Multi-phase ceramic and glass ceramic wasteforms are leading candidates for the immobilization of intermediate- and high-level radioactive wastes (ILW and HLW). Reliable prediction of their long-term performance requires accurate knowledge of phase assemblages, as phase composition strongly influences corrosion behaviour and wasteform durability. However, quantitative characterization of complex multiphase systems containing both crystalline and amorphous components remains challenging.
This presentation describes the application of X-ray diffraction (XRD) combined with Rietveld refinement for quantitative phase analysis of ceramic and glass-ceramic wasteforms. The internal standard method and the Partial Or No Known Crystal Structure (PONKCS) approach are employed to quantify crystalline and amorphous phases in heterogeneous materials. A key aspect of this work is the application of the PONKCS approach to wasteforms, providing a practical means of quantifying phases for which complete crystallographic information is unavailable and thereby improving the characterization of complex multiphase materials. Results from representative ceramic and glass-ceramic wasteforms demonstrate that these methods provide robust phase assemblage data, including amorphous content, and generate critical inputs for wasteform performance assessment and long-term corrosion modelling.