| Abstract Scope |
Safe nuclear waste storage (NWS) is a crucial problem related to the increasing world demand for sustainable energy. Glasses and glass-ceramics are top candidates for NWS, with over 4,000 studies performed since 1959. Reported crystal phases include pyrochlore, zirconolite, powellite, oxyapatite, NaZr2(PO4)3, ZrP2O7, FePO4, sphene, and CaTiO3.They must have a formidable combination of properties: adequate glass-forming ability to suppress spontaneous crystallization, crystallize into phases and a residual glass of high chemical durability, dissolve high amounts of different radioactive elements in the crystal phases, and be stable against further crystallization during storage. In this talk, we will show positive features and difficulties regarding the application of nucleation and growth models to understand, describe and predict the crystallization kinetics and crystallization pathways of elaborate, non-stoichiometric oxide formulations such as those intended for NWS. We will discuss some relevant open issues: crystallization-induced pores, spontaneous cracking, thermal and microstructural gradients in monolithic pieces. |