[3I07-09] Denitration, high-level liquid waste, pyro-processing

[3I08] Study on ruthenium volatilization during evaporation and dryness of nitrate solution

Volatilization of tetroxide ruthenium during long-time dryness and decomposition of nitrates

*Tetsuya Kato¹, Tsuyoshi Usami¹, Takeshi Tsukada¹ (1. CRIEPI)

Keywords:High level liquid waste, Ruthenium, Volatilization, Loss of coolant function, Boiling and drying accident

In a cooling malfunction accident of a high-level liquid waste (HLLW) tank, behavior of ruthenium (Ru) attracts much attention, since Ru could be oxidized to a volatile chemical form in the boiling and drying out HLLW, and part of radioactive Ru is potentially released to the environment. The release fraction of Ru to the initial load is considered to depend on a heating duration from the previous research. Thus, in this study, nitrates containing Ru was heated, and the gases of RuO₄ and so on evolved for a duration more than 1 hours were measured by means of the mass spectrometer.