通过高温固相反应,以铈作为铀的模拟元素,在1 300℃下保温2h合成了钙钛矿基人造岩石固化体。采用XRD对固化体进行物相分析,同时采用MCC-1静态浸泡法及美国PCT粉末浸泡法对不同铈核素包容量的固化体进行浸出性能研究。结果表明,Ce在钙钛矿人造岩石固化体中的包容量低于质量分数18.94%,约为0.15~0.2个结构单位。Ce元素的掺入起到了促进烧结和稳定钙钛矿晶格的作用,当固化体中Ce的荷载量高达35.04%时,Ca元素的90d浸出浓度已超出检测限而未测得,累积浸出分数低至1.87×10-5 cm;Ce元素的90d浸出率和累积浸出分数低至0.27×10-8cm.d-1和6.55×10-7 cm,比玻璃固化体浸出率低了2~3个数量级,说明钙钛矿固化体具有良好的化学稳定性,且当铈核素掺量接近钙钛矿最大包容量时固化体结构最稳定,抗浸出性能最好。
Using high temperature solid-state method,simulating uranium with cerium,the Ce-doped synroc perovskite has been synthesized at 1 300 ℃ with heat preservation 2 h.The phase composition has been investigated by XRD.Anti-leaching performance has also been researched with MCC-1 and the Product Consistency Test.Results show that synroc perovskite can load cerium less than 18.94%,which is about 15%~20%(mol%) structure unit.The incorporation of Ce has promoted sintering and made the perovskite crystal lattice more stable.While the synroc loads as high as 35.04% weight of cerium,the accumulated leaching fraction of Ca is only 1.87×10-5 cm in 90 days,the leaching rate and accumulated leaching fraction of Ce are only 0.27×10-8 cm·d-1,6.55×10-7 cm in 90 days.The results indicate that the perovskite solidification has excellent chemical durability,and when the dosage of nuclide cerium is close to the saturation capacity of perovskite,the leaching performance is the best.