Effect of Gadolinium Oxide on Structure and Chemical Stability of Borosilicate Glass with Simulated Nuclear Power Plants HLLW

Abstract

Because of its high radioactivity, high corrosivity, high toxicity and high heat release rate, safe and proper disposal of high-level liquid waste (HLLW) has always been the focus of radioactive waste management. After more than half a century of development, vitrification technology is a relatively mature technology widely recognized around the world that can achieve industrial scale treatment of HLLW. In recent years, with the rapid development of nuclear power in China, a certain amount of HLLW will be produced after reprocessing of the spent fuel produced each year. In order to properly and safely treat the HLLW generated from spent fuel reprocessing of nuclear power plants (NPPs), this paper conducted a study on the influence of adding gadolinium oxide (0%, 2%, 4%, 6%, 8% and 10%) on the structure and chemical stability of the solidified borosilicate glass on the basis of containing 20% simulated 33 GW·d/tU HLLW for the borosilicate glass base glass with the molar ratio of SiO2∶B2O3∶Na2O=1∶0.23∶0.54. XRD analysis shows that the glass samples are in stable amorphous glass state. Raman and NMR (nuclear magnetic resonance) analysis results show that, with the increase of Gd2O3 addition, the Si—O bound Q2 and Q3 structures in the glass structure tend to move to the low frequency region, and the proportion of B—O bound Q3 (B) structure gradually increases after a slightly decrease, while the proportion of Q4 (B) structure gradually decreases after a lightly increase. The chemical stability results show that the chemical stability of the glass solidified body samples is significantly improved with the addition of Gd2O3 and the leaching amount of Si, B, Na in the glass solidified sample is markedly reduced.

Keywords

• high-level liquid waste
• glass structure
• gd2o3