Journal of Nuclear Fuel Cycle and Waste Technology

The reductive stripping of Np using a n-butyraldehyde (NBA) from loaded organic solution containing Np, which was oxidative-extracted in a system of a 30 % TBP/NDD-2M HNO3 and O/A=2 containing 0.005 M K2Cr2O7 as an oxidant of Np, was studied. The stripping yields of Np was increased with an increasing the NBA concentration, with a decreasing the nitric acid concentration of stripping solution and with a decreasing the reaction temperature. The apparent reductive stripping rate equation was shown by the following equation : -d [Np]Org./dt = 1,524 exp(-2,906/T) [NBA]0.91 [H+]-0.92 [Np]Org. At 1.04 M NBA and 2 M HNO3, the stripping yield of Np and U was 70.1 %, and 7.1 %, respectively, and the separation factor of U over Np (=DU/DNp) was about 30.4. Therefore, it was found that U and Np co-extracted in a system of TBP-HNO3 could be effectively mutual-separated by the NBA.

Keywords

Neptunium,TBP,NBA,Extraction/stripping,Oxidation/Reduction,Kinetics,Np