High-strength materials were used in the design and fabrication of a Void Fraction Instrument that would be used in the caustic Hanford waste tank environments. Little corrosion data was available to predict the corrosion susceptibility of the high-strength materials in the tank environment. Limited scope testing has been performed to assess the susceptibility of these materials to uniform and localized corrosion in a caustic waste simulant based on the chemical composition of tank SY-101. The materials were found to be resistant to both uniform and localized corrosion for the limited duration of the testing. Keywords: Radioactive waste tanks, high-strength materials, Void Fraction Instrument