超声波+四价铈去污技术研究

A study on decontamination technology of ultrasonic wave cerium(Ⅳ)

针对核设施退役过程中产生的不锈钢废物,开展了超声波+四价铈去污技术研究。利用失重法,设计正交实验,研究了硝酸浓度、硝酸铈铵浓度、温度和超声时间对不锈钢的平均腐蚀速率及去污因子的影响。条件实验结果表明:温度、硝酸铈铵浓度为主要影响因素;当硝酸铈铵的浓度为0.15 mol/L,温度为85℃,硝酸浓度为0.1 mol/L时,不锈钢的平均腐蚀速率最高,达到8.07μm/h,引入超声波后将极大提高四价铈去污技术的效率。扫描电镜观测结果表明:去污后的不锈钢表面大部分区域出现了很多蚀孔,表明空化效应强化Ce(IV)去污技术具有强烈的空蚀作用;对乏燃料冷却套管开展了验证去污实验,去污因子达到158.8。

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 tool/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.