STP700

    A Stability Analysis of Circumferential Cracks for Reactor Piping Systems

    Published: Jan 1980


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    Abstract

    The high ductility and toughness of the stainless steel reactor piping system have made it virtually certain not to experience unstable crack extension. The present study attempts to provide theoretical assurance that the piping system will not suffer unstable crack extension even if severe circumferential cracking should occur. The analysis is based on the tearing instability concept and the tearing modulus criterion. Simplifications are conservatively made to facilitate the complicated analysis. The results are presented parametrically in graphical forms for convenience of general use. An application to a specific example is also discussed.

    The results indicate that the ratio, L/R, is of major importance in consideration of crack stability, where L is the length of the pipe between supports and R is the radius of the pipe. It is shown that unstable crack extension would not occur in stainless steel piping systems designed in accordance with the American Society of Mechanical Engineers' (ASME) code even if severe circumferential flaws were present, provided that the values of L/R are less than about 200. Since the values of L/R for boiling water reactor (BWR) stainless steel piping systems are generally much smaller, large margins against unstable fracture are assured for these systems. When L/R exceeds 200, a more detailed analysis would be necessary to demonstrate crack stability.

    Keywords:

    stainless steels, reactor piping systems, stress corrosion cracking, J-integral, J-R curves, tearing instability, tearing modulus (, T, ), fractures (materials), crack propagation


    Author Information:

    Tada, H
    Senior research associate and professor of mechanics, Center for Fracture Mechanics, Washington University, St. Louis, Mo.

    Paris, PC
    Senior research associate and professor of mechanics, Center for Fracture Mechanics, Washington University, St. Louis, Mo.

    Gamble, RM
    Section leader, Materials Integrity Section, Materials Engineering Branch, Division of Systems Safety, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, D.C.,


    Paper ID: STP36977S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP36977S


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