模拟核素固化体Gd_2Zr_(2-x)Ce_xO7(0≤x≤2.0)的物相及化学稳定性研究  

Phase and chemical stability of simulated waste forms Gd_2Zr_(2-x)Ce_xO_7(0≤x≤2.0)

作　　者：卢喜瑞[1,2] 董发勤[2] 胡淞[2] 王晓丽[3] 吴彦霖 

机构地区：[1]四川大学原子核科学技术研究所,成都610064 [2]西南科技大学核废物与环境安全国防重点学科实验室,绵阳621010 [3]中国工程物理研究院核物理与化学研究所,绵阳621900 [4]日本国立综合研究大学院大学

出　　处：《物理学报》2012年第15期121-128,共8页Acta Physica Sinica

基　　金：国家高技术研究发展计划(863)计划重点项目(批准号:2009AA050703);国家自然科学基金青年科学基金(批准号:21007052);四川大学辐射物理及技术教育部重点实验室基金(批准号:2011-03);西南科技大学核废物与环境安全国防重点学科实验室基金(批准号:1lzxnk09);西南科技大学青年基金(批准号:1lzx3108)资助的课题~~

摘　　要：为研究钆锆烧绿石固化Pu(Ⅳ)的相变化情况及化学稳定性,以Gd_2O_3,ZrO_2为原料,Ce(Ⅳ)作为Pu(Ⅳ)的模拟替代物质,采用冷压热烧结的方法制备出Gd2Zr_(2-x)Ce_xO_7(0≤x≤2.0)系列样品.分别在40℃和70℃的合成海水中,对固化体的长期浸出性能进行研究.借助粉末X射线衍射仪对所制备样品的物相信息进行收集,利用等离子体质谱仪对固化体的浸出浓度数据进行分析.研究结果表明:当x≤0.08时,固化体保持为烧绿石相;当x>0.08时,固化体转变为具有缺陷的萤石型结构相.固化体中Gd^(3+),Zr^(4+)和Ce^(4+)在合成海水中,随着浸泡时间的延长浸出浓度逐渐上升,70℃下的浸出浓度高于40℃下的浸出浓度.在42 d时,固化体中Gd^(3+)的最大浸出浓度在0.032μg.ml^(-1)以下,Zr^(4+)的最大浸出浓度在0.003μg.ml^(-1)以下;Ce^(4+)的最大浸出浓度在0.032μg.ml^(-1)以下.In order to investigate phase change and chemical stability of pyrochlore Gd2Zr2O7 used for immobilizing Pu（Ⅳ）,tetravalent cerium is used as the simulacrums for plutonium with tetravalence,and Gd2Zr2-xCexO7（0≤x≤2.0） series samples are successfully synthesized by high temperature solid reaction and using Gd2O3 and ZrO2 powders as starting materials.The experiments of long-term chemical stability are conducted in synthetic seawater at 40℃and 70℃separately.The XRD diffractive data and extraction ratio of as-gained samples are collected by the help of X-ray diffraction（XRD） instrument and inductively coupled plasma mass spectrometry. The results indicate that the phases of compounds change from pyrochlore to fluorite-type phase when the value of x is more than 0.08. Extraction ratios of Gd3＋,Zr4＋ and Ce4＋ in waste forms increase with the increase of immersion time in synthetic seawater.The extraction ratio of waste form at 70℃is higher than at 40℃.The highest extraction ratios of Gd3＋,Zr4＋ and Ce4＋ for 42 days are no more than 0.032,0.003 and 0.032μgml-1 respectively.

关 键 词：烧绿石 固化体 物相 化学稳定性 

分 类 号：O571.3[理学—粒子物理与原子核物理]