US 7,731,870 B2 · Purex method and its uses

Abstract

The invention relates to a method constituting an improvement of the PUREX method, which makes it possible to obtain separation of uranium from the other actinides (Pu, Np, Th, . . . ) in a single purification cycle. This method successively comprises: a) co-extracting the uranium(VI), plutonium(IV) and other actinides(IV) or (VI) from an aqueous nitric solution by using solvent phase and scrubbing the latter; b) back-extracting the plutonium in oxidation state (III) from the solvent phase by using an aqueous nitric solution; c) back-extracting the uranium in oxidation state (VI) from the solvent phase by using an aqueous nitric solution; d) concentrating the aqueous nitric solution resulting from step c) with respect to uranium(VI); and it is characterized in that some of the uranium(VI)-concentrated aqueous solution obtained in step d) is used for back-extracting the actinide(IV) or actinides(IV) from the solvent phase during step b) or between steps b) and c). Uses: reprocessing of spent nuclear fuels based on UO2, (U,Pu)O2 or (U,Th)O2 mixed oxide.

Claims24

Dependent claims

A method for reprocessing a spent nuclear fuel, which successively comprises:

a) separating uranium, plutonium and other actinides from fission products present in an aqueous nitric solution obtained by dissolving the fuel in nitric acid, said separation comprising co-extracting uranium(VI), plutonium(IV) and other actinides(IV) or (VI) from said aqueous solution by using a water-immiscible solvent phase comprising at least one extractant in an organic diluent, and then scrubbing the solvent phase with an aqueous nitric solution;
b) back-extracting plutonium in the oxidation state (III) from the solvent phase resulting from step a) by using an aqueous nitric solution which contains a reducing agent capable of reducing plutonium(IV) into plutonium(III);
c) back-extracting uranium(VI) from the solvent phase resulting from step b) by using an aqueous nitric solution;
d) concentrating the aqueous nitric solution resulting from step c) with respect to uranium(VI);
and in which a part of the uranium(VI)-concentrated aqueous solution resulting from step d) is used for further back-extracting during step b) at least one actinide(IV) selected from neptunium(IV) and thorium(IV) from the solvent phase resulting from step a).

2 more elements

A method for reprocessing a spent nuclear fuel, which successively comprises:

a) separating uranium, plutonium and other actinides from fission products present in an aqueous nitric solution obtained by dissolving the fuel in nitric acid, said separation comprising co-extracting uranium(VI), plutonium(IV) and other actinides(IV) or (VI) from said aqueous solution by using a water-immiscible solvent phase comprising at least one extractant in an organic diluent, and then scrubbing the solvent phase with an aqueous nitric solution;
b) back-extracting plutonium in the oxidation state (III) from the solvent phase resulting from step a) by using an aqueous nitric solution which contains a reducing agent capable of reducing plutonium(IV) into plutonium(III);
c) back-extracting uranium(VI) from the solvent phase resulting from step b) by using an aqueous nitric solution;
d) concentrating the aqueous nitric solution resulting from step c) with respect to uranium(VI);
and in which a part of the uranium(VI)-concentrated aqueous solution resulting from step d) is used for back-extracting between steps b) and c) at least one actinide(IV) selected from neptunium(IV), thorium(IV) and plutonium(IV) from the solvent phase resulting from step b).

2 more elements

Dependencies are inferred from the claim text.

Purex method and its uses

Life of this patent

Purex method and its uses

Life of this patent

Abstract

Claims24