The composition and structure of crud taken from the fuel elements of various PWR’s were determined by SEM, EDAX, X-ray analysis, infrared spectroscopy, and thermomagnetic analysis. The samples were taken from reactors varying in materials of construction from all stainless steel to mainly Inconel 600 and Zircaloy fuel cladding. It is shown that crud is essentially a nickel ferrite NixFe3-xO4 with 0.45 < x < 0.75. Calibration of the lattice parameter versus x allows convenient determination of the main constituents of crud samples. Chromium also enters the inverse spinel lattice substitutionally to give a composition CryNixFe3-x-yO4. Aluminum, when present, generally forms amorphous compounds with silicon.

In order to obtain information on the condition of deposition and dissolution of crud in the primary in the presence of temperature gradients, the solubility of iron and nickel from a synthetic nickel ferrite was determined in solutions of lithium hydroxide and boric acid of varying pH and hydrogen content. The solubility in pure boric acid was also measured between 300°C and room temperature under conditions relevant to shutdown procedures. The implications of these solubility data are briefly discussed.

Subject
Acids, Materials, Composition, Reactors, Iron, Solubility, Coolants, Acidity, Nickel, Elements, Cations, Ferrite, Samples
© 1978 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).
1978
Association for Materials Protection and Performance (AMPP)
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