Quasi-ideal cascades with an additional flow for separation of multicomponent isotope mixtures

Sulaberidze, G. A.; Borisevich, V. D.; Xie, Qingming

doi:10.1134/s0040579506010027

Cited by 34 publications

(9 citation statements)

References 5 publications

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“…Alternatively, we can use the so-called dual cascade, where the product flow from the first cascade serves as a feed flow of the second one (Vetsko et al, 1987). In addition, some features of a "long" cascade can be used, where the concentration distributions of intermediate components have the maximum at its internal stages (Sulaberidze and Borisevich, 2001;Sulaberidze et al, 2006). This feature allows switching on an additional product flow at the point of the highest intermediate target of this component as compared with that at the cascade ends.…”

Section: Introductionmentioning

confidence: 98%

“…As is known, the model cascade theory is widely used to study the regularities of the multicomponent selective mass transfer in separation of multicomponent isotope mixtures in cascades (Sulaberidze et al, 2006;De la Garza et al, 1961;De la Garza, 1963;Yamamoto and Kanagawa, 1987;Wu and Fu, 1998;Von Halle, 1987;Agostini, 1994;Zeng et al, 2012;Scopatz, 2013;Wood and Megliorini, 2012;Song et al, 2010). On the base of this theory, it was demonstrated the fundamental possibility of obtaining relatively high concentrations of intermediate components in the additional product flow within the cascade having an "extension" of a working substance flow at its internal stage.…”

Section: Introductionmentioning

confidence: 99%

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Design of cascade with locally enlarged flow for enrichment of intermediate components of multi-isotope mixtures

Smirnov

Sulaberidze

Xie³

et al. 2015

Chemical Engineering Research and Design

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Design of cascade with locally enlarged flow for enrichment of intermediate components of multi-isotope mixtures

Smirnov

Sulaberidze

Xie³

et al. 2015

Chemical Engineering Research and Design

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“…This method improves the quality of the product obtained, but it is associated with high consumption of natural uranium, which is used as a diluent or for its production. Enrichment of regenerated uranium with 232,234,236 U content reduction in a cascade with additional feeding of natural raw material has the same drawback [3]. The consumption of natural uranium can be effectively decreased by using waste depleted uranium for one additional feed fl ow in the cascade [4].…”

mentioning

confidence: 99%

“…Its purifi ed waste fl ow is fed into the second (ordinary) cascade, in whose product fl ow the required commercial product (low-enrichment uranium) is accumulated [9]. Investigations have shown that a reduction of the 232 U concentration to (3)(4)·10 −9 % in the fi nal product is possible with 235 U enrichment in the cascades to 5% [10]. However, this method does not give signifi cant purifi cation by removal of 234,236 U.…”

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confidence: 99%

Purification and Enrichment of Regenerated Uranium in a Double Cascade

Palkin

2015

At Energy

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The effi ciency of two cascades is investigated on the basis of a computational experiment: in the fi rst one regenerated uranium is purifi ed and in the second one low-enrichment uranium is produced from the purifi ed waste of the fi rst one. It is shown that the use of R cascades for purifi cation makes it possible to reduce the content of 232,234 U considerably, but it leads to high 235 U concentration 60-90% in the steps. To eliminate this, the purifi cation by removal of 232,234 U should be done in optimal cascades, calculated according to the data obtained with the R cascades, with the feed shifted into the product step. This makes it possible to reduce the 235 U content in the steps of the cascade to 20% or less. The quality of the lowenrichment uranium produced from the purifi ed regenerated uranium can be improved by using dilution and enrichment operations, which make it possible to reduce the 236 U content.Regenerated uranium obtained from irradiated NPP fuel is a valuable raw material for enrichment and recycling in reactors. It contains and makes possible the conservation of the fi ssile isotope 235 U, whose concentration is no less than in natural uranium. However, 232,234,236 U, which are not separated during chemical reprocessing, are present in considerable quantities in regenerated uranium. The main diffi culties in using regenerated uranium for fuel production are associated with the elevated content of these radionuclides. The 232,234,236 U concentration must be reduced in order to reduce the radiological hazard to a minimum and to improve fuel quality [1]. The cascade technology for separating uranium hexafl uoride and dilution operations can be used for this purpose.Methods for enriching regenerated uranium with reduction of the 232,234,236 U content in a separate cascade are well known. One method is enrichment to concentration 10-90% 235 U in an ordinary (three-fl ow) cascade followed by dilution to 2-7% [2]. This method improves the quality of the product obtained, but it is associated with high consumption of natural uranium, which is used as a diluent or for its production. Enrichment of regenerated uranium with 232,234,236 U content reduction in a cascade with additional feeding of natural raw material has the same drawback [3]. The consumption of natural uranium can be effectively decreased by using waste depleted uranium for one additional feed fl ow in the cascade [4]. But this increases the expenditure of separative work. Yet another method entails the use of a cascade with intermediate product and two feed fl ows for regenerated and natural uranium [5]. In this case, there are no additional expenditures of separative work, but if the reduction of the 232,234,236 U concentration in the intermediate purifi ed product is substantial, then their content in the fi nal product fl ow, viz., low-enrichment uranium as the commercial product, increases.A substantial reduction of the 232,236 U content is accomplished in double cascades: 235 U is enriched to high concentration in the fi rst (...

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“…This theory was elaborated in [2][3][4] for the case of an additional flow and low relative concentration. However, the theoretical relations have only limited applications because the indicated cascades differ from the optimal cascades used in practice.…”

mentioning

confidence: 99%

Analytical calculation of the content of uranium isotopes in a cascade with two feed flows, two product flows, and one waste flow

Palkin¹,

Komarov²

2007

At Energy

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The problem of estimating the 232,234,236 U content in the product flows of an optimal cascade is examined. Relations are found for studying the characteristics of the concentration variations along the cascade for various ratios of the feed flows. It is shown that an effective procedure is to obtain from the intermediate product of the cascade a diluent for high-enrichment uranium.The technical characteristics of low-enrichment uranium produced in separation cascades for nuclear power must meet the ASTM C996-04 standard specifications. This imposes stringent constraints on the content of uranium isotopes 232 U, 234 U, and 236 U and requires that their concentrations in the product cascade flows be determined beforehand.A general theory of quasi-ideal cascades and R cascades which makes it possible to estimate the content of various isotopes during multicomponent separation in an ordinary (three-flow) cascade has been constructed in [1]. This theory was elaborated in [2-4] for the case of an additional flow and low relative concentration. However, the theoretical relations have only limited applications because the indicated cascades differ from the optimal cascades used in practice.When the 232,234,236 U content is much less than that of the target isotope 235 U and the separation effects at each step are small, the optimal cascade is identical to the ideal cascade with respect to 235 U and 238 U [5].A novel approach to obtaining an analytical solution of the system of differential equations for the separation of a multicomponent mixture in a cascade which is ideal with respect to the two main components was developed in this approximation [6]. This approach can be extended to any number of components and any number of external flows. A general method and algorithm for calculating the separation of uranium isotopes that makes it possible to obtain simple evaluation formulas have been proposed on the basis of this approach. Specifically, an analytical method of finding a solution for an ordinary cascade with three external flows on the basis of the method of [6] was presented in [7].The present paper examines the problem of obtaining an analytical estimate of the concentration of uranium isotopes in a more complex cascade used in practice -two feed flows, two product flows, and one waste flow. The salient features of the variation of the 234 U concentration for different ratios of the external flows are examined. It is shown that an effective procedure is to obtain obtaining from the intermediate product of the cascade a diluent for high-enrichment uranium.Formulation of the Problem. We shall study a cascade with two product flows, two feed flows, and one waste flow (Fig. 1). Its external parameters are the flows in the first (main) and second (intermediate) product flows P 1 and P 2 , the first and second feed flows F 1 and F 2 , and the waste flow W as well as the corresponding isotopic concentrations -C i P 1 , C i P 2 , C i F 1 ,The index i denotes the number of the isotope. We shall use it to denote the las...

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Quasi-ideal cascades with an additional flow for separation of multicomponent isotope mixtures

Cited by 34 publications

References 5 publications

Design of cascade with locally enlarged flow for enrichment of intermediate components of multi-isotope mixtures

Design of cascade with locally enlarged flow for enrichment of intermediate components of multi-isotope mixtures

Purification and Enrichment of Regenerated Uranium in a Double Cascade

Analytical calculation of the content of uranium isotopes in a cascade with two feed flows, two product flows, and one waste flow

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