Abstract: The invention relates to a process for the reextraction in aqueous solution of the plutonium present in an organic solvent, more particularly usable for uranium-plutonium separation.According to this process the organic solvent is contacted with an acid aqueous solution of uranous salt, e.g. uranous nitrate, and hydroxylamine salt, e.g. hydroxylamine nitrate. Under these conditions, the uranous nitrate acts as a reducing agent for plutonium at valency (III and the hydroxylamine nitrate, which is also a plutonium reducing, agent, stabilizes Pu(III) and U(IV) in aqueous phase.Performances comparable to those of the U(IV)-hydrazone nitrate system are obtained without forming prejudicial hydrazine nitrate decomposition products. (FIG. 2).

Abstract: Process for preventing the extraction of technetium and/or rhenium, particularly during the extraction of uranium and/or plutonium by an organic solvent.This process permitting the extraction of a chemical element, such as uranium or plutonium present in an aqueous solution containing both said element, technetium and/or rhenium and zirconium and/or hafnium consists of contacting the aqueous solution with an organic solvent able to extract said element, wherein for preventing the extraction of the technetium and/or rhenium with said element, to the aqueous solution is added a zirconium and/or hafnium complexing agent in a quantity adequate for complexing all the zirconium and/or hafnium, said agent being soluble in the aqueous solution.