Finite Element Welding Residual Stress Analysis of CRDM Penetration Nozzles

2021 ◽  
Vol 144 (1) ◽  
Author(s):  
Seung-Jae Kim ◽  
Eui-Kyun Park ◽  
Hong-Yeol Bae ◽  
Ju-Hee Kim ◽  
Nam-Su Huh ◽  
...  
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Reactor Vessel ◽  
Welding Residual Stress ◽  
Alloy 600 ◽  
Stress Distributions ◽  
Control Rod ◽  
Residual Stress Analysis

Abstract This article investigates numerically welding residual stress distributions of a tube with J-groove weld in control rod drive mechanisms of a pressurized nuclear reactor vessel. Parametric study is performed for the effect of the tube location, tube dimensions, and material's yield strength. It is found that residual stresses increase with increasing the inclination angle of the tube, and the up-hill side is the most critical. For thicker tube, residual stresses decrease. For material's yield strength, both axial and hoop residual stresses tend to increase with increasing the yield strength of Alloy 600. Furthermore, axial stresses tend to increase with increasing yield strength of Alloys 82/182.

Comparison of Welding Residual Stress Solutions for Control Rod Drive Mechanism Nozzles

2007 ◽  
Author(s):  
D. Rudland ◽  
Y. Chen ◽  
T. Zhang ◽  
G. Wilkowski ◽  
J. Broussard ◽  
...  
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Nuclear Regulatory Commission ◽  
Welding Residual Stress ◽  
Pressurized Water ◽  
Control Rod ◽  
Drive Mechanism ◽  
Time Period ◽  
Regulatory Commission

In the last 7 years, the incidences of cracking in Alloy 600 control rod drive mechanism (CRDM) tubes and their associated welds have increased significantly. The cracking mechanism has been attributed to pressurized water stress corrosion cracking (PWSCC) and has been shown to be driven by welding residual stresses and operational stresses in the weld region. During this time period, both the industry and the US Nuclear Regulatory Commission have been conducting detailed welding simulation analyses to predict the magnitude of these stresses in both the weld and tube material. To this point, a direct comparison of these analysis methodologies and results has not been made. In this paper, weld residual stress results from U.S. industry (conducted by Dominion Engineering) and the U.S. NRC (conducted by Engineering Mechanics Corporation of Columbus) for a steep angle (53 degrees) CRDM nozzle are compared. This comparison was performed for different yield strength tube materials, however only the low yield strength results are presented in this paper. The comparison illustrates the effect of weld analyses assumptions and suggests that simplifications in the analyses, i.e., lumping weld passes or material property assumptions, may lead to high predicted weld residual stresses.

Experimental and Computational Residual Stress Evaluation of a Weld Clad Plate and Machined Test Specimens

1988 ◽  
Vol 110 (4) ◽  
pp. 297-304 ◽  
Author(s):  
E. F. Rybicki ◽  
J. R. Shadley ◽  
A. S. Sandhu ◽  
R. B. Stonesifer
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Computational Model ◽  
Stress Analysis ◽  
Elevated Temperatures ◽  
Stress Distributions ◽  
Heat Treated ◽  
Residual Stress Analysis ◽  
The Difference ◽  
Set Up

Residual stresses in a heat treated weld clad plate and test specimens obtained from the plate are determined using a combination of experimental residual stress analysis and a finite element computational model. The plate is 102 mm thick and made of A 533-B Class 2 steel with 308 stainless steel cladding. The plate is heated to 538 C and allowed to cool uniformly. Upon cooling, residual stresses are set up in the clad plate because of the difference between the coefficients of thermal expansion of the plate and the cladding. Residual stress in the clad plate is determined using both a previously verified experimental residual stress analysis technique and a computational model. Removing test specimens from the clad plate can relax the stresses in the cladding. Thus, residual stress distributions were also determined for two types of clad test specimens that were removed from the plate. These test specimens were designed to examine the effect of cladding thickness on residual stresses. Good agreement was found between the experimentally obtained residual stress values and the residual stresses calculated from the computational model. Because of the interest in tests conducted at elevated temperatures and the inherent difficulty in doing experimental residual stress analysis at elevated temperatures, the computational model was applied to examine the effect of elevated temperature on the residual stresses in the test specimens. Peak stresses in the heat treated clad plate were found to approach the yield stress of the cladding material. It was also found that removing a 32 mm clad specimen with cladding on one side reduced the residual stresses in the cladding. However, the residual stresses in the cladding were found to increase when one-half of the cladding thickness was machined away to form the second test specimen geometry. Residual stresses parallel and perpendicular to the weld direction were very similar in magnitude for all cases considered. The effect that heating the test specimens to 204 C has on residual stress distributions was to reduce the residual stress in the cladding and the plate.

Welding Residual Stress Analysis Using Axisymmetric Modeling for Shroud Support Structure

2008 ◽  
Author(s):  
Kazuo Ogawa ◽  
Yukihiko Okuda ◽  
Toshiyuki Saito ◽  
Takahiro Hayashi ◽  
Rie Sumiya
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Large Scale ◽  
Structural Integrity ◽  
Plastic Material ◽  
Welding Residual Stress ◽  
Stress Distributions ◽  
Surface Residual Stress ◽  
Actual Structure ◽  
Elastic Plastic Material

Recently, several cracks caused by stress corrosion cracking (SCC) have been found on welds of shroud supports in Boiling Water Reactor (BWR) plants. The major cause of SCC in a weld joint is considered due to welding residual stress generated in the fabrication processes of the components. For continuous safety operations, it is necessary to estimate the structural integrity of such shroud supports with cracks based on the distribution of residual stresses induced by welding. In order to know and to validate the numerical method of residual stresses induced by welding of large scale and complex shaped components, a BWR shroud support mock-up with a hemispherical base of reactor pressure vessel (RPV) was fabricated by Japan Nuclear Energy Safety Organization (JNES) as a national project. The mock-up has a 32° section of actual BWR shroud supports with approximately the same configurations, materials and welding conditions of an actual component. During welding in the fabrication process of the mock-up, temperature was measured and after completion of the mock-up fabrication, surface residual stress distributions for each weld were also measured by the sectioning method. In addition, through-thickness residual stress distributions were investigated. Residual stress for each weld was calculated by using axisymmetric models considering temperature dependent elastic-plastic material properties. Though the actual structure of shroud supports is essentially complex, we simplified axisymmetric models in the center of the cross section. The analysis results show a similar profile and good agreement with the measured results on the surface of all the welds and through the welds at the upper and lower joints of the shroud support leg.

scholarly journals Finite Element Prediction of Residual Stress Distributions in a Multipass Welded Piping Branch Junction

2006 ◽  
Author(s):  
Wei Jiang ◽  
Kadda Yahiaoui
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Welding Process ◽  
Pressure Vessels ◽  
Welding Residual Stress ◽  
Stress Distributions ◽  
Multipass Welding ◽  
Hexahedral Elements ◽  
Element Removal

Piping branch junctions and nozzle attachments to main pressure vessels are common engineering components used in the power, oil and gas, and shipbuilding industries amongst others. These components are usually fabricated by multipass welding. The latter process is known to induce residual stresses at the fabrication stage which can have severe adverse effects on the in-service behavior of such critical components. It is thus desirable if the distributions of residual stresses can be predicted well in advance of welding execution. This paper presents a comprehensive study of three dimensional residual stress distributions in a stainless steel tee branch junction during a multipass welding process. A full 3D thermo-mechanical finite element model has been developed for this purpose. A newly developed meshing technique has been used to model the complex intersection areas of the welded junction with all hexahedral elements. Element removal/reactivate technique has been employed to simulate the deposition of filler material. Material, geometry and boundary nonlinearities associated with welding were all taken into account. The analysis results are presented in the form of stress distributions circumferentially along the weldline on both run and branch pipes as well as at the run and branch cross sections. In general, this computational model is capable of predicting 3D through thickness welding residual stress, which can be valuable for structural integrity assessments of complex welded geometries.

Fast Computational Residual Stress Analysis for Welded Pipe Joint Based on Iterative Substructure Method

2011 ◽  
Author(s):  
Akira Maekawa ◽  
Shigeru Takahashi ◽  
Hisashi Serizawa ◽  
Hidekazu Murakawa
Keyword(s):  
Residual Stress ◽  
Stress Analysis ◽  
Computing Time ◽  
Welding Residual Stress ◽  
Stress Distributions ◽  
Element Analysis ◽  
Substructure Method ◽  
Residual Stress Analysis ◽  
Welded Pipe ◽  
Pipe Joint

An efficient and reliable method for welding residual stress analysis is reported in this paper. The analysis method to calculate the residual stress using the iterative substructure method was developed and compared with a conventional one using a commercial finite element analysis code; comparisons were made for the analysis accuracy and the computational speed of the residual stress in a welded pipe joint. The residual stress distributions obtained by the both methods agreed well with each other. Moreover, it was clarified that the developed method could calculate the residual stress in a shorter computing time and could calculate the residual stress distribution much faster with nearly the same accuracy as the conventional method when the size of the welding structure was large.

scholarly journals Finite Element Prediction of Residual Stress Distributions in a Multipass Welded Piping Branch Junction

2006 ◽  
Vol 129 (4) ◽  
pp. 601-608 ◽  
Author(s):  
Wei Jiang ◽  
Kadda Yahiaoui
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Welding Residual Stress ◽  
Stress Distributions ◽  
Multipass Welding ◽  
Hexahedral Elements ◽  
Element Removal

Piping branch junctions and nozzle attachments to main pressure vessels are common engineering components used in the power, oil and gas, and shipbuilding industries amongst others. These components are usually fabricated by multipass welding. The latter process is known to induce residual stresses at the fabrication stage, which can have severe adverse effects on the in-service behavior of such critical components. It is thus desirable if the distributions of residual stresses can be predicted well in advance of welding execution. This paper presents a comprehensive study of three dimensional residual stress distributions in a stainless steel tee branch junction during a multipass welding process. A full three dimensional thermomechanical finite element model has been developed for this purpose. A newly developed meshing technique has been used to model the complex intersection areas of the welded junction with all hexahedral elements. Element removal/reactivate technique has been employed to simulate the deposition of filler material. Material, geometry, and boundary nonlinearities associated with welding were all taken into account. The analysis results are presented in the form of stress distributions circumferentially along the weld line on both run and branch pipes as well as at the run and branch cross sections. In general, this computational model is capable of predicting three dimensional through-thickness welding residual stress, which can be valuable for structural integrity assessments of complex welded geometries.

Measurement of Welding Residual Stress in Reactor Components

2011 ◽  
Author(s):  
Adrian T. DeWald ◽  
Michael R. Hill
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
The United States ◽  
Welding Residual Stress ◽  
Contour Method ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Weld Residual Stress ◽  
Metal Weld

Welding residual stresses can significantly impact the performance of structural components. Tensile residual stresses are of particular concern due to their ability to cause significant degradation to the PWSCC resistance of structural materials. The contour method is a residual stress measurement technique capable of generating two dimensional maps of residual stress, which is particularly useful when applied to welds due to the complex residual stress distributions that generally result. The two-dimensional capability of the contour method enables detailed visualization of complex weld residual stress fields. This data can be used to identify locations and magnitude of tensile residual stress hot-spots. This paper provides a summary of the contour method and presents detailed results of contour method measurements made on the dissimilar metal weld region of pressurizer relief nozzles removed from the cancelled WNP-3 plant in the United States as part of the NRC/EPRI weld residual stress (WRS) program [1].

Measurement of Welding Residual Stress in Dissimilar Metal Welds Using the Contour Method

2011 ◽  
Author(s):  
Adrian T. DeWald ◽  
Michael R. Hill ◽  
Eric Willis
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
The United States ◽  
Welding Residual Stress ◽  
Contour Method ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Dissimilar Metal ◽  
Weld Residual Stress

Welding residual stresses can significantly impact the performance of structural components. Tensile residual stresses are of particular concern due to their ability to cause significant degradation to the PWSCC resistance of structural materials. The contour method is a residual stress measurement technique capable of generating two dimensional maps of residual stress, which is particularly useful when applied to welds due to the complex residual stress distributions that generally result. The two-dimensional capability of the contour method enables detailed visualization of complex weld residual stress fields. This data can be used to identify locations and magnitude of tensile residual stress hot-spots. This paper provides a summary of the contour method and presents detailed results of contour method measurements made on the dissimilar metal weld region of pressurizer relief nozzles removed from the cancelled WNP-3 plant in the United States as part of the NRC/EPRI weld residual stress (WRS) program [1].

scholarly journals Numerical Investigation of Welding Residual Stress Field and its Behaviour under Multiaxial Loading in Tubular Joints

2014 ◽  
Vol 996 ◽  
pp. 788-793
Author(s):  
Kimiya Hemmesi ◽  
Majid Farajian ◽  
Dieter Siegele
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Weld Zone ◽  
Welding Residual Stress ◽  
Multiaxial Loading ◽  
Residual Stress Field ◽  
Tubular Joints ◽  
Welded Structure

The lack of clarities in estimating the residual stress threat to the structural integrity has led to conservative assumptions in the current design of welds. The complexities become more in the case of multiaxial loading of welded structure, considering fracture or fatigue. To what extent the residual stresses influence the performance of a welded structure, depends on how stable they are under service loads. Finite element analyses are used here to describe the development of welding residual stresses in tubular joints and their relaxation under multiaxial loading. It is observed that the effect of the torsion load is more significant than the effect of tension load in releasing of the residual stresses. For pure tensile loading, the relaxation of the residual stresses are negligible as long as the applied load is lower than 50% of the yield strength of the material. For a combined tension-torsion loading of 75% of the yield strength, the residual stresses are almost completely released, and in the weld zone they become compressive.

Prediction of Residual Stress Distribution for RPV CRDM Penetration Nozzles

2012 ◽  
Author(s):  
Hong-Yeol Bae ◽  
Yun-Jae Kim ◽  
Ju-Hee Kim ◽  
Sung-Ho Lee ◽  
Kyoungsoo Lee
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Pressure Vessel ◽  
Reactor Pressure Vessel ◽  
Alloy 600 ◽  
Tube Radius ◽  
Pressurized Water ◽  
Tube Geometry ◽  
Reactor Pressure

In nuclear power plants, RPV (Reactor Pressure Vessel) upper head CRDM (Control Rod Drive Mechanism) penetration tubes has been fabricated J-groove weld geometry. Recently, the incidences of cracking in Alloy 600 CRDM tubes and their associated welds have increased significantly. The cracking mechanism has been attributed to PWSCC (Pressurized Water Stress Corrosion Cracking) and has been shown to be driven by welding residual stresses and operational stresses in the weld region. Weld induced residual stress is main factor for crack growth. Therefore exact estimation of residual stress is important for reliable operating. In this point, we have been conducting detailed welding simulation analyses for Korea Nuclear Reactor Pressure Vessel to predict the magnitude of weld residual stresses in penetration tubes. In the present work, the FE (Finite Element) simulations were conducted to investigate the effects of tube geometry (location and ro/t) and material properties on the residual stresses in the J-groove weld for a different location of CRDM tubes. The variables of tube location included three (center-hole, intermediate and steepest side hill tube) inclination angles (Ψ). And this comparison was performed for different tube geometry (ro/t = 2, 3, 4), different yield strength (σo) of tube. In CRDM tube, when increases in tube inclination angle (Ψ), axial residual stress are gradually increased, but hoop residual stresses are decreased at the nearby weld root. In effect of tube radius and thickness, when the thickness of CRDM tubes increases the residual stresses are gradually decreased at the inner surface of tube. And there is no effect of CRDM tube radius (ro). In effect of plastic properties of Alloy 600 material in CRDM, when yield strength of the tube increases the axial residual stresses decreases but hoop residual stress increases.

Sign in / Sign up

Export Citation Format

Share Document