The influence of ZrO2 on borosilicate glass solidification of TRPO wastes: microstructure and chemical stability

In this study, borosilicate glasses with different ZrO 2 contents were synthesized at 1200 °C and used to immobilize simulated TRPO waste. The effects of ZrO 2 content on the solid solution limit, microstructure, mechanical properties, and chemical stability of the solidified bodies were systematically analyzed. The results showed that with the increase of ZrO 2 content, the solid solution limit of TRPO waste increased from 20 to 30 wt%, and the degree of amorphization of the solidified bodies could be improved. The addition of ZrO 2 raised the number of bridging oxygen bonds in the solidified body and enhanced the degree of polymerization of the glass structure. For samples containing 4 wt% ZrO 2 , the highest Vickers hardness and density values were 6.57 GPa and 2.89 g cm −3 . Moreover, the 42-day normalized leaching rates of Ce, Nd, La, and Pr in the solidified bodies were about 10 −5  g m −2  d −1 . This work provides useful ideas for the optimization of the solidification matrix materials for high-level radioactive waste. Graphical abstract