A program was established under an EPRI contract to analyze deposits on steam generator manway inserts, tubing, and crossover piping obtained from 16 plants. The types of analyses included spectroscopy, radiochemical, chemical, scanning electron microscope (SEM), and energy-dispersive x-ray (EDAX) techniques to characterize the surfaces and composition of the crud removed from the surfaces.

The Co-60 in deposits removed from steam generator tubes was observed to increase with time of plant operation. This trend is similar to that calculated by the CORA mathematical activity transport model. The unit surface activity deposited on stainless steel piping and manway inserts is about 15 times that found on the Inconel tubing and about 3 times that on the Zircaloy core.

The tubing oxide film is enriched in chromium relative to the Inconel tube material and is most likely a mixture of iron-nickel-chromite and metallic nickel. This film is quite distinctive from the core deposits. The cobalt concentrations in the tube films are about 10 times higher than in the tube material. Similarly, the chemical composition of the crud removed from the inserts is unlike that of the stainless steel base material.

Subject
Pipe surfaces, Steel surfaces, Materials, Piping, Tubes, Steam generators, Descaling, Tubing, U bends, Cobalt, Deposit corrosion, Nickel, Samples
© 1984 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).
1984
Association for Materials Protection and Performance (AMPP)
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