Journal of Nuclear Fuel Cycle and Waste Technology

This study was performed to evaluate the co- and sequential separation of Tc, Np and U from the simulated multi-component HLW solution by a TBP (tributyl phosphate)-TOA (tri- octyl amine)/NDD (n-dodecane)-HNO3 extraction system. An optimal condition of (30 % TBP- 0.5 % TOA)/NDD-1 M HNO3 was selected by taking account of a prevention of the 3rd phase and effects of concentration of TBP, TOA and nitric acid on the co-extraction of Tc, Np and U. In that condition, the extraction yields were 81 % (Tc), 85 % (Np), less than 9 % (Am and RE elements), about 8 % (Pd), and less than 5 % (other elements) so that the system developed for the co-extraction of Tc, Np and U was proved to be available. For that, however, more than 99 % of Zr was found to be pre-removed. The co-extracted Tc, Np and U were sequentially separated in order of Tc (stripping agent : 5 M HNO3) → Np by reductive stripping (reductive-stripping agent : 0.1 M AHA) → U (stripping agent : 0.01 M HNO3), and then their separation factors were evaluated. At these conditions, 95 % of Tc, 98 %of Np and 99 % of U could be recovered in each step.

Keywords

Tc,Np,U,TBP,TOA,Solvent extraction,REDOX,Selective stripping