Study on the Li Mass Loss From LTZO in the Blanket

Abstract

Li2TiO3 with additional Li is one of the promising materials to attain an overall tritium breeding ratio (TBR) over one to operate deuterium-tritium (DT) fusion power plants. However, unfortunately, some studies have clarified that the additional Li makes it unstable compared to ordinary Li2TiO3 pebbles and prone to evaporation as LiOH, causing corrosion damage to the surrounding structural material. Therefore, this work aimed to investigate the Li mass loss behavior of the ceramic pebbles recently developed, Li2+xTiO3+y + 20 wt% Li2ZrO3 (LTZO) through long-term heating experiments. It was concluded that it would eventually lose 1.5 wt% of LTZO as Li2O evaporation loss resulted from the interaction with water vapor. No structural changes due to the long-term heating for up to 30 days were observed through X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray (SEM-EDX). In addition, this work performed a simplified 1-D simulation based on the obtained experimental data. It showed that Li evaporation from the LTZO pebbles was so rapid that the benefits of additional Li for tritium production were limited. In contrast, the corrosion caused by LiOH generated through evaporation would need more attention. Compared to the Li burn-up rate, although this phenomenon would not negatively impact tritium production, Li evaporation would dominate more during the first four months of operation. Finally, several countermeasures were proposed to maximize the benefits of Li addition for tritium production.