Separation of Th, U, Pa, Ra and Ac from natural uranium and thorium series

The behavior of radium on ion exchange resins (DOWEX 1X8 and DOWEX 50 WX8) in different acidic media (HCl, HNO3, HClO4) and of thorium on the anion exchange resin DOWEX 1X8 in HCl medium has been investigated and the distribution coefficients K-d determined. On the basis of these data and those from the literature, three ways for the separation of Th, Pa and Ac from natural thorium series have been proposed; in the first step, Th was adsorbed on the anion exchange resin with HNO3 as a solvent, in the second step Ac and Pa were separated on the cation exchange resin using HCl, HNO3 and HClO4. The separation of U, Th, Pa and Ra from the natural uranium series (4n+2) was carried out as follows: U and Pa were adsorbed on the anion exchange resin in HCl medium; after 2 days Pa-234 had decayed and U was eluted. Th and Pa were separated on the cation exchange resin in HNO3, since Th was adsorbed and Ra was eluted. After 24 h, Pa-234 can be generated and eluted. (C) 1999 Elsevier Science Ltd. All rights reserved.