Seismic Assessment Of Nuclear Power Plants Containment And Internal Structure Concidering SSI

Nuclear energy can be used as a crucial way for solving the energy crisis in thefuture. China is an energy-shortage country, and the recoverable reserves like the coal,petroleum as well as the natural gas are limited and nonrenewable. Nuclear power iscurrently being developed vigorously in our country.40%of the world-wide nuclearpower plants are being constructed in China. The study of the seismic performance ofthe containment of nuclear power plants, internal equipment as well as the plant system isdirectly related to the peaceful operation of the nuclear power industry in our country.The performance-based seismic evaluation of the nuclear power plants is now in itsbeginning stage, and there is a need to perform the seismic capacity evaluation for thenuclear power plants using performance-based assessment methodology.In this study, the fragilities of the containment, internal structure, the whole nuclearplant and the system considering the soil-structure-interaction (SSI) are analyzed. In orderto investigate the influence of soil parameters on the dynamic response and damageprobability of component and system, an extensive parametric study has been conducted.The main contents of this paper are as follows:(1) A simplified model for representing a nuclear power plant is established. Andthis simplified model is then employed in the modal analysis to determine thefundamental period of the structure. A simplified model considering the SSI effect isbuilt and the effect of the SSI on a nuclear power plant structure was taken into accountaccording to the simplified model.(2) The seismic demand analysis of the internal equipment and containment areperformed. The fragility curves under the condition of rigid foundation as well as theselected soil parameters are obtained and compared.(3) The internal equipment, containment and the whole nuclear power plant areoptimized regarding the earthquake intensity when the structure failure probability of50%is used as the optimization index. The optimization surfaces are obtained when thestructure is subjected to the action of pulse-like ground motions and non-pulse-likeground motions, and the corresponding results are compared.(4) The function damage, function loss of nuclear power plant and nuclear leakageare studied systematically. The vulnerability curves of the system are obtained and thesoil parameters are optimized. And the results of non-pulse ground motions and pulseground motions are compared.