Operating experience with 1100 MW wet steam turbines in a nuclear power plant

The American Electric Power Company, one of the largest U.S. electric utilities, has over ten years of experience in the successful operation of two 1100-MW wet steam turbines. The two machines, each designed by a different manufacturer, are in base-load service in a Pressurized Water Reactor nuclear power plant. This paper presents the highlights of that experience, covering turbine reliability, performance, inspection and operation. The results of a full-scale ASME code performance test of one of the turbines are discussed. Moisture erosion, typical in wet steam cycles, has been found in the turbine steam path and piping systems. Problems that occurred early in the life of the external moisture separators and reheaters, and how these problems were resolved, are discussed. The more recent industry-wide problem of disc cracking of built-up rotors and the mitigation of that problem through periodic inspections and a change in rotor design are also covered. (author)