Multifunctional Materials Laboratory (M&M) Lab, Inamori School of Engineering, The New York State College of Ceramics, Alfred University, Alfred, NY, 14802, USA.
Savannah River National Laboratory, Aiken, SC, 29808, USA.
Sci Rep. 2021 Feb 25;11(1):4512. doi: 10.1038/s41598-021-84014-1.
The long-term performance, or resistance to elemental release, is the defining characteristic of a nuclear waste form. In the case of multiphase ceramic waste forms, correlating the long-term performance of multiphase ceramic waste forms in the environment to accelerated chemical durability testing in the laboratory is non-trivial owing to their complex microstructures. The fabrication method, which in turn affects the microstructure, is further compounding when comparing multiphase ceramic waste forms. In this work, we propose a "designer waste form" prepared via spark plasma sintering to limit interaction between phases and grain growth during consolidation, leading to monolithic high-density waste forms, which can be used as reference materials for comparing the chemical durability of multiphase waste forms. Designer waste forms containing varying amounts of hollandite in the presence of zirconolite and pyrochlore in a fixed ratio were synthesized. The product consistency test (PCT) and vapor hydration test (VHT) were used to assess the leaching behavior. Samples were unaffected by the VHT after 1500 h. As measured by the PCT, the fractional Cs release decreased as the amount of hollandite increased. Elemental release from the zirconolite and pyrochlore phases did not appear to significantly contribute to the elemental release from the hollandite phase in the designer waste forms.
长期性能（或抵抗元素释放的能力）是核废料形式的决定性特征。对于多相陶瓷废料形式，由于其复杂的微观结构，将其在环境中的长期性能与实验室中加速的化学耐久性测试相关联并非易事。制造方法（反过来又会影响微观结构）在比较多相陶瓷废料形式时更加复杂。在这项工作中，我们提出了一种通过火花等离子烧结制备的“设计废料形式”，以限制在固结过程中各相之间的相互作用和晶粒生长，从而形成整体高密度废料形式，可作为比较多相废料形式化学耐久性的参考材料。合成了在固定比例的烧绿石和钙钛矿存在下含有不同量的方镁石的设计废料形式。采用产品一致性测试（PCT）和蒸汽水合测试（VHT）评估浸出行为。在 1500 小时后，VHT 对样品没有影响。根据 PCT 测量，随着方镁石含量的增加，Cs 的释放分数降低。在设计废料形式中，来自烧绿石和钙钛矿相的元素释放似乎并没有显著导致方镁石相的元素释放。
