Effect of Pulse Electrolysis on Morphology of Co-Deposited MOX Granules

In the oxide electrowinning method of nuclear fuel recycling, the applicability of the pulse electrolysis method to the mixed-oxide (MOX) codeposition process was evaluated. Several experiments were conducted involving uranium, plutonium, and elements simulating fission products (FPs) or corrosion products (CPs). Through these experiments, the effects of impurities and electrolysis pulse waveforms on the deposit were clarified. In particular, the difference between the dissolution kinetics of UO2 and PuO2 during the period in which current was stopped was found to be the most important factor influencing the deposition behaviors. As a result, pulse electrolysis conditions, which could restrain Pu enrichment of the deposited MOX, were confirmed. Furthermore, it was found that the elemental distribution in the MOX granule obtained by pulse electrolysis was homogenized, which is well suited for nuclear fuel fabrication. Finally, a qualitative model of the pulse electrolysis reaction near the field of the cathode surface is proposed.