Incorporation of Materials’ Sensitive Simulation Technique Into the PINTIN-CAM Code for Integrity of Nuclear Piping System

2010 ◽  
Author(s):  
Debashis Datta ◽  
Changheui Jang
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Development Process ◽  
Crack Coalescence ◽  
Individual Growth ◽  
Piping System ◽  
Outlet Nozzle ◽  
Failure Location ◽  
Combined Failure

Previously, the development process of a combined probabilistic fracture mechanics code for nuclear piping system was proposed based on some pre-assigned (by default) crack initiation and crack growth techniques e.g. assumption of preexisting cracks in case of no initiated cracks resulted from either fatigue or stress corrosion crack mechanisms and individual growth of those cracks by fatigue or stress corrosion cracking phenomenon without considering crack coalescence criteria. In one sense this type of approach might produce conservative results. To reduce the undue conservatism, in this version, materials’ sensitive crack initiation and subsequent crack growth of these simulated cracks along with crack coalescence criteria have been given prior importance. The logic behind this revised version of PINTIN-CAM PFM code has been presented and one previously published NUREG benchmark numerical problem has been reinvestigated by the improved features of this code. Based on design condition stress data, a typical PWR RPV outlet nozzle section shows the circumferential and axial through wall crack combined failure probability in the order of about 10−2 and 10−3 respectively. Among individual locations of a RPV ON section, the Inconel part shows relatively highest susceptible failure location followed by SS and LAS locations.

scholarly journals The Application of Reliability-Based Design Factors in Stress Corrosion Cracking Evaluations

2002 ◽  
Author(s):  
Edward Friedman
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Initiation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Initiation Time ◽  
Reliability Based Design ◽  
Design Factors

First-order reliability methodology (FORM) is used to develop reliability-based design factors for deterministic analyses of stress corrosion cracking. The basic elements of FORM as applied to structural reliability problems are reviewed and then employed specifically to stress corrosion cracking evaluations. Failure due to stress corrosion cracking is defined as crack initiation followed by crack growth to a critical depth. The stress corrosion cracking process is thus represented in terms of a crack initiation time model and a crack growth rate model, with the crack growth rate integrated from the initiation time to the time at which the crack grows to its critical depth. Both models are described by log-normal statistical distribution functions. A procedure is developed to evaluate design factors that are applied to the mean values of the crack initiation time and the crack growth rate for specified temperature and stress conditions. The design factors, which depend on the standard deviations of the statistical distributions, are related to a target reliability, which is inversely related to an acceptable probability of failure. The design factors are not fixed, but are evaluated on a case-to-case basis for each application. The use of these design factors in a deterministic analysis assures that the target reliability will be attained and the corresponding acceptable probability of failure will not be exceeded. An example problem illustrates use of this procedure.

Development of Fatigue Crack Growth Prediction Model in Reactor Coolant Environment

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Terushi Ishizawa ◽  
Satoshi Takeda ◽  
Takanori Kitada ◽  
Takao Nakamura ◽  
Masayuki Kamaya
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Strain Range ◽  
Crack Size ◽  
Growth Behavior ◽  
Crack Coalescence ◽  
Reactor Coolant ◽  
Crack Growth Curve ◽  
Fatigue Life Reduction ◽  
The Relationship

In order to conduct effective and rational maintenance activity of components in nuclear power plants, it is proposed to manage fatigue degradation based on crack size corresponding to an extent of cumulative fatigue effect. This study is aimed at developing a prediction model for fatigue crack growth in simulated reactor coolant environment. In order to investigate influence of reactor coolant environment on crack initiation and crack growth, two-step replica observations were conducted for environmental fatigue test specimens (type 316 stainless steel) subjected to three kinds of strain range. Crack initiation, growth, and coalescence were observed in the experiments. It is clarified that crack coalescence is one of the dominant factors causing fatigue life reduction, and fatigue life reduction depends on crack size and distance of two coalescing cracks. Then, a model was developed for predicting statistical crack initiation and growth behavior. The relationship between dispersion of crack initiation life and strain range was approximated by the Weibull model to predict crack initiation. Then, the statistical crack growth was modeled using the relation of crack growth rate and strain intensity factor. Furthermore, the crack coalescence was taken into account to the crack growth prediction considering the distance between two cracks. Finally, the crack growth curve, which is the relationship between crack size and operation period, was derived through Monte Carlo simulation with the developed model. The crack growth behavior and residual life in the simulated reactor coolant environment can be reviewed by the crack growth curve obtained with crack initiation, and the growth model developed was compared with the fatigue test results.

scholarly journals Materials science aspects of stress corrosion cracking of Russian pipelines

2019 ◽  
Vol 121 ◽  
pp. 04014
Author(s):  
M.M. Kantor ◽  
V.V. Sudin ◽  
K.A. Solntsev
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Materials Science ◽  
Corrosion Cracking ◽  
Gas Pipelines ◽  
Diagnostic Features ◽  
Main Pipelines ◽  
Type Of Fracture

The work describes the features of stress corrosion cracking (SCC) on Russian gas pipelines. The influence of metal parameters of pipelines on the propagation of SCC is described. The main diagnostic features of SCC used for identification of this type of fracture, the stages of crack growth and the effect of microstructural metal parameters on their propagation are described. Accounting methods for main features crack initiation and growth in order to improve the resistance of the main pipelines metal to SCC are proposed

The Benefit of Hydrogen Addition to the Boiling Water Reactor Environment on Stress Corrosion Crack Initiation and Growth in Type 304 Stainless Steel

1986 ◽  
Vol 108 (1) ◽  
pp. 10-19 ◽  
Author(s):  
C. W. Jewett ◽  
A. E. Pickett
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Fracture Mechanics ◽  
Crack Initiation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
304 Stainless Steel ◽  
Full Size ◽  
Type 304 ◽  
Type 304 Stainless Steel

Intergranular Stress Corrosion Cracking (IGSCC) in Type 304 stainless steel in high temperature high purity water requires the simultaneous presence of sensitized material, high tensile stress and oxygen. Laboratory and in-reactor stress corrosion tests have shown the benefits of adding hydrogen to the boiling water reactor feed-water to reduce the dissolved oxygen concentration and thereby reduce the chemical driving force for IGSCC. The purpose of this program was to verify the benefit of hydrogen additions on the stress corrosion crack behavior. The program investigated the fatigue and constant load crack growth behavior using fracture mechanics specimens in hydrogen water chemistry (HWC). Isothermal heat treatments were used to sensitize Type 304 stainless steel. Additionally, full size pipe tests containing actual welds were used to evaluate crack initiation, as well as propagation of cracks, to verify the results of the fracture mechanics tests. These pipe tests were performed under a trapezoidal loading cycle. The results of the small specimen tests show that HWC inhibits IGSCC in Type 304 stainless steel. The effects of cyclic loading at slow frequencies which promote IGSCC were also evaluated. Computer aided methods were used in the collection and interpretation of the high temperature crack growth data. The full-size component tests substantiated the benefit of HWC in both crack initiation and growth. All results presented were compared to baseline test data to put the results into perspective.

STRESS CORROSION CRACK INITIATION BEHAVIOR FOR THE X70 PIPELINE STEEL BENEATH A DISBONDED COATING

2012 ◽  
Vol 48 (10) ◽  
pp. 1267 ◽  
Author(s):  
Zhiying WANG ◽  
Jianqiu WANG ◽  
En-hou HAN ◽  
Wei KE ◽  
Maocheng YAN ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Disbonded Coating

Modeling the Interactions of Hydrogen, Stress and Dissolution in Near-Neutral pH Stress Corrosion Cracking of Pipelines

2006 ◽  
Author(s):  
Frank Y. Cheng
Keyword(s):  
Stress Corrosion ◽  
Dissolution Rate ◽  
Crack Growth ◽  
Anodic Dissolution ◽  
Hydrogen Concentration ◽  
Stress Corrosion Cracking ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Neutral Ph ◽  
Ph Stress

A thermodynamic model was developed to determine the interactions of hydrogen, stress and anodic dissolution at the crack-tip during near-neutral pH stress corrosion cracking in pipelines. By analyzing the free-energy of the steel in the presence and absence of hydrogen and stress, it is demonstrated that a synergism of hydrogen and stress promotes the cracking of the steel. The enhanced hydrogen concentration in the stressed steel significantly accelerates the crack growth. The quantitative prediction of the crack growth rate in near-neutral pH environment is based on the determination of the effect of hydrogen on the anodic dissolution rate in the absence of stress, the effect of stress on the anodic dissolution rate in the absence of hydrogen, the synergistic effect of hydrogen and stress on the anodic dissolution rate at the crack-tip and the effect of the variation of hydrogen concentration on the anodic dissolution rate.

Modeling of Fatigue Crack Propagation

2004 ◽  
Vol 126 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Yanyao Jiang ◽  
Miaolin Feng
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Fatigue Crack Propagation ◽  
Fatigue Crack Initiation ◽  
Cyclic Plasticity ◽  
R Ratio

Fatigue crack propagation was modeled by using the cyclic plasticity material properties and fatigue constants for crack initiation. The cyclic elastic-plastic stress-strain field near the crack tip was analyzed using the finite element method with the implementation of a robust cyclic plasticity theory. An incremental multiaxial fatigue criterion was employed to determine the fatigue damage. A straightforward method was developed to determine the fatigue crack growth rate. Crack propagation behavior of a material was obtained without any additional assumptions or fitting. Benchmark Mode I fatigue crack growth experiments were conducted using 1070 steel at room temperature. The approach developed was able to quantitatively capture all the important fatigue crack propagation behaviors including the overload and the R-ratio effects on crack propagation and threshold. The models provide a new perspective for the R-ratio effects. The results support the notion that the fatigue crack initiation and propagation behaviors are governed by the same fatigue damage mechanisms. Crack growth can be treated as a process of continuous crack nucleation.

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