Replacing turbine I&C systems in nuclear power plants

Steam turbines can attain operating lives of up to fifty years if they are maintained properly. Good care and maintenance can keep turbine control systems operational for more than twenty years, but never for the entire operating life of a turbine. When replacement becomes necessary, it is only logical to upgrade the system to a higher standard of availability and safety. Experience accumulated in projects of this kind is summarized in this article. An outline is given of the ideas to be considered in preparation of a successful upgrade of a turbine control system. Above all, it is shown that there is not one redundancy concept which will fit all cases. Incorporating all technical and commercial criteria in the project specification ultimately will result in a successful replacement project. Practical cases demonstrating the ideas considered can be found in the nuclear power plant projects of Kuosheng, Taiwan, and Muhleberg and Beznau, Switzerland, among others.