Process for reprocessing spent nuclear fuel not requiring a plutonium-reducing stripping operation

摘要

The invention relates to a process for reprocessing spent nuclear fuel which, among other advantages, does not require a plutonium-reducing stripping operation.;This process finds particular application in the processing of uranium oxide fuels and uranium and plutonium mixed oxide fuels.

主权项

1. A process for reprocessing spent nuclear fuel which comprises:
a) decontaminating uranium and plutonium present in a first nitric acid aqueous phase, resulting from a dissolution of the nuclear fuel in nitric acid, from americium, curium and a major portion of fission products that are also present in the first nitric acid aqueous phase, which decontaminating comprises co-extracting the uranium in oxidation state VI and the plutonium in oxidation state IV in a first organic phase non-miscible with water and comprising a first extractant which is more capable of extracting uranium(VI) and plutonium(IV) than actinides(III) and fission products from the first nitric acid aqueous phase; b) co-stripping, in a second nitric acid aqueous phase, the uranium and the plutonium co-extracted at a), the uranium being stripped in oxidation state VI and the plutonium being stripped in oxidation states IV and VI due to a formation, during the co-stripping, of plutonium(VI) by dismutation of plutonium(IV); c) partitioning the uranium and the plutonium present in the second nitric acid aqueous phase from b) into a first aqueous solution comprising either plutonium without uranium or a mixture of uranium and plutonium, and a second aqueous solution comprising uranium without plutonium, which partitioning comprises:
selectively extracting all or part of the uranium(VI) present in the second nitric acid aqueous phase from b) in a second organic phase non-miscible with water and comprising a second extractant which is different from the first extractant and which is more capable of extracting uranium(VI) than plutonium(IV) from the second nitric acid aqueous phase, which extracting is performed after and/or jointly with a reduction of the plutonium(VI) present in the second nitric acid aqueous phase from b) to plutonium(IV); andstripping, in a third nitric acid aqueous phase, the uranium(VI) thus extracted and thereby obtaining the second aqueous solution comprising uranium without plutonium; and d) purifying the plutonium or the mixture of uranium and plutonium present in the second nitric acid aqueous phase from c) to remove any fission products which may still be present in the second nitric acid aqueous phase.