MODELING OF CRACK CHEMISTRY IN SENSITIZED STAINLESS-STEEL IN BOILING WATER-REACTOR ENVIRONMENTS

An advanced model has been used to predict the chemistry and potential in a stress corrosion crack in sensitized stainless steel in a boilin g water reactor (BWR) environment. The model assumes trapezoidal crack geometry, incorporates anodic reaction and cathodic reduction within the crack, and takes into account the limited solubility of cations in high temperature water. The results indicate that the crack tip poten tial is not independent of the external potential, and that the reacti ons on the walls of the crack must be included for reliable prediction . Accordingly, both the modelling assumptions of Ford and Andresen and of Macdonald and Urquidi-Macdonald, whilst having merit, are not full y satisfactory. Extended application of the model for improved predict ion of stress corrosion crack growth rate is constrained by limitation s in electrochemical data which are currently inadequate. Crown copyri ght (C) 1997 Published by Elsevier Science Ltd.