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Purex process actinides

The above information was used to develop conceptual flowsheets for the extraction of all of the actinides (U, Np, Pu, Am, and Cm) from high-level liquid waste from PUREX processing using 0.4 M 0fuel using 0.8 M DHDECMP in DEB. In both flowsheets, no oxidation state of Pu is necessary since the III, IV, and VI state extract into the organic phase. [Pg.428]

A primary goal of chemical separation processes in the nuclear industry is to recover actinide isotopes contained in mixtures of fission products. To separate the actinide cations, advantage can be taken of their general chemical properties [18]. The different oxidation states of the actinide ions lead to ions of charges from +1 (e.g., NpOj) to +4 (e.g., Pu" " ) (see Fig. 12.1), which allows the design of processes based on oxidation reduction reactions. In the Purex process, for example, uranium is separated from plutonium by reducing extractable Pu(IV) to nonextractable Pu(III). Under these conditions, U(VI) (as U02 ) and also U(IV) (as if present, remain in the... [Pg.511]

Distribution ratios of the actinides in largest concentration and valency state, and some important fission products, which form the basis for the design of the Purex process flow sheet, are shown in Table 12.9. [Pg.520]

In tlie PUREX process, the spent fuel and blanket materials are dissolved in nitric acid to form nitrates of plutonium and uranium. These are separated chemically from the other fission products, including the highly radioactive actinides, and then the two nitrates are separated into tv/o streams of partially purified plutonium and uranium. Additional processing will yield whatever purity of the two elements is desired. The process yields purified plutonium, purified uranium, and high-level wastes. See also Radioactive Wastes in the entry1 on Nuclear Power Technology. Because of the yield of purified plutonium, the PUREX process is most undesirable from a nuclear weapons proliferation standpoint,... [Pg.1647]

The Purex process is used for almost all fuel reprocessing today. Irradiated UO2 fuel is dissolved in HNO3 with the uranium being oxidized to U02(N03)2 and the plutonium oxidized to Pu(NC>3)4. A solution of TBP in a high-boiling hydrocarbon, such as n-dodecane, is used to selectively extract the hexavalent U02(N03)2 and the tetravalent Pu(NC>3)4 from the other actinides and fission products in the aqueous phase. The overall reactions are... [Pg.481]

The SETFICS process (Solvent Extraction for Trivalent /-elements Intragroup Separation in CMPO-Complexant System) was initially proposed by research teams of the former Japan Nuclear Cycle Development Institute (JNC, today JAEA) to separate An(III) from PUREX raffinates. It uses a TRUEX solvent (composed of CMPO and TBP, respectively dissolved at 0.2 and 1.2 M in -dodecane) to coextract trivalent actinides and lanthanides, and a sodium nitrate concentrated solution (4 M NaN03) containing DTPA (0.05 M) to selectively strip the TPEs at pH 2 and keep the Ln(III) extracted by the TRUEX solvent (239). However, the DFs for heavy Ln(III) are rather poor. An optimized version of the SETFICS process has recently been proposed as an alternative process to extraction chromatography for the recovery of Am(III) and Cm(III) in the New Extraction System for TRU Recovery (NEXT) process. NEXT basically consists of a front-end crystallization of uranium, a simplified PUREX process using TBP for the recovery of U, Np, and Pu, and a back-end Am(III) + Cm(III) recovery step (240, 241). [Pg.167]

After a few years of storage, the main radioactive heat emitters in HLW are 90Sr and 137Cs. In addition, extremely long-lived actinides—neptunium, plutonium, americium, and curium—should be collected for transmutation in the future. Therefore, different flowsheets can be proposed for waste processing. It is possible to extract each radionuclide in the special extraction (sorption) cycle, for example, uranium and plutonium in the PUREX process, and after that, minor actinides (MAs) by the TRUEX process,4 strontium by the SREX process,5,6 and cesium by sorption7 or extraction.8... [Pg.360]

However, the conditions are often far from those of industrial situations. In order to better simulate solvent degradation during the PUREX process, a test loop was created in the 1990s in a CEA laboratory (Fontenay-aux-Roses, France), with the EDIT loop (Extraction Desextraction Irradiation Traitement) (21, 22). The laboratory simulation of industrial conditions consisted of a succession of representative physical and chemical treatments after the irradiation of the solvent (i.e., alkali and acid treatments, distillation). Indeed, these treatments can modify the final solvent composition because of the elimination of some compounds or the occurrence of secondary reactions. A few years later, the MARCEL (Module Avance de Radiolyse dans les Cycles d Extraction Lavage) test loop was built at Marcoule to follow the regeneration efficiencies of degraded solvents involved in actinide separation processes (4, 5). [Pg.439]

The CTH actinide separation process was developed as a possible means to reduce the expected long term dose to man from a geologic repository containing solidified radioactive waste from the reprocessing of spent nuclear fuel The distribution data for the elements present in significant amounts in the high level liquid waste (HLLW) from a Purex plant, the general principles and the flowsheet have been described in detail elsewhere A... [Pg.198]

During the aging of the HLLW solution from a Purex plant insoluble precipitates are known to form, which could endanger the operation of any actinide recovery process and increase actinide losses. It is therefore believed that an actinide separation process must use the HLLW solution as soon as possible after it is... [Pg.210]

The PUREX process exploits two features of U chemistry (1) the UC>22+ ion is the thermodynamically most stable form of U in aqueous solution both Pu022+ and Np022+ are easily reduced to Pu4+ and Np02+ under similar conditions (vide infra) and (2) in general, the actinide MC>22+ ions can be extracted from nitrate solutions into non-polar organic solvents [75] such as the phosphate esters, e.g. TBP. Since most other metal ions are not extracted under similar conditions, solvent extraction provides a convenient route for the purification of U and Pu from practically all other metals. Np can also be rendered extractable by manipulation of its oxidation state. Similarly, U can be separated from Pu by the selective reduction of Pu(IV) to Pu(III), rendering it inextractable into TBP/OK. [Pg.457]

In summary, potential improvements could be made to the PUREX process in the following areas (1) separation of Np from U and Pu prior to the U/Pu split and (2) in the requirement to use a large excess of U(IV) reductant to reduce Pu(IV) to Pu(III). The majority of published work on the applications of photo catalysis in actinide redox chemistry has concentrated on solving the first of these difficulties through Np valence control. A smaller volume of literature exists on the applications of photocatalysis in valence state control of U and the radioactive d block metal, technetium. This section will review both of these aspects. [Pg.461]

In analogy to the PUREX process, photocatalysed reduction of actinide metal ions can be employed in tandem with solvent extraction in order to achieve actinide separation. A process can be envisaged wherein photocatalysed reduction occurs in one of two solvent phases in contact—one aqueous and one non-aqueous—and wherein, as a result, the reduced metal ion is selectively retained by one of the solvent phases, either the phase it originated in, or as a consequence of a phase transfer reaction. Thus, experiments were conducted to assess both the efficacy of photocatalysed actinide metal ion reduction in a two-solvent phase system, and the efficacy of simultaneous selective product retention in one of those two phases. [Pg.475]

SANEX [Selective ActiNide Extraction] A process for removing lanthanide elements from actinides in the Purex process. Not yet fully developed. The name is used also for a range of toiletries. [Pg.317]

Reprocessing of nuclear fuel by the Purex process leads to the following amounts of waste per ton of U 1 m HLW (fission products and actinides in HNO3 solution), 3 m MLW as organic solution, 17m MLW as aqueous solution, 90m LLW (aqueous solution). By further processing a volume reduction is achieved 0.1m HLW, 0.2m MLW (organic), 8m MLW (aqueous), 3m LLW (aqueous). [Pg.230]


See other pages where Purex process actinides is mentioned: [Pg.80]    [Pg.202]    [Pg.205]    [Pg.351]    [Pg.108]    [Pg.546]    [Pg.546]    [Pg.202]    [Pg.882]    [Pg.926]    [Pg.928]    [Pg.945]    [Pg.946]    [Pg.954]    [Pg.960]    [Pg.960]    [Pg.4]    [Pg.120]    [Pg.145]    [Pg.198]    [Pg.199]    [Pg.251]    [Pg.262]    [Pg.382]    [Pg.394]    [Pg.130]    [Pg.454]    [Pg.454]    [Pg.454]    [Pg.477]    [Pg.355]    [Pg.6]    [Pg.883]    [Pg.882]   
See also in sourсe #XX -- [ Pg.945 ]

See also in sourсe #XX -- [ Pg.945 ]

See also in sourсe #XX -- [ Pg.6 , Pg.945 ]




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