FLOWSHEET FOR THE RECOVERY AND PURIFICATION OF NI-63

The production of large quantities of high specific activity (> 10 Ci/ g) Ni-63 requires both a highly enriched Ni-62 target and a long irrad iation period at high neutron flux. Trace impurities in the nickel and associated target materials are also activated and account for a sign ificant fraction of the discharged activity, and essentially all of th e gamma activity. While most of these undesirable activation products can be removed as chloride complexes during anion exchange, chromium, present as Cr-51, and scandium, present as Sc-46, are exceptions and r equire additional processing to achieve the desired purity. Scandium i s readily removed during cation exchange, while the removal of chromiu m requires careful control of conditions during solvent extraction wit h tri-n-octylphosphine oxide. Optimized flow-sheets are discussed base d upon the current development and production experience.