Determination of the Distribution of Uranium in Glass Solidified Samples by Secondary Ionization Mass Spectrometry
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摘要: 玻璃固化是一种常用的高放废液固化方法,其优点在于具有较高的抗化学介质侵蚀的能力和很好的辐照稳定性、热稳定性和机械稳定性,其不足之处在于抗水浸出等性能有所下降而使其安全性需要进一步通过抗浸出实验来进行衡量和确认。使用二次离子质谱(SIMS)分析玻璃固化体中的放射性成分(如铀元素)的分布及浸出行为等各项指标,是一种评估玻璃固化体抗浸出性能的分析手段。本文应用SIMS测试模拟玻璃固化体,以碳作为镀膜材料通过真空蒸发镀碳的方法优化样品制备条件,有效地解决了样品导电性差的问题,235U/238U同位素测定结果约为7.9‰±0.395‰,基本符合制作模拟样品时所使用的天然铀的同位素特征(235U/238U参考值约7.3‰)。研究表明,建立的方法实现了铀元素同位素丰度的测量,能直接显示铀的分布情况,该方法可为研究玻璃固化体中放射性元素的浸出行为提供一定的技术支持。Abstract: Glass solidification is a common method for curing highly radioactive waste liquid. This method has the advantages of high resistance to chemical corrosion, and good radiation, thermal, and mechanical stability. However, the disadvantage is the decline of resistance to water leaching so that the reliability of the result needs to be confirmed by an anti-leaching test. Using Secondary Ionization Mass Spectrometry (SIMS) to analyze the composition distribution and leaching behavior of radioactive components (such as uranium) in the solid glass is a method for evaluating the ability of resistance to leaching of solidified glass. The simulated glass solidified sample was tested by SIMS and the results are reported and discussed in this paper. Carbon was used as the coating material during vacuum evaporation coating on the surface of the sample in order to overcome the poor conductivity of the sample. The isotopic composition of natural uranium is about 7.3‰. And the ratio of 235U/238U in the prepared solid glass is 7.9‰±0.395‰. The research indicates that the method can determine the measurement of the isotopic abundance of uranium and directly show its distribution. This method can provide technical support for the study of the leaching behavior of radioactive elements in solidified glass samples.
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Key words:
- glass solidified samples /
- leaching behavior /
- SIMS /
- uranium /
- isotopic abundance
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表 1 不同镀膜条件影响
Table 1. Different coating conditions
样品编号 镀膜仪器 镀膜时长 电阻值 A JEE-420型镀碳仪 4 min 超量程 B JEE-420型镀碳仪 8 min 10 MΩ C SC7620型溅射镀膜仪 100次 5 MΩ D SC7620型溅射镀膜仪 240次 5 MΩ -
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