Year
2010
Abstract
Casks for long-term dry interim storage of spent fuel and high active waste from reprocessing are well qualified and licensed for storage periods of up to 40 years in Germany. Other countries like the U.S. and Japan may have different time periods and generally, these periods are mainly dominated by administrative boundaries and not determined by technical aspects. But, nevertheless, more investigation of cask materials and components is necessary to gain additional data for the evaluation of applied longer storage periods. Important topics in that field are the long-term stability of metal seals as the main component for the safe enclosure of the radioactive cask inventory and the performance of polymer components for neutron shielding purposes. Some years ago, BAM has been starting an investigation program with metal seals of the Helicoflex® type to study static, cyclic and dynamic loads concerning their influence on leak- tightness. E.g. long-term static tests have been carried out at room temperature and 150 °C for one year so far to study creeping effects as well. Present test results will be presented and discussed in the paper. Furthermore, BAM investigates the performance of polymer components in particular under thermal and radiation effects. Irradiated polymers used as neutron shielding cask components have been analyzed with different methods like, e. g., FT-Infrared-Spectroscopy (FT-IR), Thermo Mechanical Analysis (TMA), and Differential Scanning Calorimetry (DSC). General aspects and experimental results with respect to modifications in material structures are discussed.