Experience with aluminum perrhenate targets for reactor production of high specific activity Re-186

Abstract

An alternative method for the production of multicurie quantities of (n, gamma) Re-186 has been investigated utilizing irradiation of sub-milligram-sized targets of water-soluble, Re-185-enriched aluminum perrhenate in high neutron fluxes (∼4 × 10 14 cm 2 s −1) for up to 2 weeks. These targets can be accurately aliquoted from solution and dried in quartz vials prior to irradiation, immobilizing them and preventing their dispersal upon opening. Aluminum functions as an excellent counterion because of its high valence and because it forms only short-lived radioactivities under neutron bombardment. Approximately 190, multi-curie-sized Re-186 targets have been irradiated and processed, recovering typically ∼85% of the Re-186 activity in 0.5 ml water and employing only glove box techniques. This product exhibits >98% of the radiorhenium in the chemical form of perrhenate ion by ITLC and has a specific activity of about 3 Ci/mg Re. Similar experience has been obtained using Re-187-enriched aluminum perrhenate for the production of Re-188. Aluminum perrhenate is thus a suitable target for a high flux reactor, permitting easy recovery of rhenium activities in suitable chemical form in an oxidant-free, neutral aqueous solution which is practical for development of radiopharmaceutical kits for new applications. In addition, the short processing time and simple manipulations required by this target contribute to radiation safety.