1.
Ampoule
–
An ampoule is a small sealed vial which is used to contain and preserve a sample, usually a solid or liquid. Ampoules are commonly made of glass, although plastic ampoules do exist, modern ampoules are most commonly used to contain pharmaceuticals and chemicals that must be protected from air and contaminants. They are hermetically sealed by melting the thin top with an open flame, if properly done, this last operation creates a clean break without any extra glass shards or slivers, but the liquid or solution may be filtered for greater assurance. The space above the chemical may be filled with a gas before sealing. The walls of glass ampoules are usually sufficiently strong to be brought into a glovebox without any difficulty, historically ampoules were used to contain a small sample of a persons blood after death, which was entombed alongside them in many Christian catacombs. It was originally believed that only martyrs were given this burial treatment, an ampoule, allegedly dating back to the year 305 and filled with the blood of Saint Januarius, bishop of Benevento, has been kept for centuries in the Cathedral at Naples. Another well known ampoule is the Holy Ampulla which held the oil for the coronation of the French monarchs. The oil was allegedly passed down from the time of Clovis I, it was kept for a time in the tomb of Saint Remigius and later in the Cathedral of Notre-Dame, Reims. An order of knights named after the ampoule was created for the coronation of kings to have saved and was used in coronation of Charles X. Modern glass ampoules are produced industrially from short lengths of tubing, shaped by heating with gas torches. Computer vision techniques are employed for quality control. The filling and sealing of ampoules may be done by automated machinery on a scale, or by hand in small-scale industries. Blank ampoules can be purchased from scientific supply houses and sealed with a small gas torch. This forms a membrane allowing someone to turn the open ampule upside down without spilling, a Schlenk line may be used for sealing under inert atmospheres. Ampoules are common practice as containers of low frequency RFID tags and these are used mainly for tagging animals, such as dogs for identification. Ampoules often have colored rings of paint or enamel around their necks, color coding of modern ampoules is done during the manufacturing process. A machine paints colored rings on the ampoule shortly after it has been sealed, the rings are made of a substance that is readable by other machines. These color codes identify the substance inside the ampoule so that it does not need to be tested to verify the contents, the machine-readable color codes allow for accurate handling of the substance for the purposes of storage, labeling, and secondary packaging
2.
Atomic number
–
The atomic number or proton number of a chemical element is the number of protons found in the nucleus of an atom of that element. It is identical to the number of the nucleus. The atomic number identifies a chemical element. In an uncharged atom, the number is also equal to the number of electrons. The atomic number Z, should not be confused with the mass number A and this number of neutrons, N, completes the weight, A = Z + N. Atoms with the atomic number Z but different neutron numbers N. Historically, it was these atomic weights of elements that were the quantities measurable by chemists in the 19th century. Only after 1915, with the suggestion and evidence that this Z number was also the nuclear charge, loosely speaking, the existence or construction of a periodic table of elements creates an ordering of the elements, and so they can be numbered in order. Dmitri Mendeleev claimed that he arranged his first periodic tables in order of atomic weight, however, in consideration of the elements observed chemical properties, he changed the order slightly and placed tellurium ahead of iodine. This placement is consistent with the practice of ordering the elements by proton number, Z. A simple numbering based on periodic table position was never entirely satisfactory and this central charge would thus be approximately half the atomic weight. This proved eventually to be the case, the experimental position improved dramatically after research by Henry Moseley in 1913. To do this, Moseley measured the wavelengths of the innermost photon transitions produced by the elements from aluminum to gold used as a series of movable anodic targets inside an x-ray tube. The square root of the frequency of these photons increased from one target to the next in an arithmetic progression and this led to the conclusion that the atomic number does closely correspond to the calculated electric charge of the nucleus, i. e. the element number Z. Among other things, Moseley demonstrated that the series must have 15 members—no fewer. After Moseleys death in 1915, the numbers of all known elements from hydrogen to uranium were examined by his method. There were seven elements which were not found and therefore identified as still undiscovered, from 1918 to 1947, all seven of these missing elements were discovered. By this time the first four transuranium elements had also been discovered, in 1915 the reason for nuclear charge being quantized in units of Z, which were now recognized to be the same as the element number, was not understood
3.
Nuclear weapon
–
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from small amounts of matter. The first test of a bomb released the same amount of energy as approximately 20,000 tons of TNT. The first thermonuclear bomb test released the same amount of energy as approximately 10 million tons of TNT, a thermonuclear weapon weighing little more than 2,400 pounds can produce an explosive force comparable to the detonation of more than 1.2 million tons of TNT. A nuclear device no larger than traditional bombs can devastate a city by blast, fire. Nuclear weapons are considered weapons of destruction, and their use. Nuclear weapons have been used twice in nuclear warfare, both times by the United States against Japan near the end of World War II, the bombings resulted in the deaths of approximately 200,000 civilians and military personnel from acute injuries sustained from the explosions. The ethics of the bombings and their role in Japans surrender remain the subject of scholarly, since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have been detonated on over two thousand occasions for the purposes of testing and demonstration. Only a few nations possess such weapons or are suspected of seeking them, israel is also believed to possess nuclear weapons, though in a policy of deliberate ambiguity, it does not acknowledge having them. Germany, Italy, Turkey, Belgium and the Netherlands are nuclear weapons sharing states, south Africa is the only country to have independently developed and then renounced and dismantled its nuclear weapons. Modernisation of weapons continues to occur, all existing nuclear weapons derive some of their explosive energy from nuclear fission reactions. Weapons whose explosive output is exclusively from fission reactions are commonly referred to as bombs or atom bombs. This has long noted as something of a misnomer, as their energy comes from the nucleus of the atom. The latter approach is considered more sophisticated than the former and only the approach can be used if the fissile material is plutonium. A major challenge in all nuclear weapon designs is to ensure that a significant fraction of the fuel is consumed before the weapon destroys itself. The amount of energy released by fission bombs can range from the equivalent of just under a ton to upwards of 500,000 tons of TNT, all fission reactions necessarily generate fission products, the radioactive remains of the atomic nuclei split by the fission reactions. Many fission products are highly radioactive or moderately radioactive. Fission products are the radioactive component of nuclear fallout
4.
Nuclear fuel
–
Nuclear fuel is a substance that is used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission, most nuclear fuels contain heavy fissile elements that are capable of nuclear fission, such as uranium-235 or plutonium-239. When the unstable nuclei of atoms are hit by a slow-moving neutron, they split. These neutrons then go on to split more nuclei and this creates a self-sustaining chain reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon. The processes involved in mining, refining, purifying, using, Nuclear fuel has the highest energy density of all practical fuel sources. Uranium dioxide is a black semiconducting solid and it can be made by reacting uranyl nitrate with a base to form a solid. It is heated to form U3O8 that can then be converted by heating in an argon / hydrogen mixture to form UO2, the UO2 is then mixed with an organic binder and pressed into pellets, these pellets are then fired at a much higher temperature to sinter the solid. The aim is to form a solid which has few pores. The thermal conductivity of uranium dioxide is low compared with that of zirconium metal. It is important to note that the corrosion of uranium dioxide in an environment is controlled by similar electrochemical processes to the galvanic corrosion of a metal surface. Mixed oxide, or MOX fuel, is a blend of plutonium, MOX fuel is an alternative to low enriched uranium fuel used in the light water reactors which predominate nuclear power generation. Some concern has been expressed that used MOX cores will introduce new disposal challenges, reprocessing of commercial nuclear fuel to make MOX was done in the Sellafield MOX Plant. As of 2015, MOX fuel is made in France, and to an extent in Russia, India. China plans to develop fast breeder reactors and reprocessing, reprocessing of spent commercial-reactor nuclear fuel has not been permitted in the United States due to nonproliferation considerations. It behaves like U-235 and its fission releases a similar amount of energy, the higher the burn-up, the more plutonium in the spent fuel, but the lower the fraction of fissile plutonium. Typically about one percent of the used fuel discharged from a reactor is plutonium, worldwide, some 70 tonnes of plutonium contained in used fuel is removed when refueling reactors each year. Metal fuels have the advantage of a higher heat conductivity than oxide fuels. Metal fuels have a history of use, stretching from the Clementine reactor in 1946 to many test
5.
Nuclear reactor
–
This article is a subarticle of Nuclear power. A nuclear reactor, formerly known as a pile, is a device used to initiate. Nuclear reactors are used at power plants for electricity generation. Heat from nuclear fission is passed to a fluid, which runs through steam turbines. These either drive a ships propellers or turn electrical generators, Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for medical and industrial use, some are run only for research. As of April 2014, the IAEA reports there are 435 nuclear power reactors in operation, when a large fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it may undergo nuclear fission. The heavy nucleus splits into two or more nuclei, releasing kinetic energy, gamma radiation, and free neutrons. A portion of neutrons may later be absorbed by other fissile atoms and trigger further fission events, which release more neutrons. This is known as a chain reaction. To control such a chain reaction, neutron poisons and neutron moderators can change the portion of neutrons that will go on to cause more fission. Nuclear reactors generally have automatic and manual systems to shut the fission reaction down if monitoring detects unsafe conditions, commonly-used moderators include regular water, solid graphite and heavy water. Some experimental types of reactor have used beryllium, and hydrocarbons have been suggested as another possibility, the reactor core generates heat in a number of ways, The kinetic energy of fission products is converted to thermal energy when these nuclei collide with nearby atoms. The reactor absorbs some of the rays produced during fission. Heat is produced by the decay of fission products and materials that have been activated by neutron absorption. This decay heat-source will remain for some even after the reactor is shut down. A kilogram of uranium-235 converted via nuclear processes releases approximately three times more energy than a kilogram of coal burned conventionally. A nuclear reactor coolant — usually water but sometimes a gas or a metal or molten salt — is circulated past the reactor core to absorb the heat that it generates
6.
United Nations
–
The United Nations is an intergovernmental organization to promote international co-operation. A replacement for the ineffective League of Nations, the organization was established on 24 October 1945 after World War II in order to prevent another such conflict, at its founding, the UN had 51 member states, there are now 193. The headquarters of the UN is in Manhattan, New York City, further main offices are situated in Geneva, Nairobi, and Vienna. The organization is financed by assessed and voluntary contributions from its member states, the UNs mission to preserve world peace was complicated in its early decades by the Cold War between the US and Soviet Union and their respective allies. The organization participated in actions in Korea and the Congo. After the end of the Cold War, the UN took on major military, the UN has six principal organs, the General Assembly, the Security Council, the Economic and Social Council, the Secretariat, the International Court of Justice, and the UN Trusteeship Council. UN System agencies include the World Bank Group, the World Health Organization, the World Food Programme, UNESCO, the UNs most prominent officer is the Secretary-General, an office held by Portuguese António Guterres since 2017. Non-governmental organizations may be granted consultative status with ECOSOC and other agencies to participate in the UNs work, the organization won the Nobel Peace Prize in 2001, and a number of its officers and agencies have also been awarded the prize. Other evaluations of the UNs effectiveness have been mixed, some commentators believe the organization to be an important force for peace and human development, while others have called the organization ineffective, corrupt, or biased. Following the catastrophic loss of life in the First World War, the earliest concrete plan for a new world organization began under the aegis of the US State Department in 1939. It incorporated Soviet suggestions, but left no role for France, four Policemen was coined to refer to four major Allied countries, United States, United Kingdom, Soviet Union, and China, which emerged in the Declaration by United Nations. Roosevelt first coined the term United Nations to describe the Allied countries, the term United Nations was first officially used when 26 governments signed this Declaration. One major change from the Atlantic Charter was the addition of a provision for religious freedom, by 1 March 1945,21 additional states had signed. Each Government pledges itself to cooperate with the Governments signatory hereto, the foregoing declaration may be adhered to by other nations which are, or which may be, rendering material assistance and contributions in the struggle for victory over Hitlerism. During the war, the United Nations became the term for the Allies. To join, countries had to sign the Declaration and declare war on the Axis, at the later meetings, Lord Halifax deputized for Mr. Eden, Wellington Koo for T. V. Soong, and Mr Gromyko for Mr. Molotov. The first meetings of the General Assembly, with 51 nations represented, the General Assembly selected New York City as the site for the headquarters of the UN, and the facility was completed in 1952. Its site—like UN headquarters buildings in Geneva, Vienna, and Nairobi—is designated as international territory, the Norwegian Foreign Minister, Trygve Lie, was elected as the first UN Secretary-General
7.
Glenn T. Seaborg
–
Glenn Theodore Seaborg was an American chemist whose involvement in the synthesis, discovery and investigation of ten transuranium elements earned him a share of the 1951 Nobel Prize in Chemistry. His work in this also led to his development of the actinide concept. He advised ten US Presidents – from Harry S, throughout his career, Seaborg worked for arms control. He was a signatory to the Franck Report and contributed to the Limited Test Ban Treaty, the Nuclear Non-Proliferation Treaty and he was a well-known advocate of science education and federal funding for pure research. After sharing the 1951 Nobel Prize in Chemistry with Edwin McMillan, he received approximately 50 honorary doctorates and numerous other awards, the list of things named after Seaborg ranges from his atomic element to an asteroid. He was an author, penning numerous books and 500 journal articles. He was once listed in the Guinness Book of World Records as the person with the longest entry in Whos Who in America, Glenn Theodore Seaborg was born in Ishpeming, Michigan, on April 19,1912, the son of Herman Theodore and Selma Olivia Erickson Seaborg. He had one sister, Jeanette, who was two years younger and his family spoke Swedish at home. When Glenn Seaborg was a boy, the moved to Los Angeles County, California, settling in a subdivision called Home Gardens, later annexed to the City of South Gate. About this time he changed the spelling of his first name from Glen to Glenn, Seaborg kept a daily journal from 1927 until he suffered a stroke in 1998. As a youth, Seaborg was both a sports fan and an avid movie buff. His mother encouraged him to become a bookkeeper as she felt his interests were impractical. He did not take an interest in science until his year when he was inspired by Dwight Logan Reid. Seaborg graduated from Jordan in 1929 at the top of his class and received a bachelor of degree in chemistry at the University of California, Los Angeles. He worked his way through school as a stevedore and an assistant at Firestone. Seaborg was a member of the chemistry fraternity Alpha Chi Sigma. As a graduate student in the 1930s Seaborg performed wet chemistry research for his advisor Gilbert Newton Lewis, and published three papers with him on the theory of acids and bases. Seaborg studied the text Applied Radiochemistry by Otto Hahn, of the Kaiser Wilhelm Institute for Chemistry in Berlin, for several years, Seaborg conducted important research in artificial radioactivity using the Lawrence cyclotron at UC Berkeley
8.
Cold War
–
The Cold War was a state of geopolitical tension after World War II between powers in the Eastern Bloc and powers in the Western Bloc. Historians do not fully agree on the dates, but a common timeframe is the period between 1947, the year the Truman Doctrine was announced, and 1991, the year the Soviet Union collapsed. The term cold is used there was no large-scale fighting directly between the two sides, although there were major regional wars, known as proxy wars, supported by the two sides. The Cold War split the temporary alliance against Nazi Germany, leaving the Soviet Union. The USSR was a Marxist–Leninist state ruled by its Communist Party and secret police, the Party controlled the press, the military, the economy and all organizations. In opposition stood the West, dominantly democratic and capitalist with a free press, a small neutral bloc arose with the Non-Aligned Movement, it sought good relations with both sides. The two superpowers never engaged directly in full-scale armed combat, but they were armed in preparation for a possible all-out nuclear world war. The first phase of the Cold War began in the first two years after the end of the Second World War in 1945, the Berlin Blockade was the first major crisis of the Cold War. With the victory of the communist side in the Chinese Civil War and the outbreak of the Korean War, the USSR and USA competed for influence in Latin America, and the decolonizing states of Africa and Asia. Meanwhile, the Hungarian Revolution of 1956 was stopped by the Soviets, the expansion and escalation sparked more crises, such as the Suez Crisis, the Berlin Crisis of 1961, and the Cuban Missile Crisis of 1962. The USSR crushed the 1968 Prague Spring liberalization program in Czechoslovakia, détente collapsed at the end of the decade with the beginning of the Soviet–Afghan War in 1979. The early 1980s were another period of elevated tension, with the Soviet downing of Korean Air Lines Flight 007, the United States increased diplomatic, military, and economic pressures on the Soviet Union, at a time when the communist state was already suffering from economic stagnation. In the mid-1980s, the new Soviet leader Mikhail Gorbachev introduced the reforms of perestroika and glasnost. Pressures for national independence grew stronger in Eastern Europe, especially Poland, Gorbachev meanwhile refused to use Soviet troops to bolster the faltering Warsaw Pact regimes as had occurred in the past. The result in 1989 was a wave of revolutions that peacefully overthrew all of the communist regimes of Central, the Communist Party of the Soviet Union itself lost control and was banned following an abortive coup attempt in August 1991. This in turn led to the dissolution of the USSR in December 1991. The United States remained as the only superpower. The Cold War and its events have left a significant legacy and it is often referred to in popular culture, especially in media featuring themes of espionage and the threat of nuclear warfare
9.
Hanford Site
–
The Hanford Site is a mostly decommissioned nuclear production complex operated by the United States federal government on the Columbia River in the U. S. state of Washington. The site has been known by names, including, Hanford Project, Hanford Works, Hanford Engineer Works. Established in 1943 as part of the Manhattan Project in Hanford, south-central Washington, the site was home to the B Reactor, the first full-scale plutonium production reactor in the world. Plutonium manufactured at the site was used in the first nuclear bomb, tested at the Trinity site, and in Fat Man, Nuclear technology developed rapidly during this period, and Hanford scientists produced major technological achievements. DOE later found water intruding into at least 14 single-shell tanks, in 2012, DOE discovered a leak also from a double-shell tank caused by construction flaws and corrosion in the bottom, and that 12 double-shell tanks have similar construction flaws. Since then, DOE changed to monitoring single-shell tanks monthly and double-shell tanks every 3 years, in March 2014, DOE announced further delays in the construction of the Waste Treatment Plant, which will affect the schedule for removing waste from the tanks. Intermittent discoveries of undocumented contamination have slowed the pace and raised the cost of cleanup, in 2007, the Hanford site represented two-thirds of the nations high-level radioactive waste by volume. Hanford is currently the most contaminated site in the United States and is the focus of the nations largest environmental cleanup. On November 10,2015, it was designated as part of the Manhattan Project National Historical Park alongside other sites in Oak Ridge, the Hanford Site occupies 586 square miles —roughly equivalent to half of the total area of Rhode Island—within Benton County, Washington. This land is closed to the general public and it is a desert environment receiving under 10 inches of annual precipitation, covered mostly by shrub-steppe vegetation. The Columbia River flows along the site for approximately 50 miles, the original site was 670 square miles and included buffer areas across the river in Grant and Franklin counties. Some of this land has returned to private use and is now covered with orchards. In 2000, large portions of the site were turned over to the Hanford Reach National Monument, the site is divided by function into three main areas. The site is bordered on the southeast by the Tri-Cities, an area composed of Richland, Kennewick, Pasco, and smaller communities. Hanford is an economic base for these cities. The confluence of the Yakima, Snake, and Columbia rivers has been a place for native peoples for centuries. The archaeological record of Native American habitation of this area back over ten thousand years. Tribes and nations including the Yakama, Nez Perce, and Umatilla used the area for hunting, fishing, Native American use of the area continued into the 20th century, even as the tribes were relocated to reservations
10.
Nuclear fuel cycle
–
The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. If spent fuel is not reprocessed, the cycle is referred to as an open fuel cycle, if the spent fuel is reprocessed. Nuclear power relies on fissionable material that can sustain a reaction with neutrons. Examples of such materials include uranium and plutonium, most nuclear reactors use a moderator to lower the kinetic energy of the neutrons and increase the probability that fission will occur. This allows reactors to use material with far lower concentration of fissile isotopes than nuclear weapons, graphite and heavy water are the most effective moderators, because they slow the neutrons through collisions without absorbing them. Reactors using heavy water or graphite as the moderator can operate using natural uranium, another type of MOX fuel involves mixing LEU with thorium, which generates the fissile isotope U-233. Some reactors do not use moderators to slow the neutrons, like nuclear weapons, which also use unmoderated or fast neutrons, these fast-neutron reactors require much higher concentrations of fissile isotopes in order to sustain a chain reaction. They are also capable of breeding fissile isotopes from fertile materials, during the nuclear reaction inside a reactor, the fissile isotopes in nuclear fuel are consumed, producing more and more fission products, most of which are considered radioactive waste. The buildup of fission products and consumption of fissile isotopes eventually stop the nuclear reaction, when 3% enriched LEU fuel is used, the spent fuel typically consists of roughly 1% U-235, 95% U-238, 1% plutonium and 3% fission products. Safe management of these byproducts of nuclear power, including their storage, uranium reserves are the amounts of ore that are estimated to be recoverable at stated costs. Uranium in nature consists primarily of two isotopes, U-238 and U-235, the numbers refer to the atomic mass number for each isotope, or the number of protons and neutrons in the atomic nucleus. Naturally occurring uranium consists of approximately 99. 28% U-238 and 0. 71% U-235, the atomic nucleus of U-235 will nearly always fission when struck by a free neutron, and the isotope is therefore said to be a fissile isotope. The nucleus of a U-238 atom on the hand, rather than undergoing fission when struck by a free neutron, will nearly always absorb the neutron. This isotope then undergoes natural radioactive decay to yield Pu-239, which, the atoms of U-238 are said to be fertile, because, through neutron irradiation in the core, some eventually yield atoms of fissile Pu-239. Uranium ore can be extracted through mining in open pit. In-situ leach mining methods also are used to mine uranium in the United States, in this technology, uranium is leached from the in-place ore through an array of regularly spaced wells and is then recovered from the leach solution at a surface plant. Uranium ores in the United States typically range from about 0.05 to 0. 3% uranium oxide, some uranium deposits developed in other countries are of higher grade and are also larger than deposits mined in the United States. Uranium is also present in very low-grade amounts in some domestic phosphate-bearing deposits of marine origin, mined uranium ores normally are processed by grinding the ore materials to a uniform particle size and then treating the ore to extract the uranium by chemical leaching
11.
Table of nuclides
–
A table of nuclides or chart of nuclides is a two-dimensional graph in which one axis represents the number of neutrons and the other represents the number of protons in an atomic nucleus. Each point plotted on the graph represents the nuclide of a real or hypothetical chemical element. This system of ordering nuclides can offer an insight into the characteristics of isotopes than the better-known periodic table. A chart or table of nuclides is a map to the nuclear, or radioactive, behaviour of nuclides. It contrasts with a table, which only maps their chemical behavior. Nuclide charts organize isotopes along the X axis by their numbers of neutrons and along the Y axis by their numbers of protons and this representation was first published by Giorgio Fea in 1935, and expanded by Emilio Segrè in 1945 or G. Seaborg. In 1958, Walter Seelmann-Eggebert and Gerda Pfennig published the first edition of the Karlsruhe Nuclide Chart and its 7th edition was made available in 2006. It has become a tool of the nuclear community. The isotope table below shows isotopes of the elements, including all with half-life of at least one day. They are arranged with increasing numbers from left to right. Cell colour denotes the half-life of each isotope, if a border is present, in graphical browsers, each isotope also has a tool tip indicating its half-life. Each color represents certain range of length of half-life, and the color of border indicates the half-life of its nuclear isomer state, some nuclides have multiple nuclear isomers, and this table notes the longest one. Dotted borders mean it has a nuclear isomer, and its color is same as the normal counterpart, isotopes are nuclides with the same number of protons but differing numbers of neutrons, that is, they have the same atomic number and are therefore the same chemical element. Isotopes neighbor each other vertically, e. g. carbon-12, carbon-13, carbon-14 or oxygen-15, oxygen-16, isotones are nuclides with the same number of neutrons but differing number of protons. Example, carbon-14, nitrogen-15, oxygen-16 in the table above. Isobars are nuclides with the number of nucleons, i. e. mass number. Isobars neighbor each other diagonally from lower-left to upper-right, example, carbon-14, nitrogen-14, oxygen-14 in the sample table above. Isodiaphers are nuclides with the difference between neutrons and protons
12.
Molten-Salt Reactor Experiment
–
The MSRE was a 7.4 MWth test reactor simulating the neutronic kernel of a type of inherently safer epithermal thorium breeder reactor called the liquid fluoride thorium reactor. It primarily used two fuels, first uranium-235 and later uranium-233, the latter 233UF4 was the result of breeding from thorium in other reactors. Since this was an engineering test, the large, expensive breeding blanket of thorium salt was omitted in favor of neutron measurements, in the MSRE, the heat from the reactor core was shed via a cooling system using air blown over radiators. It is thought similar reactors could power high-efficiency heat engines such as gas turbines. The MSREs piping, core vat and structural components were made from Hastelloy-N, the result promised to be a simple, reliable reactor. For simplicity, it was to be a small, one-fluid reactor operating at 10 MWth or less. The pyrolytic graphite core, grade CGB, also served as the moderator, before the MSRE development began, tests had shown that salt would not permeate graphite in which the pores were on the order of a micrometer. The first fuel was 33% 235U, later a smaller amount of 233UF4 was used, by 1960 a better understanding of fluoride salt based molten-salt reactors had emerged due to earlier molten salt reactor research for the Aircraft Reactor Experiment. Fluoride salts are ionic, and when melted, are stable at high temperatures, low pressures. Low pressure stability permits less robust reactor vessels and increases reliability, the high reactivity of fluorine traps most fission reaction byproducts. It appeared that the salt would permit on-site chemical separation of the fuel. The fuel system was located in sealed cells, laid out for maintenance with long-handled tools through openings in the top shielding, a tank of LiF-BeF2 salt was used to flush the fuel circulating system before and after maintenance. In a cell adjacent to the reactor was a facility for bubbling gas through the fuel or flush salt, H2-hydrogen fluoride to remove oxide. Haubenreich and Engel, Robertson, and Lindauer provide more detailed descriptions of the reactor and processing plant. The bowl of the pump was the surge space for the circulating loop. Removing the most significant neutron poison xenon-135 made the reactor safer and easier to restart, in solid-fuel reactors, on restart the 135Xe in the fuel absorbs neutrons, followed by a sudden jump in reactivity as the 135Xe is burned out. Conventional reactors may have to wait hours until xenon-135 decays after shutting down, also in the pump bowl was a port through which salt samples could be taken or capsules of concentrated fuel-enriching salt could be introduced. At the time, the temperatures were seen almost as a disadvantage
.jpg)