Abstract: An ultrasonic wave cerium(Ⅳ) decontamination technology for stainless steel wastes produced in decommissioning process of nuclear facilities has been investigated. Using an orthogonal experiment method, the effects on corrosion weight loss rate and decontamination factor of stainless steel have been studied in different conditions, including concentrations of HNO₃ and Ce(NH₄)₂(NO₃)₆, temperature of solution, and ultrasonic time. Results showed that temperature and Ce(NH₄)₂(NO₃)₆ concentration would be the major influence factors. A maximum corrosion rate of 8.07 μm/h was obtained with the optimal parameters of Ce(NH₄)₂(NO₃)₆ (0.15 mol/L), HNO₃ (1.0 mol/L) and 85 ℃ for the decontamination process. The corrosion behavior of coupons was observed by a scanning electron microscope (SEM), and the results showed that cavitation corrosion was caused by ultrasonic wave occurred on the surface of a decontaminated coupon. A decontamination experiment for a section of spent fuels storage tube for demonstration was conducted, and a decontamination factor of 158.8 was achieved.

Key words: cavitation effect, cerium (Ⅳ), orthogonal experiment, corrosion rate, decontamination factor, electrochemical oxidation