The structural behavior of radioactive waste disposal facilities may be greatly influenced by earthquakes through ground shaking and earthquake-induced ground evaluation of radioactive waste repositories. Therefore, a comprehensive understanding of computational models considering the effects of discontinuities and an improvement of structural analysis methods are essential in order to predict properly the dynamic behavior of underground rock caverns subjected to seismic loadings. The purpose of this study is to examine the structural behavior of rock cavern within discontinuous rock masses subjected to dynamic loadings with the objective that the results of this study will become a basis for understanding the effects of ground motion associated with earthquakes on underground radioactive waste disposal facilities. This report is divided into three parts. In the first part, computational models for discontinuous rock masses and equations of motion for a rigid block model are discussed. In the second part, the distinct element program written for the static and dynamic analysis of discontinuous rock masses is presented. A few practical examples of structural analyses of rock caverns within discontinuous rock masses subjected to dynamic loadings using the distinct element computer program are presented in the third part of this report. (Author).