模拟含An^(4+)放射性石墨的SHS固化处理研究

SHS Technology for Immobilizing Simulated Radioactive Graphite Containing An^(4+)

为研究含An4+放射性石墨的SHS固化处理能力,以C、Al和TiO2为原料,CeO2为An4+模拟物质,利用自行设计的SHS反应装置模拟开展含An4+放射性石墨的固化研究。借助X射线衍射仪对所制备固化体的物相、相关系及固溶度等进行研究,并对样品的XRD数据进行了结构精修。结果表明:在空气气氛中,利用3C+4Al+3TiO2=2Al2O3+3TiC反应进行含An4+放射性废物的SHS固化处理,其固溶度为3%(以质量计,下同)。固溶度为0%～3%的固化体以Al2O3、TiC、C、TiO2和AlN相存在,燃烧产物中Al2O3的晶胞参数a、b和c发生了10-3nm量级变化,V发生了10-3nm3量级变化,α、β和γ发生了(10-3)°～(10-1)°量级变化;产物中TiC的晶胞参数a、b和c发生了10-3nm量级变化,V发生了10-3nm3量级变化,α、β和γ未出现变化。所制备的样品形貌不规则,主要以块状为主,晶粒度主要集中在5～20μm之间。

In order to develop SHS technology for immobilizing radioactive graphite containing An^4＋,CeO2 was used as the simulacrums for An^4＋,the waste forms were synthesized by designed equipment and using C,Al and TiO2 powders as the starting materials.The phase,solubility of An^4＋ and the relationship of phases in waste forms were analyzed by the help of X-ray diffraction（XRD） instrument.Moreover,the crystal cell parameters were calculated by structural refinement method.The results indicate that the solubility of simulacrum in waste forms is 3%（in weight）treating the radioactive wastes containing An^4＋ by the reaction： 3C＋4Al＋3TiO2 = 2Al2O3＋3TiC.The waste forms exist as Al2O3,TiC,C,TiO2 and AlN phase when the contents of CeO2 in the range of solubility.Crystal cell parameters a,b and c in Al2O3 crystal lattices change about 10-3 nm magnitude,the value of V varies about 10-3 nm^3 magnitude,and α,β and γ change from（10^-3）° to（10^-1）° magnitude.The crystal cell parameters a,b,c of TiC in combustion products vary about 10-3nm magnitude,and the volume of crystal cell changes about 10-3 nm^3 magnitude,and α,β and γ are not found changes.The as-gained samples were mostly block-shaped and grain sizes distribute mainly in a range of 5~20 μm.