The methodology of drop analysis for KORAD-21 spent fuel dry cask storage

抄録

The subject of this study is KORAD-21, a multipurpose dry cask storage capable of carrying out transportation, storage and disposal. The purpose of this study is to develop a methodology for engineering evaluation that sufficient structural safety can be maintained under various accident scenario conditions that can occur during storage and transportation. Especially, the structural response of the dry cask storage in drop situation was analyzed based on the finite element model. The responses of drop scenarios are investigated using an explicit nonlinear dynamic FE simulation with a three-dimensional detailed model of dry cask storage via commercial FE code LS-DYNA and Explicit dynamics of ANSYS. For the analysis efficiency, two FE models were constructed in consideration of the symmetry of geometry and load. First, the quarter model was constructed because the geometry and load were symmetrical in four directions in the case of 9m vertical drop. In the case of 9m horizontal drop and inclined drop, half model was constructed because the geometry and load were symmetric in both left and right directions. Both models applied symmetry constraints on the planes of symmetry. The analysis was performed at the initial velocity of 13.29m/s, which is the velocity just before the dry cask storage hit the floor. For the conservative analysis, the floor where the cask collides applied rigid body model to avoid penetration or energy absorption. The results of the 1/3 scaled model test and the analytical results of this study were found to be similar and consistent in trend. The validated analysis results can be used to evaluate the structural safety of the cask itself, and furthermore, the FE model can serve as the basis for the evaluation of cracks and corrosion under the dynamic load of drop accident scenario.