Speaker
Ryoutarou Yamamoto
(Advanced of Energy Engineering science)
Description
Understanding of Li evaporation property is important because Li mass transfer decreases tritium breeding ratio and influences tritium behavior. In JAEA, the development of Li2TiO3with excess Li has been performed as an advanced tritium breeder. The present authors revealed in previous works that a layer existing on the pebble surface includes Li2CO3 and it contributes Li mass loss. Recently, Li2TiO3 pebbles without the surface layer were successfully fabricated by the emulsion method under optimized sintering condition in JAEA. In this work, Li mass loss property for newly fabricated pebbles was investigated.
Li2TiO3 pebbles with/without the surface layer are referred to as old (Li/Ti=2.10) / improved pebbles (Li/Ti=2.10). Sample pebbles were packed in a quartz tube and heated to 900 ooC in 50 Pa or 200Pa H2O/Ar. Li mass loss was estimated from the weight change of pebbles before and after the experiment taking account of the water vapor release. SEM observation was carried out before and after the experiment. In the additional experiment, CO2 release was measured by a gas chromatograph.
Li mass loss from improved pebbles was 1.0 wt% in 50 Pa H2O/Ar and 1.5 wt% in 200Pa H2O/Ar. Li mass loss from old pebbles was 1.5 wt% in 50 Pa H2O/Ar and 2.7 wt% in 200Pa H2O/Ar. It was found that Li mass loss from improved pebbles was smaller than that from old one. Although CO2release was observed from old pebbles over 600 ooC by the decomposition on Li2CO3, CO2 release was not detected from improved pebbles. Although the melting layer of Li2CO3 was observed on old pebbles after heating over 700ooC, Structure changes of improved pebbles were not observed by SEM observation. It can be said that Li mass loss from improved pebbles is progressed without the contribution of Li2CO3.
Co-authors
Kazunari Katayama
(Advanced of Energy Engineering science, kyushu universty, 6-1 kasugakouen kasuga-shi Fukuoka, Japan)
Ryoutarou Yamamoto
(Advanced of Energy Engineering science, kyushu universty, 6-1 kasugakouen kasuga-shi Fukuoka, Japan)
Satoshi Fukada
(Advanced of Energy Engineering science, kyushu universty, 6-1 kasugakouen kasuga-shi Fukuoka, Japan)
Toshiharu Takeishi
(Advanced of Energy Engineering science, kyushu universty, 6-1 kasugakouen kasuga-shi Fukuoka, Japan)
Tsuyoshi Hoshino
(Breeding Functional Materials Development Group, Japan Atomic Energy Agency, Rokkasho-mura, kamikita-gun, Aomori, Japan)
