Zirconium reprocessing

In France, Compagnie Europnene du Zirconium (CEZUS) now owned jointly by Pechiney, Eramatome, and Cogema, uses a separation (14) based on the extractive distillation of zirconium—hafnium tetrachlorides in a molten potassium chloride—aluminum trichloride solvent at atmospheric pressure at 350°C. Eor feed, the impure zirconium—hafnium tetrachlorides from the zircon chlorination are first purified by sublimation. The purified tetrachlorides are again sublimed to vapor feed the distillation column containing the solvent salt. Hafnium tetrachloride is recovered in an enriched overhead fraction which is accumulated and reprocessed to pure hafnium tetrachloride. 

Meanx hile, success in the development of the natural uranium fuelled CANDU concept had led to very low cost fuelling and effective utilization of uranium even without recovery through reprocessing. AECL therefore decided to set aside work on reprocessing and concentrate instead on the once-through fuel cycle with storage of the irradiated fuel. The evidence indicated that the zirconium clad UO fuel could be stored under water for many decades until a decision was needed regarding recycle or disposal. 

Lamouroux, C., Moulin, C., Tabet, J.C., Jankowki, C.K. 2000. Characterization of zirconium complexes of interest in spent nuclear fuel reprocessing by electrospray ionization mass spectrometry. Rapid Commun. Mass Spectrom. 14 1869-1877. 

Miyake, C., Hirose, M., Yoshimura, T., Ikeda, M., Imoto, S., Sano, M. 1990. The third phase of extraction process in juel reprocessing, (II) EXAFS study of zirconium monobutylphosphate and zirconium dibutylphosphate. J. Nucl. Sci. Technol. 27(3) 256-261. 

From power reactors with no reprocessing, the high-level waste consists of assemblies of zirconium-clad spent fuel rods to be packaged in stainless steel canisters. If the spent fuel is reprocessed, then the high-level waste will be converted to a silicate glass form similar to that from defense operations. The uranium... 

Nuclear fuel rods consist of uranium oxide pellets contained in zirconium alloy or steel tubes. As the fission process proceeds, uranium is used up and fission products accumulate. A lot of these fission products are good neutron absorbers and reduce the efficiency of the fission process (by absorbing neutrons before they reach uranium atoms) so that the rods are removed for reprocessing before all the content has undergone fission. Fission of a atom produces two lighter atoms of approximate relative atomic masses around 90-100 and 130-140, with the main fission products being the intensely radioactive and short lived I (fi 8 d), °La, Pr, Zr, Ru, and Nb, and longer-lived... 

Plants in the UK, USSR and France are now reprocessing irradiated UO2/PUO2 fuels and LMFBR fuel reprocessing has been the subject of international conferences. " The plant at Cap la Hague, France, employs a 30% TBP solution and no U/Pu separation is undertaken, so that a mixed U/Pu product is obtained. Fluoride is added to the process feed to complex zirconium and suppress its extraction." The Dounreay plant in the UK employs a 20% TBP/OK solution and uses sulfuric acid to effect the U/Pu separation. TBP poorly extracts Pu or U from sulfuric acid solutions, but in mixed HNO3/H2SO4 the equilibria shown in equations (206) and (207) must be considered. The equilibrium constants for these reactions, Kj, and K i, are given... 

For the purpose of improving the decontamination factor (DF) of FPs from U or Pu in the reprocessing of highly irradiated fuels such as those from FBR, a modified method adding inactive zirconium or hafnium ion is proposed. The feasibility of this concept has been experimentally demonstrated by both batchwise extraction and process studies with miniature mixer-settlers. 

The addition of inactive zirconium has resulted in improving DF by a factor of about 4 in the simulated FBR fuel reprocessing flow-sheets (30). 

Massive zirconium and zircaloy are resistant to hot nitric acid. In fuel reprocessing (Chap. 10), uranium metal or uranium dioxide fuel can be dissolved by hot nitric acid while leaving the zircaloy cladding unattacked. 

The Idaho Chemical Processing Plant is a versatile, multipurpose facility used for recovering highly enriched uranium from a variety of fuels in naval propulsion, research, and test reactors. Materials processed [Al] include aluminum-alloyed, zirconium-alloyed, stainless steel-based, and graphite-based fuels. The West Valley plant, although designed primarily for low-enriched uranium fuel from power reactors, also processed plutonium-enriched and thorium-based fuels. It is the only U.S. plant to have reprocessed fuel from commercial nuclear power plants. 

It is noteworthy that reprocessing of either PEST, PC, or their mixtures can be facilitated by adding 0.2-0.5 wt% of titanium and zirconium esters that re-polymerize, copolymerize and bond these polyesters to fibers, flakes or rubber crumbs. The method has been successfully used to blend 80% recycled PET with recycled PC. The agent is re-activated every time the mixture is reprocessed, thus the alloy s properties improve during recycling [Schut, 1996]. 

Early Work. The irradiated fuel, upon discharge from the reactor, comprises the residual unbumt fuel, its protective cladding of magnesium alloy, zirconium or stainless steels, and fission products. The fission process yields over 70 fission product elements, while some of the excess neutrons produced from the fission reaction are captured by the uranium isotopes to yield a range of hew elements—neptunium, plutonium, americium, and curium. Neutrons are captured also by the cladding materials and yield a further variety of radioactive isotopes. To utilize the residual uranium and plutonium in further reactor cycles, it is necessary to remove the fission products and transuranic elements and it is usual to separate the uranium and plutonium this is the reprocessing operation. 

Euglena gracilis, 584 humans, 599 Zinc enolates, 217 Zirconium breeder reactor fuels reprocessing, 954... 

The operations and facilities include ore exploration (not included in NFCIS list), mining, ore processing, uranium recovery, chemical conversion to UO2, UO3, UF4, UFg, and uranium metal, isotope enrichment, reconversion of UF to UO2 (after enrichment), and fuel fabrication and assembly that are all part of the front end of the NFC. The central part of the NFC is the production of electric power in the nuclear reactor (fuel irradiation). The back end of the NFC includes facilities to deal with the spent nuclear fuel (SNF) after irradiation in a reactor and the disposal of the spent fuel (SF). The spent fuel first has to be stored for some period to allow decay of the short-lived fission products and activation products and then disposed at waste management facilities without, or after, reprocessing to separate the fission products from the useful actinides (uranium and plutonium). Note the relatively large number of facilities in Table 2.1 dedicated to dealing with the spent fuel. Also listed in Table 2.1 are related industrial activities that do not involve uranium, like heavy water (D2O) production, zirconium alloy manufacturing, and fabrication of fuel assembly components. 

Tape, tube, and washers made of virgin fluorocarbon polymers can be used to prevent the galvanic coupling. Avoid insulated materials made of reprocessed fluorocarbon polymers, since free hydrofluoric acid may be formed from released fluoride ions. Properly oxidized zirconium or Zircaloy materials can also be used for this purpose. Zirconium oxide is an excellent insulating material. 

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