Pitting of stainless-steel canisters utilized in temporary storage nuclear fuel containers is a complex process that involves changes in relative humidity, temperature, as well as the type and the quantity of deliquescent salts. Prediction of the maximum pit expected to be developed in these canisters is of importance for regulatory agencies as the damage from subsequent stress corrosion cracking (SCC) can affect canisters’ lifespan. Chen and Kelly’s model in predicting the maximum pit expected in these canisters has provided promising results; however, the input parameters utilized in the model have proven to be overconservative.1 The model utilizes the repassivation potentiation (Erp) as one of the parameters to determine the total cathodic current which can greatly affect the predicted maximum pit calculations. We have developed an approach that utilizes a combination of thermodynamic equilibrium calculations, potentiostatic, galvanostatic, and galvanodynamic electrochemical tests, and in-situ electrochemical microscopy experiments to estimate the true Erp of stainless steel 316L in 0.6M NaCl.2,3 However, crevicing of the stainless-steel wire observed in these tests demand further validation of the obtained Erp values.In this study, the kinetics of the repassivation of stainless steel 316L will be investigated in chloride solutions and various brine compositions representing different relative humidities. A theoretical approach to predicting the chemistry inside of the pit will be presented. The results will be validated utilizing advanced electrochemical methods such as metallic bi-polar Luggin-Harber probe and in-situ microscopy.4 An attempt to expand the results in one-, two-, and three-dimensional stainless steel 316L pits will be shown.References Z. Y. Chen and R. G. Kelly, J. Electrochem. Soc., 157, C69 (2010). A. Shehi, S. Choudhary, and R. . Kelly, in AAMP 2023,, Denver, Colorado (2023).J. Srinivasan and R. G. Kelly, J. Electrochem. Soc., 163, C768–C777 (2016).S. Choudhary, K. Marusak, T. Eldred, and R. G. Kelly, J. Electrochem. Soc., 169, 111505 (2022).