Production of high specific activity 27Mg by fast neutron irradiation and recoil-aided leaching

Abstract

High specific activity 27Mg was produced via recoil-aided leaching from alumina in aqueous medium during irradiation with fast neutrons from a nuclear reactor. After irradiation the aqueous medium was passed through an IC-chelate column, the 24Na formed during irradiation was removed by elution with 0.25 ml · l-1 sodium acetate and subsequently the 27Mg was eluted with 2 mol · l-1 hydrochloric acid. Irradiation of alumina with a particle size of 3 μm and a specific surface area of 100 m2 · g-1 in Milli-Q Plus Water yielded 90% of the total 27Mg activity produced. Under standard conditions activities of about 8 · 105 Bq and specific activities of ca. 1013 Bq · mol-1 were obtained at the end of irradiation. The standard working conditions involved irradiation of 200 mg alumina dispersed in 0.5 ml liquid in a fast neutron flux of 3 · 1015 m-2 · s-1 for 15 min, a waiting time of 10 min, and a processing time of 15 minutes. Various alumina samples with different particle sizes and specific surfaces were tested, and the 27Mg yields were fitted to a mathematical function. Since the high leaching yields cannot only be explained by recoil only, other phenomena such as diffusion and leaching aided by the high hydration energy of the Mg2+ ion are probably involved.