Enhancement of seismic resilience of piping systems in nuclear power plants using steel coil damper

Abstract

After the accident at Fukushima, it has become more a mandatory to enhance the safety level of nuclear power plants (NPPs). It has been suggested that the piping systems in NPPs should be improved as part of measures to mitigate severe accidents that may occur when the earthquake ground input motion exceeds the level of the design basis earthquake (DBE). In this study, a steel coil damper (SCD) has been proposed to reduce the vibration of the piping system and ensure the safety of the NPP when a seismic event exceeds the DBE. This study developed an analytical model and design method for the SCD. The basic mechanical characteristics of the SCD were verified through experiments on the specimens designed and manufactured according to design equations developed in this study. The proposed analytical model of SCD is compared with the mechanical characteristics obtained from the experiments. Test results agree well with the analytical mechanical characteristic of the SCD. The actual seismic margin of the piping system with SCDs was evaluated by the analyses. The study results prove that the proposed damper is effective at maintaining the function and ensuring the safety of the NPP under extreme conditions.