Dynamic characteristics of KALIMER IHTS hot leg piping system conveying hot liquid sodium

2000 ◽  
Vol 77 (11) ◽  
pp. 679-689 ◽  
Author(s):  
G.H. Koo ◽  
B. Yoo
Keyword(s):  
Dynamic Characteristics ◽  
Liquid Sodium ◽  
Piping System

Research and Design of the Sodium Steam Filter System in Large Liquid Metal Cooled Fast Reactors

2017 ◽  
Author(s):  
Wang Leijian ◽  
Lu Yuan ◽  
Xiao Changzhi
Keyword(s):  
Free Surface ◽  
Chemical Properties ◽  
Liquid Sodium ◽  
Thermal Calculation ◽  
Piping System ◽  
Filtration Process ◽  
Active Chemical ◽  
High Boiling Point ◽  
Research And Design ◽  
Thermal Physical Properties

This reactor uses liquid sodium as coolant owing to its good thermal physical properties, high boiling point and compatibility of cladding material. However, the sodium has a very active chemical properties, for which the free surface of sodium must be protected by inert gas. In the high temperature environment, the sodium atoms diffusion to cover gas slowly, forming a mixed atmosphere that contained large amount of sodium steam. Sodium steam is covered with the free surface of sodium. Then metal sodium will solidify in the inner wall of the pipe or correlative valves with the reduced temperature. This reactor needs to collect and filter sodium steam in order to reduce the hazards to the equipment, piping system, valves and the other devices. Based on the previous research about the purification process of sodium, this paper compared different steam trapping filtration process and carried out the thermal calculation providing basis for research and design of large sodium cooled fast reactor sodium steam trapping filtration process and establishing a reliable sodium steam filtering system.

Dynamic Characteristics of Structure With Bolted Joint Considering Some Factors

2004 ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Random Excitation ◽  
Pressure Vessels ◽  
Bolted Joints ◽  
Piping System ◽  
Bolted Joint ◽  
Earthquake Excitation ◽  
Applied Torque

Bolted joints are widely used for pressure vessels and piping system. Many studies on strength and stiffness of bolted joint are carried out. However, few studies on the dynamic characteristics of structure with bolted joint are carried out. The dynamic characteristics are important for design of structure subjected to earthquake excitations. In this paper, the effect of bolted joints on dynamic characteristics of structure is examined. First, the damping ratio and the natural frequency of specimens with some types of bolted joints are measured. Those are obtained for some factors, amplitude of excitation, applied torque. Obtained results are compared with those for the specimen without bolted joint. It is found that the damping ratio increases and the natural frequency becomes lower. Next, modeling of the bolted joint is presented. The bolted joint is modeled using additional mass, stiffness and damping elements. Finally, using model of bolted joint, response of the structure with bolted joint subjected to earthquake excitation is examined. Earthquake excitation is modeled as stationary random excitation. Mean square values of the response are obtained. Standard deviation of the acceleration response of the structure with bolted joint are lower than those without bolted joint.

Effects of Uncertainties in Boundary Conditions on Dynamic Characteristics of Industrial Plant Components

2014 ◽  
Author(s):  
Oreste S. Bursi ◽  
Giuseppe Abbiati ◽  
Luca Caracoglia ◽  
Md Shahin Reza
Keyword(s):  
Boundary Conditions ◽  
Dynamic Characteristics ◽  
Seismic Risk ◽  
Dynamic Properties ◽  
Fragility Curves ◽  
Structural Safety ◽  
Industrial Plant ◽  
Piping System ◽  
Uncertain Boundary ◽  
Plant Components

Seismic risk assessment of industrial plants is of paramount importance to ensure adequate design against earthquake hazards. Seismic vulnerability of industrial plant components is often evaluated through a fragility analysis to conform to structural safety requirements. Fragility curves of single components are usually developed by neglecting the effect of actual boundary conditions. Thus, an incorrect evaluation of individual fragility curves can affect the overall fragility curve of a system. This may lead to “erroneous” seismic risk evaluation for a plant in comparison with its real state. Hence, it is important to study the effect of uncertainties, introduced at the boundaries when coupling effects are neglected, on the dynamic characteristics of a system. Along this line, this paper investigates the effects of uncertain boundary conditions on the probability distributions of the dynamic properties of a simple chain-like system with increasing number of degrees of freedom. In order to describe the uncertain boundary condition, a modified version of the well-known β distribution is proposed. Subsequently, the Analytical Moment Expansion (AME) method is employed to estimate the statistical moments of the output random variables as an alternative to more computationally-demanding Monte Carlo simulations. Finally, a preliminary extension of the proposed approach to a realistic piping system connected to a class of broad/slender tanks is discussed.

Experimental Study of Mechanical Pipe Snubber Seismic Behavior

1997 ◽  
Vol 119 (3) ◽  
pp. 384-388 ◽  
Author(s):  
D. K. Nims ◽  
J. M. Kelly
Keyword(s):  
Experimental Study ◽  
Dynamic Characteristics ◽  
Seismic Behavior ◽  
Full Scale ◽  
Hysteretic Behavior ◽  
Scale Model ◽  
Piping System ◽  
Complicated Pattern ◽  
Seismic Tests ◽  
Input Motion

A series of seismic tests of mechanical snubbers on a full-scale model piping system provided a unique opportunity for detailed scrutiny of snubber seismic behavior on an actual piping system. The observed snubber behavior is a complicated pattern of braking and releasing, drag and drift, and the dynamic characteristics of the snubber, as well as the input motion, play a role in the response of the snubber. The snubbers were effective in limiting pipe displacements. Relative accelerations across the snubber were larger than expected. Snubber hysteretic behavior was irregular. Results from this testing are important in understanding snubber behavior, evaluating snubber performance, and in assessing alternatives to snubbers.

Dynamic Response Studies of Piping-Support Systems

1990 ◽  
Vol 112 (1) ◽  
pp. 39-45 ◽  
Author(s):  
T. Chiba ◽  
R. Koyanagi
Keyword(s):  
Dynamic Characteristics ◽  
Support Systems ◽  
Three Dimensional ◽  
Local Stress ◽  
Integrated Approach ◽  
Piping System ◽  
3 Dimensional ◽  
Piping Systems ◽  
Seismic Loadings ◽  
High Level

Considering the effect of the interaction between piping and support systems in the piping design is a more integrated approach to improve the reliability of piping systems. So, it is important to clarify the dynamic characteristics of the piping and the restraint structure during the seismic events. It may be desirable to investigate the effect of the gap on the response and the local stress of the piping systems. The dynamic characteristics of a simplified piping model with gaps was investigated by the tests and the analysis. Three-dimensional piping model test was performed to estimate the effect of the gap on the response of the piping system. It can be found that the local stress and the stiffness of the piping and the restraint structure under the seismic loadings should be considered in the seismic design. The gap size was not so effective on the response of the 3-dimensional piping system in the high-level response.

Effects of Inline Rotating Component on Piping System Dynamic Characteristics

2003 ◽  
Author(s):  
Zakaria N. Ibrahim
Keyword(s):  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Normal Modes ◽  
Degree Of Freedom ◽  
System Dynamic ◽  
Piping System ◽  
Problem Solution ◽  
Rotating Shaft ◽  
Eigen Value ◽  
Quick Assessment

Piping system dynamic characteristics are determined utilizing the classical Eigen-Value problem solution. Systems with integrated inline rotating components would experience some changes in these characteristics. The intensity of these changes depends on the relative magnitudes of their rotational momentums. Pseudo single degree of freedom ‘SDOF’, systems that include gyroscopic momentum of a rotating shaft are formulated and are subjected to seismic base excitations. The comparative responses of these SDOF are investigated. The gyroscopic inertia significantly alters their predicted seismic responses. For multi-degree of freedom system, simplified methodology is formulated to provide quick assessment of including the gyroscopic effects of the rotating components. The lumped parameters of the inline-rotating component within the piping system require the velocity degrees of freedom to be included in the analysis. This results in the non-classical Eigen-Value problem type of formulation. The latter is simplified utilizing the classical Eigen-Value solution conventionally termed as normal modes extraction. The normal modes synthesis reduces the number of degrees of freedom for the non-classical Eigen-Value problem to a manageable level. The concept of mode shape utilization coefficient ‘MSUC’, is introduced to provide quick assessment of the system. The gyroscopic inertia does not dominate the system dynamic characteristics. Low to moderate rotational momentums, typically installed by the industry, slightly affect the piping system dynamic characteristics. This justifies the industry practice of ignoring the rotational momentums within the piping systems routine analysis. It is also found that very high rotational momentums are artificially required to dramatically change the system dynamic characteristics.

scholarly journals Anti-seismic characteristics of safety valve and its spring failure prediction analysis

2020 ◽  
Vol 306 ◽  
pp. 04004
Author(s):  
Fanrong Meng ◽  
Huibing Zhang ◽  
Ye Dai ◽  
Hanbo Zhang ◽  
Wenqiang Wei ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Dynamic Characteristics ◽  
Nuclear Power ◽  
Safety Valve ◽  
Nuclear Safety ◽  
Working Environment ◽  
Response Analysis ◽  
Piping System ◽  
Valve Body

Safety valve is an important guarantee for nuclear power plant system. Its working environment is harsh, and medium is high-temperature corrosive. It is important to study the dynamic characteristics of nuclear safety valve under unsteady condition to improve the stability and safety of nuclear power plant piping system. Using the finite element method, mass simplification and Rayleigh method, the frequency response analysis of the safety valve and the spring is predicted to predict the seismic capacity under the earthquake load. Based on the verification of the dynamic characteristics of the valve body, the stress and strain analysis of the spring is carried out. To explore the failure condition of the safety valve spring, the lateral deviation linearity of the spring was tested and analyzed by setting up the offset test bench. The results show that the safety valve with the above analysis method can meet the working requirements under the shaking condition. The research results provide an important theoretical basis for the design and analysis of nuclear safety valves.

Dynamic Analysis of NPP Piping Systems and Components With Viscoelastic Dampers Subjected to Severe Earthquake Motions

2016 ◽  
Author(s):  
Ichiro Tamura ◽  
Masashi Kuramasu ◽  
Frank Barutzki ◽  
Daniel Fischer ◽  
Victor Kostarev ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Characteristics ◽  
Seismic Analysis ◽  
Dynamic Properties ◽  
Maxwell Model ◽  
Shaking Table ◽  
Nonlinear Dependence ◽  
Piping System ◽  
Frequency Dependent ◽  
Viscoelastic Dampers

In Shimane nuclear power plant of Chugoku Electric Power Co., a number of safety improvements are planned to be implemented aiming for the highest level of safety in the world to be achieved. One of the new safety measures is the application of viscoelastic dampers for seismic protection of safety related piping system and components. High performance of viscoelastic dampers has been confirmed by direct testing of the piping natural scale model at the shaking table subjected to severe seismic accelerations up to 20 m/s2. However, viscoelastic dampers as a dynamic protection device have frequency-dependent dynamic characteristics, which are difficult to reproduce in the frame of conventional seismic analysis based typically on the use of response spectrum method. For example, the dynamic properties of viscoelastic dampers exhibit nonlinear dependence on dissipation energy, shear rate of viscous fluid, and temperature. Method for Seismic analysis of systems with viscoelastic dampers (SAVD-Method) is one of the analytical approaches capable of considering the dynamic properties and nonlinear behavior of viscoelastic dampers. The SAVD-Method is a comparatively simple but reliable approach for dynamic analysis of a piping system and components with viscoelastic dampers. Frequency-dependent dynamic characteristics of the viscoelastic dampers are able to be modeled by a four-parameter Maxwell model. To consider the nonlinearity of the dynamic properties of viscoelastic dampers, the Maxwell model parameters were determined for different usage conditions in conjunction with the adjustment dependent on the energy dissipation criteria. Direct comparison of the shaking table measurements and analysis according to SAVD-method shows good matching of results for all controlled parameters and levels of seismic excitation.

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