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.

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.

Periodic Materials-Based 3D Seismic Base Isolators for Nuclear Power Plants

2014 ◽  
Author(s):  
Y. Yan ◽  
A. Laskar ◽  
Z. Cheng ◽  
F. Menq ◽  
Y. Tang ◽  
...  
Keyword(s):  
Earthquake Engineering ◽  
Structural Damage ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Waves ◽  
Natural Frequencies ◽  
Field Tests ◽  
Band Gaps ◽  
Solid State Physics ◽  
Periodic Materials

The concept of periodic materials, based on solid state physics theory, is applied to earthquake engineering. The periodic material is a material which possesses distinct characteristics that do not allow waves with certain frequencies to be transmitted through; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. In designing a periodic foundation, the first step is to match band gaps of the periodic foundation with the natural frequencies of the superstructure. This is an iterative process. Starting with a design of the periodic foundation, the band gaps are identified by performing finite element analyses using ABAQUS. This design process is repeated until the band gaps match natural frequencies of the superstructure, and the field tests of a scaled specimen are conducted to validate the design. This is an on-going research project. Presented in this paper are the preliminary results, which show that the three dimensional periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitations.

Efficient Intensity Measures for Probabilistic Seismic Response Analysis of Anchored Above-Ground Liquid Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Analysis ◽  
Time History ◽  
Response Analysis ◽  
Storage Tanks ◽  
Intensity Measures ◽  
Study Results

Liquid storage tanks are vital lifeline structures and have been widely used in industries and nuclear power plants. In performance-based earthquake engineering, the assessment of probabilistic seismic risk of structural components at a site is significantly affected by the choice of ground motion intensity measures (IMs). However, at present there is no specific widely accepted procedure to evaluate the efficiency of IMs used in assessing the seismic performance of steel storage tanks. The study presented herein concerns the probabilistic seismic analysis of anchored above-ground steel storage tanks subjected to several sets of ground motion records. The engineering demand parameters for the analysis are the compressive meridional stress in the tank wall and the sloshing wave height of the liquid free surface. The efficiency and sufficiency of each alternative IM are quantified by results of time history analyses for the structural response and a proper regression analysis. According to the comparative study results, this paper proposes the most efficient and sufficient IMs with respect to the above demand parameters for a portfolio of anchored steel storage tanks.

Statistical Analysis of Seismic Effects of Low Seismic Class Equipment Based on Damage Data of Nuclear Power Plants

2014 ◽  
Author(s):  
Ryo Morita ◽  
Fumio Inada ◽  
Yasuki Ohtori ◽  
Mitsuhide Nanpo ◽  
Koji Naradate ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Lower Class ◽  
Shaking Table ◽  
Loss Of Function ◽  
Shaking Table Tests ◽  
Seismic Effects ◽  
Class B ◽  
Damage Data ◽  
Large Earthquakes

Structural strengths of the piping and components in NPPs have been designed with seismic margin. They are classified seismically S, B and C class in terms of the influence rate to nuclear safety. For the highest seismic class (Class S) equipment, it is clarified that they have enough seismic margins against design seismic conditions by shaking table tests or numerical simulations. However, for the lower seismic class (Class B and C) equipment, their seismic margins have not been clarified quantitatively. In this paper, in order to evaluate seismic robustness of the lower seismic class equipment with no clarification of seismic margin, seismic influences of the lower seismic class equipment in NPPs damaged by actual large earthquakes have been surveyed and sorted as a database, and the integrity of the lower class equipment have been discussed. Seismic effects on 24 plants damaged by the recent large 6-earthquakes are surveyed, sorted as a database, and investigated. As a result, a total of 29 cases of function deterioration or loss were observed. Considering the total number of components and piping, the frequency of those cases in class B and C components and piping was low. And also, as it is found there are a few cases of degradation or loss of function in the equipment installed on the bedrock or in the buildings.

Dynamic Processes in Vacuum Contact Devices of Robots for Vertical Motion in the Water Environment

2019 ◽  
Vol 20 (7) ◽  
pp. 417-421
Author(s):  
V. G. Gradetsky ◽  
M. M. Knyazkov ◽  
E. A. Semenov ◽  
A. N. Sukhanov
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Water Environment ◽  
Experimental Studies ◽  
Vertical Motion ◽  
Contact Device ◽  
Dynamic Processes ◽  
Simplified Models ◽  
Contact Devices ◽  
Air Ejector

The results of experimental investigation intended to improve movement conditions for pneumatic robots on vertical surfaces under water are discussed. Features of the movement of vacuum contact devices for the simulation of mathematical model of the vacuum contact device with surfaces under water are presented. The experimental studies made it possible to obtain additional data on the dynamics of attachment, to obtain transient processes for air-water flow through ejector and to correct the results obtained earlier. For the purpose of analytical study of dynamic processes occurring in the system of vacuum contact devices, and taking into account the complexity of the description of nonlinearities, linearized simplified models of the system "air ejector — contact device — water environment" were developed. Vacuum contact devices are designed to provide guaranteed contact with vertical surfaces, plane slopes or horizontal surfaces on which the underwater robot performs its movement, carrying out the prescribed technological tasks, for example, in dry wells of nuclear power plants, on the surfaces of ship hulls, on the surfaces of underwater structures. The models took into account the forces of adhesion to the surfaces under water — the forces from the pressure drop, the friction force, the contact and vacuum interaction, the elasticity of suction caps. As a result of the solution of the model problem, the values of mechanical parameters, as well as the values of vacuum and flow in the cavity of variable volume as functions of changing the gap between the end of the corrugated membrane and the surfaces are obtained explicitly. As a result of the study of dynamic processes occurring in simplified models of vacuum contact devices "air ejector — contact surface — water environment", the transient characteristics of the change in the operating forces and pressures over time, as well as the dependence of the normal and tangential components of the forces on the depth of immersion in water were obtained. The variants of the designs of vacuum contact devices with surfaces in the water environment are investigated, and the modernization of the laboratory test bench for testing vacuum contact devices under water is carried out.

Seismic Test Results of Air-Operated Valve Actuators for Nuclear Power Plants (Air-Operated Globe Valve (Cylinder Type))

2019 ◽  
Author(s):  
Ryo Kubota ◽  
Yoshitaka Tsutsumi ◽  
Yoshinao Matsubara ◽  
Shigeki Suzuki ◽  
Shin Kumagai
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Shaking Table ◽  
Test Results ◽  
Active Components ◽  
Seismic Testing ◽  
Globe Valve

Abstract It is believed that air-operated globe valves are able to operate during and after earthquakes, leading to maximum accelerations beyond the existing allowable acceleration for nuclear power plants in Japan (6 × 9.8 m/s2). In this work, this assumption is verified using a resonance shaking table for seismic testing at acceleration levels of 20 × 9.8 m/s2 (see Ref. [1]). Results show that the active components used in existing air-operated globe valve designs remain operable at 22 × 9.8 m/s2 (horizontal (X and Y) and vertical (Z) directions).

Seismic Test Results of the Main Steam Isolation Valve for Japanese Boiling Water Reactor Nuclear Power Plants

2020 ◽  
Author(s):  
Hideaki Itabashi ◽  
Yoshitaka Tsutsumi ◽  
Koji Nishino ◽  
Shin Kumagai
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Shaking Table ◽  
Boiling Water ◽  
Boiling Water Reactor ◽  
Central Research ◽  
Water Reactor ◽  
Seismic Tests ◽  
Main Steam

Abstract The functional requirements of Main Steam Isolation Valves (MSIVs) provided in the Boiling Water Reactor (BWR) nuclear power plants in Japan have been previously evaluated via seismic tests and so forth. However, since the response acceleration has increased in line with a recent reassessment of standard earthquake ground motions, it is necessary to evaluate seismic operability with respect to high acceleration. In addition, from the viewpoint of equipment fragility in seismic PRA, it is necessary to determine practical seismic operability limits. We used a resonant shaking table in the Central Research Institute of the Electric Power Industry (CRIEPI), which is capable of seismic tests at acceleration levels previously unachievable, and in seismic tests carried out on an MSIV, we obtained results confirming that validated seismic operability was possible even at response accelerations as high as 15 × 9.8 m/s2. The seismic operability results obtained for this MSIV will be applied to a fragility analysis of seismic PRA.

Experimental Studies of Radiation-Protective Properties of a Modified Titanium Hydride

2022 ◽  
Vol 1049 ◽  
pp. 174-179
Author(s):  
A.A. Karnauhov ◽  
R.N. Yastrebinskii
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Titanium Hydride ◽  
Nuclear Power ◽  
Power Plants ◽  
High Efficiency ◽  
Experimental Studies ◽  
Point Sources ◽  
Relaxation Length ◽  
Protective Properties

The results of experimental studies of the protective properties of titanium hydride with respect to neutron and gamma radiation in order to determine the optimal conditions for their use in the composition of the structural radiation protection of the nuclear reactor are presented. The weakening of the basic functionals in the thickness of protection, including the density of fast, intermediate and thermal neutrons, and the dose rate of gamma radiation is established. The functions of weakening the density of neutron flow and the dose rate of gamma radiation are measured in the conditions of "barrier" geometry. Determination of the protective properties of the structure was carried out when the modified titanium hydride fraction was placed in aluminum containers with a filling coefficient of a volume of container 0.63. The relaxation lengths for all neutron groups are close and on average are 9.8 cm. The functions of weakening the dose rate of gamma radiation of point sources Cs-137 and Co-60 are exponential. The weakening of radiation occurs with a constant relaxation length. For energy 0.661 MeV, the relaxation length is 7.1 cm, for energy 1.25 MeV, the relaxation length is equal to 10.1 cm. On the basis of the experimental studies, the high efficiency of the modified fraction of titanium hydride was confirmed during its use in protecting nuclear power plants.

A Short Note for Dr. Shibata's Review in 1975

2006 ◽  
Vol 1 (2) ◽  
pp. 189-189
Author(s):  
Kohei Suzuki ◽  
Keyword(s):  
Seismic Design ◽  
Earthquake Engineering ◽  
Nuclear Power ◽  
Power Plants ◽  
Short Note ◽  
Pressure Vessels ◽  
Professor Emeritus ◽  
Industrial Facilities ◽  
Kobe Earthquake ◽  
And Control

Dr. Heki Shibata, Professor Emeritus of the University of Tokyo, who authored this paper, is a pioneer in earthquake engineering in Japan and the leading expert in mechanical engineering and seismic design of involving pressure vessels and piping equipment of nuclear power plants and high-pressure gas plants. In this paper, he classifies and analyzes mode failures and failure mechanisms in a variety of equipment based on his experience in surveying the damage to industrial facilities caused by the 1964 Niigata Earthquake and the 1971 San Fernando Earthquake. He proposes introducing the "factor of importance" based on potential of danger in seismic design, developing basic seismic design calculating the maximum response of a structure using seismic coefficients including those defined using this factor of importance. This idea has been effectively implemented as the basis for seismic design of structures and equipment to this day, and its historical value has been proven. He points out the importance of the reliability of seismic design and the safe design of instrumentation and control in seismic design. Dr. Shibata emphasizes the importance of learning the lessons presented by the damage experienced in earthquakes, the 1995 Kobe Earthquake - yet another example of his invaluable foresight.

Seismic Hazard and Damages—Avoiding Disaster Through Simulation, Experiment, and Experience

1999 ◽  
Vol 121 (1) ◽  
pp. 30-36 ◽  
Author(s):  
H. Shibata
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Mechanical Engineering ◽  
Design Procedure ◽  
Shaking Table ◽  
Test Facility ◽  
Design Stage ◽  
Engineering Structures ◽  
Aseismic Design ◽  
Piping Systems

This paper deals with the role of proving tests and a large shaking test facility for equipment and piping systems in conjunction with the development of aseismic design in the field of mechanical engineering, especially for nuclear power plants in Japan. To avoid seismic disaster and damage of equipment and piping systems as well as liquid storages, we had to differentiate the seismic design procedure in mechanical engineering from that for building and civil engineering structures. For this process, the dynamic analysis in this field is more significant than for other fields. The author has been trying to develop aseismic design since the design stage of the first nuclear power plant in 1958 based on his experience as a specialist of mechanical vibration. In the early 1970s, shaking tables were developed for this purpose in Japan. The largest one in Japan is a 1000-ton 2-D table. After the 1995 Kobe earthquake, we have been developing a new 1200-ton 3-D shaking table. In the paper, the author discusses the necessity of such a facility and presents a new concept of a numerical shaking table.

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