Residual stress by welding would be one of the most significant factors in evaluating failure probabilities of PLR piping since the SCC growth behavior is strongly affected by residual stress distribution. The residual stress distribution is well known to ch ange caused by varying of welding conditions such as groove shape, electrical voltage and current, inter-pass temperature, etc. Therefore, to evaluate the scatter of welding condition and their influence on residual stress is important to assess the st...
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Probabilistic Structural Integrity Assessment of Reactor Coolant Pressure Boundary Piping-1- The Scatter of Welding Conditions and Welding Residual Stress -

Stress corrosion cracking (SCC) in primary loop recirculation piping made of austenitic stainless steel has been observed near welding joints. The SCC grows near the welding zone mainly due to high tensile residual stress by welding as well as the other contributing f actors of material and environment. The residual stress analysis due to welding of austenitic stainless piping is important and has been already conducted by many researchers. In present work, the effect of scatters of welding conditions such...
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Probabilistic Structural Integrity Assessment of Reactor Coolant Pressure Boundary Piping-2- Residual Stress Analyses of the Effect of Scatter of Welding Conditions -

A probabilistic fracture mechanics (PFM) analysis code PASCAL-SP, which evaluates failure probabilities at welded joints in piping where being susceptible to stress corrosion cracking (SCC), h as been developed. This code is based on Monte Carlo simulation technique and Japanese code related to the SCC evaluation. Uncertainties and scatters of welding residual stress distribution we re modeled using database obtained from parametric FEM analyses. Sensitivity analyses concerning uncertainties and scatters o...
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Probabilistic Structural Integrity Assessment of Reactor Coolant Pressure Boundary Piping-3 - Probabilistic Fracture Mechanics Analyses Concerning Welding Residual Stress Distribution -

In nuclear power plants, stress corrosion cracking has been observed near the weld zone of the primary loop recirculation pipes made of low-carbon austenitic stainless steel Type 316L. Residual stress is important factor in the occurrence and propagation of SCC. The joining process of pipes usually includes surface machining and welding, and both processes induce residual stresses. In this study, FEM was used to estimate residual stress distributions generated by butt welding and surface machining. In addi...
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Evaluation of Residual Stress Distribution due to Welding and Surface Machining and Crack Growth Behavior

As a part of the aging structural integrity research for LWR components, the probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed in JAEA. This code evaluates the conditional probabilities of crack initiation and fracture of a reactor pressure vessel (RPV) under transient conditions such as pressurized thermal shock (PTS). A case study on the effect of non-destructive examination performance was performed using PASCAL. The analysis results showed that one non-destr uctive examinat...
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Development of Probabilistic Fracture Mechanics Analysis Code PASCAL For Reactor Pressure Vessel Considering Non-Destructive Examination

Abstract To assure the structural integrity of a reactor pressure vessel (RPV) is known as one of the critical issues to maintain the safe long-term operation of a nuclear power plant. In Japan, the assessment meth ods for RPV integrity, stipulated in the codes and standards, have been endorsed by the regulatory body. Authors have initiated extensive research on the improvement of structural integrity assessment methods of RP Vs. In this paper, we describe some research results obtained from the first-year...
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Study of System Safety Evaluation on LTO of National ProjectStructural Integrity Assessment of Reactor Pressure Vessels

To assure the structural integrity of a reactor pressure vessel (RPV) is known as one of the critical issu es to maintain the safe long-term operation of a nuclear power plant. In Japan, the assessment methods for RPV integrity, stipulated in the codes and standards, have been endorsed by the regulatory body. Authors h ave initiated extensive research on the improvement of structural integrity assessment methods of RPVs. I this paper, we describe some research results obtained from the second-year activity...
英字タイトル:
Study of System Safety Evaluation on LTO of National Project Structural Integrity Assessment of Reactor Pressure Vessels