Analysis of Seismic Experiment of Hexagonal Multi Bundle Model Using Core Assembly Mock-Up

2020 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Shinichiro Matsubara ◽  
Hidenori Harada ◽  
Tomohiko Yamamoto
Keyword(s):  
Fast Reactor ◽  
Three Dimensional ◽  
Reactor Core ◽  
Vertical Direction ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
The Core ◽  
Vibration Behavior ◽  
Seismic Experiment ◽  
Core Elements

Abstract The fast reactor core is composed of hundreds of core elements that stand independently on the core support plate, but does not have support to constrain vertical displacement in order to avoid effects such as thermal elongation. When the earthquake occurs, the group vibration behavior is shown, including the rising of core elements in vertical direction, the collision with adjacent core elements in horizontal direction, and the fluid structure interaction. The three dimensional core group vibration analysis code (REVIAN-3D) was constructed to evaluate them. In the case of fast reactor cores in Japan, the horizontal displacement of core elements at the outermost periphery is restricted by the core former (core barrel). However, since there is no core former in fast reactors other than Japan and the boundary conditions are different from those in Japan, the vibration behavior also differs. In this study, to grasp and estimate the group vibration behavior with and without a core former under the earthquake motion, seismic experiment of hexagonal multi bundle model using core assembly mock-up was conducted [1]. These test results show that the horizontal displacements are larger and impact force between pads of core assembly mock-up is smaller without the core former. In this paper, the analysis was verified by group vibration tests with and without a core former.

Experimental Study on the Effect of Core Support Frame on Seismic Behavior of Fast Reactor Core

2020 ◽  
Author(s):  
Shinichiro Matsubara ◽  
Akihisa Iwasaki ◽  
Hidenori Harada ◽  
Tomohiko Yamamoto
Keyword(s):  
Fast Reactor ◽  
Three Dimensional ◽  
Reactor Core ◽  
Vertical Direction ◽  
Vertical Displacement ◽  
Test Results ◽  
Core Element ◽  
Vibration Behavior ◽  
Seismic Experiment ◽  
Core Elements

Abstract The fast reactor core is composed of hundreds of core elements that self-stand on the lower support plate, and core elements does not have support to constrain vertical displacement in order to avoid effects such as thermal elongation. When an earthquake occurs, the group vibration behavior including the rising of core elements in the vertical direction, the collision with adjacent core elements in the horizontal direction, and the fluid structure interaction is observed. The three dimensional core group vibration analysis code (REVIAN-3D) for evaluating these has been constructed. In this study, to grasp and estimate the group vibration behavior with and without a core former under the earthquake motion, seismic experiment of hexagonal multi bundle model using core element mock-up was conducted. These test results show that the presence of the core former decrease the horizontal displacements and increases core compaction. And the test results are used for the verification data of the analysis code REVIAN-3D.[1]

Effect of Deformation of Core Elements of Fast Reactor Core to the Seismic Response

2019 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Shinichiro Matsubara ◽  
Kazuteru Kawamura ◽  
Hidenori Harada ◽  
Tomohiko Yamamoto
Keyword(s):  
Thermal Expansion ◽  
Fast Reactor ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Reactor Core ◽  
Axial Direction ◽  
Vertical Displacement ◽  
Analysis Model ◽  
The Core ◽  
Core Elements

Abstract Core elements of a fast reactor are self-standing on the core support structure and not restrained in the axial direction. When the earthquake occurs, it is necessary to consider vertical behavior and horizontal displacement of the core elements simultaneously. In the core seismic analysis, a three dimensional core vibration behavior was evaluated by considering fluid structure interaction, collision with adjacent core elements and vertical displacement and verified by a series of vibration tests. But the evaluation had a assumption of straightness of each core elements which may be bowed due to thermal expansion and swelling under restraint of the horizontal direction between the upper pad and lower structure (Entrance Nozzle). If the core elements are deformed in its plant operation, they may push each other against its adjacent core elements. The large horizontal interference forces may work to decrease the vertical displacement of the core elements. In this study, to grasp and estimate the behavior under the deformed core elements under the earthquake motion, a three dimensional seismic analysis model consist of all of core elements with consideration of the effect of deformed core elements were prepared, analyzed and verified by hexagonal-matrix tests with 37 core elements and single row mock-up models with 7 core elements. These test results show that the rising displacements decrease with increased deformation and no rising occurs when the deformations exceed a threshold. In this paper, the effect of bending deformation due to thermal expansion and swelling on the rising displacement of the core elements was shown by seismic experiments.

Fast Reactor Core Seismic Analysis for Verification of Assessment Model Considering Deformation of Core Elements

2019 ◽  
Author(s):  
Shinichiro Matsubara ◽  
Akihisa Iwasaki ◽  
Kazuteru Kawamura ◽  
Hidenori Harada ◽  
Tomohiko Yamamoto
Keyword(s):  
Fast Reactor ◽  
Seismic Analysis ◽  
Evaluation Model ◽  
Reactor Core ◽  
Vertical Displacement ◽  
Core Element ◽  
Structure Interaction ◽  
The Core ◽  
Core Elements ◽  
Vertical Displacements

Abstract To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Thus, a core seismic analysis method has been developed to evaluate 3D core vibration behavior considering fluid structure interaction and vertical displacements (rising). The analysis code is verified by a series of vibration tests. The evaluation model to simulate the influence of core element deformation due to heat and irradiation were developed and the analysis of the seismic test was performed. And the evaluation model was verified by comparing the seismic test and analysis results. A fast reactor core consists of hundreds of core elements, which lengthen due to thermal expansion and swelling. So, the core elements are self-standing on the core support structure and not restrained in the axial direction. When the vertical seismic excitation surpasses gravitational acceleration, it is necessary to consider vertical displacements and horizontal displacements of the core elements simultaneously. This 3-D vibration behavior is affected by the fluid loads from ambient coolant and the interference of surrounding structures. To solve this, the influential factors to vibration behaviors due to the structure and fluid body, including fluid structure interaction, are extracted and the 3-D reactor core group vibration analysis code (REVIAN-3D) is developed. Core elements are deformed due to thermal expansion and irradiation, and are interfered with surrounding elements each other. The interference increases the frictional force acting on the core element and reduce the vertical displacement (rising) of the core element during the earthquake. To evaluate this reduction of rising, the evaluation model simulating this deformation is incorporated in REVIAN-3D. In this study, the analysis of the vibration test was carried out using the new incorporated evaluation model. As the deformation of mock-up increases, the vertical displacement (rising) decreases, and when the initial interference due to deformation exceeds the threshold, no rising occurs. This trend agreed well between the vibration test and analysis. It is verified that the new incorporated evaluation model simulates the test result enough.

Development of a Core Seismic Analysis Method for a Fast Reactor

2016 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Kazuo Hirota ◽  
Masatsugu Monde ◽  
Shinichiro Matsubara ◽  
Iwao Ikarimoto
Keyword(s):  
Fast Reactor ◽  
Seismic Analysis ◽  
Reactor Core ◽  
Great Earthquake ◽  
Analysis Method ◽  
Core Element ◽  
The Core ◽  
Vibration Behavior ◽  
Core Elements ◽  
Core Seismic Analysis

A fast reactor core consists of several hundreds of core assemblies, which are hexagonal flexible beams embedded at the lower support plate in a hexagonal arrangement, separated by small gaps, and immersed in a fluid. Core assemblies have no support for vertical fixing in order to avoid the influence of thermal expansion and swelling. These days, in Japan, it has become necessary to postulate huge earthquakes in seismic evaluations. If a great earthquake occurs, the large displacement and impact force in each core assembly may cause problems with control rod insertability and core assembly strength. So, it is necessary to grasp the vibration behavior of the core elements during an earthquake in order to appropriately design the core support structures and core elements of a fast reactor. Thus, considering horizontal and vertical forces (impact forces and fluid forces) acting on the core elements during an earthquake, a core seismic analysis method has been developed to evaluate 3D core vibration behavior considering fluid structure interaction and vertical displacements (rising). This paper summarizes the details of the core element vibration analysis code in 3D (REVIAN-3D) that has been developed.

CFD Investigation of Thermal-Hydraulic Behaviors in Full Reactor Core for Sodium-Cooled Fast Reactor

2018 ◽  
Author(s):  
Jing Chen ◽  
Dalin Zhang ◽  
Suizheng Qiu ◽  
Kui Zhang ◽  
Mingjun Wang ◽  
...  
Keyword(s):  
Fast Reactor ◽  
Power Distribution ◽  
Three Dimensional ◽  
Reactor Core ◽  
Heat Removal ◽  
The Core ◽  
Computational Fluid Dynamics Cfd ◽  
Heat Removal System ◽  
China Experimental Fast Reactor ◽  
Full Core

As the first developmental step of the sodium-cooled fast reactor (SFR) in China, the pool-type China Experimental Fast Reactor (CEFR) is equipped with the openings and inter-wrapper space in the core, which act as an important part of the decay heat removal system. The accurate prediction of coolant flow in the reactor core calls for complete three-dimensional calculations. In the present study, an investigation of thermal-hydraulic behaviors in a 180° full core model similar to that of CEFR was carried out using commercial Computational Fluid Dynamics (CFD) software. The actual geometries of the peripheral core baffle, fluid channels and narrow inter-wrapper gap were built up, and numerous subassemblies (SAs) were modeled as the porous medium with appropriate resistance and radial power distribution. First, the three-dimensional flow and temperature distributions in the full core under normal operating condition are obtained and quantitatively analyzed. And then the effect of inter-wrapper flow (IWF) on heat transfer performance is evaluated. In addition, the detailed flow path and direction in local inter-wrapper space including the internal and outlet regions are captured. This work can provide some valuable understanding of the core thermal-hydraulic phenomena for the research and design of SFRs.

Fast Reactor Core Seismic Experiment and Analysis Under Strong Excitation

2018 ◽  
Author(s):  
Tomohiko Yamamoto ◽  
Akihisa Iwasaki ◽  
Kazuteru Kawamura ◽  
Shinichiro Matsubara ◽  
Hidenori Harada
Keyword(s):  
Fast Reactor ◽  
Structural Integrity ◽  
Seismic Analysis ◽  
Reactor Core ◽  
Vertical Displacement ◽  
Three Dimensions ◽  
Analysis Model ◽  
Core Element ◽  
Seismic Experiment ◽  
Strong Excitation

In design of fast reactor (FR) core components, seismic response must be evaluated in order to ensure the structural integrity. Thus, a core seismic analysis method has been developed to evaluate 3D core vibration behavior considering fluid structure interaction and vertical displacement (upward). Thirty seven 1/1.5 scale core element models which shape hexagonal-arrangement were used to validate the core element vibration analysis code in three dimensions (REVIAN-3D). Based on the test data, the newly incorporated analysis model has been verified to respond to strong excitation.

Core Seismic Experiment and Analysis of a Large Number of Element Models for Fast Reactor

2017 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Shinichiro Matsubara ◽  
Tomohiko Yamamoto ◽  
Seiji Kitamura ◽  
Shigeki Okamura
Keyword(s):  
Fast Reactor ◽  
Structural Integrity ◽  
Impact Force ◽  
Seismic Analysis ◽  
Reactor Core ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Three Dimensions ◽  
Core Element ◽  
Core Components

To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Generally, the fast reactor core is made of several hundred core elements in hexagonal arrangement. When a big earthquake occurs, large horizontal displacement, vertical displacement (rising) and impact force of each core element may cause a trouble for control rod insertability, reactivity insertion and core element intensity. Therefore, a seismic analysis method of a fast reactor core considering three-dimensional nonlinear behavior, such as bouncing, impact, fluid-structure interaction, etc. was developed. Validation of the core element vibration analysis code in three dimensions (REVIAN-3D) was conducted by 1/1.5 scale 32 core element mock-ups one-row test and 1/2.5 scale 313 core element mock-ups hexagonal-matrix test. In this verification, the applicability of the result obtained on a single model test or a small number of scale tests is verified when the number of core components increases. The vertical behavior (rising displacement) and horizontal behavior (Impact force, horizontal response) as a single core element of the analysis result agreed very well with the experiments.

Calculation studies of coated particles performance in sodium-cooled fast reactor

Kerntechnik ◽  
2021 ◽  
Vol 86 (1) ◽  
pp. 45-49
Author(s):  
N. V. Maslov ◽  
E. I. Grishanin ◽  
P. N. Alekseev
Keyword(s):  
Fast Reactor ◽  
Reactor Core ◽  
Heat Removal ◽  
Design Solution ◽  
Fast Neutrons ◽  
Steel Shell ◽  
Primary Circuit ◽  
Coated Particles ◽  
The Core ◽  
Fuel Assemblies

Abstract This paper presents results of calculation studies of the viability of coated particles in the conditions of the reactor core on fast neutrons with sodium cooling, justifying the development of the concept of the reactor BN with microspherical fuel. Traditional rod fuel assemblies with pellet MOX fuel in the core of a fast sodium reactor are directly replaced by fuel assemblies with micro-spherical mixed (U,Pu)C-fuel. Due to the fact that the micro-spherical (U, Pu)C fuel has a developed heat removal surface and that the design solution for the fuel assembly with coated particles is horizontal cooling of the microspherical fuel, the core has additional possibilities of increasing inherent (passive) safety and improve the competitiveness of BN type of reactors. It is obvious from obtained results that the microspherical (U, Pu)C fuel is limited with the maximal burn-up depth of ∼11% of heavy atoms in conditions of the sodium-cooled fast reactor core at the conservative approach; it gives the possibility of reaching stated thermal-hydraulic and neutron-physical characteristics. Such a tolerant fuel makes it less likely that fission products will enter the primary circuit in case of accidents with loss of coolant and the introduction of positive reactivity, since the coating of microspherical fuel withstands higher temperatures than the steel shell of traditional rod-type fuel elements.

Structural Confinement and Safety Design of a Fast Reactor Core

1981 ◽  
Vol 103 (2) ◽  
pp. 289-294
Author(s):  
F. D. Ju ◽  
J. G. Bennett
Keyword(s):  
Fast Reactor ◽  
Lateral Pressure ◽  
Numerical Solutions ◽  
Homogeneous Medium ◽  
Safety Margin ◽  
Reactor Core ◽  
Gas Pressure ◽  
Equivalent Stiffness ◽  
Friction Forces ◽  
The Core

In certain fast-reactor designs, the core is an assemblage of a large number of containers of long, hexagonal, hollow cylinders mounted vertically. These so-called “hex-cans” sit individually on coolant nozzles held down by their own weight, and are held as a group laterally at two levels by two constraint rings. At operating temperature, the rings bear on the hex-can assembly because of differences in thermal expansion. The compression of the rings on the hex-can assembly serves to prevent lifting of the can individually or in groups because of any accidental buildup of gas pressure. In the analysis, it is observed that the large number of hexcans and the distribution of the temperature field are such that the cross section of the reactor core can be treated as in a locally uniform dilatational field. An approximate equation was developed relating the plane deformation of a hollow hex cylinder to the global lateral pressure. The parameters are the material constitution and the thickness index (the ratio of the interior and the exterior cross-flat dimensions). The effective range of the equation covers the thickness ratio from zero to the stability limit when the wall becomes too thin resulting in buckling under the lateral pressure. The design equation is exact for zero thickness index. For hollow hex cylinders, numerical solutions were also obtained by the finite element method as a comparison. For a thickness index of 0.9 to 0.95, the difference is less than 0.1 percent. The cylinder constitutive equation is then used to determine an equivalent stiffness for a solid hex cylinder that is to have the same deformation as the given hex-can. The entire planar core region is then analyzed as a homogeneous medium of the equivalent stiffness. The method was applied to the core confinement design for a fast reactor. The thermoelastic solution was then applied to a relatively simpler configuration than the actual case to give a measure of the lateral pressure. The available friction forces for various lift configurations were then obtained. The gas pressure necessary to overcome the minimum friction force thus resulted. In addition, using the lateral pressure, the safety margin of the wall thickness of the hex-can for stability failures was determined.

The Seismic Dynamic Response on the Steel Spatial Arch Truss with 60 m Span and 0.4 Rise-Span Ratio

2011 ◽  
Vol 368-373 ◽  
pp. 850-853
Author(s):  
Hai Wang Li ◽  
Jing Jing Guo ◽  
Jing Liu
Keyword(s):  
Plastic Hinge ◽  
Vertical Direction ◽  
Nonlinear Effects ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Dynamic Responses ◽  
Peak Acceleration ◽  
Displacement Ductility ◽  
Earthquake Action ◽  
Material Nonlinear

In this paper, the elasto-plastic dynamic analysis on the steel spatial arch truss with 60 m span and 0.4 rise-span ratio is carried out under earthquake wave with SAP2000. In the analyses, the geometric and material nonlinear effects are considered at the same time based on the plastic-hinge theory. Under the action of EL wave with the peak increasing gradually, its elasto-plastic dynamic responses have been obtained. The results show that its failure mode under the earthquake action is elasto-plastic dynamic buckling; that its critical peak acceleration of EL earthquake wave when applied in horizontal direction is 808.5 gal, and is 789.0 gal when applied in vertical direction; The ratio of its maximal node horizontal displacement and its structural height is 1/259, and its displacement ductility coefficient is 1.071; The ratio of its maximal node vertical displacement and its structural span is 1/736, and its displacement ductility coefficient is 1.105.

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