Chimney Walls Behavior When Submitted to an Internal Explosion

2002 ◽  
Author(s):  
B. Autrusson ◽  
G. Milcent
Keyword(s):  
Power Plants ◽  
Numerical Models ◽  
Three Dimensional ◽  
Time Sequence ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Concrete Walls ◽  
Reflected Waves ◽  
Internal Explosion ◽  
Fuel Reprocessing

The nuclear fuel reprocessing or fabrication and power plants must be assessed for a set of various normal and accidental situations including explosions due to either operation hazards or malevolent acts. In order to evaluate the consequences of such an aggression in terms of damage to the plants and of radiological release in the environment, IRSN has launched a program including experiments and development of numerical models concerning the behavior concrete walls which are parts of plants. The purpose of this document is to present numerical simulations of chimney wall behavior when submitted to an internal explosion. The simulation uses a three dimensional model with a finite element code. The wave propagation is estimated including the reflection on the wall (the combination between the incident wave and the reflected waves, the attenuation). The detonation simulation is done in considering the walls at rest. The dynamic response of the structure is an estimation relating the time sequence in which the pressure is applied on the surrounding walls. The concrete and iron reinforcements have been taken into account. The stresses, strains and the percentage of cracks in wall are estimated.

Influence of Lined Pipe Fabrication on Liner Wrinkling

2019 ◽  
Author(s):  
Ilias Gavriilidis ◽  
Spyros A. Karamanos
Keyword(s):  
Plastic Material ◽  
Numerical Models ◽  
Three Dimensional ◽  
Local Buckling ◽  
Short Wave ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Imperfection Sensitivity ◽  
Elastic Plastic ◽  
Outer Pipe

Abstract An economical method to protect offshore pipelines against corrosive ingredients of hydrocarbons is a double-walled (also called “lined” or “bi-metallic”) pipe, in which a thick-walled low-alloy carbon steel (“outer pipe”) is lined internally with a thin layer (“liner pipe”) from a corrosion resistant alloy material. During the deep-water installation, a lined pipe is subjected to severe plastic loading, which may result in detachment of the liner pipe from the outer pipe forming short-wave wrinkles, followed by local buckling. In the current study, alternative lined pipe manufacturing processes are investigated, including elastic, plastic hydraulic and thermo-hydraulic expansion of the outer pipe, for different initial gaps between the two pipes. The problem is solved numerically, accounting for geometric non-linearities, local buckling phenomena and elastic-plastic material behaviour for both the liner and outer pipe. Two types of numerical models are developed, a quasi-two-dimensional model, examining the mechanical bonding between the pipes, and a three-dimensional model, repeating the manufacturing process and investigating its effect on the mechanical behaviour of a lined pipe subjected to monotonic bending. In addition, the influence of initial geometric imperfections on liner pipe buckling is investigated, showing the imperfection sensitivity of the lined pipe bending behaviour, for each fabrication process.

Modelling the global sources and sinks of radiatively active gases

1995 ◽  
Vol 351 (1696) ◽  
pp. 397-411 ◽  
Keyword(s):  
Numerical Models ◽  
Stratospheric Ozone ◽  
Trace Gases ◽  
Three Dimensional ◽  
Relative Importance ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Sources And Sinks ◽  
Two Dimensional Model

The use of numerical models in understanding the budgets of atmospheric trace gases is discussed. The budget of methane is calculated in a two-dimensional model. The contrasting behaviour of the Northern and Southern Hemisphere reflects changes in the relative importance of emissions, transport and chemistry. Models can also be used to test hypotheses. An example of such a study is presented in which it is shown that changes in stratospheric ozone could have played a significant role in the dramatic change in methane trend observed in the early 1990s. Finally, use of a three-dimensional model to study tropospheric trace gases is introduced.

Impact of the Level of Approximation on Modeling Flushing Waves

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
P. Staufer ◽  
J. Dettmar ◽  
J. Pinnekamp
Keyword(s):  
Shear Stress ◽  
Numerical Models ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Bottom Shear Stress ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Successful Operation ◽  
One Dimensional ◽  
The One

Sewer cleaning with the means of flushing offers the possibility to place sewers free of deposit if flushing waves are generated continuously or quasi-continuously by suitable flushing devices. Numerical investigations should be carried out regarding different hydraulic circumstances because sewer networks consist of various compounds with complex geometries e.g. cross-section alignment or special structures. To accomplish a stable and successful operation of flushing devices it seems necessary to use different level of approximation on modelling flushing waves. Thereby both accuracy and running-time of simulations with numerical models will be optimized. This paper presents differences and similarities of the simulation results of a one-dimensional and a three-dimensional model of flushing wave within a big sized sewer. As assumed the one-dimensional model becomes less accurate when the complexity of the geometry increases. The three-dimensional model shows an underestimation of velocity and bottom shear-stress at the flushing head due to energy losses within the water body. Contrary, the one-dimensional model overestimates bottom shear-stress at the flushing head because of a stationary basic approach which is used. However, real highly resolved measurements of bottom shear-stresses are required to confirm the results in detail.

Development of Seismic Countermeasures Against Cliff Edges for Enhancement of Comprehensive Safety of Nuclear Power Plants: Cliff Edges Relevant to NPP Building System

2018 ◽  
Author(s):  
Akemi Nishida ◽  
Byunghyun Choi ◽  
Hidemasa Yamano ◽  
Tsuyoshi Takada
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Retaining Wall ◽  
Three Dimensional ◽  
Isolation Effect ◽  
Response Analysis ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Seismic Safety

This study identified and quantified possible cliff edge effects through a seismic safety evaluation of a nuclear power plant, based on the concepts of risk and defense in depth. Cliff edges of the both physical and knowledge-oriented type were considered in this study. We investigated a seismic isolation effect, etc., for physical cliff edges, and the modeling of the target structure, boundary conditions, etc., for knowledge-oriented cliff edges. Response analysis was performed using a sway-rocking (SR) model and a three-dimensional model of the target building. The seismic isolation effect of the base-isolated building was confirmed by comparison to the results of earthquake-resistant building. In the case of a collision with the retaining wall of the base-isolated building, the level of damage was found to depend on the modeling of the collision condition assumed. On the other hand, the study confirmed the differences between the results from the SR model and the three-dimensional model. And the greater fidelity of the three-dimensional model was also confirmed. This paper presents and discusses these results.

Optimization of the Code of the Numerical Magnetosheath-Magnetosphere Model

2013 ◽  
Vol 43 (2) ◽  
pp. 77-82 ◽  
Author(s):  
P. Dobreva
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Element Model ◽  
Code Optimization ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Characteristic Model ◽  
Gas Dynamic ◽  
First Results ◽  
Numerical Performance

Abstract The proposed three dimensional model contains two earlier developed 3D regional numerical models: a grid-characteristic model of the magnetosheath and a finite element model of the magnetosphere. The model output is the distribution of gas-dynamic parameters in the magnetosheath and of magnetic field inside the magnetosphere. The efforts are focused on the modernization of the existing software, written in Fortran, using several techniques for parallel programming such as OpenMP extensions. After analyzing the numerical performance of the model a possible scenario for the code optimization is shown. First results with the improved variant of the model are presented.

Three-Dimensional Model for Virtual Surgical Simulation, during Complex Skull Base Surgery and Aneurysm Surgery

Skull Base ◽  
2008 ◽  
Vol 18 (S 01) ◽  
Author(s):  
Akio Morita ◽  
Toshikazu Kimura ◽  
Shigeo Sora ◽  
Kengo Nishimura ◽  
Hisayuki Sugiyama ◽  
...  
Keyword(s):  
Skull Base ◽  
Surgical Simulation ◽  
Skull Base Surgery ◽  
Three Dimensional ◽  
Aneurysm Surgery ◽  
Dimensional Model ◽  
Three Dimensional Model
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