【作者】 张华；

【导师】 罗上庚；

【作者基本信息】 中国原子能科学研究院 ， 核燃料循环与材料， 2004， 博士

【摘要】 高放废物固化体的安全处置，对保护生态环境和核能可持续发展具有重要意义。本工作研究模拟低氧地质处置条件下的玻璃固化体的浸出行为，对浸出后样品作了分析测定；采用地球化学模型和蒙特卡罗法作了模拟玻璃固化体的浸出行为研究；并用自蔓延高温合成法包容锶，对固化体的性能作了测定。 本文采用静态浸出实验研究高放废液玻璃固化体在低氧模拟地质处置条件下的浸出行为。浸出液分析结果表明，不论是玻璃固化体质量损失率，还是单一元素（B、Na、Si、Al和其它元素）的浸出率都先呈指数递减规律变化，达到平衡后，低氧条件的浸出率比大气体系中的浸出率低，达到(10^-4～10^-5（g／cm²·d）)，表明低氧条件减缓玻璃固化体的腐蚀速率。X射线衍射分析和扫描电镜测定表明，90℃条件下玻璃固化体表面没有明显的衍射峰；150℃条件下，182天后玻璃表面有微弱的衍射峰出现。X-射线能谱分析表明是Ca-Si-Al-Fe-（P）氧化物的混合物晶粒。玻璃固化体在150℃和90℃条件下的浸出不属于单纯离子扩散或网络溶解控制过程，而是两者或者更多因素共同控制的过程。玻璃体中主要元素Si在90℃和150℃条件下的浸出，也是离子扩散和网络溶解两者或更多因素共同控制的过程。Na和B元素在90℃条件下浸出属于离子扩散控制过程。 本文对玻璃固化体和富烧绿石型人造岩石在多种地质处置介质条件下的浸出行为进行了研究。样品质量损失率分析显示，富烧绿石样品在五种模拟地质介质中仍保持较低的浸出率，显现良好化学稳定性。花岗岩+Fe₃O₄和膨润土+Fe₃O₄两种模拟介质对固化体浸出率的影响大于其他三种介质的浸出率，在这两种地质介质中，固化体样品的浸出率在开始半年内比它在其他介质中的浸出率明显偏高。矿相分析和表面形貌观察表明，Fe₃O₄介质有加速固化体样品腐蚀的作用。X-射线能谱分析结果表明，U和Ba元素在固化体表面略有富集，Ca和Ti元素在固化体表面略有贫化，而Al和Zr元素在固化体表面的含量基本没有变化。玻璃固化体样品分析吃，中国原子能科学研究院博士学位论文结果显示，膨润土体系有增加玻璃腐蚀的倾向。X一射线能谱分析表明，在玻璃样品表面ca、Fe和Al元素呈富集，si和Mg元素略有浸出，Na元素基本完全浸出，这同其他浸出实验结果一致。 本文采用地球化学模型PHREEQC（version2.7）对玻璃固化体在低氧、温度为150℃和90℃、浸出剂分别为去离子水和模拟地下水的四种实验条件下的浸出体系进行了研究。计算了浸出液中主要元素的浓度和沉积相的生成，并将计算结果同实验结果进行了比较。比较结果显示，计算得出的浸出液元素浓度同实验数据十分接近，计算生成的沉积相的成分同分析结果较为一致。表明浸出液达到平衡后，溶液中浸出元素的浓度不仅同浸出剂中离子浓度相关，而且同生成的沉积相密切相关。采用PHREEQC模型，从溶液化学平衡的角度，较好地对玻璃固化体浸出液浓度和沉积相生成进行计算，提供了研究玻璃固化体浸出行为的有效工具。 本文用蒙特卡罗法，设计了模拟玻璃固化体在水溶液中浸出行为的计算模型。采用这一模型对玻璃固化体的浸出行为进行了模拟计算，得出了玻璃固化体的腐蚀深度。这一计算结果同实验结果比较，前14天有较好一致性。研究了不同510:含量五种玻璃固化体的浸出行为，显示5102含量越多，玻璃固化体的耐腐蚀性越好。还研究了不同离子交换几率对玻璃固化体浸出行为的影响。结果说明，当离子交换几率低于逆向反应几率时，玻璃固化体的腐蚀程度降低;当离子交换几率高于逆向反应几率时，玻璃固化体腐蚀加快。蒙特卡罗法从微观角度上研究玻璃固化体的浸出行为，对玻璃固化体的浸出机理研究提供有价值的方法。 本文对自蔓延高温合成法固化放射性废物进行了初步探讨。研究了自蔓延高温合成法固化Sr，对得到的固化体进行矿相分析，物理性质（硬度、孔隙率、密度等）和浸出率测定，研究了该种方法对腮的最大包容率。研究结果显示，自蔓延高温法可以较好的包容放射性废物Sr，最大包容量可达到35wt%。固化体的物理性质和化学性质都较好满足固化放射性废物的要求，表明自蔓延高温法是一种有前途的固化放射性废物的方法。 本研究所作的高放废液玻璃固化体在模拟地质处置条件下（低氧条件和多种地质介质）的浸出行为研究，采用了低氧条件和多种模拟地质介质，包括北山预选厂呱，中国原子能科学研究院博士学位论文址的花岗岩、膨润土、水泥和Fe304（容器腐蚀产物）作为浸出介质，模拟地下水和去离子水作为浸出剂，90℃和巧0℃两种浸出温度;采用了地球化学模型PHREEQC（version2.7）研究玻璃固化体浸出液中主要元素的浓度以及沉积相的生成;采用蒙特卡罗法建立玻璃固化体的计算模型，对玻璃固化体的浸出行为进行研究;采用了自蔓延高温法固化铭，这些工作都是当前国际上比较前沿的研究课题，采用了先进的分析测试技术，并且作了大量计算，得出了理论上和实践上有意义的结果。关键词:高放废液，玻璃固化体，富烧绿石，人造岩石，地质处置，地球化学模型，蒙特卡罗法，自蔓延高温法，钙钦矿更多还原

【Abstract】 It is a very important thing to protect environment and have a sustained development of nuclear industry to safely dispose high-level radioactive waste. This paper studies on several sections, including the leaching test of simulated HLW-glass under low oxygen repository conditions, analyzing leached glass specimens, studing the glass leaching behavior using geochemistry model and Monte Carlo method, immobilizing Sr with SHS and characterising its products.The leaching behaviors of HLW-glass under repository condition-low oxgen were systemically studied. According to MCC-1 method, the fabricated HLW-glass specimens were leached in static condition for 546d. The compositions of leachate were analyzed by ICP-MS and ICP-AES, and the results showed that the leaching rate and mass loss rate were lower than that at atmosphere, and indicted that glass had less corrosion under low oxgen condition. The leached surfaces were detected by XRD and SEM/XEDS. The results showed no diffraction peak appeared on the surface under 90℃; During the same leaching time, there were some little diffraction peaks appeared on the glass under 150℃ after leaching 182d, which may formed the compound of Ca-Si-Al-Fe-(P), Some expressions are emploied to explain the leaching mechanism. The glass dissolution process and leaching behavior of Si element were controlled by both of ion-diffusion reaction and glass-net dissolution reaction, or more others; the leaching behaviors of Na and B element were controlled by ion-diffusion reactions under 90℃ . The leaching behavior of HLW-glass and pyrochlore-rich synroc under multi-barrier media was respectively studied. The results of mass loss rate showed that pyrochlore-rich synroc had a low mass loss rate with better durability. Especially, the barrier media-granite + Fe3O4 and bentonite + Fe3O4, had more effection on the mass loss rate than others in the first half year. The results of XEDS suggested that U and Ba were enriched on the surface;at the same time, Ca and Ti had a little depleted on the surface ofpyrochlore-rich synroc; the results of XRD and SEM indicated that Fe3O4 can increase the corrosion of glass and pyrochlore-rich synroc; The results of glass mass loss rate showed that bentonite had the most corrosive to the glass specimens among barrier media; the results of XEDS indicated that Ca Fe and Al element were enriched on the glass surfaces, Si and Mg had slightly depleted, and Na was completely depleted.The geochemical model, PHREEQC (2.7 version), was used for calculating the leachate compositions and the sediment phases formed on the glass surface. The results showed that the calculating results were well agreed with the experiment results. The calculating results of the sediment phases were consistent to analysed one. All of these results suggested that the geochemical model-PHREEQC could be a good tool to study the leaching behavior of glass under repository conditions. And the results also suggested that the equilibrium in leaching system was based on the interaction among three parts: the glass, the solution and the sediment phases.A Monte-Carlo model was established based on one component-SiO2 and used for calculation of corrosive depth of glass with different content of SiO2. The study indicted that the more content of SiO2 caused the less corrosion on the glass. The effection of different stochastic value of ion exchange reaction was also investigated. And the results showed, when the stochastic value of ion exchange was lower than that of invert reaction, the glass had less corrosion. On the other hand, the calculating results of the corrosion depth were consistent with the experimental results during 14d, which suggested the Monte Carlo model was suitable for studying the glass corrosion depth during that period. The Monte-Carlo model presented an effective tool to leaching mechanism of HLW glass form.The high-temperature (combustion) self-propagating synthesis (SHS) was used for immobilization of Sr element in perovskite synroc. The preliminary study indicated that the SHS-syn更多还原