Investigative Study of 2-D vs. 3-D Weld Residual Stress Analyses of the NRC Phase II Mockup

2012 ◽  
Author(s):  
Francis H. Ku ◽  
Shu (Stan) S. Tang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Phase Ii ◽  
Three Dimensional ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Approximation Techniques ◽  
Weld Residual Stress ◽  
Axisymmetric Modeling ◽  
Stress Analyses

Finite element weld residual stress analyses are performed to investigate the similarities and differences between two-dimensional (2-D) and three-dimensional (3-D) finite element analyses on weld residual stress predictions of the NRC Phase II Mockup. The Mockup resembles a typical pressurized water reactor (PWR) surge nozzle of 14″ in diameter which includes a dissimilar metal weld (DMW) connecting the safe end and a stainless steel weld (SSW) connecting the surge line piping. The 2-D analysis employs axisymmetric modeling approach, while the 3-D analysis utilizes moving heat source approximation techniques. The results demonstrate the variations in residual stresses among the weld bead start and stop locations. Comparing the 2-D and 3-D residual results against experiment measurements also reveal the limitations inherent to the 2-D analysis, while the 3-D analysis can produce results that are of closer match to experimental measurements.

Simulation of Triaxial Residual Stress Mapping for a Hollow Cylinder

2012 ◽  
Author(s):  
Mitchell D. Olson ◽  
Wilson Wong ◽  
Michael R. Hill
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Nuclear Power ◽  
Complex Geometry ◽  
Cylindrical Body ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Weld Residual Stress ◽  
Novel Method ◽  
Stress Mapping

This paper describes a novel method to determine a two-dimensional map of the triaxial residual stress on a radial-axial plane of interest in a hollow cylindrical body. With the description in hand, we present a simulation to validate the steps of the method. The simulation subject is a welded cylindrical nozzle typical of a nuclear power pressurized water reactor pressurizer; in the weld region, the nozzle inner diameter is roughly 132 mm (5.2 inch) and the wall thickness is roughly 35 mm (1.4 inch). The pressure vessel side of the nozzle is carbon steel (with a thin stainless steel lining), the piping side is austenitic stainless steel, and between the two are weld and buttering deposits of nickel alloy. Weld residual stresses in such nozzles have important effects on crack growth rates in fatigue and stress corrosion cracking, therefore measurements of weld residual stress can help provide inputs for managing aging reactor fleets. Nuclear power plant welds often have large and complex geometry, which has made residual stress measurements difficult, and this work provides a proof of concept for a new experimental technique for measurements on welded nozzles.

scholarly journals Finite Element Based Full-Life Cyclic Stress Analysis of 316 Grade Nuclear Reactor Stainless Steel Under Constant, Variable, and Random Fatigue Loading

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Bipul Barua ◽  
Subhasish Mohanty ◽  
Joseph T. Listwan ◽  
Saurindranath Majumdar ◽  
Krishnamurti Natesan
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Stress Analysis ◽  
Nuclear Reactor ◽  
Three Dimensional ◽  
Fatigue Loading ◽  
Cyclic Stress ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Fatigue Evaluation

Although S∼N curve-based approaches are widely followed for fatigue evaluation of nuclear reactor components and other safety critical structural systems, there is a chance of large uncertainty in estimated fatigue lives. This uncertainty may be reduced by using a more mechanistic approach such as physics based three-dimensional (3D) finite element (FE) methods. In a recent paper (Barua et al., 2018, ASME J. Pressure Vessel Technol., 140(1), p. 011403), a fully mechanistic fatigue modeling approach which is based on time-dependent stress–strain evolution of material over the entire fatigue life was presented. Based on this approach, in this work, FE-based cyclic stress analysis was performed on 316 nuclear grade reactor stainless steel (SS) fatigue specimens, subjected to constant, variable, and random amplitude loading, for their entire fatigue lives. The simulated results are found to be in good agreement with experimental observation. An elastic-plastic analysis of a pressurized water reactor (PWR) surge line (SL) pipe under idealistic fatigue loading condition was performed and compared with experimental results.

Finite Element Cracking Analysis of Nuclear Containment Vessels Under External Impacts

2011 ◽  
Author(s):  
Y. F. Al-Obaid
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Structural Damping ◽  
Pressurized Water Reactor ◽  
Element Analysis ◽  
Pressurized Water ◽  
Nuclear Containment ◽  
Linear Behavior ◽  
Line Elements ◽  
Aircraft Crash

This paper attempts to examine the behavior of nuclear containment vessels under impact loads. Three-dimensional dynamics finite element analysis is proposed. The analysis includes the non-linear behavior of concrete, structural damping and cracking. A combination of solid isoparametric, panel and line elements representing vessel concrete, steel lining, and prestressing tendons or conventional steel, respectively, is suggested. Three-dimensional computer program OBAID is developed which gives time-dependent interactive calculations for stresses, deflections, cracks, reinforcement and suitable wall and dome thicknesses. An existing concrete containment vessels for pressurized water reactor (PWR) is examined under aircraft crash load.

Residual Stress Analyses of a Multi-Pass Girth Weld: 3-D Special Shell Versus Axisymmetric Models

2000 ◽  
Vol 123 (2) ◽  
pp. 207-213 ◽  
Author(s):  
P. Dong
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Wall Thickness ◽  
Stress Component ◽  
Thick Wall ◽  
Hole Drilling ◽  
Thin Wall ◽  
Weld Residual Stress ◽  
Stress Analyses

In this paper, detailed weld residual stress analyses are presented for a typical multi-pass girth weld in Type 316L stainless steel pipe with r/t ratio of 25. Advanced finite element procedures were used to simulate the residual stress development under controlled welding conditions associated with weld mock-ups. Both axisymmetric and 3-D special shell element models were used to reveal local residual stress details and global residual stress characteristics in the girth weld. Residual stress measurements using hole-drilling method were conducted for model validation on the laboratory weld mock-up welds. A good agreement between finite element predictions and experimental measurements were obtained. The major findings include: (a) Axial residual stresses within and near the weld area exhibit a strong bending feature across the pipe wall thickness, while the hoop residual stresses showed a much less variation through the wall thickness. (b) Some periodic variation of the residual stresses is present along the pipe circumference near the weld, particularly for the axial residual stress component. Such a variation tends to become more pronounced in thick wall than in thin wall girth welds. A 3-D model is essential to adequately capture such 3-D features in residual stress distributions. (c) A rapid variation in weld residual stresses can be seen at start/stop positions, where a high magnitude of axial residual stresses is present in both tension and compression.

Two Case Studies in 3-D Residual Stress Prediction for Nuclear Power Applications

2016 ◽  
Author(s):  
Michael L. Benson ◽  
Patrick A. C. Raynaud ◽  
Frederick W. Brust
Keyword(s):  
Residual Stress ◽  
Nuclear Power ◽  
Three Dimensional ◽  
Repair Process ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Weld Residual Stress ◽  
Plant Operations ◽  
Stress Prediction ◽  
Residual Stress Modeling

Residual stress prediction contributes to nuclear safety by enabling engineering estimates of component service lifetimes. Subcritical crack growth mechanisms, in particular, require residual stress assumptions in order to accurately model the degradation phenomena. In many cases encountered in nuclear power plant operations, the component geometry permits two-dimensional (i.e., axisymmetric) modeling. Two recent examples, however, required three-dimensional modeling for a complete understanding of the weld residual stress distribution in the component. This paper describes three-dimensional weld residual stress modeling for two cases: (1) branch connection welds off reactor coolant loop piping and (2) a mockup to demonstrate the effectiveness of the excavate and weld repair process.

Three-Dimensional Finite Element Analysis of Residual Stress in Arteries

2004 ◽  
Vol 32 (2) ◽  
pp. 257-263 ◽  
Author(s):  
M. L. Raghavan ◽  
S. Trivedi ◽  
A. Nagaraj ◽  
D. D. McPherson ◽  
K. B. Chandran
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Prediction of Weld Residual Stress in a Pressurized Water Reactor Pressurizer Surge Nozzle

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Akira Maekawa ◽  
Atsushi Kawahara ◽  
Hisashi Serizawa ◽  
Hidekazu Murakawa
Keyword(s):  
Residual Stress ◽  
Heat Source ◽  
High Speed ◽  
Nuclear Regulatory Commission ◽  
Round Robin ◽  
Welding Residual Stress ◽  
3D Analysis ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

Primary water stress corrosion cracking (PWSCC) phenomenon in dissimilar metal welds is one of the safety issues in ageing pressurized water reactor (PWR) piping systems. It is well known that analysis accuracy of cracking propagation due to PWSCC depends on welding residual stress conditions. The U.S. Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) carried out an international round robin validation program to evaluate and quantify welding residual stress analysis accuracy and uncertainty. In this paper, participation results of the authors in the round robin program were reported. The three-dimensional (3D) analysis based on a fast weld simulation using an iterative substructure method (ISM), was shown to provide accurate results in a high-speed computation. Furthermore, the influence of different heat source models on analysis results was investigated. It was demonstrated that the residual stress and distortion calculated using the moving heat source model were more accurate.

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