Glass-Ceramic Wasteforms for High Level Wastes from Advanced Nuclear Fuel Reprocessing

用于固定化核燃料循环产生的高活性废物的微晶玻璃技术的成熟和开发的一个关键障碍是，对导致所需相组合和微观结构发展的分子级相分离和结晶机制的基本理解存在差距。这些特性决定了微晶玻璃废物在地质处置设施中的长期性能行为。为了最大限度地减少未来的储存、管理和处置成本，增加每个包装的废物负载量的需求导致了液-液相分离和复杂金属氧化物相(不受控制的)结晶的趋势。在这个项目中要解决的重大挑战是在可预见的情况下实现目标相组合和微观结构，需要详细了解转变过程作为冷却速度和熔体化学的函数。控制这种分相和析晶过程对于防止形成非耐久的晶体、玻璃或晶体-玻璃界面至关重要。这一认识对于英国、美国和其他地方的放射性废物管理项目至关重要，这些项目寻求利用微晶玻璃技术，或者相反地，优化传统的硼硅酸盐玻璃，以提高关键裂变产物和鳗系元素的溶解度。该研究项目是来自美国和英国的顶尖研究人员的联合合作项目，他们共同带来了互补和兼容的技能、能力和兴趣，以实现对用于放射性废物固定化的微晶玻璃中相关相分离和晶化机制的基本理解的范式转变。

A key barrier to maturation and exploitation of glass-ceramic technology, for immobilisation of high activity waste from nuclear fuel recycle, is the gap in fundamental understanding of the molecular-scale mechanisms of phase separation and crystallization, that lead to the development of the desired phase assemblage and microstructure. These characteristics determine the long-term performance behaviour of the glass-ceramic wasteform in a geological disposal facility. The demand for increased waste loading per package, to minimise onward storage, management and disposal costs, results in a tendency towards liquid-liquid phase separation and (uncontrolled) crystallization of complex metal oxide phases. The grand challenge, to be addressed in this project, is in predictably achieving the targeted phase assemblage and microstructure, requiring a detailed understanding of the transformation process as a function of both cooling rate and melt chemistry. Controlling this phase separation and crystallization process is critical to preventing the formation of a non-durable crystal, glass, or crystal-glass interface. This understanding is of paramount importance for radioactive waste management programs in the UK, USA, and elsewhere, which seek to exploit glass-ceramic technology or, conversely, optimize conventional borosilicate glasses to improve the solubility of key fission products and actinides. This research program is a joint collaborative enterprise between leading researchers from the US and UK who, collectively, bring mutually complementary and compatible skills, capabilities, and interests required to achieve a paradigm shift in the fundamental understanding of relevant phase separation and crystallization mechanisms in glass ceramics for radioactive waste immobilisation.