Demonstration of the Vibration Control Performance of Coil Spring-viscous Damper Systems by Measuring the Vibration of an Emergency Diesel Generator

Abstract: The purpose of this study is to evaluate vibration characteristics according to the foundation type of an emergency diesel generator (EDG) of a nuclear power plant (NPP). For the purpose of this study, EDGs whose types are the same but whose foundation types are different were selected and measured for their operational vibrations. The target EDG systems were located in Yonggwang unit 5 and Ulchin unit 3 in Korea. Both EDG systems are the 16PC2–5V400 model type which was manufactured by the SEMT Pielstick corporation. The foundation systems of the Yonggwang 5 and Ulchin 3 units were an anchor bolt system and a Coil Spring-Viscous Damper system, respectively. The vibrations were measured in the case of before and during an operation for the two kinds of EDG system. A total of eight accelerometers were used for the vibration measurements. Six of the accelerometers were used for the foundation system, one accelerometer for the EDG body and the remaining accelerometer was for the isolated floor. The relative displacements between the isolated floor and foundation system were also measured to determine the complete movement of the EDG system in the case of using the Coil Spring-Viscous Damper system. The vibration reduction effects were evaluated and compared with the vibration responses for the foundation and the isolated floor, before and during an operation for the vibration measurement cases. The results of this research revealed that the Coil Spring-Viscous Damper system can reduce a vibration by over 90%. Although the Coil Spring-Viscous Damper system induced a rolling movement for the whole system, this movement of the whole EDG system was more stable when compared to that of an anchor bolt system