锆英石基An4+放射性核素固化体性能研究

为研究锆英石基An4+(四价锕系核素)放射性核素固化体的性能,利用Ce4+作为An4+的模拟替代物质,以ZrO2、SiO2和CeO2粉体为原料,采用高温固相法制备出包容20%(物质的量,下同)Ce4+的锆英石基固化体,利用60Co源γ射线辐照装置对其进行572.1kGy的γ射线辐照.利用粉末X射线衍射仪、扫描电子显微镜和电感耦合等离子体质谱仪对γ射线辐照前后固化体的物相、结构、微观形貌及模拟核素的浸出行为进行了研究.结果表明,固化体中虽包容有20%的Ce4+,但其主物相仍以锆英石物相为主,与标准样品相比晶胞参数发生10-4nm量级的变化,经γ射线辐照后样品晶胞参数仅发生了10-5~10-4nm量级的微弱变化,在pH6.5的HCI浸出液中Ce4+的平衡浓度低于0.30μg/L.

Capability of zircon as radioactive waste forms for immobilizing tetravalent actinides

In order to investigate the capability of zircon as radioactive waste forms for immobilizing tetravalent actinides, tetravalent europium (Ce4+) was used as the simulacrum for tetravalent actinides, the waste forms containing 20% Ce4+ were successfully synthesized by high temperature solid reaction and using ZrO2, SiO2 and CeO2 powders as starting materials. Then, the as-gained samples were irradiated using a 60Co γ-ray source with 572.1kGy doses. The phases, structure, microcosmic shape and leaching yield of synthesized waste forms before and after γ-ray irradiation were characterized by the help of X-ray diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma mass spectrometry (ICP-Mass). The zircon phase was the major phase for the as-gained waste forms although containing 20% Ce4+. The alteration of 10-4 nm magnitude in the crystal cell parameters was measured (cf the standard XRD card of zircon). The crystal cell parameters of samples changed between 10-5 and 10-4nm magnitude before and after irradiation. The equilibrium concentration of Ce4+ in HCI lixivium (pH=6.5) was less than 0.30μg/L.