Waste package degradation expert elicitation panel: input on corrosion of CRM alloy C-22 Page: 3 of 33
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Draft Rev.8 - Joseph C. Farmer, LLNL, YMP WP Degradation, Expert Elicitation Panel, March 30, 1998
WASTE PACKAGE DEGRADATION EXPERT ELICITATION PANEL:
INPUT ON THE CORROSION OF CRM ALLOY C-22
Joseph C. Farmer, Ph.D.
University of California, Lawrence Livermore National Laboratory
7000 East Avenue or P.O. Box 808, Mail Stop L-352
Livermore, California 94550
Secretary (Nan Poggio) 510-422-9279
March 30, 1998 (Rev. 8); February 26, 1998 (Rev. 0)
The overall electrolyte concentration in the NFE environment is expected to be somewhere between iX
and saturated J-13 well water. This covers more than three orders-of-magnitude in chloride anion
concentration. The pH of this solution is expected to be somewhere between 5 and 10. Exposed patches
of the CRM could see this environment.
The pH in the crevice can be acidified due to the hydrolysis of dissolved polyvalent cations, such as Fe2+
As discussed by Oldfield and Sutton, metal ions produced by anodic dissolution are assumed to undergo
the following hydrolysis reactions [J. W. Oldfield, W. H. Sutton, "Crevice Corrosion of Stainless Steels:
I. A Mathematical Model," British Corrosion Journal, Vol. 13, No. 1, 1978, pp. 13-22]:
Fe2.+ H2O( K > Fe(OH)+ + H+
Fe'+ + H2O < K > Fe(OH)2+ + H+
Ni2+ +H20 < K Ni(OH)+ +H+
Cr3+ +H2O( K1 )>Cr(OH)2++ H+
Cr(OH)2++ H2O<- K )Cr(OH) 2+ H+
These reactions have also been considered in a crevice corrosion model published by the NRC [J. C.
Walton, S. K. Kalandros, "TWITCH - A Model for Transient Diffusion, Electromigration, and Chemical
Reaction in One Dimension," Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, CNWRA
92-019, 1992]. The range of pH expected under a worst-case scenario (no precipitation of FeCO3; no
leakage of dissolved metal or acid out of the crevice; no pH buffers; etc.) is illustrated by the data of Jones
et al., as shown in Table 1 [D. A. Jones, B. E. Wilde, "Galvanic Reactions During Localized Corrosion on
Stainless Steel," Corrosion Science, Vol. 18, 1978, pp. 631-643].
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Farmer, J. C.,LLNL. Waste package degradation expert elicitation panel: input on corrosion of CRM alloy C-22, report, March 30, 1998; California. (https://digital.library.unt.edu/ark:/67531/metadc675160/m1/3/: accessed April 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.