蒙特卡洛法模拟玻璃固化体浸出行为的研究

发布时间：2018-12-18 00:09

【摘要】：高放废物的处置关系到人类的健康和环境的安全,因而引起国际上广泛的重视。目前最理想的方案为:将高放废物玻璃固化处理,然后进行深层地质处置。然而在长期的地质处置过程中,玻璃固化体会受到地下水的侵蚀,发生化学反应并溶解,导致放射性核素的浸出,威胁到生物圈的安全。因此,研究高放废物玻璃固化体在水中的溶解行为,对高放废物深层地质处置有重大意义。本文首先综述了高放废物玻璃固化体溶解行为模型的研究现状,从这些模型的基本原理出发,对它们在高放废物玻璃固化体溶解行为方面的应用进行了详细的论述,对它们的优缺点进行了评价,分析了各种模型的适用对象和发展前景。在实验研究中,使用固定成分的玻璃固化体配方,采用MCC-1静态浸出实验,研究了玻璃固化体在去离子水中长期的溶解行为。并通过XRD、FTIR、ICP等测试手段进行分析。实验结果表明:玻璃固化体在长期的浸泡过程中,硅、硼和铝的浓度都能达到一定的平衡,且达到平衡的时间分别为150天、180天和210天,其平衡浓度值分别为为21.5ug/m L、2.5ug/m L和6.5 ug/m L。在浸泡过程中玻璃固化体表面无析晶现象,受侵蚀后的玻璃固化体表面产物为无定型结构,玻璃固化体内部主要结构单元未发生明显变化。同时根据玻璃固化体在水中的侵蚀机理,开发了简单的蒙特卡洛模型,并运用该模型模拟了玻璃固化体在去离子水中的溶解行为。模拟结果显示:随着反应的进行,去离子水中硅的浓度会达到一个平衡状态。这是由硅的溶解和析出的概率值所决定,在硅的溶解析出动力学反应过程中,玻璃固化体与水的接触面会形成由硅组成的胶体层,对硼和铝的浸出产生了阻碍效应。通过限制硼和铝的浓度,最后各种成分的浓度都达到平衡状态。实验结果与模拟计算结果较为吻合。此外,我们在钠硼硅三组分模型的基础上引入了铝原子,用新的反应参数来描述铝原子的特征,进一步验证了该模型的可靠性。
[Abstract]:The disposal of HLW is related to human health and environmental safety. The ideal solution is to solidify high-level waste glass and then treat it in deep geology. However, in the long-term geological disposal process, the glass curing experience is eroded by groundwater, chemical reaction occurs and dissolved, which leads to the leaching of radionuclides and threatens the safety of the biosphere. Therefore, it is of great significance to study the dissolution behavior of glass solidification in water for deep geological disposal of high-level radioactive waste. In this paper, the current research status of glass solidification behavior models of high level radioactive waste is reviewed. Based on the basic principles of these models, the application of these models to the dissolution behavior of glass solidification is discussed in detail. Their advantages and disadvantages are evaluated, and the applicable objects and development prospects of various models are analyzed. In the experimental study, the dissolution behavior of the glass solidified in deionized water for a long time was studied by using the fixed composition of glass solidification formula and MCC-1 static leaching experiment. And through XRD,FTIR,ICP and other testing means to analyze. The experimental results show that the concentration of silicon, boron and aluminum can reach a certain equilibrium in the process of soaking for a long time, and the equilibrium time is 150 days, 180 days and 210 days, respectively, and the equilibrium concentration is 21.5ug/m L. 2.5ug/m L and 6.5 ug/m L. In the process of soaking, there is no crystallization on the surface of the glass solidified body. The surface product of the glass solidified body after erosion is amorphous structure, and the main structural units of the glass solidified body have not changed obviously. A simple Monte Carlo model was developed according to the erosion mechanism of glass solidified in water. The dissolution behavior of glass solidified in deionized water was simulated by using the model. The simulation results show that the concentration of silicon in deionized water reaches a equilibrium state with the reaction. This is determined by the probability value of dissolution and precipitation of silicon. During the kinetic reaction of dissolution and precipitation of silicon, the interface between glass solidified body and water will form a colloidal layer composed of silicon, which will hinder the leaching of boron and aluminum. By limiting the concentration of boron and aluminum, the concentration of each component reaches equilibrium. The experimental results are in good agreement with the simulation results. In addition, on the basis of the three-component model of sodium boron and silicon, the aluminum atom is introduced, and the new reaction parameters are used to describe the characteristics of the aluminum atom, which further verifies the reliability of the model.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ171.1

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