Steam turbines of nuclear plants, mainly those manufactured in the 1970s, are more subjected to stress corrosion cracking (SCC) than to degradation due to fatigue. In few years of operation, the turbine disks can develop cracks that grow with time. The main reasons for the SCC are the high stresses together with a susceptible material and an aggressive environment. All these factors exist in turbine components. The analysis of this problem assumes that the crack geometry is determined from the results of ultrasonic nondestructive tests. One of the most limiting locations for the SCC is the keyway area that connects the disk to the rotor of a low-pressure turbine, the part which may be subject to the high moisture of steam. The results show that with an adequate inspection strategy it is possible to follow the evolution of the defect and assure the turbine’s integrity and the reliable operation of the plant.