Storage of aluminum clad fuel and target tubes of the Mark 22 assembly takes place in the concrete-lined, light-water- filled, disassembly basins located within each reactor area at the Savannah River Site (SRS). A corrosion test program has been conducted in the K-Reactor disassembly basin to assess the storage performance of the assemblies and other aluminum clad components in the current basin environment.

Aluminum clad alloys cut from the ends of actual fuel and target tubes were originally placed in the disassembly water basin in December 1991. After time intervals varying from 45 – 182 days, the components were removed from the basin, photographed, and evaluated metallographically for corrosion performance. Results indicated that pitting of the 8001 aluminum fuel clad alloy exceeded the 30-mil (0.076 cm) cladding thickness within the 45-day exposure period. Pitting of the 1100 aluminum target clad alloy exceeded the 30-mil (0.076 cm) clad thickness in 107 – 182 days exposure.

The existing basin water chemistry is within limits established during early site operations. Impurities such as Cl-, NO3-, and SO4- are controlled to the parts per million level and basin water conductivity is currently 170 – 190 μmho/cm. The test program has demonstrated that the basin water is aggressive to the aluminum components at these levels. Other storage basins at SRS and around the U. S. have successfully stored aluminum components for greater than ten years without pitting corrosion. These basins have impurity levels controlled to the parts per billion level (1000X lower) and conductivity less than 1.0 μmho/cm.

Recommendations have been made to improve the basin chemistry using multiple deionizers down to levels at which long-term corrosion-free storage has been demonstrated. Clean-up activities are currently under way which should minimize future corrosion of the aluminum components in the storage basins at the Savannah River Site.

Subject
Pits, Water, Materials, Reactors, Nickel based alloys, Aluminum, Tubes, Rivers, Storage, Water chemistry, Pitting, Aluminum alloys, Alloys
Keywords:
Pitting corrosion, 1100 aluminum, 8001 aluminum, nuclear fuel, aluminum clad, reactor disassembly basin, Savannah River Site, SRS, Mark 22, K-Reactor
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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