Carrier-free Separation of Manganese-54 from Iron Targets Irradiated with Fast Neutrons

A combined chemical method was studied for the preparation of high specific activity manganese-54 by pile-neutron irradiation. The commercial pure iron was purified prior to neutron irradiation and manganese-54 was separated from irradiated iron with successive cation and anion exchange techniques as follows. The commercial pure iron was dissolved in hydrochloric acid, and ferric hydroxide was precipitated by the addition of ammonia. The ferric hydroxide precipitate was centrifuged and dissolved in a certain amount of hydrofluoric acid. The precipitation of ferric hydroxide from the hydrofluoric acid solution was repeated until no more chloride ion was detected in the supernatant solution. Several trace metals contained in the commercial pure iron, e.g., cobalt and copper, were eliminated by this procedure as the stable ammine complexes. The final hydroxide precipitate obtained by the reprecipitation was dissolved in IN hydrofluoric acid, and manganese was adsorbed by the cation exchange resin Dowex 50×8. The collected effluent from the cation exchange resin column was evaporated on the water bath to incipient dryness. About 12g of FeF3⋅3H2O was obtained from 5g of the original iron used. About 12g of iron fluoride crystals wrapped with cadmium sheet was irradiated in the TRIGA Mark II Reactor of Rikkyo University (fast neutron flux: 6.5×1010n⋅cm-2⋅sec-1) for 18 hours. After 4 days cooling, the irradiated iron fluoride was dissolved in 1N hydrofluoric acid. Manganese-54 produced by (n, p) reaction from iron-54 and small amount of iron in hydrofluoric acid solution were adsorbed by the cation exchange resin Dowex 50×8. On the other hand, the bulk of iron was separated in the effluent together with arsenic and antimony. Metal ions adsorbed by the cation exchange resin were stripped by 8N hydrochloric acid. Iron in 8N hydrochloric acid solution was adsorbed by the anion exchange resin IRA-400, and manganese-54 was obtained in the effluent as the hydrochloric acid solution. Absolute amount of manganese-54 obtained from 5g of the original iron used was about 0.43μCi.