Nuclear Waste Glass Durability as a Function of Groundwater Composition

地下水溶液的复杂性质使得难以预测不同化学性质的地下水如何影响玻璃溶解，例如，如果来自一个潜在GDF站点的花岗岩地下水含有Mg，但另一个不含Mg，则如何根据一般花岗岩地下水预测长期玻璃行为？为了实现详细的机械理解，使用简化的解决方案的逐步方法是必要的。检查单个离子种类，并建立能够描述每个单个离子以及离子种类的不同组合如何一起影响玻璃的耐久性的模型是有利的，因为可以开发对长期行为的更详细的分析，并以溶解过程的彻底地球化学理解为基础。为建立英国核废料玻璃溶解的地球化学模型提供信息（包括成分MW、Ca/Zn、POCO、BUTEX和ISG）作为地下水离子种类的函数，该项目将利用多技术方法，包括：i）玻璃粉动态流过实验（SPFT测试）; ii）现场表面分析技术iii）长期静态粉末溶解试验; iv）在1至3年的时间尺度上的长期静态整料溶解测试，定期取样和表面表征（例如VSI、EDX、TOF-SIMS、X射线同步加速器技术、TEM与ORNL合作）;五）对所获得的所有溶液数据进行地球化学和热力学建模（例如PHREEQC、GEMS、GRAAL模型的应用），以确定蚀变层的形成机制，确定不同溶液中溶解的地球化学控制因素，并预测英国高放废物玻璃在广泛地下水中的行为。预计，这一建模工作将部分在国家核实验室进行。

The complex nature of groundwater solutions makes it difficult to predict how groundwaters of different chemistry influence glass dissolution, for example, if a granite groundwater from one potential GDF site contains Mg, but another does not, how is it possible to make predictions of long-term glass behaviour based on a generic granite groundwater? To achieve a detailed mechanistic understanding, a step-wise approach using simplified solutions is necessary. Examining individual ionic species, and building a model that is capable of describing how each individual ion, and how different combinations of ionic species together, influence the durability of glass is advantageous since a more detailed analysis of long-term behaviour can be developed, underpinned by a thorough geochemical understanding of the dissolution process. To provide information to build a geochemical model for the dissolution of the UK's nuclear waste glass (including the compositions MW, Ca/Zn, POCO, BUTEX and ISG) as a function of groundwater ion species, this project will utilise a multi-technique approach involving:i) Dynamic flow-through experiments with glass powder (SPFT tests);ii) In-situ surface analysis techniques (e.g. vertical scanning);iii) Long-term static powder dissolution tests;iv) Long-term static monolith dissolution tests on timescales of 1 to 3 years with periodic sampling and surface characterisation (e.g. VSI, EDX, TOF-SIMS, X-ray synchrotron techniques, TEM in collaboration with partners at ORNL);v) Geochemical and thermodynamic modelling of all solution data acquired (e.g. PHREEQC, GEMS, application to the GRAAL model) to determine the alteration layer formation mechanism, to identify the geochemical controls on dissolution in different solutions and to predict the behaviour of UK HLW glass in a wide range of groundwaters. It is anticipated that this modelling work will be performed, in part, at the National Nuclear Laboratory during a placement.