高放射性核废料玻璃固化体结构与化学稳定性

Glass Structure and Chemical Durability of Phosphate Glass Wasteforms Containing High Level Radioactive Nuclear Waste

用溶解速率法(dissolutionrate)、试样坚固法(productconsistencytest)和蒸汽水化侵蚀法(vaporhydrationtest)对高放射性核废料(HLW)玻璃固化体的化学稳定性作了全面的测试,并对它们进行傅立叶变换红外光谱(FTIR)和X射线衍射(XRD)测试.FTIR分析表明,在较高的HLW包容量的玻璃固化体中,含有较少的容易被水化(PO3)1-的长链单元,因此它们具有优良的化学稳定性.XRD分析表明,玻璃固化体中分离的(P2O7)4-和(PO4)3-阴离子团被金属离子Fe3+,Cr3+等所连接,形成O—Me—O—P键,不仅提高了玻璃的抗析晶的能力,而且也大大地提高了化学稳定性.这些高包容量的玻璃固化体的原子比O/(Si+P)为3.7～4.1,从结构上也印证了HLW包容量达70%和75%(质量分数)的玻璃固化体会具有卓越的化学稳定性.

The chemical durability of iron phosphate (IP) glass containing different contents of high level radioactive nuclear waste (HLW) loading was measured by dissolution rate(DR) method,product consistency test(PCT) and vapor hydration test (VHT).The measurement shows that the IP glass wasteforms containing 65～75 mass % HLW waste loading have excellent chemical durability.The total elemental mass release determined by PCT for all these wasteforms was less them 2.0 g·m -2 ,and the corrosion rate determined by VHT was less than 0.2 and 3.5 g·m -2 ·d -1 ,for the glass containing 70 or 75 mass % HLW waste loading respectively.The glass structure of wasteform was analyzed by Fourier turn infrared(FTIR) and the structure unit of crystallized wasteform was revealed by X-radiation diffraction(XRD).The results indicate that the structure unit changed from (PO3) 1- groups to isolated (P2O7) 4- or (PO4) 3- groups with the increase of HLW waste loading in IP glass. When the atomic ratio of O/(Si+P) in the composition of these wasteforms containing high waste loading was between 3.7 and 4.1,the ions such as Al 3+ ,Fe 3+ ,Cr 3+ and Zr 4+ in the intermediate metal oxide can connect with the isolated (P2O7) 4- or (PO4) 3- groups by forming the O—Me—O—P bonds,which improved the resistant to be crystallized and enhanced the chemical durability.