Nuclear wastes are stored in large, underground carbon steel storage tanks at the Hanford site. Most of the liquid wastes are highly alkaline, typically with pH values between 12 and 14. Under alkaline conditions, carbon steels tend to be passive and undergo relatively slow, uniform corrosion. However, carbon steels can be susceptible to localized corrosion (e.g., pitting) and stress corrosion cracking (SCC) in the presence of certain aggressive constituents under passive conditions. Furthermore, the passive films that form on carbon steel evolve over time. The pitting and SCC susceptibility of the passive film, as it evolves, is not well understood in these conditions. This paper presents work done to evaluate changes in SCC susceptibility over time as the passive film evolves. The slow strain rate (SSR) technique was used to evaluate carbon steel specimens immersed in alkaline waste simulants for up to 15 months. The results of the tests performed on aged specimens were compared with baseline tests performed on unaged specimens. 

Key words: conference papers, conference papers 2018, Carbon steel, passive film, SSR, stress corrosion cracking, Hanford, radioactive waste