Porous UO₂sintered pellets and method for fabricating porous UO₂sintered pellets and electrolytic reduction using same

摘要

A method for fabricating porous UO2 sintered pellets to be fed into the electrolytic reduction process for the purpose of metallic nuclear fuel recovery is provided, which includes forming a powder containing U3O8 by oxidizing spent nuclear fuel containing uranium dioxide (UO2) (step 1), fabricating green pellets by compacting the powder formed in step 1 (step 2), fabricating UO2+x sintered pellets by sintering the porous U3O8 green pellets fabricated in step 2 at 1200 to 1600° C., in an atmospheric gas (step 3), and forming UO2 sintered pellets by cooling the UO2+x sintered pellets to room temperature, and reduction the same at 1000 to 1400° C., in a reducing atmosphere (step 4).

主权项

1. A method for fabricating porous UO2 sintered pellets to be fed into an electrolytic reduction process for the purpose of metallic nuclear fuel recovery, comprising the following steps of:
forming a powder containing U3O8 by oxidizing a spent nuclear fuel containing uranium dioxide (UO2) (step 1); fabricating U3O8 green pellets by compacting the powder formed in step 1 (step 2); fabricating UO2+x sintered pellets by sintering the porous U3O8 green pellets fabricated in step 2 at 1200 to 1600° C., in a non-reducing atmospheric gas in a sintering step (step 3); and forming UO2 sintered pellets by cooling the UO2+x sintered pellets in step 3 to room temperature, and reducing the same at 1000 to 1400° C., in a reducing atmosphere in a reducing step (step 4), the reduction of UO2+x sintered pellets being performed independently of step 3, such that the sintering step (step 3) is discontinued before the reducing step (step 4), the temperature of reduction (step 4) being controlled independently of the temperature of sintering (step 3), such that the UO2 sintered pellets formed at the end of the reducing step (step 4) have a O/U ratio of 2.00.