Development of a New Spacer Grid Form to Enhance the Integrity of Fuel Rod Support and the Crush Strength of a Spacer Grid Assembly

2009 ◽  
Author(s):  
Kee-nam Song ◽  
Soo-bum Lee ◽  
Moon-Kyun Shin ◽  
Jae-Jun Lee ◽  
Gyung-Jin Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Area ◽  
Optimization Technique ◽  
Spacer Grid ◽  
Element Analysis ◽  
Fuel Rods ◽  
Fuel Rod ◽  
Design Variables ◽  
Crush Strength

A spacer grid is one of the most important structural components in a LWR fuel assembly. The spacer grid, which supports nuclear fuel rods laterally and vertically with a friction grip, is an interconnected array of slotted grid straps welded at the intersections to form an egg-crate structure. Dimples and springs are stamped into each grid strap to support the fuel rods. The form of grid straps and spring form is known to be closely related with the crush strength of spacer grid assembly and the integrity of fuel rod support, respectively. Zircaloy is prevailing as the material of the spacer grid because of its low neutron absorption characteristic and its successful extensive in-reactor use. The primary considerations are to provide a Zircaloy spacer grid with crush strength sufficient to resist design basis loads especially due to seismic accidents, without significantly increasing pressure drop across the reactor core. Generally, the thickness and height of the Zircaloy grid strap have been the main design variables in order to meet the above considerations. Recently, it was reported that a dimple location is also a design variable that affects the crush strength of a spacer grid assembly. In this study, a new spacer grid form was developed in order to enhance the integrity of the fuel rod support and the crush strength of the spacer grid assembly by using a systematic optimization technique. Finite element analysis and crush strength tests on the developed new spacer grid form were carried out to check the performance enhancement compared to commercial spacer grids. The enhancement of fuel rod support was confirmed by comparisons of contact area, peak stresses, plastic deformation and etc. According to the results, it is estimated that the actual critical load enhancement of the spacer grid assembly is approximately up to 30% and the actual contact area, when a fuel rod inserted into a spacer grid cell, is more than double for the developed new spacer grid form. And also, some design variables that effect the crush strength of a PWR spacer grid assembly were classified and their effects on the crush strength were investigated by a finite element analysis and a crush strength test.

Probabilistic finite element analysis in heat transfer to a nuclear fuel rod bumper support

2004 ◽  
Vol 218 (12) ◽  
pp. 1499-1505
Author(s):  
Rama Subba Reddy Gorla
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Nuclear Fuel ◽  
Cost Effective ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Element Analysis ◽  
Transfer Rates ◽  
Fuel Rod ◽  
Design Variables

Heat transfer from a nuclear fuel rod bumper support was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall heat transfer rates due to the thermodynamic random variables. These results can be used to identify quickly the most critical design variables in order to optimize the design and to make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in heat transfer and to the identification of both the most critical measurements and the parameters.

Enhanced Vibration Control of Ultrasonic Tooling Using Finite Element Analysis

1991 ◽  
Author(s):  
Kevin O’Shea
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Sections ◽  
High Frequency ◽  
Excellent Correlation ◽  
Accurate Identification ◽  
Element Analysis ◽  
Optimum Configuration ◽  
Slot Length ◽  
Design Variables

Abstract The use of finite element analysis (FEA) in high frequency (20–40 kHz), high power ultrasonics to date has been limited. Of paramount importance to the performance of ultrasonic tooling (horns) is the accurate identification of pertinent modeshapes and frequencies. Ideally, the ultrasonic horn will vibrate in a purely axial mode with a uniform amplitude of vibration. However, spurious resonances can couple with this fundamental resonance and alter the axial vibration. This effect becomes more pronounced for ultrasonic tools with larger cross-sections. The current study examines a 4.5″ × 6″ cross-section titanium horn which is designed to resonate axially at 20 kHz. Modeshapes and frequencies from 17–23 kHz are examined experimentally and using finite element analysis. The effect of design variables — slot length, slot width, and number of slots — on modeshapes and frequency spacing is shown. An optimum configuration based on the finite element results is prescribed. The computed results are compared with actual prototype data. Excellent correlation between analytical and experimental data is found.

Development and Analysis for a New Compliant XY Micropositioning Stage Applied for Nanoindentation Tester System

2019 ◽  
Vol 894 ◽  
pp. 60-71
Author(s):  
Minh Phung Dang ◽  
Thanh Phong Dao ◽  
Hieu Giang Le ◽  
Ngoc Thoai Tran
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Taguchi Method ◽  
Optimization Problems ◽  
High Reliability ◽  
Hybrid Approach ◽  
Element Analysis ◽  
Amplification Ratio ◽  
Design Variables ◽  
The Finite Element Analysis

A Compliant XY micropositioning stage is purported for situating a material sample in nanoindentation tester process. This paper aims to develop, analyze and optimize a XY compliant micropositioning stage. The working stroke of proposed XY stage is amplified by combining the four-lever and a bridge amplification mechanism. To enhance the performances of the stage, the main geometric parameters are optimized by an integration method of Taguchi method, response surface method (RSM) and genetic algorithm (GA). Firstly, static analysis and dynamic analysis are conducted by the finite element analysis in order to predict initial performances of the XY stage. Secondly, the number of experiments and the data are retrieved by combination of the finite element analysis-integrated Taguchi method. Thirdly, the effects of main design variables on the output response sensitivity are considered. Later on, mathematical model for the amplification ratio was established by the RSM. Finally, based on the mathematical equation, the GA is adopted to define the optimal design variables. The results of numerical validations are in a good agreement with the predicted results. The results depicted that the proposed hybrid approach ensures a high reliability for engineering optimization problems.

The Main Effect of Design Variables for a Safety Valve on a Fracture Pressure

2007 ◽  
Vol 345-346 ◽  
pp. 1581-1584
Author(s):  
Sang Woo Lee ◽  
Dae Young Shin ◽  
Kyoung Jin Chun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thin Plate ◽  
Safety Valve ◽  
Analysis Method ◽  
Element Analysis ◽  
Finite Element Analysis Method ◽  
Fracture Pressure ◽  
Design Variables ◽  
Circular Thin Plate

The safety valve has been designed to protect high pressure vessels. A fracture plate made of a circular thin plate is located within the safety valve. The circular thin plate has an outlet for fluid release and to help decrease the pressure. As such, fracture of the circular thin plate can occur at the appointed pressure. In this study, design variables of the safety valve were used to control fracture pressure so that it was easy to apply in the development of a new model of a safety valve. Design variables were fluid diameter of the safety valve, thickness of the fracture plate, filet radius of the clamping bolt, fracture pressure, and clamped torque of the clamping bolt. Design variables were selected, since the fracture experiment indicated that these variables might play a critical role in the fracture of the circular thin plate. Fracture pressure was calculated by the finite element analysis method and analyzed to affect the design variables on the fracture pressure. Using regression analysis, main design variables such as the fluid diameter, the thickness and the fillet were selected and the relationships of the variables were expressed by a regression equation. Furthermore, finite element analysis method and the regression equation were verified comparing with the experiment result.

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