Fabrication of 'JOYO' fuel, (3)

The operation by wet-process has been started for the recovery and refinement of plutonium from the scraps containing high degree of impurities. This paper presents a part of the results of the operation. The wet-recovery process consists of the combination of anion exchange and precipitation processes. For the sake of criticality safety, the ''dimension control system'' is adopted in the process. The flow sheet of the whole process is presented. To increase the decontamination factor, the plutonium nitrate solution is precipitated with oxalic acids to produce plutonium oxalate which is finally converted into plutonium dioxide by means of drying and calcination. The result of operation indicates that the U/Pu ratio of the refined PuO2 powder is less than 1%. Other results of impurity analysis are shown in a table, indicating that the powder is pure enough to satisfy the specification of JOYO fuel pellets. The material balance is also presented in a table. The characteristics of the recovered powder were also investigated. Especially, the relations between the specific surface area and the calcination temperature and time were investigated. Two figures are provided to show these relations. (Aoki, K.)