Development of Seismic Design Method for Free Standing Rack

For high earthquake resistance and ease of installation, free standing racks which are not anchored to the pool floor or walls has been adopted in many countries. Under the earthquake, the response of the free standing rack is highly nonlinear and involves a complex combination of motions (sliding, rocking, twisting, and turning) and impacts between the fuel assemblies and the fuel cell walls, rack-to-rack, and the pit floor and the rack pedestals. To obtain an accurate simulation of the free standing rack, the seismic analysis requires careful considerations of these complex phenomena (sliding, rocking, twisting, and turning), fluid coupling effects and frictional effects. The important evaluation items while applying the free standing rack to the actual nuclear plants are maximum sliding displacement of the rack, maximum rocking displacement and maximum leg load under earthquake. When the sliding displacement increases, the rack may collide against the spent fuel pool wall. In addition, the free standing rack should not exhibit tilt sufficient to cause to the rack to overturn. The vibration tests were conducted in order to predict the rack behavior under earthquake, and the analysis method was validated by comparison to tests results. Furthermore, we developed the seismic design method to obtain the margin of safety for free standing rack.

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Seismic Design of Free Standing Racks in Japanese Nuclear Power Plants

Volume 8: Seismic Engineering ◽

10.1115/pvp2017-65740 ◽

2017 ◽

Author(s):

Yu Takaki ◽

Katsuhiko Taniguchi ◽

Junichi Kishimoto ◽

Akihisa Iwasaki ◽

Yoshitsugu Nekomoto ◽

...

Keyword(s):

Seismic Design ◽

Nuclear Power ◽

Power Plants ◽

Design Method ◽

Seismic Resistance ◽

Spent Fuel ◽

Analysis Model ◽

Free Standing ◽

Scale Free ◽

Seismic Design Method

The free standing racks are spent fuel storage racks with self-sustained structure without fixation to the pit floor or pit walls. If a free standing rack receives a force to move it due to an earthquake, the force acting on each member of the rack is reduced in compared to the floor-anchored racks owing to sliding of the free standing rack. Now it is planned to exchange the existing floor-anchored racks with the free standing racks to secure higher seismic resistance. In previous studies, efforts were made to establish a behavior analysis model that allows for evaluation of sliding and rocking behaviors of free standing racks and to make out a seismic design method based on an evaluation technique to evaluate, in a conservative manner, vibration test results of full-scale free standing racks. The free standing racks which consist of connected eight racks are designed with this seismic design method. It was confirmed that the free standing racks have enough seismic resistance by performing evaluation using the basic seismic motion and making an analysis on beyond the design event.

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Evaluation of the Sliding Behavior of the Rack Using CAV Concept

ASME 2011 Pressure Vessels and Piping Conference: Volume 8 ◽

10.1115/pvp2011-57933 ◽

2011 ◽

Author(s):

Akihisa Iwasaki ◽

Yoshitsugu Nekomoto ◽

Hideyuki Morita ◽

Shingo Nishida ◽

Mitsuru Nagaya ◽

...

Keyword(s):

Simulation Analysis ◽

Seismic Analysis ◽

Time History ◽

Spent Fuel ◽

Free Standing ◽

Pass Filter ◽

Low Pass Filter ◽

Cumulative Absolute Velocity ◽

Low Pass ◽

Spent Fuel Pool

The spent fuel taken out of a nuclear plant reactor is temporarily stored in spent fuel racks. This fuel will often have to be stored in the long periods before it can be moved to a reprocessing facility. Therefore, the spent fuel rack must have a large capacity with a high tolerance against big seismic loads. So, the free standing rack is developed as the optimal equipment meeting these requirements. The free standing fuel rack is installed on the floor in the spent fuel pool and it can have the simple structure, as it needs no supports on the floor or the wall of the spent fuel pool. The free standing spent fuel rack structure actively incorporates the effects of the friction force generated on the spent fuel pool floor, and the fluid effect. So, seismic analysis is performed by nonlinear dynamic time history analysis. In this study, we applied CAV concept (CAV: Cumulative Absolute Velocity) to evaluate of nonlinear rack response. And it was confirmed that the CAV concept using the low-pass filter is useful to evaluate the sliding and rocking behavior of the rack by simulation analysis.

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Experimental and Analysis Study of Free Standing Rack Under Seismic Excitation

Volume 2: Plant Systems, Structures, and Components; Safety and Security; Next Generation Systems; Heat Exchangers and Cooling Systems ◽

10.1115/icone20-power2012-55240 ◽

2012 ◽

Author(s):

Katsuhiko Taniguchi ◽

Daisaku Okuno ◽

Akihisa Iwasaki ◽

Yoshitsugu Nekomoto ◽

Toshihiro Matsuoka

Keyword(s):

Evaluation Method ◽

Seismic Analysis ◽

Nonlinear Dynamic Analysis ◽

Full Scale ◽

Free Standing ◽

Highly Nonlinear ◽

Dry Conditions ◽

Scale Test ◽

Complex Phenomena ◽

Test Result

For high earthquake resistance and ease of installation, free standing racks which are not anchored to the pool floor or walls has been adopted in many countries. Under the earthquake, the response of the free standing rack is highly nonlinear and involves a complex combination of motions (sliding, rocking, twisting, and turning) and impacts between the fuel assemblies and the fuel cell walls, rack-to-rack, and the pit floor and rack pedestals. To obtain an accurate simulation of the free standing rack, the seismic analysis requires careful considerations of these complex phenomena (sliding, rocking, twisting, and turning), fluid coupling effects and frictional effects. We carried out seismic experiments on the full-scale rack model in water and dry conditions to obtain the fundamental data about free standing rack (sliding, rocking and turning motions). We have developed the nonlinear dynamic analysis method to predict seismic response for the free standing rack utilizing the full-scale test result and verified the analysis evaluation method of the rack by comparison of test result.

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Seismic Design Method for Hybrid Viaduct in Japanese Railways

IABSE Congress Report ◽

10.2749/222137900796298751 ◽

2000 ◽

Vol 16 (20) ◽

pp. 338-346

Author(s):

Kiyomitsu MURATA ◽

Masato YAMADA ◽

Tomohiro TAKAYAMA ◽

Masanori KINOSHITA

Keyword(s):

Seismic Design ◽

Design Method ◽

Seismic Design Method

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Influence of Gap Size on Added Mass for Spent Fuel Storage Rack

Volume 2: Plant Systems, Structures, Components, and Materials; Risk Assessments and Management ◽

10.1115/icone26-82595 ◽

2018 ◽

Cited By ~ 1

Author(s):

Daogang Lu ◽

Yu Liu ◽

Shu Zheng

Keyword(s):

Vibration Frequency ◽

Input Parameter ◽

Added Mass ◽

Water Tank ◽

Spent Fuel ◽

Free Standing ◽

Fluid Force ◽

Spent Fuel Storage ◽

Fuel Storage ◽

Spent Fuel Pool

Free standing spent fuel storage racks are submerged in water contained with spent fuel pool. During a postulated earthquake, the water surrounding the racks is accelerated and the so-called fluid-structure interaction (FSI) is significantly induced between water, racks and the pool walls[1]. The added mass is an important input parameter for the dynamic structural analysis of the spent fuel storage rack under earthquake[2]. The spent fuel storage rack is different even for the same vendors. Some rack are designed as the honeycomb construction, others are designed as the end-tube-connection construction. Therefore, the added mass for those racks have to be measured for the new rack’s design. More importantly, the added mass is influenced by the layout of the rack in the spent fuel pool. In this paper, an experiment is carried out to measure the added mass by free vibration test. The measured fluid force of the rack is analyzed by Fourier analysis to derive its vibration frequency. The added mass is then evaluated by the vibration frequency in the air and water. Moreover, a two dimensional CFD model of the spent fuel rack immersed in the water tank is built. The fluid force is obtained by a transient analysis with the help of dynamics mesh method.

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Research Situation on the Performance-Based Seismic Design Method for Reinforced Concrete Structure

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.163-167.1757 ◽

2010 ◽

Vol 163-167 ◽

pp. 1757-1761

Author(s):

Yong Le Qi ◽

Xiao Lei Han ◽

Xue Ping Peng ◽

Yu Zhou ◽

Sheng Yi Lin

Keyword(s):

Reinforced Concrete ◽

Seismic Design ◽

Design Method ◽

Concrete Structures ◽

Reinforced Concrete Structures ◽

Seismic Evaluation ◽

Seismic Codes ◽

Performance Based Seismic Design ◽

Capacity Calculation ◽

Seismic Design Method

Various analytical approaches to performance-based seismic design are in development. Based on the current Chinese seismic codes，elastic capacity calculation under frequent earthquake and ductile details of seismic design shall be performed for whether seismic design of new buildings or seismic evaluation of existing buildings to satisfy the seismic fortification criterion “no damage under frequent earthquake, repairable under fortification earthquake, no collapse under severe earthquake”. However, for some special buildings which dissatisfy with the requirements of current building codes, elastic capacity calculation under frequent earthquake is obviously not enough. In this paper, the advanced performance-based seismic theory is introduced to solve the problems of seismic evaluation and strengthening for existing reinforced concrete structures, in which story drift ratio and deformation of components are used as performance targets. By combining the features of Chinese seismic codes, a set of performance-based seismic design method is established for reinforced concrete structures. Different calculation methods relevant to different seismic fortification criterions are adopted in the proposed method, which solve the problems of seismic evaluation for reinforced concrete structures.

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