scholarly journals Dynamic behaviour of nuclear island structure of AP1000 under El Centro and Dien Bien earthquakes

2021 ◽  
Vol 7 (4) ◽  
pp. 34-41
Author(s):  
Lam Dong Vu Lam ◽  
Ngoc Dong Pham ◽  
Dinh Kien Nguyen ◽  
Dai Minh Nguyen ◽  
Tien Thinh Do
Keyword(s):  
Finite Element ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Dynamic Response ◽  
Dynamic Behavior ◽  
Nuclear Power ◽  
Seismic Analysis ◽  
Element Model ◽  
Island Structure ◽  
Finite Element Software

AP1000 is a nuclear power plant developed by Westinghouse based on an advanced passive safety feature, and it is one of selected technologies for Ninh Thuan 2 Nuclear Power Plant. The dynamic behavior of the plant under earthquakes is the most concerned in design and construction of the plant. This paper presents a seismic analysis of the AP1000 nuclear island structure by using the computational finite element software ANSYS. A 3D finite element model for the structure is developed and its dynamic response, including the time histories for displacements, velocities andaccelerations, deformed configurations and von Mises stresses of the structure are obtained for America El Centro (6.9 Richter) and Vietnam Dien Bien (5.3 Richter) earthquakes. A comparison on the dynamic response of the structure under the two earthquakes is given, and the dynamic behavior of the structure under the earthquakes is discussed.

Simulation of Behaviors of a One-Third Scale Containment Model Test

2017 ◽  
Author(s):  
Guopeng Ren ◽  
Rong Pan ◽  
Feng Sun
Keyword(s):  
Finite Element ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Nuclear Power ◽  
Element Model ◽  
Scale Model ◽  
Prestress Losses ◽  
The Finite Element Model

Reactor containment of a nuclear power plant is a structure to ensure the safety of nuclear power plant. It acts as the last barrier to prevent the release of radioactive materials from NPP during accidents. Finite element models were established to simulate a 1/3 scale model of a reactor containment building under leakage test pressure. General finite element software ANSYS were applied. The nonlinear behavior of containment materials, geometric were taken into account in the analysis. The reliability of the finite element model was verified through the comparison of theoretical analysis results with experimental results. In the ANSYS finite element model, the concrete, steel bars and prestress tendons were separated and the prestress tendons were considered by the method of cooling method on the prestress tendon elements. The mechanical properties of the finite element model in the prestress tension process and the absolute internal pressure of 0.52MPa were analyzed. Transient and time dependent losses were taken into account at the same time during the calculation of prestress of tendons, so as to calculate effective prestress at different locations of tendons. Calculation results of prestress losses show that the prestress losses at the hole of equipment hatch are larger than the other areas. The results show that, the deformation of over-all structure of the containment is shrink inward under the action of prestress. And the simulation can achieve the consistent deformation effect between tendons and concrete. The maximum radial displacement of the whole containment structure is located at of 10 ° ∼ 20 °area on the right of the hole of the gate. The effect of expansion deformation of the containment caused by design internal pressure is insufficient to offset the inward shrink effect generated by tendons, and the over-all structure of the concrete containment scale model is mainly under compressive stress. The containment test model is still with a large safety margin under the action of design internal pressure. The largest tensile stress is on the up and down areas of the internal sides of the equipment hatch, dome area close to ring beam, and bottom of perimeter wall close to the base slab. There is possibility of cracking on the concrete in limited local zones. This benchmark can provide a reference for engineering design of containment.

scholarly journals Structural Safety Analysis Based on Seismic Service Conditions for Butterfly Valves in a Nuclear Power Plant

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Sang-Uk Han ◽  
Dae-Gyun Ahn ◽  
Myeong-Gon Lee ◽  
Kwon-Hee Lee ◽  
Seung-Ho Han
Keyword(s):  
Finite Element ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Finite Element Model ◽  
Nuclear Power ◽  
Dynamic Properties ◽  
Element Model ◽  
Structural Safety ◽  
Butterfly Valve ◽  
Design Response Spectrum

The structural integrity of valves that are used to control cooling waters in the primary coolant loop that prevents boiling within the reactor in a nuclear power plant must be capable of withstanding earthquakes or other dangerous situations. In this study, numerical analyses using a finite element method, that is, static and dynamic analyses according to the rigid or flexible characteristics of the dynamic properties of a 200A butterfly valve, were performed according to the KEPIC MFA. An experimental vibration test was also carried out in order to verify the results from the modal analysis, in which a validated finite element model was obtained via a model-updating method that considers changes in thein situexperimental data. By using a validated finite element model, the equivalent static load under SSE conditions stipulated by the KEPIC MFA gave a stress of 135 MPa that occurred at the connections of the stem and body. A larger stress of 183 MPa was induced when we used a CQC method with a design response spectrum that uses 2% damping ratio. These values were lower than the allowable strength of the materials used for manufacturing the butterfly valve, and, therefore, its structural safety met the KEPIC MFA requirements.

scholarly journals Seismic Analysis of AP1000 Nuclear Island Structure by Using the Finite Element Software ANSYS

2017 ◽  
Vol 20 (K2) ◽  
pp. 14-23
Author(s):  
Kien Dinh Nguyen ◽  
Dong Lam Vu
Keyword(s):  
Finite Element ◽  
Seismic Analysis ◽  
Element Model ◽  
Relative Displacement ◽  
Maximum Displacement ◽  
Acceleration Time ◽  
Island Structure ◽  
Finite Element Software ◽  
Acceleration Time Histories ◽  
Time Histories

Seismic analysis of AP1000 nuclear island structure by using the commercial finite element software ANSYS is presented. Using the ANSYS Workbench, a sophisticated threedimensional finite element model of the structure is created and employed in the analysis. Dynamic response of the structure to both the one-directional and three-directional acceleration time histories are considered in the analysis. The time histories for the relative displacement, velocity and absolute acceleration of the structure are obtained for various earthquakes, including American El Centro, Japanese Kobe and Vietnamese Dien Bien earthquakes. The numerical results show that the dynamic characteristics obtained by using one-directional and thee-directional acceleration time histories are different, and the three three-directional acceleration time histories should be employed in the seismic analysis. The result also reveals that the nuclear island is safer in Dien Bien earthquake that it is in El Centro and Kobe earthquakes. The distribution of the von Mises stresses of the structure according to the maximum displacement at the top point is also examined and highlighted.

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.

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