Nonmandatory Appendix Y of ASME Section XI presents relationships for fatigue crack growth rates and stress corrosion crack growth rates for austenitic stainless steels, ferritic steels, and nickel alloys for use in analytical evaluations. These crack growth rate equations are needed to predict the crack growth rate for the applicable cracking mechanism, material, and environment. The cracking mechanisms addressed are fatigue in air, fatigue in water environments, stress corrosion cracking, and irradiation-assisted stress corrosion cracking. Boiling water reactor and pressurized water reactor water environments are included. Nonmandatory Appendix Y was introduced within the 2021 Edition of the ASME Boiler and Pressure Vessel Code as a consolidated repository for crack growth rate equations. A second objective of Appendix Y is to standardize the nomenclature, physical units, and figures associated with the various crack growth rate relations. Changes anticipated for the 2023 Edition include moving all crack growth rate provisions from other nonmandatory Section XI appendices (including Nonmandatory Appendices A and C) into Appendix Y. This paper describes the organization of the 2023 Edition of Appendix Y and documents the source of each equation. Also tabulated are the active Section XI Code Cases that include crack growth rate equations, as well as the most recent status of acceptance by the U.S. Nuclear Regulatory Commission.

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