铝热剂SHS合成污染土壤固化产物中模拟核素的分布

以稀土元素Ce,Er和碱土金属元素Sr作为模拟核素,通过合金固溶度理论分析,并借助于ICP/MS,X射线荧光光谱分析、X射线衍射分析和PCT浸出法等分析手段,研究了对采用铝热剂自蔓延高温合成污染土壤固化产物中模拟核素的分布情况、固化体的物相组成和化学稳定性。结果表明,在SHS高温合成条件下,模拟核素在铁中的含量均在1×10-6数量级以上;示踪核素Ce主要是以CeAl11O18和Ce2SiO5的矿物晶体的形态存在于固化产物中,固化体中模拟核素的28 d平均浸出速率为1×10-5～1×10-6g.m-.2d-1,比一般硼硅酸盐玻璃固化体中稀土元素的浸出速率低1～2个量级;固化体中Ca,Si和Al的28 d浸出速率约为1×10-3g.m-.2d-1,Fe约为1×10-4g.m-.2d-1。放射性核素被固结在固化体中,而不进入到铁中,有利于后续固化体处理的安全性。

Distributing Characteristic of Simulated Nuclide in Contaminated Soil Forming Immobilization with Thermit by Self-Propagating High Temperature Synthesis

Using lanthanide Ce,Er and alkaline earth metals Sr as simulated nuclides,the distributing characteristic of simulated nuclides,phase compositions and chemical durability of contaminated soil were tested by the theory on solid solubility,X-ray diffraction,X-ray fluorescence analysis,ICP-MS and the leaching method.The results showed that in the self-propagating high-temperature synthesis condition,the content at 1×10-6 order of magnitude in Fe,the simulated nuclide Ce mainly formed crystalline phase CeAl11O18 and Ce2SiO5.The normalized release rate of simulated nuclides during 28 d was 1×10-5~1×10-6 g · m-2 · d-1,which was much lower than the borosilicate glass solid form.The normalized release rate of Ca,Si and Al during 28 d was 1×10-3 g · m-2 · d-1,and that of Fe was 1×10-4 g · m-2 · d-1.Radionuclide was solidified in condense but not into Fe,insure safely dispose high-level radioactive waste.