Predictions of Enhancing Hydrogen Water Chemistry for Boiling Water Reactors by General Catalysis and General Inhibition

Abstract DAMAGE-PREDICTOR, the computer code with the capability of simultaneously estimating the concentrations of radiolysis species, the electrochemical corrosion potential (ECP), and the crack growth rate of a reference crack in sensitized Type 304 stainless steels, was used to evaluate the responses of Dresden-2 and Duane Arnold boiling water reactors (BWRs) to hydrogen water chemistry (HWC) with the application of general catalysis (increasing the exchange current density) and general inhibition (decreasing the exchange current density). HWC simulations for these two BWRs were carried out for feedwater hydrogen concentrations of 0.0, 0.5, and 1.0 ppm and for exchange current density multipliers of 10−4 (general inhibition) and 104 (general catalysis). Species concentrations (H2, O2, H2O2, etc.), electrochemical corrosion potential (ECP), and crack growth rate were predicted for the entire heat transport circuits (HTCs) of the two reactors. It is predicted that both techniques arc able to greatly improve the effectiveness of HWC for protecting the entire heat transport circuits of Dresden-2 and Duane Arnold. However, while operated under normal water chemistry, both reactors are predicted to become more susceptible to IGSCC because of the elevated ECP resulting from general catalysis. We emphasize, however, that this conclusion is tentative because the increase in the exchange current density values for general catalysis have not been experimentally determined.