Intermediate range order effects in radioactive waste glasses: implications for aqueous durability and mechanical properties

放射性废物以各种放射性元素的形式存在，在被处置在地质储存库之前，必须将其固定在玻璃或陶瓷或复合材料的基质中。这种通常被称为废物形式的基质必须能够容纳废物中存在的各种物种，并在放射性物种的寿命(通常为10,000年或更长时间)内抵抗淋溶和机械破裂。玻璃具有无定形结构，能够容纳各种放射性废物。此外，玻璃制造技术已经很成熟，可以大规模生产这些废物形式，这在英国和印度以及其他几个国家已经进行了几年。拟议的项目旨在根据辐射效应引起的原子级结构变化，了解放射性废玻璃中的相稳定性、热效应和辐射效应。然后，这些修改将与玻璃溶解和机械性能(如破裂/断裂)相关。选择的玻璃对英国和印度的放射性废物管理项目至关重要，从而补充了利用核技术实现清洁、安全和经济能源的方法和科学专业知识，同时提供了最可靠的废物处理安全案例。我们的具体目标将是：(1)了解玻璃的相稳定性作为不同二价阳离子和添加废物物种的函数；(2)在已经无定形/无序的材料系统中定义“辐射损伤”，并预测辐射诱导的修饰将如何影响长时间尺度上的溶解性能；以及(3)了解玻璃结构和性能在温度梯度下和经过退火热处理后的演变。为了让放射性废物不再被视为一个“问题”，而不是一种可以被公众舆论信任的做法，用来固定放射性废物的方法和材料必须从根本上得到理解和科学验证。这个项目旨在提高这种信心。我们的详细用户参与战略将确保公众和可能参与选择地质处置设施的社区成员、核工业和供应链、政府和公务员以及广泛的学者在整个项目和项目之外都将参与进来，以从我们拟议的研究中产生最大影响。

Radioactive waste occurs as a wide variety of radioactive elements that must be immobilised in a matrix of glass or ceramic or a composite, before disposal in a geological repository. This matrix, commonly known as the waste form, must be able to accommodate the wide range of species present in the waste and be resistant to leaching and mechanical fracture for the lifetime of radioactive species, typically 10,000 years or more. Glass, having an amorphous structure, is able to accommodate a wide range of radioactive waste species. In addition, glass fabrication technology is well established to produce these waste forms at large scale and this has been carried out for some years in both the UK and India, among several other countries. The proposed project aims to understand the phase stability, thermal and radiation effects in radioactive waste glasses, in light of atomic scale structural changes due to radiation effects. These modifications will then be correlated with glass dissolution and mechanical properties such as cracking/fracture. The glasses selected are critical to the radioactive waste management programs in the UK and India, thus complementing methods and scientific expertise to realise clean, safe and economical energy from nuclear technology whilst presenting the most robust safety case for waste disposal. Our specific aims will be to: (1) understand the phase stability of glasses as a function of different divalent cations and addition of waste species; (2) define 'radiation damage' in an already amorphous/disordered material system and predict how radiation-induced modifications will affect dissolution properties over long timescales; and (3) understand the evolution of glass structure and properties under a temperature gradient and after undergoing annealing treatments. In order that radioactive waste should no longer be deemed as an 'issue' rather than a practice that can be trusted by public opinion, the methods and materials employed to immobilise radioactive waste must be fundamentally understood and scientifically verified. This project aims at improving this confidence. Our detailed User Engagement Strategy will ensure that groups from the public and members of communities that may be involved in selection of a geological disposal facility, as well as the nuclear industry and supply chain, government and civil servants, and a wide range of academics, will be engaged throughout and beyond this project to deliver maximum impact from our proposed research.