizing" portion of bone. Furthermore, the rate of plutonium elimination in the excreta differed between species of animals by as much as a factor of five. Such variation made it extremely difficult to estimate what the rate would be for human beings. During World War II the U.S. government established

5329-579: Was unknown at the time. Plutonium (specifically, plutonium-238) was first produced, isolated and then chemically identified between December 1940 and February 1941 by Glenn T. Seaborg , Edwin McMillan , Emilio Segrè , Joseph W. Kennedy , and Arthur Wahl by deuteron bombardment of uranium in the 60-inch (150 cm) cyclotron at the Berkeley Radiation Laboratory at the University of California, Berkeley . Neptunium-238

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