A Consideration of Margin on Fatigue Design Curves for Carbon and Low-Alloy Steels

2011 ◽  
Author(s):  
Makoto Higuchi ◽  
Masahiro Takanashi ◽  
Ichiro Tamura ◽  
Toshiaki Takada
Keyword(s):  
Stainless Steels ◽  
Fatigue Curve ◽  
Light Water Reactor ◽  
Ferritic Steels ◽  
Low Alloy Steels ◽  
Light Water ◽  
Fatigue Design ◽  
The Us ◽  
Asme Code ◽  
Alloy Steels

In 2007, the US NRC issued Regulatory Guide 1.207[1] and NUREG/CR-6909[2] for evaluating fatigue incorporating the life reduction due to the effects of light-water reactor environment for new reactors. NUREG/CR-6909 provides new design fatigue curves (DFC) for carbon, low-alloy and stainless steels which are different from those in the ASME Boiler and Pressure Vessel Code Section III[3] (2007 Edition). The design fatigue curves for carbon and low-alloy steels in NUREG/CR-6909 are higher than that for ferritic steels of which specified minimum tensile strength is 552 MPa (80 ksi) or less in the ASME Code Section III. The design fatigue curve for stainless steel in the ASME Code Section III was changed to the same curve as NUREG/CR-6909 in the 2009 Addenda. However, those for carbon and low-alloy steels are still different from the NUREG curves.

Sample Environmental Fatigue Calculations Associated With the Review of Draft Regulatory Guide DG-1144

2007 ◽  
Author(s):  
Gary L. Stevens ◽  
J. Michael Davis ◽  
Les Spain
Keyword(s):  
Stainless Steel ◽  
Lessons Learned ◽  
Light Water Reactor ◽  
Low Alloy Steels ◽  
Light Water ◽  
New Model ◽  
Asme Code ◽  
Alloy Steels ◽  
Reactor Materials ◽  
License Renewal

Draft Regulatory Guide DG-1144 “Guidelines for Evaluating Fatigue Analyses Incorporating the Life Reduction of Metal Components Due to the Effects of the Light-Water Reactor Environment for New Reactors”, July 2006 [1], and Associated Basis Draft Document NUREG/CR-6909 (ANL-06/08), “Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials”, July 2006 [6] provided methods for addressing environmentally assisted fatigue (EAF) in all new nuclear plant designs. In these documents, a new model was proposed that more accurately accounts for actual plant conditions. The new model includes an EAF correction factor, Fen, which is different from Fen methods previously and currently being considered for adoption into the ASME Code. The Fen methods proposed in DG-1144 are also different than the Fen methods utilized by license renewal applicants, as required by the Generic Aging Lessons Learned (GALL) report [2], as documented in NUREG/CR-5704 [4] (for stainless steel) and NUREG/CR-6583 [3] (for carbon and low alloy steels).

Margins for ASME Code Fatigue Design Curve: Effects of Surface Finish and Material Variability

2003 ◽  
Author(s):  
O. K. Chopra ◽  
W. J. Shack
Keyword(s):  
Pressure Vessel ◽  
Nuclear Power ◽  
Environmental Parameters ◽  
Light Water Reactor ◽  
Code Design ◽  
Low Alloy Steels ◽  
Design Curve ◽  
Fatigue Design ◽  
Asme Code ◽  
Alloy Steels

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. This Code specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life (ε-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of the existing fatigue ε-N data for carbon and low-alloy steels and wrought and cast austenitic SSs to define the effects of key material, loading, and environmental parameters on the fatigue lives of the steels. Experimental data are presented on the effects of surface roughness on the fatigue life of these steels in air and LWR environments. Statistical models are presented for estimating the fatigue ε-N curves as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue evaluations. A critical review of the margins for the ASME Code fatigue design curve is presented.

Development of a Fatigue Design Curve for Austenitic Stainless Steels in LWR Environments: A Review

2002 ◽  
Author(s):  
Omesh K. Chopra
Keyword(s):  
Stainless Steels ◽  
Pressure Vessel ◽  
Type Strain ◽  
Nuclear Power ◽  
Austenitic Stainless Steels ◽  
Environmental Parameters ◽  
Light Water Reactor ◽  
Code Design ◽  
Fatigue Design ◽  
Asme Code

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components and specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain–vs.–life (ε–N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This paper reviews the existing fatigue ε–N data for austenitic stainless steels in LWR coolant environments. The effects of key material, loading, and environmental parameters, such as steel type, strain amplitude, strain rate, temperature, dissolved oxygen level in water, and flow rate, on the fatigue lives of these steels are summarized. Statistical models are presented for estimating the fatigue ε–N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue design curves.

scholarly journals Development of a Water Environment Fatigue Design Curve for Austenitic Stainless Steels

2003 ◽  
Author(s):  
Thomas R. Leax
Keyword(s):  
Stainless Steels ◽  
Fatigue Behavior ◽  
Water Environment ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Light Water Reactor ◽  
Design Curve ◽  
Fatigue Design ◽  
American Society ◽  
Design Factors

Technical support is provided for a fatigue curve that could potentially be incorporated into Section III of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code. This fatigue curve conservatively accounts for the effects of light water reactor environments on the fatigue behavior of austenitic stainless steels. This paper presents the data, statistical methods, and basis for the design factors appropriate for Code applications. A discussion of the assumptions and methods used in design curve development is presented.

Evaluation of Fatigue Damage in LWR Water With and Without Threshold and Moderation Factor

2003 ◽  
Author(s):  
Makoto Higuchi ◽  
Kazuya Tsutsumi ◽  
Katsumi Sakaguchi
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Power Plants ◽  
Light Water Reactor ◽  
Low Alloy Steels ◽  
Light Water ◽  
Water Reactor ◽  
Fatigue Data ◽  
Fatigue Life Reduction

During the past twenty years, the fatigue initiation life of LWR structural materials, carbon, low alloy and stainless steels has been shown to decrease remarkably in the simulated LWR (light water reactor) coolant environments. Several models for evaluating the effects of environment on fatigue life reduction have been developed based on published environmental fatigue data. Initially, based on Japanese fatigue data, Higuchi and Iida proposed a model for evaluating such effects quantitatively for carbon and low alloy steels in 1991. Thereafter, Chopra et al. proposed other models for carbon, low alloy and stainless steels by adding American fatigue data in 1993. Mehta developed a new model which features the threshold concept and moderation factor in Chopra’s model in 1995. All these models have undergone various revisions. In Japan, the MITI (Ministry of International Trade and Industry) guideline on environmental fatigue life reduction for carbon, low alloy and stainless steels was issued in September 2000, for evaluating of aged light water reactor power plants. The MITI guideline provide equations for calculations applicable only to stainless steel in PWR water and consequently Higuchi et al. proposed in 2002 a revised model for stainless steel which incorporates new equations for evaluation of environmental fatigue reduction in BWR water. The paper compares the latest versions of these models and discusses the conservativeness of the models by comparison of the models with available test data.

Overview of Fatigue Crack Initiation in Carbon and Low-Alloy Steels in Light Water Reactor Environments

1999 ◽  
Vol 121 (1) ◽  
pp. 49-60 ◽  
Author(s):  
O. K. Chopra ◽  
W. J. Shack
Keyword(s):  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Light Water Reactor ◽  
Code Design ◽  
Low Alloy Steels ◽  
Light Water ◽  
Water Reactor ◽  
Short Cracks ◽  
Alloy Steels ◽  
Current Code

Recent test data illustrate potentially significant effects of light water reactor (LWR) coolant environments on the fatigue resistance of carbon and low-alloy steels. The crack initiation and crack growth characteristics of carbon and low-alloy steels in LWR environments are presented. Decreases in fatigue lives of these steels in high-dissolved-oxygen water are caused primarily by the effect of environment on growth of short cracks <100 μm in depth. The material and loading parameters that influence fatigue life in LWR environments are defined. Statistical models have been developed to estimate the fatigue lives of these steels in LWR environments, and design fatigue curves have been developed for carbon and low-alloy steel components in LWR environments. The significance of environmental effect on the current Code design curve is evaluated.

Plan and Status of Development of Design Fatigue Curves: Phase 1

2013 ◽  
Author(s):  
Seiji Asada ◽  
Akihiko Hirano ◽  
Masao Itatani ◽  
Munehiro Yasuda ◽  
Takehiko Sera ◽  
...  
Keyword(s):  
Stainless Steels ◽  
Phase 1 ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Carbon Steels ◽  
Low Alloy Steels ◽  
Energy Research ◽  
Research Committee ◽  
Engineering Society ◽  
Alloy Steels

In order to develop and propose new design fatigue curves for austenitic stainless steels, carbon steels and low alloy steels that are rational and have clear design basis, Design Fatigue Curve (DFC) subcommittee has been established in the Atomic Energy Research Committee in the Japan Welding Engineering Society and the study on design fatigue curves are going on. This paper introduces the plan and status of the activities of the DFC subcommittee.

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