Deterministic Prediction of Stress Corrosion Crack Growth Rates in High Temperature Water by Combination of Interface Oxidation Kinetics and Crack Tip Asymptotic Field

Author(s):  
Tetsuo Shoji ◽  
Zhanpeng Lu ◽  
Yoichi Takeda ◽  
Hiroyoshi Murakami ◽  
Chaoyang Fu

Proper disposition of the environmentally assisted crack growth rate in terms of key engineering parameters is crucial for safe and economic long term operation of light water reactors. Accurately predicting stress corrosion crack growth rate requires the quantification of crack tip mechanics, crack tip oxidation kinetics and their interactions. Crack tip strain rate has been categorized as a fundamental parameter for stress corrosion cracking of austenitic alloys in light water reactor environments. Continuum mechanics is applied to quantify crack tip strain rate based on the crack tip asymptotic field. A general oxidation kinetics formulation is proposed based on solid state mass transport theory. Stress corrosion crack growth rates of austenitic alloys in high temperature water environments are formulated as a function of various engineering parameters by combination of interface oxidation kinetics and the crack tip asymptotic field. Recent experimental results of stress corrosion crack growth rates in simulated boiling water reactor and pressurized water reactor environments are analyzed and reflected in the model development and application. The importance of surface integrity on plant safety is emphasized. The plant material aging management methodology is applied to the recent cracking issues in light water reactors.

Author(s):  
M. R. Fourozan ◽  
M. Olfatnia ◽  
S. J. Golestaneh

In this paper, a quantitative study on stress corrosion crack growth in large diameter gas pipelines is presented. Finite element method is applied for determining stress intensity factor at the crack tip. First a small semi-elliptical axial surface crack is assumed. Then internal gas pressure and residual stress, induced from welding process, are considered. Applied forces and crack growth rate are calculated as a function of stress intensity factor based on an empirical equation. Crack front shape is determined by calculating stress intensity factor distributions along the crack tip. As a result, the effect of residual stress on stress intensity factor and therefore crack growth is determined. In addition, minimum crack size that activates the stress corrosion cracking mechanism is determined. It is shown that the applied method could be used to estimate the reliable life of pipeline and the suitable time for inspection of the pipeline’s surface.


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