Titanium-doped iron phosphate based glass ceramic waste forms containing 50 wt% simulated nuclear waste

Abstract

50 wt% of the simulated nuclear waste derived from the high level waste (HLW) in China is immobilized by using titanium-doped iron phosphate based glass ceramics. The effect of TiO2 content on the crystalline phases, structure and aqueous dissolution rate of the glass ceramic waste forms was investigated in detail. The results show that the crystalline phases of the obtained waste forms are monazite (Ce, La)PO4 accompanying with a small concentration of zirconium pyrophosphate ZrP2O7. The crystallization of ZrP2O7 phase is suppressed by adding TiO2 in the phosphate baseline glasses. Meanwhile, smaller grain size of the products is obtained. Moreover, the aqueous dissolution rates of the glass ceramic waste forms keep in the order of magnitude of 10−2 g m−2 d−1 after 14 leaching days, indicating their good chemical durability which are comparable to widely used borosilicate glasses and iron phosphate glasses/waste forms. The conclusions suggest that phosphate-based glass ceramics may potentially be an applicable matrix for the disposal of HLWs which are rich in actinide elements.