Re-evaluation of the required thickness of the carbon steel overpack for high-level radioactive waste disposal in Japan based on the latest scientific and engineering knowledge

Abstract

The required thickness of the carbon steel overpack for high-level radioactive waste geological disposal in Japan was re-evaluated based on the latest scientific and engineering knowledge. The re-evaluation of the required thickness was carried out for the concept of vertical emplacement in a hard rock system (which requires the greatest overpack thickness). The re-evaluation was carried out to meet design requirements for corrosion resistance, structural integrity and the prevention/reduction of detrimental radiation effects on corrosion resistance. The re-evaluated minimum thicknesses to assure a lifetime greater than 1000 years were 122 mm for the flat end plate and 91 mm for the cylindrical body. Therefore, the applicability of the reference thickness (190 mm) for the overpack was reconfirmed. This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.