Study on vibration behaviors of engineered barrier system

High-level radioactive wastes have been buried underground by packing into a strong sealed container made from carbon steel (over-pack) with buffer material (bentonite). The engineered barrier system constructed with an overpack and buffer materials must be resistant to earthquakes as well as invasion of groundwater for a long period. Therefore, seismic evaluation of barrier system for earthquakes is indispensable especially in Japan to keep its structural safety. Here, the effects of earthquake vibration on the engineered barrier systems were investigated experimentally. Random-wave vibration and practical seismic wave one were loaded for the systems and fundamental data were obtained. For the former vibration the response characteristics of both engineered barrier models constructed with overpack and bentonite were non-linear. For the latter one, the stress in bentonite was increased in proportion to the vibration level. (M.N.)