Uranium spent-fuel reprocessing

The major use of C1F3 is in the nuclear industry which converts unclean spent fuel reprocessing, uranium metal into gaseous uranium hexafluoride. Other applications are low temperature etchant for single crystalline silicon [63,64], It is also used as a fluorinating reagent and in the synthesis of GIF and conversion of metals to metal fluorides such as tantalum and niobium metals to tantalum pentafluoride and niobium pentafluoride, respectively. 

The fast-spectrum reactors with full recycle of actinides would be designed with on-site spent fuel reprocessing and fuel fabrication to minimize the on-site inventory of long-lived radioactive waste. Modern robotic equipment can be used for reactor refueling and for fuel reprocessing. The spent fuel reprocessing and fuel fabrication facilities must be developed to close the nuclear fuel cycle and use all the energy available in natural uranium. 

M. SPENT FUEL REPROCESSED, URANiUM AND PLUTONiUM RECYCLED Recovered Pu, 445 kg... 

A single partitioning of a compound between an organic solvent and water may not be sufficient for isolating it in acc tably pure form and good yield. Various multiple extraction techniques may therefore be required. Such techniques have been described in 21.6.4 and their technical application for uranium production ( 5.5.3) and spent fuel reprocessing ( 21.6.3). 

Many of the secondary sources of uranium described above also displace demand for UFg conversion. These include inventories of UFgand low enriched uranium (LEU), Russian and US ex-military HEU and plutonium, uranium and plutonium recovered by civil spent fuel reprocessing, and UFg supply from the re-enrichment of tails. In addition, underfeeding of enrichment facilities can also affect the UFg market. 

Up to now, reprocessed uranium has only been used for the fabrication of a limited number of test fuel assemblies. For this type of fuel, the uranium fraction from the spent fuel reprocessing process is again subjected to an isotope enrichment procedure to obtain a content which is sufficiently high for reactor operation (3.8% in the example shown in Tables 3.1 and 3.2.). Besides the naturally occurring isotopes and this material contains mainly gener-... 

The chemical process leading from the uranyl nitrate solution to the UFe to be delivered to the enrichment process results in a decontamination factor for alpha activity of about 100 beta and gamma activities are reduced to a lower proportion, i. e. by a factor of 2 to 4 (Beck, 1985). From the onset of spent fuel reprocessing, enriched natural uranium has also been contaminated in some instances with traces of Tc, and plutonium isotopes. 

After launching such factory, the cost of the core will only be determined by the operating costs of spent fuel reprocessing and the costs of fuel assembly fabrication. If the pyro-electrochemical fuel reprocessing methods developed by the State Scientific Centre of the Russian Federation Research Institute of Atomic Reactors (SSC RIAR) are used, the contribution of fuel costs to the cost of SVBR-75/100 will be even less than in the basic variant using a once-through cycle with the uranium dioxide fuel. This will make it possible to improve considerably the NPP competitiveness. The abovementioned approach to the construction of capacities for reprocessing and fuel assembly fabrication presumes that the owner of the NPPs would also be the owner of the fuel cycle factories. 

At the stage of spent fuel reprocessing, the accumulated plutonium is separated from uranium together with the accumulated minor actinides, which makes such plutonium ineffective for weapon devices. Also, the isotopic content of plutonium does not meet the requirements to weapons-grade plutonium ... 

The centerpiece of spent fuel reprocessing is the Purex process (Plutonium-Uranium-Extraction). The solvent is tributyl phosphate in a hydrocarbon diluent, and the process was first used at the Ames Laboratory for uranium purification, then at Oak Ridge National Laboratory for spent fuel. Although other processes were used in earlier days, the Purex... 

Argon-40 [7440-37-1] is created by the decay of potassium-40. The various isotopes of radon, all having short half-Hves, are formed by the radioactive decay of radium, actinium, and thorium. Krypton and xenon are products of uranium and plutonium fission, and appreciable quantities of both are evolved during the reprocessing of spent fuel elements from nuclear reactors (qv) (see Radioactive tracers). 

Uranium-239 [13982-01 -9] has a half-life of 23.5 min neptunium-239 [13968-59-7] has a half-life of 2.355 d. Recycling or reprocessing of spent fuel involves separation of plutonium from uranium and from bulk fission product isotopes (see Nuclearreactors, chemical reprocessing). 

Spent fuel can be stored or disposed of intact, in a once-through mode of operation, practiced by the U.S. commercial nuclear power industry. Alternatively, spent fuel can be reprocessed, ie, treated to separate the uranium, plutonium, and fission products, for re-use of the fuels (see Nuclear REACTORS, CHEMICAL reprocessing). In the United States reprocessing is carried out only for fuel from naval reactors. In the nuclear programs of some other countries, especially France and Japan, reprocessing is routine. 

Development efforts in the nuclear industry are focusing on the fuel cycle (Figure 6.12). The front end of the cycle includes mining, milling, and conversion of ore to uranium hexafluoride enrichment of the uranium-235 isotope conversion of the enriched product to uranium oxides and fabrication into reactor fuel elements. Because there is at present a moratorium on reprocessing spent fuel, the back end of the cycle consists only of management and disposal of spent fuel. 

In 1942, the Mallinckrodt Chemical Company adapted a diethylether extraction process to purify tons of uranium for the U.S. Manhattan Project [2] later, after an explosion, the process was switched to less volatile extractants. For simultaneous large-scale recovery of the plutonium in the spent fuel elements from the production reactors at Hanford, United States, methyl isobutyl ketone (MIBK) was originally chosen as extractant/solvent in the so-called Redox solvent extraction process. In the British Windscale plant, now Sellafield, another extractant/solvent, dibutylcarbitol (DBC or Butex), was preferred for reprocessing spent nuclear reactor fuels. These early extractants have now been replaced by tributylphosphate [TBP], diluted in an aliphatic hydrocarbon or mixture of such hydrocarbons, following the discovery of Warf [9] in 1945 that TBP separates tetravalent cerium from... 

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