United States Nuclear Regulatory Commission - Protecting People and the Environment

Analysis of Crack Initiation and Growth in the High Level Vibration Test at Tadotsu (NUREG/CR-6078, BNL-NUREG-52383)

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Publication Information

Manuscript Completed: August 1993
Date Published: August 1993

Prepared by:
M. K. Kassir
Y. J. Park
C. H. Hofmayer
K. K. Bandyopadhyay
S. Shteyngart
Brookhaven National Laboratory
Upton, NY 11973

Prepared for:
Division of Engineering
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC FIN Ll381

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Abstract

The High Level Vibration Test data are used to assess the accuracy and usefulness of current engineering methodologies for predicting crack initiation and growth in a cast stainless steel pipe elbow under complex, large amplitude loading. The data were obtained by testing at room temperature a large scale modified model of one loop of a PWR primary coolant system at the Tadotsu Engineering Laboratory in Japan. Fatigue crack initiation time is reasonably predicted by applying a modified local strain approach (Coffin-Mason-Goodman equation) in conjunction with Miner's rule of cumulative damage. Three fracture mechanics methodologies are applied to investigate the crack growth behavior observed in the hot leg of the model. These are: the ΔK methodology (Paris law), ΔJ concepts and a recently developed limit load stress-range criterion. The report includes a discussion on the pros and cons of the analysis involved in each of the methods, the role played by the key parameters influencing the formulation and a comparison of the results with the actual crack growth behavior observed in the vibration test program. Some conclusions and recommendations for improvement of the methodologies are also provided.

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