Ultrasonic Inspection of Nuclear Power Plant Low Pressure Turbine Disk

The catastrophic failure of a low pressure (LP) turbine disk because of SCC in the keyway at the Hinckley Point nuclear power station in the United Kingdom in 1969 and the first discovery of stress corrosion crack (SCC) in the blade attachment region of nuclear LP turbine disks around the late 70's, industry concern with regard to this problem has increased significantly. These concerns were corroborated by an Electric Power Research Institute (EPRI) survey of U.S. nuclear and fossil utilities in 1995 which reported a significant increase in the incidence of rim cracking compared with an earlier EPRI survey in 1980. Data collected by EPRI through 1995 from nuclear utilities, revealed LP rim attachment cracking in 41 of 109 operating units in the U.S. The cracking mechanism reported was predominantly SCC with a few instances of corrosion fatigue and high cycle fatigue