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136-400: Reactors using heavy water as their moderator have a number of advantages due to their improved neutron economy . This allows them to run on fuels that do not work in conventional light water reactors . CVTR, for instance, used slight enrichment , between 1.5 and 2%, compared to 3 to 5% for conventional designs. This means fuel costs are lower, the tradeoff being higher capital costs due to

272-414: A coal fired power plant in overall design, in that a boiler is used to produce steam which then drives a steam turbine to produce electricity. The boiler is the only significant difference. In a coal plant, this normally consists of a system to burn the coal while water circulates through the boiler in a series of tubes. The water is held under pressure in order to increase its boiling point , which makes

408-739: A natural uranium reactor, and in August 1940, along with Georgy Flyorov , submitted a plan to the Russian Academy of Sciences calculating that 15 tons of heavy water were needed for a reactor. With the Soviet Union having no uranium mines at the time, young Academy workers were sent to Leningrad photographic shops to buy uranium nitrate, but the entire heavy water project was halted in 1941 when German forces invaded during Operation Barbarossa . By 1943, Soviet scientists had discovered that all scientific literature relating to heavy water had disappeared from

544-402: A black semiconducting solid. It can be made by heating uranyl nitrate to form UO 2 . This is then converted by heating with hydrogen to form UO 2 . It can be made from enriched uranium hexafluoride by reacting with ammonia to form a solid called ammonium diuranate , (NH 4 ) 2 U 2 O 7 . This is then heated ( calcined ) to form UO 3 and U 3 O 8 which

680-533: A degree of 25% deuteration causes (sometimes irreversible) sterility, because neither gametes nor zygotes can develop. High concentrations of heavy water (90%) rapidly kill fish, tadpoles , flatworms , and Drosophila . Mice raised from birth with 30% heavy water have 25% deuteration in body fluid and 10% in brains. They are normal except for sterility. Deuteration during pregnancy induces fetal abnormality. Higher deuteration in body fluid causes death. Mammals (for example, rats) given heavy water to drink die after

816-596: A disgruntled employee at the Point Lepreau Nuclear Generating Station in Canada obtained a sample (estimated as about a "half cup") of heavy water from the primary heat transport loop of the nuclear reactor , and loaded it into a cafeteria drink dispenser. Eight employees drank some of the contaminated water. The incident was discovered when employees began leaving bioassay urine samples with elevated tritium levels. The quantity of heavy water involved

952-432: A failure of bone marrow (producing bleeding and infections) and of intestinal-barrier functions (producing diarrhea and loss of fluids ). Despite the problems of plants and animals in living with too much deuterium, prokaryotic organisms such as bacteria, which do not have the mitotic problems induced by deuterium, may be grown and propagated in fully deuterated conditions, resulting in replacement of all hydrogen atoms in

1088-432: A fuel would be so expensive it is likely that the fuel would require pyroprocessing to enable recovery of the N. It is likely that if the fuel was processed and dissolved in nitric acid that the nitrogen enriched with N would be diluted with the common N. Fluoride volatility is a method of reprocessing that does not rely on nitric acid, but it has only been demonstrated in relatively small scale installations whereas

1224-539: A heavy hydrogen environment. Heavy water can be toxic to humans, but a large amount would be needed for poisoning to occur. The most cost-effective process for producing heavy water is the Girdler sulfide process . Heavy water is used in various industries and is sold in different grades of purity. Some of its applications include nuclear magnetic resonance , infrared spectroscopy , neutron moderation , neutrino detection , metabolic rate testing, neutron capture therapy , and

1360-511: A higher neutron cross section than U . As the Pu accumulates the chain reaction shifts from pure U at initiation of the fuel use to a ratio of about 70% U and 30% Pu at the end of the 18 to 24 month fuel exposure period. Mixed oxide , or MOX fuel , is a blend of plutonium and natural or depleted uranium which behaves similarly (though not identically) to the enriched uranium feed for which most nuclear reactors were designed. MOX fuel

1496-417: A highly deuterated environment, some normal reactions in cells are disrupted. Particularly hard-hit by heavy water are the delicate assemblies of mitotic spindle formations necessary for cell division in eukaryotes . Plants stop growing and seeds do not germinate when given only heavy water, because heavy water stops eukaryotic cell division. Tobacco does not germinate, but wheat does. The deuterium cell

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1632-453: A kernel of UO X fuel (sometimes UC or UCO), which has been coated with four layers of three isotropic materials deposited through fluidized chemical vapor deposition (FCVD). The four layers are a porous buffer layer made of carbon that absorbs fission product recoils, followed by a dense inner layer of protective pyrolytic carbon (PyC), followed by a ceramic layer of SiC to retain fission products at elevated temperatures and to give

1768-449: A more recent study confirmed anecdotal observation that heavy water tastes slightly sweet to humans, with the effect mediated by the TAS1R2 / TAS1R3 taste receptor. Rats given a choice between distilled normal water and heavy water were able to avoid the heavy water based on smell, and it may have a different taste. Some people report that minerals in water affect taste, e.g. potassium lending

1904-613: A properly designed reactor. Two such reactor designs are the prismatic-block gas-cooled reactor (such as the GT-MHR ) and the pebble-bed reactor (PBR). Both of these reactor designs are high temperature gas reactors (HTGRs). These are also the basic reactor designs of very-high-temperature reactors (VHTRs), one of the six classes of reactor designs in the Generation IV initiative that is attempting to reach even higher HTGR outlet temperatures. TRISO fuel particles were originally developed in

2040-859: A similar design to the CANDU but built by German KWU was originally designed for non-enriched fuel but since switched to slightly enriched fuel with a U content about 0.1 percentage points higher than in natural uranium. Various other nuclear fuel forms find use in specific applications, but lack the widespread use of those found in BWRs, PWRs, and CANDU power plants. Many of these fuel forms are only found in research reactors, or have military applications. Magnox (magnesium non-oxidising) reactors are pressurised, carbon dioxide –cooled, graphite - moderated reactors using natural uranium (i.e. unenriched) as fuel and Magnox alloy as fuel cladding. Working pressure varies from 6.9 to 19.35 bars (100.1 to 280.6 psi) for

2176-448: A smaller effect on the physical properties. Tritiated water contains tritium ( H) in place of protium ( H) or deuterium ( H). Since tritium is radioactive, tritiated water is also radioactive. The physical properties of water and heavy water differ in several respects. Heavy water is less dissociated than light water at given temperature, and the true concentration of D ions is less than   H ions would be for light water at

2312-419: A solid, semi-heavy water in the form of ice could be stable. This is due to collisions between water vapor molecules being almost completely negligible in the gas phase at standard temperatures, and once crystallized, collisions between the molecules cease altogether due to the rigid lattice structure of solid ice. The US scientist and Nobel laureate Harold Urey discovered the isotope deuterium in 1931 and

2448-460: A standard mouse model of human melanoma , an effect attributed to selective induction of cellular stress signaling and gene expression in tumor cells. Because it would take a very large amount of heavy water to replace 25% to 50% of a human being's body water (water being in turn 50–75% of body weight ) with heavy water, accidental or intentional poisoning with heavy water is unlikely to the point of practical disregard. Poisoning would require that

2584-473: A sweet taste to hard water, but there are many factors of a perceived taste in water besides mineral contents. Heavy water lacks the characteristic blue color of light water; this is because the molecular vibration harmonics, which in light water cause weak absorption in the red part of the visible spectrum, are shifted into the infrared and thus heavy water does not absorb red light. No physical properties are listed for "pure" semi-heavy water because it

2720-551: A thermal output of about 65 MW th and a gross electrical output of 19 MW. Westinghouse Atomic Power Division was responsible for the design of the nuclear systems while Stone and Webster Engineering designed the remainder of the plant. The reactor consisted of 36 vertical U-tube fuel channels in a moderator tank which was 10 feet in diameter and 16 feet tall. Each leg of the U-tube contained one fuel assembly made up of 19 fuel rods . The reactor used enriched uranium ; 12 of

2856-446: A true acidic pD can be estimated from the directly pH meter measured pHa, such that pD+ = pHa (apparent reading from pH meter) + 0.41. The electrode correction for alkaline conditions is 0.456 for heavy water. The alkaline correction is then pD+ = pH a (apparent reading from pH meter) + 0.456. These corrections are slightly different from the differences in p[D+] and p[OD-] of 0.44 from the corresponding ones in heavy water. Heavy water

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2992-476: A typical core loading is on the order of 4500–6500 bundles, depending on the design. Modern types typically have 37 identical fuel pins radially arranged about the long axis of the bundle, but in the past several different configurations and numbers of pins have been used. The CANFLEX bundle has 43 fuel elements, with two element sizes. It is also about 10 cm (4 inches) in diameter, 0.5 m (20 in) long and weighs about 20 kg (44 lb) and replaces

3128-399: A typical spent fuel assembly still exceeds 10,000 rem/hour, resulting in a fatal dose in just minutes. Two main modes of release exist, the fission products can be vaporised or small particles of the fuel can be dispersed. Post-Irradiation Examination (PIE) is the study of used nuclear materials such as nuclear fuel. It has several purposes. It is known that by examination of used fuel that

3264-404: A way as to ensure low contamination with non-radioactive carbon (not a common fission product and absent in nuclear reactors that don't use it as a moderator ) then fluoride volatility could be used to separate the C produced by producing carbon tetrafluoride . C is proposed for use in particularly long lived low power nuclear batteries called diamond batteries . Much of what

3400-498: A week, at a time when their body water approaches about 50% deuteration. The mode of death appears to be the same as that in cytotoxic poisoning (such as chemotherapy ) or in acute radiation syndrome (though deuterium is not radioactive), and is caused by deuterium's action in generally inhibiting cell division. It is more toxic to malignant cells than normal cells, but the concentrations needed are too high for regular use. As may occur in chemotherapy, deuterium-poisoned mammals die of

3536-461: Is 10.6% denser than ordinary water, and heavy water's physically different properties can be seen without equipment if a frozen sample is dropped into normal water, as it will sink. If the water is ice-cold the higher melting temperature of heavy ice can also be observed: it melts at 3.7 °C, and thus does not melt in ice-cold normal water. A 1935 experiment reported not the "slightest difference" in taste between ordinary and heavy water. However,

3672-523: Is a consequence of the ratio of nuclear masses between the isotopes of hydrogen, which is much greater than for any other element. Deuterium oxide is used to enhance boron neutron capture therapy , but this effect does not rely on the biological or chemical effects of deuterium, but instead on deuterium's ability to moderate (slow) neutrons without capturing them. 2021 experimental evidence indicates that systemic administration of deuterium oxide (30% drinking water supplementation) suppresses tumor growth in

3808-475: Is able to release xenon gas, which normally acts as a neutron absorber ( Xe is the strongest known neutron poison and is produced both directly and as a decay product of I as a fission product ) and causes structural occlusions in solid fuel elements (leading to the early replacement of solid fuel rods with over 98% of the nuclear fuel unburned, including many long-lived actinides). In contrast, molten-salt reactors are capable of retaining

3944-436: Is actually about 50% HDO and 25% each of H 2 O and D 2 O , in dynamic equilibrium . In normal water, about 1 molecule in 3,200 is HDO (one hydrogen in 6,400 is H ), and heavy water molecules ( D 2 O ) only occur in a proportion of about 1 molecule in 41 million (i.e. one in 6,400 ) . Thus semiheavy water molecules are far more common than "pure" (homoisotopic) heavy water molecules. Water enriched in

4080-487: Is an alternative to low enriched uranium (LEU) 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, though MOX is a means to dispose of surplus plutonium by transmutation . Reprocessing of commercial nuclear fuel to make MOX was done in the Sellafield MOX Plant (England). As of 2015, MOX fuel

4216-489: Is commonly composed of enriched uranium sandwiched between metal cladding. Plate-type fuel is used in several research reactors where a high neutron flux is desired, for uses such as material irradiation studies or isotope production, without the high temperatures seen in ceramic, cylindrical fuel. It is currently used in the Advanced Test Reactor (ATR) at Idaho National Laboratory , and the nuclear research reactor at

Carolinas–Virginia Tube Reactor - Misplaced Pages Continue

4352-410: Is compacted to cylindrical pellets and sintered at high temperatures to produce ceramic nuclear fuel pellets with a high density and well defined physical properties and chemical composition. A grinding process is used to achieve a uniform cylindrical geometry with narrow tolerances. Such fuel pellets are then stacked and filled into the metallic tubes. The metal used for the tubes depends on the design of

4488-558: Is described below. Emilian Bratu and Otto Redlich studied the autodissociation of heavy water in 1934. In the 1930s, it was suspected by the United States and Soviet Union that Austrian chemist Fritz Johann Hansgirg built a pilot plant for the Empire of Japan in Japanese ruled northern Korea to produce heavy water by using a new process he had invented. During the second World War,

4624-590: Is done is the ITU which is the EU centre for the study of highly radioactive materials. Materials in a high-radiation environment (such as a reactor) can undergo unique behaviors such as swelling and non-thermal creep. If there are nuclear reactions within the material (such as what happens in the fuel), the stoichiometry will also change slowly over time. These behaviors can lead to new material properties, cracking, and fission gas release. The thermal conductivity of uranium dioxide

4760-448: Is expensive and a limited resource. This led to the pressurized tube reactor concept, where the pressurized section of the system contains only enough coolant to cool the reactor, the rest of the moderator is placed around it in an unpressurized vessel. In the case of a loss-of-coolant event, only the water in the pressurized system would be lost. Design of the CVTR began around 1955. CVTR had

4896-566: Is formed into pellets and inserted into Zircaloy tubes that are bundled together. The Zircaloy tubes are about 1 centimetre (0.4 in) in diameter, and the fuel cladding gap is filled with helium gas to improve heat conduction from the fuel to the cladding. There are about 179–264 fuel rods per fuel bundle and about 121 to 193 fuel bundles are loaded into a reactor core. Generally, the fuel bundles consist of fuel rods bundled 14×14 to 17×17. PWR fuel bundles are about 4 m (13 ft) long. In PWR fuel bundles, control rods are inserted through

5032-633: Is harmless. When a large fraction of water (> 50%) in higher organisms is replaced by heavy water, the result is cell dysfunction and death. Heavy water was first produced in 1932, a few months after the discovery of deuterium. With the discovery of nuclear fission in late 1938, and the need for a neutron moderator that captured few neutrons, heavy water became a component of early nuclear energy research. Since then, heavy water has been an essential component in some types of reactors, both those that generate power and those designed to produce isotopes for nuclear weapons. These heavy water reactors have

5168-450: Is known about uranium carbide is in the form of pin-type fuel elements for liquid metal fast reactors during their intense study in the 1960s and 1970s. Recently there has been a revived interest in uranium carbide in the form of plate fuel and most notably, micro fuel particles (such as tristructural-isotropic particles). The high thermal conductivity and high melting point makes uranium carbide an attractive fuel. In addition, because of

5304-412: Is larger and is a modification of the direction of division. The cell membrane also changes, and it reacts first to the impact of heavy water. In 1972, it was demonstrated that an increase in the percentage of deuterium in water reduces plant growth. Research conducted on the growth of prokaryote microorganisms in artificial conditions of a heavy hydrogen environment showed that in this environment, all

5440-413: Is low; it is affected by porosity and burn-up. The burn-up results in fission products being dissolved in the lattice (such as lanthanides ), the precipitation of fission products such as palladium , the formation of fission gas bubbles due to fission products such as xenon and krypton and radiation damage of the lattice. The low thermal conductivity can lead to overheating of the center part of

5576-659: Is made in France at the Marcoule Nuclear Site , and to a lesser extent in Russia at the Mining and Chemical Combine , India and Japan. China plans to develop fast breeder reactors and reprocessing. The Global Nuclear Energy Partnership was a U.S. proposal in the George W. Bush administration to form an international partnership to see spent nuclear fuel reprocessed in a way that renders

Carolinas–Virginia Tube Reactor - Misplaced Pages Continue

5712-414: Is more expensive than D 2 O due to the more difficult separation of O and O. H 2 O is also used for production of fluorine-18 in radiopharmaceuticals and radiotracers , and positron emission tomography . Small amounts of O and O are naturally present in water, and most processes enriching heavy water also enrich heavier isotopes of oxygen as a side-effect. This is undesirable if

5848-502: Is much less than for the Girdler sulfide process, this method is currently uneconomical due to the expense of procuring the necessary hydrofluorocarbons. As noted, modern commercial heavy water is almost universally referred to, and sold as, deuterium oxide. It is most often sold in various grades of purity, from 98% enrichment to 99.75–99.98% deuterium enrichment (nuclear reactor grade) and occasionally even higher isotopic purity. Argentina

5984-419: Is not radioactive. Commercial-grade heavy water is slightly radioactive due to the presence of minute traces of natural tritium, but the same is true of ordinary water. Heavy water that has been used as a coolant in nuclear power plants contains substantially more tritium as a result of neutron bombardment of the deuterium in the heavy water ( tritium is a health risk when ingested in large quantities). In 1990,

6120-619: Is radioactive due to tritium content. Heavy water has different physical properties from regular water, such as being 10.6% denser and having a higher melting point. Heavy water is less dissociated at a given temperature, and it does not have the slightly blue color of regular water. It can taste slightly sweeter than regular water, though not to a significant degree. Heavy water affects biological systems by altering enzymes, hydrogen bonds, and cell division in eukaryotes . It can be lethal to multicellular organisms at concentrations over 50%. However, some prokaryotes like bacteria can survive in

6256-564: Is required to double the amount of deuterium in the body. A loss of blood pressure may partially explain the reported incidence of dizziness upon ingestion of heavy water. However, it is more likely that this symptom can be attributed to altered vestibular function . Heavy water, like ethanol, causes a temporary difference in the density of endolymph within the cupula, which confuses the vestibulo–ocular reflex and causes motion sickness symptoms. Although many people associate heavy water primarily with its use in nuclear reactors, pure heavy water

6392-421: Is the dual temperature exchange sulfide process (known as the Girdler sulfide process ) developed in parallel by Karl-Hermann Geib and Jerome S. Spevack in 1943. An alternative process, patented by Graham M. Keyser, uses lasers to selectively dissociate deuterated hydrofluorocarbons to form deuterium fluoride , which can then be separated by physical means. Although the energy consumption for this process

6528-418: Is then converted by heating with hydrogen or ammonia to form UO 2 . The UO 2 is mixed with an organic binder and pressed into pellets. The pellets are then fired at a much higher temperature (in hydrogen or argon) to sinter the solid. The aim is to form a dense solid which has few pores. The thermal conductivity of uranium dioxide is very low compared with that of zirconium metal, and it goes down as

6664-407: Is unknown. Like ethanol, heavy water temporarily changes the relative density of cupula relative to the endolymph in the vestibular organ, causing positional nystagmus , illusions of bodily rotations, dizziness, and nausea. However, the direction of nystagmus is in the opposite direction of ethanol, since it is denser than water, not lighter. Experiments with mice, rats, and dogs have shown that

6800-433: Is unstable as a bulk liquid. In the liquid state, a few water molecules are always in an ionized state , which means the hydrogen atoms can exchange among different oxygen atoms. Semi-heavy water could, in theory, be created via a chemical method, but it would rapidly transform into a dynamic mixture of 25% light water, 25% heavy water, and 50% semi-heavy. However, if it were made in the gas phase and directly deposited into

6936-399: Is used by nuclear power stations or other nuclear devices to generate energy. For fission reactors, the fuel (typically based on uranium ) is usually based on the metal oxide ; the oxides are used rather than the metals themselves because the oxide melting point is much higher than that of the metal and because it cannot burn, being already in the oxidized state. Uranium dioxide is

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7072-529: The C concentration will be too low for use in nuclear batteries without enrichment. Nuclear graphite discharged from reactors where it was used as a moderator presents the same issue. Liquid fuels contain dissolved nuclear fuel and have been shown to offer numerous operational advantages compared to traditional solid fuel approaches. Liquid-fuel reactors offer significant safety advantages due to their inherently stable "self-adjusting" reactor dynamics. This provides two major benefits: virtually eliminating

7208-452: The Pu is 'burned' in the reactor, providing about one third of the total energy. It behaves like U and its fission releases a similar amount of energy. The higher the burnup , the more plutonium is present in the spent fuel, but the available fissile plutonium is lower. Typically about one percent of the used fuel discharged from a reactor is plutonium, and some two thirds of this is fissile (c. 50% Pu , 15% Pu ). Metal fuels have

7344-457: The Chernobyl disaster . Most modern reactors use enriched uranium with ordinary water as the moderator. Semiheavy water , HDO, exists whenever there is water with light hydrogen (protium, H ) and deuterium (D or H ) in the mix. This is because hydrogen atoms ( H and H) are rapidly exchanged between water molecules. Water containing 50% H and 50% H in its hydrogen,

7480-611: The Dana, Indiana plant in 1945 and at the Savannah River Site in 1952. India is the world's largest producer of heavy water through its Heavy Water Board . It exports heavy water to countries including the Republic of Korea, China, and the United States. In 1934, Norsk Hydro built the first commercial heavy water plant at Vemork , Tinn , eventually producing 4 kilograms (8.8 lb) per day. From 1940 and throughout World War II ,

7616-615: The IUPAC Gold Book can also refer to water in which a higher than usual proportion of hydrogen atoms are deuterium. For comparison, Vienna Standard Mean Ocean Water (the "ordinary water" used for a deuterium standard) contains about 156 deuterium atoms per million hydrogen atoms; that is, 0.0156% of the hydrogen atoms are H. Thus heavy water as defined by the Gold Book includes semiheavy water (hydrogen-deuterium oxide, HDO) and other mixtures of D 2 O , H 2 O , and HDO in which

7752-752: The NKVD deported to the Soviet Union from Germany the German scientists who had worked on heavy water production during the war, including Karl-Hermann Geib , the inventor of the Girdler sulfide process . These German scientists worked under the supervision of German physical chemist Max Volmer at the Institute of Physical Chemistry in Moscow with the plant they constructed producing large quantities of heavy water by 1948. Different isotopes of chemical elements have slightly different chemical behaviors, but for most elements

7888-506: The Savannah River Site . The first of the five heavy water reactors came online in 1953, and the last was placed in cold shutdown in 1996. The reactors were heavy water reactors so that they could produce both plutonium and tritium for the US nuclear weapons program. The U.S. developed the Girdler sulfide chemical exchange production process—which was first demonstrated on a large scale at

8024-556: The University of Massachusetts Lowell Radiation Laboratory . Sodium-bonded fuel consists of fuel that has liquid sodium in the gap between the fuel slug (or pellet) and the cladding. This fuel type is often used for sodium-cooled liquid metal fast reactors. It has been used in EBR-I, EBR-II, and the FFTF. The fuel slug may be metallic or ceramic. The sodium bonding is used to reduce the temperature of

8160-412: The anhydrobiotic species of nematode Panagrolaimus superbus (nearly 100% D 2 O). A comprehensive study of heavy water on the fission yeast Schizosaccharomyces pombe showed that the cells displayed an altered glucose metabolism and slow growth at high concentrations of heavy water. In addition, the cells activated the heat-shock response pathway and the cell integrity pathway, and mutants in

8296-404: The liquid fluoride thorium reactor (LFTR), this fuel salt is also the coolant; in other designs, such as the stable salt reactor , the fuel salt is contained in fuel pins and the coolant is a separate, non-radioactive salt. There is a further category of molten salt-cooled reactors in which the fuel is not in molten salt form, but a molten salt is used for cooling. Molten salt fuels were used in

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8432-776: The monothermal ammonia-hydrogen isotopic exchange method. Since 2017, the Arroyito plant has not been operational. During the Manhattan Project the United States constructed three heavy water production plants as part of the P-9 Project at Morgantown Ordnance Works, near Morgantown, West Virginia ; at the Wabash River Ordnance Works, near Dana and Newport, Indiana ; and at the Alabama Ordnance Works, near Childersburg and Sylacauga, Alabama . Heavy water

8568-426: The steam quality before the steam entered the turbine which spun the electrical generator . After passing through the steam generator, the primary loop water was pumped back to the reactor by the primary pumps to repeat the cycle. The primary loop heavy water was pressurized to ensure that the heavy water remained liquid and did not flash to steam at any point in the loop. The U-shaped pressure tubes containing

8704-499: The 37-pin standard bundle. It has been designed specifically to increase fuel performance by utilizing two different pin diameters. Current CANDU designs do not need enriched uranium to achieve criticality (due to the lower neutron absorption in their heavy water moderator compared to light water), however, some newer concepts call for low enrichment to help reduce the size of the reactors. The Atucha nuclear power plant in Argentina,

8840-479: The CVTR, the facility was used for conducting large scale tests to provide experimental information on the response of containment structures to severe events. In the late 1960s, three tests were conducted in which large volumes of steam from the nearby coal-fired power plant was suddenly released into the CVTR Containment and the response of the plant measured. The results of these experiments were later used for

8976-401: The CVTR. Heavy water Heavy water ( deuterium oxide , H 2 O , D 2 O ) is a form of water in which hydrogen atoms are all deuterium ( H or D, also known as heavy hydrogen ) rather than the common hydrogen-1 isotope ( H , also called protium ) that makes up most of the hydrogen in normal water. The presence of the heavier isotope gives

9112-437: The Gold Book sense need not be so highly enriched. The weight of a heavy water molecule, however, is not very different from that of a normal water molecule, because about 89% of the mass of the molecule comes from the single oxygen atom rather than the two hydrogens. Heavy water is not radioactive . In its pure form, it has a density about 11% greater than water but is otherwise physically and chemically similar. Nevertheless,

9248-521: The LFTR known as the Molten Salt Reactor Experiment, as well as other liquid core reactor experiments. The liquid fuel for the molten salt reactor was a mixture of lithium, beryllium, thorium and uranium fluorides: LiF-BeF 2 -ThF 4 -UF 4 (72-16-12-0.4 mol%). It had a peak operating temperature of 705 °C in the experiment, but could have operated at much higher temperatures since

9384-475: The TRISO particle more structural integrity, followed by a dense outer layer of PyC. TRISO particles are then encapsulated into cylindrical or spherical graphite pellets. TRISO fuel particles are designed not to crack due to the stresses from processes (such as differential thermal expansion or fission gas pressure) at temperatures up to 1600 °C, and therefore can contain the fuel in the worst of accident scenarios in

9520-478: The US and an additional 35 in other countries. In a fast-neutron reactor , the minor actinides produced by neutron capture of uranium and plutonium can be used as fuel. Metal actinide fuel is typically an alloy of zirconium, uranium, plutonium, and minor actinides . It can be made inherently safe as thermal expansion of the metal alloy will increase neutron leakage. Molten plutonium, alloyed with other metals to lower its melting point and encapsulated in tantalum ,

9656-821: The United Kingdom as part of the Dragon reactor project. The inclusion of the SiC as diffusion barrier was first suggested by D. T. Livey. The first nuclear reactor to use TRISO fuels was the Dragon reactor and the first powerplant was the THTR-300 . Currently, TRISO fuel compacts are being used in some experimental reactors, such as the HTR-10 in China and the high-temperature engineering test reactor in Japan. In

9792-452: The United States, spherical fuel elements utilizing a TRISO particle with a UO 2 and UC solid solution kernel are being used in the Xe-100 , and Kairos Power is developing a 140 MWE nuclear reactor that uses TRISO. In QUADRISO particles a burnable neutron poison ( europium oxide or erbium oxide or carbide ) layer surrounds the fuel kernel of ordinary TRISO particles to better manage

9928-619: The West, which Flyorov in a letter warned Soviet leader Joseph Stalin about, and at which time there was only 2–3 kg of heavy water in the entire country. In late 1943, the Soviet purchasing commission in the U.S. obtained 1 kg of heavy water and a further 100 kg in February 1945, and upon World War II ending, the NKVD took over the project. In October 1946, as part of the Russian Alsos ,

10064-401: The absence of oxygen in this fuel (during the course of irradiation, excess gas pressure can build from the formation of O 2 or other gases) as well as the ability to complement a ceramic coating (a ceramic-ceramic interface has structural and chemical advantages), uranium carbide could be the ideal fuel candidate for certain Generation IV reactors such as the gas-cooled fast reactor . While

10200-651: The advantage of a much higher heat conductivity than oxide fuels but cannot survive equally high temperatures. Metal fuels have a long history of use, stretching from the Clementine reactor in 1946 to many test and research reactors. Metal fuels have the potential for the highest fissile atom density. Metal fuels are normally alloyed, but some metal fuels have been made with pure uranium metal. Uranium alloys that have been used include uranium aluminum, uranium zirconium , uranium silicon, uranium molybdenum, uranium zirconium hydride (UZrH), and uranium zirconium carbonitride. Any of

10336-434: The advantage of being able to run on natural uranium without using graphite moderators that pose radiological and dust explosion hazards in the decommissioning phase. The graphite moderated Soviet RBMK design tried to avoid using either enriched uranium or heavy water (being cooled with ordinary water instead) which produced the positive void coefficient that was one of a series of flaws in reactor design leading to

10472-515: The aforementioned fuels can be made with plutonium and other actinides as part of a closed nuclear fuel cycle. Metal fuels have been used in light-water reactors and liquid metal fast breeder reactors , such as Experimental Breeder Reactor II . TRIGA fuel is used in TRIGA (Training, Research, Isotopes, General Atomics ) reactors. The TRIGA reactor uses UZrH fuel, which has a prompt negative fuel temperature coefficient of reactivity , meaning that as

10608-424: The application of the new fuel-cladding material systems for various types of ATF materials. The aim of the research is to develop nuclear fuels that can tolerate loss of active cooling for a considerably longer period than the existing fuel designs and prevent or delay the release of radionuclides during an accident. This research is focused on reconsidering the design of fuel pellets and cladding, as well as

10744-590: The bacterial proteins and DNA with the deuterium isotope. This leads to a process of bootstrapping . With prokaryotes producing fully deuterated glucose, fully deuterated Escherichia coli and Torula were raised, and they could produce even more complex fully deuterated chemicals. Molds like Aspergillus could not replicate under fully deuterated conditions. In higher organisms, full replacement with heavy isotopes can be accomplished with other non-radioactive heavy isotopes (such as carbon-13, nitrogen-15, and oxygen-18), but this cannot be done for deuterium. This

10880-420: The boiling point of the molten salt was in excess of 1400 °C. The aqueous homogeneous reactors (AHRs) use a solution of uranyl sulfate or other uranium salt in water. Historically, AHRs have all been small research reactors, not large power reactors. The dual fluid reactor (DFR) has a variant DFR/m which works with eutectic liquid metal alloys, e.g. U-Cr or U-Fe. Uranium dioxide (UO 2 ) powder

11016-525: The cell integrity pathway displayed increased tolerance to heavy water. Despite its toxicity at high levels, heavy water has been observed to extend lifespan of certain yeasts by up to 85%, with the hypothesized mechanism being the reduction of reactive oxygen species turnover. Heavy water affects the period of circadian oscillations , consistently increasing the length of each cycle. The effect has been demonstrated in unicellular organisms, green plants, isopods, insects, birds, mice, and hamsters. The mechanism

11152-420: The chain-reaction. This mechanism compensates for the accumulation of undesirable neutron poisons which are an unavoidable part of the fission products, as well as normal fissile fuel "burn up" or depletion. In the generalized QUADRISO fuel concept the poison can eventually be mixed with the fuel kernel or the outer pyrocarbon. The QUADRISO concept was conceived at Argonne National Laboratory . RBMK reactor fuel

11288-516: The company Fosfatbolaget in Ljungaverk , Sweden, produced 2,300 liters per year of heavy water. The heavy water was then sold both to Germany and to the Manhattan Project for the price of 1,40 SEK per gram of heavy water. In October 1939, Soviet physicists Yakov Borisovich Zel'dovich and Yulii Borisovich Khariton concluded that heavy water and carbon were the only feasible moderators for

11424-437: The containment building was lined with an airtight layer of welded steel plates 1/2" or 1/4" thick, depending on location. From the basement floor to the interior surface of the top of the dome measured 114’-2”. The vertical walls were 2’-0” thick, the cylindrical structure had an interior diameter of 58’-0”, and the dome had a slightly larger interior radius of 29’-4”. The reactor and facilities were located at Parr, SC just to

11560-510: The coolant and contaminating it. Besides the prevention of radioactive leaks this also serves to keep the coolant as non-corrosive as feasible and to prevent reactions between chemically aggressive fission products and the coolant. For example, the highly reactive alkali metal caesium which reacts strongly with water, producing hydrogen, and which is among the more common fission products. Pressurized water reactor (PWR) fuel consists of cylindrical rods put into bundles. A uranium oxide ceramic

11696-421: The development and validation of computer model codes. The CVTR has been decommissioned and its license was withdrawn. No fuel remains on site. By fall of 2009, demolition was complete and the site was returned to greenfield status . The much larger and currently operational Virgil C. Summer Nuclear Generating Station was constructed in the 1970s, and began operating in 1984, approximately three miles north of

11832-530: The differences are far too small to have a biological effect. In the case of hydrogen, larger differences in chemical properties among protium, deuterium, and tritium occur because chemical bond energy depends on the reduced mass of the nucleus–electron system; this is altered in heavy-hydrogen compounds (hydrogen-deuterium oxide is the most common) more than for heavy-isotope substitution involving other chemical elements. The isotope effects are especially relevant in biological systems, which are very sensitive to even

11968-434: The established PUREX process is used commercially for about a third of all spent nuclear fuel (the rest being largely subject to a "once through fuel cycle"). All nitrogen-fluoride compounds are volatile or gaseous at room temperature and could be fractionally distilled from the other gaseous products (including recovered uranium hexafluoride ) to recover the initially used nitrogen. If the fuel could be processed in such

12104-491: The excess of reactivity. If the core is equipped both with TRISO and QUADRISO fuels, at beginning of life neutrons do not reach the fuel of the QUADRISO particles because they are stopped by the burnable poison. During reactor operation, neutron irradiation of the poison causes it to "burn up" or progressively transmute to non-poison isotopes, depleting this poison effect and leaving progressively more neutrons available for sustaining

12240-407: The fact that the used fuel can be cracked, it is very insoluble in water, and is able to retain the vast majority of the actinides and fission products within the uranium dioxide crystal lattice . The radiation hazard from spent nuclear fuel declines as its radioactive components decay, but remains high for many years. For example 10 years after removal from a reactor, the surface dose rate for

12376-412: The failure modes which occur during normal use (and the manner in which the fuel will behave during an accident) can be studied. In addition information is gained which enables the users of fuel to assure themselves of its quality and it also assists in the development of new fuels. After major accidents the core (or what is left of it) is normally subject to PIE to find out what happened. One site where PIE

12512-403: The fuel is similar to PWR fuel except that the bundles are "canned". That is, there is a thin tube surrounding each bundle. This is primarily done to prevent local density variations from affecting neutronics and thermal hydraulics of the reactor core. In modern BWR fuel bundles, there are either 91, 92, or 96 fuel rods per assembly depending on the manufacturer. A range between 368 assemblies for

12648-850: The fuel mixture for significantly extended periods, which increases fuel efficiency dramatically and incinerates the vast majority of its own waste as part of the normal operational characteristics. A downside to letting the Xe escape instead of allowing it to capture neutrons converting it to the basically stable and chemically inert Xe , is that it will quickly decay to the highly chemically reactive, long lived radioactive Cs , which behaves similar to other alkali metals and can be taken up by organisms in their metabolism. Molten salt fuels are mixtures of actinide salts (e.g. thorium/uranium fluoride/chloride) with other salts, used in liquid form above their typical melting points of several hundred degrees C. In some molten salt-fueled reactor designs, such as

12784-408: The fuel of choice for reactor designs that NASA produces. One advantage is that uranium nitride has a better thermal conductivity than UO 2 . Uranium nitride has a very high melting point. This fuel has the disadvantage that unless N was used (in place of the more common N ), a large amount of C would be generated from the nitrogen by the (n,p) reaction . As the nitrogen needed for such

12920-406: The fuel rods, standing between the coolant and the nuclear fuel. It is made of a corrosion -resistant material with low absorption cross section for thermal neutrons , usually Zircaloy or steel in modern constructions, or magnesium with small amount of aluminium and other metals for the now-obsolete Magnox reactors . Cladding prevents radioactive fission fragments from escaping the fuel into

13056-443: The fuel were thermally isolated from the hot fuel assembly by two circular thermal baffle tubes around the fuel assembly. This allowed the pressure tubes to operate at low temperatures, essentially that of the moderator tank which was maintained about 155 degrees F and close to atmospheric pressure. The moderator tank contained heavy water which moderated the fission process during operation of the reactor. The CVTR containment design

13192-532: The fuel. Accident tolerant fuels (ATF) are a series of new nuclear fuel concepts, researched in order to improve fuel performance under accident conditions, such as loss-of-coolant accident (LOCA) or reaction-initiated accidents (RIA). These concerns became more prominent after the Fukushima Daiichi nuclear disaster in Japan, in particular regarding light-water reactor (LWR) fuels performance under accident conditions. Neutronics analyses were performed for

13328-442: The heavier oxygen isotopes O and O is also commercially available. It is "heavy water" as it is denser than normal water ( H 2 O is approximately as dense as D 2 O , H 2 O is about halfway between H 2 O and D 2 O )—but is rarely called heavy water, since it does not contain the excess deuterium that gives D 2 O its unusual nuclear and biological properties. It

13464-408: The heavy water is to be used as a neutron moderator in nuclear reactors, as O can undergo neutron capture, followed by emission of an alpha particle , producing radioactive C . However, doubly labeled water , containing both a heavy oxygen and hydrogen, is useful as a non-radioactive isotopic tracer. Compared to the isotopic change of hydrogen atoms, the isotopic change of oxygen has

13600-443: The hydrogen atoms of water could be replaced with deuterium. Experiments showed that bacteria can live in 98% heavy water. Concentrations over 50% are lethal to multicellular organisms, but a few exceptions are known: plant species such as switchgrass ( Panicum virgatum ) which is able to grow on 50% D 2 O; Arabidopsis thaliana (70% D 2 O); Vesicularia dubyana (85% D 2 O); Funaria hygrometrica (90% D 2 O); and

13736-417: The impression that heavy water is normally radioactive and more severely toxic than it actually is. Even if pure heavy water had been used in the water cooler indefinitely, it is not likely the incident would have been detected or caused harm, since no employee would be expected to get much more than 25% of their daily drinking water from such a source. The most cost-effective process for producing heavy water

13872-468: The interactions between the two. Used nuclear fuel is a complex mixture of the fission products , uranium , plutonium , and the transplutonium metals . In fuel which has been used at high temperature in power reactors it is common for the fuel to be heterogeneous ; often the fuel will contain nanoparticles of platinum group metals such as palladium . Also the fuel may well have cracked, swollen, and been heated close to its melting point. Despite

14008-465: The introduction of additional absorbers. CerMet fuel consists of ceramic fuel particles (usually uranium oxide) embedded in a metal matrix. It is hypothesized that this type of fuel is what is used in United States Navy reactors. This fuel has high heat transport characteristics and can withstand a large amount of expansion. Plate-type fuel has fallen out of favor over the years. Plate-type fuel

14144-515: The need to buy heavy water. In conceptual terms, CVTR is very similar to the CANDU reactor design that was being pursued by Atomic Energy of Canada Limited around the same time. The two designs differ in some design details and that CANDU can run on natural uranium . CVTR is otherwise similar in most respects, and about the same size and power as the 22 MWe CANDU prototype which entered service in 1962. Conventional light water reactors resemble

14280-420: The neutron cross section of carbon is low, during years of burnup, the predominantly C will undergo neutron capture to produce stable C as well as radioactive C . Unlike the C produced by using uranium nitrate, the C will make up only a small isotopic impurity in the overall carbon content and thus make the entirety of the carbon content unsuitable for non-nuclear uses but

14416-700: The northeast of the existing Parr Reservoir hydroelectric dam across the Broad River on a high bluff that overlooks the dam powerhouse. The site for the CVTR was approved by the Atomic Energy Commission ’s Advisory Committee on Reactor Safeguards in January 1959. Construction started on January 1, 1960. CVRT was the first US heavy water power reactor. CVTR was operated by the Carolinas Virginia Nuclear Power Associates, which

14552-540: The plant was under German control, and the Allies decided to destroy the plant and its heavy water to inhibit German development of nuclear weapons. In late 1942, a planned raid called Operation Freshman by British airborne troops failed, both gliders crashing. The raiders were killed in the crash or subsequently executed by the Germans. Fuel rod Nuclear fuel refers to any substance, typically fissile material, which

14688-416: The plutonium in it usable for nuclear fuel but not for nuclear weapons. Reprocessing of spent commercial-reactor nuclear fuel has not been permitted in the United States due to nonproliferation considerations . All other reprocessing nations have long had nuclear weapons from military-focused research reactor fuels except for Japan. Normally, with the fuel being changed every three years or so, about half of

14824-486: The possibility of a runaway reactor meltdown, and providing an automatic load-following capability which is well suited to electricity generation and high-temperature industrial heat applications. In some liquid core designs, the fuel can be drained rapidly into a passively safe dump-tank. This advantage was conclusively demonstrated repeatedly as part of a weekly shutdown procedure during the highly successful Molten-Salt Reactor Experiment from 1965 to 1969. A liquid core

14960-442: The production of radioactive materials such as plutonium and tritium. The deuterium nucleus consists of a neutron and a proton ; the nucleus of a protium (normal hydrogen) atom consists of just a proton. The additional neutron makes a deuterium atom roughly twice as heavy as a protium atom. A molecule of heavy water has two deuterium atoms in place of the two protium atoms of ordinary water. The term heavy water as defined by

15096-413: The proportion of deuterium is greater than usual. For instance, the heavy water used in CANDU reactors is a highly enriched water mixture that is mostly deuterium oxide D 2 O , but also some hydrogen-deuterium oxide and a smaller amount of ordinary water H 2 O . It is 99.75% enriched by hydrogen atom-fraction; that is, 99.75% of the hydrogen atoms are of the heavy type; however, heavy water in

15232-477: The reactor needs to use some other form of moderator that improves the neutron economy. Several such moderators have been suggested, including carbon dioxide as in the UK Advanced Gas-cooled Reactor , liquid metals including sodium or lead as in various breeder reactors , and heavy water . Of these, heavy water has the major advantage that it is simple to work with. The downside is that it

15368-410: The reactor. Stainless steel was used in the past, but most reactors now use a zirconium alloy which, in addition to being highly corrosion-resistant, has low neutron absorption. The tubes containing the fuel pellets are sealed: these tubes are called fuel rods . The finished fuel rods are grouped into fuel assemblies that are used to build up the core of a power reactor. Cladding is the outer layer of

15504-437: The right energy to maintain the chain reaction in natural uranium fuel. This requires such designs to use enriched uranium to offset this effect, which increases the price of fuel. Using natural uranium in a reactor would offer the advantage of lowered fuel costs and better availability as the supply is not dependent on the enrichment cycle. This also offers some protection against nuclear proliferation . In order to do so,

15640-451: The same temperature. The same is true of OD vs.   OH ions. For heavy water Kw D 2 O (25.0 °C) = 1.35 × 10 , and [D  ] must equal [OD  ] for neutral water. Thus pKw D 2 O = p[OD ] + p[D ] = 7.44 + 7.44 = 14.87 (25.0 °C), and the p[D ] of neutral heavy water at 25.0 °C is 7.44. The pD of heavy water is generally measured using pH electrodes giving a pH (apparent) value, or pHa, and at various temperatures

15776-411: The smaller changes, due to isotopically influenced properties of water when it acts as a solvent . To perform their tasks, enzymes rely on their finely tuned networks of hydrogen bonds , both in the active center with their substrates and outside the active center, to stabilize their tertiary structures . As a hydrogen bond with deuterium is slightly stronger than one involving ordinary hydrogen, in

15912-496: The smallest and 800 assemblies for the largest BWR in the U.S. form the reactor core. Each BWR fuel rod is backfilled with helium to a pressure of about 3 standard atmospheres (300 kPa). Canada deuterium uranium fuel (CANDU) fuel bundles are about 0.5 metres (20 in) long and 10 centimetres (4 in) in diameter. They consist of sintered (UO 2 ) pellets in zirconium alloy tubes, welded to zirconium alloy end plates. Each bundle weighs roughly 20 kilograms (44 lb), and

16048-587: The steel pressure vessels, and the two reinforced concrete designs operated at 24.8 and 27 bars (24.5 and 26.6 atm). Magnox alloy consists mainly of magnesium with small amounts of aluminium and other metals—used in cladding unenriched uranium metal fuel with a non-oxidising covering to contain fission products. This material has the advantage of a low neutron capture cross-section, but has two major disadvantages: Magnox fuel incorporated cooling fins to provide maximum heat transfer despite low operating temperatures, making it expensive to produce. While

16184-458: The temperature goes up. Corrosion of uranium dioxide in water is controlled by similar electrochemical processes to the galvanic corrosion of a metal surface. While exposed to the neutron flux during normal operation in the core environment, a small percentage of the U in the fuel absorbs excess neutrons and is transmuted into U . U rapidly decays into Np which in turn rapidly decays into Pu . The small percentage of Pu has

16320-560: The temperature of the core increases, the reactivity decreases—so it is highly unlikely for a meltdown to occur. Most cores that use this fuel are "high leakage" cores where the excess leaked neutrons can be utilized for research. That is, they can be used as a neutron source . TRIGA fuel was originally designed to use highly enriched uranium, however in 1978 the U.S. Department of Energy launched its Reduced Enrichment for Research Test Reactors program, which promoted reactor conversion to low-enriched uranium fuel. There are 35 TRIGA reactors in

16456-449: The top directly into the fuel bundle. The fuel bundles usually are enriched several percent in U. The uranium oxide is dried before inserting into the tubes to try to eliminate moisture in the ceramic fuel that can lead to corrosion and hydrogen embrittlement . The Zircaloy tubes are pressurized with helium to try to minimize pellet-cladding interaction which can lead to fuel rod failure over long periods. In boiling water reactors (BWR),

16592-519: The tubes contained fuel enriched to 1.5% U-235 and 24 tubes contained fuel enriched to 2% U-235. During power operation, heavy water was circulated by primary pumps through the U-tubes containing the fuel assemblies which heated the water. The heated water then flowed through an inverted U-tube steam generator where the heat was transferred to the secondary side light water which turned to steam . The steam flowed to an oil-fired superheater which increased

16728-595: The turbines more efficient. In the case of a nuclear plant, the boiler is replaced with the reactor, which is more complex than a coal boiler for a number of reasons. For one, the water not only acts as the cooling fluid, but also as the neutron moderator , which means its control is vital to the operation of the system as a whole. Additionally, the water tends to pick up radioactivity from the reactor's operation, which leads to safety concerns and maintenance overhead. Finally, steam and liquid water have different moderating qualities, so most (but not all) light water designs keep

16864-407: The use of uranium metal rather than oxide made nuclear reprocessing more straightforward and therefore cheaper, the need to reprocess fuel a short time after removal from the reactor meant that the fission product hazard was severe. Expensive remote handling facilities were required to address this issue. Tristructural-isotropic (TRISO) fuel is a type of micro-particle fuel. A particle consists of

17000-558: The various differences in deuterium-containing water (especially affecting the biological properties) are larger than in any other commonly occurring isotope-substituted compound because deuterium is unique among heavy stable isotopes in being twice as heavy as the lightest isotope. This difference increases the strength of water's hydrogen–oxygen bonds, and this in turn is enough to cause differences that are important to some biochemical reactions. The human body naturally contains deuterium equivalent to about five grams of heavy water, which

17136-613: The victim ingest large amounts of heavy water without significant normal water intake for many days to produce any noticeable toxic effects. Oral doses of heavy water in the range of several grams, as well as heavy oxygen O, are routinely used in human metabolic experiments. (See doubly labeled water testing.) Since one in about every 6,400 hydrogen atoms is deuterium, a 50-kilogram (110 lb) human containing 32 kilograms (71 lb) of body water would normally contain enough deuterium (about 1.1 grams or 0.039 ounces) to make 5.5 grams (0.19 oz) of pure heavy water, so roughly this dose

17272-409: The water below the boiling point and use a steam generator to feed the turbines. The major advantage to the light water design concept is that it is simple and similar to existing systems in many ways. It has one major disadvantage, however, which is that the water removes neutrons which lowers the reactor's overall neutron economy . This is enough of an effect that there are not enough neutrons of

17408-413: The water different nuclear properties, and the increase in mass gives it slightly different physical and chemical properties when compared to normal water. Deuterium is a heavy hydrogen isotope . Heavy water contains deuterium atoms and is used in nuclear reactors . Semiheavy water (HDO) is more common than pure heavy water, while heavy-oxygen water is denser but lacks unique properties. Tritiated water

17544-424: Was a consortium of the following utilities: Carolina Power & Light Company , Duke Power Company , South Carolina Electric & Gas Company (SCE&G) , and Virginia Electric and Power Company The reactor went critical for the first time on March 30, 1963. CVTR operated successfully from 1963 to 1967. It was shut down after the completion of the planned test program. Staff : Following decommissioning of

17680-469: Was a new concept at the time; the general design later became the prevalent design for pressurized water reactor containments in the United States. Designed by Stone and Webster Engineering, the design was focused on not allowing any leakage of radioactive gases or material following an accident. The containment design featured a flat concrete foundation, cylindrical walls, and a hemispherical dome all constructed of reinforced concrete . The entire interior of

17816-553: Was also acquired from the Cominco plant in Trail, British Columbia , Canada. The Chicago Pile-3 experimental reactor used heavy water as a moderator and went critical in 1944. The three domestic production plants were shut down in 1945 after producing around 81,470 lb (36,950 kg) of product. The Wabash plant resumed heavy water production in 1952. In 1953, the United States began using heavy water in plutonium production reactors at

17952-403: Was far below levels that could induce heavy water toxicity, but several employees received elevated radiation doses from tritium and neutron-activated chemicals in the water. This was not an incident of heavy water poisoning, but rather radiation poisoning from other isotopes in the heavy water. Some news services were not careful to distinguish these points, and some of the public were left with

18088-422: Was later able to concentrate it in water. Urey's mentor Gilbert Newton Lewis isolated the first sample of pure heavy water by electrolysis in 1933. George de Hevesy and Erich Hofer used heavy water in 1934 in one of the first biological tracer experiments, to estimate the rate of turnover of water in the human body. The history of large-quantity production and use of heavy water, in early nuclear experiments,

18224-400: Was tested in two experimental reactors, LAMPRE I and LAMPRE II, at Los Alamos National Laboratory in the 1960s. LAMPRE experienced three separate fuel failures during operation. Ceramic fuels other than oxides have the advantage of high heat conductivities and melting points, but they are more prone to swelling than oxide fuels and are not understood as well. Uranium nitride is often

18360-455: Was the main producer of heavy water, using an ammonia/hydrogen exchange based plant supplied by Switzerland's Sulzer company. It was also a major exporter to Canada, Germany, the US and other countries. The heavy water production facility located in Arroyito was the world's largest heavy water production facility. Argentina produced 200 short tons (180 tonnes) of heavy water per year in 2015 using

18496-548: Was used in Soviet -designed and built RBMK -type reactors. This is a low-enriched uranium oxide fuel. The fuel elements in an RBMK are 3 m long each, and two of these sit back-to-back on each fuel channel, pressure tube. Reprocessed uranium from Russian VVER reactor spent fuel is used to fabricate RBMK fuel. Following the Chernobyl accident, the enrichment of fuel was changed from 2.0% to 2.4%, to compensate for control rod modifications and

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