Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal with a silver-gray appearance that stains when exposed to air, and forms a blunt layer. when oxidized. Elements usually show six allotropes and four oxidation numbers. It reacts with carbon, halogen, nitrogen, silicon, and hydrogen. When exposed to moist air, it forms oxides and hydrides which can expand the sample by up to 70% by volume, which in turn peels off as a pyrophoric powder. It is radioactive and can accumulate in bone, which makes plutonium handling dangerous.
Plutonium was first produced and isolated on December 14, 1940 by the uranium-238 deuteron bombing within 1.5 meters (60 inches) of cyclotrons at the University of California, Berkeley. The first Neptunium-238 (part-time 2.1 days) was synthesized which then dissolved the beta to form this new element with atomic number 94 and atomic weight of 238 (half 87.7 years). Since uranium is named after the planet Uranus and neptunium after the planet Neptune, element 94 was named after Pluto, which at the time was considered a planet as well. The informal name for plutonium, plute, comes from this name as well. Wartime secrecy prevents them from announcing discovery until 1948. Plutonium is the element with the highest atomic number that occurs in nature. Trace amounts appear in natural uranium-238 deposits when U-238 captures neutrons emitted by decaying other U-238 atoms. Plutonium is much more common on Earth since 1945 as a product of neutron capture and beta decay, where some neutrons released by the fission process convert the uranium-238 nucleus into plutonium-239.
Both plutonium-239 and plutonium-241 are fissile, meaning that they can maintain nuclear chain reactions, leading to applications in nuclear weapons and nuclear reactors. Plutonium-240 exhibits high levels of spontaneous fission, increasing the neutron flux of each sample containing it. The presence of plutonium-240 limits the usefulness of plutonium samples for weapons or their quality as reactor fuel, and the percentage of plutonium-240 determines its level (weapon grade, fuel level, or reactor level). Plutonium-238 has an 88-year half-life and emits alpha particles. It is a heat source in radioisotope thermoelectric generators, used to drive multiple spacecraft. The plutonium isotope is expensive and uncomfortable to separate, so special isotopes are usually produced in special reactors.
Producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II that developed the first atomic bomb. The Fat Man bomb used in the Trinity nuclear test in July 1945, and in the Nagasaki bombing of August 1945, had a plutonium core. Human radiation experiments studying plutonium are done without informed consent, and some critical, some deadly crashes, occur after the war. The disposal of plutonium waste from nuclear power plants and the dismantling of nuclear weapons built during the Cold War is a nuclear proliferation and environmental concern. Other sources of plutonium in the environment come from various nuclear tests on the ground, now banned.
Video Plutonium
Characteristics
Physical properties
Plutonium, like most metals, has a bright silver appearance at first, such as nickel, but is very rapidly oxidized to dull gray, although yellow and olive green are also reported. At room temperature, plutonium is in it? ( alpha ) form. This, the most common structural form of the element (allotropes), is as tough and brittle as gray iron casting unless it is mixed with other metals to make it soft and brittle. Unlike most metals, this is not a good conductor of heat or electricity. It has a low melting point (640 Â ° C) and a very high boiling point (3.228 Â ° C).
Alpha decay, the release of a high-energy helium nucleus, is the most common form of radioactive decay for plutonium. A 5kg mass of 239 Pu contains about 12.5 ÃÆ' - 10 24 atoms. With a half-life of 24,100 years, approximately 11,5 ÃÆ' - 10 12 of the atoms decomposes every second by emitting alpha 5.157 MeV particles. This means power of 9.68 watts. The heat generated by this alpha particle slowing makes it warm to the touch.
Resistivity is a measure of how strongly the material opposes the flow of electric current. The resistivity of plutonium at room temperature is very high for metals, and it is even higher with lower temperatures, which is unusual for metals. This trend continues down to 100à ¢ â,¬Â K, below which resistivity decreases rapidly for fresh samples. The resistivity then begins to increase by about 20  ° K due to radiation damage, to a level determined by the sample isotope composition.
Because of self-irradiation, plutonium fatigues samples throughout its crystal structure, meaning that its regular arrangement of atoms becomes disrupted by time-radiation. Self irradiation can also cause annealing against some of the effects of fatigue as temperatures rise above 100 ° K.
Unlike most materials, plutonium increases the density when it melts, by 2.5%, but the liquid metal shows a decrease in linear density with temperature. Near the melting point, liquid plutonium has a very high viscosity and surface tension compared to other metals.
Allotropes
Plutonium usually has six allotropes and forms the seventh (zeta,?) At high temperatures in a limited pressure range. These allotropes, which are structural modifications or forms of different elements, have very similar internal energies but significantly vary the density and crystal structure. This makes plutonium very sensitive to changes in temperature, pressure, or chemistry, and allows for dramatic volume changes after the phase transition from one allotropic form to another. Different allotropic densities vary from 16.00 g/cm 3 to 19.86 g/cm 3 .
The presence of many of these allotropes makes the plutonium machine extremely difficult, as it is very easily altered. For example, that? shape exists at room temperature in pure plutonium. It has machining characteristics similar to cast iron but turns into plastic and soft? ( beta
Plutonium in? The form ( delta Nuclear splitting
Plutonium is an isotope radioactive actinide, plutonium-239, is one of the three main fissile isotopes (uranium-233 and uranium-235 are the other two); plutonium-241 is also very fissile. To be considered a fissile, atomic isotope nuclei must be able to break or divide when struck by slow moving neutrons and release enough neutrons to maintain a nuclear chain reaction by further breaking the nucleus.
Pure plutonium-239 may have a doubling factor (k eff ) greater than one, which means that if the metal is present in sufficient quantities and with the appropriate geometry (for example, a ball of sufficient size), it can form a critical mass. During fission, a small fraction of the nuclear binding energy, which holds the nucleus together, is released as a large amount of electromagnetic and kinetic energy (many of the latter are quickly converted into thermal energy). The cleavage of one 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 plutonium-240 isotope in the sample limits the potential of its nuclear bomb, since plutonium-240 has a relatively high spontaneous fission rate (~ 440 fissions per second per gram - more than 1,000 neutrons per second per gram), increasing the neutron-level background and thus increase the risk of predetonation. Plutonium is identified as an armaments class, fuel level, or reactor class based on the percentage of plutonium-240 it contains. Plutonium-class weapons contain less than 7% plutonium-240. Plutonium fuels contain from 7% to less than 19%, and the reactor class contains 19% or more of plutonium-240. Supergrade plutonium, with less than 4% plutonium-240, is used in US Navy weapons stored near ships and submarines, due to its lower radioactivity. The plutonium-238 isotope is not fissile but can undergo nuclear fission easily with fast neutrons as well as alpha decay.
Isotopes and nukleosynthesis
Twenty radioactive isotopes of plutonium have been characterized. Longest life is plutonium-244, with a half-life of 80.8 million years, plutonium-242, with a half-life of 373,300 years, and plutonium-239, with a half-life of 24,110 years. All remaining radioactive isotopes have a half-life of less than 7,000 years. This element also has eight metastable states, although all have half-lives of less than one second.
Isotopes are known from the plutonium range in mass quantities from 228 to 247. The major decay modes of isotopes with lower mass numbers of the most stable isotope, plutonium-244, are spontaneous fission and alpha emissions, mostly forming uranium (92 protons) and neptunium (93 protons) of isotopes as decay products (ignoring the female core made by the fission process). The main decay modes for isotopes with mass numbers higher than plutonium-244 are beta emissions, mostly forming the americium isotope (95 protons) as decay products. Plutonium-241 is the parent isotope of the decay series of neptunium, decomposing to americium-241 through beta emission.
Plutonium-238 dan 239 adalah isotop yang paling banyak disintesis. Plutonium-239 disintesis melalui reaksi berikut menggunakan uranium (U) dan neutron (n) melalui peluruhan beta (? - ) dengan neptunium (Np) sebagai perantara:
Neutrons of uranium-235 fission are captured by uranium-238 nuclei to form uranium-239; beta decay converts neutrons into protons to form neptunium-239 (half-life of 2.36 days) and other beta decay forms plutonium-239. Egon Bretscher who worked on the British Tube Alloys project predicted this reaction theoretically in 1940.
In this process, the deuterons that strike uranium-238 produce two neutrons and neptunium-238, which spontaneously decays by emitting beta-negative particles to form plutonium-238.
Rotting heat and fission properties
The isotopes of plutonium undergo radioactive decay, which results in the heat of decay. Different isotopes produce different amounts of heat per mass. Heat decay is usually listed as watt/kilogram, or milliwatt/gram. In larger pieces of plutonium (eg gunholes) and inadequate heat transfer, the resulting self-heating may be significant. All isotopes produce weak gamma radiation in decay.
Compounds and chemistry
At room temperature, pure silver plutonium but stains the stain when it is oxidized. This element displays four common ionic oxidation states in aqueous solutions and one that is rare:
- Pu (III), such as Pu 3 (blue lavender)
- Pu (IV), such as Pu 4 (yellow brown)
- Pu (V), such as PuO 2 (pink)
- Pu (VI), such as PuO 2
2 (orange pink) - Pu (VII), such as PuO 3 -
< sub style = "font-size: inherit; line-height: inherit; vertical-align: baseline"> 5 (green) - rarely heptavalent ions.
The color indicated by the plutonium solution depends on the oxidation state and the nature of the acid anion. It is an acid anion that affects the degree of complexity - how the atoms are connected to the central atom - of the species of plutonium. In addition, the formal oxidation state of plutonium is known in the complex [K (2.2.2-cryptand)] [Pu II Cp? 3 ], Cp? = C 5 H 3 (SiMe 3 ) 2 .
Metallic plutonium is produced by reacting plutonium tetrafluoride with barium, calcium or lithium at 1200 ° C. It is attacked by acid, oxygen, and vapor but not by alkali and readily soluble in concentrated hydroiodic, hydroiodic and perchloric acid. Liquid metal must be stored in a vacuum or inert atmosphere to avoid reaction with air. At 135 ° C the metal will burn in air and will explode if placed in carbon tetrachloride.
Plutonium is a reactive metal. In moist air or wet argon, metals quickly oxidize, producing a mixture of oxides and hydrides. If the metal is exposed long enough to a small amount of water vapor, the surface layer of PuO powder 2 is formed. Also formed are plutonium hydrides but excess moisture only forms PuO 2 .
Plutonium exhibits a very large reaction rate, and is reversible with pure hydrogen, forming plutonium hydride. It also reacts 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 halogens, giving rise to a compound of the general formula PuX 3 where X can be F, Cl, Br or I and PuF 4 are also visible. The following oxidases are observed: PuOCl, PuOBr and PuOI. It will react with carbon to form PuC, nitrogen to form PuN and silicon to form PuSi 2 .
Specific plutonium, hydride and oxide powders such as Pu 2 O 3 are pyrophoric, meaning they can ignite spontaneously at room temperature and are therefore handled in a dry, inert atmosphere of nitrogen or argon. Plutonium bulk only burns when heated above 400 ° C. Pu 2 O 3 spontaneously heats up and turns into PuO 2 , which is stable in air is dry, but reacts with moisture when heated.
The crucible used to contain plutonium must be able to withstand its very reduced properties. Refractory metals such as tantalum and tungsten along with more stable oxides, borides, carbides, nitrides and silicides can tolerate this. Melt in an electric arc furnace can be used to produce small ingots of metal without the need for a container.
Cerium is used as a plutonium chemical simulant for the development of containment, extraction, and other technologies.
Electronic structure
Plutonium is the element in which the 5f electron is the transition boundary between delocalized and localized; it is therefore regarded as one of the most complex elements. The behavior of plutonium anomaly is caused by its electronic structure. The energy difference between sections 6d and 5f is very low. The size of the 5f shell is just enough to allow the electrons to form bonds in the lattice, at the boundary between localized behavior and bonding. The proximity of the energy level leads to several low-energy electron configurations with almost the same energy levels. This leads to the competition of 5f n 7s 2 and 5f n-1 6d 1 7s 2 configuration, which causes the complexity of its chemical behavior. The directional property of the 5f orbitals is responsible for the directional covalent bonding in molecules and plutonium complexes. Alloy
Plutonium can form alloys and intermediates with most other metals. Exceptions include lithium, sodium, potassium, rubidium and cesium from alkali metals; and magnesium, calcium, strontium, and barium of alkaline earth metals; and europium and ytterbium of rare earth metals. Some exceptions include chromium, molybdenum, niobium, tantalum, and tungsten, which are soluble in liquid plutonium, but not soluble or only slightly soluble in solid plutonium. Gallium, aluminum, americium, scandium and cerium can stabilize? phase plutonium for room temperature. Silicon, indium, zinc and zirconium allow the formation of metastable? state when cooled quickly. A large number of hafnium, holmium and thallium also allow retention of? phase at room temperature. Neptunium is the only stabilizing element? phase at higher temperatures.
Plutonium alloys can be produced by adding metal to liquid plutonium. If the alloy metal is reductive enough, plutonium may be added in the form of oxide or halide. That? plutonium-gallium phase and plutonium-aluminum alloys are produced by adding plutonium (III) fluoride to gallium or liquid aluminum, which has the advantage of avoiding direct contact with highly reactive plutonium metals.
- Plutonium-gallium used to stabilize? phase plutonium, avoid? -phase and? -? related issues. Its main use is in nuclear weapon blast holes.
- Plutonium-aluminum is an alternative to Pu-Ga alloys. That is the original element to consider? phase stabilization, but its tendency to react with alpha particles and release neutrons reduces their usefulness for nuclear weapons pits. Plutonium aluminum alloys can also be used as nuclear fuel components. The alloy
- Plutonium-gallium-cobalt (PuCoGa 5 ) is an unconventional superconductor, showing superconductivity below 18.5 K, an order of magnitude higher than the highest between heavy fermions system, and has a large critical current. Alloys
- Plutonium-zirconium can be used as nuclear fuel.
- Plutonium-cerium and plutonium-cerium-cobalt alloys are used as nuclear fuel.
- Plutonium-uranium , with about 15-30 mol.% plutonium, can be used as a nuclear fuel for fast-breeding reactors. The pyrophoric nature and high susceptibility to corrosion to the point of self-igniting or disintegration after exposure to air require alloying with other components. The addition of aluminum, carbon or copper does not increase the apparent disintegration rate, zirconium and iron alloys have better corrosion resistance but they are destroyed in months in the air as well. The addition of titanium and/or zirconium significantly increases the melting point of the alloy.
- Plutonium-uranium-titanium and plutonium-uranium-zirconium were investigated for use as nuclear fuel. The addition of a third element improves corrosion resistance, reduces flammability, and enhances ductility, manufacturing ability, strength, and thermal expansion. Plutonium-uranium-molybdenum has the best corrosion resistance, forming an oxide protective film, but titanium and zirconium are preferred for physical reasons.
- Thorium-uranium-plutonium is investigated as a nuclear fuel for fast-breeding reactors.
Genesis
The number of traces of plutonium-238, plutonium-239, plutonium-240, and plutonium-244 can be found in nature. Small traces of plutonium-239, parts per trillion, and decay products are naturally found in some concentrated uranium ores, such as the natural nuclear fission reactor in Oklo, Gabon. The plutonium-239 to uranium ratio of the Lake Mine uranium mine ranges from 2.4 ÃÆ' - 10 -12 to 44 Ã R - 10 -12 . This trace number 239 Pu comes in the following mode: on rare occasions, 238 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 attacks another nucleus of 238 U, this atom is absorbed by the atom, which becomes 239 U. With a relatively short half-life, 239 U decays to 239 Np, which decomposes into 239 Pu. Finally, a very small amount of plutonium-238, attributed to the extremely rare, double-decayed beta of uranium-238, has been found in natural uranium samples.
Because of the relatively long half-life of about 80 million years, it is suggested that plutonium-244 occurs naturally as a primordial nuclide, but the initial detection report can not be confirmed. However, its long beak ensures circulation throughout the solar system before its extinction, and indeed, evidence of spontaneous spasm <244> Pu has become extinct in meteorites. The earlier presence of 244 Pu in the early Solar System has been confirmed, as it manifests itself today as the excess of its daughter, either 232 Th (from the alpha decay path) or the xenon isotope (from spontaneous fission). The latter is generally more useful, since thorium and plutonium chemistry are somewhat similar (both are tetravalent dominated) and hence thorium excess will not be strong evidence that some of these are formed as plutonium girls. 244 Pu has the longest half-life of all transuranic nuclides and is only produced in r processes on supernovae and colliding neutron stars; when the cores are removed from these events at high speed to reach Earth, 244 Pu alone among transuranic nuclides has a half-life long enough to survive on the way, and hence a small footprint of interstellar life 244 Pu has been found on the deep ocean floor. Because 240 Pu also occurs in the decay chain 244 Pu, it should also be present in secular equilibrium, albeit in smaller quantities.
The minute footprint of plutonium is usually found in the human body because of the 550 atmospheric and underwater nuclear tests that have been performed, and for a small number of major nuclear accidents. Much of atmospheric and underwater nuclear testing was stopped by the Limited Test Ban Treaty in 1963, signed and ratified by the United States, Britain, the Soviet Union, and other countries. Advanced atmospheric nuclear weapons trials since 1963 by non-treaty countries including China (atomic bomb test over the Gobi Desert in 1964, hydrogen bomb test in 1967, and further tests), and France (recent tests in the 1990s an). Due to deliberately made for nuclear weapons and nuclear reactors, plutonium-239 is the most abundant plutonium isotope so far.
Maps Plutonium
History
Discovery
Enrico Fermi and a team of scientists at the University of Rome reported that they had discovered 94 elements in 1934. Fermi called the hesperium element and mentioned it in the Nobel Lecture in 1938. The actual sample is a mixture of barium, krypton, and other elements , but this was not known at the time. Nuclear division was discovered in Germany in 1938 by Otto Hahn and Fritz Strassmann. The fission mechanism was then explained theoretically by Lise Meitner and Otto Frisch.
Plutonium (in particular, plutonium-238) was first produced and isolated on December 14, 1940, and chemically identified on February 23, 1941, by Glenn T. Seaborg, Edwin McMillan, Joseph W. Kennedy, and Arthur Wahl by deuteron bombardment of uranium. in a 60-inch (150 cm) cyclotron at the Berkeley Radiation Laboratory at the University of California, Berkeley. In the 1940 trials, neptunium-238 was made directly by bombardment, but was destroyed by beta emission with a half-life of slightly more than two days, indicating the formation of element 94.
A paper documenting the discovery was prepared by the team and sent to the journal Physical Review in March 1941, but the publication was postponed 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 uranium-induced slow uranium reactors would theoretically produce large amounts of plutonium-239 as a by-product. They calculated that element 94 would be fissile, and had an additional advantage that was chemically different from uranium, and could easily be separated from it.
McMillan recently named the first transuranic elemental neptunium after the planet Neptune, and suggested that element 94, which is the next element in the series, is named for what would later be considered the next planet, Pluto. Nicholas Kemmer from the Cambridge team independently proposed the same name, based on the same reasons as the Berkeley team. Seaborg was originally considered the name of "plutium", but later thought that it did not sound as good as "plutonium". He chose the letter "Pu" as a joke, referring to "P U" to show a very disgusting smell, which passed unannounced to the periodic table. Alternative names considered by Seaborg and others are "ultimium" or "extreme" because of the erroneous belief that they have found the last possible element on the periodic table.
Initial research
Chemistry of plutonium was found to resemble uranium after several months of initial studies. Initial research was continued at the University of Chicago's Secret Metallurgy Laboratory. On August 20, 1942, a small number of these elements were isolated and measured for the first time. About 50 micrograms of plutonium-239 combined with uranium and fission products are produced and only about 1 microgram is isolated. This procedure allows the chemist to determine the atomic weight of the new element. On December 2, 1942, in a court rack beneath the western stands at Stagg Field Chicago University, researchers led by Enrico Fermi achieved the first self-chain reaction in graphite and uranium known as CP-1. Using the theoretical information gathered from CP-1 operations, DuPont built an air-cooled experimental production plant, known as X-10, and a pilot chemical separation facility at Oak Ridge. The separation facility, using a method developed by Glenn T. Seaborg and a team of researchers at Met Lab, removes plutonium from illuminated uranium in the X-10 reactor. Information from CP-1 is also useful for Met Lab scientists designing water-cooled plutonium production reactors for Hanford. Construction on site began in mid-1943.
In November 1943 some plutonium trifluoride was reduced to make the first sample of plutonium metal: some micrograms of metal beads. Enough plutonium is produced to make it the first synthetic element visible to the naked eye.
The nuclear properties of plutonium-239 are also studied; The researchers found that when struck by the neutrons it breaks apart (fission) by releasing more neutrons and energy. These neutrons can hit other atoms from plutonium-239 and so on in very fast chain reactions. This can produce a large enough explosion to destroy the city if enough isotopes are concentrated to form a critical mass.
During the early stages of the study, animals were used to study the effects of radioactive substances on health. These studies began in 1944 at the University of California at the Berkeley Radiation Laboratory and were conducted by Joseph G. Hamilton. Hamilton is looking to answer the question of how plutonium will vary in the body depending on the mode of exposure (oral consumption, inhalation, skin absorption), retention rate, and how plutonium will be repaired in tissues and distributed among various organs. Hamilton began to provide dissolved micrograms of plutonium-239 compounds to mice using different valence states and different methods for introducing plutonium (oral, intravenous, etc.). Finally, the lab in Chicago also experimented with plutonium injection itself using different animals such as mice, rabbits, fish, and even dogs. The results of the study at Berkeley and Chicago show that the physiological behavior of plutonium differs significantly from radium. The most alarming result is that there is significant deposition of plutonium in the liver and in the "active metabolic" part of the bone. Furthermore, the extent of plutonium elimination in excreta varies between animal species by a factor of five. Such variations make it very difficult to estimate what level it is for humans.
Production during the Manhattan Project
During World War II the US government established the Manhattan Project, which was tasked with developing an atomic bomb. The three major research sites and production of the project are the plutonium production facilities in what is now the Hanford Site, the uranium enrichment facility at Oak Ridge, Tennessee, and the weapons research and design laboratory, now known as Los Alamos National Laboratory.
The first production reactor to make plutonium-239 was the X-10 Graphite Reactor. It started online in 1943 and was built at a facility at Oak Ridge which later became Oak Ridge National Laboratory.
In January 1944, the workers laid the foundations for the first chemical separation building, T Plant located at 200-West. Both the T Plant and the facilities of his 200-West sister, U Plant, were completed in October. (U Plant is only used for training during the Manhattan Project.) The 200-East separation building, B Plant, was completed in February 1945. The second facility planned for 200-East was canceled. Nicknamed the Queen Marys by the builders, the separating structures have a structure like an 800-foot-long, 65-foot-high, 80-foot-high gorge that contains forty processing pools. The interior has a daunting quality as the operator behind the remote control manipulation equipment seven feet from the concrete shield by looking through the television monitor and periscope of the top gallery. Even with large concrete caps on process ponds, precautionary measures against radiation exposure are needed and affect all aspects of plant design.
On April 5, 1944, Emilio SegrÃÆ'¨ at Los Alamos received the first sample of reactor-produced plutonium from Oak Ridge. Within ten days, he found that the plutonium produced by the reactor had a higher concentration of plutonium-240 isotope than the plutonium produced by cyclotron. Plutonium-240 has a high spontaneous fission rate, increasing the overall neutron level of the plutonium sample. The original gun-type plutonium weapon, code-named "Thin Man", must be abandoned as a result - an increase in the number of spontaneous neutrons means that nuclear pre-detonation may fail.
The entire plutonium weapon design effort at Los Alamos was soon transformed into a more complicated explosive device, code-named "Fat Man". With implosi weapons, plutonium is compressed into high density with an explosive lens - a task that is technically more frightening than a simple weapon type design, but it needs to use plutonium for weapon purposes. Uranium enriched, on the other hand, can be used by any method.
Construction of the Hanford Reactor B, the first industrial-sized nuclear reactor for material production purposes, was completed in March 1945. Reactor B produced fissile material for the plutonium weapons used during World War II. B, D and F are early reactors built at Hanford, and six additional plutonium-producing reactors are built later on site.
At the end of January 1945, very pure plutonium had further concentrations in a finished chemical insulation building, where the remaining dirt was removed. Los Alamos received the first plutonium from Hanford on 2 February. While it is not yet clear that enough plutonium could be produced for use in bombs by the end of the war, Hanford in early 1945 operated. Only two years have passed since Colonel Franklin Matthias first established a temporary headquarters on the banks of the Columbia River.
According to Kate Brown, the plutonium production plant at Hanford and Mayak in Russia, for four decades, "both released more than 200 million radioactive isotope cells to the surrounding environment - twice the amount spent in the Chernobyl disaster in each instance." Most of these radioactive contaminations over the years are part of normal operation, but unexpected accidents happen and crop management keeps this a secret, as pollution continues.
In 2004, a safe was discovered during a funeral trench dig at Hanford nuclear site. Inside the safe there are a variety of items, including a large glass bottle containing a whitish porridge which is then identified as the oldest sample of known weapon-grade plutonium. The isotope analysis by the Pacific Northwest National Laboratory showed that plutonium in the bottle was produced at the X-10 Graphite Reactor at Oak Ridge during 1944.
Trinity and Fat Man atomic bomb
The first atomic bomb test, codenamed "Trinity" and detonated on July 16, 1945, near Alamogordo, New Mexico, used plutonium as its fissile material. The design of the "gadget" explosion, as a Trinity device codenamed, uses a conventional explosive lens to push the ball of plutonium into a supercritical mass, simultaneously bombarded with neutrons of "Urchin", an initiator made of polonium. and beryllium (the source of neutrons: (?, n) reactions). Together, this ensures chain reaction and explosion. The overall weapon weighed more than 4 tons, although it only uses 6.2 kg of plutonium in its core. About 20% of the plutonium used in Trinity weapons is fissional, producing explosions with energy equivalent to about 20,000 tons of TNT.
The identical design used in the "Fat Man" atomic bomb dropped in Nagasaki, Japan, on August 9, 1945, killed 35,000-40,000 people (mostly industrial workers) and destroyed 68% -80% of war production in Nagasaki.. Only after the announcement of the first atomic bomb was the existence and name of plutonium known to the public by the Smyth Report of the Manhattan Project.
Cold War use and waste
The large stock of weapon-grade plutonium was built by the Soviet Union and the United States during the Cold War. The US reactor at Hanford and the Savannah River Site in South Carolina produces 103 tons, and an estimated 170 tons of military-level plutonium are produced in the Soviet Union. Every year about 20 tons of elements are still being produced as a by-product of the nuclear power industry. A total of 1,000 tons of plutonium may be in storage with more than 200 tons which are either inside or extracted from nuclear weapons. SIPRI estimates the world's plutonium stock in 2007 to be about 500 tons, divided equally between weapons and civilian stocks.
Radioactive contamination in the Rocky Flats Plant was mainly produced from two major plutonium fires in 1957 and 1969. A much lower concentration of radioactive isotopes was expelled throughout the operational life of the plant from 1952 to 1992. The wind used from the plant brought air contamination to the south and east. , to the populated areas of northwest Denver. Denver area contamination by plutonium from fires and other sources was not reported openly until the 1970s. According to a 1972 study authored by Edward Martell, "In the more populated areas of Denver, Pu pollution rates on surface soils are several times the fall," and plutonium contamination "to the east of the Rocky Flats mill ranges hundreds of times from nuclear testing ". As noted by Carl Johnson at Ambio, "The exposure of a large population in the Denver area to plutonium and other radionuclides in tailings exhaust from factory date back to 1953." The production of weapons at the Rocky Flats plant was suspended after the combined FBI and EPA attacks in 1989 and the years of protest. The plant has been closed, with the building destroyed and completely removed from the site.
In the US, some of the extracted plutonium from dismantled nuclear weapons is melted to form a two ton log of plutonium oxide glass. The glass is made of borosilicate mixed with cadmium and gadolinium. This log is planned to be wrapped in stainless steel and stored as much as 4 km (2 mi) underground in a borehole that will be refilled with concrete. The US plans to store plutonium in this way at the Yucca Mountain nuclear waste repository, which is about 100 miles (160 km) northeast of Las Vegas, Nevada.
On March 5, 2009, Energy Secretary Steven Chu told the Senate hearing "the location of Yucca Mountain is no longer seen as an option to store reactor waste". Beginning in 1999, the military-generated nuclear waste is being buried at the Waste Isolation Pilot Plant in New Mexico.
In the Presidential Memorandum of 29 January 2010, President Obama formed the Blue Ribbon Commission on the Future of Nuclear America. In its final report, the Commission proposed to develop a comprehensive strategy to be followed, including:
- "Recommendation # 1: The United States must undertake an integrated nuclear waste management program that leads to the timely development of one or more permanent permanent geological facilities for safe disposal of spent nuclear fuel and high level nuclear waste."
Medical experiments
During and after the end of World War II, scientists working on the Manhattan Project and other nuclear weapons research projects conducted studies on the effects of plutonium on laboratory animals and human subjects. Animal studies have found that several milligrams of plutonium per kilogram of tissue is a lethal dose.
In the case of human subjects, this involves an injection solution containing (typically) five micrograms of plutonium to a hospital patient who is considered seriously ill, or has a life expectancy of less than ten years due to age or chronic disease. This was reduced to one microgram in July 1945 after animal studies found that the way plutonium is distributed in bones is more harmful than radium. Most of the subjects, Eileen Welsome says, are the poor, helpless, and sick.
From 1945 to 1947, eighteen human test subjects were injected with plutonium without consent. This test is used to create a diagnostic tool to determine the absorption of plutonium in the body to develop safety standards for working with plutonium. Ebb Cade is a participant who does not want to be involved in a medical experiment involving the injection of 4.7 micrograms of Plutonium on April 10, 1945 in Oak Ridge, Tennessee. This trial was under the supervision of Harold Hodge. Another experiment directed by the United States Atomic Energy Commission and the Manhattan Project continued into the 1970s. The Plutonium Files tells the life of the subject of a secret program by calling everyone involved and discussing ethical and medical research conducted secretly by scientists and doctors. This episode is now considered a serious violation of medical ethics and the Hippocratic Oath.
The government covered up most of these radiation accidents until 1993, when President Bill Clinton ordered policy changes and federal agencies then made available relevant records. The resulting inquiry was conducted by the Presidential Advisory Committee on Human Radiation Experiments, and it revealed a lot of material about human plutonium research. The committee issued a controversial 1995 report that said "mistakes were made" but did not condemn those who made mistakes.
Apps
Explosives
The isotope plutonium-239 is a key fissile component in nuclear weapons, because of its easy fission and availability. Wrapping the plutonium bomb hole in the tamper (optional layer of solid material) reduces the amount of plutonium needed to reach critical mass by reflecting back neutrons that return to the core of plutonium. This reduces the amount of plutonium needed to achieve criticality from 16 kg to 10 kg, which is a sphere with a diameter of about 10 centimeters (4 inches). This critical mass is about a third of that for uranium-235.
The Fat Man plutonium bomb uses explosive plutonium compression to obtain a higher than usual density, combined with a central neutron source to initiate the reaction and increase efficiency. So only 6.2 kg of plutonium is required for explosive results equivalent to 20 kilotons of TNT. Hypothetically, as little as 4 kg of plutonium - and perhaps even less - can be used to make a single atomic bomb using a very sophisticated assembly design.
Mixed oxide fuel
The use of nuclear fuel from normal light-water reactors contains plutonium, but is a mixture of plutonium-242, 240, 239 and 238. This mixture is not sufficiently enriched for efficient nuclear weapons, but can be used once as a MOX fuel. The unintentional arrest of neutrons causes the amount of plutonium-242 and 240 to grow every time the plutonium is irradiated in a reactor with a low-speed "thermal" neutron, so that after the second cycle, plutonium can only be consumed by a fast neutron reactor. If fast neutron reactors are not available (normal case), excessive plutonium is usually discarded, and forms the longest component of nuclear waste. The desire to consume this plutonium and other transuranic fuels and reduce waste radiotoxicity is a common reason given by nuclear engineers to make fast neutron reactors.
The most common chemical processes, PUREX ( P lutonium- UR anium EX traction) reprocess nuclear fuel to extract plutonium and usable uranium to form a mixed oxide fuel (MOX) for reuse in a nuclear reactor. Plutonium-grade weapons can be added to the fuel mixture. MOX fuels are used in light water reactors and comprise 60 kg of plutonium per tonne of fuel; after four years, three quarters of plutonium was burned (converted into other elements). The breeder reactor is specifically designed to create a more fissionable material than they consume.
MOX fuels have been used since the 1980s, and are widely used in Europe. In September 2000, the United States and the Russian Federation signed a Plutonium Management and Disposition Agreement each agreeing to dispose of 34 tonnes of weapons-grade plutonium. The US Department of Energy plans to dispose 34 tonnes of weapons-grade plutonium in the United States before the end of 2019 by converting plutonium into MOX fuels to be used in commercial nuclear power reactors.
MOX fuel increases the total fuel amount. The fuel rods are reprocessed after three years of use to dispose of waste products, which by then account for 3% of the total weight of the stem. Each of the uranium isotope or plutonium produced during the three years is left and the stem back into production. The presence of up to 1% gallium per mass in weapons-grade plutonium alloys has the potential to disrupt the long-term operation of light water reactors.
Plutonium recovered from spent fuel reactors poses little danger of proliferation, due to excessive contamination with plutonium-240 non-fissile and plutonium-242. Isotope separation is not feasible. A special reactor operates at a very low burnup (hence the new plutonium-239 minimally exposed to additional neutrons causing it to be converted into heavier plutonium isotopes) is generally required to produce materials suitable for use in efficient nuclear weapons. While "weapon-grade" plutonium is defined to contain at least 92% plutonium-239 (of total plutonium), the United States has managed to detonate devices under 20Kt using plutonium that is believed to contain only about 85% plutonium-239, called plutonium "fuel-class ". Plutonium "reactor-grade" produced by ordinary LWR combustion cycles typically contains less than 60% Pu-239, with 30% Pu-240/Pu-242 parasites, and 10-15% Pu-241 fissile. It is not known whether devices using plutonium obtained from recoverable civil nuclear waste could be detonated, but the device could hypothetically fail and spread radioactive material to large urban areas. The IAEA conservatively classifies plutonium from all isotopic vectors as "direct use" materials, ie, "nuclear material that can be used for the manufacture of nuclear explosive components without transmutation or further enrichment".
Resources and heat
The plutonium-238 isotope has a half-life of 87.74 years. It emits large amounts of heat energy with low levels of both gamma/photon rays and spontaneous neutron/particle rays. Being an alpha transmitter, it combines high energy radiation with low penetration and thus requires minimal shielding. A piece of paper can be used to protect the alpha particles emitted by plutonium-238. One kilogram of isotopes can produce about 570 watts of heat.
This characteristic makes it suitable for power generation for devices that must function without direct maintenance for a time span that approaches human life. It is therefore used in radioisotope thermoelectric generators and radioisotope heating units such as those in the Cassini, Voyager, Galileo and New Horizons space probe, and Curiosity Mars rover.
The twin spacecraft Voyager was launched in 1977, each containing a 500 watt plutonium resource. More than 30 years later, each source still produces about 300 watts which allows limited operation of each spacecraft. The previous version of the same technology supported five Apollo Lunar Surface Experiment Packages, starting with Apollo 12 in 1969.
Plutonium-238 has also been successfully used to provide artificial pacemaker, to reduce the risk of recurrent surgery. It has been largely replaced by lithium-based primary cells, but in 2003 there was somewhere between 50 and 100 plutonium-powered pacemakers that were still planted and working in surviving patients. Plutonium-238 was studied as a way to provide additional heat for scuba diving. Plutonium-238 mixed with beryllium was used to produce neutrons for research purposes.
Precautions
Toxicity
There are two aspects of the harmful effects of plutonium: radioactivity and the effects of heavy metal toxins. Isotopes and plutonium compounds are radioactive and accumulate in the bone marrow. Contamination by plutonium oxide has been generated from nuclear disasters and radioactive incidents, including military nuclear accidents in which nuclear weapons have been burned. The study of the effects of this smaller release, as well as the poisonous disease of radiation and death after the atomic bombings of Hiroshima and Nagasaki, has provided much information about the dangers, symptoms and prognosis of radiation poisoning, which in most cases Hibakusha/Japanese survivors are unrelated with direct plutonium exposure.
During the decay of plutonium, three types of radiation are released - alpha, beta, and gamma. Alpha, beta, and gamma radiation are all forms of ionizing radiation. Acute or long-term exposure carries serious harm to health outcomes including radiation, genetic, cancer and death. The danger increases with the amount of exposure. Alpha radiation can travel only a short distance and can not travel through the outer layer of dead skin. Radiation beta can penetrate human skin, but can not penetrate the whole body. Gamma radiation can penetrate the entire body. Although alpha radiation can not penetrate the skin, the inhaled or inhaled plutonium does not irradiate the internal organs. Alpha particles produced by inhaled plutonium have been found to cause lung cancer in a group of European nuclear workers. The skeleton, in which plutonium accumulates, and the liver, where it is collected and concentrated, is at risk. Plutonium is not absorbed into the body efficiently when ingested; only 0.04% of plutonium oxide is absorbed after consumption. Plutonium absorbed by the body is excreted very slowly, with a biological half-life of 200 years. Plutonium is only through cell membranes and intestinal boundaries, so the absorption by consumption and incorporation into the bone structure takes place very slowly.
Plutonium is more dangerous when inhaled than when ingested. The risk of lung cancer increases after total radiation doses equivalent to inhaled plutonium exceeds 400 mSv. The US Department of Energy estimates that the lifetime risk of cancer from inhaling 5,000 plutonium particles, each about 3 Âμm wide, becomes 1% above the US average. Ingestion or large inhalation may cause acute radiation poisoning and possible death. But no human is known to have died by inhaling or swallowing plutonium, and many people have the amount of plutonium in their bodies.
Theory of "hot particles" d
Source of the article : Wikipedia
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