Growing mechanism of dendritic oxide during sodium combustion

Nishimura, Masahiro ; Kamide, Hideki ; Sugiyama, Kenichiro*; Otake, Shiro*

The purpose of this study is to understand oxidation behavior of sodium precisely for FR safety against sodium combustion. It was recognized that dendritic oxide took an important role for the combustion reaction such as supplying the sodium to the reaction interface. In this study, we proposed a mechanistic model of supplying liquid sodium through the dendritic oxide based on the observation result of the growing behavior of dendritic oxide during combustion. In this model we made an attention to the kinds of chemical compounds. The formation of sodium peroxides can provide the sodium supplying route in the dendritic oxide. On the other hand the formation of sodium monoxide will block sodium supplying. The kinds of chemical compounds were decided by the Gibbs's free energy of thermodynamics in the reaction field such as temperature and oxygen concentration. This mechanistic model can explain the oxidation behavior consistently with the observation results.