Technical development for geological disposal of high-level radioactive wastes

Technical developments for geological disposal of high-level radioactive wastes materials research and design technique for engineered barriers (overpack and buffer material) were studied to evaluate more reliable disposal systems for high-level radioactive wastes. A lifetime prediction model for the maximum corrosion depth of carbon steel was developed. A preferable alloys evaluation method for crevice corrosion was established for titanium. Swelling pressure and water permeability of bentonite as a buffer material was measured, and coupled hydro-thermo-mechanical analysis code for bentonite was also studied. The CIP (cold isostatic pressing) method for monolithically formed buffer material was tested. A concept study on operation equipment for the disposal site was performed. Activities of microorganisms involved in underground performance were investigated. (author)