Synthesis of pyrochlore-borosilicate glass-ceramics for immobilization of high-level nuclear waste

In this work, borosilicate based glass-ceramics with pyrochlore as crystalline phase for immobilization of high-level nuclear wastes (HLWs) were successfully synthesized by a one-step heat-treatment method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS) demonstrate that the obtained glass-ceramics show a regularly and uniformly distributed single pyrochlore (Ca,Na)(Nb,Ti)₂Nd_0.67O₆F crystalline phase. Moreover, the glass-ceramics prepared show LR_Na, LR_B, LR_Al, LR_Si, LR_Nd, LR_Ti and LR_Nb of about 6.8 × 10⁻³, 3.7 × 10⁻⁴, 1.5 × 10⁻², 2.2 × 10⁻³, 3.0 × 10⁻⁵, 5.1 × 10⁻⁵ and 5.5 × 10⁻⁶ g m⁻² d⁻¹ respectively after 28 leaching days, which are comparable to stable glass-ceramics for HLW immobilization. The results of this study are expected to provide an experimental reference for the engineering synthesis of glass-ceramics for the immobilization of certain HLWs.