More specifically, the invention concerns a method using at least one crown compound, either to recover the final traces of plutonium in aqueous solutions polluted by salts of this metal, for example concentrated solutions of fission products derived from the reprocessing of irradiated fuels and the effluents from reprocessing installations, or to separate the plutonium from americium from concentrated solutions of plutonium.
For several years, the most widely used technique to reprocess irradiated nuclear fuels consists of dissolving the fuel in a nitric solution and of then placing the nitric solution obtained in contact with an organic solvent so as to extract from the latter the uranium and the plutonium and to separate them from most of the fission products which remain in the aqueous solution; this aqueous solution corresponds to a concentrated fission product solution, but it generally contains traces of plutonium which need to be recovered. Similarly, at the end of processing, aqueous effluents are also recovered containing traces of plutonium which need to be recovered.
Currently known methods to carry out this type of processing result in obtaining satisfactory results, but it is still advantageous to further improve the plutonium decontamination percentage of all these solutions.
Another problem concerning the decontamination and purification of plutonium exists in the case of concentrated plutonium solutions which, when ageing, are found to be contaminated by plutonium offspring, such as americium, which need to be separated.