Advanced Cable-Testing Techniques for Nuclear Power Plants

Cable condition monitoring involves a variety of testing or monitoring methods, none without limitations. Mechanical and chemical tests are only local in their effectiveness; they can miss problems in the untested cable. Electrical-cable-condition-monitoring tests - including insulation resistance tests, impedance measurements (such as the LCR test), and reflectometry or "cable radar" methods - make it possible to test entire cable circuits while they remain in operation. Impedance measurements enable the evaluation of cable condition factors such as dielectric absorption ratio, polarization index, quality factor, and dissipation factor. Several new electrical measurement methods, including time or frequency domain reflectometry, and a wireless microsensor technology called AgeAlert™, are showing promise as techniques for in situ monitoring of the nuclear power plant cable condition. The integration of all these methods and their combination with end-device testing methods represent a new application of cable condition monitoring that promises to provide the correlation between aging test results and the aging condition of in situ cables that individual methods by themselves do not provide.