[en] Pourbaix diagrams for the copper in 5 molal chlorine at 5-100 deg C have been calculated. Predominance diagrams for dissolved copper containing species have also been calculated. Two different total concentrations of dissolved copper, 10^-4 and 10^-6 molal, have been used in the calculations. ChIoride is the predominating chlorine species in aqueous solutions. Therefore Pourbaix diagrams for chlorine can be used to discuss the effect of chloride solutions on the corrosion behavior of a metal. Presence of chloride increases the corrosion regions of copper at the expense of the immunity and passivity regions in the Pourbaix diagrams. Copper corrodes in 5 molal chloride by formation Of CuCl₃^2- in acid and alkaline solutions. At higher potentials in acid solutions CuCl₃^2- is oxidized to CuCl₂(aq), which at increasing potentials can form CuCI⁺, Cu²⁺ or CuClO₃⁺. Copper passivates by formation of Cu₂O(cr), CuO(cr), or CUO₂ 3 Cu(OH)₂(s). Cu₂O(cr) does not form at [Cu(aq)]_tot = 10^-6 molal in 5 m C1-, which results in a corrosion area between the immunity and passivity areas. Copper at the anticipated repository potentials and pH corrodes at 100 deg C at [Cu(aq)]_tot = 10^-4 molal and at 80-100 deg C at [Cu(aq)]_tot = 10^-6 molal. Copper at the anticipated repository potentials and pH can corrode at 80 deg C at [Cu(aq)]_tot = 10^-4 molal and at 50 deg C at [Cu(aq)]_tot = 10^-6 molal. The bentonite clay and copper canisters in the deep repository can be considered as a 'closed' system from macroscopic point of view. The clay barrier limits both inward diffusion of oxygen and aggressive anions as well as outward diffusion of corrosion products from the canisters. Both diffusion phenomena will drive the corrosion potential into the immunity area of the Pourbaix diagram for copper. The corrosion will thereby stop by an automatic mechanism. However, this is only valid if no macro cracks occur in the clay. The auto-stop is valid for the initial, main and cooling phases. During a glacial period the weight of the ice may cause macro cracks and thereby open the system, which will cause accelerated corrosion. The low temperature will decrease the kinetics of the anodic and cathodic reactions and thereby decrease the corrosion rate. However, the resulting reaction rate can be determined experimentally. Even considering radiolysis in the gap between clay and copper canisters, the conclusion of an auto-stop is still valid. This is due to the up-concentration of dissolved corrosion products, which cause the immunity area to increase. The corrosion potential will then fall into the immunity region and the corrosion will stop