ZnO和CaO对模拟高放废液硅酸盐玻璃固化体性能的影响研究

Effect of ZnO and CaO on Alkali Borosilicate Glass Waste-form Immobilizing Simulated Mixed HLW

针对有些高放废液含有较多Fe、Cr、Ni过渡金属元素,在玻璃固化工艺过程中易于形成晶体,导致熔融玻璃体的黏度增加、化学稳定性变差以及工艺过程中易出现出料口堵塞等问题,研究了废物包容量为15%和20%、添加ZnO(5.6%)和CaO(1.75%)的配方对形成的4种玻璃固化体的物理性能(密度、硬度、断裂韧性)、化学性能(产品一致性测试和蒸汽腐蚀测试)和结构(X射线衍射析晶分析、拉曼光谱分析)的影响。研究分析显示,提高废物包容量至20%以及添加ZnO和CaO均可促进硼硅酸盐玻璃固化体网络结构的稳定性和化学稳定性,并增强玻璃体的密度,提高硬度;但玻璃固化体的高温黏度升高,断裂韧性下降。

Since the transit metals,such as Fe,Cr and Ni,contained in some kinds of mixed HLW,can likely to form crystal,increase the melt viscosity,destroy the chemical durability and block the discharge port.The results obtained from investigating four glass waste-forms,including the alkali borosilicate glass matrix and alkali borosilicate glass matrix doped with 5.6%ZnO and 1.75%CaO in base matrixes,immobilizing the simulated mixed HLW with 15% and 20% waste loadings aiming to determinate the effect of ZnO on the alkali borosilicate glass chemical durability with waste loading increasing,were presented in this paper.Glass samples were characterized with XRD and Raman spectroscopy.The chemical durability was investigated using the standardprotocols PCT and VHT.The XRD analysis results show that spinel crystal appears and grows in glass samples at the waste loading in 20% without ZnO addition and waste loading in 15% and 20% added ZnO.The Raman spectroscopy analysis results indicate that ZnO and CaO can enhance the glass network connective,and the chemical durability test results display that the addition of ZnO and CaO can improve the short term chemical durability of the glass samples,except Zn20 obtained the lower value in VHT result,which is caused by the higher crystal ratio and lower fracture toughness.