In recent years much attention has been focused on the use of hydrogen water chemistry (HWC) to control the electrochemical corrosion potential (ECP) of stainless steel in boiling water reactors (BWRs) to mitigate intergranular stress corrosion cracking (IGSCC) of sensitized 304 stainless steel (SS). It has been demonstrated that improving the surface catalytic activity of structural materials results in low ECPs below -230 mVshe for IGSCC protection under stoichiometric excess H2, even at high O2 levels. It was shown that a low ECP was achieved by lowering the oxidant concenteration at the catalytic surface to zero.

In this paper, the recombination efficiency for all oxidants present in 288°C water was evaluated using 304 SS containing 1% Pd under various water chemistry conditions containing stoichiometric excess hydrogen. It was shown that, with the proper geometry and flow rate, the 1% Pd alloy was sufficiently catalytic to recombine nearly all oxygen and hydrogen peroxide with hydrogen. The experimental data also showed that surface pretreatment in high temperature water or low temperature chemical solutions increased the catalytic efficiency.

Subject
Water, Materials, Intergranular stress corrosion cracking, Boiling water reactors, Hydrogen concentration, Materials performance, Metal surfaces, Pretreatment, Oxygen, Catalysts, Alloys, Hydrogen, High temperature
Keywords:
Corrosion potential, boiling water reactor, catalytic recombination, noble metals, high temperature water, stainless steel
© 1996 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).
1996
Association for Materials Protection and Performance (AMPP)
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