Zircaloy-4 spent nuclear fuel cladding is considered as an additional metallic barrier for the containment of radionuclides in the proposed repository at Yucca Mountain. In this investigation, localized (pitting and crevice) corrosion of Zircaloy-4 is studied as a function of temperature (25 to 95 °C), chloride concentration (0.001 to 4.0 M), and pH (2.1 to 10.7) in solutions containing the predominant anions in the groundwater to evaluate the behavior expected over a wide range of conditions. Cyclic potentiodynamic polarization curves are used to determine the values of parameters such as the repassivation potential that can be used in performance assessment models. Corrosion potentials are determined on specimens covered with thermally grown oxide films to evaluate the
possibility of localized corrosion under natural corroding conditions inside breached containers for spent nuclear fuel. Keywords: Zircaloy-4, localized corrosion, pre-oxidation