Nuclear wastes are stored in large, underground carbon-steel storage tanks at the Hanford site. Most of the liquid wastes are highly alkaline in nature, typically with pH values between 12 and 14. Under alkaline conditions, carbon steels tend to be passive and undergo relatively slow, uniform corrosion. However, carbon steels can become susceptible to localized corrosion (e.g., pitting) and stress corrosion cracking (SCC) in the presence of certain aggressive constituents, such as chloride and nitrate, even in these passive conditions. Susceptibility to pitting and SCC can also be enhanced under conditions of elevated open-circuit potential (OCP). In this work, long-term immersion testing was conducted on carbon steel specimens in a set of alkaline waste simulants. Large OCP drifts ranging from about +150 mV to +350 mV were observed in several simulants. This paper presents the results of ongoing electrochemical investigations to understand the reasons behind the noble drift in the OCP of carbon steel in these waste simulants.

Subject
Test methods, Electrochemical impedance spectroscopy, Passive films, Density, Capacitance, Specimen preparation, Steel, Pitting, Carbon steel, Immersion, Wastes, Corrosion potential, Test specimen
Keywords:
Open-circuit potential, passive film, Mott-Schottky, tank steel, Hanford, radioactive waste
© 2017 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2017
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.