An apparatus and a process for measuring rotor creep values for a monolithic rotor of an industrial gas turbine engine in order to determine when creep growth of the rotor has exceeded an allowable limit. One or more critical locations of the rotor are measured for real-time radius, and a CPU having rotor creep deflection model is used to compare the real-time data and determine if the rotor creep is within safe and allowable limits. If the creep is determined to exceed allowable values, then an alarm in initiated or engine shutdown occurs.