Fatigue reliability design and assessment of reactor pressure vessel structures: Concepts and validation

Abstract

Traditional design approaches using safety factors are intended to account for uncertainties due to the lack of available data in engineering practice. However, the direct use of safety factor to represent uncertainties often causes conservative results, and it is not intuitive to describe the reliability of these structures through safety factor. To deal with the issue, this research revisits the initial consideration and intent of the safety factor for static strength and adjustment factor for fatigue design curve in the ASME code. Three conversion models applying to reactor pressure vessel (RPV) materials are proposed on basis of the stress–strength, load–life and strength–damage interference theories, which elaborate the relationship between safety/adjustment factors and structural reliability. The dispersion of strength and fatigue life is quantified, and then implemented to elaborate safety and adjustment factors with reliability respectively, which verifies the validity of safety assessment methods in the ASME code. Moreover, the safety/adjustment factor design under required reliability level is achieved, has the advantages of intuitiveness and convenience, which provides a reference for the reliability and safety design of RPV.