硼硅酸盐玻璃固化体中ZnO对模拟高放废液Mo浸出率的影响及其模型预测

Effect of ZnO in borosilicate solidification glass on Mo leaching rate in simulated high-level radioactive waste and its model prediction

对于高钼核废料玻璃固化体而言,Mo浸出率是关键产品性能之一。在某高MoO_(3)(质量分数约为3%)模拟高放废液硼硅酸盐固化玻璃配方研究中,设计了ZnO含量的系列变化,进行了Mo浸出率的测试,依据实验数据建立了Mo浸出率的数理统计结构预测模型并进行了模型验证。结果显示,在研究配方范围内,Mo的浸出主要受约530 cm^(-1)处Si-O-Si摇摆振动及约1180 cm^(-1)处Q4基团中Si-O-Si弯曲振动的影响,且B_(2)O_(3)、Zr O_(2)及碱金属皆会影响这两个结构单元的相对浓度,进而影响Mo的浸出。在这种复杂玻璃系统中,ZnO含量的质量分数高于3.5%后Mo浸出率有一定程度增长。模型结果表明:建立的Mo浸出率结构模型具有较好的模拟精度及统计可靠性,模型迭代后的精度及可靠性皆获得了进一步提升,可用于设计成分范围内玻璃配方筛选中对Mo浸出率的迅速预判。

[Background]Mo leaching rate is one of the key product properties for high molybdenum radioactive waste vitrification.Furthermore,soluble molybdenum yellow phase is easy to precipitate,resulting in the enhancement of Mo leaching.It was reported that ZnO can promote the network stability and chemical durability in borosilicate glass to some extent.Whereas,if the composition of solidification glass is complex,then whether ZnO can still improve the chemical stability is worth studying.On the other hand,due to the long period of chemical stability test,it is hoped that the Mo leaching rate can be predicted by mathematical simulation to accelerate the research process.[Purpose]This study aims to investigate the effect of ZnO in borosilicate glass on Mo leaching rate in simulated high-level radioactive waste(HLW),and establish the prediction model of Mo leaching rate.[Methods]Firstly,a series multi-component borosilicate solidification glass samples with simulated high MoO_(3)(mass~3%)HLW and designed mass fractions of ZnO content of 1%,1.5%,3.5%,4%,4.5%,and 5%,respectively,were prepared for experimental test of Mo leaching rate.Then the glass structure gene modeling(GSgM)were employed to accurately simulate the glass properties using a small amount of data to establish the corresponding structural prediction model.Finally,Infrared spectrometer(IR),X-ray Diffraction(XRD),Differential Scanning Calorimetry(DSC)and thermal dilatometer(DIL)were used to test the transformation temperature,heating rate,coefficient of thermal expansion,etc.of the samples,and the model validation was also performed.[Results]Experimental results show that Mo leaching is mainly affected by Si-O-Si rocking vibration around~530 cm^(−1) andνSi-O-Si vibration in Q4 at~1180 cm^(−1),furthermore,B_(2)O_(3),ZrO_(2) and alkali variation influence the relative concentration of these two structural units,and then affect the Mo leaching.Mo leaching rate is enhanced with mass of ZnO over 3.5%in this complex glass system.[Conclusions]Model validation in this study proves that the structure model of Mo leaching rate has good simulation accuracy and statistical reliability,which are further improved after model iteration,hence can be used for the Mo-leaching prediction in the quick-screening of glass composition development.