Extensive cracking of the Alloy 600 tubing in the once-through steam generators at the Three Mile Island Unit 1 Nuclear Power Plant was discovered in November 1981. The major findings of the subsequent failure analysis efforts undertaken by the Utility, the Vendor, and EPRI are summarized and are used to develop a scenario of the sequence of events that led to the tube cracking. It is concluded that the presence in the reactor coolant of aggressive sulfur- species formed during or immediately following hot functional testing in August/September 1981 caused stress assisted intergranular cracking of the tubes during the subsequent cold shutdown.

Subject
Sulfur, Water, Materials, Tubes, Sulfur species, Steam generators, Stress cracking, Failure analysis, Stress, Tubing, Alloys, Stress corrosion cracking, Oxidation
© 1983 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).
1983
Association for Materials Protection and Performance (AMPP)
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