Seismic Fragility Evaluation of Main Steam Piping of Isolated APR1400 NPP Considering the Actual Failure Mode

An isolation system installed in a nuclear power plant (NPP) could increase seismic safety during events. On the other hand, more significant relative displacement may occur due to system. The risk be increased case of an interface piping that connects isolated and nonisolated structures. Therefore, it is necessary consider systems when evaluating isolated-NPPs. This study performed fragility analysis with APR1400 plants main steam piping. pipe connecting auxiliary building turbine building. failure mode for was defined as cracks caused by leakage. experimental numerical results quantified leak-through crack point damage index. curves are suggested based on peak ground acceleration between buildings.