Solvent extraction nuclear fuel cycle

The second part deals with applications of solvent extraction in industry, and begins with a general chapter (Chapter 7) that involves both equipment, flowsheet development, economic factors, and environmental aspects. Chapter 8 is concerned with fundamental engineering concepts for multistage extraction. Chapter 9 describes contactor design. It is followed by the industrial extraction of organic and biochemical compounds for purification and pharmaceutical uses (Chapter 10), recovery of metals for industrial production (Chapter 11), applications in the nuclear fuel cycle (Chapter 12), and recycling or waste treatment (Chapter 14). Analytical applications are briefly summarized in Chapter 13. The last chapters, Chapters 15 and 16, describe some newer developments in which the principle of solvent extraction has or may come into use, and theoretical developments. 

Fuel. The nuclear fuel cycle starts with mining of the uranium ore, chemical leaching to extract the uranium, and solvent extraction with tributyl phosphate to produce eventually pure uranium oxide. If enriched uranium is required, the uranium is converted to the gaseous uranitim hexafluoride for enrichment by gaseous diffusion or gas centrifuge techniques, after which it is reconverted to uranium oxide. Since the CANDU system uses natural uranium, I will say no more about uranium enrichment although, as I m sure you appreciate, it is a major chemical industry in its own right. 

Meridiano, Y., Berthon, L., Lagrave, S., Crozes, X., Sorel, C., Testard, F., Zemb, T. 2008. Correlation between aggregation and extracting properties in solvent extraction systems Extraction of actinides (IB) and lanthanides (III) by a malonamide in non acidic media. ATALANTE 2008 Nuclear Fuel Cycles for a Sustainable Future, May, Montpellier, France. 

R. Chiarizia, M. P. Jensen, M. Borkowski, and K. L. Nash. A new interpretation of third-phase formation in the solvent extraction of actinides by TBP. Separations for the Nuclear Fuel Cycle in the 21st Century, 933 135-150, 2006. 

The INET annular centrifugal contactors are being used to partition high-level liquid waste so that the back end of the nuclear fuel cycle can be simplified. In particular, the TRPO process has been developed at INET for this application (Song, 2000), where TRPO is the extractant in the process solvent. Also known as Cyanex 923, TRPO is a trialkyl phosphine oxide that is made commercially by Cytec Industries (formerly American Cyanamid). It has a high affinity for the actinides. Further... 

Wymer, R.G. Vondra, B.L. PUREX solvent extraction chemistry. In Light Water Reactor Nuclear Fuel Cycle CRC Press, Inc. Boca Raton, FL, 1981 103-162. 

Not only is the uranyl ion thermodynamically robust, it is also kinetically inert. Experiments designed to measure the rate of isotopic oxygen exchange between the oxo atoms and water at room temperature, establish that the exchange half-life is greater than 40,000 hours [19]. This overall chemical stability accounts for an extensive coordination chemistry which is exploited, for example, in the solvent extraction separation processes used in the nuclear fuel cycle [20]. 

Chesne, A. and Germain, M. 1992. The use of solvent extraction in the nuclear fuel cycle forty years of progress. In Proceedings international solvent extraction conference, ed. T. Sekine, 539-548. Essex, UK Elsevier Science. 

Sano, Y. Ogino, H. Washiya, T. Myochin, M. (2009). Development of the Solvent Extraction Technique for U-Pu-Np Co-Recovery in the NEXT Process, Proceedings cf International Conference on The Nuclear Fuel Cycle Sustainable Options Industrial Perspectives (GLOBAL 2009), pp. 158-165, Paper 9222, Paris, France, September 6-11,... 

Choppin, G. R. 2005. Solvent extraction processes in the nuclear fuel cycle. Solvent Extraction Research and Development, Japan 12 1-10. 

Nuclear Waste. NRC defines high level radioactive waste to include (/) irradiated (spent) reactor fuel (2) Hquid waste resulting from the operation of the first cycle solvent extraction system, and the concentrated wastes from subsequent extraction cycles, in a faciHty for reprocessing irradiated reactor fuel and (3) soHds into which such Hquid wastes have been converted. Approximately 23,000 metric tons of spent nuclear fuel has been stored at commercial nuclear reactors as of 1991. This amount is expected to double by the year 2001. 

Since the launching of the Advanced Fuel Cycle Initiative (AFCI) program in the United States, the TRUEX solvent has been integrated in the live-step UREX+ process, initially consisting of live solvent-extraction steps to separate the constituents of dissolved spent nuclear fuels into seven fractions (101) ... 

---