Centrifugal contactor using

An inactive countercurrent test was first carried out in the G1 facility at the CEA Marcoule in a battery of eight centrifugal contactors using a synthetic nitric acid solution containing Nd(III) and Eu(III) at 2 g/L and 100 mg/L, respectively, to assess the hydrodynamic behavior of the system, which appeared to be satisfactory (206). 

As the focus of this book is on nuclear fuel reprocessing and nuclear-waste cleanup, we will focus on applications in these areas. This section will look at the reprocessing of nuclear fuel and the cleanup and segregation of nuclear waste with SRL and ANL contactors. Finally, other centrifugal contactors used for nuclear processing in France, Japan, Russia, and China will be discussed. 

Typical regions for application of contactors of different types are given in Table 13.2. The choice of a contactor for a particular application requires the consideration of several factors including chemical stability, the value of the products and the rate of phase separation. Occasionally, the extraction system may be chemically unstable and the contact time must then be kept to a minimum by using equipment such as a centrifugal contactor. 

The types of equipment used, which range from stirred tanks and mixer-settlers to centrifugal contactors and various types of columns, affect both capital and operating costs [9]. In the decision to build a plant, the choice of the most suitable contactor for the specific situation is most important. In some systems, because of the chemistry and mass transfer rates involved, several alternative designs of contacting equipment are available. In the selection of a contactor, one must consider the capacity and stage requirements solvent type and residence time phase flow ratio physical properties direction of mass transfer phase dispersion and coalescence holdup kinetics equilibrium presence of solids overall performance and maintenance as a function of contactor complexity. This may appear very complicated, but with some experience, the choice is relatively simple. 

Often the products of nuclear reactions have very short half-lives. This is especially true for the heaviest elements obtained by bombardment of heavy targets with heavy ions. To identify and characterize such short-lived nuclides, fast separations are required solvent extraction techniques are well suited to provide the required fast separations. For example, the SISAK method [68] has been successfully used in conjunction with in-line gas jet separators at heavy ion accelerators to identify short half-life actinide isotopes produced by collision of heavy atoms. The Sisak method involves use of centrifugal contactors, with phase residence times as low as tenths of a second, in conjunction with in-line radiometric detection equipment. 

The reaction rate of AHA is large enough to use centrifugal contactors. Process experiments with real SNF in a series of centrifugal contactors have demonstrated a separation of highly pure U with a yield of >99.99% (126, 183-188). The UREX+ process also enables the effective separation of Tc (189). 

Bilancia, G., Facchini, A., Ferrando, M. et al. 2005. Selective actinide extraction with a tri-synergistic mixture using a centrifugal contactor battery. Solvent Extr. Ion Exch. 23 (6) 773-780. 

Law, J.D., Wood, D.J., Herbst, R.S. 1997. Development and testing of SREX flowsheets for treatment of Idaho Chemical Processing Plant sodium-bearing waste using centrifugal contactors. Sep. Sci. Technol. 32 C1 —4) 223-240. 

Wood, D.J., Law, J.D., Todd, T.A. 1998. Demonstration of a SREX process for the treatment of actual high activity waste at the INEEL using centrifugal contactors. Science and Technology for Disposal of Radioactive Tank Waste, Schulx, W.W., Lombardo, NJ. Eds. Plenum, New York, pp. 255-268. 

C. 2008. Towards an optimized flow-sheet for a SANEX demonstration process using centrifugal contactors. ATALANTE 2008 Nuclear Fuel Cycles for a Sustainable Future, May, Montpellier, France. 

Nakahara, M., Sano, Y., Koma, Y., Kamiya, M., Shibata, A., Koizumi, T., Koyama, T. 2007. Separation of actinide elements by solvent extraction using centrifugal contactors in the NEXT process. Journal of Nuclear Science and Technology 44(3) 373-381. 

In this chapter, Section 10.2 gives an overview of the operation of the Argonne centrifugal contactor. Section 10.3 focuses on the design principles for this contactor. Section 10.4 discusses the worldwide applications of this contactor to solvent-extraction processes of interest to the nuclear and other industries. Comparisons with other types of contactors are made throughout the text, and a separate section is devoted to them in Section 10.4. However, because of their widespread use and the author s particular experience with them, the ANL contactor and its variations remain the primary focus. 

A solvent-extraction flowsheet is broken down into sections such as extraction, scrub, and strip. For each section, one or more component in a process fluid must be moved from one phase to the other phase with a specified degree of completeness. The first design problem is to determine the number of stages for each section to accomplish the required component transfer. With the well-defined stages of the centrifugal contactor, the following extraction factor (E) can be used to estimate the number of stages required ... 

The centrifugal contactor was first used to reprocess spent nuclear fuel at the SRS in 1966 (Webster et al., 1969). For almost 40 years, this 18-stage 25-cm SRL contactor was used for the extraction and scrub sections (the A-bank) of the PUREX (plutonium-uranium extraction) process at the SRS. Contactor operation stopped when the facility in which they were housed was shut down in 2003. This 18-stage contactor replaced a 24-stage mixer-settler. Mixer-settlers continued to be used for the rest of the processing, as most of the radiation was removed in the A-bank. The ability to... 

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