COEX™ process

Recently, the CO-EXtraction (COEX) process was proposed by AREVA-France (104). The COEX process initially coextracts all of the U and Pu, and subsequently splits them into a U stream and a Pu stream containing an equal amount of U. In addition, a hydrometallurgical co-conversion process is coinstalled in an integrated recycling plant, which produces homogenous mixed actinide oxides (105, 106). Thus, the PR is enhanced. 

Global recycling scheme of PUREX (a) and COEX (b) processes. 

For future advanced nuclear systems, minor actinides are considered more as a resource to be recycled and transmuted than to be disposed of directly into a nuclear repository. A key feature of advanced fuel cycles technologies would be to separate M A and ultimately americium from curium. Several countries are investigating the separation of MA from a PUREX/COEX based process raffinate or a modified PUREX process raffinate using new extractant molecules with two potential options for actinide separations ... 

In mid-2006, a report by the Boston Consulting Group (Peters et al., 2006) for AREVA and based on proprietary AREVA information showed that recycling used fuel in the United States using the COEX aqueous process would be economically competitive with direct disposal of used fuel. A 12 billion, 2500 t yr plant was considered, with total capital expenditure of 16 billion for all related aspects. This would have the benefit of greatly reducing demand on space of a repository with a capacity of 70,000 MTHM. 

Mechanical and Dielectric Losses. A mechanical or dielectric loss peak occurs when external deformation time (frequency coex) equals the relaxation time Tm owing to a process involving changes of place. At low temperatures, only low energetic potential barriers AU can be overcome within finite time. It is typical of the temperature-frequency correlation (Arrhenius plot) that at very low temperatures, there is only a small effect of experimental frequency coex. on the temperature position of loss peaks. For At/ = 1 kJ/mol (240 cal/mol), the temperature at a loss peak is shifted from 4 to 7 K when ct>ex is increased from 1 to 10 Hz. 

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