放射性废盐的真空蒸馏净化技术研究

Study on vacuum distillation purification technology for radioactive waste salt

为了降低钚熔盐电解过程中产生的放射性废盐量,减轻后续放射性废物处理处置过程中的压力,采用NaCl-KCl-CeO_(2)混合熔盐作为非放模拟料,对真空蒸馏技术进行了研究。考察了CeO_(2)浓度、温度和压力对蒸馏结果的影响。研究结果表明:在CeO_(2)质量分数为5%~15%、温度为825~925℃、压力为0.1~66 Pa条件下,Ce的净化系数均可达到103以上,获得的馏分盐和残余物CeO_(2)的纯度与混熔前相当,熔盐和CeO_(2)的回收率均稳定在98%以上。蒸馏后NaCl-KCl熔盐组分配比不变,可以在熔盐电解中重复利用。真空蒸馏净化技术在模拟料实验中体现出的良好效果,为后续放射性废盐处理提供了备选路线。

In order to reduce the amount of radioactive waste salt generated in the process of molten salt electrolysis of plutonium and relieve the stress in the subsequent process of treatment and disposal of radioactive waste,the vacuum distillation technology was studied by using NaCl-KCl-CeO_(2) mixed molten salt as simulative material.The effects of CeO_(2) concentration,temperature and pressure on the experiment results were investigated.The results showed that in the range of CeO_(2) mass fraction of 5%~15%,temperature of 825~925℃ and pressure of 0.1~66 Pa,the purification coefficient of Ce could reach above 103,the purity of distillate salt and residual CeO_(2) was equal to that before the mixed melting,and the recovery of molten salt and CeO_(2) was stable above 98%.After distillation,the distribution ratio of NaCl-KCl molten salt remained unchanged and could be reused in molten salt electrolysis.The good performance of vacuum distillation purification technology in simulated material experiments provided an alternative route for subsequent radioactive waste salt treatment.