SEDL / STP / STP1049-EB / STP24065S

Environmental Acceleration of Fatigue Crack Growth in Reactor Pressure Vessel Materials and Environments

Van Der Sluys, WA
Technical advisor and senior research engineer, The Babcock & Wilcox Company, Alliance, OH

Emanuelson, RH
Technical advisor and senior research engineer, The Babcock & Wilcox Company, Alliance, OH

Pages: 19    Published: Jan 1990

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Abstract

This paper presents the results of experiments to determine which variables have the most effect on environmentally assisted cracking (EAC) of reactor pressure vessel steels. Four heats of SA508 and three heats of SA533 were studied in 288°C pressurized water reactor, light water reactor, and boiling water reactor environments. The sulfur content of these materials ranged from 0.004 to 0.025%. The most important variable was found to be the sulfur content and sulfur morphology of the material. A material with a bulk sulfur content greater than 0.010% may be susceptible to EAC. The loading frequency was found to be an important variable. Minor effects of EAC were attributed to the load ratio, ΔK level, and oxygen content of the environment. An experimental method to introduce sulfur directly to the crack tip is described. A time-based method of data interpretation is discussed.