117-552: 12°33′44″N 80°09′52″E / 12.5623504°N 80.1645415°E / 12.5623504; 80.1645415 The Fast Breeder Test Reactor ( FBTR ) is a breeder reactor located at Kalpakkam , Tamil Nadu , India . The Indira Gandhi Center for Atomic Research ( IGCAR ) and Bhabha Atomic Research Centre (BARC) jointly designed, constructed, and operate the reactor. It first reached criticality in October ;1985 (39 years ago) ( 1985-10 ) , making India
234-433: A chain reaction , as well as the ratio of breeding to fission. On the other hand, a fast reactor needs no moderator to slow down the neutrons at all, taking advantage of the fast neutrons producing a greater number of neutrons per fission than slow neutrons. For this reason ordinary liquid water , being a moderator and neutron absorber , is an undesirable primary coolant for fast reactors. Because large amounts of water in
351-417: A laser enrichment process known as SILEX ( separation of isotopes by laser excitation ), which it intends to pursue through financial investment in a U.S. commercial venture by General Electric, Although SILEX has been granted a license to build a plant, the development is still in its early stages as laser enrichment has yet to be proven to be economically viable, and there is a petition being filed to review
468-480: A 20% or higher concentration of U. This high enrichment level is essential for nuclear weapons and certain specialized reactor designs. The fissile uranium in nuclear weapon primaries usually contains 85% or more of U known as weapons grade , though theoretically for an implosion design , a minimum of 20% could be sufficient (called weapon-usable) although it would require hundreds of kilograms of material and "would not be practical to design"; even lower enrichment
585-460: A blend of uranium, plutonium, and zirconium (used because it is "transparent" to neutrons). Enriched uranium can be used on its own. Many designs surround the reactor core in a blanket of tubes that contain non-fissile uranium-238, which, by capturing fast neutrons from the reaction in the core, converts to fissile plutonium-239 (as is some of the uranium in the core), which is then reprocessed and used as nuclear fuel. Other FBR designs rely on
702-773: A blendstock to dilute the unwanted byproducts that may be contained in the HEU feed. Concentrations of these isotopes in the LEU product in some cases could exceed ASTM specifications for nuclear fuel if NU or DU were used. So, the HEU downblending generally cannot contribute to the waste management problem posed by the existing large stockpiles of depleted uranium. Effective management and disposition strategies for depleted uranium are crucial to ensure long-term safety and environmental protection. Innovative approaches such as reprocessing and recycling of depleted uranium could offer sustainable solutions to minimize waste and optimize resource utilization in
819-455: A breeder reactor then needs to be reprocessed to remove those neutron poisons . This step is required to fully utilize the ability to breed as much or more fuel than is consumed. All reprocessing can present a proliferation concern, since it can extract weapons-usable material from spent fuel. The most common reprocessing technique, PUREX , presents a particular concern since it was expressly designed to separate plutonium. Early proposals for
936-535: A chain reaction), fission products are viewed as nuclear 'ashes' left over from consuming fissile materials. Furthermore, only seven long-lived fission product isotopes have half-lives longer than a hundred years, which makes their geological storage or disposal less problematic than for transuranic materials. With increased concerns about nuclear waste, breeding fuel cycles came under renewed interest as they can reduce actinide wastes, particularly plutonium and minor actinides. Breeder reactors are designed to fission
1053-538: A fission reactor. Breeder reactors by design have high burnup compared to a conventional reactor, as breeder reactors produce more of their waste in the form of fission products, while most or all of the actinides are meant to be fissioned and destroyed. In the past, breeder-reactor development focused on reactors with low breeding ratios, from 1.01 for the Shippingport Reactor running on thorium fuel and cooled by conventional light water to over 1.2 for
1170-416: A half-life between 91 and 200,000 years. As a result of this physical oddity, after several hundred years in storage, the activity of the radioactive waste from an FBR would quickly drop to the low level of the long-lived fission products . However, to obtain this benefit requires the highly efficient separation of transuranics from spent fuel. If the fuel reprocessing methods used leave a large fraction of
1287-1190: A heavily moderated thermal design, evolved into the fast reactor concept, using light water in a low-density supercritical form to increase the neutron economy enough to allow breeding. Aside from water-cooled, there are many other types of breeder reactor currently envisioned as possible. These include molten-salt cooled , gas cooled , and liquid-metal cooled designs in many variations. Almost any of these basic design types may be fueled by uranium , plutonium , many minor actinides , or thorium , and they may be designed for many different goals, such as creating more fissile fuel, long-term steady-state operation, or active burning of nuclear wastes . Extant reactor designs are sometimes divided into two broad categories based upon their neutron spectrum, which generally separates those designed to use primarily uranium and transuranics from those designed to use thorium and avoid transuranics. These designs are: All current large-scale FBR power stations were liquid metal fast breeder reactors (LMFBR) cooled by liquid sodium . These have been of one of two designs: There are only two commercially operating breeder reactors as of 2017 :
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#17327719632951404-457: A light-water reactor for longer than 100,000 years, the transuranics would be the main source of radioactivity. Eliminating them would eliminate much of the long-term radioactivity from the spent fuel. In principle, breeder fuel cycles can recycle and consume all actinides, leaving only fission products. As the graphic in this section indicates, fission products have a peculiar "gap" in their aggregate half-lives, such that no fission products have
1521-409: A mix of ions . France developed its own version of PSP, which it called RCI. Funding for RCI was drastically reduced in 1986, and the program was suspended around 1990, although RCI is still used for stable isotope separation. "Separative work"—the amount of separation done by an enrichment process—is a function of the concentrations of the feedstock, the enriched output, and the depleted tailings; and
1638-525: A negatively charged plate and collected. Molecular laser isotope separation uses an infrared laser directed at UF 6 , exciting molecules that contain a U atom. A second laser frees a fluorine atom, leaving uranium pentafluoride , which then precipitates out of the gas. Separation of isotopes by laser excitation is an Australian development that also uses UF 6 . After a protracted development process involving U.S. enrichment company USEC acquiring and then relinquishing commercialization rights to
1755-500: A particular vortex tube separator design, and both embodied in industrial plant. A demonstration plant was built in Brazil by NUCLEI, a consortium led by Industrias Nucleares do Brasil that used the separation nozzle process. However, all methods have high energy consumption and substantial requirements for removal of waste heat; none is currently still in use. In the electromagnetic isotope separation process (EMIS), metallic uranium
1872-419: A prototype. Uranium enrichment Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written U) has been increased through the process of isotope separation . Naturally occurring uranium is composed of three major isotopes: uranium-238 ( U with 99.2732–99.2752% natural abundance ), uranium-235 ( U, 0.7198–0.7210%), and uranium-234 ( U, 0.0049–0.0059%). U
1989-419: A reactor's performance is the "conversion ratio", defined as the ratio of new fissile atoms produced to fissile atoms consumed. All proposed nuclear reactors except specially designed and operated actinide burners experience some degree of conversion. As long as there is any amount of a fertile material within the neutron flux of the reactor, some new fissile material is always created. When the conversion ratio
2106-433: A significant contributor to global energy security and environmental sustainability, effectively repurposing material once intended for destructive purposes into a resource for peaceful energy production. The United States Enrichment Corporation has been involved in the disposition of a portion of the 174.3 tonnes of highly enriched uranium (HEU) that the U.S. government declared as surplus military material in 1996. Through
2223-592: A third of the world's thorium reserves are in India, which lacks significant uranium reserves. The third and final core of the Shippingport Atomic Power Station 60 MWe reactor was a light water thorium breeder, which began operating in 1977. It used pellets made of thorium dioxide and uranium-233 oxide; initially, the U-233 content of the pellets was 5–6% in the seed region, 1.5–3% in
2340-566: A thorium thermal breeder. Liquid-fluoride reactors may have attractive features, such as inherent safety, no need to manufacture fuel rods, and possibly simpler reprocessing of the liquid fuel. This concept was first investigated at the Oak Ridge National Laboratory Molten-Salt Reactor Experiment in the 1960s. From 2012 it became the subject of renewed interest worldwide. Breeder reactors could, in principle, extract almost all of
2457-410: Is a minor isotope contained in natural uranium (primarily as a product of alpha decay of U —because the half-life of U is much larger than that of U , it is be produced and destroyed at the same rate in a constant steady state equilibrium, bringing any sample with sufficient U content to a stable ratio of U to U over long enough timescales); during
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#17327719632952574-520: Is a product of nuclear fuel cycles involving nuclear reprocessing of spent fuel . RepU recovered from light water reactor (LWR) spent fuel typically contains slightly more U than natural uranium , and therefore could be used to fuel reactors that customarily use natural uranium as fuel, such as CANDU reactors . It also contains the undesirable isotope uranium-236 , which undergoes neutron capture , wasting neutrons (and requiring higher U enrichment) and creating neptunium-237 , which would be one of
2691-534: Is a very effective and cheap method of uranium separation, able to be done in small facilities requiring much less energy and space than previous separation techniques. The cost of uranium enrichment using laser enrichment technologies is approximately $ 30 per SWU which is less than a third of the price of gas centrifuges, the current standard of enrichment. Separation of isotopes by laser excitation could be done in facilities virtually undetectable by satellites. More than 20 countries have worked with laser separation over
2808-440: Is approximately 100 dollars per Separative Work Units (SWU), making it about 40% cheaper than standard gaseous diffusion techniques. The Zippe-type centrifuge is an improvement on the standard gas centrifuge, the primary difference being the use of heat. The bottom of the rotating cylinder is heated, producing convection currents that move the U up the cylinder, where it can be collected by scoops. This improved centrifuge design
2925-404: Is being done that would use nuclear resonance ; however, there is no reliable evidence that any nuclear resonance processes have been scaled up to production. Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride ( hex ) through semi-permeable membranes . This produces a slight separation between the molecules containing U and U. Throughout
3042-437: Is compressed by the primary nuclear explosion often uses HEU with enrichment between 40% and 80% along with the fusion fuel lithium deuteride . This multi-stage design enhances the efficiency and effectiveness of nuclear weapons, allowing for greater control over the release of energy during detonation. For the secondary of a large nuclear weapon, the higher critical mass of less-enriched uranium can be an advantage as it allows
3159-408: Is crucial for optimizing the economic and operational performance of uranium enrichment facilities. In addition to the separative work units provided by an enrichment facility, the other important parameter to be considered is the mass of natural uranium (NU) that is needed to yield a desired mass of enriched uranium. As with the number of SWUs, the amount of feed material required will also depend on
3276-564: Is due to the nation's large reserves, though known worldwide reserves of thorium are four times those of uranium. India's Department of Atomic Energy said in 2007 that it would simultaneously construct four more breeder reactors of 500 MWe each including two at Kalpakkam . BHAVINI , an Indian nuclear power company, was established in 2003 to construct, commission, and operate all stage II fast breeder reactors outlined in India's three-stage nuclear power programme . To advance these plans,
3393-403: Is enough fuel for breeder reactors to satisfy the world's energy needs for 5 billion years at 1983's total energy consumption rate, thus making nuclear energy effectively a renewable energy . In addition to seawater, the average crustal granite rocks contain significant quantities of uranium and thorium that with breeder reactors can supply abundant energy for the remaining lifespan of the sun on
3510-640: Is expressed in units that are so calculated as to be proportional to the total input (energy / machine operation time) and to the mass processed. Separative work is not energy. The same amount of separative work will require different amounts of energy depending on the efficiency of the separation technology. Separative work is measured in Separative work units SWU, kg SW, or kg UTA (from the German Urantrennarbeit – literally uranium separation work ). Efficient utilization of separative work
3627-514: Is first vaporized, and then ionized to positively charged ions. The cations are then accelerated and subsequently deflected by magnetic fields onto their respective collection targets. A production-scale mass spectrometer named the Calutron was developed during World War II that provided some of the U used for the Little Boy nuclear bomb, which was dropped over Hiroshima in 1945. Properly
Fast Breeder Test Reactor - Misplaced Pages Continue
3744-457: Is further processed to obtain the desired form of uranium suitable for nuclear fuel production. After the milling process is complete, the uranium must next undergo a process of conversion, "to either uranium dioxide , which can be used as the fuel for those types of reactors that do not require enriched uranium, or into uranium hexafluoride , which can be enriched to produce fuel for the majority of types of reactors". Naturally occurring uranium
3861-457: Is greater than 1, it is often called the "breeding ratio". For example, commonly used light water reactors have a conversion ratio of approximately 0.6. Pressurized heavy-water reactors running on natural uranium have a conversion ratio of 0.8. In a breeder reactor, the conversion ratio is higher than 1. "Break-even" is achieved when the conversion ratio reaches 1.0 and the reactor produces as much fissile material as it uses. The doubling time
3978-518: Is hypothetically possible, but as the enrichment percentage decreases the critical mass for unmoderated fast neutrons rapidly increases, with for example, an infinite mass of 5.4% U being required. For criticality experiments, enrichment of uranium to over 97% has been accomplished. The first uranium bomb, Little Boy , dropped by the United States on Hiroshima in 1945, used 64 kilograms (141 lb) of 80% enriched uranium. Wrapping
4095-477: Is known as depleted uranium (DU), and is considerably less radioactive than even natural uranium, though still very dense. Depleted uranium is used as a radiation shielding material and for armor-penetrating weapons . Uranium as it is taken directly from the Earth is not suitable as fuel for most nuclear reactors and requires additional processes to make it usable ( CANDU design is a notable exception). Uranium
4212-435: Is lost during manufacturing. The opposite of enriching is downblending; surplus HEU can be downblended to LEU to make it suitable for use in commercial nuclear fuel. Downblending is a key process in nuclear non-proliferation efforts, as it reduces the amount of highly enriched uranium available for potential weaponization while repurposing it for peaceful purposes. The HEU feedstock can contain unwanted uranium isotopes: U
4329-399: Is made of a mixture of U and U. The U is fissile , meaning it is easily split with neutrons while the remainder is U, but in nature, more than 99% of the extracted ore is U. Most nuclear reactors require enriched uranium, which is uranium with higher concentrations of U ranging between 3.5% and 4.5% (although a few reactor designs using a graphite or heavy water moderator , such as
4446-469: Is mined either underground or in an open pit depending on the depth at which it is found. After the uranium ore is mined, it must go through a milling process to extract the uranium from the ore. This is accomplished by a combination of chemical processes with the end product being concentrated uranium oxide, which is known as " yellowcake ", contains roughly 80% uranium whereas the original ore typically contains as little as 0.1% uranium. This yellowcake
4563-606: Is not usable in thermal neutron reactors but can be chemically separated from spent fuel to be disposed of as waste or to be transmutated into Pu (for use in nuclear batteries ) in special reactors. Understanding and managing the isotopic composition of uranium during downblending processes is essential to ensure the quality and safety of the resulting nuclear fuel, as well as to mitigate potential radiological and proliferation risks associated with unwanted isotopes. The blendstock can be NU or DU; however, depending on feedstock quality, SEU at typically 1.5 wt% U may be used as
4680-690: Is only 1.26% lighter than U.) This problem is compounded because uranium is rarely separated in its atomic form, but instead as a compound ( UF 6 is only 0.852% lighter than UF 6 ). A cascade of identical stages produces successively higher concentrations of U. Each stage passes a slightly more concentrated product to the next stage and returns a slightly less concentrated residue to the previous stage. There are currently two generic commercial methods employed internationally for enrichment: gaseous diffusion (referred to as first generation) and gas centrifuge ( second generation), which consumes only 2% to 2.5% as much energy as gaseous diffusion. Some work
4797-440: Is the amount of time it would take for a breeder reactor to produce enough new fissile material to replace the original fuel and additionally produce an equivalent amount of fuel for another nuclear reactor. This was considered an important measure of breeder performance in early years, when uranium was thought to be scarce. However, since uranium is more abundant than thought in the early days of nuclear reactor development, and given
Fast Breeder Test Reactor - Misplaced Pages Continue
4914-466: Is the only nuclide existing in nature (in any appreciable amount) that is fissile with thermal neutrons . Enriched uranium is a critical component for both civil nuclear power generation and military nuclear weapons . There are about 2,000 tonnes of highly enriched uranium in the world, produced mostly for nuclear power , nuclear weapons, naval propulsion , and smaller quantities for research reactors . The U remaining after enrichment
5031-445: Is transuranics (atoms heavier than uranium), which are generated from uranium or heavier atoms in the fuel when they absorb neutrons but do not undergo fission. All transuranic isotopes fall within the actinide series on the periodic table , and so they are frequently referred to as the actinides. The largest component is the remaining uranium which is around 98.25% uranium-238, 1.1% uranium-235, and 0.65% uranium-236. The U-236 comes from
5148-487: Is used commercially by Urenco to produce nuclear fuel and was used by Pakistan in their nuclear weapons program. Laser processes promise lower energy inputs, lower capital costs and lower tails assays, hence significant economic advantages. Several laser processes have been investigated or are under development. Separation of isotopes by laser excitation (SILEX) is well developed and is licensed for commercial operation as of 2012. Separation of isotopes by laser excitation
5265-400: The activity of the waste is about the same as that produced by a light-water reactor. Waste from a breeder reactor has a different decay behavior because it is made up of different materials. Breeder reactor waste is mostly fission products, while light-water reactor waste is mostly unused uranium isotopes and a large quantity of transuranics. After spent nuclear fuel has been removed from
5382-616: The American Physical Society filed a petition with the NRC, asking that before any laser excitation plants are built that they undergo a formal review of proliferation risks. The APS even went as far as calling the technology a "game changer" due to the ability for it to be hidden from any type of detection. Aerodynamic enrichment processes include the Becker jet nozzle techniques developed by E. W. Becker and associates using
5499-531: The BN-600 reactor , at 560 MWe, and the BN-800 reactor , at 880 MWe. Both are Russian sodium-cooled reactors. The designs use liquid metal as the primary coolant, to transfer heat from the core to steam used to power the electricity generating turbines. FBRs have been built cooled by liquid metals other than sodium—some early FBRs used mercury ; other experimental reactors have used a sodium-potassium alloy . Both have
5616-476: The Chinese Academy of Sciences annual conference in 2011. Its ultimate target was to investigate and develop a thorium-based molten salt nuclear system over about 20 years. South Korea is developing a design for a standardized modular FBR for export, to complement the standardized pressurized water reactor and CANDU designs they have already developed and built, but has not yet committed to building
5733-556: The Cold War , gaseous diffusion played a major role as a uranium enrichment technique, and as of 2008 accounted for about 33% of enriched uranium production, but in 2011 was deemed an obsolete technology that is steadily being replaced by the later generations of technology as the diffusion plants reach their ends of life. In 2013, the Paducah facility in the U.S. ceased operating, it was the last commercial U gaseous diffusion plant in
5850-453: The FBR-600 is a pool-type sodium-cooled reactor with a rating of 600 MWe. The China Experimental Fast Reactor is a 25 MW(e) prototype for the planned China Prototype Fast Reactor. It started generating power in 2011. China initiated a research and development project in thorium molten-salt thermal breeder-reactor technology (liquid fluoride thorium reactor), formally announced at
5967-693: The International Panel on Fissile Materials said "After six decades and the expenditure of the equivalent of tens of billions of dollars, the promise of breeder reactors remains largely unfulfilled and efforts to commercialize them have been steadily cut back in most countries". In Germany, the United Kingdom, and the United States, breeder reactor development programs have been abandoned. The rationale for pursuing breeder reactors—sometimes explicit and sometimes implicit—was based on
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#17327719632956084-472: The LIGA process and the vortex tube separation process. These aerodynamic separation processes depend upon diffusion driven by pressure gradients, as does the gas centrifuge. They in general have the disadvantage of requiring complex systems of cascading of individual separating elements to minimize energy consumption. In effect, aerodynamic processes can be considered as non-rotating centrifuges. Enhancement of
6201-465: The RBMK and CANDU , are capable of operating with natural uranium as fuel). There are two commercial enrichment processes: gaseous diffusion and gas centrifugation . Both enrichment processes involve the use of uranium hexafluoride and produce enriched uranium oxide. Reprocessed uranium (RepU) undergoes a series of chemical and physical treatments to extract usable uranium from spent nuclear fuel. RepU
6318-409: The U isotope inhibits the runaway nuclear chain reaction that is responsible for the weapon's power. The critical mass for 85% highly enriched uranium is about 50 kilograms (110 lb), which at normal density would be a sphere about 17 centimetres (6.7 in) in diameter. Later U.S. nuclear weapons usually use plutonium-239 in the primary stage, but the jacket or tamper secondary stage, which
6435-479: The supercritical water reactor (SCWR) has sufficient heat capacity to allow adequate cooling with less water, making a fast-spectrum water-cooled reactor a practical possibility. The type of coolants, temperatures, and fast neutron spectrum puts the fuel cladding material (normally austenitic stainless or ferritic-martensitic steels) under extreme conditions. The understanding of the radiation damage, coolant interactions, stresses, and temperatures are necessary for
6552-407: The 1960s as more uranium reserves were found and new methods of uranium enrichment reduced fuel costs. Many types of breeder reactor are possible: A "breeder" is simply a nuclear reactor designed for very high neutron economy with an associated conversion rate higher than 1.0. In principle, almost any reactor design could be tweaked to become a breeder. For example, the light-water reactor ,
6669-576: The Netherlands, North Korea, Pakistan, Russia, the United Kingdom, and the United States. Belgium, Iran, Italy, and Spain hold an investment interest in the French Eurodif enrichment plant, with Iran's holding entitling it to 10% of the enriched uranium output. Countries that had enrichment programs in the past include Libya and South Africa, although Libya's facility was never operational. The Australian company Silex Systems has developed
6786-548: The Soviet BN-350 liquid-metal-cooled reactor. Theoretical models of breeders with liquid sodium coolant flowing through tubes inside fuel elements ("tube-in-shell" construction) suggest breeding ratios of at least 1.8 are possible on an industrial scale. The Soviet BR-1 test reactor achieved a breeding ratio of 2.5 under non-commercial conditions. Fission of the nuclear fuel in any reactor unavoidably produces neutron-absorbing fission products . The fertile material from
6903-635: The U.S. HEU Downblending Program, this HEU material, taken primarily from dismantled U.S. nuclear warheads, was recycled into low-enriched uranium (LEU) fuel, used by nuclear power plants to generate electricity. This innovative program not only facilitated the safe and secure elimination of excess weapons-grade uranium but also contributed to the sustainable operation of civilian nuclear power plants, reducing reliance on newly enriched uranium and promoting non-proliferation efforts globally The following countries are known to operate enrichment facilities: Argentina, Brazil, China, France, Germany, India, Iran, Japan,
7020-458: The actinide wastes as fuel and thus convert them to more fission products. After spent nuclear fuel is removed from a light water reactor, it undergoes a complex decay profile as each nuclide decays at a different rate. There is a large gap in the decay half-lives of fission products compared to transuranic isotopes. If the transuranics are left in the spent fuel, after 1,000 to 100,000 years the slow decay of these transuranics would generate most of
7137-406: The advantage that they are liquids at room temperature, which is convenient for experimental rigs but less important for pilot or full-scale power stations. Three of the proposed generation IV reactor types are FBRs: FBRs usually use a mixed oxide fuel core of up to 20% plutonium dioxide (PuO 2 ) and at least 80% uranium dioxide (UO 2 ). Another fuel option is metal alloys , typically
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#17327719632957254-468: The amount of NU required and the number of SWUs required during enrichment change in opposite directions, if NU is cheap and enrichment services are more expensive, then the operators will typically choose to allow more U to be left in the DU stream whereas if NU is more expensive and enrichment is less so, then they would choose the opposite. When converting uranium ( hexafluoride , hex for short) to metal, 0.3%
7371-428: The amount of plutonium available in spent reactor fuel, doubling time has become a less important metric in modern breeder-reactor design. " Burnup " is a measure of how much energy has been extracted from a given mass of heavy metal in fuel, often expressed (for power reactors) in terms of gigawatt-days per ton of heavy metal. Burnup is an important factor in determining the types and abundances of isotopes produced by
7488-414: The blanket region, and none in the reflector region. It operated at 236 MWt, generating 60 MWe, and ultimately produced over 2.1 billion kilowatt hours of electricity. After five years, the core was removed and found to contain nearly 1.4% more fissile material than when it was installed, demonstrating that breeding from thorium had occurred. A liquid fluoride thorium reactor is also planned as
7605-416: The blended LEU product. U is a neutron poison ; therefore the actual U concentration in the LEU product must be raised accordingly to compensate for the presence of U. While U also absorbs neutrons, it is a fertile material that is turned into fissile U upon neutron absorption . If U absorbs a neutron, the resulting short-lived U beta decays to Np , which
7722-497: The breeder-reactor fuel cycle posed an even greater proliferation concern because they would use PUREX to separate plutonium in a highly attractive isotopic form for use in nuclear weapons. Several countries are developing reprocessing methods that do not separate the plutonium from the other actinides. For instance, the non-water-based pyrometallurgical electrowinning process, when used to reprocess fuel from an integral fast reactor , leaves large amounts of radioactive actinides in
7839-489: The centrifugal forces is achieved by dilution of UF 6 with hydrogen or helium as a carrier gas achieving a much higher flow velocity for the gas than could be obtained using pure uranium hexafluoride. The Uranium Enrichment Corporation of South Africa (UCOR) developed and deployed the continuous Helikon vortex separation cascade for high production rate low-enrichment and the substantially different semi-batch Pelsakon low production rate high enrichment cascade both using
7956-424: The core are required to cool the reactor, the yield of neutrons and therefore breeding of Pu are strongly affected. Theoretical work has been done on reduced moderation water reactors , which may have a sufficiently fast spectrum to provide a breeding ratio slightly over 1. This would likely result in an unacceptable power derating and high costs in a liquid-water-cooled reactor, but the supercritical water coolant of
8073-809: The core at explosion time to contain a larger amount of fuel. This design strategy optimizes the explosive yield and performance of advanced nuclear weapons systems. The U is not said to be fissile but still is fissionable by fast neutrons (>2 MeV) such as the ones produced during D–T fusion . HEU is also used in fast neutron reactors , whose cores require about 20% or more of fissile material, as well as in naval reactors , where it often contains at least 50% U, but typically does not exceed 90%. These specialized reactor systems rely on highly enriched uranium for their unique operational requirements, including high neutron flux and precise control over reactor dynamics. The Fermi-1 commercial fast reactor prototype used HEU with 26.5% U. Significant quantities of HEU are used in
8190-493: The energy contained in uranium or thorium, decreasing fuel requirements by a factor of 100 compared to widely used once-through light water reactors, which extract less than 1% of the energy in the actinide metal (uranium or thorium) mined from the earth. The high fuel-efficiency of breeder reactors could greatly reduce concerns about fuel supply, energy used in mining, and storage of radioactive waste. With seawater uranium extraction (currently too expensive to be economical), there
8307-468: The enriched stream to contain 3.6% U (as compared to 0.7% in NU) while the depleted stream contains 0.2% to 0.3% U. In order to produce one kilogram of this LEU it would require approximately 8 kilograms of NU and 4.5 SWU if the DU stream was allowed to have 0.3% U. On the other hand, if the depleted stream had only 0.2% U, then it would require just 6.7 kilograms of NU, but nearly 5.7 SWU of enrichment. Because
8424-621: The enrichment process, its concentration increases but remains well below 1%. High concentrations of U are a byproduct from irradiation in a reactor and may be contained in the HEU, depending on its manufacturing history. U is produced primarily when U absorbs a neutron and does not fission. The production of U is thus unavoidable in any thermal neutron reactor with U fuel. HEU reprocessed from nuclear weapons material production reactors (with an U assay of approximately 50%) may contain U concentrations as high as 25%, resulting in concentrations of approximately 1.5% in
8541-442: The exact figure is classified. In August, 2011 Global Laser Enrichment, a subsidiary of GEH, applied to the U.S. Nuclear Regulatory Commission (NRC) for a permit to build a commercial plant. In September 2012, the NRC issued a license for GEH to build and operate a commercial SILEX enrichment plant, although the company had not yet decided whether the project would be profitable enough to begin construction, and despite concerns that
8658-426: The fertile material in the uranium fuel cycle has an atomic weight of 238. That mass difference means that thorium-232 requires six more neutron capture events per nucleus before the transuranic elements can be produced. In addition to this simple mass difference, the reactor gets two chances to fission the nuclei as the mass increases: First as the effective fuel nuclei U233, and as it absorbs two more neutrons, again as
8775-428: The following key assumptions: Some past anti-nuclear advocates have become pro-nuclear power as a clean source of electricity since breeder reactors effectively recycle most of their waste. This solves one of the most-important negative issues of nuclear power. In the documentary Pandora's Promise , a case is made for breeder reactors because they provide a real high-kW alternative to fossil fuel energy. According to
8892-474: The fuel nuclei U235. A reactor whose main purpose is to destroy actinides rather than increasing fissile fuel-stocks is sometimes known as a burner reactor . Both breeding and burning depend on good neutron economy, and many designs can do either. Breeding designs surround the core by a breeding blanket of fertile material. Waste burners surround the core with non-fertile wastes to be destroyed. Some designs add neutron reflectors or absorbers. One measure of
9009-573: The fuel such a 1 gigawatt reactor would need. Such self-contained breeders are currently envisioned as the final self-contained and self-supporting ultimate goal of nuclear reactor designers. The project was canceled in 1994 by United States Secretary of Energy Hazel O'Leary . The first fast reactor built and operated was the Los Alamos Plutonium Fast Reactor (" Clementine ") in Los Alamos, NM. Clementine
9126-447: The geometry of the fuel (which also contains uranium-238), arranged to attain sufficient fast neutron capture. The plutonium-239 (or the fissile uranium-235) fissile cross-section is much smaller in a fast spectrum than in a thermal spectrum, as is the ratio between the Pu/ U fission cross-section and the U absorption cross-section. This increases the concentration of Pu/ U needed to sustain
9243-408: The level of enrichment desired and upon the amount of U that ends up in the depleted uranium. However, unlike the number of SWUs required during enrichment, which increases with decreasing levels of U in the depleted stream, the amount of NU needed will decrease with decreasing levels of U that end up in the DU. For example, in the enrichment of LEU for use in a light water reactor it is typical for
9360-550: The license given to SILEX over nuclear proliferation concerns. It has also been claimed that Israel has a uranium enrichment program housed at the Negev Nuclear Research Center site near Dimona . During the Manhattan Project , weapons-grade highly enriched uranium was given the codename oralloy , a shortened version of Oak Ridge alloy, after the location of the plants where the uranium
9477-426: The long term. Germany, in contrast, abandoned the technology due to safety concerns. The SNR-300 fast breeder reactor was finished after 19 years despite cost overruns summing up to a total of € 3.6 billion, only to then be abandoned. The advanced heavy-water reactor is one of the few proposed large-scale uses of thorium. India is developing this technology, motivated by substantial thorium reserves; almost
9594-490: The main sequence of stellar evolution. No fission products have a half-life in the range of 100 a–210 ka ... ... nor beyond 15.7 Ma In broad terms, spent nuclear fuel has three main components. The first consists of fission products , the leftover fragments of fuel atoms after they have been split to release energy. Fission products come in dozens of elements and hundreds of isotopes, all of them lighter than uranium. The second main component of spent fuel
9711-416: The minor actinides (neptunium, americium, curium, etc.). Since breeder reactors on a closed fuel cycle would use nearly all of the isotopes of these actinides fed into them as fuel, their fuel requirements would be reduced by a factor of about 100. The volume of waste they generate would be reduced by a factor of about 100 as well. While there is a huge reduction in the volume of waste from a breeder reactor,
9828-435: The more mobile and troublesome radionuclides in deep geological repository disposal of nuclear waste. Reprocessed uranium often carries traces of other transuranic elements and fission products, necessitating careful monitoring and management during fuel fabrication and reactor operation. Low-enriched uranium (LEU) has a lower than 20% concentration of U; for instance, in commercial LWR, the most prevalent power reactors in
9945-403: The movie, one pound of uranium provides as much energy as 5,000 barrels of oil . The Soviet Union constructed a series of fast reactors, the first being mercury-cooled and fueled with plutonium metal, and the later plants sodium-cooled and fueled with plutonium oxide. BR-1 (1955) was 100W (thermal) was followed by BR-2 at 100 kW and then the 5 MW BR-5. BOR-60 (first criticality 1969)
10062-448: The non-fission capture reaction where U-235 absorbs a neutron but releases only a high energy gamma ray instead of undergoing fission. The physical behavior of the fission products is markedly different from that of the actinides. In particular, fission products do not undergo fission and therefore cannot be used as nuclear fuel. Indeed, because fission products are often neutron poisons (absorbing neutrons that could be used to sustain
10179-655: The nuclear fuel cycle. A major downblending undertaking called the Megatons to Megawatts Program converts ex-Soviet weapons-grade HEU to fuel for U.S. commercial power reactors. From 1995 through mid-2005, 250 tonnes of high-enriched uranium (enough for 10,000 warheads) was recycled into low-enriched uranium. The goal is to recycle 500 tonnes by 2013. The decommissioning programme of Russian nuclear warheads accounted for about 13% of total world requirement for enriched uranium leading up to 2008. This ambitious initiative not only addresses nuclear disarmament goals but also serves as
10296-604: The operation of the FBTR, a 500 MWe Prototype Fast Breeder Reactor (PFBR) is in advanced stage of construction at Kalpakkam. The reactor uses a plutonium - uranium mixed carbide fuel and liquid sodium as a coolant. The fuel is an indigenous mix of 70 percent plutonium carbide and 30 percent uranium carbide. Plutonium for the fuel is extracted from irradiated fuel in the Madras power reactors and reprocessed in Tarapur . Some of
10413-455: The past two decades, the most notable of these countries being Iran and North Korea, though all countries have had very limited success up to this point. Atomic vapor laser isotope separation employs specially tuned lasers to separate isotopes of uranium using selective ionization of hyperfine transitions . The technique uses lasers tuned to frequencies that ionize U atoms and no others. The positively charged U ions are then attracted to
10530-507: The power produced by commercial nuclear reactors comes from fission of plutonium generated within the fuel. Even with this level of plutonium consumption, light water reactors consume only part of the plutonium and minor actinides they produce, and nonfissile isotopes of plutonium build up, along with significant quantities of other minor actinides. Breeding fuel cycles attracted renewed interest because of their potential to reduce actinide wastes, particularly various isotopes of plutonium and
10647-494: The production of medical isotopes , for example molybdenum-99 for technetium-99m generators . The medical industry benefits from the unique properties of highly enriched uranium, which enable the efficient production of critical isotopes essential for diagnostic imaging and therapeutic applications Isotope separation is difficult because two isotopes of the same element have nearly identical chemical properties, and can only be separated gradually using small mass differences. ( U
10764-529: The protactinium remains in the reactor, small amounts of uranium-232 are also produced, which has the strong gamma emitter thallium-208 in its decay chain. Similar to uranium-fueled designs, the longer the fuel and fertile material remain in the reactor, the more of these undesirable elements build up. In the envisioned commercial thorium reactors , high levels of uranium-232 would be allowed to accumulate, leading to extremely high gamma-radiation doses from any uranium derived from thorium. These gamma rays complicate
10881-453: The radioactivity in that spent fuel. Thus, removing the transuranics from the waste eliminates much of the long-term radioactivity of spent nuclear fuel. Today's commercial light-water reactors do breed some new fissile material, mostly in the form of plutonium. Because commercial reactors were never designed as breeders, they do not convert enough uranium-238 into plutonium to replace the uranium-235 consumed. Nonetheless, at least one-third of
10998-672: The rare uranium-235 which is used in conventional reactors. These materials are called fertile materials since they can be bred into fuel by these breeder reactors. Breeder reactors achieve this because their neutron economy is high enough to create more fissile fuel than they use. These extra neutrons are absorbed by the fertile material that is loaded into the reactor along with fissile fuel. This irradiated fertile material in turn transmutes into fissile material which can undergo fission reactions . Breeders were at first found attractive because they made more complete use of uranium fuel than light-water reactors , but interest declined after
11115-418: The reactor fuel. More conventional water-based reprocessing systems include SANEX, UNEX, DIAMEX, COEX, and TRUEX, and proposals to combine PUREX with those and other co-processes. All these systems have moderately better proliferation resistance than PUREX, though their adoption rate is low. In the thorium cycle, thorium-232 breeds by converting first to protactinium-233, which then decays to uranium-233. If
11232-405: The reactor operated at 1 MW. In 1993, the reactor's power level was raised to 10.5 MW. In September 2002, fuel burn-up in the FBTR for the first time reached the 100,000 megawatt-days per metric ton uranium (MWd/MTU) mark. This is considered an important milestone in breeder reactor technology. On 7 March 2022 it attained the design power level of 40 MWt. Using the experience gained from
11349-501: The reactor. This process is an obvious chemical operation which is not required for normal operation of these reactor designs, but it could feasibly happen beyond the oversight of organizations such as the International Atomic Energy Agency (IAEA), and thus must be safeguarded against. Like many aspects of nuclear power, fast breeder reactors have been subject to much controversy over the years. In 2010
11466-508: The safe handling of a weapon and the design of its electronics; this explains why uranium-233 has never been pursued for weapons beyond proof-of-concept demonstrations. While the thorium cycle may be proliferation-resistant with regard to uranium-233 extraction from fuel (because of the presence of uranium-232), it poses a proliferation risk from an alternate route of uranium-233 extraction, which involves chemically extracting protactinium-233 and allowing it to decay to pure uranium-233 outside of
11583-408: The safe operation of any reactor core. All materials used to date in sodium-cooled fast reactors have known limits. Oxide dispersion-strengthened alloy steel is viewed as the long-term radiation resistant fuel-cladding material that can overcome the shortcomings of today's material choices. One design of fast neutron reactor, specifically conceived to address the waste disposal and plutonium issues,
11700-519: The salt carrier with heavier metal chlorides (e.g., KCl, RbCl, ZrCl 4 ). Several prototype FBRs have been built, ranging in electrical output from a few light bulbs' equivalent ( EBR-I , 1951) to over 1,000 MWe . As of 2006, the technology is not economically competitive to thermal reactor technology, but India , Japan, China, South Korea, and Russia are all committing substantial research funds to further development of fast breeder reactors, anticipating that rising uranium prices will change this in
11817-432: The same separation than the older gaseous diffusion process, which it has largely replaced and so is the current method of choice and is termed second generation . It has a separation factor per stage of 1.3 relative to gaseous diffusion of 1.005, which translates to about one-fiftieth of the energy requirements. Gas centrifuge techniques produce close to 100% of the world's enriched uranium. The cost per separative work unit
11934-535: The seventh nation to have the technology to build and operate a breeder reactor after United States , UK , France , Japan , Germany , and Russia . The reactor was designed to produce 40 MW of thermal power and 13.2 MW of electrical power. The initial nuclear fuel core used in the FBTR consisted of approximately 50 kg (110 lb) of weapons-grade plutonium . The FBTR has rarely operated at its designed capacity and had to be shut down between 1987 and 1989 due to technical problems. From 1989 to 1992,
12051-431: The site of the breeder reactor. Breeder reactors incorporating such technology would most likely be designed with breeding ratios very close to 1.00, so that after an initial loading of enriched uranium and/or plutonium fuel, the reactor would then be refueled only with small deliveries of natural uranium . A quantity of natural uranium equivalent to a block about the size of a milk crate delivered once per month would be all
12168-457: The technology could contribute to nuclear proliferation . The fear of nuclear proliferation arose in part due to laser separation technology requiring less than 25% of the space of typical separation techniques, as well as requiring only the energy that would power 12 typical houses, putting a laser separation plant that works by means of laser excitation well below the detection threshold of existing surveillance technologies. Due to these concerns
12285-486: The technology, GE Hitachi Nuclear Energy (GEH) signed a commercialization agreement with Silex Systems in 2006. GEH has since built a demonstration test loop and announced plans to build an initial commercial facility. Details of the process are classified and restricted by intergovernmental agreements between United States, Australia, and the commercial entities. SILEX has been projected to be an order of magnitude more efficient than existing production techniques but again,
12402-510: The term 'Calutron' applies to a multistage device arranged in a large oval around a powerful electromagnet. Electromagnetic isotope separation has been largely abandoned in favour of more effective methods. One chemical process has been demonstrated to pilot plant stage but not used for production. The French CHEMEX process exploited a very slight difference in the two isotopes' propensity to change valency in oxidation/reduction , using immiscible aqueous and organic phases. An ion-exchange process
12519-498: The transuranics in the final waste stream, this advantage would be greatly reduced. The FBR's fast neutrons can fission actinide nuclei with even numbers of both protons and neutrons. Such nuclei usually lack the low-speed "thermal neutron" resonances of fissile fuels used in LWRs. The thorium fuel cycle inherently produces lower levels of heavy actinides. The fertile material in the thorium fuel cycle has an atomic weight of 232, while
12636-624: The uranium is created from the transmutation of thorium bundles that are also placed in the core. This article about nuclear power and nuclear reactors for power generation is a stub . You can help Misplaced Pages by expanding it . This article about an Indian power station is a stub . You can help Misplaced Pages by expanding it . Breeder reactor A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be fueled with more-commonly available isotopes of uranium and thorium , such as uranium-238 and thorium-232 , as opposed to
12753-479: The waste. Some of these fission products could later be separated for industrial or medical uses and the rest sent to a waste repository. The IFR pyroprocessing system uses molten cadmium cathodes and electrorefiners to reprocess metallic fuel directly on-site at the reactor. Such systems co-mingle all the minor actinides with both uranium and plutonium. The systems are compact and self-contained, so that no plutonium-containing material needs to be transported away from
12870-557: The weapon's fissile core in a neutron reflector (which is standard on all nuclear explosives) can dramatically reduce the critical mass. Because the core was surrounded by a good neutron reflector, at explosion it comprised almost 2.5 critical masses. Neutron reflectors, compressing the fissile core via implosion, fusion boosting , and "tamping", which slows the expansion of the fissioning core with inertia, allow nuclear weapon designs that use less than what would be one bare-sphere critical mass at normal density. The presence of too much of
12987-444: The world, uranium is enriched to 3 to 5% U. Slightly enriched uranium ( SEU ) has a concentration of under 2% U. High-assay LEU (HALEU) is enriched between 5% and 20% and is called for in many small modular reactor (SMR) designs. Fresh LEU used in research reactors is usually enriched between 12% and 19.75% U; the latter concentration is used to replace HEU fuels when converting to LEU. Highly enriched uranium (HEU) has
13104-549: The world. Thermal diffusion uses the transfer of heat across a thin liquid or gas to accomplish isotope separation. The process exploits the fact that the lighter U gas molecules will diffuse toward a hot surface, and the heavier U gas molecules will diffuse toward a cold surface. The S-50 plant at Oak Ridge, Tennessee , was used during World War II to prepare feed material for the Electromagnetic isotope separation (EMIS) process, explained later in this article. It
13221-506: Was 60 MW, with construction started in 1965. India has been trying to develop fast breeder reactors for decades but suffered repeated delays. By December 2024 the Prototype Fast Breeder Reactor is due to be completed and commissioned. The program is intended to use fertile thorium-232 to breed fissile uranium-233. India is also pursuing thorium thermal breeder reactor technology. India's focus on thorium
13338-424: Was abandoned in favor of gaseous diffusion. The gas centrifuge process uses a large number of rotating cylinders in series and parallel formations. Each cylinder's rotation creates a strong centripetal force so that the heavier gas molecules containing U move tangentially toward the outside of the cylinder and the lighter gas molecules rich in U collect closer to the center. It requires much less energy to achieve
13455-535: Was developed by the Asahi Chemical Company in Japan that applies similar chemistry but effects separation on a proprietary resin ion-exchange column. Plasma separation process (PSP) describes a technique that makes use of superconducting magnets and plasma physics . In this process, the principle of ion cyclotron resonance is used to selectively energize the U isotope in a plasma containing
13572-424: Was fueled by Ga-stabilized delta-phase Pu and cooled with mercury. It contained a 'window' of Th-232 in anticipation of breeding experiments, but no reports were made available regarding this feature. Another proposed fast reactor is a fast molten salt reactor , in which the molten salt's moderating properties are insignificant. This is typically achieved by replacing the light metal fluorides (e.g. LiF, BeF 2 ) in
13689-477: Was the integral fast reactor (IFR, also known as an integral fast breeder reactor, although the original reactor was designed to not breed a net surplus of fissile material). To solve the waste disposal problem, the IFR had an on-site electrowinning fuel-reprocessing unit that recycled the uranium and all the transuranics (not just plutonium) via electroplating , leaving just short- half-life fission products in
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