Thermodynamic Model of Waste Tank Corrosion with Implications to Pitting during in-Tank Processing, Washing and Storage

摘要

The electrochemical thermodynamics of iron dissolution can be applied to past studies of pitting and general corrosion of carbon steel waste tanks for the storage of radioactive waste. Such studies seek to reproduce in the laboratory the electrochemical conditions existing in waste tanks. The tests employed are either coupon tests in solutions intended to be typical of the environment, or potentiodynamic or potentiostatic tests which impress a voltage on the sample, and measure the resulting electric currents. All types of test samples are microscopically examined for crevice or pitting corrosion. This review discusses the electrochemical processes that occur during such testing. By stating the assumptions which are inherent in such testing, this review seeks to familiarize process engineers and chemists with the conditions favorable for pitting corrosion, and some of the means of controlling it. Also included is a review of the conditions which exist during the washing and storage of cesium tetraphenylborate, and high aluminum waste. Implications of the model to the chemical control of pitting during these processes are summarized, along with potential alternative methods of controlling the pitting. 29 refs., 8 figs., 8 tabs. (ERA citation 14:000217)