Abstract The mechanisms that affect the incorporation of Tc-99, a volatile radioactive component of concern, into glass melt during vitrification of low-activity waste (LAW) are being investigated to develop a method to increase the retention of Tc-99 in glass waste form. Previous studies with simulated LAW glass feeds (slurry mixture of liquid waste and chemical/mineral additives) demonstrated that the early stage feed-to-glass conversion reactions below 800 °C are critical for the retention of Re (used as a nonradioactive surrogate of Tc-99) in glass. To examine the effect of feed composition on the feed-to-glass conversion reactions, simplified systems containing major LAW components (NaNO3 and NaOH) and representative additive components (SiO2 and H3BO3) were designed and tested. The ratio of H3BO3 to NaNO3 was varied in a three-component system without NaOH and the ratio of NaOH to NaNO3 was varied in a four-component system at a fixed H3BO3 to NaNO3 ratio. As a first step of testing with simplified feeds, this study applied thermal analyses and phase characterization of the reacting feeds, which were performed without the addition of Re, to investigate the evolution of salt phases during the slurry drying process and upon heating of dried feeds.

中文翻译：

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简化的低活性废玻璃进料转化过程中的反应

摘要 正在研究在低活性废物 (LAW) 玻璃化过程中影响 Tc-99（一种令人关注的挥发性放射性成分）掺入玻璃熔体中的机制，以开发一种增加 Tc-99 在玻璃废物中保留的方法。形式。先前对模拟 LAW 玻璃进料（液体废物和化学/矿物添加剂的浆料混合物）的研究表明，低于 800 °C 的早期进料到玻璃的转化反应对于 Re（用作 Tc 的非放射性替代物）的保留至关重要-99) 在玻璃中。为了检查进料成分对进料到玻璃转化反应的影响，设计并测试了包含主要 LAW 成分（NaNO3 和 NaOH）和代表性添加剂成分（SiO2 和 H3BO3）的简化系统。H3BO3 与 NaNO3 的比率在没有 NaOH 的三组分系统中变化，而 NaOH 与 NaNO3 的比率在四组分系统中以固定的 H3BO3 与 NaNO3 比率变化。作为使用简化进料进行测试的第一步，本研究应用了反应进料的热分析和相表征，这些反应是在不添加 Re 的情况下进行的，以研究在浆料干燥过程中和干燥进料加热时盐相的演变.