Disposal of nuclear waste by deep underground burial is being considered by the United States and many other countries. In many cases, the waste will be encased in an engineered waste package made of metal, concrete, or other materials. The ability of these disposal systems to limit the migration of radionuclides depends on a variety of factors, including the geochemical environment. If the waste package contains metallic parts, the corrosion reactions will dominate many aspects of the geochemistry in the immediate vicinity of a nuclear waste package. Some potential influences of metallic corrosion on the geochemical environment of the waste package are discussed. The corrosion reactions are a result of interaction or coupling of corrosion and geochemical processes. A generalized model is presented that describes the electrochemistry developed in corrosion cells and interaction with the surrounding geochemical environment. The model is first applied to laboratory data on crevice corrosion and then used to perform a parametric study. The results suggest that corrosion cells that lead to significant modifications to the geochemical environment are likely. The formation of corrosion cells around the waste package leads to large uncertainties concerning the geochemical environment in which radionuclide release rate and container corrosion will take place. Models and experiments of corrosion, waste form dissolution, and release rate need to take the expected uncertainty in geochemical environment into account.