THERMOCHROMATOGRAPHIC SEPARATION OF RADIOSELENIUM FROM IRRADIATED CU3AS-TARGET - PRODUCTION OF NO-CARRIER ADDED SE-75

No-carrier added Se-75 (T1/2 = 120 d) was produced with a high-current Cu3As-target via the As-75(p,n)-reaction. A two-step thermochromatogr aphic method using O2 as the purging gas was developed to separate rad ioselenium which was taken up in 6 M HCl. A 4 h irradiation with proto ns (E(p) = 17 --> 0 MeV) at a beam current of 20 muA led to about 37 M Bq (1 mCi) of no-carrier added Se-75. The product was of high radionuc lidic purity and predominantly consisted of 75SeO3(2). After reduction with SO2, the radioactive species was efficiently extracted in benzen e and showed high chemical reactivity. The extraction behaviour of rad ioselenium in benzene was found to be strongly influenced by the arsen ic concentration in the solution.