[en] Under this Annex, a research program on the near-field performance assessment related to the geological disposal of radioactive waste will be carried out at the Lawrence Livermore National Laboratory (LLNL) in close collaboration with the Power Reactor and Nuclear Fuel Development Corporation of Japan (PNC). This program will focus on activities that provide direct support for PNC's near-term and long-term needs that will, in turn, utilize and further strengthen US capabilities for radioactive waste management. The work scope for two years will be designed based on the PNC's priorities for its second progress report (the H12 report) of research and development for high-level radioactive waste disposal and on the interest and capabilities of the LLNL. The work will focus on the chemical modeling for the near-field environment and long-term mechanical modeling of engineered barrier system as it evolves. Certain activities in this program will provide for a final iteration of analyses to provide additional technical basis prior to the year 2000 as determined in discussions with the PNC's technical coordinator. The work for two years will include the following activities: Activity 1: Chemical Modeling of EBS Materials Interactions--Task 1.1 Chemical Modeling of Iron Effects on Borosilicate Glass Durability; and Task 1.2 Changes in Overpack and Bentonite Properties Due to Metal, Bentonite and Water Interactions. Activity 2: Thermodynamic Database Validation and Comparison--Task 2.1 Set up EQ3/6 to Run with the Pitzer-based PNC Thermodynamic Data Base; Task 2.2 Provide Expert Consultation on the Thermodynamic Data Base; and Task 2.3 Provide Analysis of Likely Solubility Controls on Selenium. Activity 3: Engineered Barrier Performance Assessment of the Unsaturated, Oxidizing Transient--Task 3.1 Apply YMIM to PNC Transient EBS Performance; Task 3.2 Demonstrate Methods for Modeling the Return to Reducing Conditions; and Task 3.3 Evaluate the Potential for Stress Corrosion Cracking in PNC Waste Packages. Activity 4: Coupled Displacement and Degradation Analysis of Carbon Steel Overpack Embedded in Bentonite--Task 4.1 Demonstration of NIKE-2D/ALE-3D Mesh Adaptation Capability; Task 4.2 Demonstration of NIKE-2D/ALE-3D Code Capability to Compute Realistic Repository Problems; Task 4.3 Implementation and Verification of the Cam Clay Model in NIKE-2D/ALE-3D Code; and Task 4.4 Estimation of the Timing and Spatial Distribution of Rewetting