This paper presents the results of laboratory investigations performed to evaluate the susceptibilities of 304 and 316L stainless steels to localized corrosion in non-radioactive simulants of the process wastes in three types of tanks from the Effluent Treatment Facility (ETF) at the Hanford nuclear-waste storage facility; the Surge Tank (ST), the Secondary Waste Receiving Tanks (SWRTs), and the Concentrate Tanks (CTs). The results of Cyclic Potentiodynamic Polarization (CPP) testing indicate that 304H (UNS S30409), used as a surrogate for the legacy Type 304 stainless steel, and 316L (UNS S301603) stainless steels show no pitting susceptibility in
high-sulfate  waste simulants  for ETF tank environments, contrary to the inspection results of the tanks. CPP testing in control simulants confirmed that oxyanions present in the ETF wastes synergistically suppress pitting of 304H and 316L stainless steels. Crevice corrosion testing in low-sulfate waste simulants for ETF tank environments indicated varying degrees of susceptibility dependent on the oxyanion-to-chloride molar ratio of the simulant. Crevice growth test results suggest that the simulated ETF tank waste environments are not very conducive for growth of localized corrosion of 304H or 316L stainless steels.