Deposition behavior of PbTe doped LBE aerosol and Te valence prediction: platform test and first-principles calculation

Abstract

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.