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

导言：与化石燃料相比，核电的温室气体排放量更低。然而，核能的一个后果是产生放射性废物。这项研究计划的目标是发展核废料形式的材料。目标1：废物形式的低温合成和抗辐射性：拟议的核废料形式通常使用高温方法合成；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。本研究将确定合成方法是否会影响这些材料的抗辐射性能。由于辐射引起的损伤，材料从晶态转变为非晶态会影响材料的性能。将采用溶胶-凝胶法和共沉淀法合成单相和多相陶瓷。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引起的结构损伤，并利用x射线衍射和x射线吸收光谱（XAS）进行研究。目的2：多相玻璃陶瓷复合材料：乏燃料球团含有多种裂变产物和锕系元素。找到能够隔离具有不同离子半径和氧化态的元素的材料是至关重要的。玻璃陶瓷复合材料为这一应用提供了前所未有的灵活性。本研究的目的是合成含有分散在玻璃基体中的多个陶瓷相的微晶的玻璃-陶瓷复合材料，以增加可以隔离的废元素的数量。将采用多种方法合成玻璃陶瓷复合材料，并利用XRD， XAS和SEM对其进行研究。目标3：核废料形式的耐腐蚀性：必须了解核废料形式的耐腐蚀性，以预测这些材料的长期行为。废物形态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。本研究的目的是了解拟议废物形式的耐腐蚀性如何根据组成和结构而变化。废弃物会在不同的条件下暴露在水中。材料将使用XAS和XPS进行研究，并使用质谱法研究浸出离子的浓度。意义：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，具有重要意义。这个独特的研究项目将研究陶瓷和玻璃陶瓷复合材料的合成、耐辐射和耐腐蚀性。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高素质人才。

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.