The development of solid-state materials for the sequestration of nuclear waste

导语：与化石燃料相比，核能的温室气体排放量更低。然而，核电的一个后果是放射性废物。这项研究计划的目标是开发核废料形成材料。目标1：废物形态的低温合成和抗辐射性能：所提出的核废料形态通常是用高温方法合成的；然而，这些方法在大规模合成这些材料时并不实用。基于溶液的方法可以在较低的温度下形成材料。这项研究将确定合成方法是否会影响这些材料的抗辐射能力。由于辐射损伤导致材料从晶态转变为非晶态，可能会影响其性能。采用溶胶凝胶法和共沉淀法合成单相和复相陶瓷。在低温下合成这些材料所需的条件以及合成方法对这些材料的抗辐射性能的影响将被确定。通过离子注入模拟辐射诱导的结构损伤，并用X射线衍射和X射线吸收光谱(XAS)对其进行研究。目标2：多相微晶玻璃复合材料：乏核燃料芯块中含有多种裂变产物和吖系元素。必须找到能够隔离具有不同离子半径和氧化态的元素的材料。微晶玻璃复合材料为这一应用提供了前所未有的灵活性。这项研究的目的是合成含有分散在玻璃基质中的多个陶瓷相的微晶的微晶玻璃-陶瓷复合材料，以增加可隔离的废元素的数量。采用多种方法合成了微晶玻璃复合材料，并用X射线衍射仪、X射线衍射仪和扫描电子显微镜对其进行了研究。目标3：核废料形态的耐腐蚀性：必须了解核废料形态的耐腐蚀性，才能预测这些材料的长期行为。废物形式的组成和结构以及水环境的性质的变化会影响这些材料的腐蚀。这项研究的目的是了解拟议废物形式的耐腐蚀性如何随成分和结构的变化而变化。废旧材料会在不同的条件下暴露在水中。材料将用XAS和XPS进行研究，浸出离子的浓度将用质谱仪进行研究。意义：重要的是要研究长期封存核废料的战略，以支持利用核能应对气候变化。这一独特的研究项目将研究陶瓷和微晶玻璃复合材料的合成、抗辐射和耐腐蚀性。这项研究计划还将培养出在固态化学和核材料方面经验丰富的受过独特培训的HQP。

INTRODUCTION: Nuclear power has lower greenhouse gas emissions compared to fossil fuels. However, a consequence of nuclear power is radioactive waste. The objective of this research program is the development of nuclear waste form materials. OBJECTIVE 1: LOW TEMPERATURE SYNTHESIS AND RADIATION RESISTANCE OF WASTE FORMS: Proposed nuclear waste forms are often synthesized using high-temperature methods; however, these methods are not practical when synthesizing these materials on large scales. Solution-based methods can form materials at lower temperatures. This study will determine if the synthesis method affects the radiation resistance of these materials. The transformation of a material from crystalline to amorphous because of radiation-induced damage could affect its properties. Single- and multi-phase ceramics will be synthesized using sol-gel and coprecipitation methods. The conditions needed to synthesize these materials at low temperatures will be determined along with the effect the synthesis method has on the radiation resistance of these materials. Radiation-induced structural damage will be simulated by ion implantation and studied using XRD and X-ray absorption spectroscopy (XAS). OBJECTIVE 2: MULTI-PHASE GLASS-CERAMIC COMPOSITES: Spent nuclear fuel pellets contain a variety of fission products and actinides. It is essential to find materials that can sequester elements having different ionic radii and oxidation states. Glass-ceramic composites offer unprecedented flexibility for this application. The objective of this study is to synthesize glass-ceramic composites containing crystallites of several ceramic phases dispersed in a glass matrix so as to increase the number of waste elements that can be sequestered. The glass-ceramic composites will be synthesized using multiple methods and studied using XRD, XAS, and SEM. OBJECTIVE 3: CORROSION RESISTANCE OF NUCLEAR WASTE FORMS: The corrosion resistance of nuclear waste forms must be understood to predict the long-term behaviour of these materials. Changes in the composition and structure of the waste form as well as the properties of the aqueous environment can affect the corrosion of these materials. The objective of this study is to understand how the corrosion resistance of proposed waste forms changes depending on composition and structure. Waste form materials will be exposed to water under different conditions. The materials will be studied using XAS and XPS, and the concentration of leached ions will be studied using mass spectrometry. SIGNIFICANCE: It is important to investigate strategies to sequester nuclear waste for the long term to support the use of nuclear energy to combat climate change. This unique research program will study the synthesis, radiation resistance, and corrosion resistance of ceramic and glass-ceramic composite materials. This research program will also lead to uniquely trained HQP who are experienced in solid-state chemistry and nuclear materials.