(264a) Engineering Challenges in the Development of Actinide/Lanthanide Separation Processes to Support Advanced Nuclear Fuel Reprocessing

Law, J. D., Idaho National Laboratory
Mincher, B. J., Idaho National Laboratory
Schmitt, N., Idaho National Laboratory
Garn, T. G., Idaho National Laboratory
Tillotson, R., Idaho National Laboratory
The separation of Am from the lanthanides and curium is a key step in proposed advanced fuel cycle scenarios. The partitioning and transmutation of Am is desirable to minimize the long-term heat load of material interred in a future high-level waste repository. Given only subtle chemistry differences within and between the ions of the trivalent actinide and lanthanide series, this separation is challenging; however, higher oxidation states of americium can be prepared and separated via solvent extraction. One such method utilizes sodium bismuthate oxidation and solvent extraction with diamylamylphosphonate (DAAP).  Additional oxidants, including silver catalyzed ozone and copper(III) periodate have been investigated along with alternative extractants.  Although testing of some of these processes in the laboratory has been successful, numerous chemical engineering challenges arise when developing the process flowsheets and separation equipment for process operations. Issues include solid sodium bismuthate in the aqueous feed solution, corrosivity of Ce(IV), kinetics issues arising from instability of Am(VI), and development of selective stripping methods for the Am and Ce. A “hot” engineering-scale centrifugal contactor test bed has been constructed and tested as well a laboratory-scale test bed, utilizing 3-D printing technologies. Recent research aimed at resolving the engineering challenges of implementation of a separation process based on higher oxidation states of Am will be presented.