Tritium release behavior of Li4SiO4 and Li4SiO4 + 5 mol% TiO2 ceramic pebbles with small grain size

The tritium release behavior of the Li₄SiO₄ pebbles and Li₄SiO₄ + 5 mol% TiO₂ pebbles with small grain sizes was investigated. The tritium release results of Li₄SiO₄ pebbles with different grain sizes (0.3 μm and 1.5 μm) indicated that the grain size had little effect on the tritium release regardless of the difference in gas composition of purge gas. Moreover, the tritium release of small grained pebbles was dominated by the desorption process, since the addition of H₂ to purge gas substantially affected the release behavior. The modified Li₄SiO₄ pebbles with addition of TiO₂ exhibited enhanced water formation capacity due to the increased concentration of active point as the oxygen supplier. Obvious tritiated water release peaks around 690 °C could be observed from the Li₄SiO₄ + 5 mol% TiO₂ pebbles under 0.1%H₂+He purge gas. The modified Li₄SiO₄ pebbles also showed improved tritium release behavior, the tritium release peaks shifted to lower temperatures compared to Li₄SiO₄ pebbles.