Seismic Analysis of Waste Packages Stacked in Radioactive Waste Disposal Silos

Abstract

Dynamic load from an earthquake would be a critical detrimental factor that could debilitate the structural stability of radioactive waste packages disposed at the repository. This study evaluated the seismic stability of the stacked radioactive waste disposal container columns at the silo-type Gyeongju repository, Korea, based on the actual ground motions measured at the repository site in 2016. The ground motions were converted to within-rock motions in an underground repository at 130 m below through deconvolution analyses by using uniform hazard spectra of Korea. The overall amplitudes of the within-rock motions are smaller than the ground motions. The structural stability of the stacked radioactive waste disposal container column during the seismic loads was computationally investigated with the within-rock motions. It is unlikely for the container columns to collide with each other due to the small enough horizontal displacement even under a 1-in-2,500 years earthquake event. Also, the containers are expected to not be plastically deformed and damaged. The seismic analysis approaches and results can contribute to confidence in the safety of a silo-type repository by applying seismic data assuring the reliability and be utilized to design a deep geological repository for high-level radioactive wastes.