[2B07-09] Severe Accident at Reprocessing Plant

[2B08] Study on ruthenium volatilization during evaporation and dryness of nitrate solution

Reduction of formation of volatile ruthenium tetroxide by addition of hydroxide

*Tetsuya Kato¹, Yuma Sekiguchi¹, Tsuyoshi Usami¹ (1. CRIEPI)

Keywords:High level liquid waste, Ruthenium, Volatilization, Neutralization, Loss of cooling function

In a cooling malfunction accident of a high-level liquid waste (HLLW) tank, part of radioactive ruthenium (Ru) is potentially released to the environment as volatile RuO₄. Since nitic acid and nitrites contribute to oxidize Ru to RuO₄, addition of neutralizing agent should reduce the formation of RuO₄. In this study, hydroxide as neutralizing agent was added into a simulated HLLW containing Ru, and the gases of RuO₄, HNO₃, and NOx evolved during the dryness and denitration up to 1073 K were measured by means of the mass spectrometer and the FT-IR to observe the formation behavior of RuO₄.