In fast reactor investigation with lead-bismuth eutectic(LBE) coolant, understanding the source term within the reactor and its environmental migration is crucial for managing radiation hazards from ²¹⁰Po aerosols. The numerical simulations using empirical parameters have proffered insights into the theoretical migration and settling rates of ²¹⁰Po aerosols. However, the scarcity of platform tests has impeded the acquisition of particle size distributions and settling velocity, thus weakening the mutual confirmation between experimental and theoretical validation. In this study, an LBE aerosol testing platform (LATP) was designed and established to obtain the particle concentration data to predict ²¹⁰Po migration, where Te was employed as an experimental surrogate. The particle concentration and size distribution function of PbTe-doped LBE aerosol were measured by an aerosol spectrometer and a universal scanning mobility particle sizer, revealing the particle size distribution spanning from 0 to 800 nm. Under normal operating conditions (873 K), the pinnacle particle size of the aerosol concentration is 47 nm, which shifted to 41 nm under accident conditions (1223 K). Notably, the highest mass concentration of particles under both circumstances falls within the 200-300 nm range. The settling velocity of PbTe-doped LBE aerosol increase with the particle size, and ranging from 5.0×10^-7 to 7.1×10^-5m/s. First-principles calculations and X-ray photoelectron spectroscopy results indicate that PbTe-doped LBE aerosols should preferentially generate TeO₂ during the interaction with oxygen. This work provide a reasonable prediction method for the migration characteristics of polonium under severe accident.

中文翻译：

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PbTe 掺杂 LBE 气溶胶的沉积行为和 Te 价态预测：平台检验和第一性原理计算


在使用铅铋共晶 （LBE） 冷却剂进行快堆研究时，了解反应堆内的源项及其环境迁移对于管理 ²¹⁰Po 气溶胶的辐射危害至关重要。使用经验参数的数值模拟为了解 ²¹⁰Po 气溶胶的理论迁移和沉降速率提供了见解。然而，平台测试的稀缺性阻碍了粒度分布和沉降速度的获取，从而削弱了实验验证和理论验证之间的相互确认。在本研究中，设计并建立了 LBE 气溶胶测试平台 （LATP） 来获得预测 ²¹⁰Po 迁移的粒子浓度数据，其中 Te 被用作实验替代物。通过气溶胶光谱仪和通用扫描迁移率颗粒测量仪测量了 PbDive 掺杂 LBE 气溶胶的颗粒浓度和粒径分布函数，揭示了从 0 到 800nm 的粒径分布。在正常操作条件 （873K） 下，气溶胶浓度的峰值粒径为 47nm，在事故条件下 （41K） 移至 1223nm。值得注意的是，在这两种情况下，颗粒的最高质量浓度都在 200-300nm 范围内。PbTe掺杂LBE气溶胶的沉降速度随粒径的增加而增大，沉降速度范围为5.0×^10-7至7.1×^10-5m/s。第一性原理计算和 X 射线光电子能谱结果表明，PbTe 掺杂的 LBE 气溶胶在与氧气相互作用过程中应优先产生 TeO₂。本工作为严重事故下钋的迁移特性提供了一种合理的预测方法。