Seismic Analysis of an Intake Tunnel of Different Tunnellining Programs for a Nuclear Power Plant

2013 ◽  
Vol 353-356 ◽  
pp. 2084-2091
Author(s):  
Gui Zhen Wang ◽  
Ying Min Li ◽  
Zhi Peng Lu
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Seismic Analysis ◽  
Time History ◽  
Internal Force ◽  
Response Analysis ◽  
Analysis And Design ◽  
Static And Dynamic Analysis ◽  
History Analysis

Developing an analysis program and simulating the radiation damping effect in the infinite foundation and inputs ground motion rationally. The static and dynamic analysis of an intake tunnel for a nuclear power plant is performed with ANSYS based on some 2-D finite element models considering of structure-foundation interaction by Time-History Analysis. Aiming at different programs of two linings in tunnel, the stress and internal force distribution of the tunnel , the wall rocks and the lining is researched and analyzed, and the diagram of stress and internal force is drawn. The regularity obtained can provide the basis for the seismic response analysis and design of tunnels.

Seismic Analysis of Intake Tunnel for Nuclear Power Plant

2011 ◽  
Vol 243-249 ◽  
pp. 3513-3517
Author(s):  
Jie Zhao ◽  
Yang Zheng ◽  
Gui Xuan Wang
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Time Domain ◽  
Nuclear Power ◽  
Seismic Analysis ◽  
Time Domain Analysis ◽  
Internal Force ◽  
Response Analysis ◽  
Plant Structure ◽  
Seismic Response Analysis

Aiming at the nuclear power plant structure and adopting time domain analysis approach, the seismic analysis of an intake tunnel for nuclear power plant is performed with FLAC3D in this paper. Contraposing the characters of the field rock of the nuclear plant, the internal force distribution of the tunnel under different wall rocks is researched and analysed, and the envelope diagram of inner force in the lining of the tunnel is drawn. The obtained law can provide the basis for the seismic response analysis of tunnels.

Assess of the Nuclear Power Plant Structures Residual Life and Earthquake Resistance

2013 ◽  
Vol 284-287 ◽  
pp. 1247-1250 ◽  
Author(s):  
Vlastislav Salajka ◽  
Petr Hradil ◽  
Jiri Kala
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Analysis ◽  
Residual Life ◽  
Actual State ◽  
Response Analysis ◽  
Seismic Load ◽  
General View

The paper deals with the seismic analysis of safety related structures of an operating nuclear power plant. At present time the nuclear power plants of VVER-400/213 type operate for over thirty years and there are arising requirements to verify the actual state of structures in order to assess their residual life in general. A sophisticated computation model has been developed for the seismic structural analysis using the ANSYS program package. The model involves the complex of all constrained structures of two main production blocks with equipment. In order to get a general view at the seismic load effects, seismic response analysis has been performed using direct integration of equations of motion in 25 sec interval at 0.01 sec step with excitation described by accelerograms. Combinations of dead loads and seismic loads have been considered in the stress assessment of the structures. The results of the performed analyses form a base for residual life prediction of selected structures

Seismic Analysis and Design Upgrade of Condensate Storage Tanks

2016 ◽  
Author(s):  
Daniel Moreno ◽  
John O’Sullivan ◽  
Tsiming Tseng
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Seismic Analysis ◽  
Seismic Loads ◽  
Storage Tanks ◽  
Analysis And Design ◽  
Pull Out ◽  
Design Basis ◽  
Regulatory Commission

Following the accident at the Fukushima Daiichi Nuclear Power Plant resulting from the March 11, 2011 Great Tohoku Earthquake and subsequent tsunami, there was a general concern regarding the beyond design basis capability of existing nuclear power plants. The Condensate Storage Tanks (CST) in the nuclear power plant were originally designed to withstand an earthquake with a peak ground acceleration (PGA) of 0.3g. The government regulatory commission increased the required PGA to 0.4g, therefore, an upgrade of the design basis for the CSTs was required. Due to the vintage of the existing nuclear power plant, the United States Nuclear Regulatory Commission (USNRC) Unresolved Safety Issue (USI) A-46 methodology may be used for seismic upgrade work of the mechanical and electrical equipment. The Condensate Storage Tanks (CST) belong to the mechanical and electric equipment and therefore were required to have seismic upgrade work because of significant deficiencies that were found in the anchorage of the tanks to the concrete foundation. A seismic analysis and design upgrade of the Condensate Storage Tanks (CST) was performed to resolve exceedances for base shear, overturning moment and sloshing due to recently updated seismic loads. A detailed analysis of the CST showed that the as-built anchor chair detail did not provide sufficient margin for the Beyond Design Basis Earthquake Event (BDBEE). The as-built anchor chair detail did not provide the required strength to transfer the shear and pull-out loads from the tank shell to the concrete foundation, i.e. no clear load path was provided for the updated seismic loads. Therefore, as a result of the inadequate anchorage, the main issues to resolve in the CST were tank sliding, shell buckling and sloshing due to earthquake loading. The principal challenges encountered during the analysis, design and construction stages were (1) not allowing to loosen the double nut configuration attaching the anchor bolt to the existing anchor chair, and therefore allowing to (2) remove or replace only a few components of the as-built anchor chair, and (3) the retrofit design had to be implemented while tanks were operable, i.e. filled with fluid. An additional challenge faced during the design of the new anchor chair components was the limit in anchor chair height imposed by the numerous interferences in the CST such as nozzles, reinforcing plates and existing welds. A mitigation strategy is analyzed, designed and successfully implemented for retrofitting the ninety-six anchor chairs and allowing for full development of the anchor bolt shear and pull-out strength.

Research on Earthquake Acceleration Alarm of Nuclear Power Plant

2021 ◽  
Author(s):  
Li Liang ◽  
Pan Rong ◽  
Ren Guopeng ◽  
Zhu Xiuyun
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
False Alarm ◽  
Ground Motion ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Time History ◽  
Seismic Acceleration ◽  
Trigger Signal

Abstract Almost all nuclear power plants in the world are equipped with seismic instrument system, especially the third generation nuclear power plants in China. When the ground motion measured by four time history accelerometers of containment foundation exceeds the preset threshold, the automatic shutdown trigger signal will be generated. However, from the seismic acceleration characteristics, isolated and prominent single high frequency will be generated the acceleration peak, which has no decisive effect on the seismic response, may cause false alarm, which has a certain impact on the smooth operation of nuclear power plant. According to the principle of three elements of ground motion, this paper puts forward a method that first selects the filtering frequency band which accords with the structural characteristics of nuclear power plants, then synthesizes the three axial acceleration time history, and finally selects the appropriate acceleration peak value for threshold alarm. The results show that the seismic acceleration results obtained by this method can well represent the actual magnitude of acceleration, and can solve the problem of false alarm due to the randomness of single seismic wave, and can be used for automatic reactor shutdown trigger signal of seismic acceleration.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 2 — Application of CCFS Method to the Multiply Supported Systems

2014 ◽  
Author(s):  
Koichi Tai ◽  
Keisuke Sasajima ◽  
Shunsuke Fukushima ◽  
Noriyuki Takamura ◽  
Shigenobu Onishi
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Time History ◽  
Piping System ◽  
History Analysis ◽  
Piping Systems ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Paper is focused on the seismic evaluation method of the multiply supported systems, as the one of the design methodology adopted in the equipment and piping system of the seismic isolated nuclear power plant in Japan. Many of the piping systems are multiply supported over different floor levels in the reactor building, and some of the piping systems are carried over to the adjacent building. Although Independent Support Motion (ISM) method has been widely applied in such a multiply supported seismic design of nuclear power plant, it is noted that the shortcoming of ignoring correlations between each excitations is frequently misleaded to the over-estimated design. Application of Cross-oscillator, Cross-Floor response Spectrum (CCFS) method, proposed by A. Asfura and A. D. Kiureghian[1] shall be considered to be the excellent solution to the problems as mentioned above. So, we have introduced the algorithm of CCFS method to the FEM program. The seismic responses of the benchmark model of multiply supported piping system are evaluated under various combination methods of ISM and CCFS, comparing to the exact solutions of Time History analysis method. As the result, it is demonstrated that the CCFS method shows excellent agreement to the responses of Time History analysis, and the CCFS method shall be one of the effective and practical design method of multiply supported systems.

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