In recent years reliability and availability of PWR Nuclear Steam Generators has been adversely affected by the occurence of intergranular stress corrosion cracking (SCC) and general intergranular attack (IGA) of the alloy 600 tubing.

SCC initiates both in essentially pure water and in caustic or other contaminated local environments. IGA is found only in local areas (e.g., crevices, sludge pile, etc.) where high concentration of impurities may accumulate.

"Pure water" initiated SCC has been found only in regions where tubing has been cold worked during fabrication (e.g., bends, etc.) or where a dynamic strain is imposed on the tube during plant operation. IGA may occur at any location where geometry and heat flux permit accumulation of a corrosive environment. In these locations IGA and SCC may both be seen; stress level probably being the key factor determining the morphology of the attack. Work is underway to define the causative and aggravating species which contribute to the corrosive environment.

Hypotheses have been developed to explain the corrosion observed.

Subject
Water, Materials, Intergranular stress corrosion cracking, Tubes, Steam generators, Water chemistry, Crevices, Tubing, U bends, Heat, Deposit corrosion, Alloys, Stress corrosion cracking
© 1982 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).
1982
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.