Nonaqueous reprocessing

A Nonaqueous Reprocessing Method for Thorium-Based Fuels... 

Xumerous conventional processes such as solvent extraction, selective precipitation, and preferential ion exchange could be readily applied to molten fluoride fuels after solution in water. However, these liquids are readily amenable to remote handling and serve as media in which chemical reactions can be conducted. Most development efforts have, accordingly, been concerned with direct and nonaqueous reprocessing methods. 

The pyrochemical coprocessing of spent nuclear fuel by the Salt Transport Process appears to be a potentially viable reprocessing method, not only as an "exportable proliferation resistant technology," but as a domestic reprocessing operation. All operations are nonaqueous and waste generation is in solid form, thus requiring no conversion from aqueous solutions to solids. 

Alternatives to aqueous processing or dry or nonaqueous processing techniques have heen tried hut none, until recently, have been used on a true industrial scale for fuel reprocessing. Examples of these include separations based on (1) differences in volatility of the hahdes, especially fluorine compounds (2) molten salt (liquid-liquid) extraction where fuel dissolved in a molten salt is then contacted with a heat resistant low volatility second phase such as 100% TBP or a liquid metal and, (3) electrorefining, where controlling the cell potential results in removal of a metal from a molten salt by the selective deposition (reduction) on a cathode. 

Schematic diagram of ANL s nonaqueous eiectrometaiiurgicai process used to reprocess spent fuel from an experimentai fast breeder reactor (EBR-II) (NAS 2000] (Reprinted with permission from Eiectrometaiiurgicai Techniques for DOE Spent Fuei - Finai Report, p. 21, courtesy of the National Academy Press, Washington, DC]...

Reprocessing technologies can be grouped into two categories those based primarily on aqueous chemistry and those based on nonaqueous materials, such as molten salts and molten metals. 

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