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The Effects of the Glass Surface Area/Solution Volume Ratio on Glass Corrosion: a Critical Review

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The Effects of the Glass Surface Area/Solution Volume Ratio on Glass Corrosion: a Critical Review ANL-94/34 Chemical Technology The Effects of the Glass Surface Division Chemical Technology Area/Solution Volume Ratio on Division Chemical Technology Glass Corrosion: A Critical Review Division by W. L. Ebert Argonne National Laboratory, Argonne, Illinois 60439 operated by The University of Chicago for the United States Department of Energy under Contract W-31-109-Eng-38 OF TWS DOCUMEKT ,S UN Argonne National Laboratory, with facilities in the states of Illinois and Idaho, is owned by the United States government, and operated by The University of Chicago under the provisions of a contract with the Department of Energy. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or pro- cess disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Reproduced from the best available copy. Available to DOE and DOE contractors from the Office of Scientific and Technical Information P.O. Box 62 Oak Ridge. TN 3783! Prices available from (615) 576-8401 Available to the public from the National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield. VA 22161 Distribution Category: High-Level Radioactive Waste Disposal in Tuff (UC-814) ANL-94/34 ARGONNE NATIONAL LABORATORY 9700 South Cass Avenue Argonne, Illinois 60439 THE EFFECTS OF THE GLASS SURFACE AREA/SOLUTION VOLUME RATIO ON GLASS CORROSION: A CRITICAL REVIEW by William L. Ebert Chemical Technology Division MASTER DIS««iTlON Of TH« K-W" >» '•>•«••>"" TABLE OF CONTENTS Page ABSTRACT 1 SUMMARY 2 1.0 INTRODUCTION 4 2.0 DESCRIPTION OF GLASS STRUCTURE 7 2.1 Chemical Description of Glass Corrosion 9 2.1.1 Alkali Release 9 2.1.2 Water Diffusion 12 2.1.3 Dealkalization 12 2.1.4 Release of Network-Forming Elements 16 2.1.5 Glass Corrosion 17 2.2 Experimental Measures of the Extent of Glass Corrosion 17 2.3 Measurement of the Corrosion Rate 21 2.4 A Phenomenological Model of Corrosion Behavior 22 2.5 Standard Test Methods 25 2.5.1 Static Tests 27 2.5.1.1 MCC-1 Test 27 2.5.1.2 Product Consistency Test 32 2.5.1.3 MCC-3 Solubility Test 34 2.5.1.4 Argonne National Laboratory Vapor Hydration Tests 35 2.5.1.5 Buffered Solution/pH-Stat Tests 36 2.5.2 Dynamic Tests 37 2.5.2.1 Soxhlet Tests 37 2.5.2.2 Single-Pass Flow-Through Tests 37 2.5.2.3 Periodic Replenishment Tests 38 2.6 Measurement of Surface Area 40 2.7 Effect of Surface Finish 46 2.8 Measurement of Leachant Volume 47 2.9 Changes in SA/V as the Glass Corrodes 48 3.0 OBSERVED EFFECTS OF THE SOLUTION CHEMISTRY ON GLASS CORROSION 51 3.1 Tests Conducted to Distinguish between Mass Transport and Surface Reaction Effects 52 3.2 Observed Effects of Silicic Acid Concentration on Glass Corrosion 60 3.3 Observed Effects of the Leachate pH on Glass Corrosion 63 3.4 Observed Effects of Other Species on Glass Corrosion 72 3.5 Glass Corrosion under Silicon Saturated Conditions: The Residual Rate 73 3.6 Summary 77 in TABLE OF CONTENTS (contd.) 4.0 OBSERVED EFFECTS OF THE GLASS SURFACE AREA- TO-SOLUTION VOLUME RATIO IN STATIC TESTS 78 4.1 Effects of SA/V on the Solution Chemistry 78 4.2 Applicability of (SA/V)t as a Scaling Factor 82 4.3 Modeling the Effects of the Solution pH 92 4.4 Effects of SA/V on Alteration Layers 95 4.5 Tests Conducted to Attain Highly Concentrated Solutions 97 4.6 Summary 98 5.0 OBSERVED EFFECTS OF THE FLOW RATES IN DYNAMIC LEACH TESTS 99 6.0 DETERMINATION OF MODEL PARAMETERS FROM LABORATORY TESTS 106 7.0 EFFECTS OF SA/V ON RADIONUCLIDE DISPOSITION 115 7.1 Summary of the Chemistries of Tc, U, Np, Pu, and Am 117 7.2 Experimental Measurement of Radionuclide Release 119 7.2.1 Tests Conducted under Dilute Solution Conditions 119 7.2.2 Tests under Concentrated Solution Conditions 127 7.3 Actinide-Bearing Secondary Phases 128 7.4 Effects of Other Materials on Actinide Disposition 129 7.5 Summary 131 8.0 SUMMARY OF CRITICAL REVIEW OF EFFECTS OF SA/V ON GLASS CORROSION AND DISCUSSION OF REMAINING UNCERTAINTIES 132 8.1 Observed Corrosion Behavior 132 8.2 Modeling 133 8.3 Testing 133 8.4 SA/V 134 8.5 Flow 135 8.6 Remaining Issues 135 9.0 ANL TASK "RELATIONSHIP BETWEEN HIGH SA/V TESTS ANDMCC-1" 138 9.1 Technical Approach 138 9.2 Observed Effects of the SA/V on the Leachate Chemistry 141 9.2.1 LeachatepH 141 9.2.2 Glass Matrix Components 143 9.2.3 Observed Effects of SA/V on the Behavior of Radionuclides 153 9.3 Effects of the SA/V on the Alteration of the Glass Surface 161 9.4 Summary 165 IV TABLE OF CONTENTS (contd.) Page ACKNOWLEDGMENTS 166 REFERENCES 167 APPENDIX A. Definitions 187 APPENDIXB. Glass Compositions 189 APPENDIX C. Derivation of Rate Equation 191 APPENDIX D. Data Generated in the Study of the Relationship between High SA/V Tests and MCC-1 Tests 196 LIST OF FIGURES No. Title Page 1. Schematic Plot of the Fraction of =SiO Sites Associated with Protons or Other Cations as a Function of pH in 1 x 10~3 M Cation Solutions 10 2. Schematic Plot of the Fraction of =A1O", sBO, and sSi Sites Associated with Protons or Sodium as a Function of pH in 1 x 10"3M Cation Solutions 11 3. Measured Concentrations of Sodium, Hydrogen, and Excess Hydrogen at the Surface after Corrosion in Silicate Solution at 100°C 15 4. Product Consistency Tests Showing Nonstoichiometric Release of Glass Components 19 5. Schematic Plot Showing Instantaneous and Integrated Rates for a Specific Reaction Time "A" on a Typical Release Curve 21 6. Schematic Plot Showing Corrosion Behavior as the Corrosion Progresses 23 7. Measured Boron Concentrations in 28-Day Replacement Tests 40 8. Photomicrographs of -100+200 Mesh Size Fraction of Crushed Glass 43 9. Test Results for Different Size Fractions of Crushed Glass 44 10. Photomicrograph of Corroded SRL EA Glass Grain 49 11. Variations of MCC-1 Test with Glass A 53 12. Variations of MCC-1 Test with Glass B 54 13. Variations of MCC-1 Test with Glass C 55 14. Variations of MCC-1 Test with MCC 76-68 and C31 -3 Glass in Deionized Water 56 15. Variations of MCC-1 Test with MCC 76-68 and C31-3 Glass in MgCl2 Solution 57 16. Measured Extent of Corrosion vs. Time for Tests with Variously Treated Samples 58 17. Boron Release from PNL 76-68 Glass vs. Silicic Acid Concentration Synthetic Solutions and Groundwaters 61 VI LIST OF FIGURES (contd.) No. Title Page 18. Glass Corrosion Rate vs. the Ion Activity Product of Silicic Acid 61 , 19. Release of B, Na, C, Al, and Si from CSG Glass as a Function of Time at pH 6 and pH 10 65 20. Corrosion Rate of CSG Glass vs. pH 66 i 21. Corrosion Ratio of R7T7 Glass vs. pH 66 22. Alkali Release Rates from Simple Glasses vs. pH 67 23. Silicon Release from Fused Silica vs. pH and Silicon Release vs. pH from 33Li2O67Si02 and 15K2085Si02 Glasses 69 24. Release of Sodium, Calcium, and Si from 20Na2O20CaO60Si02 vs. pH 70 25. Release of Aluminum and Sodium vs. pH from Glass 1 and from Glass 2 71 26. Effects of Si, Al, Mg, and Ca on CSG Dissolution 72 27. Normalized Mass Loss of Boron and Silicon from C-31-3EC Glass in NaCl Solutions at 200°C 74 28. Normalized Sodium Mass Loss and pH vs. Time at Different SA/V Ratios 80 29. Measured pH and Si in Tests with PNL 76-68 Glass Conducted in Deionized Water at Different SA/V Ratios 81 30. Concentration vs. (SA/V)t for Release of Boron and Silicon from PNL 76-68 Glass at 90°C 83 31. Measured Boron Concentrations in Tests with SRL 165 Glass vs. (SA/V)t 83 32. Boron Release vs. (SA/V)t in Tests of SRP Black Frit Glass at Various S A/V Ratios 84 33. Measured Silicic Acid Concentration vs. (SA/V)t for Tests with SRL 165 Glass at SA/V Ratios of 7.9 and 85 m"1 85 34. Measured Silica Concentration vs. Log Time for Tests with Li2O2Si02 Glass 86 35. Corrosion of HW-39 Glass at Various SA/V Ratios 87 vn LIST OF FIGURES (contd.) No. Title Page 36. Measured Concentrations of Boron and Silica in Tests with R7T7 Glass 89 37. Measured Boron Concentration vs. (SA/V)t and Measured pH vs. Time for Tests with SRL 202 Glass at SA/V Ratios of 10, 2000, and 20,000 ml 91 38. Normalized Mass Loss vs. Reaction Time for Tests with SRL 200R and SRL 200S Glasses at 20,000 m-1 93 39.
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