Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, New York 12180, United States.
Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
Environ Sci Technol. 2021 Jun 1;55(11):7605-7614. doi: 10.1021/acs.est.0c07724. Epub 2021 May 11.
Advanced materials and processes are required to separate halides and fission products from complex salt waste streams associated with the chemical reprocessing of used nuclear fuels and molten salt reactor technologies for immobilization into chemically durable waste forms. In this work, we explore an innovative concept using metal halide perovskites as advanced host phases to incorporate Cs and Cl with very high waste loadings. Wet chemistry-synthesized CsSnCl powders from CsCl salt solutions are successfully encapsulated into a silica matrix to form a composite using low-temperature spark plasma sintering with tunable Cs and Cl loadings up to 31 and 26 wt %, respectively. Chemical durability testing of the composite waste forms by semi-dynamic leaching experiments demonstrates that an incongruent leaching mechanism dominates the release of Cs and Cl. The metal halide perovskite-silica composite waste forms display exceptional chemical durability with the long-term release rates of Cs and Cl comparable to or outperforming the state-of-the-art waste form materials but with significantly higher waste loadings. The scalable synthesis of the metal halide perovskite from wet chemistry processes opens up new opportunities in designing advanced waste forms for salt wastes with very high waste loadings and exceptional chemical durability for the sustainable development of advanced fuel cycles and next-generation reactor technologies.
需要先进的材料和工艺来从与乏核燃料后化学处理和用于固化的熔盐反应堆技术相关的复杂盐废物流中分离卤化物和裂变产物，并将其转化为化学稳定的废物形式。在这项工作中，我们探索了一种创新的概念，使用金属卤化物钙钛矿作为先进的主相，以非常高的废物负载量来容纳 Cs 和 Cl。从 CsCl 盐溶液中通过湿化学合成的 CsSnCl 粉末成功地封装到二氧化硅基质中，通过低温火花等离子体烧结形成复合材料，可调 Cs 和 Cl 的负载量分别高达 31 和 26wt%。通过半动态浸出实验对复合废物形式的化学稳定性进行测试，表明非均相浸出机制主导了 Cs 和 Cl 的释放。金属卤化物钙钛矿-二氧化硅复合废物形式具有优异的化学稳定性，Cs 和 Cl 的长期释放率与最先进的废物形式材料相当甚至更好，但废物负载量明显更高。从湿化学工艺合成金属卤化物钙钛矿为高废物负载量的盐废物设计先进的废物形式以及为先进燃料循环和下一代反应堆技术的可持续发展提供具有优异化学稳定性的废物形式开辟了新的机会。
