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119-603: The Urenco Group is a British-German-Dutch nuclear fuel consortium operating several uranium enrichment plants in Germany, the Netherlands, United States, and United Kingdom. It supplies nuclear power stations in about 15 countries, and states that it had a 29% share of the global market for enrichment services in 2011. Urenco uses centrifuge enrichment technology. Urenco, headquartered in Stoke Poges , England,

238-417: 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

357-480: 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

476-773: 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

595-448: A company jointly owned with Areva . ETC provides enrichment-plant design services and gas-centrifuge technology for enrichment plants through its subsidiaries in the UK (Capenhurst), Germany (Gronau and Jülich), the Netherlands (Almelo), France (Tricastin) and the U.S. (Eunice, New Mexico). Urenco Netherlands BV has dismantled enrichment plant SP3, after the decommissioning of SP1 and SP2 in

714-481: A contract with Russia for the disposal of radioactive waste . In reality, these contracts do not relate to the disposal of waste, but to the sale of depleted uranium tails, which are re-enriched to natural uranium equivalent. As the enricher, Russia would be the owner of any radioactive waste that results from this process. In March 2009, there were protests about the largest-ever load of depleted uranium hexafluoride ( DU F 6 ) being transported from Germany to

833-541: A currently uneconomic prospect. A summary of the amounts of radioactive waste and management approaches for most developed countries are presented and reviewed periodically as part of a joint convention of the International Atomic Energy Agency (IAEA). A quantity of radioactive waste typically consists of a number of radionuclides , which are unstable isotopes of elements that undergo decay and thereby emit ionizing radiation , which

952-517: A developing organism such as a fetus is irradiated, it is possible a birth defect may be induced, but it is unlikely this defect will be in a gamete or a gamete-forming cell . The incidence of radiation-induced mutations in humans is small, as in most mammals, because of natural cellular-repair mechanisms, many just now coming to light. These mechanisms range from DNA, mRNA and protein repair, to internal lysosomic digestion of defective proteins, and even induced cell suicide—apoptosis Depending on

1071-520: A general rule, short-lived waste (mainly non-fuel materials from reactors) is buried in shallow repositories, while long-lived waste (from fuel and fuel reprocessing) is deposited in geological repository. Regulations in the United States do not define this category of waste; the term is used in Europe and elsewhere. ILW makes up 6% of all radioactive waste volume in the UK. High-level waste (HLW)

1190-492: A half-life that can stretch to as long as 24,000 years. The amount of HLW worldwide is increasing by about 12,000 tonnes per year. A 1000- megawatt nuclear power plant produces about 27 tonnes of spent nuclear fuel (unreprocessed) every year. For comparison, the amount of ash produced by coal power plants in the United States is estimated at 130,000,000 t per year and fly ash is estimated to release 100 times more radiation than an equivalent nuclear power plant. In 2010, it

1309-409: 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

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1428-525: 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

1547-500: 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

1666-438: A range of applications, such as oil well logging. Substances containing natural radioactivity are known as NORM (naturally occurring radioactive material). After human processing that exposes or concentrates this natural radioactivity (such as mining bringing coal to the surface or burning it to produce concentrated ash), it becomes technologically enhanced naturally occurring radioactive material (TENORM). Much of this waste

1785-511: A reactor. At that point, the fuel has to be replaced in the reactor with fresh fuel, even though there is still a substantial quantity of uranium-235 and plutonium present. In the United States, this used fuel is usually "stored", while in other countries such as Russia, the United Kingdom, France, Japan, and India, the fuel is reprocessed to remove the fission products, and the fuel can then be re-used. The fission products removed from

1904-405: A result of the processing or consumption of coal, oil, and gas, and some minerals, as discussed below. Waste from the front end of the nuclear fuel cycle is usually alpha-emitting waste from the extraction of uranium. It often contains radium and its decay products. Uranium dioxide (UO 2 ) concentrate from mining is a thousand or so times as radioactive as the granite used in buildings. It

2023-433: 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

2142-426: A similar way, the alpha emitting actinides and radium are considered very harmful as they tend to have long biological half-lives and their radiation has a high relative biological effectiveness , making it far more damaging to tissues per amount of energy deposited. Because of such differences, the rules determining biological injury differ widely according to the radioisotope, time of exposure, and sometimes also

2261-446: A stable state but rather to radioactive decay products within a decay chain before ultimately reaching a stable state. Exposure to radioactive waste may cause health impacts due to ionizing radiation exposure. In humans, a dose of 1 sievert carries a 5.5% risk of developing cancer, and regulatory agencies assume the risk is linearly proportional to dose even for low doses. Ionizing radiation can cause deletions in chromosomes. If

2380-505: A storage area, and the enrichment methods required have high capital costs. Pu-239 decays to U-235 which is suitable for weapons and which has a very long half-life (roughly 10 years). Thus plutonium may decay and leave uranium-235. However, modern reactors are only moderately enriched with U-235 relative to U-238, so the U-238 continues to serve as a denaturation agent for any U-235 produced by plutonium decay. One solution to this problem

2499-505: Is alpha particle -emitting matter from the decay chains of uranium and thorium. The main source of radiation in the human body is potassium -40 ( K ), typically 17 milligrams in the body at a time and 0.4 milligrams/day intake. Most rocks, especially granite , have a low level of radioactivity due to the potassium-40, thorium and uranium contained. Usually ranging from 1 millisievert (mSv) to 13 mSv annually depending on location, average radiation exposure from natural radioisotopes

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2618-434: Is reactor-grade plutonium . In addition to plutonium-239 , which is highly suitable for building nuclear weapons, it contains large amounts of undesirable contaminants: plutonium-240 , plutonium-241 , and plutonium-238 . These isotopes are extremely difficult to separate, and more cost-effective ways of obtaining fissile material exist (e.g., uranium enrichment or dedicated plutonium production reactors). High-level waste

2737-487: Is 2.0 mSv per person a year worldwide. This makes up the majority of typical total dosage (with mean annual exposure from other sources amounting to 0.6 mSv from medical tests averaged over the whole populace, 0.4 mSv from cosmic rays , 0.005 mSv from the legacy of past atmospheric nuclear testing, 0.005 mSv occupational exposure, 0.002 mSv from the Chernobyl disaster , and 0.0002 mSv from

2856-503: Is a fertile material that can undergo a neutron capture reaction and two beta minus decays, resulting in the production of fissile U-233 . The SNF of a cycle with thorium will contain U-233. Its radioactive decay will strongly influence the long-term activity curve of the SNF for around a million years. A comparison of the activity associated to U-233 for three different SNF types can be seen in

2975-406: Is a fissile material used in nuclear bombs, plus some material with much higher specific activities, such as Pu-238 or Po. In the past the neutron trigger for an atomic bomb tended to be beryllium and a high activity alpha emitter such as polonium ; an alternative to polonium is Pu-238 . For reasons of national security, details of the design of modern nuclear bombs are normally not released to

3094-424: Is a gamma emitter (increasing external-exposure to workers) and is an alpha emitter which can cause the generation of heat . The plutonium could be separated from the americium by several different processes; these would include pyrochemical processes and aqueous/organic solvent extraction . A truncated PUREX type extraction process would be one possible method of making the separation. Naturally occurring uranium

3213-410: 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

3332-520: 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

3451-534: 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

3570-440: 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

3689-404: 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

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3808-437: 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

3927-408: 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

4046-640: 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

4165-514: 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

4284-615: Is full of highly radioactive fission products , most of which are relatively short-lived. This is a concern since if the waste is stored, perhaps in deep geological storage, over many years the fission products decay, decreasing the radioactivity of the waste and making the plutonium easier to access. The undesirable contaminant Pu-240 decays faster than the Pu-239, and thus the quality of the bomb material increases with time (although its quantity decreases during that time as well). Thus, some have argued, as time passes, these deep storage areas have

4403-457: 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

4522-516: Is generated from hospitals and industry, as well as the nuclear fuel cycle . Low-level wastes include paper, rags, tools, clothing, filters, and other materials which contain small amounts of mostly short-lived radioactivity. Materials that originate from any region of an Active Area are commonly designated as LLW as a precautionary measure even if there is only a remote possibility of being contaminated with radioactive materials. Such LLW typically exhibits no higher radioactivity than one would expect from

4641-477: Is harmful to humans and the environment. Different isotopes emit different types and levels of radiation, which last for different periods of time. The radioactivity of all radioactive waste weakens with time. All radionuclides contained in the waste have a half-life —the time it takes for half of the atoms to decay into another nuclide . Eventually, all radioactive waste decays into non-radioactive elements (i.e., stable nuclides ). Since radioactive decay follows

4760-560: Is highly radioactive and hot due to decay heat, thus requiring cooling and shielding. In nuclear reprocessing plants, about 96% of spent nuclear fuel is recycled back into uranium-based and mixed-oxide (MOX) fuels . The residual 4% is minor actinides and fission products , the latter of which are a mixture of stable and quickly decaying (most likely already having decayed in the spent fuel pool ) elements, medium lived fission products such as strontium-90 and caesium-137 and finally seven long-lived fission products with half lives in

4879-518: 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

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4998-429: Is important to distinguish the processing of uranium to make fuel from the reprocessing of used fuel. Used fuel contains the highly radioactive products of fission (see high-level waste below). Many of these are neutron absorbers, called neutron poisons in this context. These eventually build up to a level where they absorb so many neutrons that the chain reaction stops, even with the control rods completely removed from

5117-477: 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

5236-435: 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

5355-399: 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

5474-469: 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

5593-597: Is not fissile because it contains 99.3% of U-238 and only 0.7% of U-235. Due to historic activities typically related to the radium industry, uranium mining, and military programs, numerous sites contain or are contaminated with radioactivity. In the United States alone, the Department of Energy (DOE) states there are "millions of gallons of radioactive waste" as well as "thousands of tons of spent nuclear fuel and material" and also "huge quantities of contaminated soil and water." Despite copious quantities of waste, in 2007,

5712-606: 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

5831-690: 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

5950-512: Is owned one third by the UK government, one third by the Dutch government, and the final third equally by two major German utilities, E.ON and RWE . Urenco is owned in three equal parts by Ultra-Centrifuge Nederland NV (owned by the Government of the Netherlands ), Uranit GmbH (owned equally by German energy companies E.ON and RWE ) and Enrichment Holdings Ltd (owned by the Government of

6069-423: Is produced by nuclear reactors and the reprocessing of nuclear fuel. The exact definition of HLW differs internationally. After a nuclear fuel rod serves one fuel cycle and is removed from the core, it is considered HLW. Spent fuel rods contain mostly uranium with fission products and transuranic elements generated in the reactor core . Spent fuel is highly radioactive and often hot. HLW accounts for over 95% of

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6188-528: Is refined from yellowcake (U 3 O 8 ), then converted to uranium hexafluoride gas (UF 6 ). As a gas, it undergoes enrichment to increase the U-235 content from 0.7% to about 4.4% (LEU). It is then turned into a hard ceramic oxide (UO 2 ) for assembly as reactor fuel elements. The main by-product of enrichment is depleted uranium (DU), principally the U-238 isotope, with a U-235 content of ~0.3%. It

6307-432: Is stored, either as UF 6 or as U 3 O 8 . Some is used in applications where its extremely high density makes it valuable such as anti-tank shells , and on at least one occasion even a sailboat keel . It is also used with plutonium for making mixed oxide fuel (MOX) and to dilute, or downblend , highly enriched uranium from weapons stockpiles which is now being redirected to become reactor fuel. The back-end of

6426-466: 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

6545-426: Is to recycle the plutonium and use it as a fuel e.g. in fast reactors . In pyrometallurgical fast reactors , the separated plutonium and uranium are contaminated by actinides and cannot be used for nuclear weapons. Waste from nuclear weapons decommissioning is unlikely to contain much beta or gamma activity other than tritium and americium . It is more likely to contain alpha-emitting actinides such as Pu-239 which

6664-487: 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

6783-616: 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

6902-556: 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

7021-472: 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

7140-473: The PUREX -process disposes of them as waste together with the fission products. The waste is subsequently converted into a glass-like ceramic for storage in a deep geological repository . The time radioactive waste must be stored depends on the type of waste and radioactive isotopes it contains. Short-term approaches to radioactive waste storage have been segregation and storage on the surface or near-surface of

7259-780: The Project-706 uranium enrichment programme, launched by Munir Ahmad Khan under Zulfikar Ali Bhutto , Pakistani Prime Minister at that time. Later, he took over the project, and established a facility that produced highly enriched uranium (HEU). Within a short span of time he established a highly advanced uranium enrichment facility near Islamabad . In May 1985, the United Nations Council for Namibia (UNCN) decided to take legal action against Urenco for breaching UNCN Decree No 1, which prohibited any exploitation of Namibia's natural resources under apartheid South Africa , because Urenco had been importing uranium ore from

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7378-465: 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

7497-607: The Rössing mine in Namibia. The case was expected to be ready by the end of 1985 but was delayed because Urenco argued that, despite having enriched uranium of Namibian origin since 1980, it was impossible to tell where specific consignments came from. When the case finally reached court in July 1986, the Dutch government took Urenco's line, claiming not to have known where the uranium had been mined. According to Greenpeace , Urenco has

7616-493: The Siberian town Seversk . 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

7735-409: 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

7854-533: The 1980s and 1990s. Information about decommissioning cost calculations for Urenco facilities is not accessible. In the 1970s, Abdul Qadeer Khan , who worked for a subcontractor of Urenco in Almelo , brought the drawings of the centrifuges operated by Urenco to Pakistan by skipping the Urenco administration and the Dutch government. Those blueprints were stolen from the Urenco administration. In early 1974, Khan joined

7973-715: The DOE has successfully completed cleanup, or at least closure, of several sites. Radioactive medical waste tends to contain beta particle and gamma ray emitters. It can be divided into two main classes. In diagnostic nuclear medicine a number of short-lived gamma emitters such as technetium-99m are used. Many of these can be disposed of by leaving it to decay for a short time before disposal as normal waste. Other isotopes used in medicine, with half-lives in parentheses, include: Industrial source waste can contain alpha, beta , neutron or gamma emitters. Gamma emitters are used in radiography while neutron emitting sources are used in

8092-569: The DOE stated a goal of cleaning all presently contaminated sites successfully by 2025. The Fernald , Ohio site for example had "31 million pounds of uranium product", "2.5 billion pounds of waste", "2.75 million cubic yards of contaminated soil and debris", and a "223 acre portion of the underlying Great Miami Aquifer had uranium levels above drinking standards." The United States has at least 108 sites designated as areas that are contaminated and unusable, sometimes many thousands of acres. The DOE wishes to clean or mitigate many or all by 2025, using

8211-545: The MOX fuel results in a lower activity in region 3 of the figure at the bottom right, whereas for RGPu and WGPu the curve is maintained higher due to the presence of U-233 that has not fully decayed. Nuclear reprocessing can remove the actinides from the spent fuel so they can be used or destroyed (see Long-lived fission product § Actinides ). Since uranium and plutonium are nuclear weapons materials, there are proliferation concerns. Ordinarily (in spent nuclear fuel), plutonium

8330-516: 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

8449-408: The Pu-239; due to the relatively long half-life of these Pu isotopes, these wastes from radioactive decay of bomb core material would be very small, and in any case, far less dangerous (even in terms of simple radioactivity) than the Pu-239 itself. The beta decay of Pu-241 forms Am-241 ; the in-growth of americium is likely to be a greater problem than the decay of Pu-239 and Pu-240 as the americium

8568-1121: The Radioactive Waste Safety Standards (RADWASS), also plays a significant role. The proportion of various types of waste generated in the UK: Uranium tailings are waste by-product materials left over from the rough processing of uranium-bearing ore . They are not significantly radioactive. Mill tailings are sometimes referred to as 11(e)2 wastes , from the section of the US Atomic Energy Act of 1946 that defines them. Uranium mill tailings typically also contain chemically hazardous heavy metal such as lead and arsenic . Vast mounds of uranium mill tailings are left at many old mining sites, especially in Colorado , New Mexico , and Utah . Although mill tailings are not very radioactive, they have long half-lives. Mill tailings often contain radium, thorium and trace amounts of uranium. Low-level waste (LLW)

8687-635: 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,

8806-541: The United Kingdom and managed by UK Government Investments ). The company was set up in 1971, pursuant to the Treaty of Almelo (named after the community in the Netherlands where the company originated), which restricts the sale of ownership stakes. Urenco Deutschland, Urenco UK, and Urenco Nederland are 100% subsidiaries of Urenco Enrichment Company. They operate enrichment plants at Gronau , Westphalia , Germany, at Capenhurst , England, and at Almelo , Netherlands. In

8925-649: The United States, where Urenco is represented by its marketing subsidiary Urenco, Inc., the Urenco USA facility became operational in spring 2010. Called the National Enrichment Facility , it is located 5 miles (8.0 km) east of Eunice, New Mexico , and is operated by Urenco's subsidiary Louisiana Energy Services (LES). Urenco also owns a 50% interest in Enrichment Technology Company  [ nl ] (ETC),

9044-468: 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%

9163-639: The ash content of 'dirty' coals. The more active ash minerals become concentrated in the fly ash precisely because they do not burn well. The radioactivity of fly ash is about the same as black shale and is less than phosphate rocks, but is more of a concern because a small amount of the fly ash ends up in the atmosphere where it can be inhaled. According to U.S. National Council on Radiation Protection and Measurements (NCRP) reports, population exposure from 1000-MWe power plants amounts to 490 person-rem/year for coal power plants, 100 times as great as nuclear power plants (4.8 person-rem/year). The exposure from

9282-448: The back end of the fuel cycle is especially relevant when designing a complete waste management plan for SNF. When looking at long-term radioactive decay, the actinides in the SNF have a significant influence due to their characteristically long half-lives. Depending on what a nuclear reactor is fueled with, the actinide composition in the SNF will be different. An example of this effect is the use of nuclear fuels with thorium . Th-232

9401-416: 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

9520-489: 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

9639-452: The complete nuclear fuel cycle from mining to waste disposal is 136 person-rem/year; the corresponding value for coal use from mining to waste disposal is "probably unknown". Residues from the oil and gas industry often contain radium and its decay products. The sulfate scale from an oil well can be radium rich, while the water, oil, and gas from a well often contain radon . The radon decays to form solid radioisotopes which form coatings on

9758-809: 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

9877-425: The decay mode and the pharmacokinetics of an element (how the body processes it and how quickly), the threat due to exposure to a given activity of a radioisotope will differ. For instance, iodine-131 is a short-lived beta and gamma emitter, but because it concentrates in the thyroid gland, it is more able to cause injury than caesium -137 which, being water soluble , is rapidly excreted through urine. In

9996-607: The earth. Burial in a deep geological repository is a favored solution for long-term storage of high-level waste, while re-use and transmutation are favored solutions for reducing the HLW inventory. Boundaries to recycling of spent nuclear fuel are regulatory and economic as well as the issue of radioactive contamination if chemical separation processes cannot achieve a very high purity. Furthermore, elements may be present in both useful and troublesome isotopes, which would require costly and energy intensive isotope separation for their use –

10115-468: 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

10234-621: 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

10353-442: 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

10472-411: The figure on the top right. The burnt fuels are thorium with reactor-grade plutonium (RGPu), thorium with weapons-grade plutonium (WGPu), and Mixed oxide fuel (MOX, no thorium). For RGPu and WGPu, the initial amount of U-233 and its decay for around a million years can be seen. This has an effect on the total activity curve of the three fuel types. The initial absence of U-233 and its daughter products in

10591-567: The fuel are a concentrated form of high-level waste as are the chemicals used in the process. While most countries reprocess the fuel carrying out single plutonium cycles, India is planning multiple plutonium recycling schemes and Russia pursues closed cycle. The use of different fuels in nuclear reactors results in different spent nuclear fuel (SNF) composition, with varying activity curves. The most abundant material being U-238 with other uranium isotopes, other actinides, fission products and activation products. Long-lived radioactive waste from

10710-416: The half-life rule, the rate of decay is inversely proportional to the duration of decay. In other words, the radiation from a long-lived isotope like iodine-129 will be much less intense than that of a short-lived isotope like iodine-131 . The two tables show some of the major radioisotopes, their half-lives, and their radiation yield as a proportion of the yield of fission of uranium-235. The energy and

10829-411: The hundreds of thousands to millions of years. The minor actinides meanwhile are heavy elements other than uranium and plutonium which are created by neutron capture . Their half lives range from years to millions of years and as alpha emitters they are particularly radiotoxic. While there are proposed – and to a much lesser extent current – uses of all those elements, commercial scale reprocessing using

10948-412: The inside of pipework. In an oil processing plant, the area of the plant where propane is processed is often one of the more contaminated areas of the plant as radon has a similar boiling point to propane. Radioactive elements are an industrial problem in some oil wells where workers operating in direct contact with the crude oil and brine can be exposed to doses having negative health effects. Due to

11067-408: 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

11186-550: 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

11305-435: 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

11424-565: The nature of the chemical compound which contains the radioisotope. No fission products have a half-life in the range of 100 a–210 ka ... ... nor beyond 15.7 Ma Radioactive waste comes from a number of sources. In countries with nuclear power plants, nuclear armament, or nuclear fuel treatment plants, the majority of waste originates from the nuclear fuel cycle and nuclear weapons reprocessing. Other sources include medical and industrial wastes, as well as naturally occurring radioactive materials (NORM) that can be concentrated as

11543-891: The north of Scotland is the Dounreay site which is prepared to withstand a 4m tsunami. [1] Some high-activity LLW requires shielding during handling and transport but most LLW is suitable for shallow land burial. To reduce its volume, it is often compacted or incinerated before disposal. Low-level waste is divided into four classes: class A , class B , class C , and Greater Than Class C ( GTCC ). Intermediate-level waste (ILW) contains higher amounts of radioactivity compared to low-level waste. It generally requires shielding, but not cooling. Intermediate-level wastes includes resins , chemical sludge and metal nuclear fuel cladding, as well as contaminated materials from reactor decommissioning. It may be solidified in concrete or bitumen or mixed with silica sand and vitrified for disposal. As

11662-577: The nuclear fuel cycle). TENORM is not regulated as restrictively as nuclear reactor waste, though there are no significant differences in the radiological risks of these materials. Coal contains a small amount of radioactive uranium, barium, thorium, and potassium, but, in the case of pure coal, this is significantly less than the average concentration of those elements in the Earth's crust . The surrounding strata, if shale or mudstone, often contain slightly more than average and this may also be reflected in

11781-491: The nuclear fuel cycle, mostly spent fuel rods , contains fission products that emit beta and gamma radiation, and actinides that emit alpha particles , such as uranium-234 (half-life 245 thousand years), neptunium-237 (2.144 million years), plutonium-238 (87.7 years) and americium-241 (432 years), and even sometimes some neutron emitters such as californium (half-life of 898 years for californium-251). These isotopes are formed in nuclear reactors . It

11900-655: 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

12019-440: The open literature. Some designs might contain a radioisotope thermoelectric generator using Pu-238 to provide a long-lasting source of electrical power for the electronics in the device. It is likely that the fissile material of an old nuclear bomb, which is due for refitting, will contain decay products of the plutonium isotopes used in it. These are likely to include U-236 from Pu-240 impurities plus some U-235 from decay of

12138-455: 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

12257-402: The potential to become "plutonium mines", from which material for nuclear weapons can be acquired with relatively little difficulty. Critics of the latter idea have pointed out the difficulty of recovering useful material from sealed deep storage areas makes other methods preferable. Specifically, high radioactivity and heat (80 °C in surrounding rock) greatly increase the difficulty of mining

12376-494: 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

12495-477: The recently developed method of geomelting , however the task can be difficult and it acknowledges that some may never be completely remediated. In just one of these 108 larger designations, Oak Ridge National Laboratory (ORNL), there were for example at least "167 known contaminant release sites" in one of the three subdivisions of the 37,000-acre (150 km ) site. Some of the U.S. sites were smaller in nature, however, cleanup issues were simpler to address, and

12614-588: The relatively high concentration of these elements in the brine, its disposal is also a technological challenge. Since the 1980s, in the United States, the brine is however exempt from the dangerous waste regulations and can be disposed of regardless of radioactive or toxic substances content. Due to natural occurrence of radioactive elements such as thorium and radium in rare-earth ore , mining operations also result in production of waste and mineral deposits that are slightly radioactive. Classification of radioactive waste varies by country. The IAEA, which publishes

12733-457: The same material disposed of in a non-active area, such as a normal office block. Example LLW includes wiping rags, mops, medical tubes, laboratory animal carcasses, and more. LLW makes up 94% of all radioactive waste volume in the UK. Most of it is disposed of in Cumbria , first in landfill style trenches, and now using grouted metal containers that are stacked in concrete vaults. A new site in

12852-432: 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

12971-457: 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

13090-486: 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,

13209-510: 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

13328-637: The total radioactivity produced in the process of nuclear electricity generation but it contributes to less than 1% of volume of all radioactive waste produced in the UK. Overall, the 60-year-long nuclear program in the UK up until 2019 produced 2150 m of HLW. The radioactive waste from spent fuel rods consists primarily of cesium-137 and strontium-90, but it may also include plutonium, which can be considered transuranic waste. The half-lives of these radioactive elements can differ quite extremely. Some elements, such as cesium-137 and strontium-90 have half-lives of approximately 30 years. Meanwhile, plutonium has

13447-403: The type of the ionizing radiation emitted by a radioactive substance are also important factors in determining its threat to humans. The chemical properties of the radioactive element will determine how mobile the substance is and how likely it is to spread into the environment and contaminate humans. This is further complicated by the fact that many radioisotopes do not decay immediately to

13566-557: 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

13685-444: 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

13804-549: 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

13923-424: 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

14042-535: 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

14161-772: Was enriched. This covert terminology underscores the secrecy and sensitivity surrounding the production of highly enriched uranium during World War II, highlighting the strategic importance of the Manhattan Project and its role in the development of nuclear weapons. The term oralloy is still occasionally used to refer to enriched uranium. Radioactive waste Radioactive waste is broadly classified into 3 categories: low-level waste (LLW), such as paper, rags, tools, clothing, which contain small amounts of mostly short-lived radioactivity; intermediate-level waste (ILW), which contains higher amounts of radioactivity and requires some shielding; and high-level waste (HLW), which

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