Synthesis and characterization of sodium-aluminophosphate based glass-ceramics containing NZP phase for HLW immobilization

Stable sodium-aluminophosphate (SAP) based glass-ceramics with sodium zirconium phosphate (NZP) crystal-line phase for high-level nuclear waste (HLW) immobilization were prepared by a melt-quenching process, and the effects of ZrO2 and B2O3 on their phase composition, structural features and properties were discussed in detail. The results show that the SAP based glass-ceramics obtained by the melt-quenching process show good aqueous durability and thermal stability. ZrO2 addition improves the formation of NZP phase but restrains the crystallization of AlPO4 phases. It is found that the correct ratios of ZrO2 and B2O3 allow only phase formation of NZP within the SAP glass, and the reasons were also analyzed. The conclusions demonstrate that the SAP based glass-ceramics with NZP phase as the crystalline phase are the potential matrices for specific HLW immobilization, and suggest that the melt-quenching process is an applicable way to prepare certain glass-ceramic waste forms.

Automated summary

This study discusses the effects of ZrO2 and B2O3 on the phase composition and properties of SAP-based glass-ceramics. The results show that ZrO2 addition improves the formation of NZP phase while restricting the crystallization of AlPO4 phases. The correct ratios of ZrO2 and B2O3 allow only the formation of NZP phase within the SAP glass.