Yachun Wang1 Weiguang Zhu1 Tiankai Yao1 Priyatham Tumurugoti1 Spencer Scott1 Jie Lian1

1, Rensselaer Polytechnic Inst, Troy, New York, United States

Within the DOE EFRC WastePD (Center for Design and Performance of Nuclear Waste Forms and Containers), the ceramic team targets the incorporation, confinement and transport behaviors of critical radionuclides in bulk crystalline ceramics and across solid-solid and solid-liquid interfaces that can be closely linked with the ceramic waste form degradation and stability under near field conditions. In this talk, the major activities of the ceramic waste form performance and degradation are highlighted with the focus on the development of crystalline host phases to address critical radionuclides of Cs, I and Cl, and their long-term performance. Promising ceramic waste forms are developed based upon apatite and defective perovskite structure types showing extensive cation and anion substitutions and crystal structure flexibility. Chemical dissolution experiments are performed on the designed ceramic waste forms to test their chemical durability and gain mechanistic understanding of the degradation mechanisms. In-situ synchrotron X-ray diffraction and environmental scanning electron microscopy observations are also performed to understand the phase transformation and dissolution behaviors for the ceramic waste forms with water interaction. Surface passivation of the ceramic waste form upon water interaction are also investigated and their impacts on ceramic waste form chemical durability are further discussed.