Vitrified nuclear waste durability in complex natural environments

了解核废料玻璃在地下的长期耐久性在英国和国际上都很重要，因为许多国家打算在地下地质处置设施中处置玻璃化的放射性废料。为了确保安全处置，我们需要确信放射性元素将保持隔离和固定足够的时间，以使放射性衰变到安全水平。将设置多个屏障(例如金属容器和工程回填)，以延迟地下水到达核废料玻璃，但最终预计会与水接触。虽然目前有许多实验室测试用于确定玻璃在水中的溶解速度，但所有测试都通过增加温度、表面积或两者兼而有之来加速腐蚀，并根据测试条件给出非常不同的预测。实验室测试也是在简化、稳定、无菌的条件下进行的，并使用去离子水，而不考虑不断变化的地球化学条件对玻璃腐蚀率的影响。该奖学金将结合材料科学、地球化学和地质微生物学，实时研究玻璃在动态复杂的自然环境中是如何被腐蚀的。我将使用Ballidon长时间实验来提高对影响腐蚀的关键因素(温度、地下水地球化学、饱和度和微生物)的理解，在那里玻璃样品已经被埋藏了近50年。为了预测未来几千年后核废料玻璃的耐久性，我将研究与英国和美国处置概念相关的模拟核废料玻璃。这项新调查的结果将是在玻璃耐久性测试的基础上进行批判性评估和改进，建立改进的玻璃腐蚀模型，并建立进一步的长期实验，为英国和国外的地质处置提供安全案例。

Understanding the long-term durability of nuclear waste glass in the subsurface is important in the UK and internationally as many countries intend to dispose of vitrified radioactive waste in underground geological disposal facilities. In order to ensure safe disposal, we need to be confident that radioactive elements will remain isolated and immobilised for sufficient time to allow radioactivity to decay to safe levels. There will be multiple barriers in place (e.g. a metal container and engineered backfill) to delay groundwater from reaching the nuclear waste glass but eventually contact with water is expected. Although there are a number of laboratory tests currently used to determine the rate of glass dissolution in water all accelerate corrosion by increasing the temperature, surface area, or both and give very different predictions depending on the test conditions. Laboratory tests are also performed under simplified, stable, sterile conditions and using deionised water taking no account of how changing geochemical conditions will affect glass corrosion rates. This fellowship will combine materials science, geochemistry and geomicrobiology to study how glass corrodes in real-time in dynamic complex natural environments. I will improve understanding of key factors affecting corrosion (temperature, groundwater geochemistry, saturation, and microbiology) using the Ballidon long duration experiment, where glass samples have been buried for nearly 50 years. To predict the durability of nuclear waste glass thousands of years into the future I will study simulant nuclear waste glass's in conditions relevant to UK and US disposal concepts. The result of this novel investigation will be to critically evaluate, and improve, upon durability tests for glass, to build an improved model of glass corrosion and to establish further long duration experiments to inform the safety case for geological disposal in the UK and abroad.