Fatigue Crack Growth Rate of Medium and Low Sulfur Ferritic Steels in Pressurized Water Reactor Primary Water Environments

2003 ◽  
Vol 125 (4) ◽  
pp. 385-392
Author(s):  
Ernest D. Eason ◽  
Edward E. Nelson ◽  
Graham B. Heys
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Primary Water ◽  
Low Sulfur

Models of fatigue crack growth rates for medium and low sulfur ferritic pressure vessel steels in pressurized water reactor (PWR) primary environments are developed based on a recent collection of UK data and the EPRI Database for Environmentally Assisted Cracking (EDEAC). The combined UK and EDEAC database contains a broader range of experimental conditions specific to PWRs than either database by itself. Both probabilistic and conventional crack growth rate models are developed that reduce unnecessary conservatism for medium and low sulfur PWR primary water applications and eliminate the explicit dependence on rise time that caused difficulties applying prior models.

Fatigue Crack Growth Rate of Medium and Low Sulfur Ferritic Steels in Pressurized Water Reactor Primary Water Environments

2003 ◽  
Author(s):  
Ernest D. Eason ◽  
Edward E. Nelson ◽  
Graham B. Heys
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Primary Water ◽  
Low Sulfur

Models of fatigue crack growth rates for medium and low sulfur ferritic pressure vessel steels in pressurized water reactor (PWR) primary environments are developed based on a recent collection of UK data and the EPRI Database for Environmentally Assisted Cracking (EDEAC). The combined UK and EDEAC database contains a broader range of experimental conditions specific to PWRs than either database by itself. Both probabilistic and conventional crack growth rate models are developed that reduce unnecessary conservatism for medium and low sulfur PWR primary water applications and eliminate the explicit dependence on rise time that caused difficulties applying prior models.

Effect of Loading Waveform and Spectrum Loading on the Fatigue Crack Growth Rate in Simulated Light Water Reactor Environments

2016 ◽  
Author(s):  
Norman Platts ◽  
Keith Rigby ◽  
David R. Tice ◽  
David I. Swan
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Rise Time ◽  
Light Water Reactor ◽  
Light Water ◽  
Water Reactor ◽  
Rate Retardation

High temperature water environments, typical of light water reactor primary coolant, are known to lead to significant environmental enhancement of fatigue crack growth of austenitic stainless steels. For PWR environments. these effects have recently been codified in ASME Code Case N-809. However, just as for the detrimental effect of these environments on fatigue endurance, plant experience indicates that crack growth rates must be significantly lower than predictions based on laboratory data using simple sawtooth waveforms. In order to explain this discrepancy, a significant amount of research has been conducted to quantify factors leading to crack growth rate retardation with sulfur content having been identified as significant in promoting crack growth rate retardation. However, the inherent conservatisms in current analysis techniques may be just as significant in generating the perceived over-conservatism of environmental fatigue crack growth laws such as Code Case N-809. The current work looks at the impact of waveform shape and spectrum loading on the level of environmental enhancement for a given stress intensity factor range and total rise time by considering simplified transients and loading spectra. The observations suggest that simplified definitions of total rise time used in fatigue assessments can lead to large over-estimation of actual fatigue damage. These data form the basis of an analytical methodology being developed by RollsRoyce (presented in a separate paper at this conference) aimed at partitioning damage across the loading cycle in order to remove over-conservatisms in current analytical methodologies.

Effect of Uneven Crack Front on Crack Tip Mechanics and the Implication to Stress Corrosion Crack Growth

2009 ◽  
Author(s):  
He Xue ◽  
Zhanpeng Lu ◽  
Hiroyoshi Murakami ◽  
Tetsuo Shoji
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Crack Front ◽  
Pressurized Water Reactor ◽  
Element Analysis ◽  
Pressurized Water ◽  
Water Reactor ◽  
Nickel Base

Uneven crack fronts have been observed in laboratory stress corrosion cracking tests. For example, cracking fronts of nickel-base alloys tested in simulated boiling water reactor (BWR) and pressurized water reactor (PWR) environments could exhibit uneven crack front. Analyzing the effect of an uneven crack front on further crack growth is important for quantification of crack growth. Finite-Element analysis shows that the local KI distribution can be significantly affected by the shape and size of the uneven crack front. Stress intensity factor at the locally extended crack front can be significantly reduced. Since generally there is a nonlinear CGR versus KI relationship, it is expected that crack growth rate at the locally extended crack front can be significantly different from those in the neighboring areas. There could be several patterns for the growth of an uneven crack front. For example, once initiated, the crack growth rate in areas other than the locally protruded front would become higher and then the whole crack front would tend to become uniform. On the other hand, if the crack growth in other areas is still low, there is a possibility that the crack growth rate at the front tip would slow down.

Effects of Dissolved Hydrogen on Crack Growth Rate of Warm-Rolled 316L Austenitic Stainless Steel in Primary Water Condition

2015 ◽  
Author(s):  
Kyoung Joon Choi ◽  
Seung Chang Yoo ◽  
Taeho Kim ◽  
Seong Sik Hwang ◽  
Min Jae Choi ◽  
...  
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Hydrogen Concentration ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Condition ◽  
Primary Water ◽  
Dissolved Hydrogen

With the extension of pressurized water reactor’s design life or continued operation, more careful study on the integrity of the internal structures needs to be pursued. In this study, warm-rolling and heat-treatment were applied to 316L stainless steel, in order to simulate the effect of radiation damage such as hardening and radiation-induced grain boundary segregation. And, the crack growth rate testing under constant load condition was performed in the primary water conditions of a pressurized water reactor. Also, in order to investigate the effect of dissolved hydrogen on the crack growth, the dissolved hydrogen concentration was varied between 30 to 50 cc/kg in simulated primary water condition of a pressurized water reactor. The warm-rolled specimens showed the higher crack growth rate than as-received one. Also, the crack growth rate increased as the dissolved hydrogen concentration increases.

Negative Load Ratio Fatigue Crack Growth Rate Testing on Austenitic Stainless Steel in a Simulated Primary Water Environment

2015 ◽  
Author(s):  
Norman Platts ◽  
David R. Tice ◽  
Wenzhong Zhang
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Loading Test ◽  
Element Analysis ◽  
Pressurized Water ◽  
Test Methodology

Light water reactor coolant environments are known to significantly enhance the fatigue crack growth rate of austenitic stainless steels. However, most available data in these high temperature pressurized water environments have been derived using specimens tested at positive load ratios, whilst many plant transients involve significant compressive as well as tensile stresses. The extent to which the compressive loading impacts on the environmental enhancement of fatigue crack growth and more importantly on the processes leading to retardation of those enhanced rates is therefore unclear, potentially leading to excessive conservatism in current assessment methodologies. A test methodology using corner cracked tensile specimens has been developed which provides significant advantages over more conventional specimen geometries in terms of autoclave testing at negative load ratios. Finite element analysis of the specimen geometry has been performed to generate effective stress intensity factors, Keff, for specimens loaded in fully reverse loading. Test data generated in both air and water are compared to conventional compact tension specimen data to validate the test methodology.

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