A simplified method is proposed for modeling the chemistry and potential distribution in a corrosion fatigue crack in sensitized stainless steel in boiling water reactor (BWR) coolant environments. Mass transport by diffusion, ion migration and convection due to movement of crack walls was considered. Anodic and cathodic processes, hydrolysis, oxide solubility, and water dissociation have been included in the model. The model takes into account transport processes in the external environment and recognizes that the specific rate (rate per unit area) of metal dissolution at the crack tip surface is much larger than the specific rate of dissolution on the (passive) crack sides. It has been shown that the pumping effect induced by fatigue influences the concentration and potential distributions within the crack. The crack tip potential and pH decrease with increasing stress intensity amplitude and frequency of mechanical loading. Keywords: corrosion fatigue, stress corrosion cracking, crack growth rate, boiling water reactors