FINAL REPORT TOTAL SYSTEM PERFORMANCE ASSESSMENT PEER REVIEW PANEL
Front Matter
Title PageCONTENTS
EXECUTIVE SUMMARY A. INTRODUCTION B. KEY FINDINGS C. TSPA-VA METHODOLOGY D. FUTURE ACTIONS TO IMPROVE THE TSPA E. SPECIFIC TECHNICAL OBSERVATIONS AND FINDINGS Advances and Improvements in the TSPA-VA Analysis Key Role of Infiltration and Seeps Analysis Key Role of the Waste Package Disruptive Events Potentially Non-Conservative Approaches Data and Research Needs
I. Introduction
A. NATURE OF TSPA PEER REVIEW PROCESS B. CONTENT OF PANEL REPORTS Interim Reports Final Report
II. Main Findings
A. RELIABILITY OF THE TSPA-VA RESULTS Key Points Elements of a Credible Analysis B. ADVANCES AND IMPROVEMENTS IN THE TSPA-VA ANALYSIS C. KEY ROLE OF THE WASTE PACKAGE Corrosion Resistance Need for Data Wet Waste Packages Use of the TSPA to Evaluate Design Options D. KEY ROLE OF INFILTRATION AND SEEPS ANALYSIS E. POTENTIALLY NON-CONSERVATIVE ASPECTS OF THE ANALYSIS Cladding Soil Buildup in Biosphere Analysis F. POTENTIALLY CONSERVATIVE ASPECTS OF THE ANALYSIS Transport through Penetrations in Waste Packages Retention of Radionuclides in Alteration Products of Spent Fuel Potential Sorption of Technetium and Iodine G. POTENTIALLY IMPORTANT BUT OMITTED PROCESSES Expansion of Steel Corrosion Products Hydrogen Embrittlement of Zirconium Cladding Stress Corrosion Cracking H. DATA NEEDS Fundamental Data Testing Models I. INSIGHTS FROM THE TSPA-VA
III. THE TSPA-VA METHODOLOGY
A. EXPECTATIONS FOR THE TSPA-VA Differing Objectives for the TSPA-VA and the TSPA-LA Inherent Uncertainties in the Assessment B. METHODOLOGY Overall Framework of the Analysis Use of Model Abstractions Uncertainty and Sensitivity Analyses Use of Expert Elicitations Use of Expected Values C. COMPLEXITIES OF THE SYSTEM AND OF ITS COMPONENTS Modeling of Coupled Processes Limitations of the Component Models D. MANAGING COMPLEXITIES AND COMPONENT MODEL LIMITATIONS Conclusions and Recommendations E. OVERALL CONCLUSIONS ABOUT THE TSPA-VA METHODOLOGY
IV. COMPONENT MODELS OF TSPA-VA
A. THE UNSATURATED ZONE UNDER INITIAL CONDITIONS Infiltration Rate Hydrologic Properties Seepage B. THERMOHYDROLOGY Background Coupled Effects TSPA-VA Approach C. NEAR-FIELD GEOCHEMICAL ENVIRONMENT Background TSPA-VA Approach General Findings D. WASTE PACKAGE DEGRADATION Overview of Waste Package Performance Base Case and Alternate Designs Environmental Conditions At, On, and Within the Waste Packages WAPDEG and Individual Corrosion Models Waste Package Sensitivity Analyses Physical Events and Processes Data and Related Research Needs E. THE ROLE OF FUEL CLADDING Background TSPA-VA Approach General Findings Future Work F. WASTE FORM DEGRADATION Spent Nuclear Fuel Borosilicate glass G. RADIONUCLIDE MOBILIZATION Solubility-Limited Radionuclide Concentrations Formation of Secondary Phases Colloid Formation EBS Transport H. UNSATURATED ZONE TRANSPORT I. SATURATED ZONE FLOW AND TRANSPORT Lack of Field Data Incomplete Characterization of the Site Streamtube Approach J. BIOSPHERE Use of Site-Specific Data Uncertainties and Conservatisms Soil Adsorption of Radionuclides K. EARTHQUAKES, VOLCANISM, CRITICALITY, HUMAN INTRUSION, AND CLIMATE CHANGE Earthquakes Seismic Rockfall Analysis Volcanism Criticality Human Intrusion Climate Change
Appendix A: Specific Comments on Sub-System Models of the NFGE
MODELS OF INCOMING GAS, WATER AND COLLOIDS Gas Water Colloids MODELING OF IN-DRIFT GAS MODELING OF IN-DRIFT WATER/SOLID CHEMISTRY In-Drift Colloid Model In-Drift Microbial Communities Model
APPENDIX B: PEER REVIEW PLAN
APPENDIX C: PEER REVIEW PANEL
ACRONYMS AND ABBREVIATIONS
REFERENCES
LIST OF FIGURES
Figure IV-1. Calculated seepage fraction and seep flow rate as functions of percolation flux (Figure 3-13 of TSPA-VA). Figure IV-2. Simulated vertical temperature profiles at Yucca Mountain (from Haukwa et al, 1998). Figure IV-3. Development of precipitate cap over repository as indicated by fracture porosity ratio change (from Hardin, 1998). Figure IV-4. Logic diagram for waste package degradation model (Figure 3-44, TSPA-VA). Figure IV-5. Information needs for the waste package degradation model-WAPDEG (Figure 5-5 Chapter 5 of Technical Basis Documents). Figure A-1. Schematic stability relations among the minerals found in typical hydrothermal systems. Kao: kaolinite, Ser: sericite, NM: Na-montmorillonite, Ab: albite, Kf: K-feldspar (after Browne, 1978).