Application of Tuned Mass Damper to Mitigation of the Seismic Responses of Electrical Equipment in Nuclear Power Plants

Abstract

A tuned mass damper (TMD) was developed for mitigating the seismic responses of electrical equipment inside nuclear power plants (NPPs), in particular, the response of an electrical cabinet. A shaking table test was performed, and the frequency and damping ratio were extracted, to confirm the dynamics of the cabinet. Electrical cabinets with and without TMDs were modeled while using SAP2000 software (Version 20, Computers and Structures, NY, USA) that was based on the results. TMDs were designed while using an optimization method and the equations of Den Hartog, Warburton, and Sadek. The numerical models were verified while using the shaking table test results. A sinusoidal sweep wave was applied as input to identify the vibration characteristics of the electrical cabinet over a wide frequency range. Applying various seismic loads that were adjusted to meet the RG 1.60 design response spectrum of 0.3 g then validated the control performance of the TMD. The minimum and maximum response spectrum reduction rates of the designed TMDs were 44.7% and 62.9%, respectively. Further, the amplification factor of the electrical cabinet with the TMD was decreased by 53%, on average, with the proposed optimization method. In conclusion, TMDs can be considered to be an effective way of enhancing the seismic performance of the electrical equipment inside NPPs.

Shaking Table Tests of Lead Inserted Small-Sized Laminated Rubber Bearing for Nuclear Component Seismic Isolation

“…There may be many ways to increase the seismic capacity of individual nuclear facility components [1][2][3], but applying the customized seismic isolators to individual nuclear components can be one of the effective approaches [4,5].…”

“…In this study, the shaking table tests of the full-scale LRBs developed in previous studies are carried out and their seismic isolation performance and dynamic characteristics are investigated through a well-established test matrix. The test conditions included in the test matrix are established to investigate (1) three levels of the seismic load, i.e., OBE (Operating Basis Earthquake), SSE (Safe Shutdown Earthquake), BDBE (Beyond Design Basis Earthquake), (2) damping function of the lead plugin continuous aftershock conditions, (3) consistent fabrication quality of small-sized LRBs, (4) extreme behavior of LRB, and (5) confirm the LRB design parameters. The used input motions in shaking table tests correspond to the typical floor response spectrum at 137 ft elevation of the nuclear power plant building structure, where the seismic isolation target components are expected to be located.…”

Active Mass Damper for Reducing Wind and Earthquake Vibrations of a Long-Period Bridge

“…Den Hartog [3] proposed the TMD to optimize the frequency and damping ratios for harmonic loads; since then, the TMD has been applied by many researchers in various fields such as buildings, bridges, and industrial facilities to compensate for various external forces [4][5][6][7]. Many researchers have studied developing and applying TMDs to reduce the vibration of bridges subjected to wind loads [8][9][10][11].…”

Seismic Vulnerability of Cabinet Facility with Tuned Mass Dampers Subjected to High- and Low-Frequency Earthquakes

“…As long as the structure behaves within the linear range of behavior, which is the case in the present study, this shortcoming is less pronounced. In the field of nuclear engineering, the TMD systems have been popularly used to mitigate the seismic response of structures [33][34][35][36][37]. For instance, Kwag et al developed multiple TMDs to reduce the vibration of the piping system in NPPs due to earthquakes [34,37].…”

“…Tan et al [39] used TMDs to reduce the seismic responses of piping systems. Cho et al [33] used a TMD to improve the seismic response of an electric facility.…”