Process for preventing the extraction of technetium and/or rhenium, particularly during the extraction of uranium and/or plutonium by an organic solvent

A process for the extraction of at least one first element selected from the group consisting of actinides and present in an aqueous solution containing both said first element, at least one second element selected from the group consisting of rhenium and technetium and at least one third element selected from the group consisting of hafnium and zirconium, said process comprising the steps of bringing the aqueous solution into contact with an organic solvent comprising a phosphorous compound having only one electron donor oxygen atom and able to extract said first element, in order to prevent the extraction of the second element with the said first element, adding to the aqueous solution a complexing agent of the third element in a quantity adequate for completely complexing said third element, said agent being soluble in the aqueous solution.