抄録
Economical and efficient decontamination techniques should be developed for various radioactive wastes arising from decommissioning, considering such viewpoints as safety, reduction of disposal cost, effective usage, etc. The decontamination approach using the molten salt electrolytic technique was carried out for contaminated metals such as stainless steel (SUS304), sintered stainless steel, aluminium, and Monel alloy, generated from the decommissioning of the uranium refining and conversion facility. Stainless steel or Monel alloy that had a smooth surface could be decontaminated down to 0.3 Bq/g, the temporary clearance level, by the molten salt electrolytic technique. Intricate shape materials such as pipes, angle materials, and valves could attain the clearance level by cutting the insulating parts. The decontamination efficiency is independent of the electrolytic current density, and the direction of the decontamination object (anode) facing the cathode. However, the application of this technique encounterd difficulty for the decontamination of sintered stainless steel or aluminium, whose surface absorbed uranium in the salt easily. Judging from the result of this experiment, it is feasible to adopt the molten salt electrolytic technique for the decontamination of contaminated metals. As for the practical application of the decontamination system, further studies into its related techniques are required.
