Despite the selection of materials that have good corrosion resistance in light water reactor (LWR) environments – austenitic stainless steels, Alloy 600 and their weld metals – there has been a significant incidence of stress corrosion cracking (SCC) in many components in both boiling and pressurized water reactors (BWRs and PWRs). Extending plant lifetime to 60, 80 or 100 years will require superior materials, which can only be identified by knowing their vulnerabilities and probably by improving their fabrication and microstructure. A few categories of superior materials have surfaced such as ~30% Cr, ~9% Fe Alloy 690; ~21% Cr, ~42% Fe Alloy 800; higher Cr and Ni stainless steels; and ~5 – 12% Cr ferritic steels. This paper discusses some of the benefits and vulnerabilities of each category and its variants, presents data showing that intermediate Cr/Fe alloys such as Alloy 800 and Alloy 825 are not sufficiently resistant to SCC, and examines the SCC resistance of this class of material when the Cr level is elevated to ~25% Cr.

Subject
Crack growth, Water, Materials, Stainless alloys, Boiling water reactors, Corrosion rate, Nickel based alloys, Sulfates, Oxygen, Alloys, Corrosion potential, Weld metal, Stress corrosion cracking
Keywords:
Stress corrosion cracking, light water reactors, structural materials, welds, water chemistry, Cr effects, Alloy 800, Alloy 825, Alloy 690, extended plant life
© 2013 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).
2013
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.