scope:

The fatigue crack growth behavior of ferritic materials can be greatly affected by exposure to light-water reactor environments. Some combinations of material and environment are susceptible to enhanced crack growth rates, referred to herein as Environmentally Assisted Cracking (EAC). Susceptibility to EAC during fatigue cycling is controlled by (1) metallurgical factors such as material chemistry, particularly sulfur content and morphology, (2) environmental factors such as water chemistry and temperature, and (3) factors affecting crack-tip properties such as Electrochemical Corrosion Potential (ECP), water flow rate as it flushes the crack-tip region, and crack-face surface conditions as they affect mass transport of particles into and out of the crack-tip region. This Case provides criteria for determining the susceptibility of ferritic materials to EAC, reference fatigue crack growth rate behavior for material susceptible to EAC, and reference fatigue crack growth rate behavior for material not susceptible to EAC.