A new back-end cycle strategy for enhancing separation, transmutation and utilization of materials (Adv.-ORIENT cycle)

To minimize the ecological burden originating in nuclear fuel recycling, a new R&D strategy, the Adv.-ORIENT (Advanced Optimization by Recycling Instructive Elements) cycle was set forth. In this context, mutual separation of f-elements, such as minor actinide (MA)/lanthanide (Ln) and Am/Cm, are essential to enhance the MA (particularly Am-241) burning. Isotope separation before transmutation is also inevitably required in the case of some long-lived fission products (LLFPs) like Sn-126, Cs-135, etc. The separation and utilization of rare metal fission products (RMFPs: Ru, Rh, Pd, Tc, Se, Te, etc.) are offering a new direction in the partitioning and transmutation (P&T) field. Tc-99 and Ru-106, well-known interfering nuclides in reprocessing, should be removed prior to the actinide stream. Separation of exothermic nuclides Sr-90, Cs-137 as well as MA will significantly help to mitigate the repository tasks. A key separation tool is ion exchange chromatography (IXC) by a tertiary pyridine resin having soft donor nitrogen atoms. This method has provided individual recovery of pure Am and Cm products with a Pu/U/Np fraction from irradiated fuel in just a 3-step separation. A catalytic electrolytic extraction (CEE) method by Pd-adatom has been employed to separate, purify and fabricate RMFP catalysts. Differently functioned ion exchangers, e.g., ammonium molybdophosphate (AMP), have been investigated for the separation of Cs+. Theoretical and laboratory studies on the isotope separation of LLFPs were begun for Se-79, Sn-126 and (CS)-C-135. (C) 2007 Elsevier Ltd. All rights reserved.