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63-724: LFR can refer to: Lead-cooled fast reactor , a type of nuclear reactor LFR International , emergency medical service in Africa Lay First Responder Model , a model of emergency assistance implemented by LFR International Leavine Family Racing Lincolnshire Fire and Rescue Service in England Louisville Division of Fire , US A US Navy hull classification symbol: Inshore fire support ship (LFR) Leafs Fan Reaction, an internet series by Steve Dangle Topics referred to by

126-515: A 'lead-bismuth-cooled, or a lead-cooled, fast reactor' with two possible configurations: sub-critical or critical. It could be a pool-, or a loop-type, reactor . The project is managed by SCK CEN , the Belgian research center for nuclear energy. It is based on a first small prototype research demonstrator, the Guinevere system, derived from the zero-power reactor Venus existing at SCK CEN since

189-560: A Pressurized Water Reactor PWR ), it tends to lose kinetic energy . In contrast, if it hits a much heavier atom such as lead, the neutron will "bounce off" without losing this energy. The coolant does, however, serve as a neutron reflector , returning some escaping neutrons to the core. Smaller capacity lead-cooled fast reactors (such as SSTAR ) can be cooled by natural convection , while larger designs (such as ELSY ) use forced circulation in normal power operation, but will employ natural circulation emergency cooling. No operator interference

252-491: A curve of temperature versus current can be drawn. This curve can then be extrapolated to very high temperatures. In determining melting points of a refractory substance by this method, it is necessary to either have black body conditions or to know the emissivity of the material being measured. The containment of the high melting material in the liquid state may introduce experimental difficulties. Melting temperatures of some refractory metals have thus been measured by observing

315-482: A function of temperature. In this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer. For temperatures above the calibration range of the source, an extrapolation technique must be employed. This extrapolation is accomplished by using Planck's law of radiation. The constants in this equation are not known with sufficient accuracy, causing errors in

378-518: A liquid phase only exists above pressures of 10 MPa (99 atm) and estimated 4,030–4,430 °C (7,290–8,010 °F; 4,300–4,700 K) (see carbon phase diagram ). Hafnium carbonitride (HfCN) is a refractory compound with the highest known melting point of any substance to date and the only one confirmed to have a melting point above 4,273 K (4,000 °C; 7,232 °F) at ambient pressure. Quantum mechanical computer simulations predicted that this alloy (HfN 0.38 C 0.51 ) would have

441-415: A lot of research information derived from its experience with submarine reactors, and US interest in using Pb or Pb-Bi for small reactors has increased subsequently. The MYRRHA project (for Multi-purpose hYbrid Research Reactor for High-tech Applications ) is aimed to contribute to design a future nuclear reactor coupled to a proton accelerator (so-called Accelerator-driven system, ADS ). This could be

504-439: A melting point of about 4,400 K. This prediction was later confirmed by experiment, though a precise measurement of its exact melting point has yet to be confirmed. At the other end of the scale, helium does not freeze at all at normal pressure even at temperatures arbitrarily close to absolute zero ; a pressure of more than twenty times normal atmospheric pressure is necessary. Notes Many laboratory techniques exist for

567-605: A melting point; on heating they undergo a smooth glass transition into a viscous liquid . Upon further heating, they gradually soften, which can be characterized by certain softening points . The freezing point of a solvent is depressed when another compound is added, meaning that a solution has a lower freezing point than a pure solvent. This phenomenon is used in technical applications to avoid freezing, for instance by adding salt or ethylene glycol to water. In organic chemistry , Carnelley's rule , established in 1882 by Thomas Carnelley , states that high molecular symmetry

630-636: A metal, metal oxide or metal nitride . Reactors that use lead or lead-bismuth eutectic can be designed in a large range of power ratings. The Soviet union was able to operate the Alfa-class submarines with a lead-bismuth cooled intermediate-spectrum reactor moderated with beryllium from the 1960s to 1998, which had approximately 30 MW of mechanical output for 155 MW thermal power (see below). Other options include units featuring long-life, pre-manufactured cores, that do not require refueling for many years. The lead-cooled fast reactor battery

693-458: A metal, metal oxide or metal nitride . The lead-cooled reactor design has been proposed as a generation IV reactor . Plans for future implementation of this type of reactor include modular arrangements rated at 300 to 400 MWe, and a large monolithic plant rated at 1,200 MWe. Lead-cooled fast reactors operate with fast neutrons and molten lead or lead-bismuth eutectic coolant . Molten lead or lead-bismuth eutectic can be used as

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756-416: A pure substance is always higher and has a smaller range than the melting point of an impure substance or, more generally, of mixtures. The higher the quantity of other components, the lower the melting point and the broader will be the melting point range, often referred to as the "pasty range". The temperature at which melting begins for a mixture is known as the solidus while the temperature where melting

819-414: A quartz reflector, and lead-bismuth eutectic as coolant. The firm went out of business in 2018. The Lawrence Livermore National Laboratory developed SSTAR was a lead-cooled design. Melting point When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point . Because of the ability of substances to supercool ,

882-429: Is 234.32 kelvins (−38.83  °C ; −37.89  °F ). However, certain substances possess differing solid-liquid transition temperatures. For example, agar melts at 85 °C (185 °F; 358 K) and solidifies from 31 °C (88 °F; 304 K); such direction dependence is known as hysteresis . The melting point of ice at 1 atmosphere of pressure is very close to 0 °C (32 °F; 273 K); this

945-618: Is a small turnkey-type power plant using cassette cores running on a closed fuel cycle with 15 to 20 years' refuelling interval, or entirely replaceable reactor modules. It is designed for generation of electricity on small grids (and other resources, including hydrogen production and desalinisation process for the production of potable water ). The use of lead as a coolant has several advantages if compared to other methods for reactor cooling. Two types of lead-cooled reactor were used in Soviet Alfa-class submarines of

1008-512: Is also discontinued. Beside continuously increasing costs and financial uncertainties, the project still has to address many technical challenges: severe corrosion issues ( liquid metal embrittlement , amalgam -driven dissolution in the molten metal of Cr and Ni from the stainless steel used for the fuel claddings and reactor structure materials), operating temperature (metal solidification risks versus increased corrosion rate), nuclear criticality safety issues... The mass inventory of

1071-622: Is also known as the ice point. In the presence of nucleating substances , the freezing point of water is not always the same as the melting point. In the absence of nucleators water can exist as a supercooled liquid down to −48.3 °C (−54.9 °F; 224.8 K) before freezing. The metal with the highest melting point is tungsten , at 3,414 °C (6,177 °F; 3,687 K); this property makes tungsten excellent for use as electrical filaments in incandescent lamps . The often-cited carbon does not melt at ambient pressure but sublimes at about 3,700 °C (6,700 °F; 4,000 K);

1134-428: Is associated with high melting point . Carnelley based his rule on examination of 15,000 chemical compounds. For example, for three structural isomers with molecular formula C 5 H 12 the melting point increases in the series isopentane −160 °C (113 K) n-pentane −129.8 °C (143 K) and neopentane −16.4 °C (256.8 K). Likewise in xylenes and also dichlorobenzenes the melting point increases in

1197-425: Is complete is called the liquidus . Eutectics are special types of mixtures that behave like single phases. They melt sharply at a constant temperature to form a liquid of the same composition. Alternatively, on cooling a liquid with the eutectic composition will solidify as uniformly dispersed, small (fine-grained) mixed crystals with the same composition. In contrast to crystalline solids, glasses do not possess

1260-557: Is currently under construction. This reactor will employ pure lead as coolant, a plutonium/uranium nitride fuel, generate 300 MWe (electric) from 750 MWth, and is a pool type reactor. The foundation has been completed in November 2021. The reactor sits as the Siberian Chemical Combine's (SCC's) Seversk site. The company LeadCold is in collaboration with KTH Royal Institute of Technology and Uniper developing

1323-556: Is different from Wikidata All article disambiguation pages All disambiguation pages Lead-cooled fast reactor The lead-cooled fast reactor is a nuclear reactor design that uses molten lead or lead-bismuth eutectic coolant . These materials can be used as the primary coolant because they have low neutron absorption and relatively low melting points . Neutrons are slowed less by interaction with these heavy nuclei (thus not being neutron moderators ) so these reactors operate with fast neutrons . The concept

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1386-660: Is generally similar to sodium-cooled fast reactors , and most liquid-metal fast reactors have used sodium instead of lead. Few lead-cooled reactors have been constructed, except for the Soviet submarine K-27 and all 7 of the Soviet Alfa-class submarines (though these were beryllium -moderated intermediate energy reactors rather than fast reactors). However, a number of proposed and one in construction new nuclear reactor designs are lead-cooled. Fuel designs being explored for this reactor scheme include fertile uranium as

1449-420: Is generally very similar to sodium-cooled fast reactor , and most liquid-metal fast reactors have used sodium instead of lead. Few lead-cooled reactors have been constructed, except for some Soviet nuclear submarine reactors in the 1970s, but a number of proposed and one in construction new nuclear reactor designs are lead-cooled. Fuel designs being explored for this reactor scheme include fertile uranium as

1512-467: Is required, nor pumping of any kind to cool the residual heat of the reactor after shutdown. The reactor outlet coolant temperature is typically in the range of 500 to 600 °C, possibly ranging over 800 °C with advanced materials for later designs. Temperatures higher than 800 °C are theoretically high enough to support thermochemical production of hydrogen through the sulfur-iodine cycle , although this has not been demonstrated. The concept

1575-437: Is sensitive to extremely large changes in pressure , but generally this sensitivity is orders of magnitude less than that for the boiling point , because the solid-liquid transition represents only a small change in volume. If, as observed in most cases, a substance is more dense in the solid than in the liquid state, the melting point will increase with increases in pressure. Otherwise the reverse behavior occurs. Notably, this

1638-520: Is the atomic mass , ν is the frequency , u is the average vibration amplitude, k B is the Boltzmann constant , and T is the absolute temperature . If the threshold value of u is c a where c is the Lindemann constant and a is the atomic spacing , then the melting point is estimated as Several other expressions for the estimated melting temperature can be obtained depending on

1701-478: Is the case of water, as illustrated graphically to the right, but also of Si, Ge, Ga, Bi. With extremely large changes in pressure, substantial changes to the melting point are observed. For example, the melting point of silicon at ambient pressure (0.1 MPa) is 1415 °C, but at pressures in excess of 10 GPa it decreases to 1000 °C. Melting points are often used to characterize organic and inorganic compounds and to ascertain their purity . The melting point of

1764-498: The Pu handling, or to be completely performed by remotely-operated robots. An envisaged mitigation strategy could consist into a continuous removal of polonium from LBE, but the considerable heat generated by Po represents a major obstacle. In 2023, based on interviews with key SCK CEN players and documents publicly available, Hein Brookhuis explored the interactions between

1827-676: The SEALER (Swedish Advanced Lead Reactor) reactor, a lead-cooled reactor using uranium nitride as fuel. British company Newcleo is developing 30 MWe and 200 MWe lead-cooled small modular reactors for naval and land use. The first operational reactor is planned to be deployed in 2030 in France. The initial design of the Hyperion Power Module was to be of this type, using uranium nitride fuel encased in HT-9 tubes, using

1890-606: The Wayback Machine was announced in 2010 to develop a commercial lead-bismuth reactor. The SVBR-100 ('Svintsovo-Vismutovyi Bystryi Reaktor' - lead-bismuth fast reactor) is based on the Alfa designs and will produce 100MWe electricity from gross thermal power of 280MWt, about twice that of the submarine reactors. They can also be used in groups of up to 16 if more power is required. The coolant increases from 345 °C (653 °F) to 495 °C (923 °F) as it goes through

1953-492: The entropy ( S ) of the material are increasing (ΔH, ΔS > 0). Melting phenomenon happens when the Gibbs free energy of the liquid becomes lower than the solid for that material. At various pressures this happens at a specific temperature. It can also be shown that: Here T , ΔS and ΔH are respectively the temperature at the melting point, change of entropy of melting and the change of enthalpy of melting. The melting point

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2016-476: The 1970s. The OK-550 and BM-40A designs were both capable of producing 155MWt. They were significantly lighter than typical water-cooled reactors and had an advantage of being capable to quickly switch between maximum power and minimum noise operation modes. . Notably, these included a beryllium moderator and were therefore not fast-neutron reactors, but rather intermediate-neutron reactors. A joint venture called AKME Engineering Archived 24 December 2018 at

2079-543: The FEED activities were published in a journal absolutely not related to the field of ADS or fast neutron reactor: the International Journal of Hydrogen Energy (IJHE) while there was never any question of producing hydrogen with MYRRHA. The choice of this journal to present the preliminary results of the FEED activities is disconcerting. The journal where the FEED activities were announced, Physics Procedia ,

2142-582: The MYRRHA nuclear fuel. Because of the high volatility of Po , the plenum space above the reactor could also become alpha-contaminated. As pointed out by Fiorito et al. (2018): "Some polonium will migrate to the cover gas in the reactor plenum and will diffuse outside the primary system when the reactor is opened for refueling or maintenance". All operations in Po contaminated areas will require appropriate radiological protection measures much more severe than for

2205-511: The MYRRHA promoters and the Belgian media and political spheres to show how MYRRHA was developed in a narrative that made the project seems essential to the future of SCK CEN, the Belgian nuclear research center. The dual fluid reactor (DFR) project was initially developed by a German research institute, the Institute for Solid-State Nuclear Physics, in Berlin. In February 2021, the project

2268-401: The amplitude of vibration becomes large enough for adjacent atoms to partly occupy the same space. The Lindemann criterion states that melting is expected when the vibration root mean square amplitude exceeds a threshold value. Assuming that all atoms in a crystal vibrate with the same frequency ν , the average thermal energy can be estimated using the equipartition theorem as where m

2331-643: The analysis of crystalline solids consists of an oil bath with a transparent window (most basic design: a Thiele tube ) and a simple magnifier. Several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated (and stirred) and with the aid of the magnifier (and external light source) melting of the individual crystals at a certain temperature can be observed. A metal block might be used instead of an oil bath. Some modern instruments have automatic optical detection. The measurement can also be made continuously with an operating process. For instance, oil refineries measure

2394-483: The beginning of the 1960s and modified to host a bath of molten lead-bismuth eutectic (LBE) coupled to a small proton accelerator . In December 2010, MYRRHA was listed by the European Commission as one of 50 projects for maintaining European leadership in nuclear research in the next 20 years. In 2013, the project entered a further development phase when a contract for the front-end engineering design

2457-455: The container. For a solid to melt, heat is required to raise its temperature to the melting point. However, further heat needs to be supplied for the melting to take place: this is called the heat of fusion , and is an example of latent heat . From a thermodynamics point of view, at the melting point the change in Gibbs free energy (ΔG) of the material is zero, but the enthalpy ( H ) and

2520-480: The core. Uranium oxide enriched to 16.5% U-235 could be used as fuel, and refuelling would be required every 7–8 years. A prototype is planned for 2017. Another two lead-cooled fast reactors are developed by Russians: BREST-300 and BREST-1200 . The BREST-300 design was completed in September 2014. WNA mentions Russia role on boosting other countries interest in this field: In 1998, Russia declassified

2583-413: The crystal phase is densely packed with many efficient intermolecular interactions resulting in a higher enthalpy change on melting. An attempt to predict the bulk melting point of crystalline materials was first made in 1910 by Frederick Lindemann . The idea behind the theory was the observation that the average amplitude of thermal vibrations increases with increasing temperature. Melting initiates when

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2646-515: The darkening of the hole when the liquid phase appears, destroying the black body conditions. Today, containerless laser heating techniques, combined with fast pyrometers and spectro-pyrometers, are employed to allow for precise control of the time for which the sample is kept at extreme temperatures. Such experiments of sub-second duration address several of the challenges associated with more traditional melting point measurements made at very high temperatures, such as sample vaporization and reaction with

2709-414: The determination of melting points. A Kofler bench is a metal strip with a temperature gradient (range from room temperature to 300 °C). Any substance can be placed on a section of the strip, revealing its thermal behaviour at the temperature at that point. Differential scanning calorimetry gives information on melting point together with its enthalpy of fusion . A basic melting point apparatus for

2772-853: The estimate of the average thermal energy. Another commonly used expression for the Lindemann criterion is From the expression for the Debye frequency for ν , where θ D is the Debye temperature and h is the Planck constant . Values of c range from 0.15 to 0.3 for most materials. In February 2011, Alfa Aesar released over 10,000 melting points of compounds from their catalog as open data and similar data has been mined from patents . The Alfa Aesar and patent data have been summarized in (respectively) random forest and support vector machines . Primordial   From decay   Synthetic   Border shows natural occurrence of

2835-408: The extrapolation to become larger at higher temperatures. However, standard techniques have been developed to perform this extrapolation. Consider the case of using gold as the source (mp = 1,063 °C). In this technique, the current through the filament of the pyrometer is adjusted until the light intensity of the filament matches that of a black-body at the melting point of gold. This establishes

2898-560: The factory. In 2009, under the auspices of the Nuclear Energy Agency (NEA, OECD ), an international team of experts (MYRRHA International Review Team, MIRT) examined the MYRRHA project and delivered prudent recommendations to the Belgian government . Beside the technical challenges identified, they were also financial and economical risks related to the construction and exploitation costs expected to strongly increase when

2961-464: The freeze point of diesel fuel "online", meaning that the sample is taken from the process and measured automatically. This allows for more frequent measurements as the sample does not have to be manually collected and taken to a remote laboratory. For refractory materials (e.g. platinum, tungsten, tantalum, some carbides and nitrides, etc.) the extremely high melting point (typically considered to be above, say, 1,800 °C) may be determined by heating

3024-435: The freezing point can easily appear to be below its actual value. When the "characteristic freezing point" of a substance is determined, in fact, the actual methodology is almost always "the principle of observing the disappearance rather than the formation of ice, that is, the melting point ." For most substances, melting and freezing points are approximately equal. For example, the melting and freezing points of mercury

3087-486: The high thermal conductivity of the molten metal, the residual decay heat of a DFR reactor could be passively removed. ALFRED (Advanced Lead Fast Reactor European Demonstrator) is a lead cooled fast reactor demonstrator designed by Ansaldo Energia from Italy planned to be built in Mioveni, Romania. ATHENA, a molten lead pool used for research purposes, is going to be built in the same site as well. The BREST reactor

3150-460: The lead-bismuth eutectic (LBE) for the proposed pool-type design of MYRRHA considered in the preliminary FEED analyses of 2013-2015 represents 4500 tons metallic Pb-Bi. This would lead to the production of more than 4 kg of Po during the reactor operations. After the first operating cycle, 350 g of Po would already be formed in the LBE exposed to a high neutron flux of

3213-425: The material in a black body furnace and measuring the black-body temperature with an optical pyrometer . For the highest melting materials, this may require extrapolation by several hundred degrees. The spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as

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3276-558: The non-proliferation requirements imposed to new test reactors by the RERTR (Reduced Enrichment of fuel for Research Testing Reactors) program launched by US DOE in 1996". So, the fuel to be selected for MYRRHA also needs to respect the criteria of non-proliferation while keeping its neutronic performance. Moreover, such a highly enriched MOx fuel has never been industrially produced and poses severe technical and safety challenges in order to prevent any criticality accident during handling in

3339-443: The order meta, ortho and then para . Pyridine has a lower symmetry than benzene hence its lower melting point but the melting point again increases with diazine and triazines . Many cage-like compounds like adamantane and cubane with high symmetry have relatively high melting points. A high melting point results from a high heat of fusion , a low entropy of fusion , or a combination of both. In highly symmetrical molecules

3402-413: The order of 10 neutrons・cm ・s , typical for a materials testing reactor (MTR). This would correspond to an activity of 5.5 × 10 becquerels , or 1.49 × 10 curies of Po , just for the first operation cycle. The presence of such a large ponderable quantity of highly radiotoxic Po represents a considerable radiological safety challenge for the maintenance operations and the storage of

3465-410: The primary calibration temperature and can be expressed in terms of current through the pyrometer lamp. With the same current setting, the pyrometer is sighted on another black-body at a higher temperature. An absorbing medium of known transmission is inserted between the pyrometer and this black-body. The temperature of the black-body is then adjusted until a match exists between its intensity and that of

3528-406: The primary coolant because especially lead, and to a lesser degree bismuth have low neutron absorption and relatively low melting points . Neutrons are slowed less by interaction with these heavy nuclei (thus not being neutron moderators ) and therefore, help make this type of reactor a fast-neutron reactor . In simple terms, if a neutron hits a particle with a similar mass (such as hydrogen in

3591-527: The project should enter a more detailed design stage. Long construction delays related to design complications, underestimated technical difficulties and insufficient budget are not uncommon for such a project. The limited participation of the Belgian State (40% of all the costs) and the uncertain benefits for the external project owners were also pointed out. Because of recurrent financial shortcomings and also important uncertainties still subsisting in

3654-470: The pyrometer filament. The true higher temperature of the black-body is then determined from Planck's Law. The absorbing medium is then removed and the current through the filament is adjusted to match the filament intensity to that of the black-body. This establishes a second calibration point for the pyrometer. This step is repeated to carry the calibration to higher temperatures. Now, temperatures and their corresponding pyrometer filament currents are known and

3717-407: The radiation from a black body cavity in solid metal specimens that were much longer than they were wide. To form such a cavity, a hole is drilled perpendicular to the long axis at the center of a rod of the material. These rods are then heated by passing a very large current through them, and the radiation emitted from the hole is observed with an optical pyrometer. The point of melting is indicated by

3780-448: The reactor design ( pool-, or loop-type, reactor ?) and the choice still to be made for the liquid metal coolant (in LBE , Bi is neutron activated producing the highly radiotoxic ⍺-emitting Po ) the front-end engineering design (FEED) activities had to be suspended and have not progressed beyond the preliminary stage. Quite surprisingly, the preliminary results of

3843-403: The same term [REDACTED] This disambiguation page lists articles associated with the title LFR . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=LFR&oldid=1191624821 " Category : Disambiguation pages Hidden categories: Short description

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3906-569: Was awarded to a consortium led by Areva . Aiming at a compact core with high power density ( i.e. with a high neutron flux ) to be able to operate as a materials testing reactor , the fuel to be used in the ADS MYRRHA must be highly enriched in a fissile isotope . A highly enriched MOx fuel with 30 – 35 wt. % of Pu was first selected to obtain the desired neutronic performances. However, according to Abderrahim et al. (2005) "this choice should still be checked against

3969-415: Was transferred to a newly founded Canadian company, Dual Fluid Energy Inc., to industrialize the concept. The DFR project attempts to combine the advantages of the molten salt reactor with these of the liquid metal cooled reactor . As a fast breeder reactor, the proposed DFR reactor is designed to burn both natural uranium or thorium , as well as transmutating and fissioning minor actinides . Due to

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