Remaining Useful Life Estimation of Electric Cables in Nuclear Power Plants

Electric cables help form the backbone of instrumentation and control (I&C) systems in nuclear power plants by providing power to electrical equipment and transmission paths for instrumentation signals used to perform safety functions and control plant operation. Operating experience in the existing fleet of nuclear reactors has shown that the number of cable failures increases with plant age resulting in plant transients, shutdowns, and in some cases, the loss of safety functions (NRC, 2012). As a result, cable condition monitoring and remaining useful life (RUL) estimation have become increasingly important in recent years, especially as many plants begin operation beyond their original licensing periods. To facilitate the understanding of cable aging mechanisms and degradation detection, the United States Department of Energy (DOE) and the Electric Power Research Institute (EPRI) developed the Cable Polymer Aging Database (CPAD). The CPAD provides a repository of test results from cable aging experiments performed by a number of research institutions and represents one of the most comprehensive sources of cable degradation data that is publically available (EPRI, 2002). This paper describes the process the authors used to select appropriate prognostic parameter(s), develop prognostic models, and estimate the RUL of nuclear power plant cables from the data contained in the CPAD.