Resolving Reaction Mechanisms, Kinetics and Mass Transport in Radionuclide-Loaded Geopolymer Cement Wasteforms

在英国，到目前为止，已经产生了超过15万米的放射性废物(足以填满60个奥运大小的游泳池)。这些放射性废物中的大多数都需要调理，要么将其包裹在水泥中，要么通过其他方法防止释放到生物圈。由于在腐蚀性环境中增强的耐化学性、对问题废物的化学耐受性增强、制备的较高流动性导致较高的废物负载量以及阳离子结合部位提供了增强的对放射性废物的捕获，因此在胶结放射性废物方面具有很大的吸引力。与其他包封剂替代品相比，土地聚合物表现出较低的裂变产物替代物的浸出率，这可能被用来证明更多的废物装载或处置边界废物以降低储存库等级。然而，在核封装设备所要求的这种条件下，关于哪些原材料参数对可靠应用至关重要的信息很少。该项目旨在通过研究基本粒子相互作用，更好地了解地质聚合物的反应、凝结和硬化，以便制定可靠的规范，并预测地质聚合物废物的性质和性能。该项目还旨在评估裂变产物的流动性，并建立化学耐久性和放射性废物保留。具体地说，它将：1.表征地质聚合物废物的相组合、微观和纳米结构以及孔隙网络结构。研究基本粒子相互作用，以便制定可靠的规范。确定放射性核素(如~(90)锶和~(137)Cs)与水泥的相互作用。评估放射性核素滞留情况。这将确定控制相演变的关键相互作用、微观、纳米和原子长度尺度上的结构演变、放射性核素-水泥相互作用、质量传输机制和淋溶阻力，以及与储存库相关的条件下的物理和化学稳定性。

In the UK, over 150,000m of radioactive waste (enough to fill 60 Olympic size swimming pools) has been produced to date. Most of this radioactive waste needs conditioning, by either encapsulating it in cement, or another method, prevent release to the biosphere. Geopolymer cements are attractive for cementation of radioactive waste due to enhanced chemical resistance in aggressive environments, enhanced chemical tolerance to problematic wastes, higher fluidity of preparation leading to higher waste loadings, and cation-binding sites that provide enhanced capture of radioactive waste.Geopolymers have demonstrated lower leach rates of fission product surrogates than other encapsulant alternatives and this may be used to justify greater waste loading or disposal of boundary wastes to lower repository ratings. However, there is little information on what parameters of raw materials are critical to reliable application, under such conditions required on nuclear encapsulation plants.This project aims to provides greater understanding of geopolymer reaction, setting and hardening, by investigating fundamental particle interactions, so that robust specifications can be developed, and geopolymer wasteform properties and performance can be predicted. The project also aims to assess mobility of fission products, and establish chemical durability and radioactive waste retention.Specifically, it will:1. Characterise geopolymer wasteform phase assemblage, micro- and nanostructure, and structure of the pore network.2. Investigate fundamental particle interactions so that robust specifications can be developed.3. Determine radionuclide (e.g. 90Sr and 137Cs)-cement interactions.4. Assess radionuclide retention. This will identify key interactions controlling phase evolution, structural evolution across micro, nano and atomic length scales, radionuclide-cement interactions mass transport mechanisms and leaching resistance, and physical and chemical stability in repository relevant conditions.