Research on the Application of FEN for EAF Evaluation of the Austenitic SS Pipe Under Combined Transient Loads

2017 ◽  
Author(s):  
Bingbing Liang ◽  
Xu Zhang ◽  
Haifeng Yin ◽  
Yang Dai
Keyword(s):  
Research Work ◽  
Water Environment ◽  
Combined Loading ◽  
Light Water Reactor ◽  
Light Water ◽  
Thermal Transient ◽  
Materials Used ◽  
Conservative Result ◽  
Fatigue Life Reduction ◽  
Temperature Strain

Accumulative test data indicates that the effects of the light water reactor (LWR) environment could cause the fatigue resistance of materials used in the reactor coolant pressure boundary components to significantly reduce. EAF is used as the abbreviation of the environmentally assisted fatigue in the nuclear field. In 2007, NRC issued RG. 1.207. It was updated in 2014. And it requires that the effects of the light-water environment on the fatigue life reduction of metal components should be considered for new plants. And it suggests to use environmental correction factor (Fen) to account for EAF. Fen = Nair/Nwater (N is occurrences). NUREG/CR-6909 [1] presents the detail Fen calculation formula which includes the complicated influence of combined multi-parameters. Fen is a function of temperature, strain amplitude & rate, dissolved oxygen level in water, and sulfur content of the steel. Accordingly, Fen calculation will present a comparatively conservative result. Depends on the experience of the primary pressure boundary piping transient operation, Fen vary during each transient. More uncertainty and confusion are raised during the application of the Fen method. In the research work involved in this article, first, the typical character of piping thermal transient is derived based on the existing experience. Second, small specimen EAF tests are conducted depend on the above derived combined loading characters. Then effort is taken to improve the application of the Fen method for the combined multi-transient loading conditions. And the result is compared with that of the lowest instantaneous Fen method and equalization of the weighted Fen method. Finally, a designed test matrix is needed to prove its practicability furthermore.

Research on the Application of Fen for Environmentally Assisted Fatigue Evaluation of the Austenitic SS Pipe Under Combined Transient Loads

2018 ◽  
Vol 4 (4) ◽  
Author(s):  
Bingbing Liang ◽  
Xu Zhang ◽  
Haifeng Yin ◽  
Yang Dai
Keyword(s):  
Fatigue Life ◽  
Research Work ◽  
Nuclear Regulatory Commission ◽  
Combined Loading ◽  
Reactor Materials ◽  
Fatigue Evaluation ◽  
Regulatory Commission ◽  
Conservative Result ◽  
Fatigue Life Reduction ◽  
Temperature Strain

Accumulative test data indicate that the effects of the light water reactor (LWR) environment could cause the fatigue resistance of primary pressure boundary components materials to be significantly reduced. Environmentally assisted fatigue (EAF) is the abbreviation of the environmentally assisted fatigue. In 2007, Nuclear Regulatory Commission (NRC) issued RG. 1.207. It was updated in 2014. And, it requires that the effects of LWR environment on the fatigue life reduction of metal components should be considered for new design plants. And it suggests to use environmental correction factor, Fen, to account for EAF. NRC regulation (NUREG), NUREG/CR-6909 (NRC, 2013, “Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials,” U.S. Nuclear Regulatory Commission, Argonne, IL, Standard no. NUREG/CR-6909), presents the detail Fen calculation formula. Fen is a function of temperature, strain rate, dissolved oxygen level in water, and sulfur content of the steel. Accordingly, Fen calculation will present a comparatively conservative result. Depending on the experience of the primary pressure boundary piping transient operation, Fen varies during each transient. More uncertainty and confusion are raised during the application of the Fen method. The research work in this paper includes: first, the typical character of piping thermal transient is derived based on the existing experience. Second, small specimen EAF tests are conducted depending on the above derived combined loading characters. Then effort is taken to improve the application of the Fen method for the combined multitransient loading conditions. And the results are compared with those of the lowest instantaneous Fen method and equalization of the weighted Fen method. Finally, a designed test plan 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.

Revised Proposal of Fatigue Life Correction Factor Fen for Carbon and Low Alloy Steels in LWR Water Environments

2004 ◽  
Vol 126 (4) ◽  
pp. 438-444 ◽  
Author(s):  
Makoto Higuchi
Keyword(s):  
Fatigue Life ◽  
Correction Factor ◽  
Light Water Reactor ◽  
Low Alloy Steels ◽  
Light Water ◽  
High Temperature Water ◽  
Fatigue Data ◽  
Alloy Steels ◽  
Fatigue Life Reduction ◽  
Temperature Water

The fatigue life of carbon and low alloy steels decreases with reduction in strain rate in high temperature water such as in the case of a light water reactor coolant. The fatigue life reduction also depends on temperature and dissolved oxygen. The fatigue life correction factor Fen has been proposed as a method to assess the fatigue life reduction in such environments. Three different models for calculating Fen for carbon and low alloy steels have been proposed by Higuchi et al., Chopra et al., and Mehta. These models were compared using considerable environmental fatigue data that were tested and published in Japan and USA and piled up in the database “JNUFAD” by the author. These models give somewhat different results in the specific conditions and a revised model for calculating Fen is thus proposed by remedying the particular drawbacks of each. In this model, the same formula is used for carbon and low alloy steels and S*,T*,O*, and ε˙* are adopted in the formula after reevaluating every parameter. The revised proposal shows better correlation with the test data than the previous models.

Results of reliability test program on light water reactor piping

1994 ◽  
Vol 153 (1) ◽  
pp. 71-86 ◽  
Author(s):  
K. Shibata ◽  
T. Isozaki ◽  
S. Ueda ◽  
R. Kurihara ◽  
K. Onizawa ◽  
...  
Keyword(s):  
Light Water Reactor ◽  
Reliability Test ◽  
Test Program ◽  
Light Water ◽  
Water Reactor

Parametric Study of External Pressure on Steam Generator Tube Bends

2012 ◽  
Author(s):  
Mitch Hokazono ◽  
Clayton T. Smith
Keyword(s):  
Steam Generator ◽  
Parametric Study ◽  
External Pressure ◽  
Light Water Reactor ◽  
Material Strength ◽  
Steam Generators ◽  
Elliptical Cross ◽  
Light Water ◽  
Water Reactor ◽  
Steam Generator Tubes

Integral light-water reactor designs propose the use of steam generators located within the reactor vessel. Steam generator tubes in these designs must withstand external pressure loadings to prevent buckling, which is affected by material strength, fabrication techniques, chemical environment and tube geometry. Experience with fired tube boilers has shown that buckling in boiler tubes is greatly alleviated by controlling ovality in bends when the tubes are fabricated. Light water reactor steam generator pressures will not cause a buckling problem in steam generators with reasonable fabrication limits on tube ovality and wall thinning. Utilizing existing Code rules, there is a significant design margin, even for the maximum differential pressure case. With reasonable bend design and fabrication limits the helical steam generator thermodynamic advantages can be realized without a buckling concern. This paper describes a theoretical methodology for determining allowable external pressure for steam generator tubes subject to tube ovality based on ASME Section III Code Case N-759-2 rules. A parametric study of the results of this methodology applied to an elliptical cross section with varying wall thicknesses, tube diameters, and ovality values is also presented.

Conservative Width of High-Burnup Structure in Light Water Reactor UO2Fuel as a Function of Pellet Average Burnup

2008 ◽  
Vol 164 (3) ◽  
pp. 337-347 ◽  
Author(s):  
Yang-Hyun Koo ◽  
Byung-Ho Lee ◽  
Jae-Yong Oh ◽  
Kun-Woo Song
Keyword(s):  
Light Water Reactor ◽  
Light Water ◽  
Water Reactor ◽  
High Burnup
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