INVESTIGATION OF SHOCK LOADING FROM CONTAINER WITH SPENT FUEL ON THE BEARING STRUCTURE OF SPENT FUEL STORAGE FACILITY

摘要

This investigation covers analysis and response of the bearing structure of Spent Fuel Storage Facility (SFSF) in Kozloduy NPP under hypothetic accident with container CONSTOR® drop on structural elements during crane transport operations in the facility. During such accident container exerts dynamic shock loading with high intensity on the bearing structure. With respect to transport path, height at which the container is moved and structural scheme of the building elements, several accidental load cases have been chosen and analyzed. As criteria for the selection was considered structural and dynamic response of the building elements and systems, participating in the load transfer. Shock loading from container drop can be classified as high intensity dynamic load and depends on drop height, container mass and on dynamic characteristics (response) of the bearing structure and soil base and includes their stiffness, activated mass and ductility. Two analytical approaches and models were used to investigate and estimate the structural response of the building of SFSF to this shock loading. First approach is based on theoretical and numeric analysis for single degree of freedom model and the results were compared. For this model the dynamic loading was considered as short-term impulse force of interaction. Displacements and internal forces are obtained under the solution of the differential equation of the body motion depending on time (time history analysis). Almost full coincidence of the resulis at the stated initial dynamic loading was obtained. Second approach is based on Finite Element analysis with Software Code SAP 2000. Local models with multi degrees of freedom for different structural elements and structural sub systems were generated, as well as a global spatial model for the whole building structure. All geometry parameters, material parameters masses and loads on the structural elements were defined. Soil base was modeled as elastic sub-grade reaction under foundation slab and spring supports under single foundations. The loading was defined as time history load function in determined nodes/elements. Maximum values of displacements and forces were obtained. Based on the results all respective structural elements were checked for adequate bearing capacity. Conclusion: Based on the conducted investigations and analyses the consequences from container drop to separate structural elements and to the whole building structure of the SFSF were defined and estimated.