74-560: The Thermal Oxide Reprocessing Plant , or THORP , is a nuclear fuel reprocessing plant at Sellafield in Cumbria , England. THORP is owned by the Nuclear Decommissioning Authority and operated by Sellafield Ltd , the site licensee. Spent nuclear fuel from nuclear reactors was reprocessed to separate the 96% uranium and the 1% plutonium from the 3% radioactive wastes, which are treated and stored at
148-515: A UREX ( UR anium EX traction) process which could be used to save space inside high level nuclear waste disposal sites, such as the Yucca Mountain nuclear waste repository , by removing the uranium which makes up the vast majority of the mass and volume of used fuel and recycling it as reprocessed uranium . The UREX process is a PUREX process which has been modified to prevent the plutonium from being extracted. This can be done by adding
222-472: A byproduct. Because this could allow for weapons grade nuclear material , nuclear reprocessing is a concern for nuclear proliferation and is thus tightly regulated. Relatively high cost is associated with spent fuel reprocessing compared to the once-through fuel cycle, but fuel use can be increased and waste volumes decreased. Nuclear fuel reprocessing is performed routinely in Europe, Russia, and Japan. In
296-838: A chamber full of fluorine. This is known as flame fluorination; the heat produced helps the reaction proceed. Most of the uranium , which makes up the bulk of the fuel, is converted to uranium hexafluoride , the form of uranium used in uranium enrichment , which has a very low boiling point. Technetium , the main long-lived fission product , is also efficiently converted to its volatile hexafluoride. A few other elements also form similarly volatile hexafluorides, pentafluorides, or heptafluorides. The volatile fluorides can be separated from excess fluorine by condensation, then separated from each other by fractional distillation or selective reduction . Uranium hexafluoride and technetium hexafluoride have very similar boiling points and vapor pressures, which makes complete separation more difficult. Many of
370-483: A highly radioactive solution, which had started in July 2004. British Nuclear Group's board of inquiry determined that a design error led to the leak, while a complacent culture at the plant delayed detection for nine months. Operations staff did not discover the leak until safeguards staff reported major fluid accountancy discrepancies. Altogether 83 cubic metres (82,966 litres ) of hot nitric acid solution leaked from
444-476: A method for removing zirconium fuel cladding, instead of mechanical decladding. Chlorides are likely to be easier than fluorides to later convert back to other compounds, such as oxides. Chlorides remaining after volatilization may also be separated by solubility in water. Chlorides of alkaline elements like americium , curium , lanthanides , strontium , caesium are more soluble than those of uranium , neptunium , plutonium , and zirconium . To determine
518-526: A neutron driven nuclear reaction. To date the extraction system for the SANEX process has not been defined, but currently several different research groups are working towards a process. For instance the French CEA is working on a bis-triazinyl pyridine (BTP) based process. Other systems such as the dithiophosphinic acids are being worked on by some other workers. The UN iversal EX traction process
592-522: A plutonium reductant before the first metal extraction step. In the UREX process, ~99.9% of the uranium and >95% of technetium are separated from each other and the other fission products and actinides . The key is the addition of acetohydroxamic acid (AHA) to the extraction and scrub sections of the process. The addition of AHA greatly diminishes the extractability of plutonium and neptunium , providing somewhat greater proliferation resistance than with
666-514: A radioactive beta-emitter with a half-life of 10.7 years. The Radiological Protection Institute of Ireland (RPII) commenced 24-hour atmospheric monitoring for krypton-85 in 1993, prior to the plant's commissioning. The cooled oxide fuel is chopped up in the Shear Cell and the fuel dissolved in nitric acid. It is chemically conditioned before passing to the chemical separation plant. Pulsed columns (designated HA/HS) are used to initially separate
740-477: A small fractured feedpipe, which was discovered when a remote camera was sent in to examine THORP's Feed Clarification Cell on 19 April 2005. All the fluids collected under gravity into the secondary containment , which is a stainless steel tub embedded in 2-metre thick reinforced concrete , capable of holding 250 cubic metres of fluids. The solution from the spill was estimated to contain 20 metric tons of uranium and 160 kilograms of plutonium. The leaked solution
814-983: A smaller plant at West Valley Reprocessing Plant which closed by 1972 because of its inability to meet new regulatory requirements. Reprocessing of civilian fuel has long been employed at the COGEMA La Hague site in France, the Sellafield site in the United Kingdom, the Mayak Chemical Combine in Russia, and at sites such as the Tokai plant in Japan, the Tarapur plant in India, and briefly at
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#1732779959500888-446: A solid aluminium cathode. As an alternative to electrowinning, the wanted metal can be isolated by using a molten alloy of an electropositive metal and a less reactive metal. Since the majority of the long term radioactivity , and volume, of spent fuel comes from actinides, removing the actinides produces waste that is more compact, and not nearly as dangerous over the long term. The radioactivity of this waste will then drop to
962-482: A vacuum. If a carrier salt like lithium fluoride or sodium fluoride is being used as a solvent, high-temperature distillation is a way to separate the carrier salt for reuse. Molten salt reactor designs carry out fluoride volatility reprocessing continuously or at frequent intervals. The goal is to return actinides to the molten fuel mixture for eventual fission, while removing fission products that are neutron poisons , or that can be more securely stored outside
1036-501: Is a generic term for high-temperature methods. Solvents are molten salts (e.g. LiCl + KCl or LiF + CaF 2 ) and molten metals (e.g. cadmium, bismuth, magnesium) rather than water and organic compounds. Electrorefining , distillation , and solvent-solvent extraction are common steps. These processes are not currently in significant use worldwide, but they have been pioneered at Argonne National Laboratory with current research also taking place at CRIEPI in Japan,
1110-459: Is an obsolete process that adds significant unnecessary material to the final radioactive waste. The bismuth phosphate process has been replaced by solvent extraction processes. The bismuth phosphate process was designed to extract plutonium from aluminium-clad nuclear fuel rods , containing uranium. The fuel was decladded by boiling it in caustic soda . After decladding, the uranium metal was dissolved in nitric acid . The plutonium at this point
1184-424: Is applied, causing the uranium metal (or sometimes oxide, depending on the spent fuel) to plate out on a solid metal cathode while the other actinides (and the rare earths) can be absorbed into a liquid cadmium cathode. Many of the fission products (such as caesium , zirconium and strontium ) remain in the salt. As alternatives to the molten cadmium electrode it is possible to use a molten bismuth cathode, or
1258-461: Is decreased. Most of the plutonium and some of the uranium will initially remain in ash which drops to the bottom of the flame fluorinator. The plutonium-uranium ratio in the ash may even approximate the composition needed for fast neutron reactor fuel. Further fluorination of the ash can remove all the uranium, neptunium , and plutonium as volatile fluorides; however, some other minor actinides may not form volatile fluorides and instead remain with
1332-495: Is expected to occur between 2075 and 2095. The estimated cost of decommissioning is forecast as £4 billion at 2018 prices. The chemical flowsheet for THORP is designed to add less non-volatile matter to the first cycle PUREX raffinate . One way in which this is done is by avoiding the use of ferrous compounds as plutonium reducing agents. In this plant the reduction is done using either hydrazine or HAN ( hydroxylamine nitrate ). The plant releases gaseous emissions of krypton-85,
1406-467: Is free from uranium and contains recovered transuranics in an inert matrix such as metallic zirconium . In the PYRO-B processing of such fuel, an electrorefining step is used to separate the residual transuranic elements from the fission products and recycle the transuranics to the reactor for fissioning. Newly generated technetium and iodine are extracted for incorporation into transmutation targets, and
1480-466: Is in the +4 oxidation state. It was then precipitated out of the solution by the addition of bismuth nitrate and phosphoric acid to form the bismuth phosphate. The plutonium was coprecipitated with this. The supernatant liquid (containing many of the fission products ) was separated from the solid. The precipitate was then dissolved in nitric acid before the addition of an oxidant (such as potassium permanganate ) to produce PuO 2 . The plutonium
1554-427: Is reduced to the +3 oxidation state, which is insoluble in the solvent phase so ends up in the aqueous phase exiting the 1BX column. The 1BXX mixer/settler completes the removal of Pu from the solvent phase. The 1BS column removes any remaining Uranium from the aqueous phase by the use of fresh solvent. Pulsed columns then purify the plutonium, removing the troublesome fission products that remain. A mixer/settler (1C)
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#17327799595001628-456: Is substantially different from the usual uranium or mixed uranium-plutonium oxides (MOX) that most current reactors were designed to use. Another pyrochemical process, the PYRO-B process, has been developed for the processing and recycling of fuel from a transmuter reactor ( a fast breeder reactor designed to convert transuranic nuclear waste into fission products ). A typical transmuter fuel
1702-517: Is that by lowering the alpha activity of the waste, the majority of the waste can then be disposed of with greater ease. In common with PUREX this process operates by a solvation mechanism. As an alternative to TRUEX, an extraction process using a malondiamide has been devised. The DIAMEX ( DIAM ide EX traction) process has the advantage of avoiding the formation of organic waste which contains elements other than carbon , hydrogen , nitrogen , and oxygen . Such an organic waste can be burned without
1776-475: Is used to transfer (washes) the uranium across to the aqueous phase ready for the next stage. Uranium purification is achieved using three mixer settlers (UP1 - UP3) similar to those in use on the existing Magnox reprocessing plant. Evaporation of the two product streams then occurs before further processing is undertaken. Uranium is converted to UO 3 powder while the plutonium is converted to PuO 2 powder and sent to storage. Pulsed columns were chosen to avoid
1850-450: Is very wide, but all agreed that under then-current economic conditions the reprocessing-recycle option is the more costly one. While the uranium market - particularly its short term fluctuations - has only a minor impact on the cost of electricity from nuclear power, long-term trends in the uranium market do significantly affect the economics of nuclear reprocessing. If uranium prices were to rise and remain consistently high, "stretching
1924-474: The International System of Units (SI). Its symbol is m . It is the volume of a cube with edges one metre in length. An alternative name, which allowed a different usage with metric prefixes , was the stère , still sometimes used for dry measure (for instance, in reference to wood ). Another alternative name, no longer widely used, was the kilolitre . A cubic metre of pure water at
1998-567: The West Valley Reprocessing Plant in the United States. In October 1976, concern of nuclear weapons proliferation (especially after India demonstrated nuclear weapons capabilities using reprocessing technology) led President Gerald Ford to issue a Presidential directive to indefinitely suspend the commercial reprocessing and recycling of plutonium in the U.S. On 7 April 1977, President Jimmy Carter banned
2072-597: The bismuth phosphate process , was developed and tested at the Oak Ridge National Laboratory (ORNL) between 1943 and 1945 to produce quantities of plutonium for evaluation and use in the US weapons programs . ORNL produced the first macroscopic quantities (grams) of separated plutonium with these processes. The bismuth phosphate process was first operated on a large scale at the Hanford Site , in
2146-457: The diluent is a polar aromatic such as nitrobenzene . Other diluents such as meta -nitrobenzotri fluoride and phenyl trifluoromethyl sulfone have been suggested as well. An exotic method using electrochemistry and ion exchange in ammonium carbonate has been reported. Other methods for the extraction of uranium using ion exchange in alkaline carbonate and "fumed" lead oxide have also been reported. The bismuth phosphate process
2220-424: The fission products volatilized are the same ones volatilized in non-fluorinated, higher-temperature volatilization, such as iodine , tellurium and molybdenum ; notable differences are that technetium is volatilized, but caesium is not. Some transuranium elements such as plutonium , neptunium and americium can form volatile fluorides, but these compounds are not stable when the fluorine partial pressure
2294-560: The New York Times reported "...11 years after the government awarded a construction contract, the cost of the project has soared to nearly $ 5 billion. The vast concrete and steel structure is a half-finished hulk, and the government has yet to find a single customer, despite offers of lucrative subsidies." TVA (currently the most likely customer) said in April 2011 that it would delay a decision until it could see how MOX fuel performed in
Thermal Oxide Reprocessing Plant - Misplaced Pages Continue
2368-609: The Nuclear Research Institute of Řež in Czech Republic, Indira Gandhi Centre for Atomic Research in India and KAERI in South Korea. The electrolysis methods are based on the difference in the standard potentials of uranium, plutonium and minor actinides in a molten salt. The standard potential of uranium is the lowest, therefore when a potential is applied, the uranium will be reduced at
2442-476: The PUREX process, there have been efforts to develop alternatives to the process, some of them compatible with PUREX (i.e. the residue from one process could be used as feedstock for the other) and others wholly incompatible. None of these have (as of the 2020s) reached widespread commercial use, but some have seen large scale tests or firm commitments towards their future larger scale implementation. Pyroprocessing
2516-665: The Thermal Oxide Reprocessing Plant, was given the go-ahead in 1978. Construction of THORP started in 1979, and was completed in 1994. The plant went into operation in August 1997. Build cost was £1.8 billion. THORP's first irradiated fuel rod was sheared in March 1994, which was followed in January of 1995 by the chemical separation plant processing the irradiated fuel feed solution that had been produced in
2590-456: The UK's PWR and AGR fleet. The decommissioning is expected to start around 2075. Between 1977 and 1978 an inquiry was held into an application by British Nuclear Fuels plc for outline planning permission to build a new plant to reprocess irradiated oxide nuclear fuel from both UK and foreign reactors. The inquiry was to answer three questions: The result of the inquiry was that the new plant,
2664-470: The United States, the Obama administration stepped back from President Bush's plans for commercial-scale reprocessing and reverted to a program focused on reprocessing-related scientific research. Not all nuclear fuel requires reprocessing; a breeder reactor is not restricted to using recycled plutonium and uranium. It can employ all the actinides , closing the nuclear fuel cycle and potentially multiplying
2738-507: The alkaline fission products. Some noble metals may not form fluorides at all, but remain in metallic form; however ruthenium hexafluoride is relatively stable and volatile. Distillation of the residue at higher temperatures can separate lower-boiling transition metal fluorides and alkali metal (Cs, Rb) fluorides from higher-boiling lanthanide and alkaline earth metal (Sr, Ba) and yttrium fluorides. The temperatures involved are much higher, but can be lowered somewhat by distilling in
2812-596: The ban in 1981, but did not provide the substantial subsidy that would have been necessary to start up commercial reprocessing. In March 1999, the U.S. Department of Energy (DOE) reversed its policy and signed a contract with a consortium of Duke Energy , COGEMA , and Stone & Webster (DCS) to design and operate a mixed oxide (MOX) fuel fabrication facility. Site preparation at the Savannah River Site (South Carolina) began in October 2005. In 2011
2886-510: The cathode out of the molten salt solution before the other elements. These processes were developed by Argonne National Laboratory and used in the Integral Fast Reactor project. PYRO-A is a means of separating actinides (elements within the actinide family, generally heavier than U-235) from non-actinides. The spent fuel is placed in an anode basket which is immersed in a molten salt electrolyte. An electric current
2960-521: The design for seismic uncoupling. The incident was classified as Level 3 out of 7 on the International Nuclear Event Scale (INES), a "serious incident", due to the amount of radioactive inventory that leaked from primary to secondary containment without discovery over a number of months. This was initially considered by BNFL to be surprisingly high, but the specifications of the scale required it. The British Nuclear Group
3034-404: The disadvantage of requiring the use of a salting-out reagent (aluminium nitrate ) to increase the nitrate concentration in the aqueous phase to obtain a reasonable distribution ratio. This process was used at Windscale in 1951-1964. This process has been replaced by PUREX, which was shown to be a superior technology for larger scale reprocessing. The sodium uranyl acetate process was used by
Thermal Oxide Reprocessing Plant - Misplaced Pages Continue
3108-681: The distribution of radioactive metals for analytical purposes, Solvent Impregnated Resins (SIRs) can be used. SIRs are porous particles, which contain an extractant inside their pores. This approach avoids the liquid-liquid separation step required in conventional liquid-liquid extraction . For the preparation of SIRs for radioanalytical separations, organic Amberlite XAD-4 or XAD-7 can be used. Possible extractants are e.g. trihexyltetradecylphosphonium chloride(CYPHOS IL-101) or N,N0-dialkyl-N,N0-diphenylpyridine-2,6-dicarboxyamides (R-PDA; R = butyl, octy I, decyl, dodecyl). The relative economics of reprocessing-waste disposal and interim storage-direct disposal
3182-566: The early Soviet nuclear industry to recover plutonium from irradiated fuel. It was never used in the West; the idea is to dissolve the fuel in nitric acid , alter the oxidation state of the plutonium, and then add acetic acid and base. This would convert the uranium and plutonium into a solid acetate salt. Explosion of the crystallized acetates-nitrates in a non-cooled waste tank caused the Kyshtym disaster in 1957. As there are some downsides to
3256-727: The effects of the fission product technetium, has given an overall separation performance well in excess of the minimum flowsheet requirement. THORP's discharges represented a small fraction of overall discharges from the wider Sellafield site. On 14 November 2018 it was announced that reprocessing operations had ended at THORP after all existing reprocessing contracts had been fulfilled. It had reprocessed 9,331 tonnes of used nuclear fuel from 30 customers in nine countries, earning £9bn in revenue. The receipt and storage facility within THORP continues to operate. Decommissioning will take place after several decades to allow radiation levels to decline, and
3330-424: The energy extracted from natural uranium by about 60 times. The potentially useful components dealt with in nuclear reprocessing comprise specific actinides (plutonium, uranium, and some minor actinides ). The lighter elements components include fission products , activation products , and cladding . The first large-scale nuclear reactors were built during World War II . These reactors were designed for
3404-445: The formation of acidic gases which could contribute to acid rain (although the acidic gases could be recovered by a scrubber). The DIAMEX process is being worked on in Europe by the French CEA . The process is sufficiently mature that an industrial plant could be constructed with the existing knowledge of the process. In common with PUREX this process operates by a solvation mechanism. S elective A cti N ide EX traction. As part of
3478-414: The fuel or increases its surface area to enhance penetration of reagents in following reprocessing steps. Simply heating spent oxide fuel in an inert atmosphere or vacuum at a temperature between 700 °C (1,292 °F) and 1,000 °C (1,830 °F) as a first reprocessing step can remove several volatile elements, including caesium whose isotope caesium-137 emits about half of the heat produced by
3552-627: The fuel supply" via MOX fuel, breeder reactors or even the thorium fuel cycle could become more attractive. However, if uranium prices remain low, reprocessing will remain less attractive. Cubic metre The cubic metre (in Commonwealth English and international spelling as used by the International Bureau of Weights and Measures ) or cubic meter (in American English ) is the unit of volume in
3626-590: The industry at present. When used on fuel from commercial power reactors the plutonium extracted typically contains too much Pu-240 to be considered "weapons-grade" plutonium, ideal for use in a nuclear weapon. Nevertheless, highly reliable nuclear weapons can be built at all levels of technical sophistication using reactor-grade plutonium. Moreover, reactors that are capable of refueling frequently can be used to produce weapon-grade plutonium, which can later be recovered using PUREX. Because of this, PUREX chemicals are monitored. The PUREX process can be modified to make
3700-432: The later part of 1944. It was successful for plutonium separation in the emergency situation existing then, but it had a significant weakness: the inability to recover uranium. The first successful solvent extraction process for the recovery of pure uranium and plutonium was developed at ORNL in 1949. The PUREX process is the current method of extraction. Separation plants were also constructed at Savannah River Site and
3774-517: The level of various naturally occurring minerals and ores within a few hundred, rather than thousands of, years. The mixed actinides produced by pyrometallic processing can be used again as nuclear fuel, as they are virtually all either fissile , or fertile , though many of these materials would require a fast breeder reactor to be burned efficiently. In a thermal neutron spectrum, the concentrations of several heavy actinides ( curium -242 and plutonium-240 ) can become quite high, creating fuel that
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#17327799595003848-533: The majority of the uranium and plutonium from the fission products by transferring them into the solvent phase, which comprises tri-butyl phosphate in odourless kerosene (TBP/OK). The transfer is done in the HA column with the HS column providing further removal of fission products. 2 further pulsed columns (designated BS/BX) and a mixer/settler assembly (1BXX) then separate the uranium and plutonium into separate streams. Plutonium
3922-403: The management of minor actinides it has been proposed that the lanthanides and trivalent minor actinides should be removed from the PUREX raffinate by a process such as DIAMEX or TRUEX. To allow the actinides such as americium to be either reused in industrial sources or used as fuel, the lanthanides must be removed. The lanthanides have large neutron cross sections and hence they would poison
3996-487: The nitrate concentration in the aqueous phase to obtain a reasonable distribution ratio (D value). Also, hexone is degraded by concentrated nitric acid. This process was used in 1952-1956 on the Hanford plant T and has been replaced by the PUREX process. Pu + 4NO − 3 + 2S → [Pu(NO 3 ) 4 S 2 ] A process based on a solvation extraction process using the triether extractant named above. This process has
4070-413: The nuclear accident at Fukushima Daiichi . PUREX , the current standard method, is an acronym standing for P lutonium and U ranium R ecovery by EX traction . The PUREX process is a liquid-liquid extraction method used to reprocess spent nuclear fuel , to extract uranium and plutonium , independent of each other, from the fission products. This is the most developed and widely used process in
4144-431: The other fission products are sent to waste. Voloxidation (for volumetric oxidation ) involves heating oxide fuel with oxygen, sometimes with alternating oxidation and reduction, or alternating oxidation by ozone to uranium trioxide with decomposition by heating back to triuranium octoxide . A major purpose is to capture tritium as tritiated water vapor before further processing where it would be difficult to retain
4218-441: The plant. The uranium is then made available for customers to be manufactured into new fuel, and the plutonium incorporated into mixed oxide fuel . On 14 November 2018 it was announced that reprocessing operations had ended at THORP after earning £9bn in revenue. The receipt and storage facility (which makes up nearly half of THORP's physical footprint), will operate through to the 2070s to receive and store spent nuclear fuel from
4292-529: The plutonium extraction stage of the PUREX process. Adding a second extraction agent, octyl(phenyl)-N, N-dibutyl carbamoylmethyl phosphine oxide (CMPO) in combination with tributylphosphate, (TBP), the PUREX process can be turned into the TRUEX ( TR ans U ranic EX traction) process. TRUEX was invented in the US by Argonne National Laboratory and is designed to remove the transuranic metals (Am/Cm) from waste. The idea
4366-448: The plutonium. Addition of an alkali produced an oxide. The combined lanthanum plutonium oxide was collected and extracted with nitric acid to form plutonium nitrate. This is a liquid-liquid extraction process which uses methyl isobutyl ketone codenamed hexone as the extractant. The extraction is by a solvation mechanism. This process has the disadvantage of requiring the use of a salting-out reagent ( aluminium nitrate ) to increase
4440-622: The previous year by the Head End plant. By the Spring of 1998 over 1400 t of irradiated fuel has been reprocessed in THORP, and the plant was steadily and successfully ramped up to its normal operating throughput throughout this time. At this time, the performance of the THORP Chemical Separation Plant had been excellent, above all, the uranium-plutonium separation stage, which received extensive development to deal with
4514-413: The production of plutonium for use in nuclear weapons . The only reprocessing required, therefore, was the extraction of the plutonium (free of fission-product contamination) from the spent natural uranium fuel. In 1943, several methods were proposed for separating the relatively small quantity of plutonium from the uranium and fission products. The first method selected, a precipitation process called
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#17327799595004588-540: The reactor core while awaiting eventual transfer to permanent storage. Many of the elements that form volatile high- valence fluorides will also form volatile high-valence chlorides. Chlorination and distillation is another possible method for separation. The sequence of separation may differ usefully from the sequence for fluorides; for example, zirconium tetrachloride and tin tetrachloride have relatively low boiling points of 331 °C (628 °F) and 114.1 °C (237.4 °F). Chlorination has even been proposed as
4662-415: The reprocessing of commercial reactor spent nuclear fuel . The key issue driving this policy was the risk of nuclear weapons proliferation by diversion of plutonium from the civilian fuel cycle, and to encourage other nations to follow the US lead. After that, only countries that already had large investments in reprocessing infrastructure continued to reprocess spent nuclear fuel. President Reagan lifted
4736-577: The reprocessing of other nuclear reactor material, such as Zircaloy cladding. The high radioactivity of spent nuclear material means that reprocessing must be highly controlled and carefully executed in advanced facilities by specialized personnel. Numerous processes exist, with the chemical based PUREX process dominating. Alternatives include heating to drive off volatile elements, burning via oxidation, and fluoride volatility (which uses extremely reactive Fluorine ). Each process results in some form of refined nuclear product, with radioactive waste as
4810-404: The risk of a criticality incident occurring within the plant. This can happen if sufficient fissile material comes together to start an uncontrolled chain reaction, producing a large release of neutrons. The risks and mechanisms are well understood and the plant design is arranged to prevent its occurrence, i.e.: intrinsically safe. On 9 May 2005 it was announced that THORP suffered a large leak of
4884-459: The spent fuel over the following 100 years of cooling (however, most of the other half is from strontium-90 , which has a similar half-life). The estimated overall mass balance for 20,000 g of processed fuel with 2,000 g of cladding is: In the fluoride volatility process, fluorine is reacted with the fuel. Fluorine is so much more reactive than even oxygen that small particles of ground oxide fuel will burst into flame when dropped into
4958-593: The temperature of maximum density (3.98 °C) and standard atmospheric pressure (101.325 kPa) has a mass of 1000 kg , or one tonne . At 0 °C, the freezing point of water, a cubic metre of water has slightly less mass, 999.972 kilograms. A cubic metre is sometimes abbreviated to m^3 , M3 , m**3 , cum , m3 , CBM , cbm when superscript characters or markup cannot be used (e.g. in some typewritten documents and postings in Usenet newsgroups). The "cubic metre" symbol
5032-506: The tritium. Tritium is a difficult contaminant to remove from aqueous solution, as it cannot be separated from water except by isotope separation. However, tritium is also a valuable product used in industry science and nuclear weapons , so recovery of a stream of hydrogen or water with a high tritium content can make targeted recovery economically worthwhile. Other volatile elements leave the fuel and must be recovered, especially iodine , technetium , and carbon-14 . Voloxidation also breaks up
5106-430: Was convicted for breaches of health and safety regulations following the accident, and fined £500,000. Production at the plant restarted in late 2007, but in early 2008 stopped again for the repair of an underwater lift that moved fuel for reprocessing. Nuclear reprocessing Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel . Originally, reprocessing
5180-541: Was developed in Russia and the Czech Republic ; it is designed to completely remove the most troublesome radioisotopes (Sr, Cs and minor actinides ) from the raffinate remaining after the extraction of uranium and plutonium from used nuclear fuel . The chemistry is based upon the interaction of caesium and strontium with polyethylene glycol and a cobalt carborane anion (known as chlorinated cobalt dicarbollide). The actinides are extracted by CMPO, and
5254-405: Was maintained in the +6 oxidation state by addition of a dichromate salt. The bismuth phosphate was next re-precipitated, leaving the plutonium in solution, and an iron(II) salt (such as ferrous sulfate ) was added. The plutonium was again re-precipitated using a bismuth phosphate carrier and a combination of lanthanum salts and fluoride added, forming a solid lanthanum fluoride carrier for
5328-406: Was safely recovered into primary containment using originally installed steam ejectors. Radiation levels in the cell precluded entry of humans. The pipe fractured due to lateral motion of an accountancy tank, which measures volume by weight and moves horizontally and vertically in the process. The tank's original design had restraint blocks to prevent lateral motion, but these were later removed from
5402-400: Was the focus of much debate over the first decade of the 2000s. Studies have modeled the total fuel cycle costs of a reprocessing-recycling system based on one-time recycling of plutonium in existing thermal reactors (as opposed to the proposed breeder reactor cycle) and compare this to the total costs of an open fuel cycle with direct disposal. The range of results produced by these studies
5476-445: Was used solely to extract plutonium for producing nuclear weapons . With commercialization of nuclear power , the reprocessed plutonium was recycled back into MOX nuclear fuel for thermal reactors . The reprocessed uranium , also known as the spent fuel material, can in principle also be re-used as fuel, but that is only economical when uranium supply is low and prices are high. Nuclear reprocessing may extend beyond fuel and include
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