Seismic Analysis Approach Applied to a Small Size Next Generation Nuclear Reactor

2008 ◽  
Author(s):  
G. Forasassi ◽  
R. Lo Frano
Keyword(s):  
Nuclear Power ◽  
Nuclear Reactor ◽  
Seismic Analysis ◽  
Methodological Approach ◽  
Free Field ◽  
Time History ◽  
Future Generation ◽  
Energy System ◽  
Ground Acceleration ◽  
Input Motion

The aim of the paper is to evaluate the behaviour of a Near Term nuclear energy system example with reference to IRIS (International Reactor Innovative and Safety) project. As it is well known the development of new and future-generation nuclear power plant (Gen IV NPP) is strictly related to the sustainability, safety and reliability as well as to the proliferation resistance. In this paper, the safety aspects related to the effects of a severe earthquake (Safe Shutdown Earthquake) as well as to the induced loads are treated by means the Substructure and Time History Approaches, assuming a free field Peak Ground Acceleration equal to 0.3 g as input motion. The analyses and upgrading of the geometry structures with highest probability of criticality are performed on rather complex and detailed 3D finite element (FE) models. The main goals were: the evaluation of the dynamic characteristics of each considered structure, the verification of the load bearing structures in order to obtain a preliminary assessment of the adopted methodological approach and structural models. The analyses results and dynamic response of internal components (e.g. Nuclear Buildings, etc.) seem to confirm the possibility to upgrade the geometry and the performances of the proposed design choices.

Investigating the Effect of Depth and Impedance of Foundation Rock in Seismic Analysis of Gravity Dams

2014 ◽  
Vol 5 (2) ◽  
pp. 1-18
Author(s):  
Sharad Joshi ◽  
Ishwer Datt Gupta ◽  
Lalitha R. Pattanur ◽  
Pranesh B. Murnal
Keyword(s):  
Half Space ◽  
Seismic Analysis ◽  
Free Field ◽  
Time History ◽  
Gravity Dams ◽  
Ground Acceleration ◽  
Rock Interaction ◽  
Foundation Block ◽  
Substructure Approach ◽  
Foundation Rock

The inhomogenieties of the foundation can be modeled explicitly in standard FEM procedure, however, the results vary significantly with the extent of foundation block modeled and mechanism of applying the input earthquake excitation. The substructure approach provides mathematically exact solution but assumes average properties for the entire foundation as viscoelastic half space. This paper has carried out detailed investigations with varying impedance contrasts and different size of foundation block to show that the results, with suitably deconvoluted free-field ground acceleration time-history applied at the base of foundation block in the FEM approach, are in good agreement with the substructure approach. However, the other variants of the FEM approach may lead to erroneous and overestimated stresses in the dam body. As the foundation of gravity dams can generally be approximated as an equivalent homogeneous half-space, the more accurate and efficient substructure approach can be used to model the dam-foundation rock interaction (SSI) effects in most practical situations.

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.

Analysis and Evaluation of the Liquefaction on Layered Soil

2002 ◽  
Author(s):  
Sang Hoon Lee ◽  
Kwang Hoon Yoo
Keyword(s):  
Nuclear Power ◽  
Time History ◽  
The Other ◽  
Liquefaction Potential ◽  
Analysis And Evaluation ◽  
Seismic Input ◽  
The Us ◽  
Input Motion ◽  
Maximum Shear Strength ◽  
Typical Soil

Liquefaction potential on the specific site of nuclear power plant is analyzed and reviewed. The layered site for this study consists of silt and sand. Based on the limited available soil data, maximum shear strength at critical locations using Seed & Idriss method and computer program SHAKE is calculated, and liquefaction potential is reviewed. As seismic input motion used for the assessment of liquefaction, the artificial time history compatible with the US NRC Regulatory Guide 1.60 is used. Assessment results of the liquefaction are validated by analyzing to the other typical soil foundations which can show the effects on the foundation depth and soil data.

Study on Methods for HCLPF Value of Nonlinear Supports System of Steam Generator

2018 ◽  
Author(s):  
Feng-chun Cai ◽  
Xian-hui Ye ◽  
Qian Huang ◽  
Wenzheng Zhang
Keyword(s):  
Steam Generator ◽  
Nonlinear Model ◽  
Seismic Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Cost Calculation ◽  
Seismic Capacity ◽  
Ground Acceleration ◽  
Reactor Building ◽  
Nonlinear Time History

High confidence of low probability of failure (HCLPF) values of equipment, representing the seismic capacities of the equipment, are the fundamental ingredient in seismic probability safety assessment (SPSA) and seismic margin analyses (SMA). In this paper, two methods for calculating the HCLPF values of equipment were investigated, fragility analysis, and conservative deterministic failure margin (CDFM). These methods are linear methods. Based on these methods, HCLPF value of equipment can be computed conveniently by scaling the results of the existing seismic analysis. For a nonlinear systems, the HCLPF values based on these linear scaling methods are unrealistic. For a complicated nonlinear equipment or structure, a detail nonlinear model was used to derive the seismic capacity. The results by this method are realistic, but cost calculation time. In this paper, a nonlinear model of reactor coolant system coupled reactor building was built. This model includes the steam generator and considers the nonlinear factors of steam generator such as gap in the supports, plasticity of hot leg and cold leg. Forced motion was applied to the base of reactor building. And seismic response of the steam generator was calculated iteratively by scaling the ground motion level step by step. Based on these calculations, a curve of load on the supports VS peak ground acceleration (PGA) can be obtained. Then based on these curves and allowable load of supports of steam generator, which derived from stress analysis on support of steam generator, seismic capacity of the supports of steam generator was determined. Then the HCLPF Value of the supports of steam generator was obtained by this nonlinear time history analysis and was compared with the results based on the CDFM. The two results were different. Therefore, the HCLPF seismic capacity of equipment with nonlinearity, such as gap nonlinearity, should be calculated by nonlinear time history method.

Seismic Analysis of Structures Subjected to Spatially Varying Earthquake Using POD Vectors: Experimental and Analytical Studies

2020 ◽  
Vol 14 (04) ◽  
pp. 2050017
Author(s):  
K. Balamonica ◽  
N. Gopalakrishnan ◽  
A. Ramamohan Rao
Keyword(s):  
Seismic Analysis ◽  
Null Space ◽  
Time History ◽  
Soil Conditions ◽  
Classical Formulation ◽  
Local Soil ◽  
Wave Passage ◽  
Input Motion ◽  
Differential Excitation ◽  
Spatially Varying

Structures, such as bridges, pipelines which are supported at multiple places, will be subjected to differential excitation. A significant change in the correlation of the motions between the two supports is due to the combined effects of wave passage, coherency loss and local soil conditions. In the classical formulation, the response is divided into quasi-static and dynamic components and the latter is usually evaluated by time history methods or modal analysis for a linear system. In this work, the feasibility of Proper Orthogonal Decomposition (POD) vectors as a replacement for the conventional eigenvectors has been discussed. The performance of POD modes has been assessed for the uncoupled system, system having closely spaced modes. The null space vectors of the POD modes generated from the response of the structure subjected to correlated input motion were able to predict the responses of the structures subjected to spatially varying input motions. The efficiency of using the POD vectors has also been verified with the help of an experiment conducted on a steel control and safety rod drive mechanism (CSRDM) which is an example of multi-supported and differentially excited structure.

scholarly journals Performance-based seismic assessment of vulnerability of dam using time history analysis

2018 ◽  
Vol 149 ◽  
pp. 02035
Author(s):  
Oumnia Elmrabet ◽  
Hasnae Boubel ◽  
El Mehdi Echebba ◽  
Mohamed Rougui ◽  
Ouadia Mouhat
Keyword(s):  
Soil Structure ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Time History ◽  
Time History Analysis ◽  
Seismic Assessment ◽  
Assessment Procedure ◽  
Ground Acceleration ◽  
History Analysis ◽  
Al Hoceima

The current performance-based seismic assessment procedure can be computationally intensive as it requires many time history analyses (THA) each requiring time intensive post-processing of results. Time history analysis is a part of structural analysis and is the calculation of the response of a structure to any earthquake. It is one of the main processes of structural design in regions where earthquakes are prevalent. The objective of this study is to evaluate the seismic performance of embankment dam located on the Oued RHISS in the Province of AL HOCEIMA using the THA method. To monitor structural behavior, the seismic vulnerability of structure is evaluated under real earthquake records with considering the soil-structure-fluide interaction. In this study, a simple assistant program is developed for implementing earthquake analyses of structure with ANSYS, ground acceleration–time history data are used for seismic analysis and dynamic numerical simulations were conducted to study and identify the total response of the soil-structure system.

Seismic Analysis for the Subsea Pipeline System

2010 ◽  
Author(s):  
Rosman B. Arifin ◽  
Wan M. Shafrizal B. Wan M. Yusof ◽  
Pengfei Zhao ◽  
Yong Bai
Keyword(s):  
Seismic Wave ◽  
Seismic Analysis ◽  
Ground Deformation ◽  
Time History ◽  
Metal Loss ◽  
Pipeline System ◽  
Wave Impact ◽  
Ground Acceleration ◽  
Permanent Ground Deformation ◽  
The Impact

Seismic activity in Malaysia is very low as earthquakes are infrequent in this region. The strongest measured earthquake magnitude record in this region since 1978 was 4, which had a very low impact on the integrity of pipelines system in Malaysia. Although this is the case, there exists seismic events in the neighbouring regions and such events may impact the operability, stability and safety of Malaysia submarine pipeline systems. Based on this, a pipeline integrity analysis has been carried out to check the pipeline integrity under the seismic influence. The purpose of the analysis includes: • To calculate earthquake response for three PCSB PMO main export pipelines — for each pipeline both buried and unburied conditions will be taken into account. • To understand the characteristics of buried and unburied pipelines under strong earthquakes affecting Malaysia waters. • To determine the peak ground acceleration (PGA) the pipelines can withstand. • To determine the largest permanent ground deformation (PGD) the pipeline can withstand. • To estimate the impact of the metal loss on the pipeline integrity. • To assist PETRONAS to prepare for such severe earthquakes. Two typical methods have been employed to make the analysis: • Time history method is used to calculate both buried and unburied pipeline response. Two typical seismic wave records have been used in the analysis, which will give a better estimation of the pipeline response under the seismic wave impact. • Soil-pipe element method is used to simulate the behavior between the soil and buried pipeline system. Based on choosing the suitable experimental equations, this method can simulate the soil behaviour accurately. This paper discusses results of the seismic analysis. Based on the analysis results, the pipeline system will be safe under the seismic wave impact. More attention should be given to fault hazard, as the pipeline system will been failed under the fault impact. Finally, the metal loss will be taken into consideration, for the pipeline stress will be much higher due to great metal loss. All those analysis results will be further utilised to estimate the pipeline response in the case of the earthquake.

scholarly journals Influence of irradiation on the dynamics of changes in the mechanical properties of the nuclear reactor vessel

2018 ◽  
Vol 226 ◽  
pp. 01024
Author(s):  
Yulia S. Bakhracheva
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Nuclear Reactor ◽  
Automatic Monitoring ◽  
Energy System ◽  
Reactor Vessel ◽  
Reactor Steels ◽  
Irradiation Level ◽  
Emergency Systems

Nuclear power plants are important generating units of the energy system worldwide. In the normal mode, nuclear power plants are absolutely safe, but emergency systems with radiation emissions have a devastating impact on the environment and public health. Despite the introduction of technologies and automatic monitoring systems, the threat of a potentially dangerous situation remains. The reactor vessel is the main object of activities to ensure the safety of nuclear power plants. One of the problems of ensuring the safety of nuclear power plant reactor vessels is the prediction of the level of crack resistance of reactor steels. The paper shows the possibility of estimating the neutron irradiation level on the nature of the temperature dependence of KIC. The prediction of the influence of radiation damage on the fracture toughness of the reactor steel can be obtained on the basis of the results of tests of small cylindrical samples with annular notches.

Lateral Structure Interaction With Seismic Waves

1971 ◽  
Vol 38 (1) ◽  
pp. 125-134 ◽  
Author(s):  
R. J. Scavuzzo ◽  
J. L. Bailey ◽  
D. D. Raftopoulos
Keyword(s):  
Half Space ◽  
San Francisco ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Waves ◽  
Structural Characteristics ◽  
Free Field ◽  
Elastic Half Space ◽  
Inertia Force ◽  
Ground Acceleration

The interaction of lateral structural inertia forces with horizontal seismic motion is formulated in terms of an integral equation of the Volterra type. By means of normal mode theory the inertia force at the base of the structure is expressed as a function of the foundation motion. After the motion of the two-dimensional elastic half space resulting from a uniform horizontal foundation force varying arbitrarily with time over a specified interval on the boundary of the half space has been determined, the interaction equation is derived. Numerical studies for two free-field acceleration inputs are made for different ground stiffnesses and structural characteristics. The first of these free-field inputs is a ramp sine function and the second is the east-west ground acceleration recorded at Golden Gate Park during the 1957 San Francisco earthquake. The interaction effects for structures similar to nuclear power plants prove to be significant.

scholarly journals Studies on Optimal Strategy to Adopt Nuclear Power Plants into Saudi Arabian Energy System Using MESSAGE Tool

2021 ◽  
Vol 2021 ◽  
pp. 1-26
Author(s):  
Shadwan M. M. Esmail ◽  
Jae Hak Cheong
Keyword(s):  
Saudi Arabia ◽  
Optimal Strategy ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Nuclear Reactor ◽  
Energy System ◽  
Strategic Options ◽  
Electricity Shortage

An optimal long-term electric power strategy for Saudi Arabia to adopt nuclear power was evaluated using the MESSAGE tool. Saudi Arabia is predicted to experience an electricity shortage by 2025 with the present energy system. This electricity shortage could be postponed until 2035 by rehabilitating the existing power plants. The MESSAGE model predicts that adopting a combination of renewable (i.e., solar and wind), advanced traditional power (i.e., gas turbine, steam, and combined cycle), and nuclear technologies is the most competitive future strategy to supply 43.7%, 41.6%, and 3.8%, respectively, of Saudi Arabia’s electricity needs by 2050. This paper proposes an optimal strategy for adopting nuclear power. The nuclear capacity of three scenarios was evaluated: a single APR-1400 nuclear reactor, a single SMART-100 nuclear reactor, and a combination of these two reactors. The results of this study indicate that the highest nuclear capacity was achieved by the combination of the APR-1400 and SMART-100 reactors followed by the single APR-1400 reactor and then the single SMART-100 reactor. However, the single G4ECONS nuclear reactor shows a higher capacity than the single APR-1400 reactor in other evaluated scenarios. The combined reactor strategy may be the most feasible option if the capital cost of a first-of-a-kind SMART-100 reactor is reduced by 62.3%. The cost reductions result from including factors like the time required to build the nuclear power plants in the MESSAGE tool calculation. Also, CO2 taxation will increase nuclear power’s feasibility in the Saudi Arabian energy system. However, the share of renewable energy is predicted to be more affected by the taxation of CO2. In this study, the proposed approach can provide more flexible strategic options for countries embarking on nuclear energy. These flexible strategic options can optimize their national energy mix for long-term planning.

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