In the United States, some spent nuclear fuel is stored in dry cask storage systems. Most dry storage systems use canisters fabricated from austenitic stainless steel. Canisters are exposed to the ambient atmosphere and literature data indicate that near regions of industrial, commercial, or agricultural activities, abundant airborne particulates may include sulfate, nitrate, and ammonium as well as a smaller amount of chloride. This study evaluated the stress corrosion cracking (SCC) susceptibility of as-received and sensitized UNS S30400 stainless steel exposed to ammonium nitrate mixed with sodium chloride salts. SCC tests were conducted at 45 °C-44% relative humidity using U-bend specimens coated with salt mixtures of ammonium nitrate and sodium chloride with mole ratios of 3 and 6. After a period of exposure of 1.5 months, examination of specimens showed that severe SCC occurred. The SCC severity is greater for specimens coated with ammonium nitrate and sodium chloride at mole ratio of 3. Previous work under this program showed that no SCC was observed on specimens exposed only to ammonium nitrate. The results indicate that chloride has a large effect on SCC initiation and nitrate did not inhibit SCC at the tested nitrate to chloride mixture mole ratios.

Subject
Salts, Deliquescence, Sodium chloride, Mixtures, Particulates, Nitrates, U bends, Efflorescence, Stainless steel, Chlorides, Relative humidity, Stress corrosion cracking, Chloride stress corrosion cracking
Keywords:
UNS S30400 stainless steel, stress corrosion cracking, U-bend, ammonium nitrate and sodium chloride mixture
© 2014 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).
2014
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.