scholarly journals Handbook of nuclear power plant seismic fragilities, Seismic Safety Margins Research Program

1983 ◽  
Author(s):  
L.E. Cover ◽  
M.P. Bohn ◽  
R.D. Campbell ◽  
D.A. Wesley
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Research Program ◽  
Nuclear Power ◽  
Seismic Safety ◽  
Safety Margins

Current status of design basis earthquake level for nuclear power plant sites in several countries

2021 ◽  
Author(s):  
Hoseon Choi ◽  
Seung Gyu Hyun
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
South Korea ◽  
Seismic Activity ◽  
Nuclear Power ◽  
Current Status ◽  
Seismic Safety ◽  
Design Basis ◽  
Design Earthquake ◽  
Design Construction

<p>According to strict criteria step by step for site selection, design, construction and operation, the seismic safety of nuclear power plant (NPP) sites in South Korea are secured by considering design basis earthquake (DBE) level capable of withstanding the maximum ground motions that can occur on the site. Therefore, it is intended to summarize DBE level and its evaluation details for NPP sites in several countries.</p><p>Similar but different terms are used for DBE from country to country, i.e. safe shutdown earthquake (SSE), design earthquake (DE), SL2, Ss, and maximum calculated earthquake (MCE). They may differ when applied to actual seismic design process, and only refer to approximate comparisons. This script used DBE as a representative term, and DBE level was based on horizontal values.</p><p>The DBE level of NPP sites depends on seismic activity of the area. Japan and Western United States, where earthquakes occur more frequently than South Korea, have high DBE values. The DBE level of NPP sites in South Korea has been confirmed to be similar or higher compared to that of Central and Eastern Unites Sates and Europe, which have similar seismic activity.</p>

New Trends in Accurate Simulations for the Verification of Safety Margins in the Nuclear Power Plant Industry: Application of Virtual Performance Solution™ for the Response of Immersed Structures Subjected to Earthquakes

2011 ◽  
Author(s):  
Alain Tramec¸on ◽  
Jorg Kuhnert ◽  
Laurent Mouchette ◽  
Morgane Perrin
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Dynamic Simulations ◽  
Finite Point ◽  
Fluid Structure ◽  
Finite Element Software ◽  
Mesh Free ◽  
Safety Margins ◽  
Non Linear

Constraints on the safety of nuclear power plant components have increased recently along with the necessity to extend the lifespan of existing plants. For example, the acceleration levels to be sustained by the plant equipment during an earthquake have been increased many folds by the safety regulation agencies. Industrial and economic requirements plead for a verification of unknown safety margins, by accurate and physics based models taking into account all non-linear effects (for example contacts and fluid structure interaction). These effects are only approximately represented by standard linear analysis tools. Virtual Performance Solution (VPS), developed by ESI Group, includes (among other capabilities) a structural finite element software for non-linear, high velocity, dynamic simulations (PAM-CRASH), as well as a coupled, mesh free CFD module, FPM (Finite Point Method), developed in partnership with Fraunhofer ITWM. This solution accurately predicts fluid structure interactions, taking into account non-linear structural effects (contacts, friction, damping…) as well as complex fluid influences.

Seismic Analysis for an Explosion-Proof Valve Used in Nuclear Power Plant

2017 ◽  
Author(s):  
Juan Luo ◽  
Jiacheng Luo ◽  
Lei Sun
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Seismic Analysis ◽  
Nuclear Safety ◽  
Seismic Load ◽  
Seismic Safety ◽  
Stress Evaluation ◽  
Safety Standards ◽  
Stress And Deformation

Nuclear class equipment should be assessed for seismic safety before they are used in nuclear power plant. According to nuclear safety codes and regulations, all seismic category I equipments shall be designed enduring safety shutdown earthquake (SSE). That is, the stress evaluation needs to be accomplished for those structures. For some components, the deformation evaluation needs to be performed as well to assure the function integrity of the equipment. In this paper, the seismic analysis for an explosion-proof valve used in nuclear power plant, which exactly belongs to seismic category I equipment, has been conducted based on finite element method. The natural frequency, vibration mode and seismic response of the structure have been obtained through calculation, and the stress and deformation under the combined loadings of gravity, internal pressure, blast and seismic load have been evaluated according to ASME AG-1. The bolts of the structure have been qualified according to ASME III-NF as well. The results show that the design of the explosion-proof valve is in compliance with the requirement of corresponding nuclear safety standards.

Probabilistic seismic safety study of an existing nuclear power plant

1980 ◽  
Vol 59 (2) ◽  
pp. 315-338 ◽  
Author(s):  
R.P. Kennedy ◽  
C.A. Cornell ◽  
R.D. Campbell ◽  
S. Kaplan ◽  
H.F. Perla
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Safety Study ◽  
Seismic Safety

Analysis and Assessment of Errors of Commission in Nuclear Power Plant Settings

2000 ◽  
Vol 44 (22) ◽  
pp. 851-854
Author(s):  
Oliver Straeter
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Maintenance Management ◽  
Pressure Injection ◽  
Safety Margins ◽  
Plant Maintenance ◽  
Complex Technical Systems ◽  
Technical Systems ◽  
High Pressure Injection

The term Errors of Commission (EOC) describes a safety problem of complex technical systems where humans intervene into the system functions in an inappropriate way. Most serious events in any technical area are caused by EOCs. Humans shut down a high pressure injection that is needed in the current situation (TMI Nuclear Power Plant), humans decide to continue a test that brings the plant into serious conditions (Chernobyl Nuclear Power Plant), Maintenance Management does not exchange a wheel that is far below the safety margins (Eschede Railway Accident in Germany). Similar examples can be mentioned in other technical systems like Aircraft or Medicine for instance. This paper firstly gives an overview about the problem and the work in that field. It then focuses on some approaches for solution concerning the modeling of cognitive human behaviour.

Approach to Assess Influence of Earthquake-Induced Slope Collapse on Nuclear Power Plant Facilities

2018 ◽  
Vol 12 (04) ◽  
pp. 1841011
Author(s):  
Susumu Nakamura ◽  
Ikumasa Yoshida ◽  
Masuhiro Beppu
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Limit State ◽  
Landslide Risk ◽  
Total Probability ◽  
Assessment Procedure ◽  
Limit States ◽  
Seismic Safety ◽  
Slope Collapse

As a result of the disaster of nuclear power plant caused by the 2011 off the pacific coast of Tohoku Earthquake, establishment of a method to estimate the influence of slopes on the seismic safety of nuclear facilities has become necessary. The creation of such a method can yield important information regarding potential risk as well as risk management regarding seismic safety. The existing guidelines used to evaluate landslide risk provide guidance for landslide zoning as well as how landslide risk can be reduced and avoided. According to these guidelines, either people or houses are typically used as targets of risk evaluation. Particularly, for a specific slope, it is necessary to evaluate the damage of the potentially affected structures quantitatively and systematically. Therefore, the definition and basic assessment procedure of three limit states (stability limit, reachable limit and damage limit) are herein described. Furthermore, an evaluation case for a slope model describes the influence of slope collapse due to an earthquake. In this case, the fragility curves, as well as the occurrence probability for each limit state are described and an evaluation example is provided. Regarding new ideas and methods to evaluate the conditional reachable probability and the conditional damage probability as well as a method to evaluate the total probability of all three limit states are proposed. From the results obtained in our example case, it is found that systematical assessment of the risk information of facilities damaged due to slope collapse is useful, and is made possible via numerical analysis.

Code Developing of Fragility Analysis Program for Seismic Safety Evaluation of Nuclear Power Plant

2017 ◽  
Author(s):  
Zhao Wang ◽  
Jianfeng Yang ◽  
Weijin Wang ◽  
Bingchen Feng ◽  
Xiaoming Zhang
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Safety Evaluation ◽  
Seismic Fragility ◽  
Seismic Safety ◽  
Failure Frequency ◽  
Logic Operation ◽  
Seismic Safety Evaluation

For seismic safety evaluation method of nuclear power plant, nuclear power plant seismic margin analysis (SMA) and nuclear power plant seismic probability safety assessment (SPSA) are the most widely used methods. SMA is a method base on deterministic theory. Seismic capacity is valued by high confidence and low failure probability (HCLPF). Through the seismic failure logic of structure, system and components (SSCs), the method can calculated the HCLPF of the whole nuclear power plant, and verify whether the plant can withstand a SSE earthquake test. The SPSA method is the most widely used seismic safety assessment method based on probability theory. Through the analysis and quantification of earthquake accident sequence, a SPSA project can fully identify the seismic risk of nuclear power plant and seismic weak points. Also SPSA can guide the nuclear power plant seismic safety improvement. No matter which method is used to analyze the seismic safety of nuclear power plant, it is necessary to analyze and calculate the seismic fragility of the SSCs. SMA method needs to use a large number of HCLPF data, and seismic fragility analysis and calculation results is one of the main sources of HCLPF data. The SPSA method needs to use seismic fragility data of SSCs which are list in the seismic equipment list (SEL) as input data, so that it can support the quantitative analysis of the risk assessment model. Because of the existence of uncertainty, the seismic fragilities cannot be put to directly logic operation. This brings great difficulty to the using of fragility data. In the paper, the logic operation method and the uncertainty analysis method of seismic fragility is studied, and the calculation program is compiled based on the Monte Carlo method. In this paper, a program is used to calculate the case. The performance of the program is verified and the uncertainty of the system fragility is analyzed. Due to the existence of uncertainty, the fragility cannot put into the numerical calculation directly. In this paper, the calculation method of the failure frequency of components is studied, and the corresponding program is developed by using Monte Carlo method. In this paper, a program is used to calculate the failure frequency of the components under different ground motion levels, and the uncertainty of the failure frequency is also studied.

Review of Residual Stress Mitigation Methods for Application in Nuclear Power Plant

2006 ◽  
Author(s):  
P. R. Hurrell ◽  
D. Everett ◽  
A. Gregg ◽  
S. Bate
Keyword(s):  
Residual Stress ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Cost Savings ◽  
Surface Plastic ◽  
Significant Treatment ◽  
Thermal Transients ◽  
Safety Margins ◽  
Mitigation Methods

A research project has recently been launched in the UK investigating residual stress (RS) in nuclear power plant [1]. At the outset there is a need to review techniques available for modifying/relieving residual stress levels in weldments, since it is well known that large tensile RS levels generated in welds can be detrimental in terms of fatigue, fracture resistance and environmentally assisted cracking (EAC). Therefore current RS mitigation methods have been reviewed. Mitigation methods can be categorised into three main groups as follows: a) Surface treatment to induce compressive skin stress; b) Stress relief through thickness; c) Weld design optimisation to produce low/favourable RS levels and minimize distortion. A brief description is provided of how each method works, together with the capability and potential benefit in terms of RS reduction, as well as references for further information. Metallurgical effects of treatment are also an important consideration. The practicality of application to nuclear plant is considered, both in manufacture and in-service, together with any limitations and risks. Several techniques are identified that are likely to be beneficial and warrant funding for further development. RS mitigation should be targeted at key/critical weld locations in the plant, where loadings and degradation mechanisms (such as corrosion, fatigue, EAC or fracture) are most significant. Treatment would be carried out in order to improve plant integrity and reliability (eg safety margins). There are potentially substantial cost savings since through-life inspection/maintenance work could be reduced and expensive repairs and shutdowns avoided. Note that it is important to understand whether the benefits in terms of RS improvement are likely to be long term. In certain systems large thermal transients are applied that might generate additional surface plastic strains, thereby modifying RS magnitudes and distributions.

Seismic Design Margin of the Piping and Support System: Part 3—Evaluation of Seismic Margin of the Piping System

2010 ◽  
Author(s):  
Eiji Shirai ◽  
Takanori Yamada ◽  
Kazutoyo Ikeda ◽  
Toshiaki Yoshii ◽  
Masami Kondo ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Support System ◽  
Earthquake Engineering ◽  
Nuclear Power ◽  
System Response ◽  
Piping System ◽  
Linear Modeling ◽  
Safety Margins ◽  
Non Linear

Seismic safety is one of the major key issues of nuclear power plant safety in Japan. It is demonstrated that nuclear piping possesses large safety margins through the piping and support system test, which consisted of three dimensional piping, supports, U-bolts, and concrete anchorages, using the E-defense vibration table of National Research Institute for Earth Science and Disaster Prevention, Hyogo Earthquake Engineering Research Center, on extremely high seismic excitation level [1,2,3]. In the above test, the non-linear hysteretic behaviors of the support are quite complicated, but the dissipated energies introduce large damping effects on the piping system response. In order to evaluate the inelastic behavior of the support with respect to the whole piping system response, the following simulation methodology for the support re-evaluation is proposed. 1) Non-linear modeling of the support: • Failure mode and failure capacity of each support. • Simplified non-linear modeling of each support. 2) Simulation Analysis of the piping and support system: • Considering the non-linearity both of the supports and elbows in the piping system. 3) Evaluation of seismic margin: • Focused on the failure level for the support system, and the fatigue damage for the strain range of the piping. The limit state analysis of the typical piping system of a nuclear power plant is presented in this paper, and it is demonstrated that these evaluations of the seismic margins would give important insight into the support reinforcement program on the seismic re-evaluation work.

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