Study on Effects of Non-Isothermal Condition and Strain Holding on Environmentally Assisted Fatigue in PWR Primary Water Environment (Step III)

2019 ◽  
Author(s):  
Daiki Takagoshi ◽  
Seiji Asada ◽  
Yuichirou Nomura ◽  
Gary Stevens ◽  
Kawaljit Ahluwalia
Keyword(s):  
Water Environment ◽  
Isothermal Condition ◽  
Austenitic Stainless Steels ◽  
Fatigue Tests ◽  
Small Scale ◽  
Pressurized Water ◽  
Transient Conditions ◽  
Isothermal Conditions ◽  
Primary Water ◽  
Isothermal Test

Abstract To further understand the environmentally assisted fatigue (EAF) behavior of Type 316 austenitic stainless steels (SS) in a pressurized water reactor (PWR) primary water environment, the influence of non-isothermal transient conditions was investigated using hollow, small-scale fatigue specimens. In our previous study (Step I: PVP2016-63798), isothermal and non-isothermal EAF tests were performed. The non-isothermal transient conditions for the fatigue tests investigated transients that consisted of both in-phase and out-of-phase temperature and strain variations. The result of this test series showed longer fatigue lives than those predicted using the modified rate approach and the EAF multiplier (Fen) presented in the draft of NUREG/CR-6909, Revision 1. In our follow-on study (Step II: PVP2017-66233), one extra non-isothermal test was performed and application of the Weighted Stress Intensity Factor (K) Rate (WKR) method was discussed. In the latest Step III testing, an extra non-isothermal test with periodic beachmarking has been performed. This paper discusses, based on the completion of all EAF tests performed in Steps I – III of this project, the effects of non-isothermal conditions and recommendations which are made for treatment of non-isothermal conditions in EAF assessments.

Study on Effects of Non-Isothermal Condition and Strain Holding on Environmentally Assisted Fatigue in PWR Primary Water Environment

2016 ◽  
Author(s):  
Seiji Asada ◽  
Yuichi Fukuta ◽  
Kawaljit Ahluwalia ◽  
David Steininger
Keyword(s):  
Fatigue Behavior ◽  
Hold Time ◽  
Water Environment ◽  
Isothermal Condition ◽  
Austenitic Stainless Steels ◽  
Strain Range ◽  
Fatigue Tests ◽  
Test Material ◽  
Strain Rate Change ◽  
Primary Water

To understand the fatigue behavior of austenitic stainless steels in a simulated PWR primary water environment, the patterns were studied. Austenitic stainless steel Type 316 plate was used as the test material. Regarding non-isothermal testing: isothermal and non-isothermal fatigue tests were carried out for several patterns of temperature change and strain rate change. Typically, fatigue lives for non-isothermal tests with an out-of-phase strain change pattern were longer than those for isothermal tests. Regarding strain holding testing: multiple groups of strain range cycles were separated by a long hold time and several test cases were carried out. Testing shows there is little difference in fatigue life for strain holding tests with high strain amplitude.

Effects of Primary Water Environment on the Thermal Aged Cast Austenitic Stainless Steels

2015 ◽  
Author(s):  
Yuichi Fukuta ◽  
Hiroshi Kanasaki ◽  
Takahisa Yamane
Keyword(s):  
Fracture Toughness ◽  
Stainless Steels ◽  
Water Environment ◽  
Prediction Method ◽  
Austenitic Stainless Steels ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Ferrite Content ◽  
Pressurized Water ◽  
Primary Water

This report summarizes the results of a scoping fracture toughness tests at high and low temperature for thermally aged cast austenitic stainless steels (CASSs) in a pressurized water reactor (PWR) environment. CF8M (ferrite content = 10.1%, 18.9%) and CF8 (ferrite content = 10.5%) were thermally aged up to 5,000 hours at 465°C. Tensile tests, Charpy impact tests and fracture toughness tests were conducted in air at 325°C and 50°C. Fracture toughness tests were also performed in simulated PWR primary water. Although the effect of 325°C and 50°C in simulated PWR primary water and dissolved hydrogen on the fracture toughness (JIc and J-Δa relationship) were slightly observed, fracture toughness was greater than that predicted by the thermally aged fracture toughness prediction method (Hyperbolic-Time-Temperature-Toughness (H3T) model).

Study on Effects of Non-Isothermal Condition and Strain Holding on Environmentally Assisted Fatigue in PWR Primary Water Environment: Step II

2017 ◽  
Author(s):  
Seiji Asada ◽  
Daiki Takagoshi ◽  
Yuichi Fukuta ◽  
Kazuya Tsutsumi ◽  
Kawaljit Ahluwalia ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Fatigue Behavior ◽  
Compressive Strain ◽  
Water Environment ◽  
Isothermal Condition ◽  
Fatigue Tests ◽  
Transient Condition ◽  
Isothermal Fatigue ◽  
Primary Water

In order to understand the fatigue behavior in PWR primary water environment, the influence of non-isothermal transient condition was investigated for austenitic stainless steel 316SS. In our previous study (PVP2016-63798), isothermal and non-isothermal environmentally assisted fatigue tests were performed. The fatigue life of the non-isothermal fatigue test consisted of a high temperature and tensile strain rate transient, a portion of which occurred in the compressive strain region of the strain cycle. The result of this test showed longer life than the predicted fatigue life estimated by the modified rate approach and Fen factor as presented in NUREG/CR-6909 Rev.1. In this paper, the reason why the fatigue test showed longer fatigue life is studied. Crack growth analysis was performed to understand the effect of the environment on fatigue life. Additionally, application of the Weighted K Rate (WKR) method described in reference (PVP2016-63497) was applied to a series of tests. This approach showed good agreement on fatigue life for a number of different waveforms for isothermal tests. The methodology was applied to some of this investigation’s non-isothermal fatigue tests and shown to be an improvement that justifies further investigation.

scholarly journals Fatigue Damage Management According to Performance Based Maintenance (PBM) Concept

2021 ◽  
Author(s):  
Masayuki Kamaya
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Thermal Loading ◽  
Water Environment ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Term Operation ◽  
Primary Water ◽  
Crack Growth Curve

Abstract A maintenance concept of performance based maintenance (PBM) has been proposed by the current author. According to the PBM concept, inspection results are considered in determining the next inspection schedule. In this study, this concept was applied to fatigue degradation for stainless steel components in the pressurized water reactor (PWR) primary water environment. It is possible to estimate the fatigue life for the PWR water environment from that obtained in an air environment and the parameter Fen, which represents the ratio of the fatigue life in the air and PWR water environments. It was shown that the fatigue life prediction using Fen can be replaced by the crack growth analysis using the growth rate for the PWR water environment. Then, the crack growth was predicted for a thermal loading assuming the growth occurred in the PWR water environment. It was shown that the duration until the next inspection could be optimized based on the inspection results together with the crack growth curve. A long term operation before the inspection resulted in a longer duration until the next inspection.

Effects of cold deformation on electrochemical corrosion behaviors of 304 stainless steel

2017 ◽  
Vol 64 (2) ◽  
pp. 252-262 ◽  
Author(s):  
Jiamei Wang ◽  
Le Fu Zhang
Keyword(s):  
Stainless Steel ◽  
Nuclear Power ◽  
Cold Deformation ◽  
Water Environment ◽  
Electrochemical Corrosion ◽  
Pressurized Water ◽  
Content Type ◽  
304 Austenitic Stainless Steel ◽  
Primary Water ◽  
Corrosion Behaviors

Purpose The purpose of this study was to investigate the effects of deformation-induced martensite on electrochemical corrosion behaviors of 304 austenitic stainless steel in a simulated primary water environment of a pressurized water reactor nuclear power plant with boric acid and lithium hydroxide contaminated with chloride by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Mott–Schotty curves and X-ray photoelectron spectroscopy (XPS). Design/methodology/approach The effects of deformation-induced martensite transformation on electrochemical corrosion behaviors of 304 austenitic stainless steel was investigated in a simulated primary water environment of a pressurized water reactor nuclear power plant with boric acid and lithium hydroxide contaminated with 0.1 M Cl− by potentiodynamic polarization, EIS, Mott–Schotty curves and XPS in this paper. Findings The results revealed that the martensitic phase contents increased with the level of cold deformation. The general corrosion current density and the corrosion potential increased and decreased, respectively, with the increase of cold deformation degree. However, the pitting potential decreased as the cold deformation increased up to 20 per cent, then a slight increase was observed at 35 per cent cold working. It was found from Mott–Schottky curves and XPS analysis that as the cold deformation degree increased from 0 to 35 per cent, the doping concentrations of the oxide films increased; however, the film thickness decreased, which indicates that both density and integrity of the films are degraded significantly as the deformation degree increases, and this ultimately contributes to the significant increment of the general corrosion rate and reduction of the pitting corrosion resistance. Originality/value The effects of deformation-induced martensite transformation on electrochemical corrosion behaviors of 304 austenitic stainless steel was investigated in a simulated primary water environment of a pressurized water reactor nuclear power plant with boric acid and lithium hydroxide contaminated with 0.1 M Cl− by potentiodynamic polarization, EIS, Mott–Schotty curves and XPS in this paper.

Study on electrochemical behavior of 690 alloy with corrosion products in simulated PWR primary water environment

2018 ◽  
Vol 65 (6) ◽  
pp. 616-625
Author(s):  
Xuequn Cheng ◽  
Xiao Mei Zuo
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Electrochemical Behavior ◽  
Water Environment ◽  
Corrosion Products ◽  
Inhibition Mechanism ◽  
Pressurized Water ◽  
Content Type ◽  
Primary Water ◽  
Immersion Testing

Purpose The purpose of this paper is to study the electrochemical behavior of 690 alloy with corrosion products in simulated pressurized water reactor (PWR) primary water environment. Design/methodology/approach This paper opted for a laboratory study using simulation of high temperature and high pressure environment immersion testing. The electrochemical behavior was studied by potentiodynamic polarization, electrochemical impedance spectroscopy, scanning Kelvin probe microscopy (SKP). Moreover, the corrosion products were analyzed by X-ray photoelectron spectroscopy. Findings The results demonstrated that the particle majority in the 690 alloy corrosion products subsequent to high temperature and high pressure immersion testing were mainly oxides of Fe and Ni, which protected the matrix. As the immersion testing duration increased, the corrosion potential of the 690 alloy apparently increased, and the corrosion current density de'creased, while the corrosion resistance Rf increased gradually along with the density. The SKP demonstrated that the EKP increased by nearly 400 mV from −0.42 to −0.03 V following the immersion testing, indicating that the corrosion product film played an apparent protective role on the substrate. Originality/value This paper provides a theoretical basis for the corrosion behavior and inhibition mechanism of 690 alloy in PWR primary water environment.

Method for Estimation of Pressure Vessel Internals Lifetime on IASCC Criterion

2013 ◽  
Author(s):  
Valentina Fedorova ◽  
Boris Margolin
Keyword(s):  
Grain Boundary ◽  
Water Environment ◽  
Austenitic Stainless Steels ◽  
Grain Boundary Sliding ◽  
Pressure Vessels ◽  
Neutron Dose ◽  
Austenitic Steels ◽  
Pressurized Water ◽  
Boundary Sliding ◽  
Water Reactors

Austenitic stainless steels are used extensively as structural materials in the internal components of reactor pressure vessels. However, high neutron doses lead to a significant reduction in the fracture resistance of these steels in water environment. Irradiation assisted stress corrosion cracking (IASCC) of internals has been observed in pressurized water reactors (PWRs). In the present work the IASCC model of the irradiated austenitic steels in PWR water has been developed. On the basis of analysis of available experimental data IASCC mechanism is proposed. Based on this mechanism, the dependence of fracture stress under IASCC on neutron dose is derived. For its construction the following assumptions were made. 1. Creep rate due to grain boundary sliding does not depend on neutron dose. 2. Fracture strain due to grain boundary sliding decreases when neutron dose increases. 3. There is an apparent stress threshold below which IASCC initiation does not occur in PWR environment. Life prediction analysis for IASCC is performed on the basis of linear rule of damage accumulation.

Mean Stress Effect on Fatigue Properties of Type 316 Stainless Steel in Pressurized Water Reactors Primary Water Environment

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Masayuki Kamaya
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Water Environment ◽  
Stress Effect ◽  
Mean Stress ◽  
Pressurized Water ◽  
316 Stainless Steel ◽  
Mean Stress Effect ◽  
Primary Water ◽  
The Mean

The mean stress effect on the fatigue life of type 316 stainless steel was investigated in simulated pressurized water reactor (PWR) primary water and air at 325 °C. The tests in air environment have revealed that the fatigue life was increased with application of the positive mean stress for the same stress amplitude because the strain range was decreased by hardening of material caused by increased maximum peak stress. On the other hand, it has been shown that the fatigue life obtained in simulated PWR primary water was decreased compared with that obtained in air environment even without the mean stress. In this study, type 316 stainless steel specimens were subjected to the fatigue test with and without application of the positive mean stress in high-temperature air and PWR water environments. First, the mean stress effect was discussed for high-temperature air environment. Then, the change in fatigue life in the PWR water environment was evaluated. It was revealed that the change in the fatigue life due to application of the mean stress in the PWR water environment could be explained in the same way as for the air environment. No additional factor was induced by applying the mean stress in the PWR water environment.

scholarly journals PWR effect on crack initiation under equi-biaxial loading development of the experiment

2019 ◽  
Vol 20 (6) ◽  
pp. 619
Author(s):  
Cédric Gourdin ◽  
Gregory Perez ◽  
Hager Dhahri ◽  
Stéphan Courtin ◽  
Jean Christophe Le Roux ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Biaxial Loading ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Structural Effect ◽  
Fatigue Tests ◽  
Pressurized Water ◽  
Term Operation ◽  
New Device ◽  
Penalty Factor

The lifetime extension of the nuclear power stations is considered as an energy challenge worldwide. That is why, the risk analysis and the study of various effects of different factors that could potentially represent a hazard to a safe long term operation are necessary. The methodology for fatigue dimensions of the Pressurized Water Reactor components (PWR) is based on the use of design curves established from test carried out in air at 20 °C on smooth specimens by integrating safety coefficient that covers the dispersion of tests associated with the effects of structures. To formally integrate these effects, some international codes have already proposed and suggested a modification of the austenitic stainless steels fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which has to be multiplied by the usual fatigue usage factor. The aim of this paper is to present a new device “FABIME2E” developed in the CEA-LISN in collaboration with EDF and AREVA. These new tests allow quantifying accurately the effect of PWR environment on semi-structure specimen. This new device combines the structural effect like equi-biaxiality and mean strain and the environmental penalty effect with the use of PWR environment during the fatigue tests.

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