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Purex process advantages

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]

An advantage of the Purex process is the low salt content of the aqueous waste stream so the liquid volume can be reduced by evaporation. The HNO3 values are recycled to the process. The Purex process produces nearly pure plutonium and recovers uranium and it is the process that has been adapted to treat domestic spent nuclear fuel. [Pg.2649]

The Purex process has four significant advantages over the Redox process (1) Waste volumes can be made much lower, as the nitric acid used as salting agent can be removed by evaporation. (2) The solvent, TBP, is less volatile and less flammable than hexone. (3) TBP is more stable against attack by nitric acid. (4) Operating costs are lower. [Pg.461]

There are advantages and disadvantages to all of the processes just described. Some are easier to implement than others. Some require adjustment of parameters such as pH or nitrate concentration. Some have problems with third phase formation and solvent degradation or become impractical for industrial applications because of the limited loading capacities of the extractants. In all cases, however, adding separation steps to the PUREX process to remove the minor actinides will generate additional secondary waste streams that will have to be managed. [Pg.2827]

In the PUREX process, the oxidizing property of nitric acid and the formation of nitrous acid are not favorable to maintain plutonium as a trivalent species. The sufficient amount of hydrazine is added to the system to ensure the stability of Pu(III) with the destruction of nitrous acid according to Equation 14.7. Despite the fact that hydrazine is particularly advantageous because the reaction products, N2/ N2O, and H2O, do not contribute to the volume of stored wastes (Schlea et al., 1963), the interaction of hydrazine and nitrous acid can initiate, in a TBP-nitric acid system, and under specific operating conditions, the formation of hydrazoic acid (HN3) which is a hazardous and potentially explosive compoimd (Equation 14.7) (Dukes and Wallace, 1962). Further oxidation leads to the formation of nitrous oxide and nitrogen gases as depicted in Equation 14.8... [Pg.413]

Various additional (secondary solvent cleaning) procedures have been proposed, including vacuum distillation [30], treatment with macroreticular anion-exchange resins [31], and treatment with activated alumina [32,33]. These secondary cleanup operations increase solvent quality, and continue to be studied to better evaluate their process and economic advantages. In the French UP3 Purex plant, vacuum distillation is used to regulate TBP concentration and solvent quality with beneficial effects. The latter include... [Pg.523]

If reprocessing of spent Th fuels is needed in the future, many drawbacks of the Thorex process can be avoided by using A, A -dialkylamides instead of TBP. It is known from studies of Pu(IV)-U(VI) separation with amides that U(VI)-Th(IV) separation in acidic medium is easier than with TBP. The advantages of amides over phosphates could probably be considered more freely for Thorex than for Purex plants because no Thorex plant has been built yet. The extraction behavior of Pa(V) has not been yet investigated but in view of the general chemical properties of the two extractants, smaller distribution ratios are expected with the A, A -dialkyl-amides. [Pg.530]

Simplified flow sheets are given in Figs. 2 and 3 for two of the basic types of waste that will be encountered. The Purex type of waste is the simplest of all of the wastes to process, being a nitric acid solution of fission products, corrosion products, and a small amount of other impurities. Advantage is taken of the fact that one can evaporate this waste, and thereby achieve a greatly increased concentration of material, before actual chemical separation of the constituents is started. [Pg.108]

The most widely employed method for plutonium reprocessing used today in almost all of the world s reprocessing plants is the Purex (plutonium-uranium reduction extraction) process. Tributylphosphate (TBP) is used as the extraction agent for the separation of plutonium from uranium and fission products. In effecting a separation, advantage is taken of differences in the extractability of the various oxidation states and in the thermodynamics and kinetics of oxidation reduction of uranium, plutonium, and impurities. Various methods are in use for the conversion of plutonium nitrate solution, the final product from fuel reprocessing plants, to the metal. The reduction of plutonium halides with calcium proved to be the best method... [Pg.11]


See other pages where Purex process advantages is mentioned: [Pg.521]    [Pg.529]    [Pg.949]    [Pg.954]    [Pg.625]    [Pg.385]    [Pg.954]    [Pg.2825]    [Pg.390]    [Pg.295]    [Pg.367]    [Pg.414]    [Pg.186]    [Pg.537]   
See also in sourсe #XX -- [ Pg.461 ]

See also in sourсe #XX -- [ Pg.534 ]




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