General Corrosion and Localized Corrosion of Waste Package Outer Barrier REV 02, ICN 00 
ANL-EBS-MD-000003 
October 2004
1. PURPOSE 
The waste package design for the License Application is a double-wall waste package 
underneath a protective drip shield (BSC 2004 [DIRS 168489]; BSC 2004 [DIRS 169480]). The 
purpose and scope of this model report is to document models for general and localized 
corrosion of the waste package outer barrier (WPOB) to be used in evaluating waste package 
performance. The WPOB is constructed of Alloy 22 (UNS N06022), a highly corrosion-resistant 
nickel-based alloy. The inner vessel of the waste package is constructed of Stainless Steel 
Type 316 (UNS S31600). Before it fails, the Alloy 22 WPOB protects the Stainless Steel 
Type 316 inner vessel from exposure to the external environment and any significant 
degradation. The Stainless Steel Type 316 inner vessel provides structural stability to the thinner 
Alloy 22 WPOB. Although the waste package inner vessel would also provide some 
performance for waste containment and potentially decrease the rate of radionuclide transport 
after WPOB breach before it fails, the potential performance of the inner vessel is far less than 
that of the more corrosion-resistant Alloy 22 WPOB. For this reason, the corrosion performance 
of the waste package inner vessel is conservatively ignored in this report and the total system 
performance assessment for the license application (TSPA-LA). Treatment of seismic and 
igneous events and their consequences on waste package outer barrier performance are not 
specifically discussed in this report, although the general and localized corrosion models 
developed in this report are suitable for use in these scenarios. The localized corrosion processes 
considered in this report are pitting corrosion and crevice corrosion. Stress corrosion cracking is 
discussed in Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, 
and the Stainless Steel Structural Material (BSC 2004 [DIRS 169985]). 
The waste package outer barrier general corrosion model (developed in this report) is to be used 
by downstream waste package degradation analyses to evaluate the extent of WPOB degradation 
by general corrosion under repository environmental conditions over the regulatory performance 
period (10,000 years after permanent closure). The waste package outer barrier general 
corrosion model considers several submodels, which account for dry oxidation, aqueous general 
corrosion, the effects of aging and phase instability, and microbially influenced corrosion (MIC). 
The purpose of the waste package outer barrier localized corrosion model is to be used by 
downstream waste package degradation analyses to evaluate the extent of WPOB degradation by 
localized corrosion under the expected repository environmental conditions over the regulatory 
performance period. The submodels included in the waste package outer barrier localized 
corrosion model are the crevice repassivation potential, long-term corrosion potential, and 
crevice corrosion propagation models. The analyses and models developed in this report are 
used by the waste package degradation analyses for TSPA-LA and are prepared in accordance 
with Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form 
and Waste Package (BSC 2004 [DIRS 171583]). 
The following scientific analyses or models reports provide direct or indirect inputs to this 
report: Abstraction of Drift Seepage, Aging and Phase Stability of Waste Package Outer Barrier, 
Engineered Barrier System: Physical and Chemical Environment Model, Environment on the 
Surfaces of the Drip Shield and Waste Package Outer Barrier, Evaluation of the Impact of 
Microbial Activities on Drift Chemistry, and Multiscale Thermohydrologic Model. This report 
provides direct or indirect inputs to the following scientific analyses or model reports: WAPDEG 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 1-2 October 2004 
Analysis of Waste Package and Drip Shield Degradation, FEPs Screening of Processes and 
Issues in Drip Shield and Waste Package Degradation, and Total System Performance 
Assessment Model/Analysis For License Application. 
Lists of data tracking numbers (DTNs) and their Q-status are included in the Document Input 
Reference System (DIRS) database report. 
1.1 BACKGROUND ON ALLOY 22 
Alloy 22 (UNS N06022) is the reference material for construction of the outer barrier of the 
waste package. This alloy consists, by weight, of 20.0 to 22.5% chromium, 12.5 to 14.5% 
molybdenum, 3.5% tungsten, 2.0 to 6.0% iron, 2.5 to 2.5% (maximum) cobalt, and balance 
nickel (ASTM B 575-94 1994 [DIRS 100497]). Other impurity elements include phosphorus, 
silicon, sulphur, manganese, and vanadium (CRWMS M&O 1999 [DIRS 102933]; 
Treseder et al. 1991 [DIRS 110250]). The unusual localized corrosion resistance of Alloy 22 is 
mainly due to additions of molybdenum and chromium. Addition of these alloying elements to 
nickel alloys has been proven to significantly improve the resistance to localized corrosion of 
nickel alloys (Hack 1983 [DIRS 105750]; ASM International 1987 [DIRS 133378], pp. 641 
to 657). The oxides of these elements are very stable at low pH values making Alloy 22 highly 
resistant to localized corrosion. High repassivation potentials, an indication of high resistance to 
localized corrosion, for Alloy 22 have been observed by some investigators (Gruss et al. 1998 
[DIRS 100893]; Rebak et al. 2002 [DIRS 162237]), and others have found very low corrosion 
rates in crevice corrosion susceptibility testing solutions containing 10 weight percent FeCl3 
(Gdowski 1991 [DIRS 100859], Section 3.0; Haynes International 1997 [DIRS 100896]; Haynes 
International 1997 [DIRS 100897]). Furthermore, no localized corrosion attack of Alloy 22 has 
been seen in crevices exposed to concentrated solutions (similar to those relevant to the 
repository) conducted in the Yucca Mountain Project (YMP) Long Term Corrosion Test Facility 
(LTCTF) (Estill 1998 [DIRS 117697]). Test media used in this facility include simulated 
acidified water (SAW), simulated dilute water (SDW), and simulated concentrated water (SCW). 
Table 6-3 provides compositions of these solutions. 
1.2 RANGES OF MODEL APPLICATION 
Treatment of seismic and igneous events and their consequences on waste package outer barrier 
performance are not specifically discussed in this report, although the general and localized 
corrosion models developed in this report are suitable for use in these scenarios. Dry oxidation of 
the WPOB has an insignificant impact on the waste package performance (Section 6.4.2). 
Therefore, this degradation mode is not included in the waste package degradation analysis. The 
effects of thermal aging and phase instability are not included in the waste package degradation 
analysis because thermal aging and phase instability processes are not relevant under the thermal 
conditions in the repository (BSC 2004 [DIRS 169983], Section 8). 
The waste package outer barrier general corrosion model is applied when a stable aqueous water 
film exists on the waste package surface (Section 6.4.3.4). The general corrosion model 
(Section 6.4.3.4) was developed in this report using data in both mixed ionic environments and 
data from simple salt solutions including highly concentrated chloride brines and chloride brines 
containing nitrate ions. In Section 7.2, the general corrosion model is validated against data 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 1-3 October 2004 
obtained at temperatures as high as 150C. Therefore, the general corrosion model should be 
applicable over all repository exposure environments. Microbially influenced corrosion (MIC) 
effects are applied when the relative humidity at the waste package surface is greater than 90 
percent (Section 6.4.5). 
The waste package surface may experience a wide range of exposure conditions during its 
service life. Crevices may be formed on the waste package surface at occluded regions such as 
in between the waste package and its supports and potentially beneath mineral scales, corrosion 
products, dust, rocks, and biofilms. The area between the layers of the waste packages also could 
be considered a creviced region after the outer layer is breached. The chemical environment in a 
creviced region may be more severe than the near field environment due to hydrolysis of 
dissolved metals in the creviced region. Metal ion hydrolysis can lead to the accumulation of 
hydrogen ions and a corresponding decrease in pH. Electromigration of chloride ions (and other 
anions) into the crevice must occur to balance the charge within the creviced region (Jones 1992 
[DIRS 169906], Chapter 7). In this report, the dominant form of localized corrosion is 
conservatively assumed to be crevice corrosion (Assumption 5.3) as opposed to pitting corrosion, 
which occurs on boldly exposed surfaces. 
The empirical correlations used in the waste package outer barrier localized corrosion initiation 
model for the long-term corrosion potential (Ecorr) and crevice repassivation potential (Ercrev) are 
expressed as functions of temperature, pH, chloride ion concentration, and nitrate ion 
concentration (Sections 6.4.4.3 and 6.4.4.5). Based on the range of environmental conditions in 
which the input data were obtained (Appendices V, VI, VII, and VIII) and the model validation 
activities (Sections 7.2.2 and 7.2.3), implementation of the waste package outer barrier localized 
corrosion initiation model can be summarized as follows. 
Localized corrosion (like general corrosion) requires the presence of a liquid water film on the 
waste package surface. To implement the waste package outer barrier localized corrosion 
initiation model, the following criteria are applied in a stepwise fashion: 
1. If aqueous brine chemistry causes the initiation of localized corrosion, then localized 
corrosion continues to propagate regardless of changes in the bulk chemical exposure 
environment. This is a conservative modeling assumption because no detailed model 
of the chemistry evolution of the crevice solution is available at this time. 
2. If the exposure temperature exceeds 160C and a water film is present on the waste 
package surface, then localized corrosion initiates. 
Localized corrosion initiated as a result of this criterion is reevaluated in accordance 
with Criterion 3 (below) when the exposure temperature drops below 160C. 
3. If the exposure temperature exceeds 120C, but is less than or equal to 160C then, 
a) If the nitrate-to-chloride ion ratio is 0.5 (or greater), no localized corrosion will 
occur, or 
b) If the nitrate-to-chloride ion ratio is less than 0.5, then localized corrosion initiates 
and continues to propagate regardless of changes in the bulk chemical exposure 
environment (Criterion 1). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 1-4 October 2004 
4. If the exposure temperature is greater than or equal to 20C, and less than or equal to 
120C, then the empirical correlations for the long-term corrosion potential (Ecorr) and 
crevice repassivation potential (Ercrev) (Sections 6.4.4.3 and 6.4.4.5) are evaluated in 
accordance with the following implementation rules. If localized corrosion is 
determined to initiate, then localized corrosion continues to occur regardless of 
changes in the bulk chemical exposure environment (Criterion 1). 
a) If the nitrate-to-chloride ion ratio in the environment exceeds 0.5, 
then evaluate Ercrev and Ecorr at a nitrate-to-chloride ion ratio of 0.5. 
b) If the molality of chloride ion in the environment exceeds 36 molal, 
then evaluate Ercrev and Ecorr at a molality of chloride ion of 36 molal. 
If the molality of chloride ion is less than 0.001 molal, 
then evaluate Ercrev and Ecorr at a molality of chloride ion of 0.001 molal. 
c) If the molality of nitrate ion in the environment exceeds 18 molal, 
then evaluate Ercrev and Ecorr at a molality of nitrate ion of 18 molal. 
If the molality of nitrate ion is less than 0.001 molal, 
then Ercrev = o
rcrev E (i.e., the crevice repassivation potential in the absence 
of nitrate ions) and evaluate Ecorr at a molality of nitrate ion of 0.001 
molal. 
d) If the pH in the environment exceeds 10.9, 
then evaluate Ercrev and Ecorr at a pH of 10.9. 
If the pH in the environment is less than 2.8, 
then initiate localized corrosion. 
Nitrate ions inhibit localized corrosion initiation (Section 6.4.4.3). Carbonate and sulfate ions 
have an inhibitive effect on localized corrosion. Because the model only accounts for nitrate 
ions, model results for solutions with significant amounts of other potentially inhibitive ions in 
addition to nitrate ions are conservative. 
1.3 BARRIER CAPABILITIES 
10 CFR 63 [DIRS 156605] defines a barrier as any material, structure, or feature that, for a 
period to be determined by NRC, prevents or substantially reduces the rate of movement of water 
or radionuclides from the Yucca Mountain repository to the accessible environment, or prevents 
the release or substantially reduces the release rate of radionuclides from the waste. 
10 CFR 63.102 (h) [DIRS 156605] and 10 CFR 63.113 (a) [DIRS 156605] require the repository 
system to include multiple barriers, natural and engineered. The capability of a barrier is defined 
by its ability to achieve one or more of the functions described above (i.e., the extent to which it 
can prevent or delay the movement of water or radionuclides, or prevent or reduce the 
radionuclide release rate from the waste package). 
In this document, the barrier considered is the waste package with particular emphasis on the 
performance of the waste package outer barrier. The waste package barrier contributes to waste 
isolation by keeping water away from the waste for its lifetime and, when breached, by reducing 
the contact of water with the waste and radionuclide release rate from the waste. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 2-1 October 2004 
2. QUALITY ASSURANCE 
The Yucca Mountain Quality Assurance (QA) program applies to the development of this 
technical product. Technical Work Plan for: Regulatory Integration Modeling and Analysis of 
the Waste Form and Waste Package (BSC 2004 [DIRS 171583]) determined this activity is 
subject to Quality Assurance Requirements and Description (QARD) (DOE 2004 
[DIRS 171539]) requirements. All waste package configurations have been determined to be 
important to waste isolation in accordance with AP-2.22Q and, therefore, are classified as Safety 
Category (SC) in Q-List (BSC 2004 [DIRS 168361], Appendix A; BSC 2004 [DIRS 170992]). 
The inputs to this report were documented according to AP-3.15Q, Managing Technical Product 
Inputs. The methods used to control the electronic management of data as required by 
AP SV.1Q, Control of the Electronic Management of Information, were accomplished in 
accordance with the technical work plan (BSC 2004 [DIRS 171583]). The process for control of 
the electronic management of information on evaluation of work activities, processes, or process 
functions outlined in Section 5.0 of AP-SV.1Q was followed to ensure accuracy, completeness, 
and security of information and data used in preparation of this report. Examples of process 
controls mentioned in AP-SV.1Q are: (a) access to the information contained on personal 
computer is password protected; (b) secured backup copies are appropriately labeled and stored 
before changes are made and kept until the changes are confirmed and correct; (c) physical 
electronic media (tape, diskette, CD-ROM, etc.) are appropriately labeled; and (d) for 
nonphysical electronic media, transport mechanisms can be e-mail, TCP/IP, NetBios, etc. and 
methods of receipt verification may include visual inspection, transmission verification settings, 
check sums, application information integrity check, etc. 
This document is prepared in accordance with AP-SIII.10Q, Models, and reviewed in accordance 
with AP-2.14Q, Document Review. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 2-2 October 2004 
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General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 3-1 October 2004 
3. USE OF SOFTWARE 
Microsoft Excel 97 SR-2, bundled with Microsoft Office 1997, is a commercial off-the-shelf 
software program used in this report. The Excel computations performed in this report use only 
standard built-in functions and are documented in sufficient detail to allow an independent 
technical reviewer to reproduce or verify the results by visual inspection or hand calculation 
without recourse to the originator (Sections 6.4.3 to 6.4.6, and the Excel files included in the 
output DTNs: MO0409MWDULCMW.000 and MO0409MWDUGCMW.000). Therefore, use 
of this software is not subject to LP-SI.11Q-BSC, Software Management. Microsoft Excel 97 
SR-2 is appropriate for this application as it offers the mathematical and graphical functionality 
necessary to perform and document the numerical manipulations used in this report. Microsoft 
Excel 97 SR-2 was executed on an Optiplex GX260 Workstation (CRWMS M&O tag 152849, 
located in the Summerlin Offices, Las Vegas, Nevada) equipped with the Windows 2000 
operating system. 
Mathcad version 11.1 is a commercial off-the-shelf software program used in this model report. 
The Mathcad computations performed in this report use only standard functions and are 
documented in sufficient detail to allow an independent technical reviewer to reproduce or verify 
the results by visual inspection or hand calculation without recourse to the originator 
(Sections 6.4.3 and 6.4.4, and the Mathcad worksheet files included in the output 
DTNs: MO0409MWDULCMW.000 and MO0409MWDUGCMW.000). Therefore, use of this 
software is not subject to LP-SI.11Q-BSC, Software Management. This software is appropriate 
for this application as it offers the mathematical and graphical functionality necessary to perform 
and document the numerical manipulations used in this report. Mathcad version 11.1 was 
executed on an Optiplex GX260 Workstation (CRWMS M&O tag 152849, located in the 
Summerlin Offices, Las Vegas, Nevada) equipped with the Windows 2000 operating system. 
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ANL-EBS-MD-000003 REV 02 3-2 October 2004 
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ANL-EBS-MD-000003 REV 02 4-1 October 2004 
4. INPUTS 
This section documents input data and parameters used in the models and analyses in this report. 
This section also documents inputs from other models or analyses used in this report. Criteria 
directly applicable to the analyses or models in this report are identified, and a list of the 
applicable codes and standards used in the analyses or models in this report is provided. 
4.1 DIRECT INPUT 
Inputs to this report are tracked in accordance with AP-SIII.10Q, Models, and AP-3.15Q, 
Managing Technical Product Inputs. The data used to develop the models in this report are not 
used to validate the models developed in this report. 
4.1.1 Data 
Table 4-1 lists the input data used in the analyses or models documented in this report, and 
identifies the DTNs and specific sections where the data were used. Additional details of the 
input data are described in the following sections. The test procedures for the various 
electrochemical corrosion tests that were employed to generate the input data documented in this 
section are summarized in Appendix I, along with a summary for the test conditions and 
parameters. The electrochemical corrosion tests summarized in Appendix I include polarization 
resistance and cyclic potentiodynamic polarization (CPP) tests. The long-term open-circuit 
potential tests are summarized in Section 6.4.4.4. A summary of the test procedures for the 
weight-loss measurements of the 5-year samples from the Long-Term Corrosion Test Facility 
(LTCTF) is given in Section 6.4.3.1. The treatment of input data uncertainty is addressed in the 
data analysis and model development throughout Section 6.4. 
ANL-EBS-MD-000003 REV 02 4-2 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
Table 4-1. Summary of All Input Data Used in the Analyses and Models 
Data Name Data Source DTN Data Use in This 
Report 
Oxide Layer on Alloy 22 Formed in Air Waste Package Materials Testing LL030406412251.045 [DIRS 163469] Section 6.4.2 
Oxide Layer on Alloy 22 Formed in Mixed Salt 
Environment 
Andresen et al. 2003 
[DIRS 170360], Section 3.0 N/A  Vendor Data-Qualified Section 6.4.1 
Measured pH of Solutions from Long-Term 
Open-Circuit Potential Measurements Waste Package Materials Testing LL031001023121.035 [DIRS 170502] 
LL040402212251.084 [DIRS 170097] 
Sections 6.4.4, 7.2.4, 
Appendix V 
Molal Concentrations of Salt Solutions Used in 
Various Electrochemical Tests Waste Package Materials Testing LL030703723121.031 [DIRS 164184] 
LL031001023121.035 [DIRS 170502] 
Sections 6.4.4, 7.2.3, 
Appendices V, VI, and 
VII 
Alloy 22 Weight-Loss Data of Crevice and 
Weight-Loss Specimens After Five Year 
Exposure in the LTCTF 
Waste Package Materials Testing LL030412512251.057 [DIRS 163712] Section 6.4.3, 
Appendices II and III 
Polarization Resistance Data for Temperature 
Effect Waste Package Materials Testing 
LL030309512251.042 [DIRS 163455], 
LL030502212251.063 [DIRS 163456], 
LL030409812251.054 [DIRS 164185] 
Section 6.4.3, 
Appendix IV 
Polarization Resistance Data for Weld Effect Waste Package Materials Testing 
LL030309512251.042 [DIRS 163455], 
LL030502212251.063 [DIRS 163456], 
LL030409812251.054 [DIRS 164185] 
Sections 6.4.3 and 
6.4.6, Appendix IV 
Polarization Resistance Data for Aging Effect Waste Package Materials Testing 
LL030309512251.042 [DIRS 163455], 
LL030502212251.063 [DIRS 163456], 
LL030409812251.054 [DIRS 164185] 
Sections 6.4.3 and 
6.4.6, Appendix IV 
Long-Term Open-Circuit Potential Measurement 
Data in Various Solutions at Different 
Temperatures 
Waste Package Materials Testing 
LL020711612251.017 [DIRS 161204], 
LL040402112251.083 [DIRS 170283], 
LL040402212251.084 [DIRS 170097], 
Section 6.4.4 and 
Appendix V 
Cyclic Potentiodynamic Polarization 
Measurement Data in Chloride-Containing 
Solutions with Varying Nitrate Ion Concentrations 
at Different Temperatures 
Waste Package Materials Testing 
LL030409512251.051 [DIRS 163462], 
LL030309512251.042 [DIRS 163455], 
LL030502212251.063 [DIRS 163456], 
LL030409812251.054 [DIRS 164185], 
LL021105112251.022 [DIRS 161138], 
LL030400112251.043 [DIRS 163466], 
LL030406212251.044 [DIRS 163467], 
LL040402212251.084 [DIRS 170097] 
Section 6.4.4, 
Appendix VI, Appendix 
VIII 
Alteration of Corrosion Rates Associated with 
Microbial Activity Waste Package Materials Testing LL991203505924.094 [DIRS 138343] Section 6.4.5 
Relative Humidity Threshold for MIC BSC 2004 [DIRS 169991], 
Section 7.1 N/A - Data-Qualified Section 6.4.5 
ANL-EBS-MD-000003 REV 02 4-3 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
Data Name Data Source DTN Data Use in This 
Report 
Density of Alloy 22 Haynes International 1997 
[DIRS 100896], p. 13 N/A  Vendor Data-Qualified Section 6.4.3, 
Appendix I 
Equivalent Weight of Alloy 22 ASTM G 102-89 1989 
[DIRS 163908] N/A  Established Fact Appendix I 
Alloy 22 Corrosion Rate in 10% Ferric Chloride 
Solution 
Haynes International 1997 
[DIRS 100897], p. 8 N/A  Vendor Data-Qualified Section 6.4.4 
Alloy 22 Corrosion Rates in Concentrated 
Hydrochloric Acid 
Haynes International 1997 
[DIRS 100896], p. 12 N/A  Vendor Data-Qualified Section 6.4.4 
pH of 5 M CaCl2 solutions Ilevbare 2003 [DIRS 171329], 
p. 141 N/A  Data Qualified Section 6.4.4, 
Appendices IV and VI 
Faraday Constant Lide 1991 [DIRS 131202], Table 1, 
p. I-1 N/A  Established Fact Appendix I 
Crevice Repassivation Potentials of Alloy 22 in 
NaCl Solutions at Varying Temperatures 
Brossia et al. 2001 [DIRS 159836], 
Table A-1 Data Internally Qualified Section 4.1.2 
Section 6.4.4 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-4 October 2004 
4.1.1.1 Passive Film Characterization 
Characterization of the passive film formed on Alloy 22 in various exposure environments is 
used to provide a technical basis for constructing the conceptual model of the structure and 
composition of the film. This information is also used as an aid in interpreting corrosion data 
and their implications on corrosion behavior. Table 4-2 lists the sources of the passive film 
characterization data and the associated DTNs (if applicable). Because these input data are used 
in a qualitative manner, no quantitative analysis for data uncertainty will be performed. 
Table 4-2. Alloy 22 Passive Film Characterization Data 
Data Name Data Source DTN 
Data Use in 
This Report 
Oxide Layer on Alloy 22 Formed in Air Waste Package Materials 
Testing 
LL030406412251.045 
[DIRS 163469] Section 6.4.2 
Oxide Layer on Alloy 22 Formed in Mixed 
Salt Environment 
Andresen et al. 2003 
[DIRS 170360], Section 3.0 
N/A  Vendor Data- 
Qualified Section 6.4.1 
4.1.1.2 Corrosion Test Solution Composition 
Models and analyses of Alloy 22 degradation consider exposure conditions as well as 
metallurgical conditions (i.e., base metal versus weld, aged versus non-aged, etc.). Exposure 
condition parameters important to corrosion are temperature and composition of the solution 
contacting the metal. The species that significantly affect metal corrosion are hydrogen ions 
(e.g., pH), halide ions (e.g., chloride ions), corrosion-inhibiting ions (e.g., nitrate and sulfate 
ions), and dissolved oxygen. The compositions of the solutions employed in various corrosion 
tests for Alloy 22 are input to the Alloy 22 corrosion analyses and models. Table 4-3 lists the 
source of the corrosion test solution compositions and the associated DTNs. Because a single 
concentration measurement for each species for each solution condition (or each test condition) 
is reported and little uncertainty is expected in the measurements, no discussion or analysis of 
input data uncertainty is necessary. 
Table 4-3. Compositions of Solutions Employed in Various Corrosion Tests of Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Molal Concentrations of Salt Solutions 
Used in Various Electrochemical Tests 
Waste Package 
Materials Testing 
LL030703723121.031 [DIRS 164184] 
LL031001023121.035 [DIRS 170502] 
Sections 
6.4.4, 7.2.3; 
Appendices 
V, VI, and 
VII 
4.1.1.3 Long-Term Corrosion Weight-Loss Data 
Alloy 22 specimens with differing configurations and material conditions have been tested in the 
Projects Long-Term Corrosion Test Facility (LTCTF). Five-year weight-loss data are used to 
calculate the general corrosion rates used in the waste package outer barrier general corrosion 
model documented in this report (DTN: LL030412512251.057 [DIRS 163712]). The solution 
chemistries used in the LTCTF are listed in Table 6-3. The 5-year weight-loss data and the 
calculated rates are listed in Appendices II and III. The calculated general corrosion rates 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-5 October 2004 
slightly differ from those in the input DTN due to differences in the number of significant digits 
used. Uncertainty in these data is analyzed, quantified, and propagated into the general corrosion 
model (Section 6.4.3.3). Table 4-4 lists the data source and associated DTNs for the 5-year 
Alloy 22 weight-loss data. 
Table 4-4. Long-Term Corrosion Weight-Loss Data for Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Alloy 22 Weight-Loss Data of Crevice and 
Weight-Loss Specimens After Five Year 
Exposure in the LTCTF 
Waste Package 
Materials Testing 
LL030412512251.057 
[DIRS 163712] 
Section 6.4.3 
Appendices II 
and III 
4.1.1.4 Polarization Resistance Data 
The polarization resistance technique was used to measure the corrosion rate of Alloy 22 under 
various testing conditions. The corrosion rates measured by the technique are to be used for 
comparative analysis of the corrosion behavior under a wide range of test conditions. They are 
not used to obtain the absolute values of the corrosion rates. The polarization resistance data 
were used to determine the temperature dependence of the general corrosion rate (Section 6.4.3) 
and to evaluate the effect of welding and thermal aging on Alloy 22 corrosion rates 
(Section 6.4.6). The variables in the tests are exposure condition (e.g., temperature and water 
chemistry), sample configuration (e.g., crevice, rod, prism and disc), and metallurgical condition 
(e.g., mill annealed, as-welded, and as-welded plus thermally aged). 
Table 4-5 lists the sources of the polarization resistance data of Alloy 22 that were used to 
analyze the effect of the exposure and metallurgical condition on the WPOB corrosion 
performance in the repository. The input data are listed in Appendix IV. The range of the test 
conditions for the polarization resistance data include temperature from 45C to 170C, chloride 
concentration from 1 M to 18 M, and nitrate concentration from zero to 2 M. Each of the DTNs 
listed in the table also contains the 24-hour open-circuit corrosion potential (or 24-hour corrosion 
potential) data and the cyclic potentiodynamic polarization (CPP) data. Details of the 
electrochemical testing techniques to measure the above corrosion properties of Alloy 22 are 
described in Appendix I. Uncertainty in the data was analyzed, quantified, and propagated into 
the model (Section 6.4.3.4). 
The polarization resistance data for the electrolytes containing NaF and oxalic acid were not 
included in the quantitative model analysis because these chemical environments are not 
expected to be relevant to the repository conditions. The NaF data set includes pure 1 M NaF 
solutions and 0.5 M NaF + 0.5 M NaCl solutions at 60C and 90C. The seepage and dust 
deliquescence chemistries predicted in the repository are chloride dominated (BSC 2004 
[DIRS 169860], Figures 6.13-2 through 6.13-12 and 6.13-18 through 6.13-23) meaning that 
solutions of pure NaF and solutions with one to one ratios of NaF and NaCl are not 
representative of the repository exposure environment. The testing solutions used in long-term 
weight-loss measurements at 60C and 90C include Simulated Concentrated Water (SCW, 
Table 6-3), which contains about 1,400 mg/L fluoride ions and 6,700 mg/L chloride ions. 
Therefore, the effects of fluoride ions on general corrosion are included in the general corrosion 
model developed in this report. The oxalic acid data set includes 0.01 M, 0.1 M, and 1 M oxalic 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-6 October 2004 
acid solutions at 30C, 60C, and 90C. The pH of these solutions varies from about 0.5, for 1 
M oxalic acid solution, to about 2.2, for a 0.01 M oxalic acid solution. Not only are these pH 
values lower than any in the repository, oxalic acid is not reported to be present in the repository 
environment as outlined in Engineered Barrier System: Physical and Chemical Environment 
(BSC 2004 [DIRS 169860], Figures 6.13-2 through 6.13-12 and 6.13-18 through 6.13-23). 
The data for the multiple crevice assembly (MCA) samples with the surface condition labeled as 
As Received (AR) were not included in the model analysis in this report. This was because the 
surface of the edges of those MCA samples may have been damaged and contaminated with 
some active materials during the sample preparation. The active materials caused abnormal 
signals in the electrochemical corrosion tests under the action of externally applied potentials. 
Since the waste packages will not have damaged areas subjected to externally applied potentials 
in the repository, it is appropriate not to use these data in model development. Details of the 
conditions of those MCA samples are provided in scientific notebooks associated with the DTNs 
used. 
Table 4-5. Polarization Resistance Measurement Data for Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Polarization Resistance Data for Temperature 
Effect 
Waste Package 
Materials Testing 
LL030309512251.042 
[DIRS 163455], 
LL030502212251.063 
[DIRS 163456], 
LL030409812251.054 
[DIRS 164185] 
Section 6.4.3, 
Appendix IV 
Polarization Resistance Data for Weld Effect Waste Package 
Materials Testing 
LL030309512251.042 
[DIRS 163455], 
LL030502212251.063 
[DIRS 163456], 
LL030409812251.054 
[DIRS 164185] 
Sections 
6.4.3 and 
6.4.6, 
Appendix IV 
Polarization Resistance Data for Aging Effect Waste Package 
Materials Testing 
LL030309512251.042 
[DIRS 163455], 
LL030502212251.063 
[DIRS 163456], 
LL030409812251.054 
[DIRS 164185] 
Sections 
6.4.3 and 
6.4.6, 
Appendix IV 
4.1.1.5 Long-Term Open-Circuit Corrosion Potential Data 
The open-circuit corrosion potential (also referred to as corrosion potential (Ecorr)) is an 
important corrosion property of a metal/alloy. The corrosion potential of a metal or alloy may be 
affected by the sample configuration (e.g., boldly exposed and crevice), metallurgical condition 
(e.g., mill annealed, as-welded and aged), and exposure environment. For a given exposure 
environment, it can change over time depending mostly on the kinetics of electrochemical 
reactions involved. In this report, the corrosion potentials, along with the critical potentials for 
localized corrosion discussed in Section 6.4.4.3, were used for the localized corrosion initiation 
model. Section 6.4.4.3 provides details of the localized corrosion initiation model. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-7 October 2004 
As stated above, the corrosion potential may change over time, eventually approaching a steadystate 
value (Section 6.4.4.4). The initial changes can be significant, depending on the exposure 
environment and the sample surface conditions. Therefore, the long-term steady-state corrosion 
potentials were used for the corrosion potential model of Alloy 22. The test conditions varied in 
the long-term corrosion potential measurements are exposure environment (temperature and 
water chemistry), sample geometry (U-bend and rod), and metallurgical conditions (mill 
annealed and as-welded). Table 4-6 lists the data sources for the long-term open-circuit 
corrosion potential data of Alloy 22 for a range of exposure environments and metallurgical 
conditions. The range of the test conditions for the long-term open-circuit corrosion potential 
data include temperatures from 25C to 120C, pH values from 2.8 to 10.9, chloride 
concentration from very dilute to about 12.6 m (moles/kg water), and nitrate concentration from 
zero to 2.6 m. 
Because of measurement noise in the long-term corrosion potentials, the average of the measured 
readings for the final week of exposure was used in the model. The acquired Ecorr data is 
contained in two separate DTNs: LL020711612251.017 [DIRS 161204] and 
LL040402112251.083 [DIRS 170283]. DTN: LL020711612251.017 [DIRS 161204] has the 
acquired data up to September 3, 2002, and the data acquired beyond that date is reported in 
DTN: LL040402112251.083 [DIRS 170283]. However, if a cell was terminated before 
September 3, 2002 (e.g., Cell 7), its data are reported only in DTN: LL020711612251.017 
[DIRS 161204], and if testing was started after that date (Cells 16 and higher), the acquired data 
is reported only in DTN: LL040402112251.083 [DIRS 170283]. The final average values of 
Ecorr for each specimen from DTNs: LL040402112251.083 [DIRS 170283] and 
LL020711612251.017 [DIRS 161204] are listed in DTN: LL040402212251.084 
[DIRS 170097]. Only the final Ecorr data in DTN: LL040402212251.084 [DIRS 170097], 
corresponding to testing times of 328 days and longer, were used for the development of the 
model in Section 6.4.4.5. Analyses in Section 6.4.4.4 indicate Ecorr values are reasonably stable 
for use in the model after 328 days. The data that were obtained accordingly are listed in 
Appendix V. Uncertainty in the data was analyzed, quantified, and propagated into the corrosion 
potential model. Details of the uncertainty analysis are documented in Section 6.4.4.5. 
The long-term corrosion potential data for the electrolytes containing NaF and oxalic acid 
(Cells 11 and 12) reported in DTN: LL020711612251.017 [DIRS 161204] were not included in 
the quantitative model analysis because these chemical environments are not relevant to the 
repository conditions. The NaF data set includes pure 1 M NaF solutions at 90C (Cell 12). The 
seepage and dust deliquescence chemistries are chloride dominated (BSC 2004 [DIRS 169860], 
Figures 6.13-2 through 6.13-12 and 6.13-18 through 6.13-23) meaning that solutions of pure NaF 
solutions are not representative of the repository exposure environments. The testing solutions 
used in long-term corrosion potential measurements at 60C and 90C include Simulated 
Concentrated Water (SCW, Table 6-3), which contains about 1,400 mg/L fluoride ions and 
6,700 mg/L chloride ions. Therefore, the effects of fluoride ions are included in the long-term 
corrosion potential model developed in this report. The oxalic acid data set includes 0.1 M 
oxalic acid solution at 30C (Cell 11). The pH of this solution is about 1.5. Not only is this pH 
value lower than any in the repository, oxalic acid is not present in the repository environment as 
outlined in Engineered Barrier System: Physical and Chemical Environment (BSC 2004 
[DIRS 169860], Figures 6.13-2 through 6.13-12 and 6.13-18 through 6.13-23). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-8 October 2004 
Table 4-6. Long-Term Open-Circuit Corrosion Potential Measurement Data for Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Long-Term Open-Circuit Potential Measurement Data 
in Aged LTCTF Solutions at Different Temperatures 
Waste Package 
Materials Testing 
LL020711612251.017 
[DIRS 161204] 
LL040402112251.083 
[DIRS 170283] 
LL040402212251.084 
[DIRS 170097] 
Section 6.4.4, 
Appendix V 
Long-Term Open-Circuit Potential Measurement Data 
in Fresh LTCTF Solutions at Different Temperatures 
Waste Package 
Materials Testing 
LL020711612251.017 
[DIRS 161204] 
LL040402112251.083 
[DIRS 170283] 
LL040402212251.084 
[DIRS 170097] 
Section 6.4.4, 
Appendix V 
Long-Term Open-Circuit Potential Measurement Data 
in BSW at Different Temperatures 
Waste Package 
Materials Testing 
LL020711612251.017 
[DIRS 161204] 
LL040402112251.083 
[DIRS 170283] 
LL040402212251.084 
[DIRS 170097] 
Section 6.4.4, 
Appendix V 
Long-Term Open-Circuit Potential Measurement Data 
in CaCl2 + Ca(NO3)2 Solution with Varying Chloride 
and Nitrate Concentration Ratios at Different 
Temperatures 
Waste Package 
Materials Testing 
LL020711612251.017 
[DIRS 161204] 
LL040402112251.083 
[DIRS 170283] 
LL040402212251.084 
[DIRS 170097] 
Section 6.4.4, 
Appendix V 
4.1.1.6 Cyclic Potentiodynamic Polarization Data 
The cyclic potentiodynamic polarization (CPP) technique was used to measure a critical potential 
(Ecritical) for localized corrosion (pitting or crevice corrosion, or both) of Alloy 22 for a range of 
exposure conditions relevant to the repository. CPP tests were carried out for a variety of 
exposure environments (temperature and water chemistry), sample configurations (crevice or 
boldly exposed), and metallurgical conditions (mill annealed, as-welded, or aged). Table 4-7 
lists the sources of the CPP data of Alloy 22 for a wide range of exposure and metallurgical 
conditions 
The input DTNs listed in the table also contain other electrochemical measurement data such as 
24-hour open-circuit corrosion potentials (or 24-hour corrosion potentials) and polarization 
resistance measurements (Section 4.1.1.4). Details of the electrochemical testing techniques 
used to measure the above corrosion properties of Alloy 22 are described in Appendix I. 
The sources of the data and associated DTNs are also listed in the table. 
The CPP data for the electrolytes containing NaF and oxalic acid reported in 
DTNs: LL030309512251.042 [DIRS 163455] and LL030502212251.063 [DIRS 163456], were 
not included in the quantitative model analysis because these chemical environments are not 
relevant to the repository. The NaF data set includes pure 1 M NaF solutions and 0.5 M NaF + 
0.5 M NaCl solutions at 60C and 90C. The seepage and dust deliquescence chemistries 
predicted in the repository are chloride dominated (BSC 2004 [DIRS 169860], Figures 6.13-2 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-9 October 2004 
through 6.13-12 and 6.13-18 through 6.13-23), which means solutions of pure NaF and solutions 
with one to one ratios of NaF and NaCl are not representative of the repository exposure 
environments. The testing solutions used in the cyclic polarization measurements at 60C and 
90C include Simulated Concentrated Water (SCW, Table 6-3), which contains about 
1,400 mg/L fluoride ions and 6,700 mg/L chloride ions. Therefore, the effects of fluoride ions 
on general corrosion are included in the analyses in this report. The oxalic acid data set includes 
0.01 M, 0.1 M, and 1M oxalic acid solutions at 30C, 60C, and 90C. The pH of these solutions 
varies from about 0.5, for 1 M oxalic acid solution, to about 2.2, for a 0.01 M oxalic acid 
solution. Not only are these pH values lower than any expected in the repository, oxalic acid is 
not present in the repository environment as outlined in Engineered Barrier System: Physical 
and Chemical Environment (BSC 2004 [DIRS 169860], Figures 6.13-2 through 6.13-12 and 
6.13-18 through 6.13-23). 
The data for the multiple crevice assembly (MCA) samples with the surface condition labeled as 
As Received (AR) or as Edges Not Polished were not included in the quantitative model 
analysis of this model report. This was because the surface of the edges of those MCA samples 
may have been damaged or contaminated with some active materials during the sample 
preparation, or both. The MCA samples labeled AR did not have the edges properly polished, 
and this caused abnormal signals in the electrochemical corrosion tests under applied potentials. 
Table 4-7. Cyclic Potentiodynamic Polarization Measurement Data for Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Cyclic Potentiodynamic Polarization 
Measurement Data in Fresh 
Chloride-Containing Solutions with 
Varying Nitrate Ion Concentrations 
at Different Temperatures 
Waste Package 
Materials Testing 
LL030409512251.051 [DIRS 163462], 
LL030309512251.042 [DIRS 163455], 
LL030502212251.063 [DIRS 163456], 
LL030409812251.054 [DIRS 164185], 
LL021105112251.022 [DIRS 161138], 
LL030400112251.043 [DIRS 163466], 
LL030406212251.044 [DIRS 163467], 
LL040402212251.084 [DIRS 170097] 
Section 6.4.4, 
Appendices 
VI and VIII 
4.1.1.7 Crevice Repassivation Potential Data 
The localized corrosion conceptual model assumes that crevices form on the waste package 
surface in the repository (Assumption 5.3 and Section 6.4.4). Thus, crevice corrosion was 
conservatively taken as the representative form of localized corrosion on the WPOB 
(Assumption 5.3). The crevice repassivation potentials (Ercrev) from the CPP curves described in 
Section 4.1.1.6 were selected as the critical potentials for localized corrosion. As discussed in 
Section 6.4.4.1, the crevice repassivation potential is a conservative measure of the critical 
potential for localized corrosion initiation. Input DTN: LL030409512251.051 [DIRS 163462] 
documents the analyses for obtaining the crevice repassivation potentials from the CPP curves. 
The final set of data developed from the analyses are listed in the tables contained in the files 
with the file name beginning with "TSES" under the LL030409512251.051 TDMS directory 
of the DTN data package. Crevice repassivation potentials were also obtained from 
DTN: LL040402212251.084 [DIRS 170097]. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-10 October 2004 
Only the crevice (i.e., MCA) sample data were used for repassivation potential model analysis 
with the exception of the repassivation potential data for samples DEA598, DEA599, and 
DEA600 from DTN: LL030409812251.054 [DIRS 164185], which were disc samples exposed 
to high-chloride concentrations (12.6 to 20.8 m) and high temperatures (120C and 130C). 
These data were included to increase the data population for the model analysis and improve the 
predictive capability of the model. As discussed in Section 6.4.4.2, there are no significant 
differences in the repassivation potential between the two types of samples for these conditions. 
In addition, the MCA corrosion data that did not show occurrence of localized corrosion were 
conservatively excluded from the analysis, except when the nitrate-to-chloride ratio of the test 
solution was 0.50, in which case a repassivation potential of +600 mV versus (silver-silver 
chloride reference electrode scale) SSC was used (Section 6.4.4.1). Section 6.4.4.2 and 
DTN: LL030409512251.051 [DIRS 163462] provide details on the data screening analysis. The 
crevice repassivation potential data used in the analyses are listed in Appendices VI and VIII. 
Table 4-8 lists the sources of the crevice repassivation potential data of Alloy 22 used in the 
critical potential model analysis. Uncertainty in the data was analyzed, quantified, and 
propagated into the critical potential model. Details of the uncertainty analysis are documented 
in Section 6.4.4.3. 
Table 4-8. Crevice Repassivation Potential Data for Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Crevice Repassivation Potentials of Alloy 22 in NaCl 
and CaCl2 Solutions with Varying Nitrate 
Concentrations at Different Temperatures 
Waste Package 
Materials Testing 
LL030409512251.051 
[DIRS 163462] 
LL030409812251.054 
[DIRS 164185] 
LL040402212251.084 
[DIRS 170097] 
Section 6.4.4 
4.1.1.8 pH of 5 M CaCl2 Solution 
The pH values for some 5 M CaCl2 solutions in which data were obtained were not measured. In 
these cases, a value of 4.14 was used (Section 6.4.4 and Appendices IV and VI). This pH value 
was from the scientific notebook associated with DTN: LL030400112251.043 [DIRS 163466] 
(i.e., Ilevbare 2003 [DIRS 171329], p. 141). This datum is appropriate for its intended use 
because it was obtained under the Project quality assurance process. Table 4-9 lists the source of 
the pH value used for the 5 M CaCl2 solutions and where they are used in this report. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-11 October 2004 
Table 4-9. pH of 5 M CaCl2 Solutions 
Data Name Data Source DTN 
Data Use in This 
Report 
pH of 5 M CaCl2 solutions Ilevbare 2003 [DIRS 171329], p. 141 N/A  Data Qualified Section 6.4.4, 
Appendices IV and VI 
4.1.1.9 Microbially Influenced Corrosion 
Microbially influenced corrosion (MIC) is the contribution to the corrosion of a metal or alloy 
due to the presence or activity, or both, of microorganisms. Nickel-based alloys such as 
Alloy 22 are highly resistant to microbially influenced corrosion (Lian et al. 1999 
[DIRS 110238]). 
The effect of MIC on the WPOB corrosion is represented with a general corrosion enhancement 
factor applied when the exposure relative humidity exceeds 90 percent (BSC 2004 
[DIRS 169991], Section 7.1). Table 4-10 lists the source of the input data used to evaluate the 
MIC effect on the WPOB general corrosion rate. DTN: LL991203505924.094 [DIRS 138343] 
contains measurements for the corrosion potentials and corrosion rates of several engineering 
alloys, including Alloy 22, in the presence and absence of microbes relevant to the repository. 
The corrosion rates were obtained from the short-term polarization resistance tests. The MIC 
enhancement factor was determined from the comparative analysis of the corrosion rates of 
Alloy 22 samples in abiotic and biotic conditions. Uncertainty associated with the MIC 
enhancement factor is discussed in Section 6.4.5. The relative humidity threshold for MIC is 
based on analyses documented in Evaluation of the Impact of Microbial Activities on Drift 
Chemistry report (BSC 2004 [DIRS 169991], Section 7.1). In that report, it is noted that 
microbial activity is minimal when the activity of water (equivalent to the relative humidity 
fraction) falls below 0.90 and microbes have trouble thriving when the activity of water is less 
than 0.95 (BSC 2004 [DIRS 169991], Section 7.1). 
Table 4-10. Input Data for Microbially Influenced Corrosion of Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Alteration of Corrosion Rates Associated with 
Microbial Activity 
Waste Package 
Materials Testing 
LL991203505924.094 
[DIRS 138343] Section 6.4.5 
Relative Humidity Threshold for MIC 
BSC 2004 
[DIRS 169991], 
Section 7.1 
N/A-Data-Qualified Section 6.4.5 
4.1.1.10 Density of Alloy 22 and Faraday Constant 
The density of Alloy 22 (8.69 g/cm3) was used to calculate the general corrosion rates of 
Alloy 22 from the weight-loss measurements of the five-year samples from the LTCTF 
(Section 6.4.3) and for determination of corrosion rates from polarization resistance tests in 
Appendix I. The Faraday constant value (96,486 coulombs/mol) was used in this report to 
calculate the corrosion rates from the corrosion current measurements in Appendix I (Lide 1991 
[DIRS 131202], Table 1, p. I-1). Table 4-11 lists these data and their sources. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-12 October 2004 
Table 4-11. Density of Alloy 22 and Faraday Constant 
Data Name Data Source DTN 
Data Use in 
This Report 
Density of Alloy 22 Haynes International 1997 [DIRS 100896], p. 13 N/A  Vendor Data- 
Qualified 
Section 6.4.3; 
Appendix I 
Faraday Constant Lide 1991 [DIRS 131202], Table 1, p. I-1 N/A  Established Fact Appendix I 
4.1.1.11 Equivalent Weight of Alloy 22 
The equivalent weight for Alloy 22 (N06022) is calculated considering that the alloy dissolves 
stoichiometrically and depends on the valence of the dissolved elements. The equivalent weight 
of Alloy 22 is used in determining general corrosion rates from the polarization resistance data in 
Appendix I. Table 1 of ASTM G 102-89 (1989 [DIRS 163908]) presents several choices for the 
Alloy 22 equivalent weight. The actual choice of which equivalent weight to use has no impact 
on the analysis results presented in this report because only relative corrosion rates (e.g., between 
welded and nonwelded samples) are used, not their absolute values. The value of the equivalent 
weight used (23.28) was from Table 1 (column labeled Third) in ASTM G 102-89 
[DIRS 163908], Table 1. Table 4-12 lists the source of the equivalent weight of Alloy 22. 
Table 4-12. Equivalent Weight of Alloy 22 
Data Name Data Source DTN Data Use in This Report 
Equivalent Weight of Alloy 22 ASTM G 102-89 (1989 
[DIRS 163908]), Table 1 N/A  Established Fact Appendix I 
4.1.1.12 Localized Penetration Rates of Alloy 22 
Corrosion rates of Alloy 22 in aggressive solutions are used to represent the localized corrosion 
penetration rates of Alloy 22 in Section 6.4.4. Table 4-13 lists the source of these corrosion rates 
of Alloy 22. The localized corrosion penetration rate values used are listed in Table 6-9. 
Table 4-13. Localized Corrosion Penetration Rates of Alloy 22 
Data Name Data Source DTN 
Data Use in 
This Report 
Alloy 22 corrosion rate in 10% ferric 
chloride solution 
Haynes International 1997 
[DIRS 100897], p. 8 
N/A  Vendor Data- 
Qualified Section 6.4.4 
Alloy 22 corrosion rates in concentrated 
hydrochloric acid 
Haynes International 1997 
[DIRS 100896], p. 12 
N/A  Vendor Data- 
Qualified Section 6.4.4 
4.1.2 Other Model/Analyses Inputs 
An approach similar to that used for the Alloy 22 crevice repassivation potentials described in 
Section 4.1.1.7 was also used by the investigators at the Center for Nuclear Waste Regulatory 
Analyses (CNWRA) for the Nuclear Regulatory Commission (NRC) to obtain the crevice 
repassivation potentials for Alloy 22. The data were generated under CNWRA QA procedures 
and reported by Brossia et al. (2001 [DIRS 159836], Table A-1). On this basis, the data source is 
considered reliable and the personnel and organization generating the data operate under a QA 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-13 October 2004 
program compatible with specifications of Quality Assurance Requirements and Description 
(BSC 2004 [DIRS 171539]). In Section 6.4.4, sufficient discussion of the extent to which the 
data demonstrate the properties of interest, prior uses of the data, and comparison to 
corroborating data are presented. Therefore, the data are suitable for the specific application for 
which they are used in this report and are qualified for use within this technical product. The test 
environments for the reported data set are 0.005 M to 4 M chloride concentration and 80C 
to 150C. These data are also included in the critical potential model analysis and listed in 
Appendix VII. Table 4-14 lists the source of the CNWRA crevice repassivation potential data of 
Alloy 22 used in the critical potential model analysis. Uncertainty in the data was analyzed, 
quantified, and propagated into the critical potential model. Details of the uncertainty analysis 
are documented in Section 6.4.4.3. 
Table 4-14. Crevice Repassivation Potentials for Alloy 22 from Other Source 
Data Name Data Source DTN 
Data Use in 
This Report 
Crevice Repassivation Potentials of Alloy 22 
in NaCl Solutions at Varying Temperatures 
Brossia et al. 2001 
[DIRS 159836], Table A-1 
Data Internally 
Qualified Section 6.4.4 
4.2 CRITERIA 
The technical work plan (TWP) (BSC 2004 [DIRS 171583], Table 3-1) identified the following 
acceptance criteria (AC) based on the requirements mentioned in Project Requirements 
Document (Canori and Leitner 2003 [DIRS 166275]) and Yucca Mountain Review Plan, Final 
Report (NRC 2003 [DIRS 163274]): 
1. System Description and Demonstration of Multiple Barriers (NRC 2003 
[DIRS 163274], Section 2.2.1.1.3; Canori and Leitner 2003 [DIRS 166275]; 
PRD-002/T-014; PRD-002/T-016) 
Specific requirements involve identification of multiple barriers (natural and 
engineered), describing the capabilities of these barriers to isolate waste, and 
providing technical bases for capabilities descriptions consistent with the postclosure 
performance objectives. To comply with these requirements, the following 
acceptance criteria are identified: 
 AC1: Identification of Barriers is Adequate 
 AC2: Description of the Capability of Identified Barriers is Acceptable 
 AC3: Technical Basis for Barrier Capability is Adequately Presented. 
2. Degradation of Engineered Barriers (NRC 2003 [DIRS 163274], Section 2.2.1.3.1.3; 
Canori and Leitner 2003 [DIRS 166275], PRD-002/T-015) 
Specific requirements include describing deterioration or degradation of engineered 
barriers and modeling degradation processes using data for performance assessment, 
including total system performance assessment (TSPA). Consideration of 
uncertainties and variabilities in model parameters and alternative conceptual models 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-14 October 2004 
are also required. To fulfill these requirements, the following acceptance criteria are 
identified: 
 AC1: System Description and Model Integration are Adequate 
 AC2: Data are Sufficient for Model Justification 
 AC3: Data Uncertainty is Characterized and Propagated Through the Model 
Abstraction 
 AC4: Model Uncertainty is Characterized and Propagated Through the Model 
Abstraction 
 AC5: Model Abstraction Output is Supported by Objective Comparisons. 
The Yucca Mountain Review Plan Criteria are addressed in Section 8.4. 
4.3 CODES AND STANDARDS 
This section lists the codes and standards used in the model analyses documented in this report. 
4.3.1 Corrosion Degradation Analyses and Models 
 Standard Practice for Prediction of the Long-Term Behavior of Materials, Including 
Waste Forms, Used in Engineered Barrier Systems (EBS) for Geological Disposal of 
High-Level Radioactive Waste (ASTM C 1174-97 2002 [DIRS 105725]). 
4.3.2 Cyclic Polarization Measurements 
 Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic 
Polarization Measurements (ASTM G 5-94 1994 [DIRS 117479]) 
 Standard Test Method for Conducting Cyclic Potentiodynamic Polarization 
Measurements for Localized Corrosion Susceptibility of Iron-, Nickel-, or Cobalt-Based 
Alloys (ASTM G 61-86 1987 [DIRS 127897]) 
 Standard Practice for Making and Using U-Bend Stress-Corrosion Test Specimens 
(ASTM G 30-94 1994 [DIRS 137688]). 
4.3.3 General Corrosion Measurements 
 Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens 
(ASTM G 1-90 1999 [DIRS 103515]) 
 Standard Test Method for Conducting Potentiodynamic Polarization Resistance 
Measurements (ASTM G 59-97 1998 [DIRS 163907]) 
 Standard Practice for Conventions Applicable to Electrochemical Measurements in 
Corrosion Testing (ASTM G 3-89 1989 [DIRS 138911]) 
 Standard Practice for Calculation of Corrosion Rates and Related Information from 
Electrochemical Measurements (ASTM G 102-89 1989 [DIRS 163908]). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-15 October 2004 
4.3.4 Composition of Alloy 22 
 Standard Specification for Low-Carbon Nickel-Molybdenum-Chromium and Low- 
Carbon Nickel-Chromium-Molybdenum Steel Alloy Plate, Sheet, and Strip 
(ASTM B 575-94 1994 [DIRS 100497]). 
4.3.5 Standard Practice for Dealing with Outlying Observations 
 Standard Practice for Dealing with Outlying Observations (ASTM E 178-02 2002 
[DIRS 169968]). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 4-16 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 5-1 October 2004 
5. ASSUMPTIONS 
This section documents the assumptions used to perform analyses and model development and, if 
necessary, their abstractions for general corrosion and localized corrosion of the waste package 
outer barrier (WPOB) for the exposure conditions expected in the postclosure repository. Where 
necessary, additional details of the assumptions are described in the section(s) in which the 
analyses and models are documented. 
5.1 Assumption: Aqueous corrosion, including humid-air corrosion, general corrosion, and 
localized corrosion, is assumed to occur only if the relative humidity (RH) exceeds a 
threshold RH (RHthreshold). As discussed in Section 6.4.2, dry oxidation can occur at relative 
humidities below the threshold RH. Although no values for the threshold RH are presented 
in this report, the existence of a threshold RH is mentioned throughout this document. 
Rationale: The critical relative humidity is the relative humidity below which water will 
not form on a clean metal surface and electrochemical processes will not occur 
(ASM International 1987 [DIRS 133378], p. 82). For clean metal surfaces, the relative 
humidity must exceed about 60 percent before a thin film of moisture will form on the 
metal surface, providing an electrolyte for ionic current transfer (ASM International 1987 
[DIRS 133378], p. 82). Cleanliness, corrosion product build-up, and hygroscopic salts or 
contaminants can cause water absorption at lower relative humidities 
(ASM International 1987 [DIRS 133378], p. 80). On this basis, the existence of a 
threshold RH for initiation of corrosion processes is a reasonable assumption and consistent 
with data presented in corrosion handbooks. 
Confirmation Status: This is a reasonable assumption and does not require further 
confirmation. 
Use in Model: This assumption is used throughout this report. 
5.2 Assumption: The general corrosion rate of Alloy 22, at a given temperature, is assumed 
constant (i.e., time independent). 
Rationale: This assumption is considered conservative because the general corrosion rate 
of metals and alloys tend to decrease with time. This behavior is illustrated for Alloy 22 in 
Figure 7-1, which shows general corrosion rates of Alloy 22 at 90C for exposure times up 
to 5 years decrease with increasing exposure time. 
Confirmation Status: This is a conservative assumption because the general corrosion rate 
of metals and alloys tend to decrease with time; therefore, no additional confirmation of 
this assumption is necessary. 
Use in Model: This assumption is used throughout this report. 
5.3 Assumption: Localized corrosion can be either pitting corrosion on boldly exposed 
surfaces or crevice corrosion which takes place in occluded regions. In this report, the 
dominant form of localized corrosion is assumed to be crevice corrosion. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 5-2 October 2004 
Rationale: This is a conservative and bounding assumption because initiation thresholds 
for crevice corrosion, in terms of exposure parameters such as chemistry and temperature, 
are lower than those for pitting corrosion (Gdowski 1991 [DIRS 100859], Section 3.7; 
Agarwal 2000 [DIRS 163034], pp. 845 to 847). Additionally, crevice corrosion is applied 
to the entire waste package surface, though it is unlikely that crevice attack would occur 
over the entire surface area. 
Confirmation Status: This is a conservative and bounding assumption; therefore, no 
additional confirmation of this assumption is necessary. 
Use in Model: This assumption is used throughout this report. 
5.4 Assumption: When localized corrosion occurs, the localized corrosion of the WPOB is 
assumed to propagate at a (time-independent) constant rate. 
Rationale: This assumption is conservative because it is known that localized corrosion 
rates decrease with time (CRWMS M&O 1998 [DIRS 100349], Table 3-2; Hunkeler and 
Boehni 1983 [DIRS 162221]; McGuire et al. 1998 [DIRS 152193], Section 5.2.8, 
EPRI 2002 [DIRS 158069], Section 5.3.1; Frankel 1998 [DIRS 162216]; Newman and 
Franz 1984 [DIRS 162250]). 
Confirmation Status: This assumption is conservative because it is known that localized 
corrosion rates decrease with time; therefore, no additional confirmation of this assumption 
is necessary. 
Use in Model: This assumption is used throughout this report. 
5.5 Assumption: The localized corrosion data of the WPOB material (Alloy 22) that were 
generated in fully immersed conditions are assumed to be applicable to the localized 
corrosion processes of the waste package in contact with thin water films (under porous 
layers of dust and mineral precipitates) that have the same water chemistry as the fully 
immersed condition. 
Rationale: A thin water film condition in the presence of the porous layers is expected to 
form on the waste package surface in the nominal-case postclosure repository. The 
localized corrosion data of the WPOB material (Alloy 22) generated in fully immersed 
conditions are applicable to the thin film case, because a similar stagnant boundary layer is 
formed in the creviced region in both cases; therefore, it is reasonable to expect that the 
crevice corrosion behavior should be similar in both. Corrosion potentials measured in 
short-term experiments could be lower due to short-term decreases in the oxygen content 
near the sample surface that would be replenished at a faster rate under thin water film 
conditions than in fully immersed conditions. The corrosion potentials used in model 
development were obtained from long-term experiments in which the oxygen concentration 
would have reached steady state levels. 
Confirmation Status: This is a reasonable assumption and does not require further 
confirmation. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 5-3 October 2004 
Use in Model: This assumption is used throughout this report. 
5.6 Assumption: The corrosion behavior of the stress-mitigated (laser peened) outer lid 
closure weld region does not significantly differ from the corrosion behavior of a closure 
lid weld region that has not undergone stress-mitigation. 
Rationale: Laser peening involves the use of a laser pulse that induces a shock wave 
within the material being peened, resulting in the formation of a compressive surface layer. 
Laser peening causes less surface damage than conventional shot peening (Chen et al. 2002 
[DIRS 165441]) particularly because in laser peening no physical contact is made with the 
part to be peened. Comparisons of the corrosion rates (measured by the polarization 
resistance technique in simulated acidified water at 90C and potentiodynamic polarization 
curves) of unmitigated and laser-peened Alloy 22 samples have shown that laser peened 
samples exhibited lower corrosion rates than unmitigated samples (Chen et al. 2002 
[DIRS 165441], Figure 9). Also laser peened samples exhibited lower passive current 
densities (in potentiodynamic polarization tests) than unmitigated samples 
(Chen et al. 2002 [DIRS 165441], Figure 10). The potentiodynamic polarization curves did 
not show the initiation of localized corrosion before the transpassive potential was reached. 
Conservatively, no credit is taken in this report for the increased resistance to corrosion 
processes imparted by the laser peening process. 
Confirmation Status: This is a conservative assumption and does not require further 
confirmation. 
Use in Model: This assumption is used throughout this report. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 5-4 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-1 October 2004 
6. MODEL DISCUSSION 
6.1 ANALYSIS AND MODELING OBJECTIVES 
The purpose and scope of this report are to document the analyses and models for general and 
localized corrosion of the waste package outer barrier (WPOB). The purpose of the general 
corrosion model is to analyze degradation of the Alloy 22 outer barrier by general corrosion 
under the range of expected repository exposure conditions over the repository performance 
period. The purpose of the localized corrosion model is to analyze degradation of the Alloy 22 
outer barrier by crevice corrosion under the range of expected repository exposure conditions 
over the repository performance period. The general and localized corrosion models include 
several submodels, which account for dry oxidation, aqueous general corrosion, crevice 
corrosion initiation, crevice corrosion growth, microbially influenced corrosion (MIC), and 
effect of aging and phase instability. This report is used in downstream waste package 
degradation analyses. Treatment of seismic and igneous events and their consequences on waste 
package outer barrier performance are not discussed in this report, although the general and 
localized corrosion models developed in this report are suitable for use in these scenarios. 
6.2 FEATURES, EVENTS, AND PROCESSES RELEVANT TO THIS REPORT 
The development of a comprehensive list of features, events, and processes (FEPs) potentially 
relevant to postclosure performance of the Yucca Mountain repository is an iterative process 
based on site-specific information, design, and regulations. To support TSPA-LA, the FEP list 
was reevaluated in accordance with The Enhanced Plan for Features, Events, and Processes 
(FEPs) at Yucca Mountain (BSC 2002 [DIRS 158966], Section 3.2). Table 6-1 provides a list of 
FEPs included in this report and provides specific references to where the FEPs are discussed 
within this report. Table 6-2 provides a list of FEPs excluded in this report and provides specific 
references to sections within this report where the FEPs are discussed. DTN: 
MO0407SEPFEPLA.000 [DIRS 170760] also describes these FEPs and FEPs Screening of 
Processes and Issues in Drip Shield and Waste Package Degradation (BSC 2004 
[DIRS 169997]) for a complete list of all FEPs related to waste package and drip shield 
degradation. 
Table 6-1. Included FEPs in This Report 
FEP Number FEP Name Section(s) Where 
Described 
2.1.03.01.0A General corrosion of waste packages 6.4.3, 6.4.5 
2.1.03.03.0A Localized corrosion of waste packages 6.4.4 
2.1.03.05.0A Microbially influenced corrosion (MIC) of waste packages 6.4.5 
Table 6-2. Excluded FEPs in This Report 
FEP Number FEP Name Section(s) Where 
Described 
2.1.11.06.0A Thermal sensitization of waste packages 6.4.6 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-2 October 2004 
6.3 BASE-CASE CONCEPTUAL MODEL 
This section summarizes the expected exposure conditions and their relationship to the test 
solutions used. The base-case conceptual model that was developed for the analyses and models 
of the general corrosion and localized corrosion of the waste package outer barrier (WPOB) 
under the expected exposure conditions for the nominal-case postclosure repository is also 
described. ASTM C 1174-97 (1998 [DIRS 105725]) was followed for development of the 
models for general and localized corrosion of the WPOB documented in this report. 
Semiempirical modeling approaches were adopted by incorporating mechanistic understanding 
of the degradation processes into the modeling process. 
A schematic representation of the base-case conceptual model is shown in Figure 6-1. Additional 
details are described in the section in which the analyses and models are documented. 
Temperature, RH, pH, [Cl-], [NO3
-] 
RH = RHthreshold 
Dry Oxidation 
(not considered for 
WP degradation analysis) 
Ecorr = Ecritical 
General 
Corrosion 
General Corrosion 
and 
Localized Corrosion 
MIC 
if RH = 90% 
Yes No 
Yes 
No 
Water Chemistry 
Evolution Derived 
from Dust Leachate 
Water Chemistry 
Evolution Derived 
from Seepage 
Figure 6-1. Schematic Representation of the Base-Case Conceptual Model for the General and 
Localized Corrosion Model of the Waste Package Outer Barrier 
6.3.1 Expected In-Drift Temperature And Relative Humidity 
Figure 6-2 shows a summary of the range of waste package temperature and relative humidity 
histories for all waste packages (a and b), all CSNF waste packages (c and d) and all DHLW 
waste packages (e and f) (BSC 2004 [DIRS 169565], Figure 6.3-52) for the TSPA-LA base case. 
The ranges include the lower-bound, mean, and upper-bound infiltration flux cases and use of the 
mean thermal-conductivity values for all unsaturated zone layer units, including the host-rock 
units. The influence of the low-probability-seismic collapsed-drift scenario on in-drift 
thermohydrologic conditions is shown in Figure 6-3 (BSC 2004 [DIRS 169565], Figure 6.3-56). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-3 October 2004 
Source: BSC 2004 [DIRS 169565], Figure 6.3-52. 
NOTE: The ranges include the lower-bound, mean, and upper-bound infiltration flux cases and use of the mean 
thermal-conductivity values for all unsaturated zone layer units, including the host-rock units. 
Figure 6-2. Waste Package Temperature and Relative Humidity Ranges 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-4 October 2004 
Source: BSC 2004 [DIRS 169565], Figure 6.3-56. 
Figure 6-3. Thermohydrologic Variables for the Hottest Waste Package in the Low-Probability 
Seismic Collapsed Drift Scenario 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-5 October 2004 
The curves for waste package temperature are bounding representations for the drip shield 
because the waste package (and the waste it contains) is the heat source in the repository 
environment. The repository conditions can be divided into three temperature regimes. The 
relevant attributes of each regime are summarized as follows (BSC 2004 [DIRS 169565]): 
DryoutDrift walls will first be dried by ventilation air during the preclosure period. During 
postclosure, heat generated by radioactive decay increases the temperature of waste packages 
and drift walls above the boiling point of water. Because no significant seepage is expected when 
drift wall temperatures are above the boiling point of water, no aqueous phase corrosion due to 
seepage will exist. However, depending on the surface temperature and relative humidity 
conditions, the existence of liquid-phase water on the waste package or drip shield is possible 
due to the presence of dust or salt deposits. In the presence of such a deposit, a thin-film liquid 
phase can be established at a higher temperature and lower relative humidity than otherwise 
possible. Thus, formation of deliquescent brines in the absence of seepage may occur, and 
corrosion of the waste package and drip shield is considered in the context of these solutions. 
Calcium chloride-type brines are possible and predicted to occur in this regime, but they occur in 
the host rock when temperatures are above boiling and seepage into the drift is prevented by the 
vaporization barrier effect. 
TransitionSeepage into the drifts becomes possible as the waste package cools allowing the 
temperature of the drift wall to drop below the boiling point of water. If this occurs while the 
drip shield or waste package surface temperature, or both, is at or above the boiling point of the 
water, seepage waters will undergo evaporative concentration on the drip shield surface or the 
waste package surface at the time when the drip shield seepage diversion function is lost, thereby 
evolving into either carbonate- or sulfate-type brines. The drip shield, before it breaches, will 
mitigate seepage effects on the waste package. However, as in the dryout regime, formation of 
deliquescent brines could occur in this regime. 
Low TemperatureAs the waste package cools to a temperature below the boiling point of 
water, the in-drift relative humidity will increase, leading to less concentrated solutions 
contacting the waste package surfaces than at temperatures above the boiling point of water. 
With further cooling, the waste package surface temperature will drop and solutions contacting 
the waste package surface will be even less concentrated. Localized corrosion would not be 
expected under these conditions due to the low exposure temperatures and dilute solutions 
contacting the waste package surface. 
6.3.2 Relation of In-Drift Chemical Model Results to Corrosion Testing Environment 
The project has developed an understanding of the in-drift chemical environment for the three 
temperature regimes described in Section 6.3.1. The understanding is based on geochemical 
models and supporting data and analysis appropriate for the repository conditions. A description 
of the evolution of the chemical environment is provided in Engineered Barrier System: Physical 
and Chemical Environment (BSC 2004 [DIRS 169860], Section 6), which includes discussions 
of the relationship between the geochemical process model results, the range of expected in drift 
environments, and the chemical environments used in corrosion related testing. A brief summary 
of the chemical environment applicable to corrosion related testing follows. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-6 October 2004 
Brines that develop on the waste packages and drip shields are the result of either evaporative 
concentration of seepage water or deliquescence of deposited salts. Deposited salts are due to 
entrained matter in the ventilation air, dust and debris deposited within the drifts, or seepage 
waters evaporated to dryness. Seepage waters do not enter the drifts until host rock temperatures 
fall below 100C. Dust salts will deliquesce water from the atmosphere to form thin films on 
waste packages and drip shields above the normal boiling point of water (up to about 140C) 
(BSC 2004 [DIRS 169860], Section 6). 
Corrosion testing to determine the response of waste package, drip shield, and other in-drift 
materials is carried out in environmental conditions consistent with those predicted by in-drift 
chemical modeling. Corrosion testing environments were chosen based on the three types of 
natural brines: (1) calcium chloride, (2) carbonate, and (3) sulfate. Initial studies focused on the 
carbonate-type brine, based on reasoning that carbonate-type waters, typified by J-13 well water 
from the saturated zone near Yucca Mountain, are the expected types of waters at the repository 
(Harrar et al. 1990 [DIRS 100814]). 
The brine name reflects the chemical characteristic that distinguishes it from the other brines. 
Characterization of earth surface brines has guided, in part, the expected range of brine water 
chemistry in the repository. Some differences exist between brines formed at the earths surface 
and brines formed in the repository. These differences are mainly due to the chemistry of 
seepage waters and surface waters giving rise to brines, and differences between the salt 
chemistry of dust and the dissolved salt content of such surface waters. Two important general 
factors specific to the repository brines are the presence of nitrate and more-effective 
mechanisms for magnesium removal. Nitrate will be present in the deliquescent brines owing to 
multiple potential sources (BSC 2004 [DIRS 161237], Section 6.7.2.8) and the generally high 
solubility of nitrate minerals (BSC 2004 [DIRS 161237], Section 4.1.1.7). Magnesium will not 
be significant owing to a combination of low source (for the dust, as well as for at least some 
groundwaters) and multiple removal mechanisms (e.g., Mg sequestration in secondary silicates), 
most of which are enhanced by elevated temperature (BSC 2004 [DIRS 161237], 
Sections 6.7.2.10 and 6.7.2.11). 
Aqueous corrosion test solutions include several multiionic solutions based on a carbonate-based 
J-13 well water and test solutions containing the major species expected to affect corrosion such 
as nitrate ions. The standardized solutions developed as relevant test environments are presented 
in Table 6-3. These solutions include Simulated Dilute Water (SDW), Simulated Concentrated 
Water (SCW), Simulated Acidified Water (SAW), and Basic Saturated Water (BSW) aqueous 
test solutions. 
Table 6-3. Target Chemical Compositions of the Electrolyte Solutions (mg/L) Employed in the Long- 
Term Weight-Loss Measurements 
Concentration (mg/L) 
Ion Simulated Dilute 
Water (SDW) 
Simulated Concentrated 
Water (SCW) 
Simulated Acidified 
Water (SAW) 
Basic Saturated 
Water (BSW-SC) 
60C and 90C 60C and 90C 60C and 90C -- 
K 34 3,400 3,400 90,846 
Na 409 40,900 37,690 231,224.1 
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ANL-EBS-MD-000003 REV 02 6-7 October 2004 
Concentration (mg/L) 
Ion Simulated Dilute 
Water (SDW) 
Simulated Concentrated 
Water (SCW) 
Simulated Acidified 
Water (SAW) 
Basic Saturated 
Water (BSW-SC) 
Mg 1 <1 1,000 0 
Ca 0.5 <1 1,000 0 
F 14 1,400 0 1,616 
Cl 67 6,700 24,250 177,695.4 
NO3 64 6,400 23,000 177,167.9 
SO4 167 16,700 38,600 16,907.3 
HCO3 947 70,000 0 107,170.7 
Si 27 (60C) 
49 (90C) 
27 (60C) 
49 (90C) 
27 (60C) 
49 (90C) 7058.9 
Nominal pH 9.8 to 10.2 9.8 to 10.2 2.7 >12 
Source: DTN: LL040803112251.117 [DIRS 171362]. 
The following discussion on the relevance of the test media to the in-drift chemical environment 
is a summary of Engineered Barrier System: Physical and Chemical Environment Model 
(BSC 2004 [DIRS 169860], Section 6) and is used in this report as background information only. 
Calcium-Chloride Brines-The calcium-chloride brines have near neutral pH and no significant 
bicarbonate/carbonate, fluoride, or sulfate content. These brines also contain other cations such 
as sodium, potassium, and magnesium and other anions such as nitrate. The endpoint of the 
evaporative concentration of this type of brine contains Ca-Cl/NO3 or a mixture of 
Ca/Mg-Cl/NO3. The quantity of magnesium and calcium is limited due to the precipitation of 
calcium carbonates, sulfates, and magnesium silicates. Nitrate will be present; an endpoint brine 
of this type is dominated by calcium chloride and calcium nitrate. Formation of calcium-chloride 
brines is also limited in the repository. Brine generated by dust deliquescence is a potassium 
nitratesodium chloride brine with only a small probability of calcium due to the compositional 
nature of the dust leachate. Relative humidity dependence of the calcium-chloride brine 
composition is as follows. At low relative humidity, the aqueous solutions are dominated by 
calcium cations (very low sodium and potassium) and chloride and nitrate anions, because both 
calcium nitrate and calcium chloride are very soluble. At higher relative humidity, chloride and 
nitrate salts of sodium and potassium become soluble and dominate the aqueous solution 
compositions. This occurs at or above the deliquescence relative humidity for salts composed of 
these ions. 
Corrosion test solutions corresponding to the calcium chloride type of brine include calcium 
chloride, calcium chloride plus calcium nitrate, and sodium chloride aqueous solutions. The 
sodium chloride test solutions simulate the moderate relative humidity scenario where calcium is 
a minor component in the aqueous solution. 
Carbonate Brines-The carbonate brines are alkaline and do not contain significant calcium or 
magnesium content. In the early stages of the evaporative concentration, calcium precipitates 
predominately as carbonate mineral (calcite or aragonite) under equilibrium conditions. 
Magnesium precipitates as a minor component in the calcium carbonate species and as 
magnesium silicate. Potassium may be significant in some of these brines. Nitrate is expected to 
be an important component, and a brine of this type may evolve through a high extent of 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-8 October 2004 
evaporation into one in which nitrate is actually the dominant anion. The carbonate brine is likely 
to be represented as alkali metal (sodium, potassium) carbonate brine. Relative humidity 
dependence of carbonate brine composition is as follows. At low relative humidity, the aqueous 
solutions are dominated by nitrate and chloride anions with nitrate ions dominating at the lowest 
relative humidity. At moderate relative humidity (greater than 70-percent relative humidity), 
chloride ions dominate the solution composition. The nitrate-chloride solutions will have slightly 
elevated pH due to residual carbonate in solution. Significant amounts of carbonate and sulfate 
ion are not expected until the relative humidity is greater than 85 percent. 
Corrosion test solutions corresponding to the carbonate type of brine include the Simulated 
Dilute Water (SDW), Simulated Concentrated Water (SCW), Basic Saturated Water (BSW), and 
under certain circumstances, Simulated Acidified Water (SAW) aqueous test solutions (Table 
6-3). The BSW test solution is a highly concentrated alkaline solution with a boiling point of 
about 110C. The SCW test solution is a moderately concentrated alkaline solution and solutions 
in this concentration range form at relative humidity in the range of 90 to 95 percent. The SDW 
test solution is a dilute alkaline solution and solutions in this concentration range form at high 
relative humidity (greater than 99 percent). These may have characteristics of solutions at the 
drift wall, that is, typical of in-drift seepage waters. 
Under conditions of extreme evaporative concentration (i.e., low relative humidity), this type of 
brine containing high nitrate and chloride content would evolve into nitrate-chloride brine with 
low carbonate content. The SAW test solution has characteristics of low carbonate brine and of 
solutions in equilibrium with relative humidity of nominally 90 percent. The calcium and 
magnesium addition to this test solution makes it more able to sustain lower pH values due to the 
hydrolysis properties of these cations. 
Sulfate Brines-The sulfate brines have near-neutral pH and no significant bicarbonate/carbonate 
and calcium content. Calcium precipitates as carbonates and possibly as sulfates. In addition, 
they typically have only a small amount of magnesium, though some surface brines have been 
observed to have high magnesium (Drever 1997 [DIRS 140067], Table 15-1, Brines 1 to 3). The 
dominant cation is typically sodium. In the repository brines, potassium is comparable to sodium, 
and magnesium is insignificant. A brine of this type could evolve through a high extent of 
evaporation into one in which nitrate is the dominant anion. 
Relative humidity dependence of the sulfate brine composition is as follows. At low relative 
humidity, the aqueous solutions are dominated by nitrate and chloride anions with nitrate ions 
dominating at the lowest relative humidity. At moderate relative humidity (greater 
than 70 percent relative humidity), chloride ions dominate the solution composition. However, 
unlike the carbonate brines, these brines have near neutral to slightly acidic pH because of the 
lack of a carbonate component. Significant amounts of carbonate and sulfate ion do not exist 
until the relative humidity is greater than 85 percent because of the increase in solubility of 
sulfate minerals (sodium and potassium sulfates). Magnesium sulfate is present in insignificant 
quantities in these brines. 
The corrosion test solution corresponding to the sulfate type of brine is SAW (Table 6-3). This 
type of brine has near neutral to slightly acidic pH and, as noted, magnesium is not present in 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-9 October 2004 
seepage waters to any significant extent. The SAW test solution has characteristics of solutions 
in equilibrium with nominally 90 percent relative humidity. 
Two important general factors specific to the repository brines are the presence of nitrate and 
more-effective mechanisms for the removal of magnesium. Nitrate will be present in the 
deliquescent brines because of multiple potential sources (BSC 2004 [DIRS 161237], 
Section 6.7.2.8) and the generally high solubility of nitrate minerals (BSC 2004 [DIRS 161237], 
Section 4.1.1.7). 
Magnesium ions will not be significant because of a combination of low concentration (for the 
dust, as well as for at least some groundwaters) and multiple removal mechanisms (e.g., Mg 
sequestration in secondary silicates), most of which are enhanced by elevated temperature 
(BSC 2004 [DIRS 161237], Sections 6.7.2.10 and 6.7.2.11). 
Carbonate helps buffer the pH in any occluded geometry such as a crevice, and sulfate acts as a 
corrosion inhibitor. The compositions of these environments, as well as the BSW solution, are 
given in Table 6-3. Small amounts of carbonate form in the SAW and BSW solutions by 
interaction with gas phase carbon dioxide. The amount of carbonate formed was not determined 
experimentally because the small amounts will not affect the corrosion processes significantly. 
BSW has a boiling point near 110C. The total concentration of dissolved salts in the starting 
liquid was more concentrated than that in the standard SCW solution. After evaporation of 
approximately 90 percent of the water from the starting solution, the residual solution reaches a 
maximum chloride concentration and has a boiling point of approximately 110C, with a pH of 
about 11. The synthetic BSW solution composition can be slightly modified (mainly by adding 
sodium hydroxide) to cover a range of pH values, yielding solutions referred to as BSW-11, -12, 
and -13. 
Deliquescence of dust deposited on the waste packages and drip shield is another means by 
which brines can form on these engineered barrier system components. In the absence of salts, 
condensed water can be present on smooth surfaces only if the relative humidity is 100 percent. 
At lower relative humidity, most of the water evaporates, with residual water existing on the 
surface as a very thin adsorbate layer due to deliquescence. Dissolved salts lower the relative 
humidity at which such dryout occurs. Salt minerals in a dry system lower the relative humidity 
required for an aqueous solution to form. When the dissolved salt composition of a solution is 
known, the relative humidity at which dryout occurs at a given temperature can be determined. 
Conversely, the relative humidity for a given salt or set of salt minerals at which deliquescence 
occurs at a specified temperature can also be found. 
In all cases, the nitrate component, the most soluble species, dominates the solution composition 
at the deliquescent relative humidity or eutectic point of a mineral assemblage at elevated 
temperatures. At higher relative humidity, chloride minerals are soluble and could become a 
dominant ion. It is not until the relative humidity is much higher that the sulfate and carbonate 
compositions become appreciable. In essence, solutions are chloride and nitrate rich at low to 
moderate (less than 70 percent) relative humidity and, at higher relative humidity, sulfate and 
carbonate could be appreciable. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-10 October 2004 
6.3.3 Waste Package Outer Barrier Degradation Conceptual Model 
A schematic representation of the base-case conceptual model is shown in Figure 6-1. The 
design functions of the drip shield are to prevent the water seeping into the emplacement drifts 
from dripping directly onto the waste package and to provide protection from rockfall damage to 
the waste package. Before the drip shield breaches, the chemistry of liquid water contacting the 
waste package would be determined by the chemistry of leachate from dust that settles on the 
waste package surface. As the thermal heat output from the radioactive waste decays with time, 
thermal-hydrologic conditions in the emplacement drift dynamically change. Concentrated brines 
could form on the waste package surface from evaporative concentration of dust leachate. The 
chemical evolution of the brines would be dependent on the humidity and temperature 
conditions. When the drip shield breaches and, therefore, no longer performs its seepagediversion 
design function, the waste package underneath the breached drip shield could be 
directly contacted by seepage water. In this case, the water chemistry contacting the waste 
package would be determined primarily by the chemistry of the seepage water. In either case, 
hygroscopic salts may be deposited on the waste package surface due to evaporative 
concentration of the leachate from the dust and aerosols in contact with humid air, or, after drip 
shield breach, due to the evaporative concentration of the seepage water that contacts the waste 
package surface. Such hygroscopic salts enable aqueous solutions to exist as thin water films at 
relative humidity (RH) below 100 percent. The threshold RH (RHthreshold) at a given temperature, 
at which an aqueous solution can exist, is defined as the deliquescence point at that temperature. 
This threshold RH defines the lowest humidity condition necessary for aqueous electrochemical 
corrosion processes of a metal to occur at a given temperature. 
In postclosure repository environments, crevices could form between the waste package surfaces 
and the structural components, other materials in the emplacement drift, and mineral deposits 
from evaporative concentration of the solutions in contact with the waste package surface. The 
general corrosion and localized corrosion models of the WPOB in this report are based on data 
from crevice geometry samples. This treatment is conservative because creviced geometries will 
not be formed over the entire waste package surface. 
Dry oxidation of the WPOB occurs at any RH below the threshold RH (RHthreshold). This process 
results in the formation of an adherent, protective oxide film of uniform thickness. The rate of 
dry oxidation is generally limited by mass transport through the growing oxide film. As is 
discussed in Section 6.4.2, dry oxidation is not a performance limiting process of the WPOB 
under thermal conditions in the repository. Therefore, dry oxidation is not implemented in 
TSPA-LA. 
General corrosion (or passive corrosion) is the uniform thinning of the WPOB at its open-circuit 
corrosion potential (Ecorr). As stated in Assumption 5.1, general corrosion of the WPOB is 
assumed to occur at any RH above a threshold RH (RHthreshold). The general corrosion rate is 
temperature dependent. However, in this modeling work, the corrosion rate is assumed constant 
for a given temperature, (i.e., time independent). Therefore, at a given temperature, the depth of 
penetration or thinning of the WPOB due to general corrosion is equal to the general corrosion 
rate at that temperature multiplied by the time duration when the waste package surface is at that 
temperature. This assumption is considered conservative because the general corrosion rate of 
metals and alloys tends to decrease with time (Assumption 5.2 and Section 6.4.3.5). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-11 October 2004 
The general corrosion model developed in this report uses a general corrosion rate distribution 
determined from weight-loss measurements of Alloy 22 crevice specimens that were exposed for 
over 5 years in a wide range of multi-ionic solutions at the Long Term Corrosion Test Facility 
(LTCTF) (Section 6.4.3.2). As discussed in Section 6.4.3.2, the sample configuration (crevice, 
disk, or rod), metallurgical condition (mill annealed or as-welded), and water chemistry within 
the expected range do not have a significant effect on the general corrosion behavior of Alloy 22. 
Non-thermal stress mitigation processes, used to introduce a compressive stress layer in the outer 
lid closure weld region in order to delay the initiation of stress corrosion cracking, may introduce 
cold work into the material. Angeliu (2001 [DIRS 165442]) observed that unmitigated Stainless 
Steel Type 316NG weldments could contain up to 20 percent cold work due to weld shrinkage 
and differential thermal expansion. Therefore, the effects of cold work have been included in the 
analyses in this report. The temperature dependence of the general corrosion rate is represented 
with an Arrhenius relationship. The activation energy used in the Arrhenius relationship was 
determined from corrosion rates calculated from short-term polarization resistance measurements 
of Alloy 22 specimens with varying sample configurations and metallurgical conditions. The 
specimens were tested for a range of exposure conditions (temperature and water chemistry). As 
with the general corrosion rate from the long-term weight-loss measurements discussed above, 
the sample configuration (crevice, disk or rod), metallurgical conditions (mill annealed or aswelded), 
and water chemistry within the expected range do not have significant effect on 
temperature dependence of the general corrosion rate of the alloy (Section 6.4.3.4). The Electric 
Power Research Institute (EPRI 2002 [DIRS 158069], Section 5.3.2) presented a similar 
conceptual description by using literature data for similar corrosion-resistant Ni-Cr-Mo alloys. 
Localized corrosion is a corrosion in which the attack progresses at discrete sites or in a 
nonuniform manner. The rate of localized corrosion is generally much higher than the rate of 
general corrosion. As stated in Assumption 5.3, the current analysis assumes crevice corrosion is 
representative of localized corrosion of the WPOB under the exposure conditions expected in the 
postclosure repository. This is a conservative and bounding assumption because initiation 
thresholds for crevice corrosion of Alloy 22 in terms of water chemistry and temperature are 
lower than for pitting corrosion (Gdowski 1991 [DIRS 100859], Section 3.0; Haynes 
International 1997 [DIRS 100896]; Haynes International 1997 [DIRS 100897]). 
Localized corrosion of the WPOB is modeled with two model components: an initiation model 
and a propagation model. Localized corrosion of the WPOB occurs when the open-circuit 
corrosion potential (Ecorr) is equal to or greater than a critical potential (Ecritical), that is, .E 
(= Ecritical - Ecorr) = 0. This conceptual model of localized corrosion initiation is widely accepted 
by the corrosion community (Bhni 2000 [DIRS 164137], Section B; Dunn et al. 2000 
[DIRS 164495]; Dunn et al. 2003 [DIRS 164138]; Frankel 1998 [DIRS 162216]; Frankel 2002 
[DIRS 164140]; Frankel and Kelly 2002 [DIRS 164141]; and Beavers et al. 2002 
[DIRS 158781], Section 8.1). The crevice corrosion initiation model components (i.e., Ecorr and 
Ecritical) are represented as a function of temperature, pH, chloride ion concentration, and nitrate 
ion concentration. 
When it occurs, localized corrosion of the WPOB is assumed to propagate at a constant (timeindependent) 
rate (Assumption 5.4). This assumption is highly conservative because it is known 
that the localized corrosion rate decreases with time, and this is particularly more likely under 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-12 October 2004 
discontinuous and tortuous thin water films expected to form on the waste package surface in the 
postclosure repository. Section 6.4.4.8 provides a more detailed discussion. 
The WPOB is subject to microbially influenced corrosion (MIC) when the relative humidity at 
the WPOB surface is above 90 percent. The MIC initiation threshold RH is based on the 
analysis documented in Evaluation of the Impact of Microbial Activities on Drift Chemistry 
(BSC 2004 [DIRS 169991], Section 7.1). The effect of MIC on general corrosion of the WPOB 
is represented by a general corrosion enhancement factor. The enhancement factor was 
determined from the comparative analysis of the corrosion rates measured from the short-term 
polarization resistance measurements of Alloy 22 specimens tested in abiotic and biotic 
conditions. 
The waste package design and fabrication specification specifies that the WPOB base metal and 
all fabrication welds (except the closure lid welds) are fully annealed before the waste packages 
are loaded with waste (Plinski 2001 [DIRS 156800], Section 8.1). 
According to the analysis documented in Aging and Phase Stability of Waste Package Outer 
Barrier (BSC 2004 [DIRS 169983], Section 6.6.5), phase instabilities are not expected in 
Alloy 22 base-metal and welded material due to the thermal hydrologic exposure profiles in the 
repository. In addition, Project data (Section 6.4.6) show that the corrosion properties of aged 
welds are comparable to those of unaged welds. Phase instabilities are not expected to occur 
and, even if they do, they are not expected to have a significant effect on the corrosion 
properties; therefore, the effects of aging and phase instability of the WPOB are not modeled in 
TSPA-LA. 
Effects of oxidants, such as hydrogen peroxide generated from gamma radiolysis, on corrosion 
may be accounted for through the open-circuit corrosion potential (Ecorr). However, the 
radiolysis-enhanced corrosion has been screened out in FEPs Screening of Processes and Issues 
in Drip Shield and Waste Package Degradation (BSC 2004 [DIRS 169997], Section 6.2.32). 
Therefore, the radiolysis-enhanced corrosion of the WPOB is not considered in this waste 
package corrosion analysis. 
The waste package is a double-walled container with an outer barrier constructed of the highly 
corrosion-resistant Alloy 22 (UNS 06022) and an inner vessel made of Stainless Steel Type 316 
(UNS S31600). The inner vessel provides structural support to the thinner outer barrier 
(Plinski 2001 [DIRS 156800], Sections 1.0 and 4.0) while the outer barrier protects the inner 
vessel from significant corrosion degradation until failure of the outer barrier. Although the inner 
vessel could provide some delay of radionuclide release before it fails and could also retard the 
release rate of radionuclides from the waste package, no performance credit is taken for the 
corrosion resistance of the inner vessel (i.e., all corrosion performance is allocated to the 
WPOB). This model approach is used throughout the analysis and is conservative for the 
reasons noted above. 
After penetration of the WPOB, a crevice can form in the interfacial region between the Alloy 22 
outer cylinder and Stainless Steel Type 316 inner vessel. The formation of a low-pH crevice 
environment in this interfacial region is possible. A local acidic water chemistry could be 
developed through hydrolysis of dissolved metal ions in the crevice regions between the two 
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ANL-EBS-MD-000003 REV 02 6-13 October 2004 
barriers. Moreover, due to the limited availability of oxygen (dominant oxidizer for this 
condition) to such an occluded area, polarization of the creviced region due to differential 
aeration (between the creviced region and adjacent uncreviced region(s)) may occur. However, 
the analyses in this report show that Alloy 22 is highly resistant to crevice corrosion, especially 
in solutions with mixed ions. Alloy 22 will likely act as the cathode relative to the Stainless 
Steel Type 316 inner vessel under these exposure conditions. 
6.4 MODEL FORMULATION FOR BASE-CASE MODEL 
This section documents the analyses and models developed for general and localized corrosion 
of the WPOB under repository exposure conditions. The analyses and models also consider 
effects of microbiological processes (Section 6.4.5) and aging and phase instability 
(Section 6.4.6) of the WPOB for the repository conditions. 
6.4.1 Stability of the Passive Film in Repository Relevant Environments 
Corrosion performance of the WPOB depends on the integrity of the thin and adherent passive 
film formed on the alloy surface. The extremely low general corrosion rates and excellent 
resistance to localized corrosion of Alloy 22 in the repository intimately depend on the long-term 
stability of this passive film. This section discusses the conceptual understanding of passivity and 
passive film stability of Ni-Cr-Mo alloys by summarizing the data and information from the 
literature. Also discussed in this section is a summary of the experimental results of 
characterization for passive film on Alloy 22 tested in environments relevant to the conditions 
expected in the repository. 
6.4.1.1 Conceptual Description of Passivity and Passive Film Stability 
Passivity can be defined as the formation of a thin and adherent oxide or oxyhydroxide film that 
protects a metal or alloy from corrosive degradation. Corrosion performance of highly 
corrosion-resistant alloys such as Alloy 22 depends on the integrity of the passive film formed on 
the alloy surface in contact with the corrosive environment. Long-term stability of the passive 
film on the surface of the Alloy 22 waste package outer barrier is one of the key issues that 
determines the long-term performance of the waste packages in the repository. Extrapolation of 
the measured short-term corrosion rates over the regulatory period is based on the integrity of 
this passive film remaining stable over very long times. This section provides a brief description 
of the conceptual understanding of passivity and the passive film formation and stability on 
highly corrosion-resistant alloys such as Alloy 22. 
6.4.1.1.1 Passive Film Formed on Metals 
The passive film formed under aqueous condition is not a single layer, but rather has a stratified 
structure of at least two layers (Macdonald 1992 [DIRS 154720]; Macdonald 1999 
[DIRS 154721]; Marcus and Maurice 2000 [DIRS 154738], p. 138). According to this bilayer 
model, the passive film consists of an inner layer of oxide and an outer layer of hydroxide or 
oxyhydroxide. The inner oxide layer plays the role of a barrier layer against corrosion, and the 
outer layer plays the role of an exchange layer (Marcus and Maurice 2000 [DIRS 154738], 
p. 138) as discussed further in Section 6.4.1.1.2. In general, the chemical composition and 
thickness of passive films depend on the nature of the metal, the pH of the electrolyte in which 
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the metal is passivated, and the electrochemical potential (Macdonald 1992 [DIRS 154720]; 
Macdonald 1999 [DIRS 154721]; Marcus and Maurice 2000 [DIRS 154738], p. 138). For 
nickel, which can passivate in solutions over a wide range of pH, the passive film is generally 
composed of nickel (II) cations with an inner layer of NiO and an outer layer of Ni(OH)2 
(Marcus and Maurice 2000 [DIRS 154738], p. 140). 
Passive films formed on metal surfaces are generally not electronic conductors, but rather 
semiconductors or insulators. The electronic structures of passive films can be determined by 
photoelectrochemical measurements. However, structural analyses are rather difficult, due to the 
nanometer thickness of passive films and the roughness of the surfaces because of dissolution. 
The passive film formed on nickel (in 0.05 M H2SO4) displays crystallites, the sizes of which are 
reduced with increasing potential (Marcus and Maurice 2000 [DIRS 154738], p. 146). The 
shape of these crystallites also changes with potential (Marcus and Maurice 2000 
[DIRS 154738], Table 3-1). Another factor that must be considered is active dissolution, which 
occurs as long as the surface is not completely passivated. The dissolution rate increases with 
increasing potential. Dissolution processes may create new sites for oxide nucleation and can, 
thus, favor a higher density of oxide nuclei (Marcus and Maurice 2000 [DIRS 154738], p. 147). 
The passive film formed on nickel can be crystalline, with the surface exhibiting terraces and 
steps. The passive oxide film formed on chromium can have a nanocrystalline structure with 
oxide nanocrystals are cemented together by the chromium hydroxide outer layer, making the 
passive film extremely protective against corrosion-induced damage (Marcus and Maurice 2000 
[DIRS 154738], p. 149). 
6.4.1.1.2 Passive Film Growth Mechanisms 
As summarized in the literature (Macdonald 1992 [DIRS 154720]; Macdonald 1999 
[DIRS 154721]; Marcus and Maurice 2000 [DIRS 154738], Section 3.6), the barrier oxide layer 
(inner layer of the passive film) forms by generation of oxygen vacancies at the metalfilm 
interface, balanced in the steady state by dissolution of the barrier layer at the barrier layerouter 
layer interface. The outer layer forms via the hydrolysis and precipitation of cations transmitted 
through the barrier layer or by hydrolytic restructuring of the barrier layerouter layer interface. 
The distinctly different origins of the barrier and outer layers are amply demonstrated by the fact 
that both layers may incorporate alloying elements from the alloy substrate, but only the outer 
layer incorporates species from the solution. Furthermore, with respect to a fixed external frame 
of reference, the barrier layer grows into the substrate metal, whereas the outer layer grows 
outwards into the solution (Macdonald 1992 [DIRS 154720]; Macdonald 1999 [DIRS 154721]; 
Marcus and Maurice 2000 [DIRS 154738], Section 3.6). Thus, while the growth of the barrier 
layer is due to the generation of oxygen vacancies at the metalbarrier layer interface, the growth 
of the outer layer is commonly (but not exclusively) due to the transmission of cations through 
the barrier layer, either through cation vacancies or as cation interstitials, and their eventual 
emission at the barrier layerouter layer interface. The origin of the outer layer is not 
exclusively due to cation transmission, because it may also form via hydrolytic restructuring of 
the barrier layer at the barrier layerouter layer interface (Macdonald 1992 [DIRS 154720]; 
Macdonald 1999 [DIRS 154721]; Marcus and Maurice 2000 [DIRS 154738], Section 3.6). 
The electric current is carried by all charged species in the barrier layer, including cation 
vacancies, cation interstitials, and oxygen vacancies, which are generated and annihilated at the 
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interfaces and by dissolution of the barrier layer, depending on whether a change in oxidation 
state occurs (Macdonald 1992 [DIRS 154720]; Macdonald 1999 [DIRS 154721]). The principal 
mode of transport of defects is migration under the influence of a strong electric field, the 
magnitude of which is postulated to be established by the potential differences across the film 
and interfaces and by buffering due to Esaki (band-to-band) tunneling within the barrier layer 
(Macdonald 1992 [DIRS 154720]; Macdonald 1999 [DIRS 154721]). Because a barrier layer 
exists on all passive metals, all barrier layers are oxygen vacancy conductors to an extent that, in 
the steady state, is determined by the dissolution rate of the film. However, other defects may 
dominate the structural and electronic defect structures of the barrier layer. For example, the 
defect structure of the barrier layer on nickel is dominated by cation vacancies, while that on zinc 
is dominated by cation interstitials, although oxygen vacancies exist in both cases. 
6.4.1.1.3 Surface-Enrichment of Chromium on Passivated Nickel-Base Alloys 
Chromium concentration plays a significant role in the passivation of austenitic nickel-base 
alloys, such as Alloy 22. The passive film on Alloy 22 can be described by the bilayer model 
(Macdonald 1992 [DIRS 154720]; Macdonald 1999 [DIRS 154721]; Marcus and Maurice 2000 
[DIRS 154738], Section 3.6). The concentration of Cr+3 in the inner oxide layer is higher than 
the nominal chromium content of the alloy (Marcus and Maurice 2000 [DIRS 154738], p. 153; 
Lorang et al. 1990 [DIRS 154718], Figures 1 and 2). The mechanism of surface enrichment of 
chromium in the barrier layer has been developed within the framework of the point defect 
model (PDM) (Zhang and Macdonald 1998 [DIRS 154743]; 1998 [DIRS 154742]). The PDM is 
based on the selective oxidation of the elements at the alloybarrier layer interface, differences in 
transport properties of the species in the barrier layer, and selective oxidation of the elements at 
the barrier layerouter layer interface. In the specific case of the passive film on iron-chromium 
alloys, the enrichment of chromium in the barrier layer appears to entail the dissolution of iron 
and the oxidative segregation of chromium (Marcus and Maurice 2000 [DIRS 154738], p. 153). 
Iron atoms are detached from the surface and dissolve into solution as ions, whereas chromium 
atoms are rapidly oxidized. The passive film forms by the nucleation and growth of a Cr2O3-like 
phase (Marcus and Maurice 2000 [DIRS 154738], p. 153). However, the barrier layers on 
iron-chromium and nickel-chromium alloys are not pure chromium oxide (Cr2O3), but contain 
significant amounts of other metal species, such as nickel, ferrous, and ferric ions (Lorang et al. 
1990 [DIRS 154718]). Finally, it is important to note that the accurate description of alloy 
segregation phenomena requires solving the moving boundary problem, because the interfaces 
at which the segregation reactions occur and the phases bounded by these interfaces move 
differently with respect to a fixed external frame of reference. This is the approach adopted in 
the PDM (Zhang and Macdonald 1998 [DIRS 154743]; Zhang and Macdonald 1998 
[DIRS 154742]). 
6.4.1.1.4 Role of Molybdenum 
There is a consensus that molybdenum reduces the rate of anodic dissolution in the active state 
(Marcus and Maurice 2000 [DIRS 154738], pp. 155 to 158). However, the mechanism by which 
molybdenum additions benefit the corrosion resistance of nickel-chromium-molybdenum alloys 
is not fully understood. Molybdenum tends to be located preferentially at local defects on the 
surface, which normally act as dissolution sites. The slowing down of the dissolution rate could 
be due to the strengthened metal-metal bonds when molybdenum is present (Marcus and 
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Maurice 2000 [DIRS 154738], pp. 155 to 158). Further, the presence of molybdenum 
counteracts the deleterious effect of certain species such as sulfur, which can cause grainboundary 
attack in that it bonds to sulfur and then dissolves mitigating the detrimental effects of 
sulfur (Marcus and Maurice 2000 [DIRS 154738], p. 158). 
An analytical prediction of the role played by molybdenum (or any alloying element) in 
inhibiting passivity breakdown on alloys is provided by the point defect model (PDM) (Urquidi 
and Macdonald 1985 [DIRS 154741]). The PDM accounts quantitatively (within the accuracy of 
the experimental data) for the impact of molybdenum on the pitting resistance of 18 Cr-8 Ni 
stainless steels (e.g., Stainless Steel Type 316, which contains molybdenum versus Stainless 
Steel Type 304, which contains no molybdenum). In this case, the highly oxidized molybdenum 
ions present substitutionally in the barrier layer lattice form immobile, positively charged 
centers. For example, recognizing that the barrier layer on chromium-containing stainless steels 
and nickel-base alloys is essentially Cr2O3, substitution of Mo6+ into a chromium cation vacancy 
would produce the immobile species (  3
Cr Mo ). These immobile species can interact 
electrostatically with the mobile, negatively charged cation vacancies ( 3' 
Cr V ), the condensation of 
which at the metalfilm interface under breakdown conditions is responsible for passivity 
breakdown (Macdonald 1992 [DIRS 154720]; Macdonald 1999 [DIRS 154721]). Thus, the 
solute-vacancy interaction reduces the free cation vacancy concentration and diffusivity, which 
results in a positive shift in the breakdown voltage and a lengthening of the induction time 
(i.e., the alloy becomes more resistant to passivity breakdown). The electrostatic interaction is 
described rigorously in terms of ion-pairing theory that is commonly employed to describe ionic 
interaction in solutions. This solute-vacancy interaction model (Urquidi and Macdonald 1985 
[DIRS 154741]) successfully accounts for the positive shift in the breakdown voltage upon 
adding molybdenum to the alloy without the need for arbitrary, adjustable parameters. Most 
importantly, the solute-vacancy interaction model accounts for why molybdenum must be 
present in the barrier layer at concentrations greater than about 2 percent for significant 
protection to be achieved. 
Finally, complexing between  3
Cr Mo and a defect will only occur if the defect is negatively 
charged (i.e., if the defect is a cation vacancy) (Urquidi and Macdonald 1985 [DIRS 154741]). 
However, the Cr2O3 passive film on chromium containing alloys is normally n-type in electronic 
character because the dominant defect in the film is either a cation interstitial or an oxygen 
vacancy, both of which are formally positively charged (Urquidi and Macdonald 1985 
[DIRS 154741]). Consequently, there should be little solute (  3
Cr Mo )  vacancy (   
O V or + . 
i M ) 
interaction and pairing, and molybdenum should have little consistent impact on the passive 
current density. 
6.4.1.2 Characterization of Alloy 22 Passive Film 
The passive film on Alloy 22 has been studied at 95C in a high pH salt environment 
characteristic of concentrated Yucca Mountain groundwater (Andresen et al. 2003 
[DIRS 170360], Section 3). Measurements of corrosion potential (CP) versus time, potentiostatic 
polarization (PSP) and cyclic potentiodynamic polarization (CPP) behavior were conducted to 
evaluate the passivity of these alloys. The passive films were also analyzed by x-ray 
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photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) to obtain the 
chemical composition and cross-sectional view of the metal, oxide layers and interfaces. 
6.4.1.2.1 Summary of Experimental Procedures 
All materials were tested in the as-received condition. Specimens (3 mm in diameter by 60 mm 
in length cylinders for CP, PSP, and CPP measurements, and 10 mm  10 mm  0.8 mm 
coupons for oxide analysis) were cut by electrodischarge machining and then wet-ground using a 
600-grit SiC paper before testing. Specimens for electrochemical measurements were spot 
welded to a polytetrafluoroethylene insulated Alloy 600 wire and mounted in an insulated fitting. 
The testing solution used was diluted (by a factor of about 18) Basic Saturated Water (BSW) 
(Table 6-3) with a pH of approximately 12.4 at 95C. 
The chemicals were mixed with water that had been heated to the boiling point in an autoclave. 
All testing was performed in either a Hastelloy C-276 autoclave body or a commercial-purity 
titanium autoclave. Stainless steel components were present in all the autoclaves used. No signs 
of corrosion were observed on these stainless steel components, suggesting that the testing 
solution was not extremely aggressive. Solution was sampled from the autoclaves during the 
test. 
To prevent evaporative loss of water, a four-foot-long tube-in-tube heat exchanger was used, 
with cooling water on the outside. The solution level in the test autoclave was monitored 
periodically by checking for continuity between the autoclave and an insulated stainless steel 
feed-through bar. No water addition was needed. 
All potentials were measured with respect to a saturated calomel electrode (SCE) reference 
electrode. A Luggin probe with a porous zirconia membrane filled with the test solution was 
used to maintain the reference electrode at room temperature. A flag-shaped platinum sheet was 
employed as a counter electrode. All tests were performed at 95C  1C. CPP scans 
at 0.17 mV/sec were started at 50 mV below the corrosion potential (obtained 1 hour after 
immersion in solution), then continued toward the more noble potential direction. The scans 
were reversed when a current density of 5 mA/cm2 was reached. After the completion of each 
test, specimens were cleaned ultrasonically in deionized water, dried, and the specimen surface 
was examined with a scanning electron microscope (SEM). In addition, potentiostatic 
polarization (PSP) tests were conducted by applying various anodic potentials for 24 hours to 
measure the passive current and to characterize the oxide properties. The oxide composition and 
thickness were analyzed by XPS. The XPS data are quantitative for film composition, but the 
thickness of the oxide film is considered qualitative because precise calibrations of sputtering 
rate on an oxide of this composition was not performed (although very good estimates exist). No 
visual evidence of localized corrosion attack was observed after CPP or PSP measurements. 
The cross-sectional TEM sample was prepared using a focused ion beam system. The bulk 
sample was placed into the focused ion beam system, and the region of interest was coated with a 
1-m-thick platinum layer using the in-situ metal deposition facilities of the focused ion beam 
system. The platinum layer was used to protect the underlying material. Staircase-shaped cuts 
were milled on either side of the region of interest using a gallium ion source. The ion current 
was reduced as the thickness of the section approached the desired dimension. The dimension of 
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the final TEM cross section was 10-m long, 4-m deep and 150-nm thick. The sample was 
then removed from the focused ion beam chamber, and the TEM cross-section was removed 
from the bulk sample and placed on a porous carbon grid using a micromanipulator. 
6.4.1.2.2 Characterization of Passive Films Formed Under Potentiostatic Polarization 
The passive current transition behavior and oxide thickness formed on Alloy 22 at various anodic 
potentials is shown in Figure 6-4. The passive current density increases with the applied 
potential, and the oxide film becomes slightly thicker. Figure 6-5 shows the elemental 
distribution on the outermost oxide layer (not the very thin protective inner barrier layer 
responsible for passive behavior) formed on Alloy 22 at various anodic potentials. Applied 
anodic potentials in Figure 6-4 and Figure 6-5 were chosen from CPP curves 
(Andresen et al. 2003 [DIRS 170360], Figure 3-4). Steady-state currents were normally 
achieved within a 5 to 10 hour period of polarization at applied potentials. In addition to anodic 
dissolution, there may be contributions to the measured current due to redox reactions occurring 
in the mixed-salt environment. No evidence of localized corrosion attack was observed on test 
specimens after polarization. 
0
1
2
3
4
5
6
7
8
9 
10
-500 -400 -300 -200 -100 0 100 200 300 
APPLIED POTENTIAL, mV(SCE) 
CURRENT DENSITY, A/cm2: OXIDE THICKNESS, nm
Alloy 22 
Dilute Y-M mixed salt solution, 95oC 
Oxide Thickness 
Current Density 
Source: Andresen et al. 2003 [DIRS 170360], Figure 3-8. 
Figure 6-4. Passive Current Densities and Oxide Thickness as a Function of Applied Potential for 
Alloy 22 
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0.1
1 
10 
100
-500 -400 -300 -200 -100 0 100 200 300 
APPLIED POTENTIAL, mV(SCE) 
OUTMOST SURFACE CONCENTRAITON, atomic % 
O
W
Mo 
Ni 
Cr 
Si 
Source: Andresen et al. 2003 [DIRS 170360], Figure 3-9. 
Figure 6-5. Elemental Concentration on the Outermost Oxide Layer as a Function of Applied Potential 
for Alloy 22 
Note that the current density increased after the applied anodic potential was increased to 
200 mV(SCE) and a slight increase in oxide thickness was also observed. However, no evidence 
was observed to conclude the current increase and slightly thicker oxide at high anodic potentials 
were due to localized passive film breakdown. The primary cause of the high current density is 
due to changes in surface chemistry and oxidation states of molybdenum and tungsten (to 
MoO4
2- and WO4
2-) in the passive film (Pourbaix 1974 [DIRS 100817], Sections 10.2 and 10.3). 
6.4.1.2.3 Oxide Film Analysis 
The chemical composition and structure of the oxide film plays very important role in the 
corrosion protection process. The mechanism and kinetics of corrosion processes can be altered 
by the chemical and physical properties of oxide films. Figure 6-6 shows the TEM cross-section 
micrograph of the oxide film formed on Alloy 22 after two-month immersion at open-circuit 
potential in mixed-salt solution at 95C. An oxide approximately 5 to 8 nm thick, enriched with 
chromium, was formed. Electron diffraction patterns showed a thermodynamically stable 
Cr2O3-rich oxide film containing NiO. These results are consistent with the results of Lloyd et 
al. (2003 [DIRS 167921], Table II). 
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Alloy 22: After 2 Months in Dilute Y-M Groundwater 
Pt Coating Layer 
Cr Oxide 
(HighCr& O Signal) 
Matrix 
Source: Andresen et al. 2003 [DIRS 170360], Figure 3-10. 
Figure 6-6. TEM Micrograph Showing the Cross-Sectional Views and Oxide Chemistry Formed on 
Alloy 22 After 2-Month Immersion in a Mixed-Salt Environment at 95C 
XPS analysis was performed to get quantitative chemical composition profile regarding the oxide 
thickness and elemental distribution through the oxide film. Figure 6-7 shows the elemental 
concentrations of the outermost oxide layer formed on Alloy 22 in a mixed-salt solution at 95C 
as a function of immersion time. The oxide film on Alloy 22 was enriched with chromium and 
nickel, and no significant amounts of molybdenum and tungsten were measured. This is 
consistent with the findings by other investigators (Lorang et al. 1990 [DIRS 154718]; 
Macdonald 1999 [DIRS 154721]; Marcus and Maurice 2000 [DIRS 154738], p. 153). Figure 6-7 
shows that after two months the elemental concentrations change little with increasing exposure 
time. A large amount of SiO2 (see the silicon curve in Figure 6-7) and small amounts of other 
salts on the outer oxide film were detected, but no evidence of penetration of SiO2 to the 
underlying substrate was observed. If these elements were adjusted for (e.g., removed from 
consideration) in the atomic percent calculations, the amounts of the primary alloy elements 
(e.g., nickel, chromium, molybdenum, and tungsten) would be higher than shown in Figure 6-7. 
Figure 6-8 shows the oxide thickness formed on Alloy 22 as a function of immersion time. After 
two months, the oxide film thickness on Alloy 22 is approximately 7-nm thick and, after eight 
months, the oxide film is about 13-nm thick. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-21 October 2004 
Source: Andresen et al. 2003 [DIRS 170360], Figure 3-11. 
Figure 6-7. Elemental Concentration on the Outermost Oxide Layer Formed on Alloy 22 in a Mixed-Salt 
Environment at 95C as a Function of Immersion Time 
0 
20 
40 
60 
80 
100 
120 
140 
160 
180 
200
0 1 2 3 4 5 6 7 8 9 
IMMERSION TIME, month 
OXIDE THICKNESS,  
Oxide formed on Alloy 22 and Ti-Grade 7 in dilute Y-M solution at 95oC 
Ti-Grade 7 
Alloy 22 
Source: Andresen et al. 2003 [DIRS 170360], Figure 3-13. 
Figure 6-8. Oxide Thickness Formed on Alloy 22 and Ti Grade 7 as a Function of Immersion Time at 
95C in a Mixed-Salt Environment 
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ANL-EBS-MD-000003 REV 02 6-22 October 2004 
6.4.1.3 Summary 
The conceptual understanding of the growth and stability of the passive film on Alloy 22 is 
described based on summarized data and information from the literature. The passivity of 
Alloy 22 is examined by measuring the corrosion potential and polarization behavior in a mixedsalt 
environment at 95C with a pH of about 12.4. Steady-state corrosion potentials of Alloy 22 
are measured. The surface analysis data indicated that the oxide layers responsible for passivity 
of Alloy 22 consist of chromium oxide (Cr2O3) containing NiO. After eight months of exposure 
to the mixed-salt solution at 95C with a pH of about 12.4, 12 to 13 nm thick oxide films were 
formed on Alloy 22 specimen surfaces. In addition, the passive films formed on Alloy 22 at high 
anodic potentials (> 0 mV versus SCE) contained more molybdenum and tungsten than the ones 
formed at lower anodic potentials (< 0 mV versus SCE). No evidence of localized corrosion 
attack on Alloy 22 after potentiostatic polarization measurements was observed. No significant 
change in the open-circuit potential (OCP, or corrosion potential) of the test electrodes was 
observed. These data indicate that with increased time (1) the passive films become very 
protective and stable, (2) contributions from metal corrosion become extremely small, and 
(3) redox reactions from the species in solution are stable. Overall, the passive films formed on 
Alloy 22 can be concluded to be very stable over long time periods. 
6.4.2 Dry Oxidation 
Dry oxidation of Alloy 22 occurs at any RH < RHthreshold, thereby forming an adherent, protective 
oxide film of uniform thickness. The dry oxidation model presented here considers uniform 
oxidation of the WPOB surface. The protective oxide film is primarily Cr2O3, as discussed in the 
previous section. The oxidation reaction for the formation of this oxide is (Welsch et al. 1996 
[DIRS 114895]): 
3 2 2 3 2 3 4 O Cr O Cr .. . + (Eq. 6-1) 
The rate of dry oxidation is considered to be limited by mass transport through this growing 
metal oxide film. Ficks first law (Jones 1992 [DIRS 169906], Section 12.3.1) is applied, 
considering a linear concentration gradient across the oxide film of thickness x: 
x
C D 
x
C D J oxde oxide oxide 
. -  
. 
. - = (Eq. 6-2) 
where Joxide is the molar flux of the reacting species in the oxide, Doxide is the diffusivity of the 
reacting species in the oxide, .C is the corresponding differential molar concentration. One can 
describe the oxide growth with a parabolic rate law as (Jones 1992 [DIRS 169906], 
Section 12.3.1): 
x 
k 
dt 
dx p = (Eq. 6-3) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-23 October 2004 
where x is the oxide thickness and kpx is the thickness-based parabolic rate constant and t is the 
time. Integration of Equation 6-3 leads to: 
t k x x p  + = 2
0 (Eq. 6-4) 
where x0 is the initial oxide thickness, x is the oxide thickness at time t, and k is a temperaturedependent 
parabolic rate constant. Dry oxidation of metal is a thermally activated process. 
Therefore, the rate constant, kp obeys the Arrhenius equation (Jones 1992 [DIRS 169906], 
Section 12.3.1): 
RT E 
p p 
a e k k / 
0 
- = 
(Eq. 6-5) 
where kp0 is a constant, Ea is the activation energy, and R is the universal gas constant 
(8.314 J/mol K) (Lide 1991 [DIRS 131202], inside rear cover). 
To facilitate an approximate calculation, published values of k can be used (Welsch et al. 1996 
[DIRS 114895]). The data in Figure 18 of this reference were fit to an Arrhenius relation such 
that all observed values of k fall below a line defined by: 
.. 
. 
.. 
. - - = .. 
. 
.. 
. 
. .. 
. 
. .. 
. 
T 
m k 12500 5 . 3 
sec 
log 
2 
(Eq. 6-6) 
where T is defined as the absolute temperature in Kelvin. Recent measurements of the thickness 
of the Alloy 22 oxide film exposed to air at 550C showed that the oxide film approaches a 
limiting thickness of about 0.025 to 0.050 m (25 to 50 nm) after about 333 days of exposure 
(DTN: LL030406412251.045 [DIRS 163469]). If this oxide film thickness is considered the 
depth of metal penetration (this is very conservative as the oxidemetal volume (Pilling- 
Bedworth) ratio for chromia is about 2.02 (ASM International 1987 [DIRS 133378], p. 64)), then 
a penetration rate of 0.027 to 0.054 m/yr (27 to 54 nm/yr) is obtained. For that temperature, the 
value of k corresponding to the upper limit from Equation 6-6 is 2.06  10-19 m2/sec 
(6.51 m2/yr). Ignoring the initial oxide thickness in Equation 6-4, after one year, this 
corresponds to a growth of 2.55 m (about 2.55 m/yr). This shows that the model estimates are 
about 100 times greater than the measured thickness, and the above expression represents a very 
conservative upper bound. 
Logarithmic growth laws may be more appropriate at lower temperatures than parabolic laws. 
However, the logarithmic law predicts that the oxide thickness (penetration) asymptotically 
approaches a small maximum value. In contrast, the parabolic law predicts continuous growth of 
the oxide, which is more conservative. As conservative estimates of the rate of dry oxidation 
based on parabolic growth kinetics are not life limiting and reliable data for determining the 
maximum oxide thickness for Alloy 22 are not available, the parabolic growth law was used for 
the WPOB. 
For a temperature of 350C, the value of k from Equation 6-6 is 2.73  10-24 m2/sec 
(8.61  10-5 m2/yr). After one year, this corresponds to a growth of 0.0093 m 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-24 October 2004 
(about 9.3 nm/yr). As discussed in Section 6.4.3, this estimated dry-oxidation rate is comparable 
to the mean value of the general corrosion rate of Alloy 22 at lower temperatures. Assuming a 
constant oxide penetration rate of 0.0093 m/yr (i.e., exposure to a constant temperature of 
350C), the total penetration depth in the WPOB by dry oxidation in 10,000 years after 
permanent closure is only 93 m, which is negligibly small (less than 1 percent of the total 
thickness of the WPOB (20 mm)). 
On the basis of the above analysis, dry oxidation is not expected to be a performance limiting 
process of the WPOB under the exposure condition expected in the repository. Therefore, dry 
oxidation is not included in the waste package performance analysis. 
6.4.3 General Corrosion 
General corrosion (or passive corrosion) is the uniform thinning of the WPOB at its open-circuit 
corrosion potential (Ecorr). General corrosion can occur under immersed conditions or when a 
liquid film exists on the surface. At a given surface temperature, the existence of liquid water on 
the waste package surface depends upon the hygroscopic nature of salts, minerals, or both 
deposited on the surface. In the presence of such a deposit, a liquid-phase can be established at a 
higher temperature and lower RH than otherwise is possible. General corrosion of the WPOB 
occurs at any RH above a threshold RH (RHthreshold) (Assumption 5.1). The general corrosion 
rate is temperature dependent. For a given temperature, the general corrosion rate is assumed 
constant (i.e., time-independent) (Assumption 5.2). Therefore, for a given temperature, the depth 
of penetration or thinning of the WPOB by general corrosion is equal to the general corrosion 
rate at that temperature, multiplied by the time duration that the waste package surface is at that 
temperature. This assumption is considered conservative because the general corrosion rate of 
metals and alloys is known to decrease with time (Section 6.4.3.5). 
As is discussed in the following sections, general corrosion rates of the WPOB have been 
estimated from the weight-loss data of Alloy 22 samples after 5-year exposure in the Long Term 
Corrosion Test Facility (LTCTF) (Estill 1998 [DIRS 117697], Section 2.2). The LTCTF 
provides a comprehensive source of corrosion data for Alloy 22 in environments relevant to the 
repository. The LTCTF facility is described in detail in a previous publication by Estill (1998 
[DIRS 117697], Section 2.2) and relevant experimental details are summarized in the next 
section. The 5-year weight-loss measurement data is documented in 
DTN: LL030412512251.057 [DIRS 163712]. 
6.4.3.1 Long-Term Weight-Loss Measurements 
6.4.3.1.1 Test Temperatures and Aeration 
The LTCTF is equipped with several nonmetallic tanks. Each tank has a total volume of 
approximately 2,000 L and is filled with approximately 1,000 L of aqueous test solution. The 
temperature of the solution in a particular tank is controlled at either 60C or 90C. The test 
solution in each tank is covered with a blanket of air flowing at approximately 150 cm3/min, and 
agitated. The reported test temperature corresponded to the liquid phase temperature. Details of 
the facility are described by Estill (1998 [DIRS 117697], Section 2.2). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-25 October 2004 
6.4.3.1.2 Test Specimens 
Samples used for determination of weight-loss during long-term were mounted on insulating 
racks and placed in the tanks. Approximately half of the samples were submersed, half were in 
the saturated vapor above the aqueous phase, and a limited number were at the water line. 
Condensed water was present on specimens located in the saturated vapor. 
Two coupon types were used for weight-loss measurements. These are identified as weight-loss 
coupons and crevice coupons. The nominal dimensions were 2 in.  1 in.  . in. (approximately 
50 mm  25 mm  3 mm) and 2 in.  2 in.  . in. (50 mm  50 mm  3 mm), respectively. The 
coupons had a 0.312-in. (7.9-mm) diameter hole in the center for sample mounting. For both 
coupon types (weight-loss and crevice), two metallurgical conditions were used (i.e., wrought 
material (only base metal) and welded material). The coupons were fabricated from Alloy 22 
plate stock. All weight-loss coupons were affixed using an insulating -in. (12.7-mm) diameter 
polytetrafluoroethylene or ceramic washer, while all crevice coupons were affixed using a -in. 
(19.1-mm) diameter polytetrafluoroethylene or ceramic crevice former. The purpose of the 
crevice former was to create an environment that might induce corrosion at the contact interface, 
or under occluded conditions. Further details of the sample configuration are provided elsewhere 
(Estill 1998 [DIRS 117697], Section 2.2.5; DTN: LL030412512251.057 [DIRS 163712]). 
6.4.3.1.3 Test Media 
The weight-loss measurement testing includes a wide range of plausible generic test media, 
including Simulated Dilute Water (SDW), Simulated Concentrated Water (SCW), and Simulated 
Acidified Water (SAW). The compositions of three of these solutions are summarized in Table 
6-3. Basic Saturated Water (BSW) is not used for long-term weight-loss testing (as no BSWcontaining 
tanks were installed) but is used in other testing activities discussed in this report; 
therefore, its composition is included in Table 6-3. The SCW test medium is three orders-ofmagnitude 
(1,000) more concentrated than J-13 well water and is slightly alkaline 
(pH approximately 10). The SAW test medium is three orders-of-magnitude (1,000) more 
concentrated than J-13 well water and is acidic (pH approximately 2.7). Concentrated solutions 
are intended to mimic the evaporative concentration of the electrolytes on the hot waste package 
surface (Estill 1998 [DIRS 117697], Section 2.2). 
6.4.3.1.4 Test Matrix 
The welded and nonwelded (wrought) coupons were tested under 12 different conditions (three 
electrolytes  two temperatures  two exposure conditions). The exposure time for each 
specimen was approximately 5 years. The specimen label and vessel numbers are shown in 
Table 6-4. Each sample was designated with three letters and three characteristic numbers. The 
letter D represents Alloy 22, the letter C indicates a crevice coupon, the letter W indicates a 
weight-loss coupon, the letter A indicates that the coupon does not contain a weld seam, and 
the letter B indicates that the coupon contains a weld seam along the middle of the specimen. 
Table 6-4 shows that a total of 134 test specimens were examined. Twelve welded crevice 
samples, representing each of the different test conditions, were used for surface analyses 
(designated (SA) in Table 6-4) and the remaining 122 samples were used for weight-loss 
determination. The weight-loss samples tested at the water line were included in the model 
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ANL-EBS-MD-000003 REV 02 6-26 October 2004 
analysis because there were no noticeable differences in the measured weight losses between the 
water line and liquid phase samples for the same exposure conditions (i.e., water chemistry and 
temperature). 
Table 6-4. List of Examined Weight-Loss and Crevice Alloy 22 Coupons 
SAW 
60C 
SAW 
90C 
SCW 
60C 
SCW 
90C 
SDW 
60C 
SDW 
90C 
Sample - 
Exposure Vessel 25 Vessel 26 Vessel 27 Vessel 28 Vessel 29 Vessel 30 
Weight-Loss - 
Vapor Phase 
DWA019 
DWA020 
DWA021 
DWA059 
DWA060 
DWA061 
DWA089 
DWA090 
DWA091 
DWA129 
DWA130 
DWA131 
DWA147 DWA174 
Crevice  
Vapor Phase 
DCA019 
DCA020 
DCA021 
DCA049 
DCA050 
DCA051 
DCA079 
DCA080 
DCA081 
DCA109 
DCA110 
DCA111 
DCA139 
DCA140 
DCA141 
DCA175 
DCA176 
DCA177 
Weight-Loss - 
Liquid Phase 
DWA022 
DWA023 
DWA024 
DWA062 
DWA063 
DWA064 
DWA092 
DWA093 
DWA094 
DWA132 
DWA133 
DWA134 
DWA148 DWA175 
Crevice  
Liquid Phase 
DCA022 
DCA023 
DCA024 
DCA052 
DCA053 
DCA054 
DCA082 
DCA083 
DCA084 
DCA112 
DCA113 
DCA114 
DCA142 
DCA143 
DCA144 
DCA178 
DCA179 
DCA180 
Weight-Loss - 
Waterline DWA034 DWA039 DWA104 DWA109 DWA154 DWA167 
Welded 
Weight-Loss - 
Vapor Phase 
DWB019 
DWB020 
DWB021 
DWB059 
DWB060 
DWB061 
DWB089 
DWB090 
DWB091 
DWB129 
DWB130 
DWB131 
DWB147 DWB174 
Welded 
Crevice - 
Vapor Phase 
DCB019 
DCB020 
DCB021 (SA) 
DCB049 
DCB050 
DCB051 (SA) 
DCB079 
DCB080 
DCB081 (SA) 
DCB109 
DCB110 
DCB111 (SA) 
DCB139 
DCB140 
DCB141 (SA) 
DCB175 
DCB176 
DCB177 (SA) 
Welded 
Weight-Loss- 
Liquid Phase 
DWB022 
DWB023 
DWB024 
DWB062 
DWB063 
DWB064 
DWB092 
DWB093 
DWB094 
DWB132 
DWB133 
DWB134 
DWB148 DWB175 
Welded 
Crevice - 
Liquid Phase 
DCB022 
DCB023 
DCB024 (SA) 
DCB052 
DCB053 
DCB054 (SA) 
DCB082 
DCB083 
DCB084 (SA) 
DCB112 
DCB113 
DCB114 (SA) 
DCB142 
DCB143 
DCB144 (SA) 
DCB178 
DCB179 
DCB180 (SA) 
Source: DTN: LL030412512251.057 [DIRS 163712] (for all but surface analysis (SA) designated samples). 
NOTE: SA = Reserved for surface analyses (not subject to cleaning for weight-loss measurement or included 
in DTN: LL030412512251.057 [DIRS 163712]). 
All tests were carried out under ambient pressure. After approximately five years of exposure to 
each solution, the specimens were removed from their respective test vessels to determine their 
weight-loss. In all of the tested conditions, the coupons were covered with deposits. Therefore, 
the coupons were cleaned prior to final weighing. Cleaning was carried out according to 
ASTM G 1-90 (1999 [DIRS 103515]). For specimens exposed to simulated concentrated water 
and simulated dilute water, the posttest specimens were descaled for 2 minutes in a cleaning 
solution prepared by diluting 150 mL of concentrated HCl acid (37% HCl of specific gravity 
of 1.19) with deionized water to make 1,000 mL of solution (TIP-CM-51 [DIRS 169585]). The 
cleaning temperature was ambient. For specimens exposed to simulated acidified water, the 
posttest specimens were first exposed for 2 minutes to the same HCl solution used for descaling 
samples exposed to simulated concentrated water and simulated dilute water (TIP-CM-51 
[DIRS 169585]). The samples were then immersed at 95C for 2 minutes in a solution prepared 
by dissolving 200 g of NaOH and 30 g of KMnO4 in deionized water to make 1,000 mL of 
solution. Finally, the specimens were immersed for 3 minutes in a solution prepared by 
dissolving 100 g of diammonium citrate in deionized water to make 1,000 mL of solution. 
Weight-loss measurements and scanning electron microscopy analysis showed that these 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-27 October 2004 
cleaning methods removed all scale from tested samples, yet did not significantly affect untested 
foil samples (TIP-CM-51 [DIRS 169585]). Due to heavy deposits, some samples were cleaned 
multiple times before SEM photomicrographs indicated no remaining deposits. The only 
modifications to ASTM G 1-90 (1999 [DIRS 103515]) methods were an increased immersion 
time (found to be necessary for complete cleaning) and the use of a drying oven and desiccator to 
minimize air exposure (decreasing the amount of post cleaning film formation and increasing the 
measured weight-loss resulting in higher determined corrosion rates). 
6.4.3.2 Weight-Loss Data Analysis 
The general corrosion rate measurements are based upon ASTM G 1-90 (1999 [DIRS 103515]). 
The formula used to calculate the general corrosion rate from weight-loss data of the tested 
materials is shown in Equation 6-7: 
t A 
w Rate Corrosion 
  
.   = 
. 
9 10 6 . 87 (Eq. 6-7) 
where 87.6  109 is the proportionality constant (nm  cm-1  hour  year-1), w . is the weightloss 
in grams after 5+ years, . is the density of Alloy 22 (8.69 g/cm3) (Haynes International 1997 
[DIRS 100896], p. 13), A is the exposed surface area of each coupon (cm2), and t is the exposure 
time (hours). The exposed surface area A is calculated as follows: 
dc d ac bc ab A p p + . .. 
. 
. .. 
. 
- + + = 
2 
2 2 2 
2 
(Eq. 6-8) 
where a is the length of the specimen in cm, b is the width of the specimen in cm, c is the 
thickness of the specimen in cm, and d is the diameter of the hole in cm (Figure 6-9 provides a 
schematic of the sample coupon). 
a 
b 
c d 
A = exposed surface area in cm 2 
a = length of the specimen in cm 
b = width of the specimen in cm 
c = thickness of the specimen in cm 
d = diameter of hole in cm 
Figure 6-9. Schematic of Specimen Used in the Weight-Loss Measurements of Alloy 22 Samples in 
Long Term Corrosion Test Facility 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-28 October 2004 
Calculation of the exposed surface area of the weight-loss and crevice samples using 
Equation 6-8 included the area directly under the crevice former for the crevice samples and the 
area directly under the sample spacer for the weight-loss samples. These areas were included 
because the test solutions penetrated and wet the areas under the crevice former or sample 
spacer. The inputs from DTN: LL030412512251.057 [DIRS 163712] used in the model 
analysis were the weight-loss measurements and characteristics of the sample and exposure 
conditions. The calculated corrosion rates of the weight-loss and crevice coupons are listed in 
Appendices II and III, respectively. The calculated corrosion rates may differ slightly from those 
in the input DTN due to differences in the number of significant digits used in the calculations. 
As noted in Appendix II, Sample DCA177 is an outlier and was not included in the weight-loss 
data analysis and the WPOB general corrosion model analysis. The mean and standard deviation 
of all the 5-year crevice sample data including Sample DCA177 are 7.90 nm/yr and 7.09 nm/yr, 
respectively (output DTN: SN0306T0506303.004). Applying the Grubbs test for outliers as 
specified in Standard Practice for Dealing with Outlying Observations (ASTM E 178-02 2002 
[DIRS 169968]) the computed value for T60 (there are n = 60 general corrosion measurements of 
crevice samples listed in Appendix II) for the measured general corrosion rate of 
Sample DCA177 (46.68 nm/yr) is 5.469. From Table 1 in ASTM E 178-02 (2002 
[DIRS 169968]), and using n = 60, a T60 value as large as 5.469 would occur by chance with 
probability less than 0.001. Thus, the evidence is against the suspect value having come from the 
same population as the others (assuming the population is normally distributed). Therefore, the 
measured corrosion rate (46.68 nm/yr) of Sample DCA177 is beyond five standard deviations 
from the mean. In addition, the sample was tested in the vapor phase over the SDW solution, 
which is the least corrosive condition among the test conditions of the long-term weight-loss 
tests. The above arguments provide sufficient justification for exclusion of the outlier. 
Sample DWA089 yielded a negative corrosion rate and was conservatively excluded in the 
weight-loss analysis. 
Figure 6-10 and Figure 6-11 summarize the calculated corrosion rates for the Alloy 22 weightloss 
coupons and crevice coupons, respectively, exposed to the SAW, SCW, and SDW solutions 
at 60C and 90C for over five years. The mill-annealed (MA) and as-welded (ASW) samples 
were combined for the analyses. The average corrosion rates and two standard deviation ranges 
were calculated based on the use of a normal distribution and are presented in both figures. The 
2-standard deviation range represents a 95 percent confidence level. Although the appearance 
and amount of deposits on the coupons exposed to different solutions were different, the 
calculated corrosion rates were not significantly different. The individual corrosion rates for the 
weight-loss coupons ranged from about 0 to 12 nm/yr (Figure 6-16) with the lowest rates 
observed for the coupons in the SDW solution. The individual corrosion rates for the crevice 
coupons ranged from about 0 to 23 nm/yr (Figure 6-21) with the highest rates observed in the 
SAW solution and, again, the lowest rates observed in the SDW solution. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-29 October 2004 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-10. Corrosion Rates for Alloy 22 Weight-Loss Coupons in SAW, SCW, and SDW 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-11. Corrosion Rates for Alloy 22 Crevice Coupons in SAW, SCW, and SDW 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-30 October 2004 
In most cases, the crevice coupons exhibited corrosion rates 2 to 5 times higher than the 
weight-loss coupons in the same solutions. Stereomicroscopic and scanning electron 
microscopic (SEM) observations of weight-loss and crevice specimens indicated little or no sign 
of corrosion. The machining grooves remained uniform and sharp throughout each coupon. No 
crevice corrosion was observed on any of the tested coupons. It is possible that a different 
surface finish treatment used for the crevice samples may have led to measurement of different 
corrosion rates. However, it is noteworthy that among all test specimens, a maximum corrosion 
rate of only about 23 nm/yr was observed (Figure 6-21). 
For the weight-loss and crevice coupons, the corrosion rates were generally lower for specimens 
exposed to vapor than those immersed in liquid, regardless of the test temperature or electrolyte 
solution. Overall, the test coupons in the SAW solution at 90C exhibited slightly lower 
corrosion rates than at 60C. 
Similar to the weight-loss coupons, the corrosion rates for the crevice coupons exposed to liquid 
were lower at 90C than at 60C, while the corrosion rates were generally higher at 90C than 
at 60C for the crevice coupons exposed to vapor. In general, for corrosion processes, the 
corrosion rate increases with temperature. However, in this study, since the determined 
corrosion rates were very low and the temperature range studied (60C to 90C) was narrow, a 
clear dependence with the temperature could not be established for these data. For the 
weight-loss coupons, there was no effect of welds on the corrosion rate. The nonwelded crevice 
coupons exhibited slightly higher corrosion rates than their welded counterparts. 
The general corrosion rates of the coupons were analyzed with empirical cumulative 
distribution functions (ECDFs) of the calculated rates. In constructing the ECDFs, the 
cumulative probability values of the general corrosion rate (except the upper and lower bounds) 
were calculated by the following plotting positions (Cleveland 1993 [DIRS 163885], 
Section 2.1): 
n 
i qi 
5 . 0 - = (Eq. 6-9) 
where qi is the cumulative probability of the ith smallest event (e.g., general corrosion rate) and n 
is the total number of events. The above plotting position formula is a traditional choice for 
probability plotting (Stedinger et al. 1993 [DIRS 105941], Section 18.3.2). The ECDFs 
developed using the above plotting position formula for the 5-year weight-loss analysis are to 
present the data trends and comparative analysis of different sets of data for varying sample 
geometry and exposure conditions. 
The ECDFs for the general corrosion rates of the weight-loss specimens are shown in Figure 
6-12 to Figure 6-16 for comparative analyses of the effect of various experimental conditions, 
such as solution chemistry, temperature, and metallurgical condition, on the general corrosion 
rate. The ECDFs for the general corrosion rates of the crevice coupons are shown in Figure 6-17 
to Figure 6-21 for comparative analyses of the effect of various experimental conditions on the 
general corrosion rate. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-31 October 2004 
ECDF - 5-year Alloy 22 Weight-Loss Samples 
60C vs. 90C 
0.00 
0.25 
0.50 
0.75 
1.00
0 2 4 6 8 10 12 14 
General Corrosion Rate (nm/year) 
Cumulative Probability
60 C 
90 C 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-12. Empirical Cumulative Distributions for General Corrosion Rate of Alloy 22 Weight-Loss 
Samples at 60C and 90C after 5-Year Exposure in the LTCTF 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-13. Empirical Cumulative Distributions for General Corrosion Rate of Alloy 22 Weight-Loss 
Samples Exposed in the Vapor Phase and Aqueous Phase after 5-Year Exposure in the 
LTCTF 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-32 October 2004 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-14. Empirical Cumulative Distributions for General Corrosion Rate of Mill-Annealed and As- 
Welded Alloy 22 Weight-Loss Samples After 5-Year Exposure in the LTCTF 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-15. Empirical Cumulative Distributions for General Corrosion Rate of Alloy 22 Weight-Loss 
Samples Tested in Three Different Solution Types After 5-Year Exposure in the LTCTF 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-33 October 2004 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-16. Empirical Cumulative Distributions for General Corrosion Rate of All Alloy 22 Weight-Loss 
Samples after 5-Year Exposure in the LTCTF 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-17. Empirical Cumulative Distributions for General Corrosion Rate of Alloy 22 Crevice Samples 
at 60C and 90C after 5-Year Exposure in the LTCTF 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-34 October 2004 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-18. Empirical Cumulative Distributions for General Corrosion Rate of Alloy 22 Crevice Samples 
Exposed in the Vapor Phase and Aqueous Phase after 5-Year Exposure in the LTCTF 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-19. Empirical Cumulative Distributions for General Corrosion Rate of Mill-Annealed and As- 
Welded Alloy 22 Crevice Samples after 5-Year Exposure in the LTCTF 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-35 October 2004 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-20. Empirical Cumulative Distributions for General Corrosion Rate of Alloy 22 Crevice Samples 
Tested in Three Different Solution Types after 5-Year Exposure in the LTCTF 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-21. Empirical Cumulative Distributions for General Corrosion Rate of All Alloy 22 Crevice 
Samples after 5-Year Exposure in the LTCTF 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-36 October 2004 
The ECDFs for the general corrosion rates of all the weight-loss and crevice samples, regardless 
of the test medium or temperature, are shown in Figure 6-22. For the crevice samples the mean 
corrosion rate is 7.24 nm/yr, and the standard deviation is 4.98 nm/yr. For the weight-loss 
samples the mean corrosion rate is 2.75 nm/yr and the standard deviation is 2.74 nm/yr. These 
are discussed in Section 6.4.3.3 and summarized in Table 6-6. The corrosion rate distribution for 
the crevice coupons was used as the base-case general corrosion rate of the WPOB. 
Section 6.4.3.4 provides details of the base-case general corrosion model. 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-22. Empirical Cumulative Distributions for General Corrosion Rate of Alloy 22 Weight-Loss and 
Crevice Samples after 5-Year Exposure in the LTCTF 
6.4.3.3 Uncertainty Analysis of General Corrosion Rate Data 
As discussed in Section 6.4.3.4, the 5-year data were used for the base-case general corrosion 
model for the WPOB. Therefore, it is important to adequately quantify the uncertainty associated 
with the data and propagate it into the general corrosion model. This section documents the 
analyses performed to quantify the uncertainty in the general corrosion rates of Alloy 22 
calculated from the LTCTF 5-year weight-loss measurements. Most of the uncertainty results 
from insufficient resolution of the weight-loss measurements of the samples due to the extremely 
low corrosion rates of the alloy in the test media. Measurement uncertainty was the main source 
of uncertainty. The method used in measurement uncertainty analysis is presented in this 
section. The method enables sound interpretation of the general corrosion data shown in Figure 
6-22 (also in Appendices II and III) and its application in the waste package degradation 
analysis. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-37 October 2004 
Consider a measurand Y, which is not measured directly, but determined from N other quantities 
X1, X2 ,..., XN through a functional relationship f defined as follows: 
), , , ( 2 1 N X X X f Y    = (Eq. 6-10) 
An estimate of the measurand Y, denoted by y, is obtained using input estimates x1, x2 ,..., xN for 
the values of N input quantities N X X X , , , 2 1    . The output estimate y, is given by: 
), , , ( 2 1 N x x x f y    = (Eq. 6-11) 
The combined uncertainty of the measurement result y, designated by .y , is given by 
Equation 6-12, the law of propagation of uncertainty (Taylor et al. 1994 [DIRS 162260], 
Appendix A): 
.y = .f 
.xi 
. 
. 
. 
. 
. 
. 
2
.xi
2 + 2 .f 
.xi 
.f 
.xj 
.xixj 
j=i+1 
N.
i=1 
N-1 . 
i=1 
N. 
(Eq. 6-12) 
In Equation 6-12, the partial derivatives .f 
.xi 
are the sensitivity coefficients, .xi is the standard 
uncertainty associated with the input estimate xi, and .xixj is the estimated covariance 
associated with xi and xj. 
Referring to Figure 6-9, the schematic of the Alloy 22 sample used in the weight-loss 
measurement in LTCTF, the exposed surface area of the sample is expressed as follows: 
dc d ac bc ab A p p + . .. 
. 
. .. . 
- + + = 
2 
2 2 2 
2 
(Eq. 6-13) 
Referring to Equation 6-7 and letting the dependent variable y be the 5-year general corrosion 
rate measured in the LTCTF, the equation for the general corrosion rate is expressed as follows: 
. .. 
. 
. .. 
. 
+ . .. 
. 
. .. 
. 
- + +  
= = 
dc d ac bc ab t 
w 
dt 
dp y 
p p . 
2 
2 2 2 
2 (Eq. 6-14) 
where y is the corrosion rate in cm per hour, t is the time of exposure in hours, w is the total 
weight-loss during the time, t, in grams, and . is the density in grams per cubic centimeter. The 
combined uncertainty of the measurement result, y, the corrosion rate, is calculated using the law 
of propagation of uncertainty (Taylor et al. 1994 [DIRS 162260], Appendix A): 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
d 
d
y c 
c
y b 
b
y a 
a
y t 
t
y y w 
w
y y . .. 
. 
.. 
. + . .. 
. 
.. 
. + . .. 
. 
.. 
. + . .. 
. 
.. 
. + . .. 
. 
.. 
. + . . .. 
. 
. .. 
. 
+ . .. 
. 
.. 
. = . 
.
. 
.
. 
.
. 
.
. 
.
. . 
.. 
. 
.
. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-38 October 2004 
(Eq. 6-15) 
where w, ., t, a, b, c, and d were considered to be independent; hence, the covariance terms 
disappear. 
The partial derivatives are: 
. .
.
. 
. .
.
. 
+ . .. 
. 
. .. 
. 
- + +  
= 
dc d ac bc ab t 
w
y 
p p . 
.
. 
2 
2 2 2 
1 
2 (Eq. 6-16) 
. .. 
. 
. .. 
. 
+ . .. 
. 
. .. 
. 
- + +  
- = 
dc d ac bc ab t 
w y 
p p . 
.. 
. 
2 
2 2 2 
2 
2 
(Eq. 6-17) 
. .. 
. 
. .. 
. 
+ . .. 
. 
. .. 
. 
- + +  
- = 
dc d ac bc ab t 
w 
t
y 
p p . 
.
. 
2 
2 2 2 
2 
2 
(Eq. 6-18) 
2 2 
2 
2 2 2 
) ( 2 
. .
.
. 
. .
.
. 
+ . .. 
. 
. .. 
. 
- + +  
+ - = 
dc d ac bc ab t 
c b w 
a
y 
p p . 
.
. (Eq. 6-19) 
2 2 
2 
2 2 2 
) ( 2 
. .
.
. 
. .
.
. 
+ . .. 
. 
. .. 
. 
- + +  
+ - = 
dc d ac bc ab t 
c a w 
b
y 
p p . 
.
. (Eq. 6-20) 
2 2 
2 
2 2 2 
] ) ( 2 [ 
. .. 
. 
. .. 
. 
+ . .. 
. 
. .. 
. 
- + +  
+ + - = 
dc d ac bc ab t 
d b a w 
c
y 
p p . 
p 
.
. (Eq. 6-21) 
2 2 
2 
2 2 2 
) ( 
. .
.
. 
. .
.
. 
+ . .. 
. 
. .. 
. 
- + +  
- - = 
dc d ac bc ab t 
d c w 
d
y 
p p . 
p 
.
. (Eq. 6-22) 
The maximum error in the corrosion rate is estimated by calculating numeric values of the partial 
derivatives from expected values of the independent variables, multiplying each partial 
derivative by the corresponding error (i.e., standard uncertainty) associated in the independent 
variables ( .w, .., .t, .a, .b, .c, and .d), and summing the resulting products. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-39 October 2004 
The combined standard uncertainty in the corrosion rate was estimated with Equation 6-15 by 
calculating numeric values of the partial derivatives from expected values of the input variables 
and their estimated standard uncertainties. Those values and intermediate calculation steps are 
summarized in Table 6-5. 
Upon examining the sensitivity coefficients in Equation 6-15, it was found that .y was most 
sensitive to the estimate of .w. Because .w was most influential on .y, a detailed description of 
how .w was calculated is given below. The Mettler AT200 balance was used to measure the 
weight of the specimens. The balance displays mass measurements to four decimal places. For 
instance, a four-digit readout might indicate a mass of 60.2675 grams for the weight of a 
specimen. If the balance employs standard round-off practice, then the displayed number is 
derived from a value that lies between 60.26745 grams and 60.26755 grams. The mass has an 
equal probability of lying between those two numbers. This would indicate that the error term 
has a uniform distribution. If w1 = original weight of specimen and w2 = final weight of 
specimen, then w1 = 1 
+10-4 e1 
and w2 = 2 
+10-4 e2 
. That is, the mass = true mass + error term, 
and e1 
~U(-0.5,0.5), and e2 
~U(-0.5,0.5). The weight-loss due to corrosion is: 
w = w1 -w2 = ( 1 
- 2 
)+10-4 ( e1 
- e2 
) (Eq. 6-23) 
where ( 1 
- 2 
) is the true difference in mass and 10-4 ( e1 
- e2 
) is the error term. The error 
term ( e1 
- e2 
) has a triangular distribution (Papoulis 1965 [DIRS 162236], pp. 189 to 192) 
between 1 and 1 (i.e., ( e1 
- e2 
) ~ Triangular (-1, 1, 0)). For this distribution the standard 
deviation is: 
s = 1
6 
= 0.41 (Eq. 6-24) 
Therefore, .w = 0.41  10-4 g. The summary of the measurement uncertainty analysis for the 
5-year data based upon this method is shown in Table 6-6. 
Table 6-5. Summary of Measurement Uncertainty Analysis for Corrosion Rates Based Upon Weight- 
Loss Measurements after 5-Year Exposure in LTCTF 
Uncertainty Analysis of 5-Year Weight-Loss Measurement Data 
Parameters Units Crevice Samples Weight-Loss Samples 
w g 0.00187 0.00036 
. g/cm3 8.69 8.69 
t hour 43,800 43,800 
a cm 5.08 5.08 
b cm 5.08 2.54 
c cm 0.3048 0.3048 
d cm 0.7925 0.7925 
.w g 4.100E-05 4.100E-05 
.. g/cm3 0.1 0.1 
.t hour 24 24 
.a cm 0.00254 0.00254 
.b cm 0.00254 0.00254 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-40 October 2004 
Uncertainty Analysis of 5-Year Weight-Loss Measurement Data 
Parameters Units Crevice Samples Weight-Loss Samples 
.c cm 0.00254 0.00254 
.d cm 0.00254 0.00254 
Surface Area cm2 57.5787 30.2239 
.y/.w 4.563E-08 8.693E-08 
.y/.. -9.819E-12 -3.601E-12 
Table 6-5. Summary of Measurement Uncertainty Analysis for Corrosion Rates Based Upon Weight- 
Loss Measurements after 5-Year Exposure in LTCTF 
Uncertainty Analysis of 5-Year Weight-Loss Measurement Data 
Parameters Units Crevice Samples Weight-Loss Samples 
.y/.t -1.948E-15 -7.145E-16 
.y/.a -1.596E-11 -5.891E-12 
.y/.b -1.596E-11 -1.115E-11 
.y/.c -3.011E-11 -1.578E-11 
.y/.d 2.271E-12 1.586E-12 
(.y/.w)2.w2 3.500E-24 1.270E-23 
(.y/..)2..2 9.641E-25 1.297E-25 
(.y/.t)2.t2 2.186E-27 2.940E-28 
(.y/.a)2.a2 1.643E-27 2.239E-28 
(.y/.b)2.b2 1.643E-27 8.022E-28 
(.y/.c)2.c2 5.850E-27 1.606E-27 
(.y/.d)2.d2 3.326E-29 1.624E-29 
.y cm/hr 2.116E-12 3.583E-12 
.y m/yr 1.853E-04 3.138E-04 
.y nm/yr 0.185 0.314 
Output DTN: MO0409MWDUGCMW.000. 
Table 6-6. Summary of Measurement Uncertainty Analysis for Corrosion Rates Based on Weight-Loss 
Measurements after 5-Year Exposure in LTCTF 
Sample Configuration Average 
Weight Loss .y Mean Corrosion 
Rate 
Standard 
Deviation 
(g) (nm/yr) (nm/yr) (nm/yr) 
Weight-Loss Samples 0.00036 0.314 2.75 2.74 
Crevice Samples 0.00187 0.185 7.24 4.98 
Output DTN: MO0409MWDUGCMW.000. 
The combined standard uncertainty is estimated to be approximately 0.185 nm/yr in the case of 
crevice samples and 0.314 nm/yr in the case of weight-loss samples. These estimates correspond 
to one standard deviation (1 s). Therefore, for the crevice samples, about 3 percent of the 
variation in the measured general corrosion rate is due to the measurement uncertainty, 
and 97 percent of it is from the variations of the corrosion rate among the specimens. For the 
weight-loss samples, most of the variation (about 89 percent) in the measured corrosion rate is 
due to variations among the specimens, and the rest is from measurement uncertainty. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-41 October 2004 
As discussed in the base-case conceptual model in Section 6.3, mineral deposits and scales could 
form on the waste package surface from evaporative concentration of the water in contact with 
the constituents such as dust and salts present on the surface. Crevices could form between the 
deposits and waste package. Therefore, the corrosion rate distribution determined from the 
creviced geometry samples was used for the base-case general corrosion rate of the WPOB 
(a conservative approach). Furthermore, because only a small amount (about 3 percent) of the 
total variation in the measured general corrosion rate of the crevice samples is due to the 
measurement uncertainty, all (100 percent) of the measured variation is considered to be due to 
the variability in the general corrosion processes for modeling purposes. The general corrosion 
rate variability is applied among modeled waste packages and among local areas on a waste 
package surface. 
6.4.3.4 Base-Case Temperature-Dependent General Corrosion Model 
The general corrosion (passive dissolution) of highly corrosion-resistant alloys such as Alloy 22 
is governed by the transport properties of reacting species in the passive film and the dissolution 
rate of the passive film. The reacting species include metal ions, oxygen ions, vacancies and 
interstitials. These processes are influenced by the characteristics of the passive film, 
electrochemical potential across the film, and the chemistry of solution contacting the film 
(BSC 2001 [DIRS 155950], Section 7.3.5.1). Chromium and nickel oxides, which are the major 
constituents of the passive film of nickel-chromium-molybdenum alloys like Alloy 22 (Lorang et 
al. 1990 [DIRS 154718]), are stable and exhibit extremely low dissolution rates over a wide 
range of solution chemistry. The transport properties of the reacting species and reaction rates in 
the passive film are considered thermally activated processes. The general corrosion rate of the 
Alloy 22 waste package outer barrier is expected to have a certain level of temperature 
dependency (BSC 2001 [DIRS 155950], Section 7.3.5.1). The literature data summarized in a 
recent report by the Electric Power Research Institute (EPRI 2002 [DIRS 158069], Section 5.3.2) 
show such a temperature-dependence of Alloy 22 general corrosion rates in a wide range of test 
solution chemistries. 
The general corrosion rate at a given temperature is represented by an Arrhenius relation in 
logarithmic form, i.e.: 
T
C C R o T 
1 ) ln( + = (Eq. 6-25) 
where RT is temperature-dependent general corrosion rate in nm/yr, T is the absolute temperature 
in Kelvin, and Co and C1 (in Kelvin) are constants. 
The temperature-dependence term (C1) is determined from the corrosion rates obtained from the 
short-term polarization resistance data for Alloy 22 specimens tested for a range of sample 
configurations, metallurgical conditions, and exposure conditions (temperature and water 
chemistry). The intercept term, Co, is determined from the value of C1 and the distribution of 
measured general corrosion rates. 
The polarization resistance of the samples was measured after 24-hour exposure of the samples 
in open-circuit potential in the test environments (Section 4.1.1.4, Appendix I). Polarization 
resistance is an acceptable technique for obtaining the temperature dependence of corrosion 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-42 October 2004 
reactions. Polarization resistance technique is rapid, simple, and relatively inexpensive 
(Revie 2000 [DIRS 159370], Chapter 68). The technique is well established for routine use and 
is described in ASTM G 59-97 (1998 [DIRS 163907]). The details of the polarization resistance 
measurements used in this report are discussed in Appendix I. The relative change in corrosion 
rate, rather than the absolute values of the corrosion rates, with temperature is used in this report 
to determine the temperature dependence used in the model. In this way, any error in the 
measured corrosion rate has a lesser impact on the model results. 
Although some investigators have observed an effect of scan rate on polarization resistance 
measurements on Alloy 22 (Pensado et al. 2002 [DIRS 166944], Section 4.2) and recommended 
the use of a slower scan rate, the experiments in this report were conducted following 
ASTM G 59-97 (1998 [DIRS 163907]), which recommends the use of a potential scan sweep 
rate of 0.6 V/hr (0.167 mV/sec). This potential scan sweep rate was used for the polarization 
resistance measurements at all temperatures discussed in this report. The corrosion rates from the 
polarization resistance measurements were for a comparative analysis to extract the temperature 
dependence of the general corrosion rates (i.e., to obtain a relative measure of how corrosion 
rates change with temperature). The measurements were not intended for obtaining the absolute 
values of the general corrosion rate. The method for obtaining absolute values of the general 
corrosion rates of Alloy 22 is discussed later in this section. 
Temperature Dependence of MA Alloy 22 Corrosion 
(Corrosion Rates from Polarization Resistance Measurements) 
1.E+01 
1.E+02 
1.E+03 
1.E+04 
1.E+05 
2.0E-03 2.2E-03 2.4E-03 2.6E-03 2.8E-03 3.0E-03 3.2E-03 3.4E-03 
1/T (1/K) 
Corrosion Rate (nm/year) 
MA MCA 1M NaCl 
MA MCA 1.25M NaCl 
MA MCA 1.25M CaCl2 
MA MCA 2.5M CaCl2 
MA MCA 5M CaCl2 
MA MCA 7M CaCl2 
MA Disc 7M CaCl2 
MA Disc 8M CaCl2 
MA Disc 9M CaCl2 
MA MCA 1.25M CaCl2, NO3/Cl=0.01 
MA MCA 1.25M CaCl2, NO3/Cl=0.1 
MA MCA 5M CaCl2, NO3/Cl=0.1 
MA Disc 6M CaCl2, NO3/Cl=0.1 
MA MCA 7M CaCl2, NO3/Cl=0.1 
MA Disc 7M CaCl2, NO3/Cl=0.1 
MA MCA 8M CaCl2, NO3/Cl=0.1 
MA Disc 9M CaCl2, NO3/Cl=0.1 
MA MCA 9M CaCl2, NO3/Cl=0.1 
Trendline for All Data 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-23. Temperature Dependence of Corrosion Rates of Mill-Annealed Alloy 22 Samples Obtained 
from Polarization Resistance Measurements for Varying Sample Configurations in a Range 
of Solution Chemistries 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-43 October 2004 
Figure 6-23 shows the temperature dependence of corrosion rates of mill-annealed (MA) 
Alloy 22 samples over the temperature range from 45C to 170C. Figure 6-24 shows the 
corrosion rates for the as-welded (ASW) samples and as-welded plus thermally aged samples 
over the temperature range from 75C to 124C. The aged samples were treated for 173 hours 
at 700C prior to the electrochemical testing. A trend line was drawn for the data in each figure 
for better visualization of the temperature dependence of the corrosion rates. The numerical 
corrosion rate data are listed in Appendix IV. 
Temperature Dependence of ASW and ASW+Aged Alloy 22 Corrosion 
(Corrosion Rates from Polarization Resistance Measurements) 
1.E+01 
1.E+02 
1.E+03 
1.E+04 
1.E+05 
2.2E-03 2.4E-03 2.6E-03 2.8E-03 3.0E-03 3.2E-03 
1/T (1/K) 
Corrosion Rate (nm/year) 
ASW Prism 1M NaCl 
ASW MCA 5M CaCl2 
ASW MCA 1M CaCl2, NO3/Cl=1 
ASW MCA 5M CaCl2, NO3/Cl=0.01 
ASW Prism 5M CaCl2, NO3/Cl=0.1 
ASW MCA 5M CaCl2, NO3/Cl=0.2 
ASW+Aged MCA 5M CaCl2 
ASW+Aged MCA 1M CaCl2, NO3/Cl=1 
ASW+Aged MCA 5M CaCl2, NO3/Cl=0.01 
ASW+Aged MCA 5M CaCl2, NO3/Cl=0.1 
Trendline for All Data 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-24. Temperature Dependency of Corrosion Rates of As-Welded and As-Welded Plus 
Thermally Aged Alloy 22 Samples Obtained from the Polarization Resistance 
Measurements for Varying Sample Configurations in a Range of Solution Chemistries 
This model approach is justified because, as discussed in Section 7.2, the activation energies of 
general corrosion rate of highly corrosion-resistant Ni-Cr-Mo alloys are similar regardless of the 
exposure time in the test environments. That is, the literature data presented in Section 7.2 
demonstrate that the temperature dependence of general corrosion rate of Alloy 22 does not 
change significantly as the general corrosion rate decreases with the exposure time. 
Although there is a spread of the data for a given temperature, Figure 6-23 and Figure 6-24 
clearly show a consistent trend of the temperature dependence of the corrosion rates measured by 
the polarization resistance. It is also shown that the corrosion rates of the ASW and ASW plus 
thermally aged samples (Figure 6-24) are comparable to those of the MA samples Figure 6-23. 
There are no significant differences in the 24-hour corrosion rates for the samples with different 
metallurgical conditions (i.e., MA, ASW, and ASW plus thermally aged). See Section 6.4.6 for 
detailed discussion on the effect of aging on the WPOB corrosion. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-44 October 2004 
The corrosion rate data for all the samples with the three different metallurgical conditions were 
used together for the analysis of the temperature dependence of the WPOB general corrosion 
because their corrosion rates as obtained by the polarization resistance method are comparable. 
From fitting the data (listed in Appendix IV) to Equation 6-25, the temperature-dependence term, 
C1, was determined. C1 has a mean of 3,116.47 K and a standard deviation of 296.47 K. 
A normal distribution was used for the parameter in the regression analysis. Further analysis of 
the residuals showed that the errors are normally distributed. Rearranging Equation 6-25 to the 
form of the Arrhenius relation (i.e., RT = A exp(-Ea/RT)), C1 can be expressed as -Ea/R, where Ea 
is the activation energy (J/mol), and R is the universal gas constant (8.314 Jmol-1K-1). This 
temperature dependence corresponds to an activation energy of 25.91  2.46 kJ/mol. The data for 
the MCA samples with their edges not polished were not included in the regression analysis for 
the temperature dependence (Section 4.1.1.4). 
The general corrosion rate distribution determined from the weight-loss data of the 5-year 
crevice specimens measured at both 60C and 90C (Figure 6-17) represents the distribution of 
long-term general corrosion rates of the WPOB at 60C for the purposes of this model. This 
approach is reasonably bounding because the general corrosion rates for crevice specimens are 
generally higher than those of noncreviced weight-loss specimen. The intercept term, Co, can be 
determined from the temperature-dependence term, C1, as follows: 
0
1 ) ln( 
T
C C R o o + = (Eq. 6-26) 
0
1 ) ln( 
T
C R C o o - = (Eq. 6-27) 
where Ro is the general corrosion rate distribution from the weight loss of the 5-year crevice 
samples (Figure 6-22) in nm/yr at T0 = 333.15 K (60C). Substituting for Co in Equation 6-25, 
results in: 
.. 
. 
.. 
. - + = 
15 . 333
1 1 ) ln( ) ln( 1 T 
C R R o T (Eq. 6-28) 
The entire variance of the temperature dependence term, C1, is due to uncertainty, and the 
uncertainty is limited to  3 standard deviations. This treatment appropriately reflects the lack of 
knowledge in the exact value to the temperature dependence term and incorporates 99.7 percent 
of the data variance ( 3 standard deviations). 
The 5-year corrosion rate data for Alloy 22 were analyzed to determine the theoretical 
distribution that best fits the data. The following three goodness-of-fit tests were performed for 
the data analysis: the Chi-Square test, the Kolmogorov-Smirnov test, and the Anderson-Darling 
test. All the statistical tests indicated that the Weibull distribution best fits the 5-year corrosion 
rate data. Therefore, it was decided to use a Weibull distribution. To estimate the parameters of 
the Weibull distribution, the method of Maximum Likelihood Estimator was used. A Weibull 
distribution, with scale factor, s = 8.88 nm/yr; shape factor, b = 1.62; and location 
factor, l = 0 nm/yr best fits the corrosion rate distribution. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-45 October 2004 
Therefore, Ro is expressed as an inverse Weibull CDF as follows (Evans et al. 1993 
[DIRS 112115], p. 154): 
b 
o p 
s R 
/ 1 
1 
1 ln .. 
. 
.. 
. 
. .. 
. 
. .. 
. 
- 
= (Eq. 6-29) 
where p is the cumulative probability, and s and b were defined and their values were given 
above. The cumulative distribution function of Ro is given in Figure 6-25 along with the crevice 
sample data (Figure 6-22). The 99.99th percentile rate (a reasonable upper-bound value) of 
Ro is 35 nm/yr. This value is greater than the measured maximum rate of 23 nm/yr for the 
crevice samples (Section 6.4.3.2). 
The model outputs (RT) at temperatures of 25C, 50C, 75C, 100C, 125C and 150C are 
shown in Figure 6-26. The model results shown in the figure are for the mean value of the 
temperature dependence term (C1) and having the entire variance of Ro due to the variability in 
the general corrosion process (Table 6-6 and associated discussions above for additional details 
on the basis for the corrosion rate variability). Figure 6-27 and Figure 6-28 show the cumulative 
distribution functions (CDFs) of the model outputs (RT) at temperatures of 25C, 50C, 75C, 
100C, 125C, and 150C for the upper bound activation energy of 33.29 kJ/mol and the lowerbound 
activation energy of 18.53 kJ/mol, respectively. The model results for the elevated 
temperatures assume the passivity of the alloy is maintained at those temperatures. Therefore, 
the cumulative distribution functions of the model calculated general corrosion rates in the figure 
represent the range of the variable general corrosion rates of the WPOB at each exposure 
temperature of interest, with the mean C1 value. 
The model results show that the uncertainty range of the 50th percentile general corrosion rate 
at 25C is from 1.7 to 3.2 nm/yr (mean 2.4 nm/yr), and that of the 99th percentile rate is from 
5.6 to 10.4 nm/yr (mean 7.6 nm/yr) (Figure 6-26 to Figure 6-28). For 100C, the uncertainty 
range of the 50th percentile general corrosion rate is from 14.5 to 25.7 nm/yr (mean 19.3 nm/yr), 
and that of the 99th percentile rate is from 46.7 to 82.7 nm/yr (mean 62.1 nm/yr) (Figure 6-26 to 
Figure 6-28). In addition, for 150C and assuming the passivity of the alloy is maintained, the 
uncertainty range of the 50th percentile general corrosion rate is from 29.4 to 91.3 nm/yr (mean 
51.8 nm/yr), and that of the 99th percentile rate is from 94.6 to 294 nm/yr (mean 167 nm/yr) 
(Figure 6-26 to Figure 6-28). 
For a constant waste package surface temperature of 150 C and assuming the WPOB maintains 
the passivity, the total penetration depth by general corrosion over the regulatory period, using 
the 50th percentile general corrosion rate of 51.8 nm/yr for the mean activation energy 
(25.91 kJ/mol) (Figure 6-26), is only 518 m (about 0.5 mm). Using the 99.99th percentile rate 
(a reasonable upper bound rate) of 256 nm/yr at 150C for the mean activation energy (Figure 
6-26), the total penetration depth by general corrosion is only 2,560 m (about 2.6 mm). For the 
upper bound activation energy (33.29 kJ/mol) (Figure 6-27), the total penetration depth by 
general corrosion over the regulatory period at an exposure temperature of 150C, using the 50th 
percentile general corrosion rate (91.3 nm/yr) is 913 m (about 0.9 mm), and the total 
penetration depth using the 99.99th percentile general corrosion rate (451 nm/yr) is 4,510 m 
(about 4.5 mm). This bounding analysis clearly demonstrates that the waste package 
performance is not limited by general corrosion. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-46 October 2004 
Equation 6-28 is the base-case general corrosion model for the WPOB. As stated above, the 
entire variance of Ro represents the variability of the general corrosion process. The general 
corrosion rate variability represented by the parameter is applied among the waste packages to be 
modeled and to local areas on an individual waste package. As discussed above, the entire 
variance of the temperature dependence term (C1) is due to uncertainty, and the uncertainty is 
limited to  3 standard deviations. 
Cumulative Distribution Function of Base Case Ro 
With All Crevice Sample Data 
0.0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1.0 
1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 
General Corrosion Rate (nm/year) 
Cumulative Probability 
Base Case Ro CDF 
Crevice Sample Data 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-25. Cumulative Distribution Function (CDF) of Ro of the Base-Case Temperature-Dependent 
General Corrosion Model of the Waste Package Outer Barrier with All Crevice Sample Data 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-47 October 2004 
General Corrosion Rate CDF at Different Temperatures 
(Mean C1 = -3116.47 K) 
0.0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1.0 
1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 
General Corrosion Rate (nm/yr) 
Cumulative Probability 
25C 
50C 
75C 
100C 
125C 
150C 
Output DTN: MO0409MWDUGCMW.000. 
NOTE: The calculations were performed using the mean value (-3,116.47 K) of the temperature-dependence term 
(C1), and the calculated general corrosion rate ranges represent the variability of the rate. 
Figure 6-26. Calculated Model Outputs of the Base-Case Temperature-Dependent General Corrosion 
Model with the Mean Activation Energy of 25.91 kJ/mol at 25C, 50C, 75C, 100C, 
125C, and 150C 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-48 October 2004 
General Corrosion Rate CDFs at Different Temperatures 
(Upper Bound C1 = -4005.88 K) 
0.0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1.0 
1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 
General Corrosion Rate (nm/yr) 
Cumulative Probability 
25C 
50C 
75C 
100C 
125C 
150C 
Output DTN: MO0409MWDUGCMW.000. 
NOTE: The calculations were performed using the upper-bound value (-4,005.88 K) of the temperature-dependence 
term (C1), and the calculated general corrosion rate ranges represent the variability of the rate. 
Figure 6-27. Calculated Model Outputs of the Base-Case Temperature-Dependent General Corrosion 
Model with the Upper-Bound Activation Energy of 33.29 kJ/mol at 25C, 50C, 75C, 
100C, 125C, and 150C 
General Corrosion Rate CDFs at Different Temperatures 
(Lower Bound C1 = -2227.06 K) 
0.0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1.0 
1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 
General Corrosion Rate (nm/yr) 
Cumulative Probability 
25C 
50C 
75C 
100C 
125C 
150C 
Output DTN: MO0409MWDUGCMW.000. 
NOTE: The calculations were performed using the lower-bound value (-2,227.06 K) of the temperature-dependency 
term (C1), and the calculated general corrosion rate ranges represent the variability of the rate. 
Figure 6-28. Calculated Model Outputs of the Base-Case Temperature-Dependent General Corrosion 
Model with the Lower-Bound Activation Energy of 18.53 kJ/mol at 25C, 50C, 75C, 
100C, 125C, and 150C 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-49 October 2004 
6.4.3.5 Alternative Conceptual Model for General Corrosion 
Alternative conceptual models (ACMs) are based on modeling assumptions and simplifications 
different from those employed in the base-case model. An important reason for considering 
ACMs is to help build confidence that changes in modeling assumptions or simplifications will 
not change conclusions regarding subsystem and total system performance. Conceptual model 
uncertainty results from sparse observational data and a lack of available information to 
corroborate or refute plausible alternative interpretations of the subsystem and the processes 
occurring within the subsystem. This section discusses the ACMs for the general corrosion 
models of the WPOB. None of the general corrosion ACMs discussed in this section are 
included in the TSPA-LA. 
6.4.3.5.1 Time-Dependent General Corrosion Behavior of the Waste Package Outer 
Barrier 
As discussed in detail in Section 6.4.3.4, the base-case general corrosion model for the WPOB is 
based on the five-year weight-loss measurements of Alloy 22 crevice samples from the LTCTF. 
The general corrosion rate is temperature dependent, and for a given temperature, it is assumed 
constant (time independent) (Assumption 5.2). Therefore, for a given temperature, the depth of 
penetration or thinning of the WPOB by general corrosion is equal to the general corrosion rate 
at that temperature, multiplied by the time duration that the waste package surface is at that 
temperature. However, general corrosion rates of metals and alloys tend to decrease with time. 
Table 7-1, where general corrosion rates determined from potentiostatic polarization, 
polarization resistance, and weight-loss measurements are presented, shows a marked decrease in 
corrosion rate with time from 1 day to 2.3 years (the 5-year data point is excluded from this 
discussion for model validation purposes). Figure 7-1 shows that even if the 5-year data point 
were excluded from the figure, general corrosion rates for Alloy 22 decrease with time. 
Section 7.2 discusses that the trend of decreasing general corrosion rate with time is consistent 
with the expected corrosion behavior of passive alloys such as Alloy 22 under repository-type 
aqueous conditions. 
The time-dependent general corrosion behavior of the WPOB was not included in the TSPA-LA 
because the constant (time-independent) rate model (for a given temperature) is more 
conservative and will bound the general corrosion behavior of the WPOB over the repository 
time period. 
6.4.3.5.2 Alternative Conservative Interpretation of Long-Term General Corrosion Rates 
of Crevice Samples 
As shown in Figure 6-22, the general corrosion rates of the crevice samples are higher than those 
of the plain weight-loss samples. This may have been caused by different surface polishing 
treatments between the two sample groups. Another supposition is that there might have been 
higher corrosion rates in the creviced area under the crevice former. Figure 6-29 provides a 
schematic diagram of the crevice sample geometry. One modeling assumption made in this 
section, is that the corrosion rate of the boldly exposed (noncrevice) area of the crevice samples 
can be represented by the average corrosion rate of the weight-loss geometry samples. Using 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-50 October 2004 
this modeling assumption, the following data manipulations were made to estimate the corrosion 
rate of the crevice area under the crevice former. 
 The average weight loss per unit area of weight-loss geometry samples was calculated. 
 The true weight loss of the boldly exposed area of the crevice samples was estimated 
by multiplying the average weight loss per unit area (from the weight-loss geometry 
samples above) by the boldly exposed area of the crevice samples. 
 The weight loss from the crevice area under the crevice former was determined by 
subtracting the true weight loss of the boldly exposed area from the total weight loss 
measured for the crevice samples. 
 The corrosion rate of the crevice-area-only (the area under the crevice former) was 
calculated using the calculated weight loss from the crevice area. 
The empirical CDF of the estimated corrosion rates of the crevice-area-only under the crevice 
former is shown in Figure 6-30, along with the empirical CDFs of the weight-loss samples and 
crevice samples for comparison. The median corrosion rate (50th percentile rate) of the 
crevice-area-only is 51 nm/yr and is about 10 times the mean of the crevice samples. The 
maximum rate (100th percentile rate) of the crevice area only case is about 214 nm/yr, which is 
also about 10 times of the maximum rate of the crevice samples. Because the calculated 
corrosion rates of the crevice area under the crevice former are much higher than those of the 
boldly exposed area of the crevice samples, microscopic examinations would be able to show the 
differences in the corrosion fronts between the two areas (or at least at the edge of the area under 
the crevice former). However, examinations by optical microscopy and SEM did not reveal such 
differences. 
As with the crevice sample case, it was decided to use a Weibull distribution for Ro. The method 
of Maximum Likelihood Estimator was used to estimate the parameters of the Weibull 
distribution. A Weibull distribution, with scale factor s = 82.3, shape factor b = 1.36, and 
location factor l = 0, best fits the corrosion rate distribution for the crevice-area-only case. The 
cumulative distribution function of Ro for the crevice-area-only case is given in Figure 6-31. 
The measurement error for the crevice-area-only case was taken to be the same as the crevice 
sample case given in Table 6-6. Using the same mean value of the same temperaturedependence 
term (C1) (i.e., ) 47 . 296 , 47 . 116 , 3 ( K K N = - = s  ) and sampling for Ro from the 
entire corrosion rate distribution for the conservative crevice-area-only case (Figure 6-31), the 
general corrosion rate distributions were calculated at 25C, 50C, 75C, 100C, 125C, and 
150C using the temperature-dependent model in Equation 6-28. The results are shown in 
Figure 6-32. For the C1 value sampled at the mean, the CDFs in the figure represent the range of 
the variable general corrosion rates of the WPOB at each exposure temperature of interest for the 
conservative crevice-area-only case. Because it is not known what caused the higher corrosion 
rates for the crevice samples, the alternative conservative interpretation of the Alloy 22 general 
corrosion rate is not included in the waste package degradation analysis. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-51 October 2004 
Boldly Exposed (Non-crevice) Area 
Crevice 
Area 
NOTE: Diameter of the crevice former (washer) is 0.75 inches (19.05 mm). 
Figure 6-29. Schematic Showing the Boldly Exposed Area and the Crevice Area Under the Crevice 
Former of the Crevice Sample 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-30. Empirical CDFs for General Corrosion Rates of Crevice-Area Only, Crevice Samples, and 
Weight-Loss Samples After 5-Year Exposure in the LTCTF 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-52 October 2004 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-31. Cumulative Distribution Function (CDF) of Ro of the Crevice-Area-Only Case Temperature- 
Dependent General Corrosion Model of the Waste Package Outer Barrier 
Output DTN: MO0409MWDUGCMW.000. 
NOTE: The calculation was performed using the mean value (-3116.47 K) of the temperature-dependence term 
(C1), and the calculated general corrosion rate range represents the variability of the rate. 
Figure 6-32. Calculated Model Outputs of the Temperature-Dependent General Corrosion Model Based 
on the Crevice-Area-Only Case at Temperatures of 25C, 50C, 75C, 100C, 125C, and 
150C 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-53 October 2004 
6.4.4 Localized Corrosion 
Localized corrosion is a phenomenon in which corrosion progresses at discrete sites or in a 
nonuniform manner. The rate of localized corrosion penetration is generally higher than the rate 
of general corrosion penetration. The analysis assumes that crevice corrosion is representative of 
localized corrosion of the WPOB under the exposure conditions expected in the postclosure 
repository (Assumption 5.3). This is a conservative and bounding assumption because the 
initiation thresholds for crevice corrosion in terms of water chemistry and temperature are lower 
than those for pitting corrosion (Gdowski 1991 [DIRS 100859], Section 3.0; Haynes 
International 1997 [DIRS 100896]; Haynes International 1997 [DIRS 100897]), which is another 
form of localized corrosion. 
Localized corrosion of the WPOB is analyzed in this report with two model components: an 
initiation model and a propagation model. In the localized corrosion initiation model, localized 
corrosion of the WPOB occurs when the open-circuit potential, or corrosion potential (Ecorr), is 
equal to or greater than a critical threshold potential (Ecritical), that is, .E (= Ecritical - Ecorr) = 0. 
The magnitude of .E is an index of the localized corrosion resistance; that is, the larger the 
difference, the greater the localized corrosion resistance. This conceptual model of localized 
corrosion initiation is widely accepted by the corrosion community and has been published 
extensively (Bhni 2000 [DIRS 164137], Section B; Dunn et al. 2000 [DIRS 164495]; Dunn et 
al. 2003 [DIRS 164138]; Frankel 1998 [DIRS 162216]; Frankel 2002 [DIRS 164140]; Frankel 
and Kelly 2002 [DIRS 164141]; and Beavers et al. 2002 [DIRS 158781], Section 8.3). The 
localized corrosion initiation model components (i.e., Ecorr and Ecritical) could be affected by the 
sample configuration (crevice, disk or rod), metallurgical condition (mill annealed or as-welded), 
and exposure conditions (temperature, pH, chloride ion concentration, or nitrate ion 
concentration). 
A series of the electrochemical corrosion tests were conducted to generate the data for the 
localized corrosion initiation model. The typical sequence for electrochemical testing is 
summarized in Appendix I. As discussed in Section 6.4.4.4, a set of long-term open-circuit 
potential measurements was used to measure the long-term corrosion potentials (Ecorr) of 
Alloy 22 in a wide range of exposure environments. A series of cyclic potentiodynamic 
polarization (CPP) tests were also performed to measure the critical potentials (Ecritical) of 
Alloy 22 for differing sample configurations and metallurgical conditions in a wide range of 
exposure environments. 
Crevice corrosion initiation and propagation can be affected by the initial condition of the 
specimen surface prior to testing. Handbook data (Kain 1987 [DIRS 155193], p. 306) shows, for 
a variety of alloys, that fewer crevices initiate on as-received (mill condition) specimens than on 
specimens that have been wet ground to a 120-grit surface finish. This behavior results from the 
ability to form a tighter crevice on ground surfaces promoting breakdown of the passive film 
(Kain 1987 [DIRS 155193], p. 303). In this report, as discussed in Appendix I, the samples used 
for analysis of crevice corrosion initiation had an equivalent 600-grit surface finish. If the 
as-emplaced waste packages have a rougher surface finish, the localized corrosion initiation 
model developed in this report will be conservative relative to the expected behavior of the waste 
packages in the repository. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-54 October 2004 
In this report, localized corrosion of the WPOB is assumed to propagate at a (time-independent) 
constant rate (Assumption 5.4). This assumption is conservative because it is known that the 
localized corrosion rate decreases with time (Hunkeler and Boehni 1983 [DIRS 162221]; 
McGuire et al. 1998 [DIRS 152193], Section 5.2.8). Section 6.4.4.7 provides additional 
discussion on this issue. 
6.4.4.1 Overview of Approaches for Selection of Critical Potential for Localized 
Corrosion Initiation 
Localized corrosion of the WPOB occurs when the long-term corrosion potential (Ecorr) is equal 
to or greater than a certain critical potential (Ecritical), that is, .E (= Ecritical - Ecorr) = 0. Ecorr and 
Ecritical could be affected by the sample configuration (crevice, disk, or rod), metallurgical 
condition (mill annealed, as-welded, or as-welded plus thermally aged), and exposure condition 
(temperature, pH, chloride ion concentration, or nitrate ion concentration). 
Ecritical can be defined as a potential above which the current density or corrosion rate of Alloy 22 
increases significantly and irreversibly above the general corrosion rate of the passive metal 
(ASTM G 61-86 1987 [DIRS 127897]; Jones 1992 [DIRS 169906], Chapter 7). Above this 
potential local breakdown of the passive film can occur. The value of Ecritical cannot be measured 
as easily as the value of Ecorr because the value of Ecritical is also affected by the method used for 
its measurement. 
The true value of Ecritical of a metal or alloy for a given set of conditions (including sample 
configuration, metallurgical condition, and exposure condition) would be the lowest potential at 
which the corrosion current (except for initial transients) does not decay with time and is 
significantly higher than the passive current density, when held potentiostatically. Therefore, 
one approach to defining Ecritical is to conduct a series of potentiostatic polarization (PSP) tests at 
predetermined potentials near the critical potentials initially measured by shorter-term cyclic 
potentiodynamic polarization (CPP) tests. CPP tests themselves have been widely used to obtain 
the critical potential (Jain et al. 2003 [DIRS 164087]; Dunn and Brossia 2002 [DIRS 162213]; 
Brossia et al. 2001 [DIRS 159836]) likely due to the much shorter test times required than for 
PSP tests. CPP tests were used in this report to determine the critical potential for the Alloy 22 
WPOB. 
In using the CPP technique to identify critical parameters for the initiation of localized corrosion, 
the potentialcurrent curves are examined to look for values of the potential where there was a 
discernible, often abrupt, change of the current, much like a point of inflection on the potential 
current curve. The advantage of this approach is that the current change can be related to 
physical/chemical events occurring on the metal surface over the course of the polarization cycle. 
Because the potential is scanned initially in the oxidizing or anodic direction, and then in the 
reducing or cathodic direction, hysteresis of the curve is indicative of changes that have occurred 
on the metal surface during polarization, and the amount of this hysteresis is related to localized 
corrosion susceptibility (Jones 1992 [DIRS 169906], Chapter 7). Figure 6-33 shows a schematic 
of CPP curves showing different polarization behaviors for an alloy with a high resistance to 
localized corrosion. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-55 October 2004 
Figure 6-33. Schematic Potentiodynamic Polarization Curve Showing Likely Differing Behaviors of the 
Curves During Potentiodynamic Scanning of an Alloy with High Resistance to Localized 
Corrosion 
To produce curves such as those shown in Figure 6-33, the electrochemical potential is 
continuously scanned from slightly below the open-circuit or corrosion potential following a 
relatively short period of exposure of the metal specimen to the environment. If the metal is 
passive (as in the case of Alloy 22), the anodic current tends to have a low and nearly constant 
value for a wide range of potential; but eventually a potential is reached where there is a sharp 
increase in current. This change may be the beginning of oxygen evolution from water (if the 
applied potential is sufficient to electrolyze water). If this potential corresponds to oxygen 
evolution, passive film breakdown or localized corrosion would not initiate. On the other hand, 
this change in current may indicate the breakdown of the passive film, which could result from a 
number of electrochemical reactions. 
After the potential scan is reversed, in cases where film breakdown due to localized corrosion 
has occurred, the metal surface is altered from its initial state (the passive film has broken down 
in some places), and the current shows, on reverse scan, a positive hysteresis. That is, 
compared to the forward scan, the current at a given potential is higher on the reverse scan. 
However, eventually the reverse-scan curve crosses over the curve generated during the forward 
scan. Where the reverse scan intersects the forward scan, repassivation is considered complete 
(the passive film has been repaired). The potential at the intersection is called the repassivation 
potential in this report (e.g., the pit repassivation potential (Erp) for a boldly exposed sample or 
the crevice repassivation potential (Ercrev) for a creviced sample geometry). 
In some cases there is no hysteresis or only slightly positive or slightly negative hysteresis, 
meaning the reactions are reversible, and the current retraces the values from the forward scan, 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-56 October 2004 
often crossing the forward scan more than once at potentials above the passive region. In some 
cases, a slightly positive hysteresis is observed with no traces of localized corrosion on the 
specimen surface and in other cases, crevice corrosion may be observed on a specimen that 
produced no hysteresis. The current on the reverse scan usually falls through zero, as it does at 
Ecorr during the increasing polarization. Almost always, this new apparent corrosion potential at 
the zero current is much more positive than the initial corrosion potential. If oxygen evolution 
has occurred, the solution has higher oxygen content and this would make the new corrosion 
potential more noble. If some additional oxidation of the alloy has occurred, this would also 
make the corrosion potential more noble on the reverse scan. If transpassive dissolution 
occurred, the reverse scan does not cross the forward scan; it traces down the forward scan. In 
the transpassive region, the entire metal surface has been depassivated (the passive film is 
absent). In these cases, the passive film has broken down, but not only in localized areas, so 
active general corrosion occurs. As the potential is scanned further in the reverse direction, this 
base material becomes passivated (a new passive film forms). 
Many cyclic polarization curves obtained in concentrated solutions at elevated temperatures do 
not exhibit the same shapes as those observed in ideal curves, such as those illustrated in 
ASTM G 61-86 (1987 [DIRS 127897]) (i.e., Stainless Steel Type 304 and nickel-base 
Alloy C-276 in 3.5 percent NaCl at room temperature). In some of the solutions, polarization 
curves of Alloy 22 did not show a well-defined passive region. These observations may indicate 
that the alloy is undergoing general corrosion, not localized corrosion. 
Another complicating factor observed in many of the polarization curves was the appearance of 
one or more humps in the passive region of the forward scan. These are due to changes in 
oxidation state of one or more of the metallic components in the passive film, and in some cases 
indicate changes in the morphology and structure of the film, with possible implications on 
localized corrosion susceptibility. Usually, humps were not observed during the reverse scan. 
For some test conditions in which no hump was present in the forward scan, humps were 
observed in the reverse scan. 
There is no agreement among researchers about the definition of the repassivation potential 
(Erp or Ercrev for creviced specimens) in CPP tests. Many researchers identify the repassivation 
potential as the potential at which the reverse scan intersects the passive region of the forward 
scan (or the potential at which the forward current density equals reverse current density). 
A critical potential is not measured for the conditions where there is no positive hysteresis, 
because no localized corrosion has occurred. However, for conditions where the passive region 
in the forward scan is not clearly defined, the reverse scan never intersects the forward scan or 
the reverse scan crosses the forward scan more than once. In such cases, the repassivation 
potential can be subject to the judgment of an individual investigator and could result in 
inconsistent selection of the repassivation potential value. 
The above approach has been shown to produce overly conservative repassivation potential 
values for Stainless Steel Type 304 materials in chloride solutions (Akashi et al. 1998 
[DIRS 163903]). In other studies using the Tsujikawa method (Akashi et al. 1998 
[DIRS 163903]) and its variation, the potential-step technique (Jain et al. 2003 [DIRS 164087]), 
which generally results in more reasonable values for the crevice repassivation potential than the 
CPP technique, Gruss et al. (1998 [DIRS 100893]) used a current-density threshold of 1 A/cm2 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-57 October 2004 
in selecting the crevice repassivation potential. Other investigations have used a current-density 
threshold of 2 A/cm2 to define the crevice repassivation potential (Jain et al. 2003 
[DIRS 164087]; Dunn and Brossia 2002 [DIRS 162213]; Brossia et al. 2001 [DIRS 159836]). 
However, comparison of the repassivation potentials of Alloy 22 obtained with different test 
methods has shown that, when an appropriate criteria was employed in selecting the critical 
potential value, the repassivation potential obtained with the CPP method was similar to the 
repassivation potential obtained with the more time-consuming PSP method, the Tsujikawa 
method, or other similar methods (Jain et al. 2003 [DIRS 164087]). 
Another study of Alloy 22 crevice corrosion behavior utilized the CPP technique and specimens 
containing multiple crevice assemblies (MCA) (Kehler et al. 1999 [DIRS 162230]; Scully et al. 
1999 [DIRS 110246]; Kehler et al. 2001 [DIRS 162231]). In this study, the potential at which 
the current density permanently exceeded 1 A/cm2 in the forward scan was selected as a 
threshold potential to define crevice corrosion initiation (or crevice stabilization). In this section, 
this potential is referred to as Ef1. The study also used two current-density thresholds in the 
reverse scan to define crevice repassivation potentials, 10 A/cm2 and 1 A/cm2. In this section, 
these potentials are referred to as Er10 and Er1, respectively (Kehler et al. 1999 [DIRS 162230]; 
Scully et al. 1999 [DIRS 110246], Section 1.3; Kehler et al. 2001 [DIRS 162231]). It was shown 
that the crevice repassivation potentials were more stable and reproducible than the observed 
corrosion potentials. In many instances, the crevice corrosion initiation potential was associated 
with the transpassive dissolution and not with actual crevice corrosion initiation. The crevice 
repassivation potential defined at 1 A/cm2 was more likely to be associated with deactivation of 
crevice corrosion that resulted from net cathodic electrochemical reactions in the crevice, and not 
necessarily associated with crevice repassivation. The crevice repassivation potential defined at 
10 A/cm2 obtained at slow scan rate was found to be more representative of crevice 
repassivation (Kehler et al. 1999 [DIRS 162230]; Kehler et al. 2001 [DIRS 162231]). 
In most CPP scans of highly corrosion-resistant alloys, the passive current is on the order of 1 to 
10 A/cm. The passive current density on the reverse scan is usually greater than in the initial 
(or forward) scan. This is because the newly formed (during the reverse scan) oxides over the 
crevice site are thin, defective, and can support charge transmission at higher rates than the 
typically thicker and less-defective oxides present during the forward scan. Moreover, the 
solution inside the crevice is acidified from hydrolysis of cations released into the crevice 
solution during the forward scan (Kehler et al. 1999 [DIRS 162230]; Kehler et al. 2001 
[DIRS 162231]). 
After review of the different approaches to obtaining the critical potential for localized corrosion 
initiation, the repassivation potential obtained from CPP tests was chosen as the basis for 
localized corrosion initiation analysis in this report. As discussed previously, in some cases the 
reverse scans showed slightly positive or slightly negative or no hysteresis at all, often crossing 
the forward scan more than once at potentials above the passive region, that is, at potentials in 
the highest section of the anodic polarization curves. In these latter cases, evidence of localized 
corrosion was observed in some instances and not in others. A highly conservative approach 
would be not to use these data in development of the model. This would be extremely 
conservative because environments in which localized corrosion was not observed (even under 
high anodic polarization) would not contribute to the model predictions. Also, environments in 
which localized corrosion was sometimes observed (e.g., in only 5 percent of tested specimens) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-58 October 2004 
would be reflected in the model as environments in which localized corrosion always occurred. 
At the same time, given the importance of localized corrosion to waste package performance, 
some conservatism is warranted. For the modeling purposes, in cases where the 
nitrate-to-chloride ion ratio of the testing solution was 0.50, a crevice repassivation potential of 
+600 mV SSC was used. In the cases where the nitrate-to-chloride ion ratio was less than 0.50, 
the data from tests that did not produce a repassivation potential were not used. That is, for 
nitrate-to-chloride ratios of 0.50 and higher when a clear crossover on the passive region of 
potentials was not observed, the default repassivation potential was set to +600 mV SSC. For 
ratios of nitrate-to-chloride lower than 0.50, when a clear cross over in the passive region was 
not observed, the repassivation potential data were not used. This last approach adds 
conservatism to the model predictions. 
The value of +600 mV SSC was selected since repassivation potentials higher than +600 mV 
SSC may not have physical meaning. At potentials of +600 mV SSC or higher, the apparent 
breakdown of passivity of Alloy 22 may actually be oxygen evolution from water and/or 
transpassive dissolution processes. The values of potential for oxygen evolution and transpassive 
dissolution depend on the pH of the solution and the temperature. Above about +600 mV SSC, 
Cr3+ is not stable in the protective Cr2O3 oxide film formed on Alloy 22 and further oxidizes to 
Cr6+. For example, the Pourbaix diagram for pure chromium shows that at a pH of 7 and at 
ambient temperature (25C), the thermodynamically stable species would be Cr6+ at potentials 
higher than about +600 mV SHE (Pourbaix 1974 [DIRS 100817], p. 264). At 25C the Ag/AgCl 
reference electrode in saturated KCl solution is more noble than the standard hydrogen electrode 
scale by 199 mV (Sawyer and Roberts 1974 [DIRS 162259], pp. 39 to 45, Table 2-4); therefore, 
+600 mV SHE is about +400 mV SSC. The synergistic effects of other elements in Alloy 22 
such as nickel (Pourbaix 1974 [DIRS 100817], p. 333) and tungsten (Pourbaix 1974 
[DIRS 100817], p. 282) tend to raise the potential stability range (i.e., the transpassive potential) 
for the passive film formed on Alloy 22. For example, the transpassive potential for Alloy 22 in 
SAW solution at 90C has been reported to be about +620 mV SSC (Chen et al. 2002 
[DIRS 165441], Figure 10). Other investigators have reported similar Alloy 22 transpassive 
(or oxygen evolution or both) potentials (between about +860 and +980 mV SHE or about 
660 and 780 mV SSC) in various acidic (pH 3) chloride-containing solutions (Jayaweera et. al 
2003 [DIRS 162225], Section 9.2.2). Also, CPP tests in which it was determined that localized 
corrosion did occur always had repassivation potentials below +600 mV SSC (Appendices V, 
VI, VII, and VIII). The above analysis indicates that crossover potentials above approximately 
+600 mV SSC are more likely transpassive dissolution or oxygen evolution potentials and not 
true repassivation potentials. At high anodic potentials, surface modification of the tested 
specimens due to transpassive dissolution occurs; therefore, little hysteresis in the reverse scan is 
unavoidable. Therefore, it is reasonable to assign a repassivation potential value of +600 mV 
SSC to samples that did not undergo localized corrosion during the CPP tests as a method to 
account for the fact that localized corrosion of Alloy 22 is not observed in some experiments. 
Conservatively, only samples in exposure environments in which the nitrate-to-chloride ratio was 
0.50 were assigned this effective repassivation potential (i.e., credit was not taken for every 
sample that did not display localized corrosion, for example, in solutions with a nitrate-tochloride 
ion ratio less than 0.50). This approach is conservative and defensible for the prediction 
of long-term localized corrosion susceptibility of the WPOB in the repository. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-59 October 2004 
As discussed in the following section, with few exceptions, the repassivation potentials of 
crevice samples (i.e., measurements of the crevice repassivation potential, Ercrev) were used for 
localized corrosion initiation analysis. Investigators at the Center for Nuclear Waste Regulatory 
Analyses (CNWRA) used the same approach (also using crevice samples) (Brossia et al. 2001 
[DIRS 159836], Table A-1). 
6.4.4.2 Cyclic Potentiodynamic Polarization Data Analysis for Crevice Repassivation 
Potential 
A series of cyclic potentiodynamic polarization (CPP) tests were performed for Alloy 22 samples 
over a wide range of exposure environments. Included in the tests were a variety of electrolyte 
solution chemistries, exposure temperatures, sample geometries and configurations (i.e., multiple 
crevice assembly (MCA), rod, and disc), and metallurgical conditions (i.e., mill annealed, 
as-welded, and as-welded plus thermally aged). 
The CPP tests included simple salt solutions such as NaCl, CaCl2, and mixed CaCl2 and 
Ca(NO3)2 solutions and mixed NaCl and KNO3 solutions. A wide range of concentrations up to 
near saturation were used. Descriptions of the electrochemical corrosion test procedures used to 
generate data for this report are provided in Appendix I. The CPP measurements were based on 
ASTM G 5-94 1994 [DIRS 117479]). Necessary deviations from the standard have been noted in 
the scientific notebooks corresponding to the DTNs used. Analyses of the CPP test data were 
performed to obtain repassivation potentials. Initial data screening and analysis are documented 
in DTNs: LL030409512251.051 [DIRS 163462] and LL040402212251.084 [DIRS 170097]. 
The repassivation potential data reported in these DTNs was supplemented as discussed below. 
As discussed in Section 6.3 contact points between the waste package and structural components 
in the drift as well as with mineral deposits formed by evaporative concentration of solutions 
contacting the waste package could form crevices on the waste package surface. Therefore, only 
the crevice (MCA) sample data were considered for the repassivation potential model analysis 
with the exception of the repassivation potential data for samples DEA598, DEA599, and 
DEA600 (DTN: LL030409812251.054 [DIRS 164185]), which were disc samples exposed to 
high chloride concentrations (12.6 to 20.8 m) and high temperatures (120C and 130C). In the 
case of noncreviced samples, only a repassivation potential (Erp) is obtained, but in this report, 
the repassivation potential is treated in the same way as the crevice repassivation potential 
(Ercrev). The repassivation potential data were included in the data used to build the models 
because relatively few MCA data points exist at these high temperatures and solution 
concentrations. Use of these data improves the predictive capability of the models. Although 
MCA and disc samples have different geometries, and may be subject to slightly different local 
passive film breakdown mechanisms, there were no significant differences in the repassivation 
potential between the two types of samples at high temperatures and ion concentrations. Also, 
two CPP test data for MCA samples (DEA3125 and DEA3127 from 
DTN: LL030409812251.054 [DIRS 164185]) exposed to high chloride (19.2 and 20.8 m) and 
high-temperature (130C) conditions with and without nitrate ions were also used in the model 
development. 
These additional data (disc samples DEA598, DEA599, and DEA600; MCA samples DEA3125 
and DEA3127) were analyzed following the same process as that used for the data in 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-60 October 2004 
DTN: LL030409512251.051 [DIRS 163462]. The analyses to obtain the crevice repassivation 
potentials (Ercrev) or repassivation potentials (Erp) of the above samples are illustrated graphically 
in Figure 6-34 to Figure 6-38. The resulting crevice repassivation potentials are shown in Table 
6-7. 
For the salt solutions in Table 6-7, the chloride and nitrate salts were considered to be completely 
dissociated. This approach is considered conservative as only a fraction of the ions are expected 
to be available to interact with the Alloy 22 surface due to strong interionic attractions in 
concentrated solutions. As noted in Table 6-7 and Appendix VI, the room temperature pH of the 
high chloride and high temperature solutions from DTN: LL030409812251.054 [DIRS 164185] 
was not reported. A measured room temperature pH of 4.14 for 5 M CaCl2 solutions tested 
at 120C (from the scientific notebook associated with DTN: LL030400112251.043 
[DIRS 163466] (i.e., Ilevbare 2003 [DIRS 171329], p. 141)) was used for 7 M CaCl2 solutions 
tested at 130C (samples DEA3125 and DEA599). Also, as noted in Table 6-7 and 
Appendix VIII, a measured room temperature pH of 5.34 for 5 M CaCl2 plus 0.05 M Ca(NO3)2 
solution at 120C from DTN: LL030502212251.063 [DIRS 163456] (e.g., samples JE 0024 and 
JE 0025 in MCA E-chem Data Submittal Sheet 4-29-03-King.xls) was used for the CaCl2 plus 
Ca(NO3)2 salt solutions (Samples DEA3127, DEA598 and DEA600). Because pH has a small 
effect on the crevice repassivation potentials relative to temperature and chloride concentration 
(Section 6.4.4.3), the impact of the substituted pH values for the high chloride and high 
temperature solutions will be minor. 
Source: DTN: LL030409812251.054 [DIRS 164185]; CP_DEA3125.xls. 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-34. Determination of Crevice Repassivation Potential of Mill-Annealed MCA Sample 
(Sample DEA 3125) Tested in 7 M CaCl2 Solution at 130C 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-61 October 2004 
Source: DTN: LL030409812251.054 [DIRS 164185]; CP_DEA3127.xls. 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-35. Determination of Crevice Repassivation Potential of Mill-Annealed MCA Sample 
(Sample DEA 3127) Tested in 7 M CaCl2 + 0.7 M Ca(NO3)2 Solution at 130C 
Source: DTN: LL030409812251.054 [DIRS 164185]; CP_DEA598.xls. 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-36. Determination of Repassivation Potential of Mill-Annealed Disc Sample (Sample DEA 598) 
Tested in 6 M CaCl2 + 0.6 M Ca(NO3)2 Solution at 120C 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-62 October 2004 
Source: DTN: LL030409812251.054 [DIRS 164185]; CP_DEA599.xls. 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-37. Determination of Repassivation Potential of Mill-Annealed Disc Sample (Sample DEA 599) 
Tested in 7 M CaCl2 Solution at 130C 
Source: DTN: LL030409812251.054 [DIRS 164185]; CP_DEA600.xls. 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-38. Determination of Repassivation Potential of Mill-Annealed Disc Sample (Sample DEA 600) 
Tested in 7 M CaCl2 + 0.7 M Ca(NO3)2 Solution at 130C 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-63 October 2004 
Table 6-7. Crevice Repassivation Potentials Obtained from the Additional CPP Data 
Specimen 
ID 
Sample 
Type a) 
Metallurgical 
Condition a) Electrolyte d) Temp. 
(C) pH b) 
[Cl] 
(moles/kg 
water) c) 
[NO3] 
(moles/kg 
water) c) 
Ercrev 
(mV SSC) e) 
DEA598 Disc MA 6 M CaCl2 + 0.6 M Ca(NO3)2 120 5.34 16.323 1.640 37 
DEA3125 MCA MA 7 M CaCl2 130 4.14 19.228 0.000 -197 
DEA599 Disc MA 7 M CaCl2 130 4.14 19.228 0.000 -229 
DEA3127 MCA MA 7 M CaCl2 + 0.7 M Ca(NO3)2 130 5.34 20.815 2.073 32 
DEA600 Disc MA 7 M CaCl2 + 0.7 M Ca(NO3)2 130 5.34 20.815 2.073 24 
Source: DTN: LL030409812251.054 [DIRS 164185]. 
NOTES: a MCA = multiple crevice assembly, Disc = disc sample, MA = mill annealed, SSC = silver-silver chloride reference 
electrode. 
b A measured room temperature pH of 4.14 for 5 M CaCl2 solutions tested at 120C (from the scientific notebook 
associated with DTN: LL030400112251.043 [DIRS 163466] (i.e., Ilevbare 2003 [DIRS 171329], p. 141)) was used for 7 
M CaCl2 solutions tested at 130C (Samples DEA3125 and DEA599). Also a measured room temperature pH of 5.34 for 
5 M CaCl2 plus 0.05 M Ca(NO3)2 solution tested at 120C from DTN: LL030502212251.063 [DIRS 163456] was used for 
CaCl2 plus Ca(NO3)2 salt solutions (Samples DEA3127, DEA598, and DEA600). All pH values were measured at room 
temperature. 
c Molal concentrations of chloride and nitrate ions of test solutions are from DTN: LL030703723121.031 [DIRS 164184]. 
d All solutions were considered to be fully dissociated. 
e The Ercrev values were obtained from the individual CPP curves plotted in Figures 6-33 through 6-37 following the same 
process as that used for the data in DTN: LL030409512251.051 [DIRS 163462]. 
As discussed in DTN: LL030409512251.051 [DIRS 163462], samples that showed abnormal 
polarization behavior (due to contamination or damage, or both during the sample fabrication 
process) were excluded from the analysis. In addition, Sample DEA3122 was excluded because 
the molal concentrations for chloride and nitrate ions and pH of the test solution used (9 M CaCl2 
plus 0.9 M Ca(NO3)2 solution at 170C) were not available. 
Also, data in DTNs: LL030409512251.051 [DIRS 163462] and LL030409812251.054 
[DIRS 164185], which did not show the occurrence of localized corrosion (i.e., any 
repassivation potential reported would not represent actual repassivation of a sample 
undergoing localized corrosion), were not included in the model development. This is 
conservative since environments in which localized corrosion was not observed (even under 
polarization) will not contribute to the model results. One should note that some data in 
DTN: LL040402212251.084 [DIRS 170097] (discussed below) in which the nitrate-to-chloride 
ratio in the test solution was equal to 0.50 and localized corrosion may not have occurred under 
polarization, were used in model development. No data that did not show abnormal polarization 
behavior (due to contamination and/or damage during the sample fabrication process) in 
DTNs: LL030409512251.051 [DIRS 163462] and LL030409812251.054 [DIRS 164185] were 
obtained at nitrate-to-chloride ratios above 0.50. 
DTN: LL040402212251.084 [DIRS 170097] contains a data set of crevice repassivation 
potential measurements from as-welded MCA samples exposed to mixed NaCl and KNO3 
solutions and mixed CaCl2 and Ca(NO3)2 solutions (as well as some others as discussed below). 
The pH of the high chloride and high temperature solutions was not reported and a measured 
room temperature pH of 5.34 for a 5 M CaCl2 plus 0.05 M Ca(NO3)2 solution tested at 120C 
from DTN: LL030502212251.063 [DIRS 163456] was used for these CaCl2 plus Ca(NO3)2 salt 
solutions. The pH of these solutions was not reported because these solutions are not liquid at 
room temperature so the pH could not be measured. Also, several crevice repassivation 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-64 October 2004 
potentials were not reported either because localized corrosion was not observed or the reverse 
scan crossed the forward scan above the passive region. In the cases where the nitrate-to-chloride 
ion ratio was 0.50, a crevice repassivation potential of +600 mV SCC was used (samples 
JE3216, JE3207, JE3246, JE1772, JE3226, JE1775, JE3247, JE3285, JE3273, and JE3271). In 
the cases where the nitrate-to-chloride ion ratio was less than 0.50, the data was not used 
(samples JE1774, JE3249, and JE3265). 
Several data points were not used in the model development including mixed ion solutions of 
NaCl and NaHCO3 (samples JE3288 through JE3291 and JE3293 through JE3296), mixed ion 
solutions of NaCl, NaNO3, and MgSO4 (samples JE3258 through JE3263). These data were not 
used since only the effects of the nitrate ion are accounted for in the model. 
DTN: LL040402212251.084 [DIRS 170097] also contained a limited data set at nitrate-tochloride 
ion ratios in excess of 0.50 (samples JE3252 through JE3255, JE3297 through JE3300, 
and JE3292) with few pH or crevice repassivation potentials reported. These data were not used 
in development of the functional forms used for evaluation of localized corrosion initiation 
between 20C and 120C (Section 6.4.4.3) due the small number of points and the lack of pH 
and crevice repassivation potential values. These data were used for corroboration in the 
evaluation of localized corrosion initiation at temperatures between 120C and 160C 
(Section 6.4.4.6.6). 
Since the majority of the data were obtained from MCA samples, the critical potential model 
developed in this report would be more accurately referred to as a crevice repassivation potential 
model. The crevice repassivation potential data, including those additional data from 
DTN: LL030409812251.054 [DIRS 164185], that were considered for the critical potential 
model analysis are summarized in Appendix VI for those solutions not containing nitrate ions 
and Appendix VIII for those solutions containing nitrate ions. The appendices also provide the 
test conditions including sample geometry/configuration, metallurgical condition, test 
temperature, and electrolyte composition. For all the data in the appendices, chloride and nitrate 
salts were considered to be completely dissociated. This approach is considered conservative as 
only a fraction of the ions are expected to be available to interact with the Alloy 22 surface due 
to strong interionic attractions in concentrated solutions. 
Investigators at the CNWRA used a similar approach to obtain the crevice repassivation potential 
data for Alloy 22. The data were reported by Brossia et al. (2001 [DIRS 159836], Table A-1). 
The test environments for the reported data are 0.005 M to 4 M chloride concentration and 80C 
to 150C. The data set for mill-annealed and as-welded conditions was used in the critical 
potential model analysis. The data set is summarized in Appendix VII, along with the test 
conditions including sample geometry or configuration, metallurgical condition, test temperature, 
and electrolyte composition. For all the data in the appendix, chloride and nitrate salts were 
considered to be completely dissociated. 
6.4.4.3 Crevice Repassivation Potential Model for Waste Package Outer Barrier 
As described in Section 6.4.4.1, the WPOB is considered to be subject to localized corrosion 
when the corrosion potential (Ecorr) exceeds or is equal to the crevice repassivation potential 
(Ercrev), that is: 
rcrev corr E E = (Eq. 6-30) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-65 October 2004 
For the WPOB localized corrosion analysis in the postclosure repository environments, the 
crevice repassivation potential (Ercrev) is expressed as follows: 
- . + = 3 NO 
rcrev 
o
rcrev rcrev E E E (Eq. 6-31) 
where o
rcrev E is the crevice repassivation potential in the absence of inhibitive nitrate ions, and 
- . 3 NO 
rcrev E is the crevice repassivation potential change resulting from the inhibiting effect of nitrate 
ion in solution. 
Development of the crevice repassivation potential model for the WPOB was performed 
considering a set of multiple regression models as a function of the major exposure environment 
variables such as temperature, pH, chloride ion concentration and nitrate ion concentration. The 
molal concentration unit (moles solute per kg water) was employed for the chloride and nitrate 
ion concentrations in the model development. This was to ensure an internal consistency with 
the total system performance assessment (TSPA), which also employs the molal concentration 
unit for the dissolved species. An advantage of using the molal concentrations is that the base of 
the concentration unit (i.e., mass of solvent, in this case water) and, thus, the concentration value, 
does not change with temperature. 
The crevice repassivation potential data for Alloy 22 from the Project and CNWRA are listed in 
Appendices VI, VII, and VIII. The CNWRA data are from the data compilation reported by 
Brossia et al. (2001 [DIRS 159836], Table A-1). Because the crevice repassivation potential of 
both the mill-annealed (MA) and as-welded (ASW) Alloy 22 samples behaved similarly, the data 
for two metallurgical conditions were combined for the model development. A negligible effect 
of welding on the crevice repassivation potential was also observed by the CNWRA 
investigators (Brossia et al. 2001 [DIRS 159836], Section 3.2.2, Figure 3-19). The CNWRA 
data for the aged samples in the same data compilation table were not considered because of the 
high aging temperature (870C) employed for the sample preparation. The dominant secondary 
phase that forms at the above aging temperature, and is responsible for degradation of the 
corrosion resistance of the alloy, is the s phase, which is stable between 800C and 930C and 
forms rapidly (BSC 2004 [DIRS 169983], Section 6.6.1, Figures 76 and 77). The tetrahedrally 
closed-pack (TCP) phases more relevant to repository conditions are P and  phases, which are 
stable over a wider temperature range than the s phase (BSC 2004 [DIRS 169983], 
Section 6.6.1, Figures 76 and 77). However, their formation kinetics are extremely slow at the 
temperatures that the waste packages are expected to experience in the repository (BSC 2004 
[DIRS 169983], Section 8). 
6.4.4.3.1 Crevice Repassivation Potential Model in Absence of Inhibitive Nitrate Ions 
Among the functional forms that were considered, the following empirical functional form was 
considered to adequately describe the relationship between the crevice repassivation potential of 
the mill-annealed and as-welded Alloy 22 and the test environment parameters in the absence of 
inhibiting nitrate ions. 
]) log([ ]) log([ 4 3 2 1 
- -  + + + + = Cl T a Cl a pH a T a a E o 
o
rcrev (Eq. 6-32) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-66 October 2004 
where o
rcrev E is the crevice repassivation potential (mV SSC) in the absence of inhibiting nitrate 
ions, ao, a1, a2, a3, and a4 are constants, T is the temperature (C), and ] [ - Cl is the molal (m, 
moles/kg water) chloride ion concentration. 
The above functional form is similar to that for the crevice repassivation potential of Alloy 22 
proposed by Brossia et al. (2001 [DIRS 159836], Section 3.2.2). Dependence of the critical 
potential on a logarithmic form of chloride concentration and a linear form of temperature were 
also used to model the critical potential by other investigators (Brossia et al. 2001 
[DIRS 159836], Section 3.2.2; Frankel 1998 [DIRS 162216]; Frankel 2002 [DIRS 164140]; 
Kehler et al. 2001 [DIRS 162231]). The pH was not included in the functional forms from the 
above investigators because of a weak dependence of the critical potential on pH. Relatively 
narrow pH ranges of the data used by the investigators may have led to difficulties in quantifying 
the effect of pH. However, a reasonable pH range (pH 4.1 to 8, see Appendices VI and VII) of 
the database used in the current analysis allowed quantification of the pH effect. As will be 
discussed in Section 6.4.4.6, the crevice repassivation model shows a relatively weaker effect of 
pH relative to temperature and chloride concentration (Figure 6-61 and Figure 6-62). 
Using the method of least squares, the above functional form was fit to the crevice repassivation 
potential data for the mill-annealed and as-welded conditions in Appendices VI and VII. The 
model fitting was performed using Mathcad version 11.1, and the Mathcad worksheet for the 
model fitting is given in the output DTN: MO0409MWDULCMW.000. The value of the 
coefficients and their uncertainty (1 standard deviation) of the model parameters from the 
fitting were determined to be: = 0 a 214.089  46.880, = 1 a -3.696  0.476, = 2 a 25.284  5.641, 
= 3 a -252.181  53.912, and = 4 a 1.414  0.547. The covariance matrix resulting from the fitting 
procedure was determined to be: 
. . . . . . 
.
. 
. . . . . . 
.
. 
  -   -  
 -   -   - 
  -   -  - 
 -   -   - 
  -  -  -  
= 
- - - 
-
- - 
1 1 1 1 1 
1 3 1 1 3 
1 1 1 0 1 
1 1 0 1 1 
1 3 1 1 3 
10 995 . 2 10 868 . 2 10 425 . 7 10 996 . 1 10 590 . 1 
10 868 . 2 10 907 . 2 10 237 . 3 10 877 . 1 10 805 . 1 
10 425 . 7 10 237 . 3 10 183 . 3 10 240 . 1 10 325 . 8 
10 996 . 1 10 877 . 1 10 240 . 1 10 267 . 2 10 516 . 1 
10 590 . 1 10 805 . 1 10 325 . 8 10 516 . 1 10 198 . 2 
CV (Eq. 6-33) 
The correlation coefficient R for the fit is 0.872, and the coefficient of determination R is 0.760. 
R2 is the ratio of the measures of variation explained by the regression model to the total 
variation present in the output variable under consideration. Values of R vary between 0 (no 
variation explained and a very poor regression model) to 1 (perfect explanation of the model 
variation by the regression model). With the measure of a R2 value of 0.760, the regression 
model fits the experimental data reasonably well. 
Variation in the crevice repassivation potential data for a given test condition are mostly due to 
the uncertainties associated with the test procedures and crevice repassivation potential selection 
criteria, in addition to some randomness in the localized corrosion process. Therefore, the entire 
variance of the model is due to uncertainty. ASTM G 61-86 (1987 [DIRS 127897]) specifies, 
when the standard procedure for the CPP measurements is followed, an investigators data 
should fall within the range of 2 standard deviations of the mean because this includes 95 % of 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-67 October 2004 
all data provided random variations are the only source of error. While this criterion was 
specified for replicate CPP measurements obtained under the same exposure conditions, it is 
reasonable to apply this criterion to a model based on fitting these same measurements to a 
regression surface. Therefore, the uncertainty of the coefficients of the regression model is 
limited to 2 standard deviations. Also, the approach and criteria for obtaining the crevice 
repassivation potentials from the CPP curves are highly conservative; therefore, limiting the 
uncertainty of the model parameters to 2 standard deviations is sufficient to capture the model 
uncertainty. 
For the waste package degradation analysis, variability in the crevice repassivation potential 
among waste packages is represented by the temporally and spatially varying waste package 
temperature and water chemistry contacting the waste package. In addition, the chemistry of 
water contacting waste package may vary depending on the thermal and hydrologic condition on 
the waste package surface, for example, the presence or absence of dripping water. In the 
absence of dripping water, the chemistry of water film forming on the waste package surface 
would be determined by the interactions of the chemical constituents in the dust on the surface 
with the water vapor in the humid-air around the waste package. 
The model results and the Projects data are shown as a function of temperature and chloride 
concentration in Figure 6-39 and Figure 6-40 respectively. Note the model results are for the 
average values of the test environment parameters (temperature, chloride concentration and pH) 
of the source data. The Ercrev data for the test conditions off the average values, therefore, are not 
bound within 2 standard deviations of the model mean. 
As shown in Figure 6-39, the crevice repassivation potential is a strong function of temperature 
and a relativity weaker function of chloride concentration. This strong dependence of the crevice 
repassivation potential of Alloy 22 on temperature was also reported by others (Brossia et al. 
2001 [DIRS 159836], Section 3.2.2; Kehler et al. 2001 [DIRS 162231]). A logarithmic 
dependence of the crevice repassivation potential on chloride concentration (Figure 6-40) shows 
that the crevice repassivation potential decreases rapidly with chloride concentration for the low 
chloride concentration range, and the dependence becomes weaker as the chloride concentration 
increases. Although not shown here, it is seen from the value of the pH term coefficient that the 
crevice repassivation potential is a weak function of pH. 
The model results and the CNWRA data are shown as a function of temperature and chloride 
concentration in Figure 6-41 and Figure 6-42, respectively. As for the above discussion of the 
Projects data, the model results are for the average values of the test environment parameters 
(temperature, chloride concentration and pH) of the source data. The Ercrev data for the test 
conditions off the average values are, therefore, not within 2 standard deviations of the model 
mean. The behavior of the crevice repassivation potential data from CNWRA and their 
dependence on temperature and chloride concentration are consistent with Project data. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-68 October 2004 
LLNL Ercrev vs. Temp for Varying [Cl] with No Nitrate 
(Model Calculations for Avg. 10 m [Cl] and Avg. pH 4.6) 
-400 
-300 
-200 
-100
0 
100 
200 
40 60 80 100 120 140 160 180 
Temperature (C) 
Crevice Repassivation Potential 
(mV vs. SSC) 
1 m [Cl] 
1.3 m [Cl] 
2.6 m [Cl] 
5.4 m [Cl] 
12 m [Cl] 
19.2 m [Cl] 
Model Mean 
Mean -1 sd 
Mean + 1 sd 
Mean - 2 sd 
Mean + 2 sd 
Output DTN: MO0409MWDULCMW.000. 
NOTE: The model calculations are for the average values of chloride concentration (10 m) and pH (4.6) of the 
Projects crevice repassivation potential data used for the model development. 
Figure 6-39. Model Results and Projects Experimental Data for the Crevice Repassivation Potential of 
the Waste Package Outer Barrier in Absence of Inhibiting Nitrate Ion as a Function of 
Temperature 
Output DTN: MO0409MWDULCMW.000. 
NOTE: The model calculations are for the average values of temperature (88C) and pH (4.6) of the Projects 
crevice repassivation potential data used for the model development. 
Figure 6-40 Model Results and Projects Experimental Data for the Crevice Repassivation Potential of 
the Waste Package Outer Barrier in Absence of Inhibiting Nitrate Ion as a Function of 
Chloride Concentration 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-69 October 2004 
Output DTN: MO0409MWDULCMW.000. 
NOTE: The model calculations are for the average values of chloride concentration (2.1 m) and pH (7.8) of the 
CNWRAs crevice repassivation potential data used for the model development. 
Figure 6-41. Model Results and CNWRAs Experimental Data for the Crevice Repassivation Potential of 
the Waste Package Outer Barrier in Absence of Inhibiting Nitrate Ion as a Function of 
Temperature 
CNWRA Ercrev vs. [Cl-] for Varying Temperatures with No Nitrate 
(Model Calculations for Avg. 113 C and Avg. pH 7.8) 
-200 
-100
0 
100 
200 
300 
400
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 
Chloride Concentration (m, moles/kg water) 
Crevice Repassivation Potential (mV SSC) 
80 C 
95 C 
105 C 
125 C 
150 C 
Model Mean 
Mean - 1 sd 
Mean + 1 sd 
Mean - 2 sd 
Mean + 2 sd 
Output DTN: MO0409MWDULCMW.000. 
NOTE: The model calculations are for the average values of temperature (113C) and pH (7.8) of the CNWRAs 
crevice repassivation potential data used for the model development. 
Figure 6-42. Model Results and CNWRAs Experimental Data for the Crevice Repassivation Potential of 
the Waste Package Outer Barrier in Absence of Inhibiting Nitrate Ion as a Function of 
Chloride Concentration 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-70 October 2004 
6.4.4.3.2 Crevice Repassivation Potential Changes in Presence of Inhibitive Nitrate Ions 
The crevice repassivation potential data in Appendix VIII show that nitrate ions generally raise 
the crevice repassivation potential, decreasing the possibility of localized corrosion initiation. In 
this report, the effect of nitrate ions on the crevice repassivation potential is represented with an 
adjustment factor ( - . 3 NO 
rcrev E ) to the crevice repassivation potential in the absence of nitrate ions 
( o 
rcrev E ). That is, - . 3 NO 
rcrev E is defined as the difference between the crevice repassivation potential 
with and without nitrate ions at the same chloride concentration and temperature. As can be seen 
in Appendix VIII, - . 3 NO 
rcrev E is obtained by first determining the crevice repassivation potential in a 
solution with a given chloride concentration and at a given temperature in the absence of nitrate 
ions (here taken to be the median value of o 
rcrev E ), then subtracting this value from the crevice 
repassivation potential determined in a solution with the same chloride concentration and at the 
temperature in the presence of nitrate ions. As can be seen from Appendix VIII, nitrate ions 
generally raise the crevice repassivation potential by a significant amount. 
The following functional form was found to adequately describe the effect of nitrate ions on the 
crevice repassivation potential. 
] [ 
] [ ] [ 3 
2 3 1 
3 
-
- 
- + + = . - 
Cl 
NO b NO b b E o 
NO 
rcrev (Eq. 6-34) 
where - . 3 NO 
rcrev E is the change of the crevice repassivation potential due to the inhibiting effect 
nitrate ions, ] [ - Cl is the molal (moles/kg water) concentration of chloride ions, ] [ 3
- NO is the 
molal concentration of nitrate ions, and bo, b1, and b2 are the model coefficients. Using the 
method of least squares, the above functional form was fit to the - . 3 NO 
rcrev E data in Appendix VIII. 
The model coefficient fitting was performed using Mathcad version 11.1 (the Mathcad 
worksheet is provided in the output DTN: MO0409MWDULCMW.000). 
The model coefficients and their uncertainty (1 standard deviation) resulting from the fitting 
procedure were determined to be: bo = 22.589  24.113, b1 = 33.748  5.180, and b2 = 749.745  
95.491. The covariance matrix resulting from the fitting procedure was determined to be: 
. . . 
.
. 
. . . 
.
. 
  -  - 
 -   - 
 -  -  
= 
3 2 3 
2 1 0 
3 0 2 
10 119 . 9 10 291 . 2 10 542 . 1 
10 291 . 2 10 683 . 2 10 737 . 1 
10 542 . 1 10 737 . 1 10 814 . 5 
CV (Eq. 6-35) 
The correlation coefficient R for the fit is 0.842, and the coefficient of determination R is 0.709. 
With the measure of a R2 value of 0.709, the regression model fits the experimental data fairly 
well. 
In the above model, the competing effect of the chloride and nitrate ions on the crevice 
repassivation potential is represented with the ratio of the ion concentrations (nitrate-to-chloride 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-71 October 2004 
ion ratio). The model uses a linear relationship between - . 3 NO 
rcrev E and the nitrate-to-chloride ion 
ratio. Because the effect of the measurement uncertainty of the CPP tests has already been 
captured in the crevice repassivation potential model in the absence of nitrate ions, the median 
values of the - . 3 NO 
rcrev E model coefficients are used to determine the crevice repassivation potential 
(Ercrev) (Equation 6-31). Because the maximum nitrate and chloride ion concentrations in the 
data used for construction of the model were 18 and 36 molal (m, moles per kg water), 
respectively, for ion concentrations above these values, these upper limits are imposed (i.e., if the 
exposure environment nitrate ion concentration is greater than 18 molal, the model is evaluated 
with a nitrate ion concentration of 18 molal. Similarly, because the maximum nitrate-to-chloride 
ion concentration ratio in the data used for construction of the model was 0.5, this upper limit is 
imposed (i.e., if the exposure nitrate-to-chloride ion concentration ratio exceeds 0.5, the 
value 0.5 is used in evaluating the model). Also, if only a negligible amount of nitrate ions are 
present (i.e., when the nitrate concentration is less than 0.001 m), the crevice repassivation 
potential is conservatively represented by o
rcrev E alone without use of - . 3 NO 
rcrev E . 
Variability in - . 3 NO 
rcrev E among waste packages is represented by the temporally and spatially 
varying nitrate and chloride ion concentrations of solutions contacting the waste package. The 
solution chemistry contacting the waste packages may vary due to variations in the thermal and 
hydrologic conditions on the waste package surface and due to the presence or absence of 
dripping water. 
Figure 6-43 shows the - . 3 NO 
rcrev E model results (at pH of 5.38) and the 6 m chloride ion 
concentration data at nitrate-to-chloride ion ratios of 0.05 (0.3 m nitrate ion concentration), 0.15 
(0.9 m nitrate ion concentration), and 0.50 (3 m nitrate ion concentration). Figure 6-44 shows the 
- . 3 NO 
rcrev E model results (at 27.1 m chloride ion and pH of 5.34) and the 20, 24, and 36 m chloride 
ion concentration data at nitrate-to-chloride ion ratios of 0.05 (1, 1.2, and 1.8 m nitrate ion 
concentrations, respectively for the 20, 24, and 36 m chloride ion solutions), 0.15 (3, 3.6, and 
5.4 m nitrate ion concentrations, respectively for the 20, 24, and 36 m chloride ion solutions), and 
0.50 (10, 12, and 18 m nitrate ion concentrations, respectively for the 20, 24, and 36 m chloride 
ion solutions). Note that the model results do not necessarily encompass the spread in the 
measured/calculated - . 3 NO 
rcrev E values. This may be due to the use of only the median values of 
o 
rcrev E during the development of the measured/calculated - . 3 NO 
rcrev E values. Nonetheless, the model 
is sufficient for its intended use (i.e., it provides an estimate of the beneficial effect of nitrate ions 
on the crevice repassivation potential). The curves in Figure 6-43 and Figure 6-44 change slope 
at 3 m nitrate ion and 13.55 m nitrate ion, respectively, because the nitrate-to-chloride ion ratio 
exceeds 0.50 at these concentrations and, as discussed above, the model is evaluated at a constant 
nitrate-to-chloride ion ratio of 0.50 under those conditions. This is a conservative approach to 
evaluating the repassivation potential because repassivation potentials increase with increasing 
nitrate concentration as shown in Figure 6-43 and Figure 6-44. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-72 October 2004 
Ercrev Changes (.Ercrev) vs. [NO3] 
(Model Calculations for 6 m [Cl], pH = 5.38) 
-200.00 
0.00 
200.00 
400.00 
600.00 
800.00 
1000.00
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 
Nitrate Concentration (m, moles/kg water) 
.Ercrev (mV vs. SSC) 
6m Cl Data 
Model Mean 
Mean - 1 sd 
Mean + 1 sd 
Mean - 2 sd 
Mean + 2 sd 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-43. Model Results and Projects Experimental Data for the Crevice Repassivation Potential 
Changes of the Waste Package Outer Barrier in Presence of Inhibiting Nitrate Ions at 6 m 
Chloride Ion Concentration and pH of 5.38 as a Function of Nitrate Ion Concentration 
Ercrev Changes (.Ercrev) vs. [NO3] 
(Model Calculations for 27.1 m [Cl], pH = 5.34) 
-300 
-100 
100 
300 
500 
700 
900 
1100 
1300 
1500 
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 
Nitrate Concentration (m, moles/kg water) 
.Ercrev (mV vs. SSC) 
20m Cl Data 
24m Cl Data 
36m Cl Data 
Model Mean 
Mean - 1 sd 
Mean + 1 sd 
Mean -2 sd 
Mean -2 sd 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-44. Model Results and Projects Experimental Data for the Crevice Repassivation Potential 
Changes of the Waste Package Outer Barrier in Presence of Inhibiting Nitrate Ions as a 
Function of Nitrate Ion Concentration (Model Results at 27.1 m Chloride Ion Concentration 
and pH of 5.34) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-73 October 2004 
6.4.4.4 Long-Term Open-Circuit Corrosion Potential Data Analysis 
Because the corrosion potential of Alloy 22 may change over time, it is important to know the 
most probable value of long-term corrosion potential (Ecorr) for Alloy 22 under different 
environmental conditions to evaluate the localized corrosion susceptibility of the WPOB in the 
repository. As discussed above, localized corrosion will only occur when Ecorr is equal to or 
greater than a critical potential (the crevice repassivation potential (Ercrev) in the current model). 
That is, if Ecorr < Ercrev, general or passive corrosion will occur. 
The specimens used to evaluate Ecorr of Alloy 22 as a function of immersion time were machined 
from sheet and bar stock. There were two main groups of specimens, (1) Welded U-bend 
specimens and (2) Untested rod specimens. Welded plus aged samples in 
DTN: LL040402212251.084 [DIRS 170097] were not considered in this analysis because the 
aging treatment was more severe (700C for 173 hours) than could reasonably be expected in the 
repository environment (Figure 6-2). Approximately half of the U-bend specimens tested for 
long-term corrosion potential were from the Long Term Corrosion Test Facility (LTCTF), and 
the other half of the U-bend specimens were not previously exposed to any electrochemical test 
condition. The U-bend specimens from the LTCTF already had a solution formed passive film 
and other surface alterations from exposure in the LTCTF. Both types of U-bend specimens were 
tested in the as-received (AR) or as-machined conditions, which corresponded to a root-meansquare 
roughness of 32  inch. The U-bend specimens were fabricated from -in. (19.05 mm) 
wide and 1/16-in. (1.588 mm) thick metal strips according to ASTM G 30-94 (1994 
[DIRS 137688]). The specimens were degreased in acetone and alcohol before testing. During 
the long-term open-circuit corrosion potential monitoring, the U-bend specimens were fully 
immersed in the electrolyte of interest. The rod specimens were all previously untested. Rod 
specimens were  in. (6.35 mm) in diameter and 12 in. (304.8 mm) long. They were polished 
with 600-grit paper and degreased with acetone and alcohol before testing. The data and test 
details reported in DTNs: LL020711612251.017 [DIRS 161204] and LL040402112251.083 
[DIRS 170283] are summarized in Appendix V. 
The samples are identified by a combination of letters and numbers. In earlier tests 
(DTN: LL020711612251.017 [DIRS 161204]), these were either DUB or DEA followed by 
three or four digits. The letter D stands for Alloy 22, the second letter stands for the type of 
sample, that is, U for U-bend specimen and E for electrochemical (or rod) specimen. The third 
letter could be either an A (mill annealed or not welded) or B (contains weld material). In the 
newer tests, some rod specimens were designated starting with the letters JE (for John Estill) or 
KE (for Kenneth Evans) followed by four digits. One specimen tested in BSW solution (Cell 4) 
was a double U-bend specimen and had a longer designation (ARC22 U20A and ARC22 U20B). 
Many different electrolyte solutions were used in the tests (Appendix V for the type of solutions 
tested). These included four multi-ionic solutions and other simpler salt solutions. The solutions 
from the LTCTF tanks (i.e., SDW, SAW, and SCW) are referred to as aged solution 
(approximately 4.5-years old at the time the tests started). The multi-ionic solutions that were 
freshly prepared (not from the LTCTF tanks) are referred to as fresh solution. For some 
solution compositions, more than one temperature was used for testing (Appendix V). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-74 October 2004 
The volume of the electrolyte solution in each cell was two liters. The electrolyte solutions were 
naturally aerated; that is, a stream of air was circulated above the level of the solution. This 
stream of air exited the vessel through a condenser to avoid evaporation of the electrolyte. The 
electrochemical potentials are reported in the saturated silver silver chloride scale (SSC). At 
ambient temperature, the SSC scale with the reference electrode in a saturated KCl solution 
is 199 mV more positive than the standard hydrogen electrode (SHE) (Sawyer and Roberts 1974 
[DIRS 162259], pp. 39 to 45, Table 2-4). The values of the corrosion potentials for each 
specimen (electrode) were acquired using a commercial data acquisition unit that had the input 
resistance set at 10  109 ohm. Typically, the measurements were acquired every minute for the 
first week of testing and every hour after the first week. The data was logged into the internal 
memory of the data acquisition unit and simultaneously to a spreadsheet in an interfaced personal 
computer. Data back up was performed monthly. 
The long-term corrosion potential behavior of some Alloy 22 samples in SDW, SAW, and SCW 
solutions from the LTCTF are shown in Figure 6-45. The data plotted in Figure 6-45 was taken 
weekly from the raw Ecorr versus time data contained in DTNs: LL020711612251.017 
[DIRS 161204] and LL040402112251.083 [DIRS 170283]. Step-function discontinuities shown 
in the graphs indicate periodic changes of reference electrodes. Figure 6-45 shows that after an 
initial period of 300 to 400 days, the Ecorr did not change substantially with time. It is shown that 
the results of the welded U-bend samples (samples DUB052 and DUB159) and (nonwelded) rod 
samples (samples DEA2850, DEA2851, and DEA2852) in aged SAW at 90C show no 
significant differences in their long-term open-circuit corrosion potential behaviors. Figure 6-45 
shows two sets of Ecorr versus time curves for Alloy 22. In the acidic multi-ionic SAW solution 
the potentials tended to be in the +200 to +400 mV versus SSC range while in the alkaline multiionic 
solutions SDW and SCW, the potentials tended to be in the 100 to +100 mV versus 
SSC range. In the SAW solution, the potential was higher at 60C and 90C than at 25C. 
Figure 6-46 compares the long-term corrosion potential evolution of freshly polished Alloy 22 
rods in freshly prepared SAW at 90C (Cell 9) with the corrosion potential evolution of the 
welded U-bend and rod samples in aged SAW at 90C (Figure 6-45) for the first 150 days of 
testing. Initially the Alloy 22 rods in the fresh SAW solution had the corrosion potential on the 
order of about 150 mV versus SSC. Over approximately 50 days of testing, the corrosion 
potential increased rapidly to a more noble potential value of approximately 330 mV versus SSC. 
Figure 6-45 shows that for the remainder of the testing time, the corrosion potential slowly 
reached a maximum value near 400 mV versus SSC. This high value of Ecorr is probably due to 
the formation of a more protective chromium rich oxide film on the Alloy 22 electrodes. The 
test results show that, regardless of the initial condition of the metal surface or the age of the 
electrolyte solution, eventually Alloy 22 undergoes ennoblement in SAW. This ennoblement is 
probably promoted by both the pH value and the presence of nitrate in the solution (Estill et al. 
2003 [DIRS 163849]). Such an ennoblement of Alloy 22 with time has also been reported 
elsewhere, and it was observed that the ennoblement was more significant in acidic solutions 
(Jayaweera et al. 2003 [DIRS 162225], Figures 9.12 and 9.13; Dunn et al. 2003 [DIRS 164138], 
Figures 8 and 9). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-75 October 2004 
Alloy 22 Long-Term Open-Circuit Corrosion Potentials 
(Naturally Aerated Condition) 
-0.40 
-0.30 
-0.20 
-0.10 
0.00 
0.10 
0.20 
0.30 
0.40 
0.50 
0 200 400 600 800 1000 1200 1400 
Time (Days) 
Potential (V vs SSC) 
DEA2802 Rod Aged SAW 25C 
DEA2807 Rod Aged SAW 25C 
DEA2859 Rod Aged SAW 25C 
DUB028 Welded UB Aged SAW 60C 
DUB157 Welded UB Aged SAW 60C 
DUB052 Welded UB Aged SAW 90C 
DUB159 Welded UB Aged SAW 90C 
DEA2850 Rod Aged SAW 90C 
DEA2851 Rod Aged SAW 90C 
DEA2852 Rod Aged SAW 90C 
DUB088 Welded UB Aged SCW 60C 
DUB156 Welded UB Aged SCW 60C 
DUB112 Welded UB Aged SCW 90C 
DUB161 Welded UB Aged SCW 90C 
DUB128 Welded UB Aged SDW 60C 
DUB160 Welded UB Aged SDW 60C 
DUB132 Welded UB Aged SDW 90C 
DUB162 Welded UB Aged SDW 90C 
SAW 25 C Rod
SAW 60 C UB 
SAW 90 C UB 
SAW 90 C Rod 
SCW 60 C UB 
SCW 90 C UB 
SDW 90 C UB 
SDW 60 C UB 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-45. Open-Circuit Corrosion Potential of Alloy 22 Samples as a Function of Time in Different 
Types of LTCTF Solutions 
Figure 6-47 shows the Ecorr of Alloy 22 in pure CaCl2 solutions and in CaCl2 + Ca(NO3)2 
solutions as a function of testing time. Even though the solutions containing nitrate were kept at 
90C and the pure CaCl2 solution were kept at 120C, a few observations can be made regarding 
the influence of nitrate ions on the long-term corrosion potential. In the pure CaCl2 solution, the 
corrosion potential reached steady state at approximately 130 mV versus SSC in less than 100 
days and then the potential remained more of less stable for the next two years. For the pure 
chloride solution the corrosion potential was steady (i.e., had little noise or perturbations). In the 
solution in which the ratio of nitrate-to-chloride was 1 (1 M CaCl2 + 1 M Ca(NO3)2), the 
corrosion potential of Alloy 22 raised rapidly in the first 100 days of testing and then more 
slowly for the next 500 days stabilizing at approximately +300 mV versus SSC. The value of the 
corrosion potential was practically free of noise. In the solution with a nitrate-to-chloride ion 
ratio of 0.1, the corrosion was raised less rapidly than in the one to one ratio solution and at the 
end the corrosion potential stabilized at approximately +200 mV versus SSC (Figure 6-47). In 
the cell that contained the solution with a nitrate-to-chloride ion ratio of 0.01 (5 M CaCl2 + 
0.05 M Ca(NO3)2), the corrosion potential of Alloy 22 was the least steady. In general, the 
corrosion potential raised as the time increased but it had large fluctuations of almost 400 mV 
and it was the least reproducible of the four systems represented. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-76 October 2004 
Alloy 22 Long Term Open-Circuit Corrosion Potentials 
(Naturally Aerated Condition) 
-0.20 
-0.10 
0.00 
0.10 
0.20 
0.30 
0.40 
0.50 
0 30 60 90 120 150 
Time (Days) 
Potential (V vs SSC) 
DUB052 Welded U-Bend in Aged 
SAW 90C 
DUB159 Welded U-Bend in Aged 
SAW 90C 
DEA2850 Rod in Aged SAW 90C 
DEA2851 Rod in Aged SAW 90C 
DEA2852 Rod in Aged SAW 90C 
DEA2797 Rod in Fresh SAW 90C 
DEA2853 Rod in Fresh SAW 90C 
DEA2881 Rod in Fresh SAW 90C 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-46. Open-Circuit Corrosion Potential of Alloy 22 Samples as a Function of Time in Differing 
Conditions of SAW Solutions 
Figure 6-48 and Figure 6-49 show the steady state open-circuit potentials (or corrosion 
potentials) of the Alloy 22 specimens from Appendix V used for the model and analysis as a 
function of chloride ion concentration and nitrate ion concentration, respectively. Figure 6-48 
and Figure 6-49 show that sample geometry and metallurgical condition (e.g., MA versus ASW) 
have a negligible effect on the long-term steady-state corrosion potential of Alloy 22. Figure 
6-48 shows that in general, for the solutions containing little or no nitrate ions, the corrosion 
potential decreases with chloride ion concentration, which is consistent with the fact that higher 
chloride ion concentrations make the metal more active (e.g., see potentials from SDW, 4 M 
NaCl and 5 M CaCl2 solutions, Cells 5, 6, 18 and 8). Also, part of the decrease in potential with 
increasing chloride ion concentration may be due to the salting out effect (i.e., dissolved 
oxygen content decreases with increasing salt concentration) (Langmuir 1997 [DIRS 100051], 
Chapter 4). However, when nitrate is present in the solution even in small amounts 
(e.g., NO3/Cl = 0.01 in Cell 14) and even in high chloride solutions, the corrosion potential 
seems more controlled by nitrate rather than by chloride. Figure 6-49 shows the corrosion 
potential as a function of the nitrate ion concentration in the solutions. In general, Ecorr increases 
as the nitrate ion concentration increases. However, an effect of chloride ion may also be 
superimposed, since Ecorr is higher when the base chloride ion concentration is lower. For 
example, for Cell 15, Ecorr is lower than the corresponding value for that nitrate ion concentration 
(1.26 m) since the base concentration of chloride is high (12.6 m). At high chloride ion 
concentrations, for the BSW solution, the potential is lower than predicted by a one to one Ecorr 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-77 October 2004 
versus nitrate ion solution since in this solution Ecorr seems to be controlled more by the pH of 
the solution. 
Alloy 22 Long Term Open-Circuit Corrosion Potentials 
(Naturally Aerated Condition) 
-0.40 
-0.30 
-0.20 
-0.10 
0.00 
0.10 
0.20 
0.30 
0.40 
0 100 200 300 400 500 600 700 800 900 1000 
Time (Days) 
Potential (V vs SSC) 
DEA3087 Rod in 1M CaCl2+1M Ca(NO3)2 90C 
DEA3088 Rod in 1M CaCl2+1M Ca(NO3)2 90C 
DEA2800 Rod in 5M CaCl2+0.05M Ca(NO3)2 90C 
DEA2801 Rod in 5M CaCl2+0.05M Ca(NO3)2 90C 
DEA2805 Rod in 5M CaCl2+0.5M Ca(NO3)2 90C 
DEA2806 Rod in 5M CaCl2+0.5M Ca(NO3)2 90C 
DEA105 Rod in 5M CaCl2 120C 
DEA106 Rod in 5M CaCl2 120C 5 M CaCl2 at 120 C 
1 M CaCl2 + 
1 M Ca(NO3)2 at 90 C 
5 M CaCl2 + 
0.5 M Ca(NO3)2 
at 90 C 
5 M CaCl2 + 
0.05 M Ca(NO3)2 
at 90 C 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-47. Open-Circuit Corrosion Potential of Alloy 22 Samples as a Function of Time in Differing 
Concentrations of CaCl2 Solutions 
Figure 6-50 shows that in general the steady-state corrosion potential decreases as the pH of the 
solution increases. The only points lower than the rest of the trend are the potentials for the 
solutions containing high chloride such as in Cell 8 (5M CaCl2) and in Cell 18 (4 M NaCl). In 
these latter cells, the potential is more controlled by the chloride concentration rather than by the 
pH of the solution. Although not shown in the figure, the corrosion potential of Alloy 22 is 
expected to drop sharply for very low pH conditions (lower than those shown in the figure) 
because the passive film on the alloy would become unstable in such extreme acidic conditions 
and the alloy would become more active. 
In general, Figure 6-48 through Figure 6-50 show that the corrosion potential is a complex 
function of several variables, including the concentration of chloride, nitrate and the pH of the 
electrolyte solution. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-78 October 2004 
Alloy 22 Long-Term Open-Circuit Corrosion Potential vs. [Cl-] 
(naturally aerated condition) 
-300 
-200 
-100
0 
100 
200 
300 
400 
500
0 2 4 6 8 10 12 14 
Chloride Concentration (m, moles/kg water) 
Corrosion Potential (mV vs SSC) 
ASW UB SAW 60C - Cell 1 
ASW UB SAW 90C - Cell 2 
ASW UB SCW 90C - Cell 3 
ASW UB SDW 60C - Cell 5 
ASW UB SDW 90C - Cell 6 
ASW UB BSW 105C - Cell 4 
MA UB BSW 105C - Cell 4 
MA Rod 5 M CaCl2 120C - Cell 8 
MA Rod Fresh SAW 90C - Cell 9 
MA Rod SAW 90C - Cell 10 
MA Rod SAW 25C - Cell 7N 
MA Rod 1M CaCl2, NO3/Cl=1, 90C - Cell 13 
MA Rod 5 M CaCl2, NO3/Cl=0.01, 90C - Cell 14 
MA Rod 5 M CaCl2, NO3/Cl=0.1, 90C - Cell 15 
MA Rod Fresh SCW 90C Cell 16 
ASW Rod Fresh SCW 90C - Cell 16 
MA Rod SAW w/out Silicate 90C - Cell 17 
ASW Rod SAW w/out Silicate 90C - Cell 17 
MA Rod 4 M NaCl 90C - Cell 18 
ASW Rod 4 M NaCl 90C - Cell 18 
ASW Rod NO3/Cl=1, 90C - Cell 13 
ASW Rod NO3/Cl=0.01, 90C - Cell 14 
ASW Rod NO3/Cl=0.1, 90C - Cell 15 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-48. Long-Term Open-Circuit Corrosion Potential Versus Chloride Ion Concentration of Alloy 22 
Samples with Differing Sample Configurations and Metallurgical Conditions 
Alloy 22 Long-Term Open-Circuit Corrosion Potential vs. [NO3-] 
(naturally aerated condition) 
-300 
-200 
-100
0 
100 
200 
300 
400 
500
0.0 0.5 1.0 1.5 2.0 2.5 3.0 
Nitrate Concentration (m, moles/kg water) 
Corrosion Potential (mV vs. SSC) 
ASW UB SAW 60C - Cell 1 
ASW UB SAW 90C - Cell 2 
ASW UB SCW 90C - Cell 3 
ASW UB SDW 60C - Cell 5 
ASW UB SDW 90C - Cell 6 
ASW UB BSW 105C - Cell 4 
MA UB BSW 105C - Cell 4 
MA Rod 5 M CaCl2 120C - Cell 8 
MA Rod Fresh SAW 90C - Cell 9 
MA Rod SAW 90C - Cell 10 
MA Rod SAW 25C - Cell 7N 
MA Rod 1M CaCl2, NO3/Cl=1, 90C - Cell 13 
MA Rod 5 M CaCl2, NO3/Cl=0.01, 90C - Cell 14 
MA Rod 5 M CaCl2, NO3/Cl=0.1, 90C - Cell 15 
MA Rod Fresh SCW 90C - Cell 16 
ASW Rod Fresh SCW 90C - Cell 16 
MA Rod SAW w/out Silicate 90C - Cell 17 
ASW Rod SAW w/out Silicate 90C - Cell 17 
MA Rod 4 M NaCl 90C - Cell 18 
ASW Rod 4 M NaCl 90C - Cell 18 
ASW Rod NO3/Cl=1, 90C - Cell 13 
ASW Rod NO3/Cl=0.01, 90C - Cell 14 
ASW Rod NO3/Cl=0.1, 90C - Cell 15 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-49. Long-Term Open-Circuit Corrosion Potential Versus Nitrate Ion Concentration of Alloy 22 
Samples with Differing Sample Configurations and Metallurgical Conditions 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-79 October 2004 
Alloy 22 Long-Term Open-Circuit Corrosion Potential vs. pH 
(naturally aerated condition) 
-300 
-200 
-100
0 
100 
200 
300 
400 
500
2 3 4 5 6 7 8 9 10 11 12 
pH 
Corrosion Potential (mV vs SSC) 
ASW UB SAW 60C- Cell 1 
ASW UB SAW 90C - Cell 2 
ASW UB SCW 90C- Cell 3 
ASW UB SDW 60C- Cell 5 
ASW UB SDW 90C- Cell 6 
ASW UB BSW 105C - Cell 4 
MA UB BSW 105C - Cell 4 
MA Rod 5 M CaCl2 120C - Cell 8 
MA Rod Fresh SAW 90C - Cell 9 
MA Rod SAW 90C - Cell 10 
MA Rod SAW 25C - Cell 7N 
MA Rod 1M CaCl2, NO3/Cl=1, 90C - Cell 13 
MA Rod 5 M CaCl2, NO3/Cl=0.01, 90C - Cell 14 
MA Rod 5 M CaCl2, NO3/Cl=0.1, 90C - Cell 15 
MA Rod Fresh SCW 90C - Cell 16 
ASW Rod Fresh SCW 90C - Cell 16 
MA Rod SAW w/out Silicate 90C - Cell 17 
ASW Rod SAW w/out Silicate 90C - Cell 17 
MA Rod 4 M NaCl 90C - Cell 18 
ASW Rod 4 M NaCl 90C - Cell 18 
ASW Rod NO3/Cl=1, 90C - Cell 13 
ASW Rod NO3/Cl=0.01, 90C - Cell 14 
ASW Rod NO3/Cl=0.1, 90C - Cell 15 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-50. Long-Term Open-Circuit Corrosion Potential Versus pH of Alloy 22 Samples with Differing 
Sample Configurations and Metallurgical Conditions 
6.4.4.5 Long-Term Corrosion Potential Model 
The data reported in Appendix V were used to build a model for the long-term corrosion 
potential of the WPOB. For the long-term corrosion potential model, only the Ecorr data after an 
immersion time of 328 days and higher were used. The criteria of data selection were based on 
one-year immersion (or a fraction thereof equal or higher than 0.9). In some systems (Cell 8 
(5 M CaCl2) in Figure 6-47) the Ecorr seemed to stabilize in the first 50 days of exposure; 
however, in other systems such as in Cell 14 (5 M CaCl2 + 0.05 M Ca(NO3)2) in Figure 6-47 
Ecorr shows signs of instability even after two years of exposure. That is, it is considered 
appropriate to use an average of one-year immersion time to be reasonably assured that most of 
the cells have stabilized as much as possible. Because of measurement noise in the long-term 
corrosion potentials, an average of the readings for the final week of exposure for each sample 
was used as the steady-state value for the model analysis. The data that were obtained are listed 
in Appendix V. Development of the long-term corrosion potential model for the WPOB was 
performed considering a set of multiple regression models as a function of the test exposure 
environment parameters such as temperature, pH, chloride concentration and nitrate 
concentration. 
The initial models were fit to the long-term corrosion potential data (Ecorr) listed in Appendix V, 
and evaluated for the goodness of their model fit using various statistical analysis techniques. 
Among the models that were considered, the following functional form was found to adequately 
describe the relationship between Ecorr and the test environment variables above. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-80 October 2004 
. .. 
. 
. .. 
. 
+ + + + = -
- 
- 
] [ 
] [ 
log ] [ 3 
4 3 2 1 Cl 
NO 
c Cl c pH c T c c E o corr (Eq. 6-36) 
where T is the temperature (C), ] [ - Cl is the chloride ion concentration in molality (m, moles/kg 
water), ] [ 3
- NO is the molal nitrate ion concentration, and co, c1, c2, c3, and c4 are coefficients of 
the model parameters. Using the method of least squares, the above model was fitted to the data 
in Appendix V. The model fitting was performed using Mathcad version 11.1, and the Mathcad 
worksheet for the model fitting is found in the output DTN: MO0409MWDULCMW.000 and in 
Appendix IX.3. For the data with no nitrate ions, a very small value of 10-8 m was used for the 
nitrate ion concentration in the regression analysis. 
The estimated regression coefficients and their uncertainty (1 standard deviation) are: 
= 0 c 558.283  36.156, = 1 c 0.677  0.413, = 2 c -65.338  2.456, = 3 c -7.616  1.581, and 
= 4 c 37.077  2.443. The covariance matrix resulting from the fitting procedure was determined 
to be: 
. . . . . . 
.
. 
. . . . . . 
.
. 
     - 
    -  
    -  - 
  -  -   - 
 -   -  -  
= 
- - 
- - 
- - - 
- - - - 
0 0 1 1 1 
0 0 1 1 0 
1 1 0 2 1 
1 1 2 1 1 
1 0 1 1 3 
10 969 . 5 10 510 . 1 10 611 . 6 10 599 . 2 10 149 . 2 
10 510 . 1 10 501 . 2 10 349 . 7 10 678 . 1 10 751 . 3 
10 611 . 6 10 349 . 7 10 033 . 6 10 595 . 8 10 595 . 2 
10 599 . 2 10 678 . 1 10 595 . 8 10 708 . 1 10 345 . 1 
10 149 . 2 10 751 . 3 10 595 . 2 10 345 . 1 10 307 . 1 
CV (Eq. 6-37) 
The correlation coefficient R for the fit is 0.973, and the coefficient of determination R is 0.947. 
An R2 value of 0.947 indicates that the regression model fits the experimental data very well. 
The entire variance of the model is due to the measurement uncertainty. The same logic as the 
crevice repassivation potential data (i.e., ASTM G 61-86 (1987 [DIRS 127897]) discussed in 
Section 6.4.4.3.1) was used to quantify the uncertainty of the long-term corrosion potential data. 
As with the crevice repassivation potential model, the uncertainty in the steady-state corrosion 
potential model is limited to the range between 2 standard deviations of the meanthis 
includes 95 percent of all variation provided random variations are the only source of error. This 
uncertainty range is sufficient as the data are highly reproducible (Estill et al. 2003 
[DIRS 163849]). 
For the waste package degradation analysis in the repository, variability in the corrosion 
potential among waste packages is represented by the temporally and spatially varying waste 
package temperature and chemistry of water contacting the waste package. The purpose of this 
long-term corrosion potential model is to estimate the long-term steady-state open-circuit 
corrosion potential of Alloy 22 for a range of exposure conditions related to the repository. The 
model is not intended for short-term transient conditions. 
The model results and the steady-state corrosion potential data are shown in Figure 6-51 and 
Figure 6-52 as a function of pH and nitrate concentration, respectively. The steady state Ecorr 
values are the same as those shown in Figure 6-48 through Figure 6-50. Note the model results 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-81 October 2004 
are for the average values of the test environment parameters (temperature, chloride 
concentration and pH) of the source data. The Ecorr data for the test conditions off the average 
values, therefore, are not bound within  2 standard deviations of the model mean. The figures 
show that the steady-state corrosion potential is a strong function of both pH and nitrate 
concentration (at low nitrate concentrations). 
Figure 6-51 shows a strong dependence of the steady-state corrosion potential on pH. The model 
predicts that the corrosion potential changes at a rate of about 65 mV per pH unit. This model 
behavior represents the effect of ennoblement in Ecorr of the alloy in acidic conditions as seen in 
the SAW solutions (Figure 6-46). Other investigators also reported such an ennoblement of 
Alloy 22 in acidic conditions (Dunn et al. 2003 [DIRS 164138], Figures 8 and 9; Jayaweera et al. 
2003 [DIRS 162225], Section 9.3.2, Figure 9.13). The corrosion potential of Alloy 22 is 
expected to drop sharply for very low pH conditions because the passive film on the alloy would 
become unstable in such extreme acidic conditions and the alloy would become more active. 
The current model does not represent this. 
As shown in Figure 6-52, for the mean chloride ion concentration of 3.96 m, the corrosion 
potential increases as the nitrate ion concentration increases for low nitrate concentrations, but 
has little dependence on nitrate concentration for higher nitrate concentrations. To be consistent 
with the evaluation method for Ercrev in Section 6.4.4.3.2, if the exposure nitrate-to-chloride ion 
concentration ratio exceeds 0.5, the value 0.5 is used in evaluating the model. Nitrate is an 
oxidizing anion and, therefore, promotes the passivation of Alloy 22, thus increasing the Ecorr. 
The model prediction represents the experimental data well. It can be seen from the coefficient 
of the temperature term that the corrosion potential is a weak function of temperature and 
increases slightly with temperature. This may be due to passive film becoming more defect-free 
at higher temperatures (Lloyd et al. 2003 [DIRS 167921]) as the defect repair processes in the 
passive film could become accelerated as temperature increases. Other variables such as pH and 
nitrate concentration seem more important in controlling the Ecorr of Alloy 22 than the 
temperature. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-82 October 2004 
Ecorr vs. pH for Varying Chloride and Nitrate Ion Concentrations 
-300 
-200 
-100
0 
100 
200 
300 
400 
500
2 3 4 5 6 7 8 9 10 11 12 
pH 
Ecorr (mV vs. SSC) 
pH 2.8-5 
pH 6-9 
pH 9.7-11 
Model Mean 
Mean -1sd 
Mean +1sd 
Mean -2sd 
Mean +2sd 
Output DTN: MO0409MWDULCMW.000. 
NOTE: The model calculations are for the mean values of temperature (88.1C), chloride concentration (3.96 m), 
and nitrate concentration (0.58 m) of the long-term corrosion potential data of Alloy 22 used for the model 
development. 
Figure 6-51. Model Results and Experimental Data for Long-Term Ecorr of the Waste Package Outer 
Barrier as a Function of pH 
Ecorr vs. Nitrate Ion Concentration 
-300 
-200 
-100
0 
100 
200 
300 
400 
500
0.0 0.5 1.0 1.5 2.0 2.5 3.0 
Nitrate Ion Concentration (m) 
Ecorr (mV vs. SSC) 
All Data 
Model Mean 
Mean -1sd 
Mean +1sd 
Mean -2sd 
Mean +2sd 
Output DTN: MO0409MWDULCMW.000. 
NOTE: The model calculations are for the mean values of temperature (88.1C), pH (5.27), and chloride 
concentration (3.96 m) of the long-term corrosion potential data of Alloy 22 used for the model development. 
Figure 6-52. Model Results and Experimental Data for Long-Term Ecorr of the Waste Package Outer 
Barrier as a Function of Nitrate Ion Concentration 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-83 October 2004 
6.4.4.6 Analysis of Localized Corrosion Initiation Model 
In the localized corrosion initiation model, localized corrosion of the WPOB occurs when the 
open-circuit corrosion potential (Ecorr) is equal to or greater than a critical potential (the crevice 
repassivation potential (Ercrev) in the current model), that is, .E (=Ercrev - Ecorr) = 0. This 
conceptual model of localized corrosion initiation is widely accepted by the corrosion 
community and has been published extensively (Bhni 2000 [DIRS 164137], Section B; Dunn et 
al. 2000 [DIRS 164495]; Dunn et al. 2003 [DIRS 164138]; Frankel 1998 [DIRS 162216]; 
Frankel 2002 [DIRS 164140]; Frankel and Kelly 2002 [DIRS 164141]; Beavers et al. 2002 
[DIRS 158781], Section 8.3). For the current localized corrosion initiation model a conservative 
measure, the crevice repassivation potential (Ercrev), was used for the critical potential. For the 
same or similar metallurgical conditions (mill annealed or as-welded), the localized corrosion 
initiation model components (i.e., Ecorr and Ercrev) could be affected by the exposure condition 
(temperature, pH, chloride ion concentration, nitrate ion concentration). 
This section documents the analysis of the localized corrosion initiation model for long-term 
localized corrosion susceptibility of the WPOB for a range of environmental conditions of 
interest. The analyses were performed by comparing the crevice repassivation potential model 
results with the long-term corrosion potential model results, as described above. The analyses 
were conducted with Mathcad version 11.1 (the Mathcad worksheet files are included in the 
output DTN: MO0409MWDULCMW.000). The localized corrosion initiation model is 
intended to be used to analyze the long-term localized corrosion susceptibility of the WPOB, and 
not for analysis of short-term transient behavior. 
6.4.4.6.1 Localized Corrosion Susceptibility Versus Temperature for 10 Molal Chloride 
and pH 7 Condition with Varying Nitrate Concentrations. 
Figure 6-53 shows the model results for the localized corrosion susceptibility of the WPOB for a 
neutral-pH concentrated chloride-containing brine (10 m (moles/ kg water) chloride) with a very 
low nitrate ion concentration (NO3/Cl ratio = 0.05). The mean critical temperature for localized 
corrosion (crevice corrosion) for this condition is about 81C. The upper bound of the critical 
temperature, obtained from the intersection of the +2 standard deviation confidence bound of the 
crevice repassivation potential and the -2 standard deviation confidence bound of the corrosion 
potential, is about 99C. The lower bound of the critical temperature, obtained from the 
intersection of the -2 standard deviation confidence bound of the crevice repassivation potential 
and the +2 standard deviation confidence bound of the corrosion potential, is about 51C. 
As shown in Figure 6-54, with an increase of nitrate concentration to 1.5 m (NO3/Cl 
ratio = 0.15), the mean critical temperature increases to about 112C, and the lower bound 
critical temperature is about 94C. 
With a further increase of nitrate concentration to 2.5 m (NO3/Cl ratio = 0.25), the model predicts 
that crevice corrosion is not possible below 120C (Figure 6-55), which is above or at least close 
to the boiling temperature of a 10 molal chloride-containing solution. Therefore, it is concluded 
that for neutral pH chloride-containing brines, the WPOB will not undergo localized corrosion 
when the nitrate ion concentration is higher than 2.5 m. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-84 October 2004 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-53. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Temperature for 10 m Chloride, pH 7, and 0.5 m Nitrate (NO3/Cl Ratio of 0.05) 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-54. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Temperature for 10 m Chloride, pH 7, and 1.5 m Nitrate (NO3/Cl Ratio of 0.15) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-85 October 2004 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-55. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Temperature for 10 m Chloride, pH 7, and 2.5 m Nitrate (NO3/Cl Ratio of 0.25) 
6.4.4.6.2 Localized Corrosion Susceptibility Versus Temperature for 10 Molal Chloride 
and pH 3 (Acidic Condition) with Varying Nitrate Concentrations. 
Concentrated chloride-containing hot brines become more corrosive as the pH is lowered (more 
acidic conditions). Although hot acidic chloride-dominant concentrated brines are not expected 
to form on the waste package surface from the dust leachates under the drip shield, analyses were 
performed to identify potential exposure conditions in which localized corrosion of the WPOB is 
possible. 
Figure 6-56 shows the model results, as a function of temperature, for an acidic chloridedominant 
concentrated brine (10 m chloride) with a very low nitrate concentration (NO3/Cl ratio 
of 0.05). The model predicts that the WPOB is subject to localized corrosion (crevice corrosion) 
over the entire temperature range investigated. However, an increase of nitrate concentration 
to 2.5 m (NO3/Cl ratio of 0.25) results a mean critical temperature around room temperature, and 
an upper bound critical temperature of about 50C (Figure 6-57). 
As shown in Figure 6-58, with a further increase of nitrate concentration to 5 m (NO3/Cl ratio 
of 0.50), the model predicts a lower bound critical temperature of about 93C, a mean critical 
temperature of about 111C, and the possibility of localized corrosion at temperatures 
above 120C (near the boiling point of a 10 molal chloride-containing solution). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-86 October 2004 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-56 Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Temperature for 10 m Chloride, pH 3, and 0.5 m Nitrate (NO3/Cl Ratio of 0.05) 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-57. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Temperature for 10 m Chloride, pH 3, and 2.5 m Nitrate (NO3/Cl Ratio of 0.25) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-87 October 2004 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-58. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Temperature for 10 m Chloride, pH 3, and 5 m Nitrate (NO3/Cl Ratio of 0.50) 
6.4.4.6.3 Localized Corrosion Susceptibility Versus Chloride Concentration for 95C and 
pH 7 with Varying Nitrate Concentrations. 
Analyses were performed to evaluate the model for the localized corrosion susceptibility of the 
WPOB as a function of chloride ion concentration. Because chloride-containing brines with 
neutral pH conditions are one of the likely water chemistries expected to contact the waste 
packages in the postclosure repository, analyses were performed for neutral pH chloridecontaining 
brines at 95C. 
Figure 6-59 shows the model results for neutral pH chloride-containing brines with a very low 
nitrate concentration (0.01 m) at 95C. The model predicts that, at 95C and with little or no 
nitrate ions present, the WPOB is subject to crevice corrosion for chloride concentrations from 
about 7 m (using the mean Ercrev and Ecorr values) down to about 2.5 m. The model predicts 
crevice corrosion is possible (although may not always occur) down to very low chloride 
concentrations. Crevice corrosion susceptibility in very low chloride concentrations is consistent 
with the CNWRA data, which reported the occurrence of crevice corrosion in 0.005 and 0.05 M 
chloride at 95C and pH 6 (Brossia et al. 2001 [DIRS 159836], Table A-1). As shown in Figure 
6-59, the model also predicts crevice corrosion is possible (although may not always occur) for 
higher chloride concentrations (i.e., above about 7 m). 
Figure 6-60 shows that with an increase of nitrate concentration to 2.5 m, crevice corrosion of the 
WPOB is avoided over the modeled chloride ion concentration range in 95C neutral chloride 
brines. The curves in Figure 6-60 show a change in slope at a chloride ion concentration of 5 m 
because the nitrate-to-chloride ion ratio exceeds 0.50 at this concentration and, as discussed 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-88 October 2004 
previously, the models are evaluated at a constant nitrate-to-chloride ion ratio of 0.50 under those 
conditions. This further confirms the conservatism in the evaluation method (limiting the nitrate 
to chloride ratio to 0.5) used. 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-59. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Chloride Concentration for 95C, pH 7, and 0.01 m Nitrate 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-89 October 2004 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-60. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Chloride Concentration for 95C, pH 7, and 2.5 m Nitrate 
6.4.4.6.4 Localized Corrosion Susceptibility Versus pH for 95C and 10 Molal Chloride 
with Varying Nitrate Concentrations. 
Figure 6-61 shows the model results for the localized corrosion susceptibility as a function of pH 
for concentrated chloride-dominant brines (10 m) with a low nitrate concentration (or no nitrate) 
(0.01 m, NO3/Cl ratio = 0.001) at 95C. The model predicts that crevice corrosion does not 
occur for neutral and alkaline conditions (pH above about 7.5) from the mean-value estimation. 
The lower and upper bound pH values are about 6.8 and 8.0, respectively. 
As shown in Figure 6-62, an increase of nitrate concentration to 2.5 m (NO3/Cl ratio = 0.25) 
extends the pH bound for no crevice corrosion into more acidic conditions for the modeled 
chloride brines: pH about 5.3 from the mean estimation, pH about 4.8 from the lower bound 
estimation, and pH 5.8 from the upper bound estimation. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-90 October 2004 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-61. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of pH for 95C, 10 m Chloride, and 0.01 m Nitrate (NO3/Cl Ratio of 0.001) 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-62. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of pH for 95C, 10 m Chloride, and 2.5 m Nitrate (NO3/Cl Ratio of 0.25) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-91 October 2004 
6.4.4.6.5 Localized Corrosion Susceptibility Versus Nitrate Ion Concentration for 95C 
and 10 Molal Chloride for Neutral (pH 7) and Acidic (pH 3) Conditions. 
Analyses were performed to evaluate the effect of inhibitive nitrate ion concentration on the 
localized corrosion susceptibility for neutral and acidic concentrated chloride-dominant brines 
at 95C. Figure 6-63 shows that, for the modeled 95C neutral chloride brines (10 m chloride 
and pH 7), a nitrate ion concentration higher than about 1.5 m (NO3/Cl ratio of 0.15) is needed to 
avoid crevice corrosion. However, as shown in Figure 6-64, for acidic concentrated chloride 
brines (10 m chloride ion and pH 3) at 95C, a significantly higher nitrate concentration is 
necessary to avoid initiation of crevice corrosion: about 4.8 m nitrate ion from the mean 
estimation (NO3/Cl ratio = 0.48), about 4.5 m nitrate from the lower-bound estimation 
(NO3/Cl ratio = 0.45), and about 5.2 m nitrate from the upper-bound estimation (NO3/Cl 
ratio = 0.52). 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-63. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Nitrate Concentration for 95C, pH 7, and 10 m Chloride 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-92 October 2004 
Output DTN: MO0409MWDULCMW.000. 
Figure 6-64. Model Results for Crevice Corrosion Susceptibility of the Waste Package Outer Barrier as a 
Function of Nitrate Concentration for 95C, pH 3, and 10 m Chloride 
6.4.4.6.6 Waste Package Outer Barrier Localized Corrosion at High Temperatures and 
Ionic Concentrations 
The waste package outer barrier localized corrosion initiation model consists of the long-term 
corrosion potential model and the crevice repassivation potential model. The crevice 
repassivation potential model was constructed using data from pure chloride solutions and mixed 
chloride and nitrate solutions, including some data at high nitrate (up to 18 m) and chloride (up 
to 36 m) concentrations and high temperatures (up to 160C). However, the long-term corrosion 
potential model was constructed using data from relatively dilute (in terms of chloride and nitrate 
ion content) mixed ionic solutions (e.g., SAW and SCW), pure chloride solutions (up to about 12 
m), and mixed chloride (up to about 13 m) and nitrate (up to about 2.6 m) solutions. The 
maximum temperature for any data point used in construction of the long-term corrosion 
potential model was 120C and no long-term corrosion potential data is available for use in 
validation. On this basis, the functional form developed for the long-term corrosion potential in 
Section 6.4.4.5 should only be used at 120C or below. Therefore, the criteria for localized 
corrosion initiation above 120C should be considered further. 
6.4.4.6.6.1 High Temperature Exposure Environments 
In this section, the repository exposure environment at temperatures in excess of 120C is 
discussed in relation to its effect on localized corrosion initiation on the waste package outer 
barrier. For intact or moderately degraded drifts, there is no seepage water contacting the waste 
package surface if the drift wall exposure temperature is above the boiling point of water in the 
drift (BSC 2004 [DIRS 169131], Section 6.5.2 and 8.1). The threshold temperature to define 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-93 October 2004 
boiling is 100C at the drift wall (BSC 2004 [DIRS 169131], Section 6.5.2). The waste package 
surface temperature is 120C or below when the drift wall exposure temperature is 100C or 
below (e.g., BSC 2004 [DIRS 169565], Figures 6.3-66 and 6.3-68). For collapsed drifts during 
the period of above boiling rock temperatures, ambient rock water boils off in the rubble material 
and in-drift flux perturbations give rise to moderate reflux of condensate in the upper half of 
collapsed drifts (BSC 2004 [DIRS 169131], Section 6.5.3, and 8.1). However, water drainage 
down to the waste packages is not possible, a result of the vaporization barrier forming near the 
waste package (BSC 2004 [DIRS 169131], Section 6.5.3). The vaporization and reflux processes 
cease after a few hundred to more than thousand years and the TH conditions slowly approach 
steady-state (ambient) behavior (BSC 2004 [DIRS 169131], Section 6.5.3). During this transition 
phase, the fluxes in the lower half of the collapsed drift remain zero at all times (BSC 2004 
[DIRS 169131], Section 6.5.3). Therefore, the relevant chemistries to consider for waste 
package surface temperatures above 120C are those which result from the interaction of water 
condensation with dusts films which may be present on the waste package surface (dust 
leachates). 
For water to be present on the waste package surface at temperatures above 120C, the water 
must be a concentrated solution such that the vapor pressure of the solution and the relative 
humidity (RH) of the water is reduced below that of pure water. Figure 6-65 (BSC 2004 
[DIRS 161237], Figure 3) shows the maximum RH (equivalent to the activity) for water to be 
present at a given exposure temperature. The figure shows, for example, that at 120C, the RH 
must be 45 percent or less for water to be present on the waste package surface with lower RH 
required at higher temperatures. For water to exist at such a low relative humidities, the water 
must be in a concentrated solution with other ions. Dust leachates at temperatures above 120C 
(below 45 percent RH) have high nitrate ion concentrations (on the order of 10 m nitrate) 
(BSC 2004 [DIRS 169860], Figure 6.13-39) and low chloride to nitrate ion ratios (BSC 2004 
[DIRS 169860], Figure 6.13-38) (i.e., high nitrate-to-chloride ion ratios). Given the inhibiting 
effect of nitrate ions and the nitrate-to-chloride ion ratio on localized corrosion initiation 
(Section 6.4.4.3.2), localized corrosion initiation would not be highly probable in these exposure 
environments. 
Another consideration relevant to the exposure environment at higher temperatures is acid gas 
volatility. Pulvirenti et al. (2004 [DIRS 169631]) have reported generating acid gas volatiles 
including HCl and HNO3 by concentrating (through boiling) various repository relevant 
solutions. These researchers trapped and condensed the volatiles and measured pH values less 
than 1. If these volatiles disperse to the drift wall and either diffuse or advect into it or be 
neutralized by reaction with the surrounding rock, as is likely in the open repository system, then 
acid gas volatility will limit the possibility of development of low pH (acidic conditions) on the 
waste package surface. Thermogravimetric experiments were conducted in which an Alloy 22 
sample surface was coated with an aerosol film of calcium chloride 
(DTN: LL030308812251.017 [DIRS 163775], LL020903812251.019 [DIRS 161135]). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-94 October 2004 
Source BSC 2004 [DIRS 161237], Figure 3 
Figure 6-65. Maximum RH for Wet Conditions as a Function of Temperature, for Repository Ambient 
Pressure (left) and Standard Atmospheric Pressure (right) 
Source: DTN: LL030308812251.017 [DIRS 163775]. 
Note: Variances in water mass absorbed through deliquescence are most likely due to slightly differing amounts of 
salt deposited during the coating process. Zero weight is the initial specimen weight. 
Figure 6-66. Comparison of Weight Changes of Alloy 22 Specimens Coated with a Thin Film of Calcium 
Chloride Exposed at 22.5% RH at the Various Temperatures Shown. 
The weight change was monitored as the sample was exposed to a constant relative humidity 
of 22.5 percent at 100C, 125C, and 150C as shown in Figure 6-66. Initially, at all 
temperatures the specimen weight increases due to the deliquescence process (i.e., a thin aqueous 
film is observed on the specimen surface). At 100C there was no observable change in weight 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-95 October 2004 
following the initial increase, and the specimen surface remained wet and visually unchanged 
throughout the test. At 125C a steady weight loss was observed for more than 600 hours. 
During this time, the specimen surface was observed to slowly become dry and precipitate 
formation was observed. At 150C a sharp decline in weight was observed following initial 
deliquescence, and reaction completion was reached in ~24 hours. Subsequent analyses 
indicated that the preciptates formed did not contain metal ions, suggesting the weight changes 
observed were not due to electrochemical reactions and no evidence of localized attack was 
observed. The precipitation reaction was coupled with the loss of chloride as HCl gas 
(DTN: LL020903812251.019 [DIRS 161135], Readme.pdf). Thus, experimental evidence 
suggestes that acid gas volatility limits the possible formation of low pH (acidic conditions) from 
evolution of calcium chloride-based brines at 125C and 150C, but may not at 100C. 
6.4.4.6.6.2 Corrosion Data Relevant to High Temperature Exposure Environments 
The previous section discussed the repository exposure environment at temperatures in excess of 
120C. This section discusses relevant data collected under these types of exposure conditions. 
Table 6-8 shows the high nitrate and chloride concentration data used in construction of the 
crevice repassivation model in the first 20 rows. The table also contains nine rows of data not 
used in construction of the Ercrev model, which has nitrate-to-chloride ion ratios above 0.50. The 
table shows the electrolyte composition (including chloride and nitrate ion molal concentrations), 
nitrate-to-chloride ion ratio, pH, temperature, the measured crevice repassivation potential, and 
the crevice repassivation potential model results at their minimum (-2 standard deviation (sd)) 
and maximum (+2 sd) values. The measured crevice repassivation potentials agree well with the 
model results although the crevice repassivation potential model results are generally lower than 
the measured values (i.e., the model is generally conservative). One exception to this 
observation is of note. The two measured crevice repassivation potentials in the 10 m CaCl2 + 
1.5 m Ca(NO3)2 solution at 100C are reported to be 13 and 18 mV SSC and the model predicts 
that the crevice repassivation to be between 50 and 94 mV SSC. The small difference between 
the model results and measured values is negligible for the purposes of modeling. 
It can also be seen from Table 6-8 that when the nitrate-to-chloride ion ratio exceeds 0.50, the 
crevice repassivation potential is generally not reported (two crevice repassivation potential 
measurements of 740 and 781 mV SSC shown in the table correspond to cross over of the 
reverse scan at potentials above the passive region). As discussed in Section 6.4.4.1, it is 
reasonable to use a value of +600 mV SSC when the crevice repassivation potential is not 
reported in tests such as these. The highest long-term corrosion potentials measured in the data 
used to construct the long-term corrosion potential model were about +415 mV SSC (measured 
in acidic SAW solutions with nitrate-to-chloride ion ratios of about 0.5). As can be seen from 
Figure 6-51, the effect of increasing pH is to decrease the measured long-term corrosion 
potential. Therefore, it is reasonable to expect that the long-term corrosion potential will never 
exceed about +415 mV SSC in the repository environment. From the data in Table 6-8, when 
the nitrate-to-chloride ion ratio is 0.50 or above at high temperatures (> 120C), and thus at high 
chloride and/or nitrate ion concentrations, the crevice repassivation potential is high enough to 
preclude localized corrosion initiation. 
ANL-EBS-MD-000003 REV 02 6-96 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
Table 6-8. High Temperature and Concentrated Solution Data and Model Results 
Source DTN Electrolyte Cl (m) NO3 (m) NO3/Cl Ratio pH a) T (C) Measured Ercrev 
(mV SSC) 
Model Ercrev 
-2 sd 
Model Ercrev 
+2 sd 
LL030409812251.054 [DIRS 164185] 6 M CaCl2 + 0.6 M Ca(NO3)2 16.323 1.64 0.1 5.34 120 37 -71 -11 
LL030409812251.054 [DIRS 164185] 7 M CaCl2 + 0.7 M Ca(NO3)2 20.815 2.073 0.1 5.34 130 32 -95 -14 
LL030409812251.054 [DIRS 164185] 7 M CaCl2 + 0.7 M Ca(NO3)2 20.815 2.073 0.1 5.34 130 24 -95 -14 
LL040402212251.084 [DIRS 170097] 10 m CaCl2 + 0.5 m Ca(NO3)2 20 1 0.05 5.34 100 -39 -93 -49 
LL040402212251.084 [DIRS 170097] 10 m CaCl2 + 0.5 m Ca(NO3)2 20 1 0.05 5.34 100 -41 -93 -49 
LL040402212251.084 [DIRS 170097] 12 m CaCl2 + 0.6 m Ca(NO3)2 24 1.2 0.05 5.34 130 -40 -168 -83 
LL040402212251.084 [DIRS 170097] 12 m CaCl2 + 0.6 m Ca(NO3)2 24 1.2 0.05 5.34 130 -39 -168 -83 
LL040402212251.084 [DIRS 170097] 18 m CaCl2 + 0.9 m Ca(NO3)2 36 1.8 0.05 5.34 160 11 -242 -81 
LL040402212251.084 [DIRS 170097] 18 m CaCl2 + 0.9 m Ca(NO3)2 36 1.8 0.05 5.34 160 7 -242 -81 
LL040402212251.084 [DIRS 170097] 10 m CaCl2 + 1.5 m Ca(NO3)2 20 3 0.15 5.34 100 13 50 94 
LL040402212251.084 [DIRS 170097] 10 m CaCl2 + 1.5 m Ca(NO3)2 20 3 0.15 5.34 100 18 50 94 
LL040402212251.084 [DIRS 170097] 12 m CaCl2 + 1.8 m Ca(NO3)2 24 3.6 0.15 5.34 130 13 -12 73 
LL040402212251.084 [DIRS 170097] 12 m CaCl2 + 1.8 m Ca(NO3)2 24 3.6 0.15 5.34 130 17 -12 73 
LL040402212251.084 [DIRS 170097] 18 m CaCl2 + 2.7 m Ca(NO3)2 36 5.4 0.15 5.34 160 239 -46 115 
LL040402212251.084 [DIRS 170097] 18 m CaCl2 + 2.7 m Ca(NO3)2 36 5.4 0.15 5.34 160 64 -46 115 
LL040402212251.084 [DIRS 170097] 10 m CaCl2 + 5 m Ca(NO3)2 20 10 0.5 5.34 100 600 b) 548 592 
LL040402212251.084 [DIRS 170097] 12 m CaCl2 + 6 m Ca(NO3)2 24 12 0.5 5.34 130 600 b) 534 619 
LL040402212251.084 [DIRS 170097] 12 m CaCl2 + 6 m Ca(NO3)2 24 12 0.5 5.34 130 600 b) 534 619 
LL040402212251.084 [DIRS 170097] 18 m CaCl2 + 9 m Ca(NO3)2 36 18 0.5 5.34 160 600 b) 642 803 
LL040402212251.084 [DIRS 170097] 18 m CaCl2 + 9 m Ca(NO3)2 36 18 0.5 5.34 160 600 b) 642 803 
LL040402212251.084 [DIRS 170097] 5 m Ca(NO3)2 + 5 m CaCl2 10 10 1 5.34 100 600 b) 587 621 
LL040402212251.084 [DIRS 170097] 5.8 m NaCl + 2.4 m NaNO3 + 18.2 m KNO3 5.8 20.6 3.55 5.34 100 600 b) 885 915 
LL040402212251.084 [DIRS 170097] 5.8 m NaCl + 2.4 m NaNO3 + 18.2 m KNO3 5.8 20.6 3.55 5.34 100 600 b) 885 915 
LL040402212251.084 [DIRS 170097] 5.8 m NaCl + 2.4 m NaNO3 + 18.2 m KNO3 5.8 20.6 3.55 5.34 115 600 b) 841 880 
LL040402212251.084 [DIRS 170097] 5.8 m NaCl + 2.4 m NaNO3 + 18.2 m KNO3 5.8 20.6 3.55 5.34 115 600 b) 841 880 
LL040402212251.084 [DIRS 170097] 15 m Ca(NO3)2 + 1.5 m CaCl2 3 30 10 5.34 125 600 b) 831 881 
LL040402212251.084 [DIRS 170097] 15 m Ca(NO3)2 + 1.5 m CaCl2 3 30 10 5.34 125 740 831 881 
LL040402212251.084 [DIRS 170097] 22.5 m Ca(NO3)2 + 0.225 m MgCl2 0.45 45 100 5.34 145 600 b) 766 903 
LL040402212251.084 [DIRS 170097] 22.5 m Ca(NO3)2 + 0.225 m MgCl2 0.45 45 100 5.34 145 781 766 903 
NOTES: a pH from a 5 M CaCl2 + 0.05 M Ca(NO3)2 solution (Sample ID JE0024, DTN: LL030502212251.063 [DIRS 163456]). 
b Ercrev value not reported. Value of +600 mV SSC used. Actual Ercrev may be higher. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-97 October 2004 
6.4.4.6.7 Implementation of the Waste Package Outer Barrier Localized Corrosion 
Initiation Model 
As discussed in the previous sections, the crevice repassivation potential model was constructed 
using data from pure chloride solutions and mixed chloride and nitrate solutions, including some 
data at high nitrate (up to 18 m) and chloride (up to 36 m) concentrations and high temperatures 
(up to 160C). However, the long-term corrosion potential model was constructed using data 
from relatively dilute (in terms of chloride and nitrate ion content) mixed ionic solutions 
(e.g., SAW and SCW), pure chloride solutions (up to about 12 m), and mixed chloride (up to 
about 13 m) and nitrate (up to about 2.6 m) solutions. The maximum temperature for any data 
point used in construction of the long-term corrosion potential model was 120C. The lack of 
measured long-term corrosion potential data in the high temperature (> 120C) regime indicates 
it would be prudent not to make use of the developed functional forms to predict localized 
corrosion initiation under these conditions. Like general corrosion, localized corrosion requires 
the presence of a liquid water film on the waste package surface. To implement the waste 
package outer barrier localized corrosion initiation model, the following criteria are applied in a 
stepwise fashion: 
1. If aqueous brine chemistry causes the initiation of localized corrosion, then localized 
corrosion continues to propagate regardless of changes in the bulk chemical exposure 
environment. This is a conservative modeling assumption made because no detailed 
model of the chemistry evolution of the crevice solution is available at this time. 
2. If the exposure temperature exceeds 160C and a water film is present on the waste 
package surface, then localized corrosion initiates. 
Localized corrosion initiated as a result of this criterion is reevaluated in accordance 
with Criterion 3 (below) when the exposure temperature drops below 160C. 
3. If the exposure temperature exceeds 120C but is less than or equal to 160C then, 
a) If the nitrate-to-chloride ion ratio is 0.5 (or greater), no localized corrosion will 
occur, or 
b) If the nitrate-to-chloride ion ratio is less than 0.5, then localized corrosion initiates 
and continues to propagate regardless of changes in the bulk chemical exposure 
environment (Criterion 1). 
4. If the exposure temperature is greater than or equal to 20C and less than or equal to 
120C then the empirical correlations for the long-term corrosion potential (Ecorr) and 
crevice repassivation potential (Ercrev) (Sections 6.4.4.3 and 6.4.4.5) are evaluated in 
accordance with the following implementation rules. If localized corrosion is 
determined to initiate, then localized corrosion continues to occur regardless of 
changes in the bulk chemical exposure environment (Criterion 1) 
a) If the nitrate-to-chloride ion ratio in the environment exceeds 0.5, 
then evaluate Ercrev and Ecorr at a nitrate-to-chloride ion ratio of 0.5. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-98 October 2004 
b) If the molality of chloride ion in the environment exceeds 36 molal, 
then evaluate Ercrev and Ecorr at a molality of chloride ion of 36 molal. 
If the molality of chloride ion is less than 0.001 molal, 
then evaluate Ercrev and Ecorr at a molality of chloride ion of 0.001 molal. 
c) If the molality of nitrate ion in the environment exceeds 18 molal, 
then evaluate Ercrev and Ecorr at a molality of nitrate ion of 18 molal. 
If the molality of nitrate ion is less than 0.001 molal, 
then Ercrev = o
rcrev E (i.e., the crevice repassivation potential in the absence 
of nitrate ions) and evaluate Ecorr at a molality of nitrate ion of 0.001 
molal. 
d) If the pH in the environment exceeds 10.9, 
then evaluate Ercrev and Ecorr at a pH of 10.9. 
If the pH in the environment is less than 2.8, 
then initiate localized corrosion. 
The chemical limits specified in Criterion 4 are conservative. Limiting the chloride-to-nitrate 
ratio used in evaluation of the model to 0.5 is conservative because Ercrev increases markedly with 
nitrate ion concentration, at a given chloride ion concentration, pH and temperature, while Ecorr is 
relatively insensitive to nitrate ion concentration (at higher nitrate ion concentrations) (e.g., 
Figure 6-64). Limiting the chloride-to-nitrate ratio to 0.5 limits the beneficial effect of nitrate 
concentration in the localized corrosion initiation model as does limiting the nitrate ion 
concentration to 18 molal (consistent with the highest nitrate ion concentration at which Ercrev 
data was obtained). Both Ercrev and Ecorr decrease with chloride ion concentration, at a given 
nitrate ion concentration, temperature, and pH, although Ecorr decreases at a faster rate than Ercrev 
at higher chloride ion concentrations (e.g., Figure 6-59). Therefore, limiting the chloride ion 
concentration to 36 molal (consistent with the highest chloride ion concentration at which Ercrev 
data was obtained) is conservative for determination of localized corrosion initiation 
(i.e., .E = Ercrev - Ecorr = 0). At lower chloride ion concentrations, Ercrev generally decreases at a 
faster rate than Ecorr; therefore, the lower bound chloride ion concentration is limited to 
0.001 molal. Also, the functional forms for Ecorr (Equation 6-36) and - . 3 NO 
rcrev E (Equation 6-34) 
contain nitrate-to-chloride ratios that increase at unrealistically high rates at low (< 0.001 molal) 
chloride ion concentrations. It is necessary to impose a lower limit (0.001 molal) to the nitrate 
ion concentration as the functional form for Ecorr involves a logarithm of nitrate ion 
concentration which is undefined (approaches -8) at zero nitrate ion concentration. The use of a 
lower limit nitrate ion concentration is conservative for evaluating Ercrev (i.e., - . 3 NO 
rcrev E is always 
positive in Equation 6-31). Ercrev increases with increasing pH at constant temperature and 
nitrate and chloride ion concentrations, and Ecorr decreases with increasing pH at constant 
temperature and nitrate and chloride ion concentrations (e.g., Figure 6-62). It is conservative to 
use an upper limit on pH of 10.9 (consistent with the highest pH at which Ecorr data was 
obtained), because Ercrev is restricted from increasing further and Ecorr from decreasing further at 
higher pH values). Similarly, it is conservative to initiate localized corrosion at the lower 
limiting pH of 2.8 (consistent with the lowest pH at which Ecorr data was obtained). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-99 October 2004 
6.4.4.7 Localized Corrosion Penetration Rate Model 
If the corrosion potential of the WPOB exceeds the critical potential, the WPOB is considered to 
be subject to localized (crevice) corrosion, and penetration of the barrier by localized corrosion is 
modeled. Due to the outstanding corrosion resistance of Alloy 22, very little data exists for 
localized corrosion penetration rates under repository-relevant exposure conditions. 
A reasonable lower bound for the localized corrosion propagation rate of Alloy 22 would be its 
average corrosion rate in a highly aggressive 10% ferric chloride crevice corrosion test solution. 
According to vendor data (Haynes International 1997 [DIRS 100897], p. 8), the average 
corrosion rate of Alloy 22 in a 10% ferric chloride solution at 75C is 0.5 mils/yr or 12.7 m/yr. 
A reasonable upper bound for Alloy 22 localized corrosion penetration rates would be corrosion 
rates in concentrated HCl solutions at elevated temperatures. Alloy 22 corrosion rates between 5 
and 50 mils/yr (i.e., between 127 and 1,270 m/yr) (Haynes International 1997 [DIRS 100896], 
p. 12) were obtained under these conditions. Although higher corrosion rates are shown in the 
cited reference, the chosen rates are high enough to adequately represent the localized corrosion 
penetration rate for modeling purposes. A 20-mm-thick Alloy 22 barrier would be penetrated in 
16 to 160 years using the chosen penetration rates (i.e., these rates are high enough for their 
intended purpose). Generally, the true localized corrosion penetration rates in local areas may 
be higher than those measured by weight loss. However, the literature data mentioned above 
were from short-term tests, and are, therefore, conservative for use in long-term localized 
corrosion degradation analysis because the rate of localized corrosion penetration tends to 
decrease with time (Section 6.4.4.8.2). 
Based on these data, the localized corrosion penetration rates for the WPOB are modeled in a 
range from 12.7 to 1,270 m/yr with the median value of 127 m/yr, as shown in Table 6-9. 
A log-uniform distribution between the bounds was chosen for the localized corrosion 
penetration rate. The basis for this selection is that the penetration rate values from the literature 
span three orders of magnitude, and the percentiles provided are consistent with a log-uniform 
distribution. This distribution is based on data that bounds those extreme penetration rates found 
in the literature and are a highly conservative representation of localized corrosion rates of 
Alloy 22 for the exposure conditions expected in the postclosure repository. The entire variance 
in the penetration rate is due to uncertainty. 
Table 6-9. Distribution of Localized Corrosion Rates for Alloy 22 
Percentile Localized Corrosion Rate (m/yr) 
0th 12.7 
50th 127.0 
100th 1,270.0 
Output DTN: MO0409MWDULCMW.000. 
6.4.4.8 Alternative Conceptual Models for Localized Corrosion 
Alternative conceptual models (ACMs) are based on modeling assumptions and simplifications 
different from those employed in the base-case model. An important reason for considering 
ACMs is to help build confidence that changes in modeling assumptions or simplifications will 
not change conclusions regarding subsystem and total system performance. Conceptual model 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-100 October 2004 
uncertainty results from sparse observational data and a lack of available information to 
corroborate or refute plausible alternative interpretations of the subsystem and the processes 
occurring within the subsystem. This section discusses the ACMs for the localized corrosion 
models of the waste package outer barrier (WPOB). 
6.4.4.8.1 Localized Corrosion Susceptibility of the Waste Package Outer Barrier 
Localized corrosion of the WPOB is modeled with two model components: an initiation model 
and a propagation model. Localized corrosion of the WPOB occurs when the open-circuit 
corrosion potential (Ecorr) is equal to or greater than a critical potential (the crevice repassivation 
potential (Ercrev) in this report), that is, .E (=Ercrev - Ecorr) = 0. This conceptual model of 
localized corrosion initiation is widely accepted by the corrosion community and has been 
published extensively (Bhni 2000 [DIRS 164137], Section B; Dunn et al. 2000 [DIRS 164495]; 
Dunn et al. 2003 [DIRS 164138]; Frankel 1998 [DIRS 162216]; Frankel 2002 [DIRS 164140]; 
Frankel and Kelly 2002 [DIRS 164141]; Beavers et al. 2002 [DIRS 158781], Section 8.3). 
Exposure conditions in the repository will evolve with time, making it necessary to know Ecorr 
and Ercrev as a function of this evolution. This requires that a database of Ercrev values covering 
this range of conditions, plus a model for the evolution of Ecorr with exposure time are required. 
An alternative parameter that can be used to determine susceptibility to localized corrosion is 
temperature. The evolution of waste package temperature with time can be calculated with 
reasonable certainty. This evolution, coupled with knowledge of the critical temperature for the 
initiation of localized corrosion (pitting/crevice corrosion) can then be used to determine when 
these processes may occur. 
The use of critical temperatures in this manner was well documented (Frankel 1998 
[DIRS 162216]), and values of critical pitting temperature (CPT) and critical crevice corrosion 
temperature (CCT) have been measured for a series of alloys, including Alloy 22, in relatively 
pure concentrated chloride solutions (i.e., high salinity, [Cl-] = 24,300 g/g, and a high [Cl-] to 
[SO4
2-] ratio) (Haynes International 1997 [DIRS 100897], p. 9; McGuire et al. 1998 
[DIRS 152193], Section 5.1.2). However, the test conditions are not directly relevant to the 
potential environments on the waste package surface. Under these highly corrosive conditions, 
the CCT for Alloy 22 was measured to be 102 C, and for Alloy 276 to be 80 C. The CPT for 
Alloy 22 was greater than 150 C, and that for Alloy 276 was 150 C. 
The critical temperature-based model is not considered in the TSPA-LA because it does not 
account for the effects of electrochemical characteristics of the solution contacting the metal, 
particularly those of important corrosion inhibiting anions such as nitrate and sulfate ions present 
in the groundwater at the repository. 
6.4.4.8.2 Time-Dependent Growth Law for Localized Corrosion 
The base-case model assumes that, when localized corrosion of the WPOB occurs, it propagates 
at a (time-independent) constant rate (Assumption 5.4). This assumption is highly conservative 
because it is known that the localized corrosion rate decreases with time (CRWMS M&O 1998 
[DIRS 100349], Table 3-2; Hunkeler and Boehni 1983 [DIRS 162221]; McGuire et al. 1998 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-101 October 2004 
[DIRS 152193], Section 5.2.8, EPRI 2002 [DIRS 158069], Section 5.3.1; Frankel 1998 
[DIRS 162216]; Newman and Franz 1984 [DIRS 162250]). 
An alternative conceptual model for the localized corrosion penetration is a time-dependent 
growth law. The growth law model can be developed based on a combination of electrochemical 
and corrosion exposure measurements. A simple pitting model based on hemispherical pit 
growth yields a penetration law of the form (CRWMS M&O 1998 [DIRS 100349], Table 3-2; 
Hunkeler and Boehni 1983 [DIRS 162221]; McGuire et al. 1998 [DIRS 152193], Section 5.2.8) 
n t k D  = (Eq. 6-38) 
where D is the depth of penetration, t is time, and k is a growth constant. The growth constant 
will be dependent on the properties of the material, particularly its susceptibility to anodic 
dissolution in the acidic environment prevailing in a propagating localized corrosion site. The 
time exponent, n, would be about 0.5 for both diffusion-controlled (i.e., diffusion of metal ions 
out of the pit) and ohmically controlled (i.e., rate determined by the ohmic potential drop which 
develops in the electrolyte in the pit) pit growth (McGuire et al. 1998 [DIRS 152193], 
Section 5.2.8; Vetter and Strehblow 1974 [DIRS 162245]). The above model was used in a 
separate analysis for the repository by the Electric Power Research Institute (EPRI) (EPRI 2002 
[DIRS 158069], Section 5.3.1). 
The significance of this pit penetration law has been discussed by Frankel (1998 [DIRS 162216]) 
and leads to a pit growth current density (i) proportional to the inverse square root of time (i.e., i 
. t-1/2) in potentiostatic electrochemical experiments. Hunkeler and Boehni (1983 
[DIRS 162221]) have shown that this growth law is obeyed for both the pitting and crevice 
corrosion of stainless steels. Newman and Franz (1984 [DIRS 162250]) have also observed a 
similar relationship for stainless steel. 
When trying to adapt such a law for practical applications, two main problems arise: 
(1) insufficient penetration rate data are available, especially for relatively new materials such as 
Alloy 22, to determine values of k and n; and (2) the factors that control the form of this 
apparently simple growth law are complex and, at best, only qualitatively understood. In order to 
determine values of k and n, it is necessary to employ short-term experiments in which the pit 
growth process is accelerated electrochemically. In these experiments, those features of the 
propagation process that enhance growth (the development of critical chemistry; the evolution of 
pit geometry) are dominant. However, it is necessary to predict penetration behavior after long 
periods of exposure, when those factors that limit growth (IR drop, loss of critical chemistry, 
evolution of metallurgical factors, polarization of cathodic processes) are more important. 
The literature data available for less corrosion-resistant materials (e.g., iron, copper, Ti Grade 2) 
(Hunkeler and Boehni 1983 [DIRS 162221]; Marsh et al. 1991 [DIRS 162234]; Mughabghab 
and Sullivan 1989 [DIRS 162235]; Sharland et al. 1991 [DIRS 162238]; and Ishikawa et al. 1991 
[DIRS 162222]) clearly show that a penetration growth law of the form of Equation 6-38 is 
appropriate, and that a value of n = 0.5, the theoretically predicted value, is justifiable. A key 
point with the materials discussed above (e.g., iron, carbon steel, copper and Titanium Grade 2) 
is that they are materials that would be expected to undergo rapid propagation. Providing it is not 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-102 October 2004 
stifled by the accumulation of corrosion product deposits or slow cathodic kinetics, propagation 
would be limited only by diffusive or ohmic effects, leading to a value of n approaching 0.5. 
By contrast, for highly corrosion-resistant materials such as Alloy 22 designed to resist localized 
corrosion, additional metallurgical features will be important in determining the value of n. One 
example of such a metallurgical influence that is pertinent to the case of Alloy 22 is the ability of 
molybdenum to decrease the pitting current densities in stainless steels, possibly by reducing the 
active dissolution rate within the pit (Frankel 1998 [DIRS 162216]; and Newman 1985 
[DIRS 162251]). This prevents the maintenance of the critical pit or crevice chemistry to sustain 
propagation, leading to repassivation. Again, the n value in the growth law in Equation 6-38 
would effectively tend to zero. This is supported by the observation of Kehler et al. (2001 
[DIRS 162231]), who showed that the depth of crevice penetration for Alloy 22 
electrochemically driven in extremely saline (5 mol/L LiCl) solutions at 85C was limited to less 
than 100 m. The adoption of such a value considers that metallurgical features, such as the 
influence of molybdenum on pit/crevice propagation will suppress penetration. 
Localized corrosion rate data are needed to obtain a value for k. The only presently available 
source of crevice corrosion rate data is that published by Haynes International (1997 
[DIRS 100897]) and summarized in Table 22 of Gdowski (1991 [DIRS 100859]). These data 
were recorded in 10 weight percent FeCl3 (i.e., under extremely aggressive oxidizing conditions). 
The localized corrosion growth law model of the form of Equation 6-38 is not used in the 
TSPA-LA because of lack of data to obtain the values of the model parameters, n and k for 
Alloy 22 for the exposure conditions relevant to the repository. The base-case model (timeindependent 
constant penetration rate model) is much more conservative than the growth law 
model. The base-case model should bound the penetration rate range by localized corrosion of 
the WPOB when it occurs. 
6.4.5 Effect of Microbial Activity on Corrosion 
Microbially influenced corrosion (MIC) is the contribution to the corrosion of a metal or alloy 
due to the presence or activity, or both, of microorganisms. MIC most often occurs due to the 
increase in anodic or cathodic reactions due to the direct impact of microorganisms on the alloy 
or by indirect chemical effects on the surrounding solution. Microorganisms can affect the 
corrosion behavior of an alloy either by acting directly on the metal or through their metabolic 
products. For example, some types of aerobic bacteria may produce sulfuric acid by oxidizing 
reduced forms of sulfur (elemental, sulfide, sulfite), and certain fungi transform organic matter 
into organic acids (Fontana 1986 [DIRS 100890], Section 8-10). Bacterial isolates from Yucca 
Mountain have been shown to be capable of iron oxidation, acid production, sulfate reduction 
and slime generation (Lian et al. 1999 [DIRS 110238]). However, acid production from sulfide 
oxidation in the repository is unlikely because the drift environment will remain oxic over the 
regulatory compliance period (BSC 2004 [DIRS 169991], Section 7.1). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-103 October 2004 
In Evaluation of the Impact of Microbial Activities on Drift Chemistry (BSC 2004 
[DIRS 169991], Section 7.1), based on different nutritional requirements, microorganisms are 
categorized into one of two groups: 
1) Heterotrophs, which use organic carbon compounds as their carbon and energy 
source, and 
2) Autotrophs, which derive their energy from the oxidation of inorganic compounds 
and cell carbon from CO2. 
In the repository, heterotrophic microbial activities will be limited by the lack of a significant 
organic carbon supply; autotrophic microbial activities will be limited by the lack of available 
inorganic electron donors in the oxic repository environment (BSC 2004 [DIRS 169991], 
Section 7.1). 
The following environmental factors will severely limit microbial activities in the repository 
(BSC 2004 [DIRS 169991], Section 7.1): 
 The in-drift temperatures during the thermal pulse created by radioactive decay will 
exceed the temperature tolerance of all known microbes for a significant portion of the 
repository time, thus exerting a sterilization effect on microorganisms. 
 An oxic environment will prevail in the repository over the growth-permissive period 
and, therefore, prevent the generation and accumulation of reduced inorganic species 
that are the prerequisite for autotrophic metabolism. 
 Microbial incubation experiments have demonstrated that water availability is the 
primary limiting factor for microbial growth in the repository. The relative humidity 
and the liquid-water saturation degree in the repository are predicted to be low, thus 
further limiting microbial activities. 
 Evaporation of seepage waters in the low relative humidity environment will result in 
brine solutions with ionic strengths higher than 10 molar, which is an environment in 
which only a few halophiles may be able to survive. 
 Phosphate and organic carbon are important limiting factors for microbial growth in the 
repository. The extremely low organic carbon supply in the repository will limit 
heterotrophic microbial activities. 
 Because of elevated temperatures, radiation fields, low humidity, and low nutrient 
supplies, the formation of biofilms in the drift is unlikely. 
Due to the aforementioned environmental constraints, microbial activity in the repository will be 
limited, and its impacts on drift chemistry will be insignificant (BSC 2004 [DIRS 169991], 
Section 7.1). Evaluation of the Impact of Microbial Activities on Drift Chemistry (BSC 2004 
[DIRS 169991], Section 7.1) also states that: 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-104 October 2004 
 Yucca Mountain groundwater contains only a trace concentration of organic carbon, 
which is negligible compared to the total carbonate concentration in the solution. 
Furthermore, an autotrophic microbial reaction, if it occurs, will not generate CO2, 
because it is a CO2-fixation process, and the accumulated biomass will probably be 
recycled back to CO2, resulting in zero CO2 accumulation or depletion. Even if all the 
organic carbon were converted to carbon dioxide, the perturbation to the water chemistry 
is negligible. Therefore, the impact of microbial activity on water chemistry (pH and 
total CO2) will be negligible. 
 In an oligotrophic environment such as the repository, microbial activities are limited, 
and the concentrations of the microbially generated low molecular weight organic acids 
are expected to be very low. The complexation effect of these organic acids on 
radionuclide dissolution is negligible. 
 Since an oxic environment will prevail in the repository, actinide precipitation due to 
reduction from higher to lower valence states will be unlikely. For the same reason, 
microbial activity will not reductively dissolve Fe(III) oxides generated from oxic metal 
corrosion and, therefore, will not change the availability of sorption sites for 
radionuclides in the repository. Other biotransformation processes (such as dissolution 
due to oxidation reactions, production of sequestering agents, and biosorption) may 
occur, but their impacts on radionuclide mobility will be insignificant, due to a low 
microbial activity in the repository. 
 Due to the oxic environment, denitrification is inhibited. Microbial consumption of 
nitrate will be unlikely. 
 A long-distance biocolloidal transport is unlikely in a subsurface environment, 
especially in an unsaturated zone. Field measurements indicate that a majority of 
microbial cells are attached to solid matrix. Through biosorption and bioaccumulation, 
microbes actually tend to immobilize radionuclides in subsurface systems. It is expected 
that biocolloids generated in the drift will be filtered out and readsorbed within the 
invert or the unsaturated zone. 
Based on this discussion, the effects of MIC on waste package degradation will be minimal (BSC 
2004 [DIRS 169991], Section 7.1). Specifically, the following factors will limit, if not 
completely prevent, microbially influenced corrosion (BSC 2004 [DIRS 169991], Section 7.1): 
 Oxic environments will prevail in the repository over the regulatory time period. 
Therefore, sulfate reduction  an anaerobic reaction pathway generally considered to be 
responsible for MIC  will be unlikely to occur. For the same reason, microbial 
oxidation of sulfide will also be unlikely due to lack of reduced sulfur species in the 
repository. 
 The repository conditions of low relative humidity, elevated temperature, high radiation 
dose, and limited nutrient supplies all together will prevent the formation of biofilms, 
which are generally required for MIC. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-105 October 2004 
Although microbes can be active at relative humidity as low as 75%, most microbes can thrive 
only when relative humidity is above 90% (BSC 2004 [DIRS 169991], Section 7.1). In the TSPA 
calculations, a threshold for microbially influenced corrosion of 90% relative humidity is used 
(BSC 2004 [DIRS 169991], Section 7.1). This choice for the threshold for microbially influenced 
corrosion likely leads to an overestimate of MIC effect, because the other factors such as 
elevated temperature, high radiation dose, and limited nutrient supplies will also limit microbial 
activity, for which microbes will require even higher relative humidity to maintain their active 
metabolism (BSC 2004 [DIRS 169991], Section 7.1). On this basis, the MIC factor is applied to 
the WPOB general corrosion rate only when the relative humidity at the WPOB surface is 
greater than or equal to 90 percent (i.e., the activity of water is greater than or equal to 0.90). 
Results of a recent study on the biofilms formation on Alloy 22 coupons by the microbes 
obtained from the repository tuff rocks (Else et al. 2003 [DIRS 168172]) indicate that the above 
RH threshold for MIC without considering the effect of temperature is highly conservative. The 
study showed that 100 % RH and 30C were the optimal conditions for bacterial attachment and 
biofilm formation on Alloy 22 coupon surfaces. At decreased RH values, ranging from 32% to 
84% at 30C, culturable counts were below or near the level of detection for all metal types 
studied. It was shown that as temperature increases (to 60C or 70C) or RH decreases to below 
100%, biofilm formation on Alloy 22 coupon surfaces was impeded. The study concluded that 
the boundary conditions for the microbe colonization on the metal surfaces required 100% RH 
and 30C for even minimal biofilms production (Else et al. 2003 [DIRS 168172]). 
Environmental factors that affect levels of bacterial growth include temperature and radiation. 
These factors, however, are closely coupled to RH; as temperature and radiation decrease in the 
repository, RH is predicted to increase. At the same time, while there are some types of 
microorganisms that can survive elevated temperatures (= 120C) and high-radiation doses, if 
there is no available water, then microbial activity is completely prevented. Thus, because water 
availability is the primary limiting factor and this factor is coupled to other less critical limiting 
factors, water availability (as expressed by RH) was used as the primary gauge of microbial 
activity. 
It has been observed that nickel-based alloys such as Alloy 22 are highly resistant to microbially 
influenced corrosion (Lian et al. 1999 [DIRS 110238]). Furthermore, microbial growth in the 
repository will be limited by the availability of nutrients such as organic carbon, nitrogen, or 
phosphorous (BSC 2004 [DIRS 169991], Section 7.1). There are no standard tests designed 
specifically to investigate the susceptibility of an engineering alloy to MIC (Stoecker 1987 
[DIRS 162243]). One commonly used method to evaluate the effect of MIC is to test the alloy 
of interest in-situ (in the field) using the same variables as for the intended application. However, 
testing in the laboratory with live organisms can provide more controlled conditions of various 
environmental variables, and sterile controls can be incorporated to better assess MIC-specific 
effects (Horn and Jones 2002 [DIRS 162220]). The latter approach was used to evaluate the 
effects of microbiological processes on general corrosion of the WPOB. 
The Project has conducted MIC testing in which Alloy 22 coupons were incubated with sterile or 
nonsterilized Yucca Mountain rock in simulated concentrated (10) groundwater for almost 
5 years (DTN: LL040303612251.078 [DIRS 170221]). Scanning Electron Microscope (SEM) 
images of unexposed, sterile control, and nonsterile samples are shown in Figure 6-67. Alloy 22 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-106 October 2004 
samples exposed to microbial environments showed submicron-sized degradation after 
almost 5 years of exposure; similar degradation was not seen in sterile controls after 43 months 
of exposure. Although the surface morphology differs between sterile and nonsterile samples, the 
submicron-sized degradation morphology does not have the macroscopic appearance of pitting 
corrosion, which tends to result in larger pit diameters (e.g., Smailos 1993 [DIRS 168164], 
Figures 2 and 3). Note that grinding marks are evident on both sterile and nonsterile sample 
surfaces even after about 5 years of exposure. Such a corrosion surface morphology would 
better be described as enhanced general corrosion especially at higher submicron-sized 
degradation densities. 
For general corrosion of the WPOB, the effect of MIC can be described as follows; 
MIC st MIC f CR CR  = (Eq. 6-39) 
where CRMIC is the general corrosion rate in the presence of microorganisms, CRst is the general 
corrosion rate of the alloy in the absence of microorganisms, and fMIC is the MIC factor. If fMIC is 
greater than one, there is an enhancement of the corrosion rate of the alloy as a consequence of 
the presence or activity of microorganisms. 
Lian et al. (1999 [DIRS 110238]) has shown that MIC can enhance corrosion rates of Alloy 22 
by a factor of two. Measurements for Alloy 22 are shown in Table 6-10. This study 
used 12 strains of Yucca Mountain bacteria, including acid, slime, and sulfide producers, as well 
as iron-oxidizing bacteria. The growth medium was supplemented with 0.5% glucose and 0.75% 
protease peptone in 100x concentrated simulated J-13 well water Lian et al. (1999 
[DIRS 110238]). The MIC factor fMIC is calculated as the ratio of corrosion rates (microbes to 
sterile) from the table. The value of fMIC for Alloy 22 in sterile media is one (fMIC = 1), whereas 
the value of fMIC for Alloy 22 in inoculated media is larger (fMIC = 2). The MIC factor, fMIC, is 
uniformly distributed between 1 and 2, and the variance of this distribution is entirely due to 
uncertainty. 
Table 6-10. Alterations in Corrosion Rates and Potentials of Mill-Annealed Alloy 22 Associated with 
Microbial Degradation at Room Temperature 
Corrosion Potential Ecorr (VSCE) 
Tested Sample Initial Condition 
Average Corrosion Rate 
(m/yr) Initial Endpoint 
Alloy 22 + Yucca Mountain Microbes 0.022 -0.440 -0.252 
Sterile Alloy 22 0.011 -0.260 -0.200 
Source: DTN: LL991203505924.094 [DIRS 138343]. 
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ANL-EBS-MD-000003 REV 02 6-107 October 2004 
Source: DTN: LL040303612251.078 [DIRS 170221]. 
NOTE: Coupons were (a) unexposed, (b) exposed for 43 months in a sterile microcosm, and (c) exposed for 
57 months in a nonsterile microcosm. 
Figure 6-67. Comparison of Scanning Electron MicroscopyImaged Alloy 22 Coupons (8,000 
Magnification) 
Electrochemical corrosion rate results were also obtained on welded Alloy 22 coupons exposed 
to 100 J-13 well water plus 0.1 percent glucose at ambient temperature 
(DTN: LL040402912251.085 [DIRS 170222]). The testing was carried out in both Yucca 
Mountain microorganism-inoculated and sterile environments using the techniques of ASTM G 
59-97 (1998 [DIRS 163907]), Standard Test Method for Conducting Potentiodynamic 
Polarization Resistance Measurements, as performed on base metal. The tests were run for 70 to 
125 days at room temperature. Testing at room temperature for MIC effects is conservative 
because the viability of the microbes is not compromised due to elevated temperatures (Else et 
al. 2003 [DIRS 168172]). The results show that the corrosion rates obtained for welded coupons 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-108 October 2004 
in nonsterile environments were only slightly higher than those in sterile environments (Figure 
6-68) and consistent with the corrosion enhancement factor obtained from the nonwelded coupon 
data shown in Table 6-10. The data also show that the corrosion rates for welded coupons are 
essentially the same as those for nonwelded coupons. 
Source: DTN: LL040402912251.085 [DIRS 170222]. 
Figure 6-68. Corrosion Rates Determined by Polarization Resistance Testing of Welded Alloy 22 
Coupons 
Not all areas are equivalent on any given waste package with respect to bacterial colonization. It 
is well documented that bacteria preferentially colonize on weldments, and heat-affected zones 
(Borenstein and White 1989 [DIRS 128141]; Walsh 1999 [DIRS 138928]; Enos and Taylor 1996 
[DIRS 128233]). Conservatively, the MIC factor is applied to the entire waste package surface 
area. The treatment is conservative because the effects of MIC are not being applied only to the 
welded regions where bacteria preferentially colonize. 
Determination of a critical mass of total bacteria required to cause MIC is not an issue that needs 
to be addressed in the MIC model. Bacterial densities in Yucca Mountain rock have been 
determined to be on the order of 104 to 105 cells/gm of rock (BSC 2004 [DIRS 169991], 
Section 6.3). In absolute terms, this is almost certainly above the threshold required to cause 
MIC. A more germane concern is the types of bacteria present, their abundance, and how their 
relative numbers are affected when water is available for growth. Corrosion rates will be 
affected (at least on some waste package materials) for example, if organic acid producers outcompete 
sulfate reducers or inorganic acid producers for available nutrients when water is 
sufficient to support growth. No data are currently available regarding the composition of the 
bacterial community over the changing environmental conditions anticipated during repository 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-109 October 2004 
evolution. Instead, this issue has been addressed in the current model by determining overall 
corrosion rates under a standardized set of conditions, in the presence and absence of a defined 
set of characterized Yucca Mountain bacteria. 
6.4.6 Effect of Aging and Phase Instability on Corrosion 
As specified in the waste package design and fabrication specification (Plinski 2001 
[DIRS 156800], Section 8.1), the WPOB base metal and all fabrication welds (not including the 
welds for the closure lids) are fully annealed before the waste packages are loaded with waste. 
Analysis documented in Aging and Phase Stability of Waste Package Outer Barrier (BSC 2004 
[DIRS 169983], Section 8) has shown that phase instabilities are not expected in Alloy 22 base 
metal and welded material due to the thermal hydrologic exposure profiles in the repository. 
Nonthermal stress mitigation processes, currently planned for the outer lid closure weld, may 
introduce cold work into the material. Angeliu (2001 [DIRS 165442]) observed that unmitigated 
Stainless Steel Type 316NG weldments can contain up to 20 percent cold work due to weld 
shrinkage and differential thermal expansion. Given that the phase instability analysis included 
welded samples, the effects of cold work have been included in the analysis as well. 
Project data show that the corrosion properties of aged welds are comparable to those of unaged 
welds. In order to analyze the effect of thermal aging on corrosion of Alloy 22, three 
metallurgical conditions of Alloy 22 were studied at the LTCTF using the multiple crevice 
assembly (MCA) samples: mill annealed, as-welded, and as-welded plus thermally aged 
(at 700C for 173 hours). The samples were tested in 5 M CaCl2 and 5 M CaCl2 + 0.5 M 
Ca(NO3)2 solutions with the test temperatures up to 120C. As described in Appendix I, after 
being immersed in the test solution in an open-circuit condition for 24 hours, the polarization 
resistance of the samples was measured. 
Comparison of the calculated corrosion rates of the mill-annealed (MA), as-welded (ASW), and 
as-welded plus thermally aged samples are shown in Figure 6-69 for 5 M CaCl2 solutions and 
Figure 6-70 for 5 M CaCl2 + 0.5 M Ca(NO3)2 solutions. The corrosion rate data are listed in 
Appendix IV. As discussed earlier (Sections 4.1.1.4 and 6.4.3.4), corrosion rates from 
polarization resistance measurements are only for comparative analysis of the effect of thermal 
aging on corrosion rates; the tests are not intended to be used to obtain absolute values of the 
corrosion rate. The absolute values of the general corrosion rates of Alloy 22 are determined 
from weight-loss measurements as discussed in Section 6.4.3.4. The mill-annealed MCA 
samples in 5 M CaCl2 solutions at differing temperatures were considered as the baseline 
condition for the analysis. The baseline condition rates were compared with those of the ASW 
and ASW plus thermally aged MCA samples tested in the same electrolyte solution condition. 
A data trend-line was drawn for the baseline condition data for an easier comparison with the 
ASW and ASW plus thermally aged sample data. The comparison shown in Figure 6-69 clearly 
shows that there is no significant enhancement of the corrosion rate due to welding or thermal 
aging of the welded samples for the tested conditions. 
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ANL-EBS-MD-000003 REV 02 6-110 October 2004 
Corrosion Rate Comparison of MA, ASW, and ASW+Aged Samples without Nitrate 
Corrosion Rates from Polarization Resistance Data 
0 
2000 
4000 
6000 
8000 
10000 
12000 
14000 
16000 
18000 
20000 
20 40 60 80 100 120 140 
Temperature (C) 
Corrosion Rate (nm/year) 
MA MCA 5M CaCl2 
ASW MCA 5M CaCl2 
ASW+Aged MCA 5M CaCl2 
Trendline for MA MCA 5M CaCl2 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-69. Comparison of Corrosion Rates from Polarization Resistance Measurements of Mill- 
Annealed (MA), As-Welded (ASW), and As-Welded Plus Aged Alloy 22 MCA Samples in 
5 M CaCl2 Brines at Varying Temperatures 
A similar comparison is made for the corrosion rates measured in 5 M CaCl2 + 0.5 M Ca(NO3)2 
solutions, as shown in Figure 6-70. As for the 5 M CaCl2 solution case, the MA MCA samples 
at differing temperatures were considered as the baseline condition, and a data trend-line was 
drawn for the baseline condition data for an easier comparison. The comparison in Figure 6-70 
again clearly shows no significant enhancement of the corrosion rate due to welding or thermal 
aging of the welded samples. It is also noted that the corrosion rates of all three type samples 
(MA, ASW, and ASW plus thermally aged) were reduced by a factor of 3 to 4 in the nitrate 
containing solutions, compared to those in 5 M CaCl2 solutions. The beneficial effects of 
inhibiting nitrate ions are clearly demonstrated by these results. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 6-111 October 2004 
Corrosion Rate Comparison of MA, ASW, and ASW+Aged Samples with Nitrate 
Corrosion Rates from Polarization Resistance Data 
0 
2000 
4000 
6000 
8000 
10000 
12000 
14000 
16000 
18000 
20000 
20 40 60 80 100 120 140 
Temperature (C) 
Corrosion Rate (nm/year) 
MA MCA 5M CaCl2 + 0.5M 
Ca(NO3)2 
ASW MCA 5M CaCl2 + 0.5M 
Ca(NO)3)2 
ASW+Aged MCA 5M CaCl2 + 
0.5M Ca(NO3)2 
Trendline for MA MCA 5M CaCl2 
+ 0.5M Ca(NO3)2 
Output DTN: MO0409MWDUGCMW.000. 
Figure 6-70. Comparison of Corrosion Rates from Polarization Resistance Measurements of Mill- 
Annealed (MA), As-Welded (ASW), and As-Welded Plus Aged Alloy 22 MCA Samples in 
5 M CaCl2 + 0.5 M Ca(NO3)2 Brines at Varying Temperatures 
Investigations in the published literature are consistent with the above analyses. Comparisons of 
the anodic passive current densities of as-welded Alloy 22 samples to those of base metal 
samples and have shown no significant effect of the presence of welds on the passive corrosion 
behavior of the alloy (Brossia et al. 2001 [DIRS 159836], Section 3.2.1.3, Figure 3-13). 
Rebak et al. (2002 [DIRS 162237]) investigated the effects of high-temperature aging on the 
corrosion resistance of Alloy 22 in SCW and SAW concentrated multi-ionic solutions (samples 
aged in air at 700C for 10 and 173 hours) and aggressive acidic solutions (50 percent sulfuric 
acid + 42 g/L ferric sulfate solutions and concentrated hydrochloric acid solutions; samples aged 
for a variety of times (up to 3,000 hours) and at temperatures between 482C and 760C). The 
investigators found that precipitation of secondary phases at grain boundaries (due to the aging 
treatments) was detrimental to the corrosion resistance of Alloy 22 in aggressive acidic solutions, 
but did not significantly affect the corrosion resistance in concentrated multi-ionic solutions, 
which are more relevant to the repository exposure conditions (Rebak et al. 2002 
[DIRS 162237]). 
Based on the above analysis and insignificant aging and phase instability processes under the 
thermal conditions expected in the repository (BSC 2004 [DIRS 169983], Section 8), the 
corrosion performance of the WPOB is not expected to be affected by the aging and phase 
instability in the repository. Hence, thermal aging and phase instability of the WPOB was not 
included in TSPA-LA. 
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INTENTIONALLY LEFT BLANK 
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ANL-EBS-MD-000003 REV 02 7-1 October 2004 
7. VALIDATION 
Models described in this report are expected to adequately predict general and localized 
corrosion processes of the WPOB under the exposure conditions expected in the repository for a 
period of at least 10,000 years. This long time of application makes it difficult to validate these 
models in the usual way (i.e., by comparison of model predicted values with those observed 
experimentally for the whole range of time) (ASTM C 1174-97 1998 [DIRS 105725], 
Sections 19.3 and 20.4). Consequently, by validating the input parameter values used and 
comparing these parameters and model predictions to available peer-reviewed and qualified 
Project data, these models were validated. As required by AP-2.27Q and stated in the technical 
work plan (TWP) for this activity (BSC 2004 [DIRS 171583], Table 2-1), the level of confidence 
(i.e., Level of Validation) required for the models developed in this report is Level III meaning 
the Level of Model Importance is high. A high level of confidence in the WPOB general and 
localized corrosion models will be obtained by building confidence in the methods used to 
develop the models and corroborating or validating the model output values and alternate 
conceptual models with those available in the peer reviewed scientific literature. 
7.1 CONFIDENCE BUILDING DURING MODEL DEVELOPMENT TO ESTABLISH 
SCIENTIFIC BASIS AND ACCURACY FOR INTENDED USE 
For Level III validation, the development of the model should be documented in accordance with 
the requirements of Section 5.3.2(b) of AP-SIII.10Q. The development of the general and 
localized corrosion models for the waste package outer barrier was conducted according to these 
criteria, as discussed below: 
1. Selection of input parameters and/or input data, and a discussion of how the selection 
process builds confidence in the model. [AP-SIII.10Q 5.3.2(b) (1) and AP-2.27Q 
Attachment 3 Level I (a)] 
The inputs to the general and localized corrosion models for the waste package outer 
barrier have all been obtained from controlled sources (Table 4-1, Section 4.1.1), 
including discussion about selection of input and design parameters. Model assumptions 
have been described in Section 5. Detailed discussion about model concepts can be 
found throughout Section 8 and particularly in Section 6.3. Thus, this requirement can be 
considered satisfied. 
2. Description of calibration activities, and/or initial boundary condition runs, and/or run 
convergences, simulation conditions set up to span the range of intended use and avoid 
inconsistent outputs, and a discussion of how the activity or activities build confidence in 
the model. Inclusion of a discussion of impacts of any non-convergence runs[(APSIII.
10Q 5.3.2(b)(2) and AP-2.27Q Attachment 3 Level I (e)]. 
Discussion of initial and boundary conditions are described in Sections 1.2, 6, and 8 
where the waste package degradation models and ranges of application are discussed. 
Sections 6.4.3 and 6.4.4 provide discussion of various model results (i.e., those of 
convergence runs). Discussion about nonconvergence runs is not applicable to this report 
because none were encountered. Thus, this requirement can also be considered satisfied. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-2 October 2004 
3. Discussion of the impacts of uncertainties to the model results including how the model 
results represent the range of possible outcomes consistent with important 
uncertainties.[(AP-SIII.10 Q 5.3.2(b)(3) and AP-2.27Q Attachment 3 Level 1 (d) and 
(f)]. 
Uncertainties associated with the waste package barriers capabilities are summarized in 
Sections 8.1, 8.2, and 8.3. More detailed discussions of the impact of uncertainties on the 
model results developed in this report are found in Sections 6.4.3, 6.4.4, and 6.4.5. 
Section 6.4.3 discusses the effects of data uncertainties on the general corrosion model 
developed in this report. Uncertainties in the data used for the general corrosion model 
analysis (5-year weight loss measurements and short-term polarization resistance 
measurements) were characterized and quantified, and propagated through the general 
corrosion model abstraction (Section 6.4.3). Section 6.4.4 discusses the effects of data 
uncertainties on the localized corrosion model developed in this report. Uncertainties in 
the data used for the localized corrosion model analysis (crevice repassivation potentials, 
and long-term steady-state corrosion potentials) were characterized and quantified, and 
propagated through the localized corrosion model abstraction (Section 6.4.4). A 
conservative bounding approach, based on the literature data for Alloy 22 in highly 
corrosive environments, was used to capture the uncertainty in the localized corrosion 
rate of Alloy 22 (Section 6.4.4). Section 6.4.5 discusses the effects of data uncertainties 
on the microbially influenced corrosion (MIC) model developed in this report. 
4. Formulation of defensible assumptions and simplifications. [AP-2.27Q Attachment 3 
Level I (b)]. 
Discussion of assumptions and simplifications are provided in Section 5 with appropriate 
technical bases for their use. 
5. Consistency with physical principles, such as conservation of mass, energy, and 
momentum. [AP-2.27Q Attachment 3 Level I (c)] 
Consistency with physical principles is demonstrated by the conceptual and mathematical 
formulation in Section 6.3 and 6.4, respectively. 
7.2 CONFIDENCE BUILDING AFTER MODEL DEVELOPMENT TO SUPPORT 
THE SCIENTIFIC BASIS OF THE MODEL 
Four validation activities were developed to ensure the required level of confidence in these 
models for their stated purposes has been achieved. Four validation activities are documented in 
the TWP for this activity (BSC 2004 [DIRS 171583], Table 2-1). The validation activities were 
developed to ensure the required level of confidence in these models has been achieved for their 
stated purposes are: 
Activity One: Show that the modeled propagation rates of general corrosion and localized 
corrosion of the waste package are reasonable and consistent with rates 
determined by alternative techniques or alternative models for the conditions 
expected in the repository. 
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Activity Two: Show that the modeled propagation rates of general corrosion and localized 
corrosion of the waste package reasonable and consistent with rates from 
literature data and natural or industrial analogues of relevant corrosion 
resistant alloys for the conditions expected in the repository. 
Activity Three: Show that the response of the correlations for Ecorr and Ecritical of the waste 
package are reasonable and consistent with literature data on relevant 
corrosion resistant alloys and available analogues for the conditions expected 
in the repository. 
Activity Four: Show that the response of the correlations for Ecorr and Ecritical of the waste 
package consistent with other alternative models for localized corrosion 
initiation for the conditions expected in the repository. 
The criterion for satisfying these validation activities is that the corroborating data must match 
qualitatively (BSC 2004 [DIRS 171583], Table 2-1). These validation activities are consistent 
with the model validation techniques given in AP-SIII.10Q, Models, Sections 5.3.2.c)2) 
and 5.3.2.c)3). A detailed description of the validation of the WPOB general and localized 
corrosion models in light of these validation activities follows. 
7.2.1 General Corrosion Model of the Waste Package Outer Barrier 
Validation of the general corrosion model of the WPOB requires meeting the salient parts of 
Activities One and Two. 
Activity One: Show that the modeled propagation rates of general corrosion and localized 
corrosion of the waste package are reasonable and consistent with rates 
determined by alternative techniques or alternative models for the conditions 
expected in the repository. 
Activity Two: Show that the modeled propagation rates of general corrosion and localized 
corrosion of the waste package reasonable and consistent with rates from 
literature data and/or natural analogues and/or industrial analogues of relevant 
corrosion resistant alloys for the conditions expected in the repository. 
As described in Section 6.4.3.4, the base-case general corrosion model for the WPOB is based on 
a temperature dependence of the corrosion process, represented by an activation energy using the 
natural logarithmic form of a modified Arrhenius relation. The model is expressed as follows: 
.. 
. 
.. 
. - + = 
15 . 333
1 1 ) ln( ) ( ln 1 T 
C R R o T (Eq. 7-1) 
RT is temperature-dependent general corrosion rate in nm/yr, T is temperature in Kelvin, and Ro 
and C1 are constants. The temperature dependence term (C1) was obtained from short-term 
polarization resistance data for Alloy 22 specimens tested for a range of sample configurations, 
metallurgical conditions, and exposure conditions. See Section 6.4.3.4 for details of the model 
derivation and parameter evaluation. A normally distributed temperature-dependence term with 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-4 October 2004 
a mean of 3,116.47 K and a standard deviation of 296.47 K was chosen. The activation energy 
was estimated to be 25.9  2.5 kJ/mol. The general corrosion rate distribution (Ro) derived from 
the weight-loss data of the 5-year crevice specimens was fit to a Weibull distribution 
(s = 8.88 nm/yr, b = 1.62, and l = 0 nm/yr). This distribution is considered to represent the 
distribution of long-term general corrosion rates of the WPOB at 60C. The median 
(50th percentile) rate of Ro is 7.08 nm/yr, and the 99.999th percentile rate is 40.1 nm/yr. 
The validation of the general corrosion model consists of two parts: evaluation of the activation 
energy value (or the temperature dependence term, C1) of the model and evaluation of the 
general corrosion rates predicted by the model. As discussed below, the evaluation was 
performed by comparing the aforementioned model properties with the literature data for 
corrosion-resistant alloys similar to Alloy 22 measured in repository relevant environmental 
conditions. 
Temperature dependence of the passive corrosion rate of Alloy 22 was also reported by other 
investigators. Based on the passive current densities of Alloy 22 measured in 5 M LiCl solutions 
with small amounts of ] [ 4
- SO and ] [ 3
- NO added (Scully et al. 2001 [DIRS 154513], Table 4, 
Section 1.4), an activation energy of 36 kJ/mol was estimated (BSC 2001 [DIRS 155950], 
Section 7.3.5.3). The same analysis also estimated an activation energy of 32 kJ/mol from the 
measured passive current densities of Alloy 22 polarized at 350 mV vs SSC in a solution of 1 M 
NaCl and 0.1 M H2SO4 (Lloyd et al. 2003 [DIRS 167921]). EPRI (2002 [DIRS 158069], 
Section 5.3.2) estimated an activation energy of 19 kJ/mol for Alloy C-4 from the corrosion rates 
from weight-loss measurements of the alloy measured over a period of 3 to 5 years at 
temperatures in the range of 90C to 200C in saturated Mg2+-dominated brines 
(Smailos et al. 1987 [DIRS 159774]). A recent study sponsored by the Project estimated 
activation energies of 26.8 kJ/mol and 24.9 kJ/mol for annealed Alloy 22 and welded Alloy 22 
samples, respectively. The activation energies were determined from corrosion rates based on 
the weight-loss measurements in BSW solutions at temperatures from 60C to 105C for 
eight weeks (Hua 2002 [DIRS 162256], p. 90, Table 8-2). 
An analysis of the effect of temperature on the passive corrosion of Alloy 22, conducted by 
researchers at the CNWRA, reported a mean apparent activation energy of 44.7 kJ/mol with a 
standard deviation of 5.5 kJ/mol, based on potentiostatic anodic current measurements of smooth 
cylindrical specimens polarized at 100 mVSCE in de-aerated 0.028 M NaCl solutions 
(Pensado et al. 2002 [DIRS 166944], Section 4.3). In the tests, the temperature was decreased 
from 95C to 80C to 60C to 40C to 25C at defined times over a total test duration of 
about 900 hours. The higher activation energy of the above study than that of the base-case 
general corrosion model in this report may have been caused by the combined effects of the 
exposure time and the order of the temperature changes (i.e., decrease from high temperature to 
low temperature). This test approach would yield higher passive corrosion rates at the higher 
temperatures and lower passive corrosion rates at lower temperatures, thus giving a higher 
activation energy than the approach used by Lloyd et al. (2003 [DIRS 167921]) in which the test 
temperature changed from low to high in the potentiostatic passive current measurements. 
Another factor to consider is that CNWRA researchers (Dunn and Brossia 2002 [DIRS 162213]) 
found a temperature dependence of the passive corrosion rate of Alloy 22 in low salinity 
solutions (0.028 M [Cl-]), but no temperature dependence at higher salinities (4.0 M [Cl-]), which 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-5 October 2004 
are more relevant to the repository. The temperature dependence resulting from studies at higher 
chloride concentrations (e.g., Scully et al. 2001 [DIRS 154513]; Lloyd et al. 2003 
[DIRS 167921]; EPRI 2002 [DIRS 158069]; Hua 2002 [DIRS 162256]) are more relevant. 
Considering these factors, the apparent activation energy value and its standard deviation 
reported by Pensado et al. (2002 [DIRS 166944], Section 4.3) is not considered relevant. 
In another study, CNWRA researchers reported a calculated activation energy of 46.3 kJ/mol for 
the temperature dependence of Alloy 22 general corrosion in 0.028 M NaCl over the temperature 
range between 25C and 95C (Dunn et al. 2004 [DIRS 171452]), and an activation energy of 
49.6 kJ/mol in a 35-percent MgCl2 solution for the temperature range between 40C and 120C. 
The activation energy obtained in the dilute chloride solution (0.028 M NaCl) is not considered 
relevant as discussed previously. The Alloy 22 corrosion rates in the 35-percent MgCl2 solution 
were more than an order of magnitude greater than those obtained in the 0.028 M NaCl solution 
indicating that the aggressive MgCl2 solution may have disrupted the stability of the passive film 
(Dunn et al. 2004 [DIRS 171452]) leading to active (rather than passive) corrosion. On this 
basis, the activation energy obtained in the 35-percent MgCl2 solution is not relevant to the 
passive corrosion conditions for which the general corrosion model was developed. 
As indicated by the literature data cited above, the temperature dependence of general corrosion 
of Alloy 22 and other similar corrosion-resistant Ni-Cr-Mo alloys is about the same as that used 
in the base-case general corrosion model in this report considering the differing conditions 
(especially solution chemistry and sample condition) employed in the tests. Also, as shown by 
the 5-year weight-loss data (Section 6.4.3.2, Appendices II and III) and the corrosion rates from 
the polarization resistance measurements (Section 6.4.3.4, Appendix IV), there is no significant 
dependence of the Alloy 22 general corrosion rate on metallurgical conditions and sample 
geometry. In addition, the activation energy of the Alloy 22 general corrosion rate obtained in 
this report is similar to the results of the other investigators cited above. It is noted that the 
activation energies of general corrosion rate of highly corrosion-resistant Ni-Cr-Mo alloys are 
similar regardless of the exposure time in the test environments. That is, the temperature 
dependence of the Alloy 22 general corrosion rate does not change significantly as the general 
corrosion rate decreases with the exposure time. 
Because of the extremely low corrosion rates of Alloy 22, there are little data for Alloy 22 in the 
scientific literature that could be used to evaluate the general corrosion model. However, similar 
passive corrosion behavior has also been observed for Ni-Cr-Mo corrosion-resistant alloys. For 
example, Alloy C (UNS N06455) is found to retain a very thin passive film, indicated by the 
mirror-like surface finish observed after 44 years of exposure at Kure Beach to a marine 
environment (i.e., salt air with alternate wetting and drying, as well as the presence of surface 
deposits) (Baker 1988 [DIRS 154510], p. 134 and Table 6). More recent examination of 
specimens from this alloy after more than 50 years of exposure indicates that the samples 
continue to maintain a mirror-like finish and passive film behavior (McCright 1998 
[DIRS 114637], Figure ES-1). Under these same conditions, the less corrosion-resistant 
Alloy 600 exhibited a corrosion rate of 8 nm/yr after 36 years of exposure. This long-term 
corrosion rate is consistent with the model prediction. 
The 50th, 95th and 99.99th (reasonable upper bound) percentile rates at 25C for the mean 
activation energy (25.91 kJ/mol) predicted by the general corrosion model are 2.4, 5.8, 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-6 October 2004 
and 11.7 nm/yr, respectively (Figure 6-26 25C model result CDF; 
DTN: MO0409MWDUGCMW.000). For the lower bound activation energy (18.53 kJ/mol) 
those rates predicted by the model are 3.2, 8.0, and 15.9 nm/yr respectively (Figure 6-28 25C 
model result CDF; DTN: MO0409MWDUGCMW.000). As discussed above, the general 
corrosion behavior of corrosion-resistant Ni-Cr-Mo alloys are similar. These long-term results 
corroborate the expected excellent long-term passive behavior of Alloy 22 under 
chloride-containing aqueous environments relevant to repository exposure conditions. 
The model validation for intermediate and elevated temperature conditions was performed by 
comparing the model results to the recently reported weight-loss measurements of MA and ASW 
Alloy 22 MCA specimens after exposure to the BSW solutions at temperatures from 60C to 
105C over a period of 8 weeks (Hua et al. 2002 [DIRS 160670]). From the 8-week weight-loss 
measurements, an average general corrosion rate of 75 nm/yr at 60C and 300 nm/yr at 105C 
were reported for the Alloy 22 MCA specimens. The model calculated 50th, 95th and 99.99th 
(reasonable upper bound) percentile rates at 60C for the mean activation energy (25.91 kJ/mol) 
are 7.1, 17.5, and 35.0 nm/yr respectively. For the 105C condition, the model calculated 50th, 
95th, and 99.99th percentile rates are 21.6, 53.2, and 106 nm/yr respectively for the mean 
activation energy (25.91 kJ/mol), and 29.6, 73.1, and 146 nm/yr respectively for the upper bound 
activation energy (33.29 kJ/mol). Although the upper bound rates of the model are consistent 
with the data, it appears the model predicted general corrosion rates are generally lower than 
the 8-week exposure data. However, considering the shorter-term nature of the data (compared 
to the 5-year data used in the model), the model results are in a good agreement with the data 
obtained in this repository relevant exposure environment. 
The model predictions for high temperature chloride-containing brines are also consistent with 
general corrosion rate data for surface-welded Alloy C-4 samples tested at 150C in NaCl-rich 
brines (Smailos 1993 [DIRS 168164], Table IV). The samples corroded uniformly under the test 
conditions. As discussed above, the general corrosion behavior of corrosion-resistant Ni-Cr-Mo 
alloys are similar. A mean general corrosion rate of 70 nm/yr and 60 nm/yr was reported for 
12-month and 18-month test periods, respectively. The reported general corrosion rates are the 
average values of five samples. For the same NaCl-rich brines containing 6  10-4 M Na2S, the 
reported mean general corrosion rates of the surface-welded alloy were 510 nm/yr and 120 nm/yr 
for 12-month and 18-month test periods, respectively. 
The model calculated 50th, 95th and 99.99th percentile rates at 150C for the mean activation 
energy (25.91 kJ/mol) are 52, 128, and 256 nm/yr, respectively (Figure 6-26 150C model result 
CDF; DTN: MO0409MWDUGCMW.000). For the upper bound activation energy 
(33.29 kJ/mol), the model calculated 50th, 95th and 99.99th percentile rates at 150C 
are 91, 225, and 451 nm/yr, respectively (Figure 6-27 150C model result CDF; 
DTN: MO0409MWDUGCMW.000). The 150C model results for the lower-bound activation 
energy (18.53 kJ/mol) are 29, 73, and 145 nm/yr, respectively (Figure 6-28 150C model result 
CDF; DTN: MO0409MWDUGCMW.000). As demonstrated above, the predicted general 
corrosion rates for high-temperature chloride-containing brines are consistent with literature data 
for Alloy C-4 whose general corrosion behavior is expected to be similar to Alloy 22 for the 
conditions expected in the repository. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-7 October 2004 
The general corrosion rate is temperature dependent, and for a given temperature, it is assumed 
constant (i.e., time independent) (Assumption 5.2). Therefore, for a given temperature, the depth 
of penetration or thinning of the WPOB by general corrosion is equal to the general corrosion 
rate at that temperature, multiplied by the time duration that the waste package surface is at that 
temperature. However, general corrosion rates of metals and alloys tend to decrease with time. 
The dependence of the general corrosion rate of Alloy 22 on the exposure time is shown in 
Figure 7-1 for the mean general corrosion rates of Alloy 22 at 90C, measured with different test 
techniques (potentiostatic polarization, polarization resistance, and weight-loss measurements) 
for exposure times up to 5 years. Given the differences between the techniques used to 
determine corrosion rates presented in the figure, some variation about the central trend line is to 
be expected. A trend-line was drawn for better visualization of the data trend. The data shown 
in the figure are summarized in Table 7-1. 
The exposure time ranges from one day to 5-plus years exposure at the LTCTF. Each data point 
for the 6-month, 1-year, and 2-year weight-loss measurements in the figure is the mean of at 
least 144 samples (CRWMS M&O 2000 [DIRS 153802], p. 3-39). The 5-year general corrosion 
rate is the mean of the weight-loss measurements of 59 crevice samples from the LTCTF (Table 
6-6 and Section 6.4.3.4). The mean general corrosion rate of the crevice samples after 5-year 
exposure at the LTCTF was 0.0072 m/yr, and the standard deviation was 0.005 m/yr. It is 
noted that the corrosion rates measured by short-term electrochemical techniques provide 
corroboration of the rates from weight-loss method. The trend of decreasing general corrosion 
rate with time is consistent with the expected corrosion behavior of passive alloys such as 
Alloy 22 under repository-type aqueous conditions. The current conservative approach for the 
constant (time-independent) general corrosion rate at a given temperature in the waste package 
degradation analysis provides an additional confidence for the general corrosion model. 
A comparison of the rates obtained from the temperature-dependent general corrosion model 
with the rates from alternative techniques from the scientific literature shows that Activities One 
and Two have been met. In addition, the conservative approach used in calculating the 
penetration depth by general corrosion over time would provide an additional confidence to the 
model and the modeling approach. 
Table 7-1. Summary of Mean General Corrosion Rates of Alloy 22 at 90C Versus Exposure Time 
Exposure Time 
(years) (days) 
Mean Rate 
(m/yr) Sources 
0.0027 1 0.460 Lian et al. 2002 [DIRS 164856], Table 3, potentiostatic polarization technique 
at 100 mV versus SSC applied potential in SAW, 90C, N2 purge. 
0.0027 1 1.250 Lian et al. 2002 [DIRS 164856], Table 3, potentiostatic polarization technique 
at 100 mV versus SSC applied potential in SCW, 90C, N2 purge. 
0.019 7 0.100 Evans and Rebak 2002 [DIRS 164857], Figure 2, polarization resistance 
technique, after 1 week in open-circuit potential in SAW, 90C, air purge. 
0.154 56 0.182 Hua 2002 [DIRS 162256], p. 97, calculated from regression fit for 56-day 
weight loss in BSW, CR (MPY) = 31.3*exp(-25300/RT). 
0.50 183 0.050 CRWMS M&O 2000 [DIRS 153802] (p. 3-39), LTCTF weight-loss data 
1.00 365 0.030 CRWMS M&O 2000 [DIRS 153802] (p. 3-39), LTCTF weight-loss data 
2.30 840 0.010 CRWMS M&O 2000 [DIRS 153802] (p. 3-39), LTCTF weight-loss data 
5.06 1,846 0.007 Section 6.4.3.3, Table 6-6 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-8 October 2004 
Source: Table 7-1. 
Figure 7-1. Decrease of the Mean General Corrosion Rate of Alloy 22 with Time 
7.2.2 Corrosion Potential Model of the Waste Package Outer Barrier 
Validation of the corrosion potential model of the WPOB requires meeting the salient portion of 
Activity Three. 
Activity Three: Show that the response of the correlations for Ecorr and Ecritical of the waste 
package are reasonable and consistent with literature data on relevant 
corrosion resistant alloys and available analogues for the conditions expected 
in the repository. 
The long-term corrosion potential model developed to analyze the localized corrosion behavior 
of the WPOB under the conditions expected in the repository is expressed as follows: 
. .. 
. 
. .. 
. 
+ + + + = 
] [ 
] [ 
log ] [ 3 
4 3 2 1 0 Cl 
NO c Cl c pH c T c c Ecorr (Eq. 7-2) 
where corr E is the long-term corrosion potential in mV versus SSC, T is the temperature (C), 
] [Cl is the chloride ion concentration in moles per kg water, ] [ 3 NO is the nitrate ion 
concentration in moles per kg water, and c0, c1, c2, c3, and c4 are coefficients of the model 
parameters. The model parameters were evaluated by fitting the model to the long-term 
corrosion potential data. The estimated regression coefficients and their uncertainty ( 1 standard 
deviation) are: = 0 c 558.283  36.156, = 1 c 0.677  0.413, = 2 c -65.338  2.456, = 3 c -7.616  
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-9 October 2004 
1.581, and = 4 c 37.077  2.443. This model is to estimate the long-term steady-state opencircuit 
corrosion potential of Alloy 22 for a range of exposure conditions related to the 
repository. The model is not intended to predict short-term corrosion potential because the 
corrosion potential of Alloy 22 evolves with time under the conditions relevant to the repository. 
Few data exist for the steady-state corrosion potential of Alloy 22 for conditions related to the 
repository that can be used to evaluate the corrosion potential model. A study sponsored by the 
U.S. Department of Energy Nuclear Energy Research Initiative published measurements of the 
open-circuit corrosion potential of Alloy 22 under air-saturated conditions in a saturated NaCl 
solution (pH = 3) at 80C for a period of 200 days (Jayaweera et al. 2003 [DIRS 162225], 
pp. 9-18 to 9-22, Figure 9.13). The chloride ion concentration of the solution was 
about 6.2 molal. The measured corrosion potential at the end of the testing (200 days) ranges 
from about 160 to 250 mV versus standard hydrogen electrode. For these exposure conditions, 
the mean value of the corrosion potential from the long-term corrosion potential model 
is 229 mV SSC, and 2 standard deviation values are 250 and 207 mV SSC, respectively. 
At 25C (77F), the Ag/AgCl scale with the reference electrode in saturated KCl solution is more 
noble than the standard hydrogen electrode scale by 199 mV (Sawyer and Roberts 1974 
[DIRS 162259], pp. 39 to 45, Table 2-4). Therefore, the model-predicted corrosion potentials in 
the standard hydrogen electrode scale are 428 mV (mean), 449 mV (plus 2 standard deviations), 
and 406 mV (minus 2 standard deviations). Although the lower-bound of the model-predicted 
corrosion potential (406 mV versus standard hydrogen electrode) is higher than 
Jayaweera et al.s (2003 [DIRS 162225], pp. 9 to 18) results (160 to 250 mV versus standard 
hydrogen electrode) by about 150 mV, the model prediction is considered a reasonably good 
match considering that the investigators indicated that the corrosion potential had likely not 
reached steady state. In addition, overestimates of the corrosion potential by the model are 
conservative because, for a given condition, the overestimates could result in localized corrosion 
initiation under conditions in which it would not be observed. 
Dunn et al. (2003 [DIRS 166948], Figures 4-17 and 4-18) reported the corrosion potential data of 
Alloy 22 in air-saturated 0.028 M NaCl solutions as a function of immersion time for 
approximately 60 days. These data were also used to validate the corrosion potential model. 
The corrosion potentials appeared to stabilize after 60 days of testing, but there were significant 
spreads of data for the near-neutral and alkaline conditions. Comparing to the longer-term 
corrosion potential data of Alloy 22 samples tested in air-saturated and more concentrated NaCl 
solutions (Jayaweera et al. 2003 [DIRS 162225], pp. 9-18 to 9-22, Figure 9.13), it is likely that 
the corrosion potentials may have not yet reached the steady state after 60 days of testing. The 
corrosion potential data after 60 days of testing, read from the figures, are summarized in the first 
four rows of Table 7-2, along with the environmental condition inputs to the model calculations 
and model predicted corrosion potentials. Because the model predicted corrosion potential is in 
the SSC scale, the reported corrosion potential data in the SCE scale were converted to the SSC 
scale by adding 42 mV. The fifth row in Table 7-2 contains one corrosion potential observation 
measured from an Alloy 22 crevice corrosion test specimen exposed to an air-saturated 4 M Clsolution 
(Dunn et al. 2003 [DIRS 164138], pp. 2 and 5). The specimen was periodically 
removed and examined for signs of localized corrosion (Dunn et al. 2003 [DIRS 164138], p. 5). 
During over 750 days of testing, no localized corrosion was observed (Dunn et al. 2003 
[DIRS 164138], p. 5). Over the last 200 days of testing the corrosion potential reached a 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-10 October 2004 
maximum value near -100 mVSCE. As summarized in Table 7-2, the model predictions are 
consistent with the cited literature data. 
Table 7-2. Summary of Model Validation Analysis for the Corrosion Potential Model 
Ecorr Model c) 
Test Condition, and Data 
Source a) 
Measured 
Ecorr 
(mVSCE) 
Measured Ecorr 
(mVSSC) b) 
Environmental Condition 
Inputs to Model 
Calculation Mean 
(mVSSC) 
2 s.d. (mVSSC) 
Alloy 22 thermally 
oxidized; air-saturated 
0.028 M NaCl, 0.16 mM 
NO3
-, 95C, pH 10.6 to 
11.7 (Dunn et al. 2003 
[DIRS 166948], Figure 
4-17) 
-300 to 
-100 -258 to -58 
Alloy 22 polished; airsaturated 
0.028 M 
NaCl, 0.16 mM NO3
-, 
95C, pH 10.6 to 11.7 
(Dunn et al. 2003 [DIRS 
166948], Figure 4-17) 
-200 to 0 -158 to 42 
0.028 m [Cl], 0.00016 m 
[NO3], 95C, pH 11.2 
(mid-point) 
-143 
-175 (-2 s.d.) 
-112 (+2 s.d.) 
Alloy 22 thermally 
oxidized; air-saturated 
0.028 M NaCl, 0.16 mM 
NO3
-, 95C, pH 8.2 to 
9.3 (Dunn et al. 2003 
[DIRS 166948], Figure 
4-18) 
-120 to 
70 -78 to 112 
0.028 m [Cl], 0.00016 m 
[NO3], 95C, pH 8.8 
(mid-point) 
-6 
-30 (-2 s.d.) 
18 (+2 s.d.) 
Alloy 22 thermally 
oxidized; air-saturated 
0.028 M NaCl, 0.16 mM 
NO3
-, 95C, pH 2.7 to 
2.8 (Dunn et al. 2003 
[DIRS 166948], Figure 
4-18) 
250 to 
270 292 to 312 
0.028 m [Cl], 0.00016 m 
[NO3], 95C, pH 2.75 
(mid-point) 
389 
365 (-2 s.d.) 
413 (+2 s.d.) 
Alloy 22 crevice 
specimen, air saturated 
4 M Cl-, 0.16 mM NO3
-, 
95C (Dunn et al. [DIRS 
164138], p. 2 and 5) 
-100 -58 4.51 m [Cl] d), 0.00016 
m [NO3], 95C, pH 6.3 d) 41 
25 (-2 s.d.) 
57 (+2 s.d.) 
NOTES: a) Some Alloy 22 samples were thermally oxidized at 200C for 30 days. 
b) At 25C the saturated calomel reference electrode (SCE) is 42 mV more noble than the silver-silver 
chloride reference electrode (SSC). The SCE scale potentials were converted to the SSC scale 
potentials by adding 42 mV. 
c) The values in these columns are obtained by substituting the environmental condition inputs into the 
equation used to determine the corrosion potential (Ecorr(T,pH,Cl,NO3,z) in Appendix IX on p. IX-14). z = 
0 gives the mean, z = 2 gives the 2 s.d. values. 
d) pH of 6.3 and Cl- molality from Cell 18 in Appendix V (4 M NaCl solution). 
A comparison of the long-term corrosion potential obtained from the long-term corrosion 
potential model with the long-term corrosion potential data of Alloy 22 measured independently 
has shown that the salient portion of Activity Three relating to the long-term corrosion potential 
model has been met. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-11 October 2004 
7.2.3 Critical Potential Model of the Waste Package Outer Barrier 
Validation of the critical potential model of the WPOB requires meeting the salient portion of 
Activity Three. 
Activity Three: Show that the response of the correlations for Ecorr and Ecritical of the waste 
package are reasonable and consistent with literature data on relevant 
corrosion resistant alloys and available analogues for the conditions expected 
in the repository. 
Ecritical can be defined as a threshold potential above which the current density or corrosion rate 
of Alloy 22 increases significantly and irreversibly above the general corrosion rate of the 
passive metal. As a conservative measure, the base-case localized corrosion model uses the 
crevice repassivation potential (Ercrev) as the critical potential for the localized corrosion 
initiation analysis. The crevice repassivation potential (Ercrev) is expressed as follows. 
- . + = 3 NO 
rcrev 
o
rcrev rcrev E E E (Eq. 7-3) 
where o
rcrev E is the crevice repassivation potential in the absence of inhibitive nitrate ions, and 
- . 3 NO 
rcrev E is the crevice repassivation potential change resulting from the inhibiting effect of nitrate 
ion in solution. The crevice repassivation potential of Alloy 22 in the absence of inhibitive 
nitrate ion is expressed as follows. 
]) log([ ]) log([ 4 3 2 1 Cl T a Cl a pH a T a a E o 
o
rcrev  + + + + = (Eq. 7-4) 
where ao, a1, a2, a3, and a4 are constants, T is the temperature (C), and ] [Cl is the chloride ion 
concentration in moles per kg water. The value of the coefficients and their uncertainty 
(1 standard deviation) of the model parameters from the least square fitting were determined to 
be: = 0 a 214.089  46.880, = 1 a -3.696  0.476, = 2 a 25.284  5.641, = 3 a -252.181  53.912, 
and = 4 a 1.414  0.547. 
The effect of nitrate ion on the crevice repassivation potential is represented by the following 
functional form: 
] [ 
] [ 
] [ 3 
2 3 1 
3 
Cl 
NO b NO b b E o 
NO 
rcrev + + = . - (Eq. 7-5) 
where ] [Cl is the chloride ion concentration in moles per kg water, ] [ 3 NO is the nitrate ion 
concentration in moles per kg water, and bo, b1, and b2 are constant. The parameter coefficients 
and their uncertainty (1 standard deviation) resulting from the fitting procedure were 
determined to be: = o b 22.589  24.113, = 1 b 33.748  5.180, and = 2 b 749.745  95.491. 
There are limited data in the scientific literature for the crevice repassivation potential of 
Alloy 22 for the conditions relevant to the repository. Even for those literature data that may be 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-12 October 2004 
applicable, it is difficult to use those data to evaluate the critical potential model because they 
were obtained using different criteria and/or measurement approaches (Section 6.4.4.1). 
There are three crevice repassivation potential data points for Alloy 22 previously reported by 
the investigators at the CNWRA for the NRC (Dunn et al. 1999 [DIRS 154481], Figures 3-6 
and 3-9). These data were not included in Effect of Environment on the Corrosion of Waste 
Package and Drip Shield Materials (Brossia et al. 2001 [DIRS 159836]) and not included in the 
crevice repassivation model development. These data are summarized in Table 7-3. The crevice 
repassivation potentials were read from the figures referenced. As shown in the table, the model 
predicted crevice repassivation potentials of Alloy 22 agree with the measured data 
within 100 mV. This represents an acceptable level of agreement between the model and the 
measured data particularly in light of the subjective nature of the selection of critical potentials 
from CPP curves and the dynamic nature of the measurement technique (Section 6.4.4.1). Also, 
according to the localized corrosion initiation model developed in this report, localized corrosion 
would initiate under these essentially pure chloride exposure conditions (e.g., Figure 6-61 for 
95C, 10 m chloride, and 0.01 m nitrate). 
A comparison of the crevice repassivation potential obtained from the long-term corrosion 
potential model with the crevice repassivation potential data of Alloy 22 measured independently 
has shown that the salient portion of Activity Three relating to the crevice repassivation model 
has been met. 
Table 7-3. Summary of Model Validation Analysis for Crevice Repassivation Potential Model 
Ercrev Model b) Exposure 
Environment and 
Data Source 
Measured 
Ercrev 
(mVSCE) 
Measured 
Ercrev 
(mVSSC) a) 
Environmental Condition 
Inputs to Model Calculation Mean (mVSSC) 2 s.d. (mVSSC) 
0.5 M NaCl, 10 ppm 
NO3, pH 8, 175C 
(Dunn et al. 1999 
[DIRS 154481], 
Figure 3-9) 
-275 -233 0.51 m [Cl], 0.00016 m 
[NO3], pH 8, 175C -229 
-143 (+2 s.d.) 
-315 (-2 s.d.) 
9 M LiCl, 10 ppm 
NO3, pH 5.6, 95C 
(Dunn et al. 1999 
[DIRS 154481], 
Figure 3-7) 
-230 -188 
11 m [Cl] (estimated) c), 
0.00016 m [NO3], pH 5.6, 
95C 
-118 
-100 (+2 s.d.) 
-136 (-2 s.d.) 
11 M LiCl, 10 ppm 
NO3, pH 5.6, 95C 
(Dunn et al. 1999 
[DIRS 154481], 
Figure 3-7) 
-260 -218 
13 m [Cl] (estimated) c), 
0.00016 m [NO3], pH 5.6, 
95C 
-127 
-108 (+2 s.d.) 
-146 (-2 s.d.) 
NOTES: a At 25C the saturated calomel reference electrode (SCE) is 42 mV more noble than the silver-silver 
chloride reference electrode (SSC). The SCE scale potentials were converted to the SSC scale 
potentials by adding 42 mV. 
b The values in these columns are obtained by substituting the environmental condition inputs into the 
equation used to determine the critical potential (Ecrit(T,pH,Cl,NO3,z) in Appendix IX on p. IX-14). z = 0 
gives the mean, z = 2 gives the 2 s.d. values. 
c The values of chloride ion molality are estimated. Given that these values are not direct input to this 
report, estimation of the chloride ion molality is acceptable for this usage. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-13 October 2004 
7.2.4 Localized Corrosion Initiation Model of the Waste Package Outer Barrier 
The discussion in this section considers the correlations for Ercrev and Ecorr (or more accurately 
their difference, .E = Ercrev  Ecorr) and compares the predicted results with experimental 
data/observations and the alternative conceptual model discussed in Section 6.4.4.8.1. These 
discussions relate to Activities Three and Four. 
Activity Three: Show that the response of the correlations for Ecorr and Ecritical of the waste 
package are reasonable and consistent with literature data on relevant 
corrosion resistant alloys and available analogues for the conditions expected 
in the repository. 
Activity Four: Show that the response of the correlations for Ecorr and Ecritical of the waste 
package consistent with other alternative models for localized corrosion 
initiation for the conditions expected in the repository. 
Additional model validation was performed by comparing the model predictions for localized 
corrosion susceptibility with relevant observations. As discussed in Section 6.4.3 for the WPOB 
general corrosion model analysis, Alloy 22 crevice samples were tested for over 5 years in three 
different solutions (SDW, SCW, and SAW) in the long-term corrosion testing facility (LTCTF). 
None of the crevice samples has suffered localized corrosion attack after being tested for over 5 
years. Also Dunn et al. (2003 [DIRS 164138], pp. 2 and 5) exposed an Alloy 22 crevice 
corrosion test specimen to an air saturated 4 M Cl- solution for over 750 days. The specimen was 
periodically removed and examined for signs of localized corrosion (Dunn et al. 2003 
[DIRS 164138], p. 5). During over 750 days of testing, no localized corrosion was observed 
(Dunn et al. 2003 [DIRS 164138], p. 5). These observations are used for model validation of the 
localized corrosion initiation model (i.e., crevice repassivation potential model in conjunction 
with the corrosion potential model). 
The analysis results are summarized in Table 7-4. As indicated by the results in the table, the 
model predicts no localized corrosion occurrence for the exposure conditions of the 5-year 
LTCTF crevice samples. The model predicts that localized corrosion will occur in the air 
saturated 4 M Cl- solution. These results show that the crevice corrosion initiation model (crevice 
repassivation potential model, in conjunction with the corrosion potential model) adequately 
predicts the crevice corrosion susceptibility of Alloy 22 and is conservative in some cases. 
Table 7-4. Comparison of Model Prediction for Localized Corrosion Susceptibility with Experimental 
Observations of Alloy 22 Crevice Samples Tested for Over 5 Years in LTCTF 
Long-Term Immersion Test Results Model Results 
Exposure 
Environment 
Crevice 
Corrosion 
Observation 
pH a 
[Cl] 
(moles/kg 
water) a 
[NO3] 
(moles/kg 
water) a 
Mean Ecorr 
(mV vs. 
SSC) b 
Mean Ercrev 
(mV vs. 
SSC) b 
Mean .E 
(Ercrev  Ecorr) 
(mV vs. SSC) 
SDW, 90C No 8.5 0.00325 0.000313 45 407 362 
SCW, 90C No 10.91 0.214 0.114 -106 642 748 
SAW, 90C No 3.83 0.838 0.426 351 400 49 
Alloy 22 crevice 
specimen, air No 6.3 4.51 0.00016 41 -55 -96 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-14 October 2004 
Long-Term Immersion Test Results Model Results 
Exposure 
Environment 
Crevice 
Corrosion 
Observation 
pH a 
[Cl] 
(moles/kg 
water) a 
[NO3] 
(moles/kg 
water) a 
Mean Ecorr 
(mV vs. 
SSC) b 
Mean Ercrev 
(mV vs. 
SSC) b 
Mean .E 
(Ercrev  Ecorr) 
(mV vs. SSC) 
saturated 4 M 
Cl-, 0.16 mM 
NO3
-, 95C 
(Dunn et al. 
[DIRS 164138], 
pp. 2 and 5) 
NOTES: SDW = simulated dilute water, SCW = simulated concentrated water, SAW = simulated acidified water. 
aThe pH values and molal concentrations are from the values in Appendix V for aged SDW (Cell 6), SCW 
(Cell 3), SAW (Cell 10), and 4 M NaCl (Cell 18) solutions. For the very dilute 0.16 mM NO3
- concentration, the 
molar value is used. 
bEcorr was calculated using Equation 7-2, and Ercrev using Equation 7-3. 
Smailos (1993 [DIRS 168164]) tested Alloy C-4 (a nickel-based alloy similar to Alloy 22 
(ASTM B 575-94 [DIRS 100497])) in two aggressive MgCl2-based brines and one NaCl-based 
brine at 150C for up to 18 months. The compositions of these brines are listed in Table 7-5. It 
was found that localized corrosion (pitting) was observed in Brines 1 and 2 (MgCl2-based), but 
not in Brine 3 (NaCl-based). 
Table 7-5. Compositions and pH Values of Salt Brines Used in Smailos 1993 [DIRS 168164] 
Weight Percent 
Brine NaCl KCl MgCl2 MgSO4 CaCl2 CaSO4 K2SO4 H2O pH 
(at 25C) 
1 1.4 4.7 26.8 1.4 0 0 0 65.7 4.6 
2 0.31 0.11 33.03 0 2.25 0.005 0 64.3 4.1 
3 25.9 0 0 0.16 0 0.21 0.23 73.5 6.5 
Source: Smailos 1993 [DIRS 168164], Table II. 
The model predicts localized corrosion will occur for all three brines (the nitrate-to-chloride ion 
ratio is less than 0.50 and the exposure temperature is between 120C and 160C 
(Section 6.4.4.6.7)). This result may be conservative for Brine 3 (NaCl-based); however, 
localized corrosion may have initiated in Brine 1 if the test duration had exceeded 18 months. 
Section 6.4.4.8.1 documents that temperature can be used as an alternative parameter to 
determine susceptibility to localized corrosion. Values of critical pitting temperature and critical 
crevice corrosion temperature have been measured for Alloy 22, in relatively pure concentrated 
chloride solutions (i.e., high salinity, [Cl-] = 24,300 g/g, and a high [Cl-] to [SO4
2-] ratio) 
(Haynes International 1997 [DIRS 100897], p. 9; McGuire et al. 1998 [DIRS 152193], 
Section 5.1.2). Under these highly corrosive conditions, the critical crevice corrosion 
temperature for Alloy 22 was measured to be 102C. The use of a critical temperature-based 
model is not advisable in TSPA-LA because it does not account for the effects of 
electrochemical characteristics of the solution contacting the metal, particularly those of 
important corrosion inhibiting anions such as nitrate ions present in the groundwater at the 
repository. Also, the localized corrosion initiation model developed in this report utilizes 
long-term corrosion potential data while the critical crevice corrosion temperature testing used a 
100-hour exposure period. Furthermore, several of the graphs in Section 6.4.4.6 (e.g., Figure 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-15 October 2004 
6-53, Figure 6-54, Figure 6-57, and Figure 6-58) indicate that the localized corrosion initiation 
model predicts the possibility for localized corrosion initiation at temperatures below 102C. 
This observation gives further confidence in the localized corrosion initiation model. 
The model validation documented in this section has shown that Activity Four has been met and 
provides additional confidence that Activity Three has been met. 
7.2.5 Localized Corrosion Penetration Model of the Waste Package Outer Barrier 
Validation of the localized corrosion penetration rate model of the WPOB requires meeting the 
salient parts of Activities One and Two. 
Activity One: Show that the modeled propagation rates of general corrosion and localized 
corrosion of the waste package are reasonable and consistent with rates 
determined by alternative techniques or alternative models for the conditions 
expected in the repository. 
Activity Two: Show that the modeled propagation rates of general corrosion and localized 
corrosion of the waste package reasonable and consistent with rates from 
literature data and/or natural analogues and/or industrial analogues of relevant 
corrosion resistant alloys for the conditions expected in the repository. 
Due to the outstanding corrosion resistance of Alloy 22, very little data exist for such localized 
corrosion under the conditions expected in the repository. The literature data for localized 
corrosion of relevant alloys that were considered for the current localized penetration rate model 
(Section 6.4.4.7) are for extremely corrosive conditions not expected in the repository. Those 
extreme penetration rates found in the literature were used to bound localized corrosion rates of 
Alloy 22 under repository conditions. 
In the development of the localized corrosion penetration model, it was noted that the Alloy 22 
average corrosion rate in a highly aggressive 10 percent ferric chloride crevice corrosion test 
solution was about 12.7 m/yr. The average corrosion rate of Alloy C-276 and Alloy C-4 
(Ni-Cr-Mo alloys similar to Alloy 22) in the same test solution were 1.4 mils/yr (35.6 m/yr) 
and 20 mils/yr (508 m/yr), respectively (Haynes International 1997 [DIRS 100897], p. 8). 
These values fall within the range of rates used for the Alloy 22 localized corrosion penetration 
model as well as illustrating that Alloy 22 is more corrosion resistant than these alloys. In a 
solution composed of 7 volume percent H2SO4, 3 volume percent HCl, 1 weight percent FeCl3, 
and 1 weight percent CuCl2, a penetration rate of 610 m/yr measured by weight loss was 
observed for Alloy C-276 at 102C (Gdowski 1991 [DIRS 100859], Table 23). This value also 
falls within the range of rates used for the Alloy 22 localized corrosion penetration model. 
Smailos (1993 [DIRS 168164]) tested Alloy C-4 in two aggressive MgCl2-based brines and one 
NaCl-based brine at 150C for up to 18 months. The compositions of these brines are listed in 
Table 7-5. It was found that localized corrosion (pitting) was observed in Brines 1 and 2 (the 
MgCl2-based brines) but not in Brine 3 (the NaCl-based brine). Maximum pit depths 
between 300 and 900 m were observed after 18 months of testing (Smailos 1993 
[DIRS 168164], Table III). These values correspond to pit penetration rates of between 200 and 
600 m/yr. These values fall within the range of rates used for the Alloy 22 localized corrosion 
penetration model. Pitting was not observed in Brine 1 at 12 months and the maximum pit depth 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 7-16 October 2004 
reported at 18 months was 300 m, which, assuming all pit growth occurred in 6 months, 
corresponds to a pit growth rate of 600 m/yr. Also, pitting was not observed in Brine 3 (the 
NaCl-based brine), which is likely to be more representative of repository conditions than 
MgCl2-based brines, after 18 months of testing although pitting may have initiated if the testing 
period were longer. 
In addition, the localized corrosion penetration model assumes that, when it occurs, localized 
corrosion of the WPOB propagates at a (time-independent) constant rate (Assumption 5.4). This 
assumption is highly conservative because it is known that the localized corrosion rate decreases 
with time, and this is particularly more likely under discontinuous and tortuous thin water film 
conditions expected on the waste package surface in the postclosure repository. Section 6.4.4.8.2 
provides further discussion on the above issues 
Based on the above discussion, the range of propagation rates used in the localized corrosion 
model of WPOB is reasonable and consistent with the literature data on relevant corrosionresistant 
alloys for the conditions expected in the repository. Therefore, Activities One and Two 
have been met. 
7.3 SUMMARY OF MODEL VALIDATION 
In light of the above discussion, it is concluded that the general and localized corrosion models 
for the WPOB and their output corroborate well with those reported in the scientific literature. It 
is also clear from the above discussion that the validation activities performed for building 
confidence in the model have sufficiently strong scientific bases, and that all of the validation 
activities used to determine that the required level of confidence in the model have been 
achieved have been met. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-1 October 2004 
8. CONCLUSIONS 
8.1 BASE-CASE MODEL SUMMARY 
This report documents the analyses and models for general and localized corrosion of the waste 
package outer barrier (WPOB). The purpose of the general and localized corrosion models are to 
analyze degradation of the Alloy 22 waste package outer barrier by general and localized 
corrosion processes under the expected repository environmental conditions over the repository 
performance period. The general and localized corrosion models include several submodels, 
which account for dry oxidation, aqueous general corrosion, microbially influenced corrosion 
(MIC), crevice corrosion initiation, and crevice corrosion growth. A model overview is 
graphically presented in Figure 8-1. 
Corrosion performance of the WPOB depends on the integrity of the thin adherent passive film 
formed on the alloy surface in contact with the exposure environments in the repository. The 
extremely low general corrosion rates and excellent resistance to localized corrosion of the 
WPOB in the repository intimately depend on the long-term stability of the passive film on the 
surface of the barrier. The passivity of Alloy 22 was evaluated by examining the oxide layers 
formed in a mixed-salt environment at 95C (Section 6.4.1.2). The surface analysis data 
indicated that the oxide layers responsible for passivity of Alloy 22 consist of chromium oxide 
(Cr2O3) containing nickel. The collected data indicated that (1) the passive films are very 
protective and stable, (2) contributions from metal corrosion become extremely small, and 
(3) redox reactions from the species in solution are stable. 
Dry oxidation is not a performance limiting process of the WPOB under the exposure conditions 
expected in the repository and is not considered for the waste package performance analysis 
(Section 6.4.2). Aging and phase instability of Alloy 22 is not expected to significantly impact 
the WPOB corrosion performance under the thermal conditions expected in the repository; 
therefore, this process is not considered in the waste package performance analysis 
(Section 6.4.6). 
General corrosion of the WPOB occurs when the RH at the waste package surface is equal to or 
greater than the RH threshold (RHthreshold) for corrosion initiation (Assumption 5.1). The general 
corrosion rate of the WPOB is a function of temperature, expressed with an activation energy 
using a modified Arrhenius relation (Section 6.4.3.4). Because of very low general corrosion 
rates of the WPOB for the conditions expected in the repository, waste package performance is 
not limited by general corrosion during the regulatory time period. As a bounding and 
conservative analysis, for a constant waste package surface temperature of 150C, the median 
penetration depth by general corrosion over 10,000 years, using the median general corrosion 
rate of 51.8 nm/yr, is about 518 m, which is less than 3 percent of the total thickness of the 
WPOB (20 mm). An even more conservative approach is to use the general corrosion rate of 
256 nm/yr (99.99th percentile rate at 150C), for which the total penetration depth by general 
corrosion is about 2,560 m after 10,000 years, which is less than 13 percent of the total 
thickness of the WPOB. This bounding analysis demonstrates that the waste package 
performance in the repository is not limited by general corrosion. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-2 October 2004 
The WPOB is subject to MIC when the relative humidity at the waste package surface is equal to 
or greater than 90 percent (Section 6.4.5). The MIC effect is represented by an enhancement to 
the abiotic general corrosion rate of the WPOB. 
Localized corrosion of the WPOB is modeled with a crevice corrosion initiation model and a 
propagation model (Section 6.4.4). The initiation model considers that crevice corrosion of the 
WPOB occurs when the steady-state corrosion potential (Ecorr) is equal to or greater than the 
crevice repassivation potential (Ercrev), that is, .E (= Ercrev - Ecorr) = 0. The WPOB is not subject 
to crevice corrosion if the solution contacting the waste package has a neutral to alkaline pH and 
contains significant concentrations of inhibitive ions such as nitrate. The WPOB is potentially 
susceptible to crevice corrosion if an acidic chloride-containing solution with relatively low 
concentrations of inhibitive ions contacts the waste package while it is at elevated temperatures. 
However, once the waste package cools and the solutions contacting the waste package become 
less concentrated and less aggressive, localized corrosion is not expected to initiate. 
Additional details of the model summary are given in the following sections. 
Temperature, RH, pH, [Cl-], [NO3
-] 
RH = RHthreshold 
Dry Oxidation 
(not considered for 
WP degradation analysis) 
Ecorr = Ercrev 
General 
Corrosion 
General Corrosion 
and 
Localized Corrosion 
MIC 
if RH = 90% 
Yes No 
Yes 
No 
Water Chemistry 
Evolution Derived 
from Dust Leachate 
Water Chemistry 
Evolution Derived 
from Seepage 
Figure 8-1. Schematic Representation of General Corrosion and Localized Corrosion Model of the 
Waste Package Outer Barrier 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-3 October 2004 
8.2 WASTE PACKAGE OUTER BARRIER GENERAL CORROSION MODEL 
OUTPUTS 
General corrosion of the WPOB occurs when the RH at the waste package surface is equal to or 
greater than the RH threshold for corrosion initiation (RHthreshold) (Assumption 5.1). The 
base-case general corrosion model for the WPOB (Section 6.4.3.4) is based on a temperature 
dependence of the corrosion process, represented by an activation energy using a modified 
Arrhenius relation. The model is expressed as follows: 
.. 
. 
.. 
. - + = 
15 . 333
1 1 ) ln( ) ( ln 1 T 
C R R o T (Eq. 8-1) 
where RT is the temperature-dependent general corrosion rate in nm/yr, T is absolute temperature 
in Kelvin, and Ro and C1 are constants. The temperature dependence term (C1) was obtained 
from short-term polarization resistance data for Alloy 22 specimens tested for a range of sample 
configurations, metallurgical conditions, and exposure conditions. The temperature dependence 
term is normally distributed with a mean of -3116.47 K and a standard deviation of 296.47 K. 
The activation energy was estimated to be 25.9  2.5 kJ/mol. Ro is a Weibull distribution 
(s = 8.88 nm/yr, b = 1.62, and l .= 0) that was fit to the general corrosion rate distribution derived 
from weight-loss data of the 5-year exposed crevice specimens. The 5-year data were considered 
to represent the distribution of long-term general corrosion rates of the WPOB at 60C. 
The entire variance in Ro represents variability in the general corrosion process. The general 
corrosion rate variability is applied among the modeled waste packages and local areas on the 
surface of an individual waste package. The entire variance in the temperature dependence term 
(C1) is due to uncertainty, and the uncertainty is limited to 3 standard deviations. This 
treatment of temperature dependence accounts for over 99.7 percent of the variance in this term. 
The general corrosion model developed in this report (Section 6.4.3.4) was developed using data 
in both mixed ionic environments and data from simple salt solutions including highly 
concentrated chloride brines and chloride brines containing nitrate ions. In Section 7.2, the 
general corrosion model is validated against data obtained at temperatures as high as 150C. 
Therefore, the general corrosion model should be applicable over all repository exposure 
environments. 
The general corrosion model is applied to the conditions in which a stable aqueous water film 
can exist on the waste package surface. The WPOB is considered to be subject to MIC when the 
relative humidity at the WPOB surface is equal to or greater than 90 percent (Section 6.4.5). The 
effect of MIC on general corrosion of the WPOB is represented by an enhancement factor 
applied to the general corrosion rate determined from Equation 8-1. The MIC enhancement 
factor is uniformly distributed between 1 and 2, and the entire variance of the distribution is due 
to uncertainty. 
The technical product outputs of the general corrosion model analysis are documented in the 
output DTN: MO0409MWDUGCMW.000 and summarized in Table 8-1. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-4 October 2004 
Table 8-1. Summary of General Corrosion Model Output for Waste Package Outer Barrier 
Output Uncertainty 
Output Name Output 
Description DTN Source of 
Uncertainty 
Uncertainty 
Distribution 
Characteristic 
Values 
Parameter Ro of 
temperature 
dependent 
general 
corrosion model, 
Equation 8-1. 
Weibull distribution 
(scale factor s = 
8.88 nm/yr, shape 
factor b = 1.62, 
and location factor. l 
= 0). 
(Section 6.4.3.4) 
MO0409MWDUGCMW. 
000 Measurement 
No 
uncertainty 
(entire 
variance due 
to variability) 
N/A 
Parameter C1 of 
temperature 
dependent 
general 
corrosion model, 
Equation 8-1. 
Normal distribution 
(mean 3116.47 K, 
s.d. 296.47 K). 
Limited to  3 
standard 
deviations. 
(Section 6.4.3.4) 
MO0409MWDUGCMW. 
000 Measurement Entire 
distribution N/A 
MIC 
enhancement 
factor 
Uniform distribution 
(1, 2). 
(Section 6.4.5) 
MO0409MWDUGCMW. 
000 Measurement Entire 
distribution N/A 
MIC initiation 
threshold 
Relative humidity 
threshold for MIC 
initiation. 
(Section 6.4.5) 
MO0409MWDUGCMW. 
000 N/A N/A 90% 
8.3 WASTE PACKAGE OUTER BARRIER LOCALIZED CORROSION MODEL 
OUTPUTS 
Localized corrosion of the WPOB is modeled with two model components: an initiation model 
and a propagation model (Section 6.4.4). 
8.3.1 Waste Package Outer Barrier Localized Corrosion Initiation Outputs 
Localized corrosion of the WPOB initiates when the steady-state corrosion potential (Ecorr) is 
equal to or greater than a critical potential (Ecritical), that is, .E (= Ecritical - Ecorr) = 0. As a 
conservative measure, the localized corrosion initiation model uses the crevice repassivation 
potential (Ercrev) as the critical potential. The crevice repassivation potential (Ercrev) is expressed 
as follows. 
- . + = 3 NO 
rcrev 
o
rcrev rcrev E E E (Eq. 8-2) 
where o
rcrev E is the crevice repassivation potential in the absence of inhibitive nitrate ions, and 
- . 3 NO 
rcrev E is the crevice repassivation potential changes resulting from the inhibiting effect of nitrate 
ion in solution. The potentials are in mV versus SSC. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-5 October 2004 
The crevice repassivation potential of the WPOB in the absence of inhibitive nitrate ion is 
expressed as follows: 
]) log([ ]) log([ 4 3 2 1 
- -  + + + + = Cl T a Cl a pH a T a a E o 
o
rcrev (Eq. 8-3) 
where ao, a1, a2, a3, and a4 are constants, T is the temperature (C), and ] [ - Cl is the chloride ion 
concentration in molal (moles/kg water). The value of the coefficients and their uncertainty 
(1 standard deviation) of the model parameters are = 0 a 214.089  46.880, = 1 a -3.696  0.476, 
= 2 a 25.284  5.641, = 3 a -252.181  53.912, and = 4 a 1.414  0.547. The variance of the model 
is calculated via a covariance matrix (Section 6.4.4.3), and the entire variance is due to 
uncertainty. The uncertainty of the coefficients is limited to 2 standard deviations. 
The effect of nitrate ion on the crevice repassivation potential is represented as follows: 
] [ 
] [ ] [ 3 
2 3 1 
3 
-
- 
- + + = . - 
Cl 
NO b NO b b E o 
NO 
rcrev (Eq. 8-4) 
where bo, b1 and b2 are constants, ] [ 3
- NO is the nitrate ion concentration in molal (moles/kg 
water), and other parameters are defined as before. The parameter coefficients and their 
uncertainty (1 standard deviation) are: bo = 22.589  24.113, b1 = 33.748  5.180, and b2 = 
749.745  95.491. 
The long-term steady-state corrosion potential model for the WPOB is expressed as follows: 
) 
] [ 
] [ log( ] [ 3 
4 3 2 1 -
- 
- + + + + = 
Cl 
NO c Cl c pH c T c c E o corr (Eq. 8-5) 
where corr E is the long-term steady-state corrosion potential in mV versus SSC, co, c1, c2, c3, and 
c4 are coefficients of the model parameters, and other parameters are defined as before. The 
model was evaluated by fitting it to the long-term corrosion potential data. The estimated 
regression coefficients and their uncertainty ( 1 standard deviation) are: = o c 558.283  36.156, 
= 1 c 0.677  0.413, = 2 c -65.338  2.456, = 3 c -7.616  1.581, and = 4 c 37.077  2.443. The 
variance of the model is calculated via the covariance matrix (Section 6.4.4.5), and the entire 
variance is due to uncertainty. As with the crevice repassivation potential model, the uncertainty 
of the coefficients of the corrosion potential model is limited to 2 standard deviations. 
The empirical correlations used in the waste package outer barrier localized corrosion initiation 
model for the long-term corrosion potential (Ecorr) and crevice repassivation potential (Ercrev) are 
expressed as functions of temperature, pH, chloride ion concentration, and nitrate ion 
concentration (Sections 6.4.4.3 and 6.4.4.5). Based on the range of environmental conditions in 
which the input data were obtained (Appendices V, VI, and VII) and the model validation 
activities (Sections 7.2.2 and 7.2.3), the application of the waste package outer barrier localized 
corrosion initiation model can be summarized as follows. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-6 October 2004 
Like general corrosion, localized corrosion requires the presence of a liquid water film on the 
waste package surface. To implement the waste package outer barrier localized corrosion 
initiation model, the following criteria are applied in a stepwise fashion: 
1. If aqueous brine chemistry causes the initiation of localized corrosion, then localized 
corrosion continues to propagate regardless of changes in the bulk chemical exposure 
environment. This is a conservative modeling assumption made because no detailed 
model of the chemistry evolution of the crevice solution is available at this time. 
2. If the exposure temperature exceeds 160C and a water film is present on the waste 
package surface, then localized corrosion initiates. 
Localized corrosion initiated as a result of this criterion is reevaluated in accordance 
with Criterion 3 (below) when the exposure temperature drops below 160C. 
3. If the exposure temperature exceeds 120C but is less than or equal to 160C then, 
a) If the nitrate-to-chloride ion ratio is 0.5 (or greater), no localized corrosion will 
occur, or 
b) If the nitrate-to-chloride ion ratio is less than 0.5, then localized corrosion initiates 
and continues to propagate regardless of changes in the bulk chemical exposure 
environment (Criterion 1). 
4. If the exposure temperature is greater than or equal to 20C and less than or equal 
to 120C then the empirical correlations for the long-term corrosion potential (Ecorr) 
and crevice repassivation potential (Ercrev) (Sections 6.4.4.3 and 6.4.4.5) are evaluated 
in accordance with the following implementation rules. If localized corrosion is 
determined to initiate, then localized corrosion continues to occur regardless of 
changes in the bulk chemical exposure environment (Criterion 1) 
a) If the nitrate-to-chloride ion ratio in the environment exceeds 0.5, 
then evaluate Ercrev and Ecorr at a nitrate-to-chloride ion ratio of 0.5. 
b) If the molality of chloride ion in the environment exceeds 36 molal, 
then evaluate Ercrev and Ecorr at a molality of chloride ion of 36 molal. 
If the molality of chloride ion is less than 0.001 molal, 
then evaluate Ercrev and Ecorr at a molality of chloride ion of 0.001 molal. 
c) If the molality of nitrate ion in the environment exceeds 18 molal, 
then evaluate Ercrev and Ecorr at a molality of nitrate ion of 18 molal. 
If the molality of nitrate ion is less than 0.001 molal, 
then Ercrev = o
rcrev E (i.e., the crevice repassivation potential in the absence 
of nitrate ions) and evaluate Ecorr at a molality of nitrate ion of 0.001 
molal. 
d) If the pH in the environment exceeds 10.9, 
then evaluate Ercrev and Ecorr at a pH of 10.9. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-7 October 2004 
If the pH in the environment is less than 2.8, 
then initiate localized corrosion. 
Nitrate ions inhibit localized corrosion initiation Section 6.4.4.3). In addition, carbonate and 
sulfate ions may have an inhibitive effect on localized corrosion. Therefore, because only nitrate 
ions are accounted for in the model, the results for solutions with significant amounts of other 
potentially inhibitive ions in addition to nitrate ions are conservative. The model results for the 
beneficial effects of the inhibitive ions combined with alkaline pH conditions of the typical 
carbonate-containing waters in the repository are consistent with the experimental observations 
on the immunity of Alloy 22 to localized corrosion in those waters (Section 7.2.3). 
The entire variance of the crevice corrosion initiation model (i.e., crevice repassivation potential 
model and corrosion potential model) is due to uncertainty. Variability in the crevice 
repassivation potential and corrosion potential among the waste packages to be modeled is 
represented with the temporally and spatially varying waste package temperature and water 
chemistry contacting the waste packages. In the absence of specific information regarding local 
environments on the waste package, the area affected by localized corrosion due to seepage 
water can be based on the fraction of the waste package surface that is exposed to seepage. 
Similarly, in the absence of specific information on the areal distribution of localized corrosion 
attack, the area affected by localized corrosion that may occur under deliquescent salt conditions 
can be conservatively bounded by the area exposed to dust deposition (i.e., the entire waste 
package surface). 
The crevice corrosion initiation model is used exclusively for evaluating the long-term localized 
corrosion susceptibility of the WPOB and is not intended for short-term transient behavior. 
The technical product outputs of the crevice corrosion initiation model analysis are documented 
in the output DTN: MO0409MWDULCMW.000 and summarized in Table 8-2. 
8.3.2 Localized Corrosion Propagation Model Outputs 
The localized corrosion penetration model assumes that, when it occurs, localized corrosion 
propagates at a (time-independent) constant rate (Assumption 5.4). This is a highly conservative 
assumption because it is known that the localized corrosion rate decreases with time 
(Section 6.4.4.8.2). Also, in general, localized corrosion tends to arrest or die shortly after 
initiation. 
Due to the outstanding corrosion resistance of Alloy 22, very little data exist for localized 
corrosion under the conditions expected in the repository. The literature data for localized 
corrosion of relevant alloys that were considered for the current localized penetration rate model 
are for extremely corrosive conditions not expected in the repository. Those extreme penetration 
rates found in the literature were used to bound localized corrosion rates of Alloy 22 under 
repository conditions. 
The technical product outputs of the crevice corrosion propagation model analysis are 
documented in the output DTN: MO0409MWDULCMW.000 and summarized in Table 8-2. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-8 October 2004 
Table 8-2. Summary of Localized Corrosion Model Output for Waste Package Outer Barrier 
Output Uncertainty 
Output Name Output 
Description DTN Source of 
Uncertainty 
Uncertainty 
Distribution 
(if 
applicable) 
Characteristic 
Values (if 
applicable) 
5 coefficients of 
crevice 
repassivation 
potential model 
without nitrate 
ions, Equation 
8-3 
Mean ao = 214.089 
Mean a1 = -3.696 
Mean a2 = 25.284 
Mean a3 = -252.181 
Mean a4 = 1.414 
Covariance matrix 
given in Equation 
6-33. Coefficient 
distributions are 
limited to 2 
standard 
deviations. 
MO0409MWDULCMW 
.000 Measurement Entire 
distribution N/A 
3 coefficients of 
crevice 
repassivation 
potential change 
model due to 
nitrate ions, 
Equation 8-4 
bo = 22.589 
b1 = 33.748 
b2 = 749.745 
MO0409MWDULCMW 
.000 N/A N/A N/A 
5 coefficients of 
long-term 
corrosion 
potential model, 
Equation 8-5 
Mean co = 558.283 
Mean c1 = 0.677 
Mean c2 = -65.338 
Mean c3 = -7.616 
Mean c4 = 37.077 
Covariance matrix 
given in Equation 
6-37. Coefficient 
distributions are 
limited to 2 
standard 
deviations. 
MO0409MWDULCMW 
.000 Measurement Entire 
distribution N/A 
Crevice 
corrosion 
propagation rate 
(Table 6-8) 
Log-uniform 
distribution, 
0th percentile = 
12.7 m/yr 
50th percentile = 
127 m/yr 
100th percentile = 
1270 m/yr 
MO0409MWDULCMW 
.000 
Conceptual 
model, data 
Entire 
distribution N/A 
8.4 YUCCA MOUNTAIN REVIEW PLAN ACCEPTANCE CRITERIA 
The Yucca Mountain Review Plan (YMRP) contains Acceptance Criteria (AC) intended to 
establish the basis for the review of the material contained in the License Application. As this 
report serves, in part, as the basis for the License Application, it is important to show how the 
information contained herein addresses each of the applicable YMRP Acceptance Criteria. 
The YMRP Acceptance Criteria applicable to this report are identified in Technical Work Plan 
for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-9 October 2004 
(BSC 2004 [DIRS 171583], Table 3-1). For each applicable criterion, the criterion is quoted in 
italics, followed by pointers to where within the report the information addressing the criterion 
can be found. In some cases, the criterion is only partially addressed in this report. 
A demonstration of full compliance requires a review of multiple reports. 
8.4.1 System Description and Demonstration of Multiple Barriers (NRC 2003 
[DIRS 163274], Section 2.2.1.1.3) 
The waste package meets the definition of a barrier in 10 CFR 63.2 [DIRS 156605]. 
Acceptance Criterion 1 - Identification of Barriers is Adequate. 
Barriers relied on to achieve compliance with 10 CFR 63.113(b), as 
demonstrated in the total system performance assessment, are adequately 
identified, and are clearly linked to their capability. The barriers identified 
include at least one from the engineered system and one from the natural system. 
The system that this model report addresses is the engineered barrier system (EBS), and the 
barrier that this model report addresses is the waste package (WP). The waste package barrier 
functions are addressed throughout this report and more specifically in Sections 1.3 and 6.3. 
This report does not address natural systems. 
Acceptance Criterion 2 - Description of Barrier Capability is Acceptable. 
The capability of the identified barriers to prevent or substantially reduce the rate 
of movement of water or radionuclides from the Yucca Mountain repository to the 
accessible environment, or prevent the release or substantially reduce the release 
rate of radionuclides from the waste is adequately identified and described: 
(1) The information on the time period over which each barrier performs its 
intended function, including any changes during the compliance period, is 
provided; 
(2) The uncertainty associated with barrier capabilities is adequately described; 
(3) The described capabilities are consistent with the results from the total system 
performance assessment; and 
(4) The described capabilities are consistent with the definition of a barrier at 10 
CFR 63.2. 
The waste package barrier contributes to waste isolation by keeping water away from the waste 
for its lifetime and, when breached, by reducing the contact of water with the waste and 
radionuclide release rate from the waste. The waste package barrier functions are addressed 
throughout this report and more specifically in Sections 1.3 and 6.3. The models to describe 
these capabilities are summarized in Sections 8.1, 8.2, and 8.3. Uncertainties associated with the 
waste package barriers capabilities are also summarized in Sections 8.1, 8.2, and 8.3. The waste 
package degradation models and their associated uncertainties are consistent with the models 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-10 October 2004 
used in TSPA-LA. The waste package meets the definition of a barrier in 10 CFR 63.2 
[DIRS 156605]. 
Acceptance Criterion 3 - Technical Basis for Barrier Capability Is Adequately Presented. 
The technical bases are consistent with the technical basis for the performance 
assessment. The technical basis for assertions of barrier capability is commensurate 
with the importance of each barriers capability and the associated uncertainties. 
The technical basis for the barrier capability is documented in Sections 6.4.2, 6.4.3, 6.4.4, 6.4.5, 
and 6.4.6. Section 6.4.3 documents the technical basis for the general corrosion model, 
Section 6.4.4 for the localized corrosion model, and Section 6.4.5 for the microbially influenced 
corrosion (MIC) model. Section 6.4.2 documents the technical basis that the degradation of the 
WPOB by dry oxidation is negligible under the repository thermal conditions, and, therefore, is 
not included in the waste package degradation analysis. Section 6.4.6 documents the technical 
basis that aging and phase instability of Alloy 22 will not significantly affect the corrosion 
performance of the WPOB in the repository and, therefore, is not included in the waste package 
degradation analysis. The technical bases are consistent with the corresponding technical bases 
in performance assessment because the waste package degradation models are used as input to 
TSPA-LA. 
8.4.2 Degradation of Engineered Barriers (NRC 2003 [DIRS 163274], Section 2.2.1.3.1.3) 
Acceptance Criterion 1  System Description and Model Integration are Adequate 
(1) TSPA adequately incorporates important design features, physical phenomena 
and couplings and uses consistent assumptions throughout the degradation of 
engineered barriers abstraction process. 
(2) Abstraction uses assumptions, technical bases, data and models that are 
appropriate and consistent with [those used] in other related abstractions. 
(3) The descriptions of the engineered barriers, design features, degradation 
processes, physical phenomena, and couplings that may affect the degradation of 
the engineered barriers are adequate. 
(4) Initial and boundary conditions are propagated consistently throughout the 
abstraction process. 
(5) Sufficient technical basis for the inclusion [and exclusion] of FEPs are 
provided; 
(6) Adequate technical bases are provided, for selecting the design criteria, that 
mitigate any potential impact of in-package criticality on repository performance, 
including considering all features, events, and processes that may increase the 
reactivity of the system inside the waste package. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-11 October 2004 
(7) Guidance in NUREG 1297 and NUREG 1298 [re: Expert Elicitation] are 
followed. 
The physical phenomena, factors (including design features, environmental factors, and their 
coupling) are described in Section 6.3 as part of the conceptual model discussion for general and 
localized corrosion of the WPOB. The models developed in this report are adequately 
incorporated into TSPA-LA. Integration of the submodels for WPOB corrosion degradation 
analysis (general corrosion model, MIC model, crevice repassivation potential model, corrosion 
potential model, and localized corrosion penetration model) is also described in Section 6.3. 
Throughout this report, the analyses use assumptions, technical bases, input data and models that 
appropriately reflect the design of the waste package and the humid air and groundwater media 
that may come in contact with the waste package. Assumptions used in this report are addressed 
in Section 5. The data, technical bases and models are addressed in Sections 4.1 and 6. This 
information is used in a manner that is consistent with other abstractions of processes associated 
with the degradation of the waste package barrier. Initial and boundary conditions are 
propagated consistently throughout the abstraction process as described in Sections 1.2, 6, and 8 
where the waste package degradation models and ranges of application are discussed. 
The features, events, and processes (FEPs) treated in this report are identified in Section 6.2. 
Sufficient technical basis for the inclusion of FEPs (Table 6-1) are provided in Section 6.3 as 
part of the conceptual model discussion for general and localized corrosion of the WPOB and 
Sections 6.4.3, 6.4.4, and 6.4.5. Section 6.4.3 documents the technical basis for inclusion of 
general corrosion, Section 6.4.4 for inclusion of localized corrosion, and Section 6.4.5 for 
inclusion of microbially influenced corrosion (MIC). 
Those sections of the acceptance criterion that relate to the selection of design criteria are not 
applicable to this report because design criteria are not selected in this report. Those sections of 
the acceptance criterion that relate to the use of expert elicitation are not applicable to this report 
because expert elicitation was not used in this report. 
Acceptance Criterion 2  Data Are Sufficient for Model Justification 
(1) Parameters used to evaluate the degradation of EBS are adequately justified 
and describes how the data were used, interpreted, and appropriately synthesized 
into the parameters. 
(2) Sufficient data have been collected to establish initial and boundary 
conditions; 
(3) Data on the degradation of the engineered barriers are based on laboratory 
measurements, site-specific field measurements, industrial and/or natural analogs 
and tests designed to replicate anticipated conditions. As appropriate, sensitivity 
or uncertainty analyses are provided and are shown to be adequate to determine 
the possible need for additional data. 
(4) Degradation models for the applicable processes are adequate. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-12 October 2004 
Section 4.1.1 documents the input data and their use in the model analysis. Appendices II to VIII 
document the numerical values of the data used in the model development and analysis. The 
input data and parameters used to evaluate the performance of the waste package were obtained 
from controlled sources and were adequately justified for their intended use (Section 4.1.1). 
Section 4.1.1 and Appendices II to VIII show that sufficient data have been collected to establish 
initial and boundary conditions for the models developed in this report. The data used was based 
on laboratory measurements under testing conditions designed to replicate anticipated repository 
exposure conditions. Degradation models for the processes relevant to degradation of the waste 
package were given appropriate consideration (Section 6) and were found to be adequate for 
their intended use (Section 7). 
Acceptance Criterion 3  Data Uncertainty is Characterized and Propagated through the 
Model Abstraction 
(1) Models use parameter values, assumed ranges, probability distributions 
and/or bounding assumptions that are technically defensible, reasonably account 
for uncertainties and variabilities, and do not result in under-representation of 
the risk estimate. 
(2) Appropriate parameters, based on techniques that may include laboratory 
experiments, field measurements, industrial analogs and process-level modeling 
studies conducted under conditions relevant to the range of environmental 
conditions within the waste package emplacement drifts are used. 
(3) Assumed range of values and probability distributions for parameters used in 
conceptual and process-level models are not likely to underestimate the actual 
degradation and failure of engineered barriers. 
(4) Appropriate methods were used for nondestructive examination of fabricated 
engineered barriers to assess the type, size, and location of fabrication defects 
that may lead to premature failure as a result of rapidly initiated engineered 
barrier degradation. Specify and justify the allowable distribution of fabrication 
defects in the engineered barriers, and assesses the effects of defects that cannot 
be detected on the performance of the engineered barriers. 
(5) Where sufficient data do not exist, the definition of parameter values and 
conceptual models is based on appropriate use of other sources, such as expert 
elicitation. 
Each of the models developed in this report use parameter values, assumed ranges, probability 
distributions or technically defensible bounding assumptions reasonably account for 
uncertainties and variabilities, and do not result in under-representation of the risk estimate. The 
various models developed in this report use data and parameters developed based on laboratory 
experiments (Section 4.1.1 and Appendices II to VIII) or bounding assumptions, or both, that are 
technically defensible and reasonably account for uncertainties and variabilities. The effects of 
data uncertainties on the parameter ranges and uncertainty distributions in the models developed 
in this report are discussed in Sections 6.4.3, 6.4.4, and 6.4.5. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-13 October 2004 
Section 6.4.3 discusses the effects of data uncertainties on the general corrosion model 
developed in this report. Uncertainties in the data used for the general corrosion model analysis 
(5-year weight-loss measurements and short-term polarization resistance measurements) were 
characterized and quantified, and propagated through the general corrosion model abstraction 
(Section 6.4.3). The treatment of general corrosion in this report is not likely to under-represent 
the risk estimate from general corrosion. For example, the general corrosion model uses (at a 
given temperature) a constant rate of uniform penetration (Assumption 5.2) based on laboratory 
weight-loss measurements from samples with creviced geometries exposed for five years in 
repository relevant solutions. This assumption is conservative because the general corrosion rate 
of alloys decreases with time (Figure 7-1). Therefore, it is not likely that the general corrosion 
model developed in this report will under-represent the risk estimate from general corrosion. 
Section 6.4.4 discusses the effects of data uncertainties on the localized corrosion model 
developed in this report. Uncertainties in the data used for the localized corrosion model analysis 
(crevice repassivation potentials, and long-term steady-state corrosion potentials) were 
characterized and quantified, and propagated through the localized corrosion model abstraction 
(Section 6.4.4). A conservative bounding approach, based on the literature data for Alloy 22 in 
highly corrosive environments, was used to capture the uncertainty in the localized corrosion rate 
of Alloy 22 (Section 6.4.4). The treatment of localized corrosion in this report is not likely to 
under-represent the risk estimate from localized corrosion. For example, the localized corrosion 
model developed in this report uses a localized corrosion initiation criterion based on crevice 
corrosion (Assumption 5.3). This treatment is conservative because initiation thresholds (in 
terms of exposure parameters such as temperature and solution chemistry) for crevice corrosion 
are lower than for pitting (another type of localized corrosion attacking boldly exposed surfaces). 
Furthermore, the localized corrosion model uses a localized corrosion rate, which is a time 
independent constant rate (Assumption 5.4). This assumption is conservative because localized 
corrosion penetration rates decrease with time. Therefore, it is not likely that the localized 
corrosion model developed in this report will underrepresent the risk estimate from localized 
corrosion. 
Section 6.4.5 discusses the effects of data uncertainties on the microbially influenced corrosion 
(MIC) model developed in this report. The treatment of MIC in this report is not likely to underrepresent 
the risk estimate from MIC. The MIC RH initiation threshold is a reasonable 
representation of the conditions necessary for microbes to be active in the repository 
environment. Relevant data were analyzed to determine the effects of microbial action on 
corrosion rates. Given that the effect of MIC is a multiplier on the general corrosion rate 
(discussed above as a conservative representation), the treatment of MIC in this report is unlikely 
to under-represent the risk estimate from MIC. 
Those sections of the acceptance criterion that relate to nondestructive examination of fabricated 
engineered barriers are not applicable to this report because no analyses of nondestructive 
examination of fabricated engineered barriers were analyzed in this report. Those sections of the 
acceptance criterion that relate to the use of other sources, such as expert elicitation, are not 
applicable to this report because no other sources were used in the creation of this report. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-14 October 2004 
Acceptance Criterion 4  Model Uncertainty is Characterized and Propagated Through the 
Model Abstraction 
(1) Alternative modeling approaches of features, events, and processes are 
considered and are consistent with available data and current scientific 
understanding and the results and limitations are appropriately considered in the 
abstraction. 
(2) Consideration of conceptual model uncertainty is consistent with available 
site characterization data, laboratory experiments,  and the treatment of 
uncertainty does not result in under-estimation of the risk estimate. 
(3) Alternative modeling approaches, consistent with available data and current 
scientific understanding, are used and the modeling results are evaluated using 
tests and analyses that are sensitive to the processes modeled. 
The uncertainties in the general corrosion and localized corrosion models are addressed through 
the qualitative assessment of alternative conceptual models (Sections 6.4.3.5 and 6.4.4.8), which 
were consistent with available data and current scientific understanding. Although these 
alternative models are not used in TSPA-LA, they are used, where applicable, for model 
validation in Section 7. Consideration of uncertainties of the models developed in this report is 
an integral part of the model development and validation. Conceptual model uncertainty is 
consistent with the information that has been developed through laboratory experiments 
(Section 4.1.1 and Appendices II to VIII). As discussed in Acceptance Criterion 3, the treatment 
of uncertainty is unlikely to result in under-representation of the risk estimates. 
Acceptance Criterion 5  Model Abstraction Output Is Supported By Objective 
Comparisons 
(1) Models implemented in this total system performance assessment abstraction 
provide results consistent with output from detailed process-level models and or 
empirical observations (laboratory and field testing, and/or natural analogs). 
(2) Numerical corrosion models used to calculate the lifetimes of the engineered 
barriers are adequate representations, considering the associated uncertainties in 
the expected long-term behaviors, the range of conditions (including residual 
stresses), and the variability in engineered barrier fabrication processes 
(including welding); 
(3) Evidence is sufficient to show that models will not underestimate the actual 
degradation and failure of engineered barriers. 
(4) Mathematical degradation models are based on the same environmental 
parameters, material factors, assumptions and approximations shown to be 
appropriate for closely analogous applications. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-15 October 2004 
(5) Accepted and well documented procedures are used to construct and test the 
numerical models that simulate the EBS chemical environment and degradation 
of engineered barriers 
(6) Sensitivity analyses or bounding analyses are provided to support the 
abstraction of degradation of engineered barriers that cover ranges consistent 
with the site data, field or laboratory experiments and tests, and industrial 
analogs. 
The results of waste package degradation models developed in this report are implemented in the 
TSPA-LA as specified in this report, therefore the TSPA-LA model results are consistent with 
output from this report. The models developed in this report were compared with laboratory data 
used to develop the models in Section 6. The models developed in this report were compared 
with laboratory and/or literature data not used in model development in Section 7. As discussed 
in Acceptance Criterion 3, there is sufficient evidence that the models developed in this report 
will not underestimate the actual degradation and failure of engineered barriers. The 
mathematical models developed in this report were based on data collected using materials 
(Alloy 22) and exposure environments relevant to those expected in the repository. The models 
developed in this report were constructed following the accepted and well-documented 
AP-SIII.10Q, Models. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 8-16 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 9-1 October 2004 
9. INPUTS AND REFERENCES 
9.1 DOCUMENTS CITED 
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159836 Brossia, C.S.; Browning, L.; Dunn, D.S.; Moghissi, O.C.; Pensado, O.; and Yang, L. 
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169860 BSC 2004. Engineered Barrier System: Physical and Chemical Environment Model. 
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A.G.; Dewald, A.T.; Lee, M.J.; and Hill, M.R. 2002. Mitigation of Tensile Weld 
Stresses in Alloy 22 Using Laser Peening. UCRL-ID-151055. Livermore, California: 
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Processes for Alloy 22 as a High-Level Nuclear Waste Container Material. 
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164495 Dunn, D.S.; Cragnolino, G.A.; and Sridhar, N. 2000. An Electrochemical Approach 
to Predicting Long-Term Localized Corrosion of Corrosion-Resistant High-Level 
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161204 LL020711612251.017. Open Circuit Potential Tests. Submittal date: 10/11/2002. 
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163455 LL030309512251.042. Low Temperature Operating Mode Electrochemical Test 
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04/08/2003. 
163469 LL030406412251.045. Transmission Electron Microscopy (TEM) Images of Oxide 
Film on Air-Oxidized Alloy22 (UNS N06022) Samples Aged at 550C. Submittal 
date: 04/11/2003. 
163462 LL030409512251.051. Electrochemical Analysis of Alloy 22 - CaCl2 Data at Various 
Temperatures, Surface Conditions, and Electrolyte Solutions. Submittal date: 
05/23/2003. 
164185 LL030409812251.054. Electrochemical Data of Alloy 22 in CaCl2 Solutions-Effect 
of Nitrate. Submittal date: 06/26/2003. 
163712 LL030412512251.057. LTCTF Corrosion Rate Calculations for Five-Year Exposed 
Alloy C22 Specimens Cleaned Under TIP-CM-51. Submittal date: 05/28/2003. 
163456 LL030502212251.063. Corrosion Potential, Polarization Resistance, and Cyclic 
Polarization in Several Environments at Several Temperatures for Alloy 22. 
Submittal date: 05/20/2003. 
164184 LL030703723121.031. Conversion of Corrosion Testing Solutions from Molar to 
Molal Concentration Units. Submittal date: 07/10/2003. 
170502 LL031001023121.035. Conversion of Corrosion Testing Solutions from Molar to 
Molal Concentration Units (II). Submittal date: 04/23/2004. 
170221 LL040303612251.078. Microbiology Influenced Corrosion (MIC) Effects on 
Microcosm-Incubated Alloy 22. Submittal date: 03/29/2004. 
170283 LL040402112251.083. Corrosion Potential and Critical Potential for Alloy 22. 
Submittal date: 05/19/2004. 
170097 LL040402212251.084. Critical and Corrosion Potential for Alloy 22 (N06022). 
Submittal date: 05/26/2004. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 9-14 October 2004 
170222 LL040402912251.085. Microbiologically Induced Corrosion (MIC) Linear 
Polarization Corrosion Rate of Alloy 22 Weldments for Sterile and Non-Sterile 
Coupons. Submittal date: 04/20/2004. 
171362 LL040803112251.117. Target Compositions of Aqueous Solutions Used for 
Corrosion Testing. Submittal date: 08/14/2004. 
138343 LL991203505924.094. Approach and Supporting Data for MIC Modeling. Submittal 
date: 12/13/1999. 
170760 MO0407SEPFEPLA.000. LA FEP List. Submittal date: 07/20/2004. 
9.4 OUTPUT DATA, LISTED BY DATA TRACKING NUMBER 
MO0409MWDULCMW.000. Updated Localized Corrosion Model of the Waste 
Package Outer Barrier. Submittal date: 09/17/2004. 
MO0409MWDUGCMW.000. Updated General Corrosion Model of the Waste 
Package Outer Barrier. Submittal date: 09/17/2004. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 I-1 October 2004 
APPENDIX I 
SUMMARY OF THE ELECTROCHEMICAL CORROSION TEST PROCEDURES TO 
GENERATE INPUT DATA FOR ANALYSES AND MODELS IN THIS REPORT 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 I-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 I-3 October 2004 
I. SUMMARY OF THE ELECTROCHEMICAL CORROSION TEST PROCEDURES 
TO GENERATE INPUT DATA FOR ANALYSES AND MODELS IN THIS REPORT 
This appendix summarizes the electrochemical corrosion tests that were employed to generate 
input data for the analyses and models of the WPOB documented in this report. The typical 
sequence for electrochemical testing was as follows: 
 Grind and polish the testing specimen to eliminate residual effects of fabrication. The 
surface finishing of the test specimens corresponded to abrasive 600-grit paper. This 
grinding was done within one hour prior of immersing the test specimen in the 
electrolyte solution. The testing cell is as described in ASTM G 5-94 (1994 
[DIRS 117479]). 
 After immersion of the specimen in the electrolyte solution of interest, the free corrosion 
potential of the specimen was monitored for 24 hours. The value of potential at the end 
of this 24-hour period was called the corrosion potential (Ecorr). In a few cases, the 
corrosion potential was monitored for shorter times (1 or 2 hours). 
 After this 24-hour period, at least three polarization resistance (PR) tests were carried 
out according to ASTM G 59-97. The value of the slope of the polarization resistance 
curve (Rp) was used to calculate the general corrosion rate (ASTM G 59-97 1998 
[DIRS 163907] and G 102-89 1989 [DIRS 163908]). 
 After the polarization resistance tests, one cyclic potentiodynamic polarization (CPP) 
test was carried out according to ASTM G 61-86 (1987 [DIRS 127897]). The cyclic 
polarization curve yielded the value of the critical potential for localized corrosion of the 
WPOB. 
Details of the tests are provided in the corresponding Scientific Notebooks cited in the Data 
Tracking Numbers (DTNs) of the input data documented in Section 4.1.1. 
I.1 DETERMINATION OF CORROSION RATES FROM POLARIZATION 
RESISTANCE TESTS 
The polarization resistance test was carried out using the default set-up of the potentiostat and its 
software. The test consists of ramping the potential at a rate of 0.167 mV/sec (0.6 V/hr) 
(consistent with ASTM G 59-97 1998 [DIRS 163907]) while recording the current applied to the 
specimen. The potential scan was started 20 mV below Ecorr and finished 20 mV above Ecorr. The 
value of Ecorr chosen by the instrument for this scan is the Ecorr value 10 seconds before the scan 
was started (default set up). The resulting data consists of applied values of potential (E) and 
applied values of current (I). If these data are plotted E versus I on a linear scale, a more or less 
straight line is obtained. The slope of this line is called the resistance to polarization or Rp. 
ASTM G 59-97 (1998 [DIRS 163907]) and ASTM G 102-89 (1989 [DIRS 163908]) explain the 
reasoning behind the use of this slope in calculating instantaneous corrosion rates. To calculate 
the corrosion rates, besides the slope Rp, several other data are needed. These data include, 
(1) the exposed area of the specimen, (2) the values of the Tafel slopes, (3) the Faraday constant 
(charge passed by one mole of electrons), (4) the value of the equivalent weight of the tested 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 I-4 October 2004 
alloy and (5) the density of the tested alloy. The last two data are needed to use the Faraday 
conversion of current to penetration rate. 
The calculation performed in the current report was done considering the following. 
 The exposed area of the specimens: For multiple crevice assembly (MCA) samples, the 
area changed according to the length of the immersed specimen in the electrolyte 
solution. The exposed area of samples with other geometries (e.g., prism, rod and disc) 
also varies from sample to sample. 
 The cathodic and anodic Tafel slopes are both equal to 0.12 V/decade. That is, it is 
considered that it takes 0.12 V to change the current on the specimen by one order of 
magnitude. This is a default setting of the Gamry software. 
 The charge passed by one mole of electrons is 96,486 C (Lide 1991 [DIRS 131202], 
Table 1, p. I-1). 
 The equivalent weight (EW) for Alloy 22 (N06022) is calculated considering that the 
alloy dissolves stoichiometrically, and it depends on the valence for the dissolved 
elements. The value used was taken from Table 1 of ASTM G 102 (1989 
[DIRS 163908]), third oxidation state. That is EW = 23.28. 
 The density of Alloy 22 (N06022) is 8.69 g/cm (Haynes International 1997 
[DIRS 100896], p. 13). 
The value of Rp in ohm-cm2 can be calculated by plotting the curve and estimating its slope. This 
can be done manually. The Gamry software has a program to calculate the corrosion rate directly 
from the acquired data. The calculation of Rp (which is used to calculate the corrosion rate) can 
be accomplished by using the entire range of potentials (40 mV) or a specific predetermined 
range around the potential for zero applied current (Ecorr). Since in most environments the plots 
of potential versus current in the linear scale were not straight (linear), a smaller range of 
potential around Ecorr was chosen (ASTM G 3-89 1989 [DIRS 138911]). The range chosen in our 
calculations was 10 mV below Ecorr and 10 mV above Ecorr. To perform the calculation, the Ecorr 
at 10 seconds before the test was selected and from this value 10 mV were subtracted (Es = Ecorr 
 10 mV). This potential was the starting potential for the calculation range (Es). Similarly the 
finish potential point (Ef) was chosen as Ef = Ecorr + 10 mV. 
p 
corr R
B i 6 10 = (Eq. I-1) 
where icorr is the corrosion current density in A/cm, and Rp is the slope in ohm-cm. B is the 
Stern-Geary coefficient and is related to the anodic and cathodic Tafel slopes as follows 
(ASTM G-59-97 1998 [DIRS 163907]). 
) ( 303 . 2 c a 
c a 
b b
b b B 
+ 
 = (Eq. I-2) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 I-5 October 2004 
where ba and bc are the anodic and cathodic Tafel slopes respectively, which are both considered 
to be 0.12 V. The corrosion rate is then calculated as 
. 
 EW i year m CR corr  = 27 . 3 ) / ( (Eq. I-3) 
where EW is the equivalent weight of the alloy (23.28 for N06022) (ASTM G 102-89 1989 
[DIRS 163908], Table 1), and . is the density of the alloy (8.69 g/cm for N06022) (Haynes 
International 1997 [DIRS 100896], p. 13). 
I.2 DETERMINATION OF THE CRITICAL POTENTIAL OR REPASSIVATION 
POTENTIAL FROM THE CYCLIC POLARIZATION TESTS 
In the cyclic polarization tests, the specimen was polarized at a constant scan rate, while the 
applied current was recorded. The potential scan rate was 0.167 mV/sec or 0.6 V/hr starting at a 
potential of 150 mV below Ecorr and continuing until the current density reached a value of 
5 mA/cm (ASTM G 61-86 1987 [DIRS 127897]). At this point the scan rate was reversed, and 
the test was terminated at the original Ecorr or before. It may also be terminated manually after 
the reversing curve intersects the forward curve. 
Ambient Vision 
Weld affected Zone 
~ 1 inch 
Pre-weld Plate gap 
~ 0.5 inch 
0.276 inch 
internal 
diameter 
0.787 inch 
external diameter 
Schematic of MCA Crevice Sample with Weld  Top View (not to scale) 
Figure I-1. Schematic of An As-Welded Multiple Crevice Assembly (MCA) Sample 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 I-6 October 2004 
Teflon 
Insert 
Serrated Ceramic 
Crevice Washer 
Ti Grade 2 Bolt 
Ti Grade 2 
Washer 
Ti Grade 2 Nut 
Crevice Gap 
Applied Torque = 70 inch-lb 
Source: Kehler et al. 2001 [DIRS 162231]. 
Figure I-2. Schematic of a Multiple Crevice Assembly (MCA) Sample 
- Blue: Immersed 
Surface Area 
- Black: Occluded Area 
Schematic of Exposed Surface Area of MCA 
Figure I-3. Schematic Showing the Exposed Surface Area of a Multiple Crevice Assembly (MCA) 
Sample During Electrochemical Testing 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 II-1 October 2004 
APPENDIX II 
GENERAL CORROSION RATES OF ALLOY 22 CREVICE SAMPLES BASED ON 
WEIGHT-LOSS MEASUREMENTS AFTER 5-YEAR EXPOSURE IN THE LONGTERM 
CORROSION TEST FACILITY 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 II-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 II-3 October 2004 
II. GENERAL CORROSION RATES OF ALLOY 22 CREVICE SAMPLES BASED ON WEIGHT-LOSS 
MEASUREMENTS AFTER 5-YEAR EXPOSURE IN THE LONG-TERM CORROSION TEST FACILITY 
Sample ID 
Length 
(in.) 
Width 
(in.) 
Thickness 
(in.) 
Initial 
Weight 
(g) 
Sample 
Condition a) Exposure Environment 
Final 
Weight (g) 
Weight 
Loss (g) 
Exposed 
Time 
(hours) 
Surface Area 
(cm2) 
Corrosion 
Rate (nm/yr) c) 
DCA019 2.0120 2.0120 0.1145 64.6723 MA Crevice SAW Vapor Phase 60C 64.6698 0.0025 46,296 57.917 9.41 
DCA020 2.0155 2.0150 0.1175 66.3190 MA Crevice SAW Vapor Phase 60C 66.3168 0.0022 46,296 58.270 8.23 
DCA021 2.0105 2.0125 0.1165 65.4770 MA Crevice SAW Vapor Phase 60C 65.4747 0.0023 46,296 58.006 8.64 
DCA022 2.0135 2.0135 0.1175 65.8096 MA Crevice SAW Aqueous Phase 60C 65.8079 0.0017 46,296 58.174 6.37 
DCA023 2.0135 2.0115 0.1165 65.5176 MA Crevice SAW Aqueous Phase 60C 65.5150 0.0026 46,296 58.061 9.76 
DCA024 2.0125 2.0110 0.1165 64.9706 MA Crevice SAW Aqueous Phase 60C 64.9646 0.0060 46,296 58.020 22.52 
DCA049 2.0175 2.0120 0.1180 66.0889 MA Crevice SAW Vapor Phase 90C 66.0857 0.0032 45,960 58.272 12.05 
DCA050 2.0170 2.0160 0.1175 66.1281 MA Crevice SAW Vapor Phase 90C 66.1235 0.0046 45,960 58.339 17.30 
DCA051 2.0160 2.0155 0.1205 67.2585 MA Crevice SAW Vapor Phase 90C 67.2543 0.0042 45,960 58.473 15.76 
DCA052 2.0135 2.0090 0.1015 57.4226 MA Crevice SAW Aqueous Phase 90C 57.4211 0.0015 45,960 57.119 5.77 
DCA053 2.0140 2.0140 0.1160 65.4009 MA Crevice SAW Aqueous Phase 90C 65.3987 0.0022 45,960 58.114 8.31 
DCA054 2.0160 2.0140 0.1170 65.8061 MA Crevice SAW Aqueous Phase 90C 65.8044 0.0017 45,960 58.227 6.41 
DCA079 2.0135 2.0120 0.1160 65.3198 MA Crevice SCW Vapor Phase 60C 65.3190 0.0008 45,456 58.045 3.06 
DCA080 2.0160 2.0155 0.1000 57.5590 MA Crevice SCW Vapor Phase 60C 57.5582 0.0008 45,456 57.277 3.11 
DCA081 2.0155 2.0155 0.1160 65.5190 MA Crevice SCW Vapor Phase 60C 65.5179 0.0011 45,456 58.197 4.20 
DCA082 2.0160 2.0145 0.1170 65.7599 MA Crevice SCW Aqueous Phase 60C 65.7574 0.0025 45,456 58.241 9.53 
DCA083 2.0190 2.0145 0.1160 65.2679 MA Crevice SCW Aqueous Phase 60C 65.2660 0.0019 45,456 58.265 7.24 
DCA084 2.0150 2.0100 0.1030 59.6044 MA Crevice SCW Aqueous Phase 60C 59.6006 0.0038 45,456 57.274 14.72 
DCA109 2.0110 2.0155 0.1160 65.2077 MA Crevice SCW Vapor Phase 90C 65.2062 0.0015 44,832 58.073 5.82 
DCA110 2.0130 2.0145 0.1165 65.2979 MA Crevice SCW Vapor Phase 90C 65.2949 0.0030 44,832 58.129 11.61 
DCA111 2.0165 2.0165 0.1190 66.6259 MA Crevice SCW Vapor Phase 90C 66.6244 0.0015 44,832 58.427 5.78 
DCA112 2.0150 2.0115 0.1120 63.2332 MA Crevice SCW Aqueous Phase 90C 63.2324 0.0008 44,832 57.840 3.12 
DCA113 2.0105 2.0150 0.1065 60.1129 MA Crevice SCW Aqueous Phase 90C 60.1102 0.0027 44,832 57.492 10.57 
DCA114 2.0175 2.0125 0.1080 60.9881 MA Crevice SCW Aqueous Phase 90C 60.9853 0.0028 44,832 57.702 10.92 
DCA139 2.0170 2.0105 0.1110 62.0138 MA Crevice SDW Vapor Phase 60C 62.0126 0.0012 44,448 57.809 4.72 
DCA140 2.0140 2.0120 0.1100 61.6079 MA Crevice SDW Vapor Phase 60C 61.6070 0.0009 44,448 57.709 3.54 
DCA141 2.0180 2.0160 0.1110 62.3601 MA Crevice SDW Vapor Phase 60C 62.3594 0.0007 44,448 57.987 2.75 
DCA142 2.0150 2.0115 0.1120 62.7895 MA Crevice SDW Aqueous Phase 60C 62.7879 0.0016 44,448 57.840 6.28 
DCA143 2.0120 2.0120 0.1115 62.4663 MA Crevice SDW Aqueous Phase 60C 62.4648 0.0015 44,448 57.742 5.90 
DCA144 2.0100 2.0125 0.1100 61.4272 MA Crevice SDW Aqueous Phase 60C 61.4251 0.0021 44,448 57.614 8.27 
DCA175 2.0170 2.0120 0.0900 49.9140 MA Crevice SDW Vapor Phase 90C 49.9138 0.0002 43,488 56.625 0.83 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 II-4 October 2004 
Sample ID 
Length 
(in.) 
Width 
(in.) 
Thickness 
(in.) 
Initial 
Weight 
(g) 
Sample 
Condition a) Exposure Environment 
Final 
Weight (g) 
Weight 
Loss (g) 
Exposed 
Time 
(hours) 
Surface Area 
(cm2) 
Corrosion 
Rate (nm/yr) c) 
DCA176 2.0075 2.0090 0.1045 58.6401 MA Crevice SDW Vapor Phase 90C 58.6399 0.0002 43488 57.130 0.82 
DCA177 b) 2.0125 2.0100 0.1100 61.7156 MA Crevice SDW Vapor Phase 90C 61.7040 0.0116 43,488 57.614 46.68 
DCA178 2.0145 2.0120 0.1140 63.9838 MA Crevice SDW Aqueous Phase 90C 63.9817 0.0021 43,488 57.956 8.41 
DCA179 2.0125 2.0100 0.1075 60.3046 MA Crevice SDW Aqueous Phase 90C 60.3033 0.0013 43,488 57.468 5.25 
DCA180 2.0135 2.0065 0.1020 57.4820 MA Crevice SDW Aqueous Phase 90C 57.4807 0.0013 43,488 57.080 5.29 
DCB019 2.0010 1.9975 0.0810 45.0056 ASW Crevice SAW Vapor Phase 60C 45.0030 0.0026 46,296 55.279 10.25 
DCB020 1.9945 2.0010 0.1035 55.5235 ASW Crevice SAW Vapor Phase 60C 55.5217 0.0018 46,296 56.501 6.94 
DCB022 2.0030 2.0000 0.0900 49.1369 ASW Crevice SAW Aqueous Phase 60C 49.1354 0.0015 46,296 55.922 5.85 
DCB023 2.0050 2.0110 0.1010 56.3136 ASW Crevice SAW Aqueous Phase 60C 56.3118 0.0018 46,296 56.912 6.89 
DCB049 2.0045 2.0070 0.0865 46.3703 ASW Crevice SAW Vapor Phase 90C 46.3662 0.0041 45,960 55.948 16.08 
DCB050 2.0050 2.0115 0.0840 44.8726 ASW Crevice SAW Vapor Phase 90C 44.8689 0.0037 45,960 55.938 14.52 
DCB052 2.0040 2.0040 0.0925 50.3147 ASW Crevice SAW Aqueous Phase 90C 50.3136 0.0011 45,960 56.202 4.30 
DCB053 2.0000 2.0065 0.0830 45.6403 ASW Crevice SAW Aqueous Phase 90C 45.6388 0.0015 45,960 55.610 5.92 
DCB079 2.0010 2.0030 0.0835 45.7966 ASW Crevice SCW Vapor Phase 60C 45.7961 0.0005 45,456 55.572 2.00 
DCB080 2.0130 2.0000 0.0920 52.2193 ASW Crevice SCW Vapor Phase 60C 52.2173 0.0020 45,456 56.307 7.88 
DCB082 2.0010 1.9990 0.0840 46.2660 ASW Crevice SCW Aqueous Phase 60C 46.2611 0.0049 45,456 55.493 19.59 
DCB083 1.9970 1.9965 0.0855 48.1762 ASW Crevice SCW Aqueous Phase 60C 48.1728 0.0034 45,456 55.405 13.62 
DCB109 2.0060 2.0150 0.1040 57.7242 ASW Crevice SCW Vapor Phase 90C 57.7231 0.0011 44,832 57.223 4.33 
DCB110 1.9940 1.9990 0.0950 51.1169 ASW Crevice SCW Vapor Phase 90C 51.1164 0.0005 44,832 55.941 2.02 
DCB112 2.0105 2.0095 0.1035 56.9739 ASW Crevice SCW Aqueous Phase 90C 56.9716 0.0023 44,832 57.167 9.05 
DCB113 2.0055 2.0040 0.0870 48.0842 ASW Crevice SCW Aqueous Phase 90C 48.0815 0.0027 44,832 55.923 10.86 
DCB139 1.9805 1.9860 0.1045 56.1890 ASW Crevice SDW Vapor Phase 60C 56.1890 0.0000 44,448 55.775 0.01 
DCB140 1.9965 1.9975 0.0920 48.7987 ASW Crevice SDW Vapor Phase 60C 48.7980 0.0007 44,448 55.795 2.85 
DCB142 2.0015 2.0025 0.0900 49.2450 ASW Crevice SDW Aqueous Phase 60C 49.2445 0.0005 44,448 55.949 2.03 
DCB143 1.9985 1.9985 0.0900 49.7742 ASW Crevice SDW Aqueous Phase 60C 49.7728 0.0014 44,448 55.760 5.70 
DCB175 1.9990 2.0060 0.1090 59.1477 ASW Crevice SDW Vapor Phase 90C 59.1476 0.0001 43,488 57.077 0.41 
DCB176 2.0050 2.0030 0.0825 45.3890 ASW Crevice SDW Vapor Phase 90C 45.3885 0.0005 43,488 55.621 2.09 
DCB178 2.0015 2.0035 0.0865 47.7164 ASW Crevice SDW Aqueous Phase 90C 47.7161 0.0003 43,488 55.773 1.26 
DCB179 2.0040 2.0120 0.0845 47.0565 ASW Crevice SDW Aqueous Phase 90C 47.0564 0.0001 43,488 55.953 0.42 
Source DTN: LL030412512251.057 [DIRS 163712] 
NOTES: a MA = mill annealed, ASW = as-welded. 
b Outlier not included in the analysis 
c The input data from DTN: LL030412512251.057 [DIRS 163712] are the initial and final weight measurements, sample dimensions, and exposure 
conditions and time. The sample surface areas and corrosion rates were calculated in this report. The calculated corrosion rates in this table are 
slightly different from those in DTN: LL030412512251.057 [DIRS 163712] due to differences in the number of significant digits used. The final weight is 
the mean of the three weight measurements taken after the final cleaning to remove observable surface deposits. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 III-1 October 2004 
APPENDIX III 
GENERAL CORROSION RATE OF ALLOY 22 WEIGHT-LOSS SAMPLES BASED ON 
THE WEIGHT-LOSS MEASUREMENT AFTER 5-YEAR EXPOSURE IN THE LONGTERM 
CORROSION TEST FACILITY. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 III-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 III-3 October 2004 
III. GENERAL CORROSION RATE OF ALLOY 22 WEIGHT-LOSS SAMPLES BASED ON THE WEIGHT-LOSS 
MEASUREMENT AFTER 5-YEAR EXPOSURE IN THE LONG-TERM CORROSION TEST FACILITY 
Sample ID 
Length 
(in.) 
Width 
(in.) 
Thickness 
(in.) 
Initial 
Weight 
(g) 
Sample 
Condition a) Exposure Environment 
Final 
Weight (g) 
Weight 
Loss (g) 
Exposed 
Time (hours) 
Surface Area 
(cm2) 
Corrosion 
Rate 
(nm/yr) d) 
DWA019 2.0135 1.0100 0.1120 30.3252 MA WL SAW Vapor Phase 60C 30.3246 0.0006 46,296 30.3317 4.32 
DWA020 2.0135 1.0085 0.1130 30.9953 MA WL SAW Vapor Phase 60C 30.9950 0.0003 46,296 30.3359 2.17 
DWA021 2.0145 1.0095 0.1140 31.0549 MA WL SAW Vapor Phase 60C 31.0544 0.0005 46,296 30.4231 3.59 
DWA022 2.0120 1.0115 0.1140 31.0362 MA WL SAW Aqueous Phase 60C 31.0361 0.0001 46,296 30.4417 0.73 
DWA023 2.0110 1.0095 0.1125 30.2366 MA WL SAW Aqueous Phase 60C 30.2361 0.0005 46,296 30.3044 3.61 
DWA024 2.0095 1.0085 0.0945 25.6040 MA WL SAW Aqueous Phase 60C 25.6035 0.0005 46,296 29.4406 3.71 
DWA034 2.0145 1.0105 0.1125 30.5218 MA WL SAW Waterline 60C c) 30.5213 0.0005 46,296 30.3826 3.60 
DWA039 2.0155 1.0120 0.1145 31.2482 MA WL SAW Waterline 90C c) 31.2476 0.0006 45,960 30.5290 4.33 
DWA059 2.0100 1.0110 0.1130 30.5308 MA WL SAW Vapor Phase 90C 30.5304 0.0004 45,960 30.3537 2.90 
DWA060 2.0135 1.0095 0.1130 30.9395 MA WL SAW Vapor Phase 90C 30.9391 0.0004 45,960 30.3633 2.90 
DWA061 2.0170 1.0120 0.1105 29.9892 MA WL SAW Vapor Phase 90C 29.9891 0.0001 45,960 30.3692 0.74 
DWA062 2.0120 1.0090 0.1120 30.0884 MA WL SAW Aqueous Phase 90C 30.0882 0.0002 45,960 30.2826 1.46 
DWA063 2.0145 1.0100 0.1145 31.0229 MA WL SAW Aqueous Phase 90C 31.0225 0.0004 45,960 30.4595 2.89 
DWA064 2.0080 1.0100 0.1150 30.5525 MA WL SAW Aqueous Phase 90C 30.5521 0.0004 45,960 30.3879 2.90 
DWA089 b) 2.0145 1.0120 0.1160 31.0278 MA WL SCW Vapor Phase 60C 31.0280 -0.0002 45,456 30.5825 -1.44 
DWA090 2.0175 1.0105 0.1145 30.7848 MA WL SCW Vapor Phase 60C 30.7848 0.0000 45,456 30.5168 0.01 
DWA091 2.0150 1.0070 0.1160 30.8690 MA WL SCW Vapor Phase 60C 30.8687 0.0003 45,456 30.4523 2.20 
DWA092 2.0100 1.0095 0.1065 29.9109 MA WL SCW Aqueous Phase 60C 29.9106 0.0003 45,456 30.0183 2.23 
DWA093 2.0090 1.0095 0.1100 29.7822 MA WL SCW Aqueous Phase 60C 29.7820 0.0002 45,456 30.1623 1.49 
DWA094 2.0155 1.0115 0.1165 30.8081 MA WL SCW Aqueous Phase 60C 30.8077 0.0004 45,456 30.6060 2.91 
DWA104 2.0140 1.0100 0.1120 30.6273 MA WL SCW Waterline 60C c) 30.6270 0.0003 45,456 30.3389 2.21 
DWA109 2.0160 1.0110 0.1100 30.0620 MA WL SCW Waterline 90C c) 30.0620 0.0000 45,984 30.3046 0.01 
DWA129 2.0155 1.0090 0.1005 27.1346 MA WL SCW Vapor Phase 90C 27.1343 0.0003 44,832 29.8117 2.28 
DWA130 2.0105 1.0125 0.1160 31.3506 MA WL SCW Vapor Phase 90C 31.3501 0.0005 44,832 30.5380 3.70 
DWA131 2.0190 1.0115 0.1130 30.7217 MA WL SCW Vapor Phase 90C 30.7215 0.0002 44,832 30.4980 1.49 
DWA132 2.0135 1.0095 0.1090 29.0636 MA WL SCW Aqueous Phase 90C 29.0623 0.0013 44,832 30.1820 9.70 
DWA133 2.0160 1.0100 0.1115 30.2796 MA WL SCW Aqueous Phase 90C 30.2786 0.0010 44,832 30.3452 7.42 
DWA134 2.0155 1.0100 0.1150 30.8393 MA WL SCW Aqueous Phase 90C 30.8385 0.0008 44,832 30.4967 5.91 
DWA147 2.0135 1.0090 0.1155 31.2833 MA WL SDW Vapor Phase 60C 31.2833 0.0000 44,448 30.4629 0.01 
DWA148 2.0130 1.0100 0.1050 28.2562 MA WL SDW Aqueous Phase 60C 28.2561 0.0001 44,448 30.0071 0.77 
DWA154 2.0185 1.0100 0.1140 30.7483 MA WL SDW Waterline 60C c) 30.7479 0.0004 44,448 30.4949 2.99 
DWA167 2.0010 1.0030 0.1255 33.5921 MA WL SDW Waterline 90C c) 33.5918 0.0003 43,488 30.5685 2.29 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 III-4 October 2004 
Sample ID 
Length 
(in.) 
Width 
(in.) 
Thickness 
(in.) 
Initial 
Weight 
(g) 
Sample 
Condition a) Exposure Environment 
Final 
Weight (g) 
Weight 
Loss (g) 
Exposed 
Time (hours) 
Surface Area 
(cm2) 
Corrosion 
Rate 
(nm/yr) d) 
DWA174 2.0015 1.0025 0.1250 33.6543 MA WL SDW Vapor Phase 90C 33.6542 0.0001 43,488 30.5395 0.77 
DWA175 2.0020 0.9960 0.1245 33.2710 MA WL SDW Aqueous Phase 90C 33.2710 0.0000 43,488 30.3459 0.02 
DWB019 2.0000 1.0055 0.1005 27.1924 ASW WL SAW Vapor Phase 60C 27.1922 0.0002 46,296 29.4949 1.49 
DWB020 1.9990 1.0030 0.1000 27.0152 ASW WL SAW Vapor Phase 60C 27.0152 0.0000 46,296 29.3904 0.01 
DWB021 1.9995 1.0050 0.1000 27.2070 ASW WL SAW Vapor Phase 60C 27.2070 0.0000 46,296 29.4517 0.01 
DWB022 1.9995 1.0035 0.0980 26.6246 ASW WL SAW Aqueous Phase 60C 26.6241 0.0005 46,296 29.3209 3.73 
DWB023 2.0045 1.0070 0.0940 25.5992 ASW WL SAW Aqueous Phase 60C 25.5990 0.0002 46,296 29.3062 1.50 
DWB024 1.9920 1.0010 0.1045 28.0650 ASW WL SAW Aqueous Phase 60C 28.0645 0.0005 46,296 29.4390 3.71 
DWB059 1.9990 1.0060 0.1095 29.6327 ASW WL SAW Vapor Phase 90C 29.6327 0.0000 45,960 29.9001 0.01 
DWB060 2.0020 1.0065 0.1120 30.1549 ASW WL SAW Vapor Phase 90C 30.1548 0.0001 45,960 30.0697 0.74 
DWB061 1.9960 1.0065 0.1075 28.9565 ASW WL SAW Vapor Phase 90C 28.9563 0.0002 45,960 29.7803 1.49 
DWB062 2.0000 1.0050 0.1080 29.1079 ASW WL SAW Aqueous Phase 90C 29.1073 0.0006 45,960 29.8196 4.43 
DWB063 1.9985 1.0050 0.1075 29.0647 ASW WL SAW Aqueous Phase 90C 29.0646 0.0001 45,960 29.7755 0.75 
DWB064 1.9955 1.0025 0.1105 29.2528 ASW WL SAW Aqueous Phase 90C 29.2526 0.0002 45,960 29.7996 1.49 
DWB089 2.0000 1.0045 0.1130 30.0101 ASW WL SCW Vapor Phase 60C 30.0100 0.0001 45,456 30.0314 0.75 
DWB090 2.0015 1.0045 0.0995 27.0584 ASW WL SCW Vapor Phase 60C 27.0583 0.0001 45,456 29.4441 0.77 
DWB091 1.9950 1.0020 0.0980 26.6267 ASW WL SCW Vapor Phase 60C 26.6267 0.0000 45,456 29.2164 0.02 
DWB092 1.9970 1.0005 0.0960 26.1388 ASW WL SCW Aqueous Phase 60C 26.1385 0.0003 45,456 29.1143 2.30 
DWB093 1.9950 1.0050 0.1090 29.3467 ASW WL SCW Aqueous Phase 60C 29.3462 0.0005 45,456 29.7928 3.74 
DWB094 1.9910 0.9995 0.1075 28.8795 ASW WL SCW Aqueous Phase 60C 28.8786 0.0009 45,456 29.5189 6.78 
DWB129 1.9780 1.0055 0.1075 29.1972 ASW WL SCW Vapor Phase 90C 29.1971 0.0001 44,832 29.4947 0.78 
DWB130 1.9955 1.0020 0.1065 28.6787 ASW WL SCW Vapor Phase 90C 28.6784 0.0003 44,832 29.6060 2.29 
DWB131 2.0040 1.0050 0.1070 29.2996 ASW WL SCW Vapor Phase 90C 29.2993 0.0003 44,832 29.8319 2.28 
DWB132 2.0000 1.0025 0.1065 28.7651 ASW WL SCW Aqueous Phase 90C 28.7637 0.0014 44,832 29.6840 10.62 
DWB133 2.0000 1.0015 0.1105 29.7020 ASW WL SCW Aqueous Phase 90C 29.7005 0.0015 44,832 29.8370 11.32 
DWB134 1.9960 1.0040 0.1075 29.2460 ASW WL SCW Aqueous Phase 90C 29.2444 0.0016 44,832 29.7125 12.12 
DWB147 1.9955 1.0025 0.1060 28.6604 ASW WL SDW Vapor Phase 60C 28.6603 0.0001 44,448 29.5971 0.78 
DWB148 1.9955 1.0045 0.1085 29.4282 ASW WL SDW Aqueous Phase 60C 29.4280 0.0002 44,448 29.7639 1.54 
DWB 174 1.9960 0.9960 0.1180 30.5213 ASW WL SDW Vapor Phase 90C 30.5210 0.0003 43,488 29.9671 2.34 
DWB175 2.0000 0.9995 0.1110 28.4575 ASW WL SDW Aqueous Phase 90C 28.4573 0.0002 43,488 29.8051 1.57 
Source: DTN: LL030412512251.057 [DIRS 163712]. 
NOTE: a MA = mill annealed, ASW = as-welded, WL = weight loss. 
b Negative rate conservatively not included in the analysis. 
c The waterline data are treated as the aqueous phase data in the analysis. 
d The input data from DTN: LL030412512251.057 [DIRS 163712] are the initial and final weight measurements, sample dimensions, and exposure 
conditions and time. The sample surface areas and corrosion rates were calculated in this report. The calculated corrosion rates in this table are slightly 
different from those in DTN: LL030412512251.057 [DIRS 163712] due to differences in the number of significant digits used. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-1 October 2004 
APPENDIX IV 
CORROSION RATE OF ALLOY 22 AS A FUNCTION OF TEMPERATURE 
CALCULATED FROM POLARIZATION RESISTANCE MEASUREMENTS 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-3 October 2004 
IV. CORROSION RATE OF ALLOY 22 AS A FUNCTION OF TEMPERATURE CALCULATED FROM 
POLARIZATION RESISTANCE MEASUREMENTS 
Note: The corrosion rates from the polarization resistance measurements in this table are for comparative analysis of the temperature 
dependence of the corrosion rate. The measurements are not intended for obtaining the absolute values of the corrosion rate. 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030309512251.042 [DIRS 163455] DEA3264 MCA MA 1M NaCl 60 0.00300 7.50 266 
LL030309512251.042 [DIRS 163455] DEA3264 MCA MA 1M NaCl 60 0.00300 7.50 335 
LL030309512251.042 [DIRS 163455] DEA3264 MCA MA 1M NaCl 60 0.00300 7.50 313 
LL030309512251.042 [DIRS 163455] DEA3265 MCA MA 1M NaCl 60 0.00300 7.68 1,553 
LL030309512251.042 [DIRS 163455] DEA3265 MCA MA 1M NaCl 60 0.00300 7.68 1,166 
LL030309512251.042 [DIRS 163455] DEA3265 MCA MA 1M NaCl 60 0.00300 7.68 1,265 
LL030309512251.042 [DIRS 163455] DEA3262 MCA MA 1M NaCl 90 0.00275 7.63 1,927 
LL030309512251.042 [DIRS 163455] DEA3262 MCA MA 1M NaCl 90 0.00275 7.63 1,660 
LL030309512251.042 [DIRS 163455] DEA3262 MCA MA 1M NaCl 90 0.00275 7.63 1,361 
LL030309512251.042 [DIRS 163455] DEA3263 MCA MA 1M NaCl 90 0.00275 7.68 2,554 
LL030309512251.042 [DIRS 163455] DEA3263 MCA MA 1M NaCl 90 0.00275 7.68 2,401 
LL030309512251.042 [DIRS 163455] DEA3263 MCA MA 1M NaCl 90 0.00275 7.68 1,286 
LL030309512251.042 [DIRS 163455] DEA3147 MCA MA 1.25M NaCl 60 0.00300 6.99 774 
LL030309512251.042 [DIRS 163455] DEA3147 MCA MA 1.25M NaCl 60 0.00300 6.99 700 
LL030309512251.042 [DIRS 163455] DEA3147 MCA MA 1.25M NaCl 60 0.00300 6.99 580 
LL030309512251.042 [DIRS 163455] DEA3148 MCA MA 1.25M NaCl 60 0.00300 6.49 754 
LL030309512251.042 [DIRS 163455] DEA3148 MCA MA 1.25M NaCl 60 0.00300 6.49 866 
LL030309512251.042 [DIRS 163455] DEA3148 MCA MA 1.25M NaCl 60 0.00300 6.49 835 
LL030309512251.042 [DIRS 163455] DEA3267 MCA MA 1.25M NaCl 60 0.00300 7.95 139 
LL030309512251.042 [DIRS 163455] DEA3267 MCA MA 1.25M NaCl 60 0.00300 7.95 146 
LL030309512251.042 [DIRS 163455] DEA3267 MCA MA 1.25M NaCl 60 0.00300 7.95 166 
LL030309512251.042 [DIRS 163455] DEA3268 MCA MA 1.25M NaCl 60 0.00300 7.61 525 
LL030309512251.042 [DIRS 163455] DEA3268 MCA MA 1.25M NaCl 60 0.00300 7.61 584 
LL030309512251.042 [DIRS 163455] DEA3268 MCA MA 1.25M NaCl 60 0.00300 7.61 669 
LL030309512251.042 [DIRS 163455] DEA3273 MCA MA 1.25M NaCl 60 0.00300 7.06 133 
LL030309512251.042 [DIRS 163455] DEA3273 MCA MA 1.25M NaCl 60 0.00300 7.06 51 
LL030309512251.042 [DIRS 163455] DEA3273 MCA MA 1.25M NaCl 60 0.00300 7.06 151 
LL030309512251.042 [DIRS 163455] DEA3269 MCA MA 1.25M NaCl 90 0.00275 7.09 1,205 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-4 October 2004 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030309512251.042 [DIRS 163455] DEA3269 MCA MA 1.25M NaCl 90 0.00275 7.09 1,036 
LL030309512251.042 [DIRS 163455] DEA3269 MCA MA 1.25M NaCl 90 0.00275 7.09 612 
LL030309512251.042 [DIRS 163455] DEA3271 MCA MA 1.25M NaCl 90 0.00275 7.32 407 
LL030309512251.042 [DIRS 163455] DEA3271 MCA MA 1.25M NaCl 90 0.00275 7.32 509 
LL030309512251.042 [DIRS 163455] DEA3271 MCA MA 1.25M NaCl 90 0.00275 7.32 226 
LL030309512251.042 [DIRS 163455] DEA3182 MCA MA 1.25M CaCl2 60 0.00300 6.78 164 
LL030309512251.042 [DIRS 163455] DEA3182 MCA MA 1.25M CaCl2 60 0.00300 6.78 260 
LL030309512251.042 [DIRS 163455] DEA3182 MCA MA 1.25M CaCl2 60 0.00300 6.78 231 
LL030309512251.042 [DIRS 163455] DEA3183 MCA MA 1.25M CaCl2 60 0.00300 6.77 198 
LL030309512251.042 [DIRS 163455] DEA3183 MCA MA 1.25M CaCl2 60 0.00300 6.77 92 
LL030309512251.042 [DIRS 163455] DEA3184 MCA MA 1.25M CaCl2 90 0.00275 6.78 2,323 
LL030309512251.042 [DIRS 163455] DEA3184 MCA MA 1.25M CaCl2 90 0.00275 6.78 1,698 
LL030309512251.042 [DIRS 163455] DEA3184 MCA MA 1.25M CaCl2 90 0.00275 6.78 1,778 
LL030309512251.042 [DIRS 163455] DEA3185 MCA MA 1.25M CaCl2 90 0.00275 7.39 3,553 
LL030309512251.042 [DIRS 163455] DEA3185 MCA MA 1.25M CaCl2 90 0.00275 7.39 2,420 
LL030309512251.042 [DIRS 163455] DEA3185 MCA MA 1.25M CaCl2 90 0.00275 7.39 3,095 
LL030309512251.042 [DIRS 163455] DEA3274 MCA MA 2.5M CaCl2 60 0.00300 7.05 255 
LL030309512251.042 [DIRS 163455] DEA3274 MCA MA 2.5M CaCl2 60 0.00300 7.05 1,162 
LL030309512251.042 [DIRS 163455] DEA3274 MCA MA 2.5M CaCl2 60 0.00300 7.05 946 
LL030309512251.042 [DIRS 163455] DEA3275 MCA MA 2.5M CaCl2 60 0.00300 7.04 1,212 
LL030309512251.042 [DIRS 163455] DEA3275 MCA MA 2.5M CaCl2 60 0.00300 7.04 304 
LL030309512251.042 [DIRS 163455] DEA3275 MCA MA 2.5M CaCl2 60 0.00300 7.04 327 
LL030309512251.042 [DIRS 163455] DEA3189 MCA MA 2.5M CaCl2 90 0.00275 6.32 6,866 
LL030309512251.042 [DIRS 163455] DEA3189 MCA MA 2.5M CaCl2 90 0.00275 6.32 6,627 
LL030309512251.042 [DIRS 163455] DEA3189 MCA MA 2.5M CaCl2 90 0.00275 6.32 6,529 
LL030309512251.042 [DIRS 163455] DEA3190 MCA MA 2.5M CaCl2 90 0.00275 6.98 5,232 
LL030309512251.042 [DIRS 163455] DEA3190 MCA MA 2.5M CaCl2 90 0.00275 6.98 5,559 
LL030309512251.042 [DIRS 163455] DEA3190 MCA MA 2.5M CaCl2 90 0.00275 6.98 5,861 
LL030309512251.042 [DIRS 163455] DEA3186 MCA MA 5M CaCl2 45 0.00314 5.42 1,703 
LL030309512251.042 [DIRS 163455] DEA3186 MCA MA 5M CaCl2 45 0.00314 5.42 1,684 
LL030309512251.042 [DIRS 163455] DEA3186 MCA MA 5M CaCl2 45 0.00314 5.42 1,749 
LL030309512251.042 [DIRS 163455] DEA3187 MCA MA 5M CaCl2 45 0.00314 5.53 1,756 
LL030309512251.042 [DIRS 163455] DEA3187 MCA MA 5M CaCl2 45 0.00314 5.53 1,539 
LL030309512251.042 [DIRS 163455] DEA3187 MCA MA 5M CaCl2 45 0.00314 5.53 1,573 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-5 October 2004 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030309512251.042 [DIRS 163455] DEA3180 MCA MA 5M CaCl2 60 0.00300 6.06 3,554 
LL030309512251.042 [DIRS 163455] DEA3180 MCA MA 5M CaCl2 60 0.00300 6.06 3,017 
LL030309512251.042 [DIRS 163455] DEA3180 MCA MA 5M CaCl2 60 0.00300 6.06 2,998 
LL030309512251.042 [DIRS 163455] DEA3181 MCA MA 5M CaCl2 60 0.00300 5.95 2,294 
LL030309512251.042 [DIRS 163455] DEA3181 MCA MA 5M CaCl2 60 0.00300 5.95 2,698 
LL030309512251.042 [DIRS 163455] DEA3181 MCA MA 5M CaCl2 60 0.00300 5.95 2,542 
LL030309512251.042 [DIRS 163455] DEA3260 MCA MA 5M CaCl2 75 0.00287 5.73 5,334 
LL030309512251.042 [DIRS 163455] DEA3260 MCA MA 5M CaCl2 75 0.00287 5.73 5,366 
LL030309512251.042 [DIRS 163455] DEA3260 MCA MA 5M CaCl2 75 0.00287 5.73 5,174 
LL030309512251.042 [DIRS 163455] DEA3261 MCA MA 5M CaCl2 75 0.00287 6.07 3,678 
LL030309512251.042 [DIRS 163455] DEA3261 MCA MA 5M CaCl2 75 0.00287 6.07 3,386 
LL030309512251.042 [DIRS 163455] DEA3261 MCA MA 5M CaCl2 75 0.00287 6.07 3,323 
LL030309512251.042 [DIRS 163455] DEA3176 MCA MA 5M CaCl2 90 0.00275 5.58 4,947 
LL030309512251.042 [DIRS 163455] DEA3176 MCA MA 5M CaCl2 90 0.00275 5.58 4,798 
LL030309512251.042 [DIRS 163455] DEA3176 MCA MA 5M CaCl2 90 0.00275 5.58 4,344 
LL030309512251.042 [DIRS 163455] DEA3177 MCA MA 5M CaCl2 90 0.00275 5.74 6,487 
LL030309512251.042 [DIRS 163455] DEA3177 MCA MA 5M CaCl2 90 0.00275 5.74 5,863 
LL030309512251.042 [DIRS 163455] DEA3177 MCA MA 5M CaCl2 90 0.00275 5.74 5,398 
LL030309512251.042 [DIRS 163455] DEA3167 MCA MA 5M CaCl2 105 0.00264 6.14 19,210 
LL030309512251.042 [DIRS 163455] DEA3167 MCA MA 5M CaCl2 105 0.00264 6.14 18,240 
LL030309512251.042 [DIRS 163455] DEA3167 MCA MA 5M CaCl2 105 0.00264 6.14 17,450 
LL030309512251.042 [DIRS 163455] DEA3168 MCA MA 5M CaCl2 105 0.00264 6.12 6,101 
LL030309512251.042 [DIRS 163455] DEA3168 MCA MA 5M CaCl2 105 0.00264 6.12 5,850 
LL030309512251.042 [DIRS 163455] DEA3168 MCA MA 5M CaCl2 105 0.00264 6.12 5,428 
LL030409812251.054 [DIRS 164185] DEA3125 MCA MA 7M CaCl2 130 0.00248 4.14 7,505 
LL030409812251.054 [DIRS 164185] DEA3125 MCA MA 7M CaCl2 130 0.00248 4.14 5,711 
LL030409812251.054 [DIRS 164185] DEA3125 MCA MA 7M CaCl2 130 0.00248 4.14 6,572 
LL030409812251.054 [DIRS 164185] DEA599 Disc MA 7M CaCl2 130 0.00248 4.14 6,803 
LL030409812251.054 [DIRS 164185] DEA599 Disc MA 7M CaCl2 130 0.00248 4.14 6,344 
LL030409812251.054 [DIRS 164185] DEA599 Disc MA 7M CaCl2 130 0.00248 4.14 6,551 
LL030409812251.054 [DIRS 164185] DEA595 Disc MA 8M CaCl2 100 0.00268 4.14 2,212 
LL030409812251.054 [DIRS 164185] DEA595 Disc MA 8M CaCl2 100 0.00268 4.14 2,118 
LL030409812251.054 [DIRS 164185] DEA595 Disc MA 8M CaCl2 100 0.00268 4.14 1,763 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-6 October 2004 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030409812251.054 [DIRS 164185] DEA595 Disc MA 8M CaCl2 100 0.00268 4.14 2,005 
LL030409812251.054 [DIRS 164185] DEA596 Disc MA 9M CaCl2 150 0.00236 4.14 20,270 
LL030409812251.054 [DIRS 164185] DEA596 Disc MA 9M CaCl2 150 0.00236 4.14 18,820 
LL030409812251.054 [DIRS 164185] DEA596 Disc MA 9M CaCl2 150 0.00236 4.14 18,760 
LL030409812251.054 [DIRS 164185] DEA3105 MCA MA 1.25M CaCl2 + 0.0125M 
Ca(NO3)2 60 0.00300 6.81 1,618 
LL030409812251.054 [DIRS 164185] DEA3105 MCA MA 1.25M CaCl2 + 0.0125M 
Ca(NO3)2 60 0.00300 6.81 1,990 
LL030409812251.054 [DIRS 164185] DEA3105 MCA MA 1.25M CaCl2 + 0.0125M 
Ca(NO3)2 60 0.00300 6.81 981 
LL030409812251.054 [DIRS 164185] DEA3108 MCA MA 1.25M CaCl2 + 0.125M 
Ca(NO3)2 60 0.00300 7.02 211 
LL030409812251.054 [DIRS 164185] DEA3108 MCA MA 1.25M CaCl2 + 0.125M 
Ca(NO3)2 60 0.00300 7.02 154 
LL030409812251.054 [DIRS 164185] DEA3108 MCA MA 1.25M CaCl2 + 0.125M 
Ca(NO3)2 60 0.00300 7.02 160 
LL030409812251.054 [DIRS 164185] DEA3109 MCA MA 1.25M CaCl2 + 0.125M 
Ca(NO3)2 90 0.00275 6.47 654 
LL030409812251.054 [DIRS 164185] DEA3109 MCA MA 1.25M CaCl2 + 0.125M 
Ca(NO3)2 90 0.00275 6.47 1,821 
LL030409812251.054 [DIRS 164185] DEA3109 MCA MA 1.25M CaCl2 + 0.125M 
Ca(NO3)2 90 0.00275 6.47 1,333 
LL030409812251.054 [DIRS 164185] DEA3101 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 60 0.00300 4.64 1,043 
LL030409812251.054 [DIRS 164185] DEA3101 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 60 0.00300 4.64 994 
LL030409812251.054 [DIRS 164185] DEA3101 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 60 0.00300 4.64 912 
LL030409812251.054 [DIRS 164185] DEA3103 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 60 0.00300 5.02 1,193 
LL030409812251.054 [DIRS 164185] DEA3103 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 60 0.00300 5.02 916 
LL030409812251.054 [DIRS 164185] DEA3103 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 60 0.00300 5.02 1,130 
LL030409812251.054 [DIRS 164185] DEA3102 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.13 1,418 
LL030409812251.054 [DIRS 164185] DEA3102 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.13 1,196 
LL030409812251.054 [DIRS 164185] DEA3104 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.37 1,739 
LL030409812251.054 [DIRS 164185] DEA3104 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.37 2,215 
LL030409812251.054 [DIRS 164185] DEA3104 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.37 2,221 
LL030409812251.054 [DIRS 164185] DEA3123 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 105 0.00264 5.74 3,052 
LL030409812251.054 [DIRS 164185] DEA3123 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 105 0.00264 5.74 2,906 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-7 October 2004 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030409812251.054 [DIRS 164185] DEA3123 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 105 0.00264 5.74 2,810 
LL030409812251.054 [DIRS 164185] DEA3124 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 105 0.00264 5.76 4,488 
LL030409812251.054 [DIRS 164185] DEA3124 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 105 0.00264 5.76 3,971 
LL030409812251.054 [DIRS 164185] DEA3124 MCA MA 5M CaCl2 + 0.5M Ca(NO3)2 105 0.00264 5.76 3,887 
LL030409812251.054 [DIRS 164185] DEA598 Disc MA 6M CaCl2 + 0.6M Ca(NO3)2 120 0.00254 5.34 2,647 
LL030409812251.054 [DIRS 164185] DEA598 Disc MA 6M CaCl2 + 0.6M Ca(NO3)2 120 0.00254 5.34 2,244 
LL030409812251.054 [DIRS 164185] DEA598 Disc MA 6M CaCl2 + 0.6M Ca(NO3)2 120 0.00254 5.34 2,523 
LL030409812251.054 [DIRS 164185] DEA3127 MCA MA 7M CaCl2 + 0.7M Ca(NO3)2 130 0.00248 5.34 3,117 
LL030409812251.054 [DIRS 164185] DEA3127 MCA MA 7M CaCl2 + 0.7M Ca(NO3)2 130 0.00248 5.34 2,445 
LL030409812251.054 [DIRS 164185] DEA3127 MCA MA 7M CaCl2 + 0.7M Ca(NO3)2 130 0.00248 5.34 2,638 
LL030409812251.054 [DIRS 164185] DEA600 Disc MA 7M CaCl2 + 0.7M Ca(NO3)2 130 0.00248 5.34 1,946 
LL030409812251.054 [DIRS 164185] DEA600 Disc MA 7M CaCl2 + 0.7M Ca(NO3)2 130 0.00248 5.34 1,304 
LL030409812251.054 [DIRS 164185] DEA600 Disc MA 7M CaCl2 + 0.7M Ca(NO3)2 130 0.00248 5.34 1,812 
LL030409812251.054 [DIRS 164185] DEA3118 MCA MA 8M CaCl2 + 0.8M Ca(NO3)2 140 0.00242 5.34 1,775 
LL030409812251.054 [DIRS 164185] DEA3118 MCA MA 8M CaCl2 + 0.8M Ca(NO3)2 140 0.00242 5.34 3,659 
LL030409812251.054 [DIRS 164185] DEA3118 MCA MA 8M CaCl2 + 0.8M Ca(NO3)2 140 0.00242 5.34 6,509 
LL030409812251.054 [DIRS 164185] DEA3119 MCA MA 8M CaCl2 + 0.8M Ca(NO3)2 140 0.00242 5.34 1,147 
LL030409812251.054 [DIRS 164185] DEA3119 MCA MA 8M CaCl2 + 0.8M Ca(NO3)2 140 0.00242 5.34 1,202 
LL030409812251.054 [DIRS 164185] DEA3119 MCA MA 8M CaCl2 + 0.8M Ca(NO3)2 140 0.00242 5.34 896 
LL030409812251.054 [DIRS 164185] DEA597 Disc MA 9M CaCl2 + 0.9M Ca(NO3)2 150 0.00236 5.34 5,602 
LL030409812251.054 [DIRS 164185] DEA597 Disc MA 9M CaCl2 + 0.9M Ca(NO3)2 150 0.00236 5.34 4,817 
LL030409812251.054 [DIRS 164185] DEA597 Disc MA 9M CaCl2 + 0.9M Ca(NO3)2 150 0.00236 5.34 5,139 
LL030409812251.054 [DIRS 164185] DEA3120 MCA MA 9M CaCl2 + 0.9M Ca(NO3)2 160 0.00231 5.34 5,041 
LL030409812251.054 [DIRS 164185] DEA3120 MCA MA 9M CaCl2 + 0.9M Ca(NO3)2 160 0.00231 5.34 4,710 
LL030409812251.054 [DIRS 164185] DEA3120 MCA MA 9M CaCl2 + 0.9M Ca(NO3)2 160 0.00231 5.34 6,839 
LL030409812251.054 [DIRS 164185] DEA3122 MCA MA 9M CaCl2 + 0.9M Ca(NO3)2 170 0.00226 5.34 2,692 
LL030409812251.054 [DIRS 164185] DEA3122 MCA MA 9M CaCl2 + 0.9M Ca(NO3)2 170 0.00226 5.34 7,070 
LL030409812251.054 [DIRS 164185] DEA3122 MCA MA 9M CaCl2 + 0.9M Ca(NO3)2 170 0.00226 5.34 2,729 
LL030309512251.042 [DIRS 163455] KK006 Prism ASW 1M NaCl 90 0.00275 6.70 157 
LL030309512251.042 [DIRS 163455] KK006 Prism ASW 1M NaCl 90 0.00275 6.70 211 
LL030502212251.063 [DIRS 163456] JE 0022 MCA ASW 5M CaCl2 115.5 0.00257 5.95 3,613 
LL030502212251.063 [DIRS 163456] JE 0022 MCA ASW 5M CaCl2 115.5 0.00257 5.95 5,848 
LL030502212251.063 [DIRS 163456] JE 0022 MCA ASW 5M CaCl2 115.5 0.00257 5.95 4,770 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-8 October 2004 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030502212251.063 [DIRS 163456] JE 0023 MCA ASW 5M CaCl2 116.4 0.00257 5.96 10,470 
LL030502212251.063 [DIRS 163456] JE 0023 MCA ASW 5M CaCl2 116.4 0.00257 5.96 11,040 
LL030502212251.063 [DIRS 163456] JE 0023 MCA ASW 5M CaCl2 116.4 0.00257 5.96 12,770 
LL030502212251.063 [DIRS 163456] JE 0032 MCA ASW 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.73 1,649 
LL030502212251.063 [DIRS 163456] JE 0032 MCA ASW 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.73 1,590 
LL030502212251.063 [DIRS 163456] JE 0032 MCA ASW 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.73 972 
LL030502212251.063 [DIRS 163456] JE 0033 MCA ASW 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.85 1,696 
LL030502212251.063 [DIRS 163456] JE 0033 MCA ASW 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.85 2,347 
LL030502212251.063 [DIRS 163456] JE 0033 MCA ASW 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.85 1,047 
LL030502212251.063 [DIRS 163456] JE 0024 MCA ASW 5M CaCl2+0.05M Ca(NO3)2 118.4 0.00255 5.89 9,428 
LL030502212251.063 [DIRS 163456] JE 0024 MCA ASW 5M CaCl2+0.05M Ca(NO3)2 118.4 0.00255 5.89 9,360 
LL030502212251.063 [DIRS 163456] JE 0024 MCA ASW 5M CaCl2+0.05M Ca(NO3)2 118.4 0.00255 5.89 8,894 
LL030502212251.063 [DIRS 163456] JE 0025 MCA ASW 5M CaCl2+0.05M Ca(NO3)2 118.6 0.00255 5.94 8,081 
LL030502212251.063 [DIRS 163456] JE 0025 MCA ASW 5M CaCl2+0.05M Ca(NO3)2 118.6 0.00255 5.94 7,893 
LL030502212251.063 [DIRS 163456] JE 0025 MCA ASW 5M CaCl2+0.05M Ca(NO3)2 118.6 0.00255 5.94 8,218 
LL030409812251.054 [DIRS 164185] KK001 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 75 0.00287 5.54 1,609 
LL030409812251.054 [DIRS 164185] KK001 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 75 0.00287 5.54 1,431 
LL030409812251.054 [DIRS 164185] KK001 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 75 0.00287 5.54 1,337 
LL030409812251.054 [DIRS 164185] KK004 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 75 0.00287 5.61 1,602 
LL030409812251.054 [DIRS 164185] KK004 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 75 0.00287 5.61 1,415 
LL030409812251.054 [DIRS 164185] KK004 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 75 0.00287 5.61 1,265 
LL030409812251.054 [DIRS 164185] KK002 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.79 1,147 
LL030409812251.054 [DIRS 164185] KK002 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.79 920 
LL030409812251.054 [DIRS 164185] KK002 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.79 820 
LL030409812251.054 [DIRS 164185] KK003 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.86 1,125 
LL030409812251.054 [DIRS 164185] KK003 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.86 919 
LL030409812251.054 [DIRS 164185] KK003 Prism ASW 5M CaCl2 + 0.5M Ca(NO3)2 90 0.00275 5.86 788 
LL030502212251.063 [DIRS 163456] JE 0027 MCA ASW 5M CaCl2 +1M Ca(NO3)2 121.8 0.00253 5.95 1,925 
LL030502212251.063 [DIRS 163456] JE 0027 MCA ASW 5M CaCl2 +1M Ca(NO3)2 121.8 0.00253 5.95 2,182 
LL030502212251.063 [DIRS 163456] JE 0027 MCA ASW 5M CaCl2 +1M Ca(NO3)2 121.8 0.00253 5.95 1,870 
LL030502212251.063 [DIRS 163456] JE 0027 MCA ASW 5M CaCl2 +1M Ca(NO3)2 121.8 0.00253 5.95 2,221 
LL030502212251.063 [DIRS 163456] JE 0026 MCA ASW 5M CaCl2 +1M Ca(NO3)2 123.7 0.00252 5.72 6,419 
LL030502212251.063 [DIRS 163456] JE 0026 MCA ASW 5M CaCl2 +1M Ca(NO3)2 123.7 0.00252 5.72 6,060 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-9 October 2004 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030502212251.063 [DIRS 163456] JE 0026 MCA ASW 5M CaCl2 +1M Ca(NO3)2 123.7 0.00252 5.72 6,089 
LL030502212251.063 [DIRS 163456] JE 0011 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2 118.8 0.00255 6.58 3,333 
LL030502212251.063 [DIRS 163456] JE 0011 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2 118.8 0.00255 6.58 2,544 
LL030502212251.063 [DIRS 163456] JE 0011 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2 118.8 0.00255 6.58 3,929 
LL030502212251.063 [DIRS 163456] JE 0012 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2 119.0 0.00255 6.62 2,616 
LL030502212251.063 [DIRS 163456] JE 0012 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2 119.0 0.00255 6.62 2,561 
LL030502212251.063 [DIRS 163456] JE 0012 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2 119.0 0.00255 6.62 3,005 
LL030502212251.063 [DIRS 163456] JE 0009 MCA ASW + Aged, 173 hrs at 
700C 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.69 947 
LL030502212251.063 [DIRS 163456] JE 0009 MCA ASW + Aged, 173 hrs at 
700C 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.69 879 
LL030502212251.063 [DIRS 163456] JE 0009 MCA ASW + Aged, 173 hrs at 
700C 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.69 584 
LL030502212251.063 [DIRS 163456] JE 0010 MCA ASW + Aged, 173 hrs at 
700C 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.73 1,289 
LL030502212251.063 [DIRS 163456] JE 0010 MCA ASW + Aged, 173 hrs at 
700C 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.73 1,628 
LL030502212251.063 [DIRS 163456] JE 0010 MCA ASW + Aged, 173 hrs at 
700C 1M CaCl2+1M Ca(NO3)2 104.8 0.00265 6.73 1,019 
LL030502212251.063 [DIRS 163456] JE 0016 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.05M Ca(NO3)2 119.2 0.00255 6.07 7,786 
LL030502212251.063 [DIRS 163456] JE 0016 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.05M Ca(NO3)2 119.2 0.00255 6.07 7,538 
LL030502212251.063 [DIRS 163456] JE 0016 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.05M Ca(NO3)2 119.2 0.00255 6.07 6,334 
LL030502212251.063 [DIRS 163456] JE 0015 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.05M Ca(NO3)2 119.8 0.00254 6.15 4,396 
LL030502212251.063 [DIRS 163456] JE 0015 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.05M Ca(NO3)2 119.8 0.00254 6.15 4,752 
LL030502212251.063 [DIRS 163456] JE 0015 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.05M Ca(NO3)2 119.8 0.00254 6.15 4,669 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IV-10 October 2004 
Source DTN Sample ID 
Sample 
Type 
Material 
Condition Environment 
Temp 
(C) 
1/T 
(1/K) pH 
Corrosion 
Rate (nm/yr) 
LL030502212251.063 [DIRS 163456] JE 0018 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.5M Ca(NO3)2 118.0 0.00256 6.54 2,237 
LL030502212251.063 [DIRS 163456] JE 0018 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.5M Ca(NO3)2 118.0 0.00256 6.54 2,119 
LL030502212251.063 [DIRS 163456] JE 0018 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.5M Ca(NO3)2 118.0 0.00256 6.54 1,547 
LL030502212251.063 [DIRS 163456] JE 0017 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.5M Ca(NO3)2 118.5 0.00255 6.51 1,438 
LL030502212251.063 [DIRS 163456] JE 0017 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.5M Ca(NO3)2 118.5 0.00255 6.51 1,487 
LL030502212251.063 [DIRS 163456] JE 0017 MCA ASW + Aged, 173 hrs at 
700C 5M CaCl2+0.5M Ca(NO3)2 118.5 0.00255 6.51 1,670 
Source DTNs: LL030309512251.042 [DIRS 163455], LL030502212251.063 [DIRS 163456], LL030409812251.054 [DIRS 164185]. 
NOTE: A measured room temperature pH of 4.14 for 5 M CaCl2 solutions tested at 120C (from the scientific notebook associated with DTN: 
LL030400112251.043 [DIRS 163466] (i.e., Ilevbare 2003 [DIRS 171329], p. 141) was used for high temperature and high CaCl2 solutions (Samples 
DEA595, DEA596, DEA599, and DEA3125). Also, a measured room temperature pH of 5.34 for 5 M CaCl2 plus 0.05 M Ca(NO3)2 solution tested at 
120C from DTN: LL030502212251.063 [DIRS 163456] was used for CaCl2 plus Ca(NO3)2 salt solutions (Samples DEA597, DEA598, DEA600, 
DEA3118, DEA3119, DEA3120, DEA3122, and DEA3127). 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-1 October 2004 
APPENDIX V 
LONG-TERM STEADY-STATE CORROSION POTENTIAL MEASUREMENTS OF 
ALLOY 22 SAMPLES USED IN THE CORROSION POTENTIAL MODEL AND 
ANALYSIS 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-3 October 2004 
V. LONG-TERM STEADY-STATE CORROSION POTENTIAL MEASUREMENTS OF ALLOY 22 SAMPLES USED IN 
THE CORROSION POTENTIAL MODEL AND ANALYSIS A) 
Cell 
Number Sample ID Sample Type 
Sample Initial 
Condition Environment 
Temperature 
(C) pH b) 
[Cl] c) 
(m) 
[NO3] c) 
(m) 
Exposure 
Time 
(days) d) 
Ecorr 
(mV SSC) d) 
1 DUB028 Welded Alloy 22 
U-Bend 
1,527 days (4+ 
Years) in LTCTF Aged LTCTF SAW 60 3.14 0.765 i) 0.372 i) 1,089 380 
1 DUB157 Welded Alloy 22 
U-Bend 
Untested, 600-grit 
surface polish Aged LTCTF SAW 60 3.14 0.765 i) 0.372 i) 1,089 408 
2 DUB052 Welded Alloy 22 
U-Bend 
1,512 days (4+ 
Years) in LTCTF Aged LTCTF SAW 90 4.17 0.809 i) 0.402 i) 892 288 e) 
2 DUB159 Welded Alloy 22 
U-Bend 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 4.17 0.809 i) 0.402 i) 892 387 
3 DUB112 Welded Alloy 22 
U-Bend 
1,464 days (4+ 
Years) in LTCTF Aged LTCTF SCW 90 10.91 0.214 i) 0.114 i) 1,089 -32 
3 DUB161 Welded Alloy 22 
U-Bend 
Untested, 600-grit 
surface polish Aged LTCTF SCW 90 10.91 0.214 i) 0.114 i) 1,089 -55 
4 
ARC22 U20A 
and ARC22 
U20B 
Wrought Alloy 
22 Double UBend 
407 days (1+ year) 
in Bench Top Fresh BSW 105 8.77 4.38 i) 2.63 i) 729 67 
4 DUB163 Welded Alloy 22 
U-Bend 
Untested, 600-grit 
surface polish Fresh BSW 105 8.77 4.38 i) 2.63 i) 729 13 
5 DUB128 Welded Alloy 22 
U-Bend 
1,460 days (4+ 
Years) in LTCTF Aged LTCTF SDW 60 9.66 0.0033 i) 0.000973 i) 1,089 54 
5 DUB160 Welded Alloy 22 
U-Bend 
Untested, 600-grit 
surface polish Aged LTCTF SDW 60 9.66 0.0033 i) 0.000973 i) 1,089 31 
6 DUB132 Welded Alloy 22 
U-Bend 
1,457 days (4+ 
Years) in LTCTF Aged LTCTF SDW 90 8.5 0.00325 i) 0.000313 i) 1,043 81 
6 DUB162 Welded Alloy 22 
U-Bend 
Untested, 600-grit 
surface polish Aged LTCTF SDW 90 8.5 0.00325 i) 0.000313 i) 1,043 108 
7 DUB088 Welded Alloy 22 
U-Bend 
1,495 days (4+ 
Years) in LTCTF Aged LTCTF SCW 60 10.24 b 0.206 0.116 277 21 f), h) 
7 DUB156 Welded Alloy 22 
U-Bend 
Untested, 600-grit 
surface polish Aged LTCTF SCW 60 10.24 b 0.206 0.116 277 -27 f), h) 
7N DEA2802 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 25 3.88 0.808 i) 0.408 i) 840 265 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-4 October 2004 
Cell 
Number Sample ID Sample Type 
Sample Initial 
Condition Environment 
Temperature 
(C) pH b) 
[Cl] c) 
(m) 
[NO3] c) 
(m) 
Exposure 
Time 
(days) d) 
Ecorr 
(mV SSC) d) 
7N DEA2807 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 25 3.88 0.808 i) 0.408 i) 840 258 
7N DEA2859 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 25 3.88 0.808 i) 0.408 i) 840 241 
8 DEA105 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 4.92 11.9878 0 894 -126 
8 DEA106 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 4.92 11.9878 0 894 -139 
8 DEA107 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 4.92 11.9878 0 894 -150 
8 DEA108 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 4.92 11.9878 0 894 -126 
8 DEA109 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 4.92 11.9878 0 894 -133 
9 DEA2797 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 401 
9 DEA2853 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 400 
9 DEA2881 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 401 
9 DEA2928 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 401 
9 DEA2940 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 401 
9 DEA3010 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 401 
9 DEA3014 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 398 
9 DEA3082 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SAW 90 2.8 0.782 i) 0.4 i) 876 400 
10 DEA2850 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 387 
10 DEA2851 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 382 
10 DEA2852 Wrought Alloy Untested, 600-grit Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 376 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-5 October 2004 
Cell 
Number Sample ID Sample Type 
Sample Initial 
Condition Environment 
Temperature 
(C) pH b) 
[Cl] c) 
(m) 
[NO3] c) 
(m) 
Exposure 
Time 
(days) d) 
Ecorr 
(mV SSC) d) 
22 Rod surface polish 
10 DEA2854 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 383 
10 DEA2855 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 385 
10 DEA2856 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 375 
10 DEA2857 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 378 
10 DEA2858 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Aged LTCTF SAW 90 3.83 0.838 i) 0.426 i) 834 383 
13 DEA3087 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 1 M CaCl2 + 1 M Ca(NO3)2 90 3.6 2.62 i) 2.58 i) 622 328 
13 DEA3088 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 1 M CaCl2 + 1 M Ca(NO3)2 90 3.6 2.62 i) 2.58 i) 622 334 
13 DEA3089 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 1 M CaCl2 + 1 M Ca(NO3)2 90 3.6 2.62 i) 2.58 i) 622 332 
13 DEA3090 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 1 M CaCl2 + 1 M Ca(NO3)2 90 3.6 2.62 i) 2.58 i) 622 324 
13 JE2033 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 1 M CaCl2 + 1 M Ca(NO3)2 90 3.6 2.62 i) 2.58 i) 458 363 
13 JE2034 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 1 M CaCl2 + 1 M Ca(NO3)2 90 3.6 2.62 i) 2.58 i) 458 347 
14 DEA2800 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.05 M 
Ca(NO3)2 90 4.37 11.6994 0.1186 697 148 
14 DEA2801 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.05 M 
Ca(NO3)2 90 4.37 11.6994 0.1186 697 278 
14 DEA2803 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.05 M 
Ca(NO3)2 90 4.37 11.6994 0.1186 697 57 
14 DEA2804 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.05 M 
Ca(NO3)2 90 4.37 11.6994 0.1186 697 104 
14 JE2035 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.05 M 
Ca(NO3)2 90 4.37 11.6994 0.1186 554 161 
14 JE2036 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.05 M 
Ca(NO3)2 90 4.37 11.6994 0.1186 554 205 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-6 October 2004 
Cell 
Number Sample ID Sample Type 
Sample Initial 
Condition Environment 
Temperature 
(C) pH b) 
[Cl] c) 
(m) 
[NO3] c) 
(m) 
Exposure 
Time 
(days) d) 
Ecorr 
(mV SSC) d) 
15 DEA2805 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 4.98 12.5934 1.2643 689 238 
15 DEA2806 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 4.98 12.5934 1.2643 689 190 
15 DEA2808 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 4.98 12.5934 1.2643 689 99 
15 DEA2809 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 4.98 12.5934 1.2643 689 89 
15 JE2037 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 4.98 12.5934 1.2643 554 229 
15 JE2038 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 4.98 12.5934 1.2643 554 282 
16 DEA2810 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SCW 90 10.94 0.205 i) 0.106 i) 394 -221 g) 
16 DEA2811 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SCW 90 10.94 0.205 i) 0.106 i) 394 -198 g) 
16 DEA2812 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish Fresh SCW 90 10.94 0.205 i) 0.106 i) 394 -175 g) 
16 JE2039 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish Fresh SCW 90 10.94 0.205 i) 0.106 i) 394 -177 g) 
16 JE2040 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish Fresh SCW 90 10.94 0.205 i) 0.106 i) 394 -174 g) 
16 JE2041 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish Fresh SCW 90 10.94 0.205 i) 0.106 i) 394 -168 g) 
17 DEA2813 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish SAW w/out Silicate 90 2.97 0.782 i) 0.4 i) 375 410 
17 DEA2814 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish SAW w/out Silicate 90 2.97 0.782 i) 0.4 i) 375 409 
17 DEA2815 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish SAW w/out Silicate 90 2.97 0.782 i) 0.4 i) 375 408 
17 JE2042 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish SAW w/out Silicate 90 2.97 0.782 i) 0.4 i) 375 414 
17 JE2043 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish SAW w/out Silicate 90 2.97 0.782 i) 0.4 i) 375 414 
17 JE2044 ASW Alloy 22 Untested, 600-grit SAW w/out Silicate 90 2.97 0.782 i) 0.4 i) 375 414 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-7 October 2004 
Cell 
Number Sample ID Sample Type 
Sample Initial 
Condition Environment 
Temperature 
(C) pH b) 
[Cl] c) 
(m) 
[NO3] c) 
(m) 
Exposure 
Time 
(days) d) 
Ecorr 
(mV SSC) d) 
Rod surface polish 
18 DEA2816 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 4 M NaCl 90 6.3 4.51 i) 0 328 -168 
18 DEA2817 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 4 M NaCl 90 6.3 4.51 i) 0 328 -161 
18 DEA2818 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 4 M NaCl 90 6.3 4.51 i) 0 328 -167 
18 JE2045 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 4 M NaCl 90 6.3 4.51 i) 0 328 -122 
18 JE2046 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 4 M NaCl 90 6.3 4.51 i) 0 328 -78 
18 JE2047 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 4 M NaCl 90 6.3 4.51 i) 0 328 -80 
Data below were not used due to exposure time less than 0.9 years 
19 DEA2822 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish BSW 105 10.49 4.38 i) 2.63 i) 194 -212 f) 
19 DEA2823 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish BSW 105 10.49 4.38 i) 2.63 i) 194 -194 f) 
19 JE2050 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish BSW 105 10.49 4.38 i) 2.63 i) 194 -222 f) 
19 JE2051 ASW Alloy 22 
Rod 
Untested, 600 grit 
surface polish BSW 105 10.49 4.38 i) 2.63 i) 194 -209 f) 
20 DEA2824 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 5.9 11.9878 0 301 -159 f) 
20 DEA2825 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 5.9 11.9878 0 255 -107 f) 
20 DEA2826 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 5.9 11.9878 0 301 -93.3 f) 
20 JE2052 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 5.9 11.9878 0 301 -2.55 f) 
20 JE2053 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 5.9 11.9878 0 255 8.1 f) 
20 JE2054 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 5 M CaCl2 120 5.9 11.9878 0 301 55.1 f) 
21 DEA2827 Wrought Alloy Untested, 600-grit 5 M CaCl2 + 0.5 M 90 5.9 12.5934 1.2643 267 405 f) 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 V-8 October 2004 
Cell 
Number Sample ID Sample Type 
Sample Initial 
Condition Environment 
Temperature 
(C) pH b) 
[Cl] c) 
(m) 
[NO3] c) 
(m) 
Exposure 
Time 
(days) d) 
Ecorr 
(mV SSC) d) 
22 Rod surface polish Ca(NO3)2 
21 DEA2828 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 5.9 12.5934 1.2643 267 390 f) 
21 DEA2829 Wrought Alloy 
22 Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 5.9 12.5934 1.2643 267 -20.4 f) 
21 JE2055 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 5.9 12.5934 1.2643 267 486 f) 
21 JE2056 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 5.9 12.5934 1.2643 267 486 f) 
21 JE2063 ASW Alloy 22 
Rod 
Untested, 600-grit 
surface polish 
5 M CaCl2 + 0.5 M 
Ca(NO3)2 90 5.9 12.5934 1.2643 267 487 f) 
NOTES: a Long-term corrosion potential data, exposure time, sample characteristics, and test environments and temperature were from DTN: 
LL040402212251.084 [DIRS 170097]. Only the data obtained using uncreviced specimens (U-bend and rods) were used. Of the rod specimens only 
those ones with wrought base metal and the as-welded (ASW) specimens were used. Welded plus aged samples were not used because the aging 
treatment was more severe (700C for 173 hours) than could reasonably be expected in the repository environment. 
b pH values of the test solutions were the pH at the end of the tests. If the pH at the end of the test was not available, the pH at the beginning of the test 
was used (DTN: LL040402212251.084 [DIRS 170097]). pH for Cell 7 is from DTN: LL031001023121.035 [DIRS 170502]. 
c Molal concentrations of chloride and nitrate ions of test solutions were the calculated values from DTN: LL030703723121.031 [DIRS 164184] or are 
from DTN: LL031001023121.035 [DIRS 170502]. If the calculated values were not available, the measured values were used from DTN: 
LL031001023121.035 [DIRS 170502]. 
d For the corrosion potential model and analysis, only the Ecorr data after an immersion time of 328 days and higher were used. The criteria of selection 
was based on one-year immersion (or a fraction equal or higher than 0.9). In some systems (Cell 8 (5 M CaCl2) in Figure 6-47) the Ecorr seemed to 
stabilize in the first 50 days of exposure; however, in other systems such as in Cell 14 (5 M CaCl2 + 0.05 M Ca(NO3)2) in Figure 6-47 Ecorr is not fully 
stable even after 2 years of exposure. That is, it is considered appropriate to use an average of one-year immersion time to be reasonably assured that 
the cells have stabilized. 
e Data not used in the long-term corrosion potential model and analysis since it was determined to be an outlier. 
f Data not used in the corrosion model and analysis since the exposure time was less than one year. 
g Ecorr data for Cell 16 is different than the ones reported in DTN: LL040402212251.084 [DIRS 170097] since the reported times are different. The time 
in DTN: LL040402212251.084 [DIRS 170097] is 259 days. The Ecorr data for Cell 16 in Appendix V was taken directly from DTN: 
LL040402112251.083 [DIRS 170283] for an exposure time of 394 days. 
h Ecorr from DTN: LL020711612251.017 [DIRS 161204]. 
i Values from DTN: LL031001023121.035 [DIRS 170502]. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VI-1 October 2004 
APPENDIX VI 
PROJECT ALLOY 22 CREVICE REPASSIVATION POTENTIAL DATA USED IN THE 
CRITICAL POTENTIAL MODEL IN THE ABSENCE OF NITRATE IONS 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VI-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VI-3 October 2004 
VI. PROJECT ALLOY 22 CREVICE REPASSIVATION POTENTIAL DATA USED IN THE CRITICAL POTENTIAL 
MODEL IN THE ABSENCE OF NITRATE IONS 
Source DTN a) Specimen 
ID 
Sample 
Type b) 
Material 
Condition b) Electrolyte Temperature 
(C) pH f) 
[Cl] 
(mol/kg 
water) e) 
[NO3] 
(mol/kg 
water) e) 
Ercrev 
(mV vs. SSC) 
c) 
LL030309512251.042 [DIRS 163455] DEA3262 MCA MA 1M NaCl 90 5.97 1.023 0.000 -53 
LL030309512251.042 [DIRS 163455] DEA3263 MCA MA 1M NaCl 90 5.97 1.023 0.000 -54 
LL030309512251.042 [DIRS 163455] DEA3267 MCA MA 1.25M NaCl 60 4.41 1.289 0.000 44 
LL030309512251.042 [DIRS 163455] DEA3268 MCA MA 1.25M NaCl 60 4.41 1.289 0.000 15 
LL030309512251.042 [DIRS 163455] DEA3269 MCA MA 1.25M NaCl 90 4.41 1.289 0.000 -66 
LL030309512251.042 [DIRS 163455] DEA3271 MCA MA 1.25M NaCl 90 4.41 1.289 0.000 -44 
LL030309512251.042 [DIRS 163455] DEA3182 MCA MA 1.25M CaCl2 60 5.83 2.582 0.000 117 
LL030309512251.042 [DIRS 163455] DEA3183 MCA MA 1.25M CaCl2 60 5.83 2.582 0.000 -33 
LL030309512251.042 [DIRS 163455] DEA3184 MCA MA 1.25M CaCl2 90 5.83 2.582 0.000 -65 
LL030309512251.042 [DIRS 163455] DEA3185 MCA MA 1.25M CaCl2 90 5.83 2.582 0.000 -49 
LL030309512251.042 [DIRS 163455] DEA3189 MCA MA 2.5M CaCl2 90 5.75 5.401 0.000 -124 
LL030309512251.042 [DIRS 163455] DEA3190 MCA MA 2.5M CaCl2 90 5.75 5.401 0.000 -122 
LL030400112251.043 [DIRS 163466] DEA3224 MCA MA 5 M CaCl2 60 4.33 11.988 0.000 -9 
LL030400112251.043 [DIRS 163466] DEA3225 MCA MA 5 M CaCl2 60 4.33 11.988 0.000 18 
LL030400112251.043 [DIRS 163466] DEA3226 MCA MA 5 M CaCl2 60 4.33 11.988 0.000 -31 
LL030400112251.043 [DIRS 163466] DEA3220 MCA MA 5 M CaCl2 75 4.33 11.988 0.000 -97 
LL030400112251.043 [DIRS 163466] DEA3223 MCA MA 5 M CaCl2 75 4.33 11.988 0.000 -78 
LL030400112251.043 [DIRS 163466] DEA3228 MCA MA 5 M CaCl2 75 4.33 11.988 0.000 -143 
LL030400112251.043 [DIRS 163466] DEA3233 MCA MA 5 M CaCl2 75 4.33 11.988 0.000 -137 
LL030400112251.043 [DIRS 163466] DEA3238 MCA MA 5 M CaCl2 75 4.14 11.988 0.000 -117 
LL030406212251.044 [DIRS 163467] DEA3278 MCA MA 5 M CaCl2 75 4.29 11.988 0.000 -139 
LL030406212251.044 [DIRS 163467] DEA3279 MCA MA 5 M CaCl2 75 4.29 11.988 0.000 -102 
LL030406212251.044 [DIRS 163467] DEA3280 MCA MA 5 M CaCl2 75 4.29 11.988 0.000 -16 
LL030406212251.044 [DIRS 163467] DEA3281 MCA MA 5 M CaCl2 75 4.29 11.988 0.000 -125 
LL030400112251.043 [DIRS 163466] DEA3216 MCA MA 5 M CaCl2 90 4.33 11.988 0.000 -184 
LL030400112251.043 [DIRS 163466] DEA3217 MCA MA 5 M CaCl2 90 4.33 11.988 0.000 -134 
LL030400112251.043 [DIRS 163466] DEA3218 MCA MA 5 M CaCl2 90 4.33 11.988 0.000 -141 
LL030400112251.043 [DIRS 163466] DEA3219 MCA MA 5 M CaCl2 90 4.33 11.988 0.000 -148 
LL030309512251.042 [DIRS 163455] DEA3167 MCA MA 5 M CaCl2 105 4.45 11.988 0.000 -195 
LL030309512251.042 [DIRS 163455] DEA3168 MCA MA 5 M CaCl2 105 4.45 11.988 0.000 -194 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VI-4 October 2004 
Source DTN a) Specimen 
ID 
Sample 
Type b) 
Material 
Condition b) Electrolyte Temperature 
(C) pH f) 
[Cl] 
(mol/kg 
water) e) 
[NO3] 
(mol/kg 
water) e) 
Ercrev 
(mV vs. SSC) 
c) 
LL021105112251.022 [DIRS 161138] DEA3208 MCA MA 5 M CaCl2 120 5.03 11.988 0.000 -168 
LL021105112251.022 [DIRS 161138] DEA3209 MCA MA 5 M CaCl2 120 5.03 11.988 0.000 -154 
LL030400112251.043 [DIRS 163466] DEA3234 MCA MA 5 M CaCl2 120 4.14 11.988 0.000 -168 
LL030400112251.043 [DIRS 163466] DEA3235 MCA MA 5 M CaCl2 120 4.14 11.988 0.000 -227 
LL030400112251.043 [DIRS 163466] DEA3237 MCA MA 5 M CaCl2 120 4.14 11.988 0.000 -201 
LL030409812251.054 [DIRS 164185] DEA3125 MCA MA 7 M CaCl2 130 4.14 d 19.228 0.000 -197 
LL030409812251.054 [DIRS 164185] DEA599 Disc MA 7 M CaCl2 130 4.14 d 19.228 0.000 -229 
LL030400112251.043 [DIRS 163466] JE0111 MCA ASW 5 M CaCl2 60 4.14 11.988 0.000 -51 
LL030400112251.043 [DIRS 163466] JE0112 MCA ASW 5 M CaCl2 60 4.14 11.988 0.000 -89 
LL030400112251.043 [DIRS 163466] JE0113 MCA ASW 5 M CaCl2 60 4.14 11.988 0.000 -51 
LL021105112251.022 [DIRS 161138] JE0106 MCA ASW 5 M CaCl2 75 5.10 11.988 0.000 -163 
LL021105112251.022 [DIRS 161138] JE0107 MCA ASW 5 M CaCl2 75 5.10 11.988 0.000 -160 
LL030400112251.043 [DIRS 163466] JE0040 MCA ASW 5 M CaCl2 75 4.14 11.988 0.000 -129 
LL030400112251.043 [DIRS 163466] JE0041 MCA ASW 5 M CaCl2 75 4.14 11.988 0.000 -117 
LL030400112251.043 [DIRS 163466] JE0042 MCA ASW 5 M CaCl2 75 4.14 11.988 0.000 -130 
LL030400112251.043 [DIRS 163466] JE0037 MCA ASW 5 M CaCl2 90 4.14 11.988 0.000 -189 
LL030400112251.043 [DIRS 163466] JE0038 MCA ASW 5 M CaCl2 90 4.14 11.988 0.000 -163 
LL030400112251.043 [DIRS 163466] JE0039 MCA ASW 5 M CaCl2 90 4.14 11.988 0.000 -175 
LL030502212251.063 [DIRS 163456] JE0022 MCA ASW 5 M CaCl2 120 5.03 11.988 0.000 -184 
LL030400112251.043 [DIRS 163466] JE0034 MCA ASW 5 M CaCl2 120 4.14 11.988 0.000 -165 
LL030400112251.043 [DIRS 163466] JE0035 MCA ASW 5 M CaCl2 120 4.14 11.988 0.000 -184 
LL030400112251.043 [DIRS 163466] JE0036 MCA ASW 5 M CaCl2 120 4.14 11.988 0.000 -185 
NOTES: a The sample characteristics and test environments are from the original source DTNs. 
b MCA = multiple crevice assembly, Disc = Disc sample, MA = mill annealed, ASW = as-welded. 
c The crevice repassivation potentials (Ercrev) are from DTN: LL030409512251.051 [DIRS 163462] and Section 6.4.4.2. 
d pH of the high chloride and high temperature solutions of DTN: LL030409812251.054 [DIRS 164185] was not reported. A measure 
room temperature pH of 4.14 for 5 M CaCl2 solutions tested at 120C (from the scientific notebook associated with DTN: 
LL030400112251.043 [DIRS 163466]( i.e., Ilevbare 2003 [DIRS 171329], p. 141) 7 M CaCl2 solutions tested at 130C (Samples 
DEA3125 and DEA599). Also, the measured room temperature pH of 5.34 for 5 M CaCl2 plus 0.05 M Ca(NO3)2 solution tested at 
120C from DTN: LL030502212251.063 [DIRS 163456] was used for CaCl2 plus Ca(NO3)2 salt solutions (Samples DEA3127, 
DEA598 and DEA600). 
e Molal concentrations of chloride and nitrate ions of test solutions are from DTN: LL030703723121.031 [DIRS 164184]. Solutions 
were considered to be completely dissociated 
f The pH values of all test solutions were measured at room temperature. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VII-1 October 2004 
APPENDIX VII 
CNWRA ALLOY 22 CREVICE REPASSIVATION POTENTIAL DATA USED IN THE 
CRITICAL POTENTIAL MODEL IN THE ABSENCE OF NITRATE IONS 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VII-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VII-3 October 2004 
VII. CNWRA ALLOY 22 CREVICE REPASSIVATION POTENTIAL DATA USED IN THE CRITICAL POTENTIAL 
MODEL IN THE ABSENCE OF NITRATE IONS 
Specimen ID 
Sample 
Type d) 
Material 
Condition d) Electrolyte 
Temperature 
(C) pH a) 
[Cl] 
(mol/kg 
water) b) 
[NO3] 
(mol/kg 
water) b) 
Ercrev (mV, 
vs. SCE) 
Ercrev (mV, 
vs. SSC) c) 
CNWRA MCA MA 0.5 M NaCl 105 8.00 0.510 0.000 -52 -10 
CNWRA MCA MA 0.5 M NaCl 125 8.00 0.510 0.000 -106 -64 
CNWRA MCA MA 0.5 M NaCl 125 8.00 0.510 0.000 -18 24 
CNWRA MCA MA 0.5 M NaCl 150 8.00 0.510 0.000 -155 -113 
CNWRA MCA MA 1.0 M NaCl 80 8.00 1.023 0.000 227 269 
CNWRA MCA MA 1.0 M NaCl 95 8.00 1.023 0.000 161 203 
CNWRA MCA MA 1.0 M NaCl 95 8.00 1.023 0.000 39 81 
CNWRA MCA MA 1.0 M NaCl 105 8.00 1.023 0.000 -54 -12 
CNWRA MCA MA 1.0 M NaCl 125 8.00 1.023 0.000 -171 -129 
CNWRA MCA MA 1.0 M NaCl 125 8.00 1.023 0.000 24 66 
CNWRA MCA MA 1.0 M NaCl 150 8.00 1.023 0.000 -216 -174 
CNWRA MCA MA 1.0 M NaCl 150 8.00 1.023 0.000 -202 -160 
CNWRA MCA MA 4.0 M NaCl 80 8.00 4.278 0.000 125 167 
CNWRA MCA MA 4.0 M NaCl 95 8.00 4.278 0.000 -57 -15 
CNWRA MCA MA 4.0 M NaCl 95 8.00 4.278 0.000 107 149 
CNWRA MCA MA 4.0 M NaCl 95 8.00 4.278 0.000 -98 -56 
CNWRA MCA MA 4.0 M NaCl 105 8.00 4.278 0.000 -143 -101 
CNWRA MCA MA 4.0 M NaCl 125 8.00 4.278 0.000 -175 -133 
CNWRA MCA MA 4.0 M NaCl 150 8.00 4.278 0.000 -192 -150 
CNWRA MCA ASW 0.005 M NaCl 95 6.00 0.006 0.000 271 313 
CNWRA MCA ASW 0.05 M NaCl 95 6.00 0.050 0.000 129 171 
CNWRA MCA ASW 0.1 M NaCl 95 6.00 0.100 0.000 214 256 
CNWRA MCA ASW 0.5 M NaCl 95 8.00 0.510 0.000 -10 32 
CNWRA MCA ASW 0.5 M NaCl 125 8.00 0.510 0.000 -59 -17 
CNWRA MCA ASW 1.0 M NaCl 125 8.00 1.023 0.000 -71 -29 
CNWRA MCA ASW 4.0 M NaCl 95 8.00 4.278 0.000 -38 4 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VII-4 October 2004 
Specimen ID 
Sample 
Type d) 
Material 
Condition d) Electrolyte 
Temperature 
(C) pH a) 
[Cl] 
(mol/kg 
water) b) 
[NO3] 
(mol/kg 
water) b) 
Ercrev (mV, 
vs. SCE) 
Ercrev (mV, 
vs. SSC) c) 
CNWRA MCA ASW 4.0 M NaCl 95 8.00 4.278 0.000 -159 -117 
CNWRA MCA ASW 4.0 M NaCl 125 8.00 4.278 0.000 -216 -174 
CNWRA MCA ASW 4.0 M NaCl 150 8.00 4.278 0.000 -195 -153 
Source: Brossia et al. 2001 [DIRS 159836], Table A-1. 
NOTES: a)The pH of test solutions was measured at the room temperature. 
b)Molal concentrations of chloride and nitrate ions of test solutions are from DTN: LL030703723121.031 [DIRS 164184]. 
Solutions were considered to be completely dissociated. 
c)The crevice repassivation potentials reported are with respect to the saturated calomel reference electrode (SCE). The 
Projects crevice repassivation potentials were reported with respect to the Ag/AgCl (SSC) reference electrode in saturated KCl 
solution. At 25C the SSC reference electrode is 199 mV more noble than the standard hydrogen electrode (SHE), and 42 mV 
less noble than the SCE. The SCE scale potentials were converted to the SSC scale potentials by adding 42 mV. 
d)MA = mill annealed, ASW = as-welded, MCA = multiple crevice assembly. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-1 October 2004 
APPENDIX VIII 
PROJECT ALLOY 22 CREVICE REPASSIVATION POTENTIAL DATA USED IN THE 
CRITICAL POTENTIAL MODEL IN THE PRESENCE OF NITRATE IONS 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-3 October 2004 
VIII. PROJECT ALLOY 22 CREVICE REPASSIVATION POTENTIAL DATA USED IN THE CRITICAL POTENTIAL 
MODEL IN THE PRESENCE OF NITRATE IONS 
Source DTN 
Specimen 
ID 
Sample 
Type a) 
Metallurgical 
Condition a) Electrolyte 
T 
(C) pH b) 
Cl c) 
(mol/kg 
water) 
NO3 c) 
(mol/kg 
water) 
Ercrev d), e) 
(mV SSC) 
o 
rcrev E 
Median 
(mV SSC) 
- . 3 NO 
rcrev E 
(mV SSC) 
LL030409812251.054 
[DIRS 164185] DEA3105 MCA MA 1.25 M CaCl2 + 0.0125 M 
Ca(NO3)2 60 6.47 2.57 0.026 61 87.32 -26.32 
LL030409812251.054 
[DIRS 164185] DEA3109 MCA MA 1.25 M CaCl2 + 0.125 M 
Ca(NO3)2 90 6.41 2.612 0.263 -72 -8.57 -63.43 
LL030409812251.054 
[DIRS 164185] DEA3123 MCA MA 5 M CaCl2 + 0.5 M Ca(NO3)2 105 4.86 12.593 1.264 108 -165.21 273.21 
LL030409812251.054 
[DIRS 164185] DEA3124 MCA MA 5 M CaCl2 + 0.5 M Ca(NO3)2 105 4.86 12.593 1.264 133 -165.21 298.21 
LL030502212251.063 
[DIRS 163456] JE0024 MCA ASW 5 M CaCl2 + 0.05 M Ca(NO3)2 120 5.34 11.699 0.119 -264 -182.54 -81.46 
LL030409812251.054 
[DIRS 164185] DEA598 Disc MA 6 M CaCl2 + 0.6 M Ca(NO3)2 120 5.34 16.323 1.64 37 -194.47 231.47 
LL030409812251.054 
[DIRS 164185] DEA3127 MCA MA 7 M CaCl2 + 0.7 M Ca(NO3)2 130 5.34 20.815 2.073 32 -221.50 253.50 
LL030409812251.054 
[DIRS 164185] DEA600 Disc MA 7 M CaCl2 + 0.7 M Ca(NO3)2 130 5.34 20.815 2.073 24 -221.50 245.50 
LL040402212251.084 
[DIRS 170097] JE3209 MCA ASW 1 m NaCl + 0.05 m KNO3 60 5.38 1 0.05 94 128.36 -34.46 
LL040402212251.084 
[DIRS 170097] JE3225 MCA ASW 1 m NaCl + 0.05 m KNO3 100 5.38 1 0.05 -119 -19.48 -99.62 
LL040402212251.084 
[DIRS 170097] JE3227 MCA ASW 1 m NaCl + 0.05 m KNO3 80 5.38 1 0.05 -52 54.44 -106.24 
LL040402212251.084 
[DIRS 170097] JE3236 MCA ASW 1 m NaCl + 0.05 m KNO3 100 5.38 1 0.05 -122 -19.48 -102.92 
LL040402212251.084 
[DIRS 170097] JE3241 MCA ASW 1 m NaCl + 0.05 m KNO3 60 5.38 1 0.05 348 128.36 219.84 
LL040402212251.084 
[DIRS 170097] JE3244 MCA ASW 1 m NaCl + 0.05 m KNO3 80 5.38 1 0.05 26 54.44 -28.24 
LL040402212251.084 
[DIRS 170097] JE3205 MCA ASW 1 m NaCl + 0.15 m KNO3 60 5.13 1 0.15 303 122.04 180.54 
LL040402212251.084 
[DIRS 170097] JE3213 MCA ASW 1 m NaCl + 0.15 m KNO3 80 5.13 1 0.15 290 48.12 241.78 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-4 October 2004 
Source DTN 
Specimen 
ID 
Sample 
Type a) 
Metallurgical 
Condition a) Electrolyte 
T 
(C) pH b) 
Cl c) 
(mol/kg 
water) 
NO3 c) 
(mol/kg 
water) 
Ercrev d), e) 
(mV SSC) 
o 
rcrev E 
Median 
(mV SSC) 
- . 3 NO 
rcrev E 
(mV SSC) 
LL040402212251.084 
[DIRS 170097] JE3214 MCA ASW 1 m NaCl + 0.15 m KNO3 60 5.13 1 0.15 550 122.04 427.56 
LL040402212251.084 
[DIRS 170097] JE3219 MCA ASW 1 m NaCl + 0.15 m KNO3 80 5.13 1 0.15 330 48.12 281.58 
LL040402212251.084 
[DIRS 170097] JE3220 MCA ASW 1 m NaCl + 0.15 m KNO3 100 5.13 1 0.15 15 -25.80 41.00 
LL040402212251.084 
[DIRS 170097] JE3237 MCA ASW 1 m NaCl + 0.15 m KNO3 100 5.13 1 0.15 -65 -25.80 -39.00 
LL040402212251.084 
[DIRS 170097] JE3212 MCA ASW 1 m NaCl + 0.5 m KNO3 60 5.32 1 0.5 349 126.84 221.86 
LL040402212251.084 
[DIRS 170097] JE3216 MCA ASW 1 m NaCl + 0.5 m KNO3 60 5.32 1 0.5 600 126.84 473.16 
LL040402212251.084 
[DIRS 170097] JE3218 MCA ASW 1 m NaCl + 0.5 m KNO3 80 5.32 1 0.5 305 52.92 252.48 
LL040402212251.084 
[DIRS 170097] JE3233 MCA ASW 1 m NaCl + 0.5 m KNO3 80 5.32 1 0.5 344 52.92 290.88 
LL040402212251.084 
[DIRS 170097] JE3235 MCA ASW 1 m NaCl + 0.5 m KNO3 100 5.32 1 0.5 365 -21.00 385.50 
LL040402212251.084 
[DIRS 170097] JE3202 MCA ASW 1 m NaCl + 0.5 m KNO3 100 5.32 1 0.5 254 -21.00 274.50 
LL040402212251.084 
[DIRS 170097] JE1771 MCA ASW 3.5 m NaCl + 0.175 m KNO3 60 5.53 3.5 0.175 -7 41.10 -47.80 
LL040402212251.084 
[DIRS 170097] JE3221 MCA ASW 3.5 m NaCl + 0.175 m KNO3 100 5.53 3.5 0.175 -132 -75.96 -56.14 
LL040402212251.084 
[DIRS 170097] JE3232 MCA ASW 3.5 m NaCl + 0.175 m KNO3 80 5.53 3.5 0.175 -79 -17.43 -61.57 
LL040402212251.084 
[DIRS 170097] JE3234 MCA ASW 3.5 m NaCl + 0.175 m KNO3 80 5.53 3.5 0.175 -85 -17.43 -67.27 
LL040402212251.084 
[DIRS 170097] JE3239 MCA ASW 3.5 m NaCl + 0.175 m KNO3 100 5.53 3.5 0.175 -104 -75.96 -27.64 
LL040402212251.084 
[DIRS 170097] JE3204 MCA ASW 3.5 m NaCl + 0.175 m KNO3 60 5.49 3.5 0.175 -73 40.09 -112.82 
LL040402212251.084 
[DIRS 170097] JE3264 MCA ASW 3.5 m NaCl + 0.35 m KNO3 80 5.59 3.5 0.35 55 -15.91 70.91 
LL040402212251.084 
[DIRS 170097] JE3211 MCA ASW 3.5 m NaCl + 0.525 m KNO3 60 5.49 3.5 0.525 269 40.09 228.51 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-5 October 2004 
Source DTN 
Specimen 
ID 
Sample 
Type a) 
Metallurgical 
Condition a) Electrolyte 
T 
(C) pH b) 
Cl c) 
(mol/kg 
water) 
NO3 c) 
(mol/kg 
water) 
Ercrev d), e) 
(mV SSC) 
o 
rcrev E 
Median 
(mV SSC) 
- . 3 NO 
rcrev E 
(mV SSC) 
LL040402212251.084 
[DIRS 170097] JE1773 MCA ASW 3.5 m NaCl + 0.525 m KNO3 100 5.49 3.5 0.525 -85 -76.97 -8.26 
LL040402212251.084 
[DIRS 170097] JE3229 MCA ASW 3.5 m NaCl + 0.525 m KNO3 80 5.49 3.5 0.525 322 -18.44 340.84 
LL040402212251.084 
[DIRS 170097] JE3230 MCA ASW 3.5 m NaCl + 0.525 m KNO3 60 5.49 3.5 0.525 565 40.09 524.61 
LL040402212251.084 
[DIRS 170097] JE3231 MCA ASW 3.5 m NaCl + 0.525 m KNO3 80 5.49 3.5 0.525 489 -18.44 507.24 
LL040402212251.084 
[DIRS 170097] JE3242 MCA ASW 3.5 m NaCl + 0.525 m KNO3 100 5.49 3.5 0.525 -96 -76.97 -19.13 
LL040402212251.084 
[DIRS 170097] JE3266 MCA ASW 3.5 m NaCl + 0.70 m KNO3 80 5.52 3.5 0.7 290 -17.68 307.68 
LL040402212251.084 
[DIRS 170097] JE3267 MCA ASW 3.5 m NaCl + 0.70 m KNO3 80 5.52 3.5 0.7 323 -17.68 340.68 
LL040402212251.084 
[DIRS 170097] JE3268 MCA ASW 3.5 m NaCl + 1.05 m KNO3 80 5.59 3.5 1.05 378 -15.91 393.91 
LL040402212251.084 
[DIRS 170097] JE3269 MCA ASW 3.5 m NaCl + 1.05 m KNO3 80 5.59 3.5 1.05 256 -15.91 271.91 
LL040402212251.084 
[DIRS 170097] JE3206 MCA ASW 3.5 m NaCl + 1.75 m KNO3 80 5.49 3.5 1.75 290 -18.44 308.54 
LL040402212251.084 
[DIRS 170097] JE3207 MCA ASW 3.5 m NaCl + 1.75 m KNO3 100 5.49 3.5 1.75 600 -76.97 676.97 
LL040402212251.084 
[DIRS 170097] JE3208 MCA ASW 3.5 m NaCl + 1.75 m KNO3 100 5.49 3.5 1.75 319 -76.97 395.97 
LL040402212251.084 
[DIRS 170097] JE3222 MCA ASW 3.5 m NaCl + 1.75 m KNO3 60 5.49 3.5 1.75 520 40.09 479.51 
LL040402212251.084 
[DIRS 170097] JE3243 MCA ASW 3.5 m NaCl + 1.75 m KNO3 60 5.49 3.5 1.75 303 40.09 262.41 
LL040402212251.084 
[DIRS 170097] JE3246 MCA ASW 3.5 m NaCl + 1.75 m KNO3 80 5.49 3.5 1.75 600 -18.44 618.44 
LL040402212251.084 
[DIRS 170097] JE3210 MCA ASW 6 m NaCl + 0.3 m KNO3 60 5.4 6 0.3 -18 -1.35 -16.35 
LL040402212251.084 
[DIRS 170097] JE3217 MCA ASW 6 m NaCl + 0.3 m KNO3 80 5.4 6 0.3 -95 -53.27 -41.93 
LL040402212251.084 
[DIRS 170097] JE3223 MCA ASW 6 m NaCl + 0.3 m KNO3 100 5.4 6 0.3 -120 -105.18 -15.12 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-6 October 2004 
Source DTN 
Specimen 
ID 
Sample 
Type a) 
Metallurgical 
Condition a) Electrolyte 
T 
(C) pH b) 
Cl c) 
(mol/kg 
water) 
NO3 c) 
(mol/kg 
water) 
Ercrev d), e) 
(mV SSC) 
o 
rcrev E 
Median 
(mV SSC) 
- . 3 NO 
rcrev E 
(mV SSC) 
LL040402212251.084 
[DIRS 170097] JE3228 MCA ASW 6 m NaCl + 0.3 m KNO3 80 5.4 6 0.3 -97 -53.27 -43.83 
LL040402212251.084 
[DIRS 170097] JE3201 MCA ASW 6 m NaCl + 0.3 m KNO3 100 5.4 6 0.3 -88 -105.18 16.96 
LL040402212251.084 
[DIRS 170097] JE3215 MCA ASW 6 m NaCl + 0.9 m KNO3 100 5.37 6 0.9 -85 -105.94 20.64 
LL040402212251.084 
[DIRS 170097] JE3240 MCA ASW 6 m NaCl + 0.9 m KNO3 100 5.37 6 0.9 -40 -105.94 65.94 
LL040402212251.084 
[DIRS 170097] JE3245 MCA ASW 6 m NaCl + 0.9 m KNO3 60 5.37 6 0.9 350 -2.11 351.71 
LL040402212251.084 
[DIRS 170097] JE3248 MCA ASW 6 m NaCl + 0.9 m KNO3 80 5.37 6 0.9 311 -54.03 365.13 
LL040402212251.084 
[DIRS 170097] JE3203 MCA ASW 6 m NaCl + 0.9 m KNO3 80 5.37 6 0.9 27 -54.03 80.71 
LL040402212251.084 
[DIRS 170097] JE1772 MCA ASW 6 m NaCl + 3 m KNO3 60 5.36 6 3 600 -2.37 602.37 
LL040402212251.084 
[DIRS 170097] JE3224 MCA ASW 6 m NaCl + 3 m KNO3 100 5.36 6 3 298 -106.19 404.19 
LL040402212251.084 
[DIRS 170097] JE3226 MCA ASW 6 m NaCl + 3 m KNO3 60 5.36 6 3 600 -2.37 602.37 
LL040402212251.084 
[DIRS 170097] JE3238 MCA ASW 6 m NaCl + 3 m KNO3 80 5.36 6 3 286 -54.28 340.28 
LL040402212251.084 
[DIRS 170097] JE1775 MCA ASW 6 m NaCl + 3 m KNO3 80 5.36 6 3 600 -54.28 654.28 
LL040402212251.084 
[DIRS 170097] JE3247 MCA ASW 6 m NaCl + 3 m KNO3 100 5.36 6 3 600 -106.19 706.19 
LL040402212251.084 
[DIRS 170097] JE3270 MCA ASW 10 m CaCl2 + 0.5 m Ca(NO3)2 100 5.34 20 1 -39 -164.62 125.62 
LL040402212251.084 
[DIRS 170097] JE3284 MCA ASW 10 m CaCl2 + 0.5 m Ca(NO3)2 100 5.34 20 1 -41 -164.62 123.62 
LL040402212251.084 
[DIRS 170097] JE3276 MCA ASW 10 m CaCl2 + 1.5 m Ca(NO3)2 100 5.34 20 3 13 -164.62 177.62 
LL040402212251.084 
[DIRS 170097] JE3285 MCA ASW 10 m CaCl2 + 1.5 m Ca(NO3)2 100 5.34 20 3 18 -164.62 182.62 
LL040402212251.084 
[DIRS 170097] JE3287 MCA ASW 10 m CaCl2 + 5 m Ca(NO3)2 100 5.34 20 10 600 -164.62 764.62 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-7 October 2004 
Source DTN 
Specimen 
ID 
Sample 
Type a) 
Metallurgical 
Condition a) Electrolyte 
T 
(C) pH b) 
Cl c) 
(mol/kg 
water) 
NO3 c) 
(mol/kg 
water) 
Ercrev d), e) 
(mV SSC) 
o 
rcrev E 
Median 
(mV SSC) 
- . 3 NO 
rcrev E 
(mV SSC) 
LL040402212251.084 
[DIRS 170097] JE3277 MCA ASW 12 m CaCl2 + 0.6 m Ca(NO3)2 130 5.34 24 1.2 -40 -225.73 185.73 
LL040402212251.084 
[DIRS 170097] JE3278 MCA ASW 12 m CaCl2 + 0.6 m Ca(NO3)2 130 5.34 24 1.2 -39 -225.73 186.73 
LL040402212251.084 
[DIRS 170097] JE3272 MCA ASW 12 m CaCl2 + 1.8 m Ca(NO3)2 130 5.34 24 3.6 13 -225.73 238.73 
LL040402212251.084 
[DIRS 170097] JE3273 MCA ASW 12 m CaCl2 + 1.8 m Ca(NO3)2 130 5.34 24 3.6 17 -225.73 242.73 
LL040402212251.084 
[DIRS 170097] JE3271 MCA ASW 12 m CaCl2 + 6 m Ca(NO3)2 130 5.34 24 12 600 -225.73 825.73 
LL040402212251.084 
[DIRS 170097] JE3279 MCA ASW 12 m CaCl2 + 6 m Ca(NO3)2 130 5.34 24 12 600 -225.73 825.73 
LL040402212251.084 
[DIRS 170097] JE3274 MCA ASW 18 m CaCl2 + 0.9 m Ca(NO3)2 160 5.34 36 1.8 11 -282.63 293.63 
LL040402212251.084 
[DIRS 170097] JE3282 MCA ASW 18 m CaCl2 + 0.9 m Ca(NO3)2 160 5.34 36 1.8 7 -282.63 289.63 
LL040402212251.084 
[DIRS 170097] JE3280 MCA ASW 18 m CaCl2 + 2.7 m Ca(NO3)2 160 5.34 36 5.4 239 -282.63 521.63 
LL040402212251.084 
[DIRS 170097] JE3283 MCA ASW 18 m CaCl2 + 2.7 m Ca(NO3)2 160 5.34 36 5.4 64 -282.63 346.63 
LL040402212251.084 
[DIRS 170097] JE3275 MCA ASW 18 m CaCl2 + 9 m Ca(NO3)2 160 5.34 36 18 600 -282.63 882.63 
LL040402212251.084 
[DIRS 170097] JE3281 MCA ASW 18 m CaCl2 + 9 m Ca(NO3)2 160 5.34 36 18 600 -282.63 882.63 
NOTES: aMCA = multiple crevice assembly, Disc = Disc sample, MA = mill annealed, ASW = as-welded. 
bA measured room temperature pH of 5.34 for 5 M CaCl2 plus 0.05 M Ca(NO3)2 solution tested at 120C from DTN: LL030502212251.063 [DIRS 163456] 
was used for CaCl2 plus Ca(NO3)2 salt solutions. All pH values were measured at room temperature. 
cMolal concentrations of chloride and nitrate ions of test solutions for samples for DEA3105, DEA3109, DEA3123, DEA3124, JE0024, DEA598, DEA3127, 
DEA600 are from DTN: LL030703723121.031 [DIRS 164184]. 
dCrevice repassivation potential values for samples DEA3105, DEA3109, DEA3123, DEA3124, and JE0024 are from DTN: LL030409512251.051 [DIRS 
163462]. Crevice repassivation potential values for DEA598, DEA3127, DEA600 are from the analysis documented in Section 6.4.4.2. Crevice repassivation 
potential values for the remaining samples are in DTN: LL040402212251.084 [DIRS 170097]. 
eA default value of +600 mV versus SSC is used for the crevice repassivation potential for those samples with a NO3/Cl ratio of 0.5 and when there was no 
observable localized corrosion or the reverse scan crossed the forward scan above the passive region. 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 VIII-8 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-1 October 2004 
APPENDIX IX 
MATHCAD WORKSHEETS FOR REGRESSION ANALYSIS OF THE CORROSION 
POTENTIAL MODEL AND CREVICE REPASSIVATION POTENTIAL MODEL AND 
FOR LOCALIZED CORROSION SUSCEPTIBILITY ANALYSES 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-2 October 2004 
INTENTIONALLY LEFT BLANK 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-3 October 2004 
IX. MATHCAD WORKSHEETS FOR REGRESSION ANALYSIS OF THE 
CORROSION POTENTIAL MODEL AND CREVICE REPASSIVATION POTENTIAL 
MODEL AND FOR LOCALIZED CORROSION SUSCEPTIBILITY ANALYSES 
IX.1 ERCREV_UNCANALYSIS.MCD 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-4 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-5 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-6 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-7 October 2004 
IX.2 DERCREV_UNCANALYSIS.MCD 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-8 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-9 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-10 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-11 October 2004 
IX.3 ECORR UNCANALYSIS.MCD 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-12 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-13 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-14 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-15 October 2004 
IX.4 ERCREV_V_ECORR.MCD 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-16 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-17 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-18 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-19 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-20 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-21 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-22 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-23 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-24 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-25 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-26 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-27 October 2004 
General Corrosion and Localized Corrosion of Waste Package Outer Barrier 
ANL-EBS-MD-000003 REV 02 IX-28 October 2004