[2E19-21] Severe Accident, Fuel Debris, Corrosion

[2E21] Hydrogen Absorption Behavior of the R–SUS304ULC/Ta/Zr Dissimilar Metal Joint under NaOH–HNO3 Immersion

*Yasuhiro Ishijima¹, Fumiyoshi Ueno¹, Hitoshi Abe¹, Takahiro Igarashi¹ (1. JAEA)

Keywords:spent fuel reprocessing plant, tantalum, hydrogen embrittlement, dissimilar metal joint

In order to investigate the effect of tantalum (Ta) embrittlement caused by hydrogen absorption due to corrosion during decontamination of dissimilar metal joints, immersion tests and electrochemical measurements were conducted on dissimilar metal joint and pure Ta at various concentrations of sodium hydroxide and nitric acid in alternation with each other. As a result, it was found that hydrogen absorption into Ta in dissimilar materials was suppressed compared to that of pure Ta. From the electrochemical measurements, it is considered that this is due to the separation of the hydrogen source from Ta to the stainless steel and zirconium surfaces by the contact of Ta with stainless steel and zirconium, and the suppression of hydrogen adsorption by the passivation of Ta.