Probabilistic fracture mechanics of irradiation assisted stress corrosion cracking in stainless steels

Abstract A probabilistic fracture mechanics (PFM) analysis code, PASCAL-SP, has been developed by Japan Atomic Energy Agency (JAEA) to evaluate the failure probability of piping within nuclear power plants considering aged-related degradations such as stress corrosion cracking and fatigue for both pressurized water reactor and boiling water reactor environments. To strengthen the applicability of PASCAL-SP, a benchmarking study is being performed with a PFM analysis code, xLPR, which has been developed by U.S.NRC in collaboration with EPRI. In this benchmarking study, deterministic and probabilistic analyses are undertaken on primary water stress corrosion cracking using the common analysis conditions. A deterministic analysis on the weld residual stress distributions is also considered. These analyses are carried out by U.S.NRC and JAEA independently using their own codes. Currently, the deterministic analyses by both xLPR and PASCAL-SP codes have been finished and probabilistic analyses are underway. This paper presents the details of conditions and comparisons of the results between the two aforementioned codes for the deterministic analyses. Both codes were found to provide almost the same results including the values of stress intensity factor. The conditions and results of the probabilistic analysis obtained from PASCAL-SP are also discussed.

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Benchmarking Study on Probabilistic Fracture Mechanics Analysis Codes xLPR and PASCAL-SP Considering Primary Water Stress Corrosion Cracking

10.1115/pvp2021-61202 ◽

2021 ◽

Author(s):

Akihiro Mano ◽

Jinya Katsuyama ◽

Yinsheng Li

Keyword(s):

Water Stress ◽

Fracture Mechanics ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Structural Integrity ◽

Corrosion Cracking ◽

Pressurized Water ◽

Probabilistic Fracture Mechanics ◽

Primary Water ◽

Failure Probabilities

Abstract Probabilistic fracture mechanics (PFM) is expected as a more rational methodology for the structural integrity assessments of nuclear power components because it can consider the inherent probabilistic distributions of various influencing factors and quantitatively evaluate the failure probabilities of the components. The Japan Atomic Energy Agency (JAEA) has developed a PFM analysis code, PASCAL-SP, to evaluate the failure probabilities of piping caused by aging degradation mechanisms, such as fatigue and stress corrosion cracking in the environments of both pressurized water and boiling water reactors. To improve confidence in the analysis results obtained from PASCAL-SP, a benchmarking study was conducted together with the PFM analysis code, xLPR, which was developed jointly by the U.S. Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute. The benchmarking study was composed of deterministic and probabilistic analyses related to primary water stress corrosion cracking in a dissimilar metal weld joint in a pressurized water reactor surge line. The analyses were conducted independently by NRC staff and JAEA using their own codes and under common analysis conditions. In the present paper, the analysis conditions for the deterministic and probabilistic analyses are described in detail, and the analysis results obtained from the xLPR and PASCAL-SP codes are presented. It was confirmed that the analysis results obtained from the two codes were in good agreement.

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Application of Failure Event Data to Benchmark Probabilistic Fracture Mechanics Computer Codes

Volume 6: Materials and Fabrication ◽

10.1115/pvp2007-26373 ◽

2007 ◽

Author(s):

F. A. Simonen ◽

S. R. Gosselin ◽

B. O. Y. Lydell ◽

D. L. Rudland ◽

G. M. Wilkowski

Keyword(s):

Fracture Mechanics ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Nuclear Power ◽

Operating Experience ◽

Corrosion Cracking ◽

Operating Conditions ◽

Intergranular Stress Corrosion ◽

Probabilistic Fracture Mechanics ◽

Computer Codes

This paper describes an application of data on cracking, leak and rupture events from nuclear power plant operating experience to estimate failure frequencies for piping components that had been previously evaluated using the PROLOCA and PRAISE probabilistic fracture mechanics (PFM) computer codes. The calculations had addressed the failure mechanisms of stress corrosion cracking, intergranular stress corrosion cracking and fatigue for materials and operating conditions that were known to have failed components. The first objective was to benchmark the calculations against field experience. A second objective was a review of uncertainties in the treatments of the data from observed failures and in the structural mechanics models. The database PIPExp-2006 was applied to estimate failure frequencies. Because the number of reported failure events was small, there were also statistical uncertainties in the estimates of frequencies. Comparisons of predicted and observed failure frequencies showed that PFM codes correctly predicted relatively high failure probabilities for components that had experienced field failures. However, the predicted frequencies tended to be significantly greater than those estimated from plant operating experience. A review of the PFM models and inputs to the models showed that uncertainties in the calculations were sufficiently large to explain the differences between the predicted and observed failure frequencies.

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Study on PWSCC Behaviors at Nickel-Based Alloy Welds Based on Weld Residual Stress Analysis and Probabilistic Fracture Mechanics

ASME 2010 Pressure Vessels and Piping Conference: Volume 1 ◽

10.1115/pvp2010-26028 ◽

2010 ◽

Cited By ~ 2

Author(s):

Makoto Udagawa ◽

Jinya Katsuyama ◽

Kunio Onizawa

Keyword(s):

Residual Stress ◽

Fracture Mechanics ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Corrosion Cracking ◽

Probabilistic Fracture Mechanics ◽

Crack Penetration ◽

Weld Residual Stress ◽

Primary Water ◽

Operating Stress

A number of cracks due to primary water stress corrosion cracking (PWSCC) in PWR and Ni-based alloys stress corrosion cracking (NiSCC) in BWR have been observed near Ni-based alloy welds. One of the causes of initiation and growth due to SCC is high tensile residual stress as well as operating stress. In this study, an analysis code, PASCAL-NP, for the PWSCC/NiSCC growth at the dissimilar metal welds based on probabilistic fracture mechanics (PFM) was developed. This PFM analysis code has a function of SCC growth calculation for some patterns of crack locations and orientations in a probabilistic manner. This code can also evaluate the failure probability of Ni-based alloy welds due to PWSCC/NiSCC. Using this code and results from welding simulations, case studies on PWSCC growth have been performed focusing on the location and orientation of PWSCC. Effects of the weld residual stress and scatter of PWSCC growth rate on the crack penetration such as leakage are shown in comparison with deterministic analyses.

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