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

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 427 ◽  
Author(s):  
Sung Gook Cho ◽  
Seongkyu Chang ◽  
Deokyong Sung
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Shaking Table Test ◽  
Response Spectrum ◽  
Electrical Equipment ◽  
Optimization Method ◽  
Tuned Mass Damper ◽  
Shaking Table ◽  
Seismic Responses ◽  
Mass Damper

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.

A Shaking Table Test for the Evaluation of Floor Response Spectrum of Seismic Isolated NPP Structure

2016 ◽  
Author(s):  
Min Kyu Kim ◽  
Jung Han Kim
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Shaking Table Test ◽  
Response Spectrum ◽  
Low Frequency ◽  
Shaking Table ◽  
Frame Structure ◽  
Design Spectrum ◽  
Seismic Input

The development of a floor response spectrum (FRS) is very important for a seismic risk assessment of nuclear power plants. In the case of non-isolated nuclear power plants, the methodology regarding FRS generation has already been developed. But in the case of seismic isolated NPP structure, the methodology for developing floor response spectrum is not been determined yet. Therefore, in this study, shaking table tests for a seismic isolated frame structure were performed for the development of the floor response spectrum. For the shaking table test, a two-story artificial frame structure was manufactured. For the isolation devices, a lead rubber bearing and an EradiQuake system (EQS) were used. An artificial input seismic motion, which was generated for the NRC Reg. guide 1.60 design spectrum, was used but low-frequency range should be cut off for a decrease of the shaking table displacement. One-, two-, and three-dimensional seismic input motions were considered for the assessment of the horizontal bidirectional and vertical directional effects. Through this test, whether a horizontal bi-directional seismic input can make a difference in the floor response, and moreover, whether the vertical input motion can make a change in the horizontal floor response, were investigated.

SEISMIC RESPONSE AND NUMERICAL VERIFICATION FOR A 1/25 SCALED-DOWN REINFORCED CONCRETE REACTOR BUILDING SPECIMEN

2015 ◽  
Vol 39 (3) ◽  
pp. 479-488
Author(s):  
Wei-Ting Lin ◽  
Yuan-Chieh Wu ◽  
An Cheng ◽  
Hui-Mi Hsu
Keyword(s):  
Reinforced Concrete ◽  
Nuclear Power ◽  
Power Plants ◽  
Shaking Table Test ◽  
Dynamic Properties ◽  
Real Life ◽  
Full Scale ◽  
Shaking Table ◽  
Numerical Verification ◽  
Reactor Building

In recent years, full-scale specimens for seismic test were important to safety assessment of the structure in nuclear power plants but the full-scale tests were not easy to realize due to the limited capable of the existing shaking table capacity. In Taiwan, it was first time to construct a 1/25 scale-down reinforced concrete reactor building specimen in a nuclear power plant and conduct to study the dynamic properties using shaking table test. The specimen was with a length of 2.9 m, width of 2.9 m, height of 2.9 m and weight of 28 tons and cast using the non-demoulding technology and self-consolidating concrete. The entirety structure was composed of a primary containment (thickness of 10 cm), a secondary containment (thickness of 7.5 cm) and three floors (thickness of 30 and 15 cm). The comparison of measured and calculated results demonstrate that ETABS numerical model was satisfactory and can be further used for numerical shaking table tests and real life structures.

Study on Piping Response Under Multiple Excitation: Part 1 — Triple Shaking Table Test of Piping Having Three-Supporting Points

2013 ◽  
Author(s):  
Tomoyoshi Watakabe ◽  
Naoaki Kaneko ◽  
Shigekazu Aida ◽  
Akihito Otani ◽  
Makoto Moriizumi ◽  
...  
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Nuclear Power ◽  
Shaking Table Test ◽  
Response Spectrum ◽  
Response Spectra ◽  
Shaking Table ◽  
Response Analysis ◽  
3 Dimensional ◽  
Floor Response Spectra

The piping in a nuclear power plant is laid across multiple floors of a single building or two buildings, which are supported at many points. As the piping is excited by multiple inputs from the supporting points during an earthquake, seismic response analysis by multiple excitations is needed to obtain the exact seismic response of the piping. However, few experiments involving such multiple excitations have been performed to verify the validity of multiple excitation analysis. Therefore, analysis of the seismic design of piping in Japan is performed by the enveloped Floor Response Spectrum (FRS), which covers all floor response spectra at all supporting points. The piping response estimated by enveloped FRS is conservative in most cases compared with the actual seismic response by multiple excitations. To perform rational seismic design and evaluation, it is important to investigate the seismic response by multiple excitations and verify the validity of the analysis method by multiple-excitation test. This paper reports on the result of the shaking test using triple uni-axial shaking tables and a 3-dimensional piping model (89.1mm in diameter and 5.5mm thickness). The piping model was fixed to three shaking tables, meaning three. Different inputs were possible. By the shaking test, dynamic behavior under multiple excitations was confirmed, and data to verify multiple-excitation analysis was obtained.

Inertia Mass Damper and its Application

2017 ◽  
Author(s):  
Katsuaki Sunakoda ◽  
Issei Yamazaki
Keyword(s):  
Earthquake Engineering ◽  
Nuclear Power ◽  
Power Plants ◽  
Experimental Studies ◽  
Shaking Table ◽  
Bridge Engineering ◽  
Historical Background ◽  
Mass Damper ◽  
Equivalent Mass ◽  
Active Damper

From early times adding auxiliary mass to the main mass has been done to mitigate vibration events. And much research of the structure by adding an equivalent mass using fluid or functional fluid has been done. On the other hand, the research and development of a new damper using rotating inertia mass began in the early 1970s in Japan. The new type damper was termed the “Mechanical Snubber” when it was used for piping and equipment systems in nuclear power plants. Tens of thousands of Mechanical Snubbers are used in Japanese domestic light water reactor and also in foreign countries. As one of the only surviving developers, the author would like to report the development process. This Mechanical Snubber has a large equivalent inertia mass and it accords with the design criteria of high stiffness of seismic method of nuclear power plant. In recent years, in the field of civil engineering and construction, studies using rotating inertia mass or negative stiffness of mechanism have come into favor. These studies are expected to be applied in structure and bridge engineering. This paper describes the historical background of inertia mass dampers, the theory of the inertia mass damper (I.M.D.) applied as a product, and the electromagnetic inertia mass damper (E.I.M.D.) developed as a passive and/or semi-active damper. Some experimental studies using shaking table in the National Center for Research on Earthquake Engineering (NCREE) in Taiwan and theoretical studies are introduced.

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