Basic study on decontamination of TRU wastes with cerium mediated electrolytic oxidation method
Ishii, Junichi; Kobayashi, Fuyumi ; Uchida, Shoji; Sumiya, Masato; Kida, Takashi; Shirahashi, Koichi ; Umeda, Miki ; Sakuraba, Koichi
At Nuclear Fuel Cycle Safety Engineering Research Facility, the cerium mediated electrolytic oxidation method which is a decontamination technique to decrease the radioactivity of TRU wastes to the clearance-level has been developed for the effective reduction of TRU wastes generated from the decommissioning of a nuclear fuel reprocessing facility and so on. This method corrodes the oxide layer and the surface of metallic TRU metal wastes by the strong oxidation power of Ce in nitric acid. In this study, parameter tests were conducted to optimize the solution condition of Ce initial concentrations and nitric acid concentrations. The target corrosion rate of metallic TRU wastes set to be 24m/h for the practical use of this method. Under the optimized solution condition, a dissolution test of stainless steel simulating wastes was carried out. From the result of the dissolution test, the average corrosion rate was 3.3 m/h during the test time of 90 hours. Based on the supposition that the corrosion depth of metallic TRU wastes was 20 m enough to achieve the clearance-level, the treatment time for the decontamination was about 6 hours. It was confirmed from the result that the decontamination could be performed within one day and the decontamination solution could repeatedly reuse 15 times.