A Modified Technique for Crack Formation on Nuclear Steam Generator Tubing

2003 ◽  
Author(s):  
T. H. Lee ◽  
Y. J. Oh ◽  
I. S. Hwang ◽  
H. S. Chung ◽  
J. Y. Park
Keyword(s):  
Steam Generator ◽  
Crack Depth ◽  
Three Dimensional ◽  
Potential Drop ◽  
Crack Size ◽  
Monitoring And Control ◽  
Modified Technique ◽  
Element Analysis ◽  
Pressurized Water ◽  
Three Dimensional Finite Element

For the aging management and safety assurance of an operating pressurized water reactor (PWR), the integrity of steam generator (SG) tubes receives increasing attention. Non-destructive examination by eddy current technique (ECT), leak rate measurement and burst pressure evaluation constitute key elements. SG tubes containing cracks with physical and microstructural characteristics similar to those of field-aged tubes are needed for the effort. We explored a radial dent loading method to introduce axial intergranular cracks using sensitized alloy 600 tubes in laboratories as a procedure to generate a library of laboratory degraded tubes (LDT) for ECT qualification. Based on three-dimensional finite element analysis and preliminary experimental work that the method is shown to be more useful than the internal pressurization method for the production of cracks with high aspect ratio. In addition, direct current potential drop (DCPD) method applied with array probes has been developed for use in accurate monitoring and control of crack size and shape. In order to minimize plastic deformation of region containing cracks, it is desired to use the radial dent loading only for shallow crack initiation. Then, subsequent growth of crack depth can be made by internal pressurization method.

scholarly journals A New Technique for Intergranular Crack Formation in Alloy 600 Steam Generator Tubing

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Tae Hyun Lee ◽  
Il Soon Hwang ◽  
Han Sub Chung ◽  
Jang Yul Park
Keyword(s):  
Steam Generator ◽  
Three Dimensional ◽  
Potential Drop ◽  
Crack Size ◽  
Element Analysis ◽  
Current Test ◽  
Dimensional Finite Element ◽  
Integrity Management ◽  
A New Technique ◽  
Three Dimensional Finite Element

For the integrity management of steam generator (SG) tubes, nondestructive evaluation performed using eddy current test (ECT) is necessary in the assessment. The reliability of ECT evaluation is dependent on the accuracy of ECT for various kinds of defects. For basic calibration and qualification of these techniques, cracked SG tube specimens having mechanical and microstructural characteristics of intergranular cracks in the field are needed. To produce libraries of laboratory-degraded SG tubes with intergranular cracks, a radial denting method was explored for generating inside diameter and outside diameter axial cracks by three-dimensional finite element analysis and experimental demonstration. The technique is proven to be applicable for generating axial cracks with long and shallow geometries as opposed to the semicircular cracks typically obtained by the internal-pressurization method. In addition, a direct current potential drop method with array probes was developed for accurate monitoring and controlling of crack size and shape. By these methods, long and shallow intergranular axial cracks more typical of actual degraded SG tubes were successfully produced.

scholarly journals Probabilistic Elastic-plastic Fracture Mechanics Analysis of Propagation of Cracks in Pipes under Internal Pressure

2020 ◽  
Vol 14 (54) ◽  
pp. 202-210
Author(s):  
Belaïd Mechab ◽  
Medjahdi Malika ◽  
Mokadem Salem ◽  
Serier Boualem
Keyword(s):  
Distribution Function ◽  
Internal Pressure ◽  
Structural Reliability ◽  
Mechanical Response ◽  
Crack Depth ◽  
Three Dimensional ◽  
Crack Size ◽  
Elastic Plastic ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This study presents a three dimensional finite element method analysis of semi-elliptical surface cracks in pipes under internal pressure load. In the elastic–plastic case, estimates of the J-integral are presented for various ratios including crack depth to pipe thickness (a/t) and strain hardening index in the (R-O) Ramberg-Osgood (n).  Finally, failure probability is accessed by a statistical analysis for uncertainties in loads and material properties, and structural reliability and crack size. The Monte Carlo method is used to predict the distribution function of the mechanical response. According to the obtained results, we note that the stress variation and the crack size are important factors influencing on the distribution function of (J/Je).

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.

Crake Effect on the Dynamic Characteristics of Elastically Coupled Beams

2011 ◽  
Vol 110-116 ◽  
pp. 328-336
Author(s):  
Samer A. M. Al-Said
Keyword(s):  
Dynamic Characteristics ◽  
Crack Depth ◽  
Three Dimensional ◽  
Model Verification ◽  
Elastic Coupling ◽  
Element Analysis ◽  
Crack Location ◽  
Dimensional Finite Element ◽  
Coupled Beams ◽  
Three Dimensional Finite Element

Simple mathematical model that describes the lateral vibration of elastically coupled cracked cantilever beams carrying rigid disk at their tips is derived. The derived model is used to study the effect of elastic coupling, crack depth and location on the dynamic characteristics of the system. The cracked beam is presented as two beams connected with torsional spring at the crack location. Model verification is carried out using three dimensional finite element analysis using ANSYS program, the verification results showed good agreement with that obtained from the proposed model. The study reveals that the first system natural frequency is affected by the crack and the elastic coupling.

Three-Dimensional Finite Element Analysis of Antisymmetric Four-Point Shear Specimen

2016 ◽  
Author(s):  
Mark Cohen ◽  
Xin Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Depth ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Specimen Thickness ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper, the four-point shear (FPS) specimen is studied for different combinations of crack depth (a/W) and specimen thickness (t/W) to width ratios. Extensive 3D finite element analysis (FEA) has been carried out, and comprehensive solutions of fracture parameters produced. From the results of the finite element analysis, the size of the plastic zone is studied at various points through-thickness. Through these analyses, the effects of considering finite-thickness specimens are illustrated.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

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