The Reliability Prediction of HTR’s Graphite Component in Various Temperature and Neutron Dose Levels

2013 ◽  
Author(s):  
Xiang Fang ◽  
Haitao Wang ◽  
Xingtuan Yang ◽  
Suyuan Yu
Keyword(s):  
High Temperature ◽  
Neutron Irradiation ◽  
Three Dimensional ◽  
Reactor Core ◽  
Neutron Dose ◽  
Element Analysis ◽  
The Core ◽  
Three Dimensional Finite Element ◽  
Dose Levels ◽  
The Impact

In high temperature gas-cooled reactors (HTRs), graphite is used as the main structure material. The side reflecter of the reactor core is composed by a pile of graphite bricks. In real operational condition of the reactor, both high temperature and fast neutron irradiation have great effect on the behavior of graphite components. The non-uniform distribution of temperature and neutron dose cause obvious stress accumulation, which greatly affects the security and reliability of the graphite components. In addition, high temperature and neutron irradiation make the properties of graphite change in evidence, and the changes are not linear. Such changes must be considered and simulated in the calculation, in order to predict the stress concentration condition and the reliability of the graphite brick correctly. A FORTRAN code based on user subroutines of MSC.MARC is developed in INET in order to perform three-dimensional finite element analysis of irradiated behavior of the graphite components for the HTRs. In this paper, the stress level and failure probability of graphite components are calculated and obtained under different in-core temperatures and neutron dose levels of the core side of brick. 400°C, 500°C, 600°C and 700°C are selected as the core side temperature, while the range of neutron dose is 0 to 1022n cm-2 (EDN). Different constitutive laws are used in stress analysis procedure. The impact of different temperature and neutron dose levels are discussed.

A High Temperature, Fast Switching SiC Multi-chip Power Module (MCPM) for High Frequency (> 500 kHz) Power Conversion Applications

2013 ◽  
Vol 2013 (HITEN) ◽  
pp. 000056-000060 ◽  
Author(s):  
Z. Cole ◽  
B. S. Passmore ◽  
B. Whitaker ◽  
A. Barkley ◽  
T. McNutt ◽  
...  
Keyword(s):  
High Temperature ◽  
High Frequency ◽  
Power Conversion ◽  
Three Dimensional ◽  
Boost Converter ◽  
Switching Frequency ◽  
Power Module ◽  
Element Analysis ◽  
Switching Characteristics ◽  
Three Dimensional Finite Element

In high frequency power conversion applications, the dominant mechanism attributed to power loss is the turn-on and -off transition times. To this end, a full-bridge silicon carbide (SiC) multi-chip power module (MCPM) was designed to minimize parasitics in order to reduce over-voltage/current spikes as well as resistance in the power path. The MCPM was designed and packaged using high temperature (> 200 °C) materials and processes. Using these advanced packaging materials and devices, the SiC MCPM was designed to exhibit low thermal resistance which was modeled using three-dimensional finite-element analysis and experimentally verified to be 0.18 °C/W. A good agreement between the model and experiment was achieved. MCPMs were assembled and the gate leakage, drain leakage, on-state characteristics, and on-resistance were measured over temperature. To verify low parasitic design, the SiC MCPM was inserted into a boost converter configuration and the switching characteristics were investigated. Extremely low rise and fall times of 16.1 and 7.5 ns were observed, respectively. The boost converter demonstrated an efficiency of > 98.6% at 4.8 kW operating at a switching frequency of 250 kHz. In addition, a peak efficiency of 96.5% was achieved for a switching frequency of 1.2 MHz and output power of 3 kW.

Fire Durations of Concern for a Modern Legal Weight Truck Cask

2006 ◽  
Author(s):  
Neelima Mallidi ◽  
Miles Greiner ◽  
Venkata V. R. Venigalla
Keyword(s):  
Thermal Protection ◽  
Three Dimensional ◽  
Time History ◽  
Element Analysis ◽  
Pressurized Water ◽  
Dimensional Finite Element ◽  
Term Creep ◽  
Three Dimensional Finite Element ◽  
The Impact ◽  
Containment Integrity

The response of a truck package designed to transport four pressurized water reactor fuel assemblies to a simplified radiation fire model is simulated for a range of fire durations using three-dimensional finite element analysis. A model is developed to determine the cumulative seal degradation from its temperature versus time history. This model is used to determine the minimum fire duration that causes the seal to lose containment integrity. The fire durations that cause the maximum cladding temperature to reach its long term creep deformation and burst rupture temperatures are determined and found to be longer than the duration that cause the seal to lose containment integrity. These simulations are repeated for package models without the compliant regions of the impact limiters, and for a package with the impact limiter completely removed. These simulations quantify the level of thermal protection the impact limiters provide to the seals and cladding during simulated fires.

Comparison of Stress Distribution in Surrounding Bone during Insertion of Dental Implants on Four Implant Threads under the Effect of an Impact: A Finite Element Study

2022 ◽  
Vol 54 ◽  
pp. 89-101
Author(s):  
Noureddine Djebbar ◽  
Abdessamed Bachiri ◽  
Benali Boutabout
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Load Transfer ◽  
Three Dimensional ◽  
Primary Stability ◽  
Implant Design ◽  
Element Analysis ◽  
Three Dimensional Finite Element ◽  
The Impact ◽  
Surrounding Bone

The design of an implant thread plays a fundamental role in the osseointegration process, particularly in low-density bone. It has been postulated that design features that maximize the surface area available for contact may improve mechanical anchorage and stability in cancellous bone. The primary stability of a dental implant is determined by the mechanical engagement between the implant and bone at the time of implant insertion. The contact area of implant-bone interfaces and the concentrated stresses on the marginal bones are principal concerns of implant designers. Numerous factors influence load transfer at the bone-implant interface, for example, the type of loading, surface structure, amount of surrounding bone, material properties of the implant and implant design. The purpose of this study was to investigate the effects of the impact two different projectile of implant threads on stress distribution in the jawbone using three-dimensional finite element analysis.

Dynamic Response of the Human Head to Impact by Three-Dimensional Finite Element Analysis

1994 ◽  
Vol 116 (1) ◽  
pp. 44-50 ◽  
Author(s):  
J. S. Ruan ◽  
T. Khalil ◽  
A. I. King
Keyword(s):  
Finite Element ◽  
Fluid Layer ◽  
Three Dimensional ◽  
Human Head ◽  
Frontal Impact ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
The Impact ◽  
The Brain

The impact response of the human head has been determined by three-dimensional finite element modeling. This model represents the essential features of a 50th percentile human head. It includes a layered shell closely representing the cranial bones with the interior contents occupied by an inviscid continuum to simulate the brain. A thin fluid layer was included to represent the cerebral-spinal fluid. To validate the model, its response was obtained by applying a sine-squared pulse of 6.8 kN in magnitude and 10 ms in duration. The load was applied to a freely supported head on the frontal bone in the midsagittal plane. The computed pressure-time histories at 5 locations within the brain material compared quite favorably with previously published experimental data from cadaver experiments and provided a reasonable level of confidence in the validation of the model. A parametric study was subsequently conducted to identify the model response when the impact site (frontal, side, occipital) and the material properties of the head were varied. Interestingly, the model predicted higher contre-coup pressure in the frontal lobe (from occipital impact) than that predicted in the occipital region from frontal impact. This finding supports clinical findings of contre-coup injury being more likely to result from occipital impact than from frontal impact.

Finite Element Analysis and Stress Intensification Factor Determination for Core to Jacket Joints

2009 ◽  
Author(s):  
Pishdad Mohammadi-Araz
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Stress Analysis ◽  
Three Dimensional ◽  
Piping System ◽  
Beam Model ◽  
Element Analysis ◽  
The Core ◽  
Stress Intensification Factor ◽  
Three Dimensional Finite Element

In this study Stress Intensification Factor (“SIF”) and stress analysis for core to jacket joints are investigated. The three-dimensional finite element shell model consists of two shells: the jacket and the core. The effect of the welded joint discontinuity is taken into account by applying a stress concentration factor. It is presumed that the core and shell are ASTM A-106 GR B [1]. The joint is modeled for different pipe-outside diameters and wall-thicknesses and SIF is calculated for different Head shapes, which are discussed further in this paper. The model is examined with different mesh types and the results are discussed. Temperature gradient in pipe wall-thickness causes thermal stress. The thermal stress, combined with operating, sustained and differential expansion stress are considered in the stress analysis of core and jacket shell. The results for different temperature gradients are compared. The imposed displacement loads caused by global temperature difference between core and the jacket are taken from a beam model run of a typical discontinuous steam jacketed piping system.

Parameters Setting Impact Analysis of Composite Cockpit Finite Element Analysis Based on Properties of Composite Materials

2013 ◽  
Vol 738 ◽  
pp. 103-106
Author(s):  
Hai Peng Gao ◽  
Meng Liu ◽  
Jun Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Analysis ◽  
Three Dimensional ◽  
Single Layer ◽  
Uncertain Parameters ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
The Impact

At present, mechanics properties of composite at home and abroad only include data of the single-layer board. On the basis of researching literature of composite finite element analysis, approaches of setting composite three-dimensional parameters based on the parameters of single-layer material are summarized. By three-dimensional finite element analysis on composite whole cockpit, the impact of uncertain parameters on cockpit analysis results is studied. Adopting maximum stress criteria, maximum strain criteria and Tsai-Wu criteria to evaluate the initial failure of composite whole cockpit, the impact of material uncertain parameters on initial breaking strength prediction of cockpit is studied. The study can provide reference for three-dimensional finite element analysis of composite whole cockpit.

Effect of In-Core Temperature on the Life Evaluation of Graphite Component

2009 ◽  
Author(s):  
Xiang Fang ◽  
Suyuan Yu ◽  
Haitao Wang
Keyword(s):  
Fast Neutron ◽  
Core Temperature ◽  
Three Dimensional ◽  
Reactor Core ◽  
Vertical Direction ◽  
Constitutive Law ◽  
Fast Neutrons ◽  
Element Analysis ◽  
Temperature Levels ◽  
The Impact

Graphite is widely used as a major internal structural material in high temperature gas-cooled reactors (HTRs). In order to evaluate service lives of graphite components, both the fast neutrons and temperature distributions inside the reactor core are required as input data for the irradiation-induced stress analysis. Since the fast neutron distributions may vary along the vertical direction due to the movement of the control rods, the corresponding location of the maximum neutron fluence changes with different in-core temperature levels. In this paper, the effect of the in-core temperature on both the stresses of graphite components due to irradiation and the corresponding life evaluations are studied numerically. The associated constitutive law for the simulation of irradiated graphite covering properties, dimensional changes and creep is briefly reviewed. A FORTRAN code based on user subroutines of MSC.MARC is developed in INET in order to perform three-dimensional finite element analysis of irradiated behavior of the graphite components for the HTRs. A side reflector graphite model is established and analyzed under a prescribed fast neutron distribution and several temperature levels. The results of irradiation-induced stresses and failure probability of the side reflector are obtained and the impact of temperature levels is discussed.

Research on the Factors Affect the Settlement of Soft Pile in Double-Layered Foundation

2010 ◽  
Vol 163-167 ◽  
pp. 4512-4519
Author(s):  
Shi Min Zhang ◽  
Kai Yu ◽  
Zhi Ding ◽  
Hao Miao Yang
Keyword(s):  
Elastic Modulus ◽  
Elasticity Modulus ◽  
Three Dimensional ◽  
Vertical Load ◽  
Preferential Treatment ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Pile Settlement ◽  
Three Dimensional Finite Element ◽  
The Impact

The pile work on the complex properties of three-dimensional finite element analysis has been made by building-up one 4x4 soft pole. Having studied on the factors which affect the flexibility pole compound foundation settlement factor in foundation, include the level of vertical load, elastic modulus of the pile, cushion thickness and elastic modulus. The results show that: the impact of soft pile settlement of the factors, the level of vertical load and pile elastic modulus greater impact cushion modulus of elasticity and thickness of the less affected. As for the pole body elasticity modulus and the bed course elasticity modulus, the compound foundation existence is controlled give value preferential treatment most subsides, the bed courses among them almost can be ignored since effect is less.

scholarly journals Understanding the impact of train run-throughs on railway switches using finite element analysis

2018 ◽  
Vol 233 (4) ◽  
pp. 359-369 ◽  
Author(s):  
JY Shih ◽  
H Hemida ◽  
E Stewart ◽  
C Roberts
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Designed Experiment ◽  
Explicit Analysis ◽  
Three Dimensional Finite Element ◽  
Failure Location ◽  
The Impact

Train run-throughs on railway switches is a special issue, where a train passes through non-trailable railway switches in the wrong direction. This has the potential to cause severe damage and can lead to derailment. In order to understand the impact of train run-throughs on railway switches, a three-dimensional finite element model using explicit analysis has been developed. A detailed switch model has been developed that includes all key components: stretcher bars, supplementary drive and point operating equipment. The model was validated through a specifically designed experiment where switch run-throughs were emulated on a real switch; a good agreement was found between the experimental data and the model. The model has been used to make an assessment of the locking mechanisms. The forces in each component have been assessed and investigated, and the observations of failure location and component during run-through analysis are indicated. During a run-through, the supplementary drive rod and stretcher bar encounter a significant plastic deformation, and it is recommended that they should be redesigned in order to avoid plastic behaviour.

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