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.

Core Seismic Experiment and Analysis of Full Scale Single Model for Fast Reactor

2017 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Shinichiro Matsubara ◽  
Tomohiko Yamamoto ◽  
Seiji Kitamura ◽  
Hidenori Harada
Keyword(s):  
Fast Reactor ◽  
Structural Integrity ◽  
Impact Force ◽  
Seismic Analysis ◽  
Reactor Core ◽  
Horizontal Displacement ◽  
Full Scale ◽  
Three Dimensions ◽  
Scale Model ◽  
Core Element

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 (raising) 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. This paper presents a validation of the core element vibration analysis code in three dimensions (REVIAN-3D) for a full scale model. In this validation, 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.

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]

Core Seismic Experiment and Analysis of Hexagonal Bundle Model for Fast Reactor

2017 ◽  
Author(s):  
Akihisa Iwasaki ◽  
Shinichiro Matsubara ◽  
Tomohiko Yamamoto ◽  
Seiji Kitamura ◽  
Shigeki Okamura
Keyword(s):  
Seismic Response ◽  
Fast Reactor ◽  
Impact Force ◽  
Seismic Analysis ◽  
Reactor Core ◽  
Three Dimensions ◽  
Analysis Method ◽  
Core Element ◽  
Core Elements ◽  
Advanced Analysis

To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Therefore, advanced analysis method must be developed to calculate seismic response of a fast reactor core. The fast reactor core is generally made of several hundred core elements which are hexagonal flexible beams embedded at the lower support plate 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 and core element intensity. Therefore, a seismic analysis method of a fast reactor core considering three-dimensional nonlinear behavior, such as impact, fluid-structure interaction, was developed. 1/1.5 scale 37 core element mock-ups hexagonal-matrix experiment was performed to validate the core elements vibration analysis code in three dimensions (REVIAN-3D). Vertical behavior (rising displacement) and horizontal behavior (impact force) were good agreement with experiments by the validation of REVIAN-3D.

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.

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.

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.

Seismic Analysis of Lead-Bismuth-Cooled Fast Reactor Vessel

2013 ◽  
Author(s):  
Juan Ma ◽  
Mei Huang
Keyword(s):  
Fast Reactor ◽  
Structural Integrity ◽  
Seismic Analysis ◽  
Time History ◽  
Hydrodynamic Pressure ◽  
Seismic Loading ◽  
Reactor Vessel ◽  
Analysis Model ◽  
Element Analysis ◽  
Set Up

This paper is aimed at analyzing the structural responses of a Generation IV heavy-liquid-metal-cooled reactor (lead-bismuth-cooled fast reactor) vessel in the event of earthquake. For a seismic design, the seismic time history response analyses are carried out for both a top support type and a bottom support type. It is found that the bottom support type exhibits the better performance. There is the gap between the reactor vessel and guard vessel being filled with [1] argon. It is indispensable to add bellows at vessel upper end for a bottom support type to achieve the connection and seal between the reactor vessel and guard vessel. This paper is the first attempt to evaluate the effects on structural seismic performance by adopting the equivalent springs to simulate this elastic connection. For a seismic investigation, there is a key issue that should be focused on, namely: the fluid-structure interaction due to seismic loading. The vessel is filled with a high-density fluid and might lead to severe hydrodynamic pressure significantly in the occurrence of earthquake. It will impair the structural integrity of reactor vessel. In order to study the structure effects of reactor vessel under seismic loading, an appropriate 3-D finite element analysis model has to be set up and the FEM code ANSYS has been implemented.

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.

A Safety Evaluation of HTTR Core Components Against 2011 Tohoku Earthquake

2013 ◽  
Author(s):  
Kazuhiko Iigaki ◽  
Masato Ono ◽  
Yosuke Shimazaki ◽  
Daisuke Tochio ◽  
Atsushi Shimizu ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Seismic Analysis ◽  
Reactor Core ◽  
Safety Evaluation ◽  
Tohoku Earthquake ◽  
Reactor Power ◽  
2011 Tohoku Earthquake ◽  
The 2011 Tohoku Earthquake ◽  
Maximum Acceleration ◽  
Core Components

On March 11th, 2011, the 2011 Tohoku Earthquake which is one of the largest earthquakes in japan occurred and the maximum acceleration in observed seismic wave in the HTTR exceeded the design value in a part of input seismic motions. Therefore, a visual inspection, a seismic analysis and a performance confirmation test of facilities were carried out in order to confirm the integrity of facility after the earthquake. The seismic analysis was carried out for the reactor core structures by using the response magnification factor method. As the results of the evaluation, the generated stress in the graphite blocks in the reactor core at the earthquake were well below the allowable values of safety criteria, and thus the structural integrity of the reactor core was confirmed. The integrity of reactor core was also supported by the visual inspections of facilities and the operation without reactor power in cold conditions of HTTR.

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