Development of an In-Situ Method for Cable Condition Monitoring in Nuclear Power Plants

In the U.S., almost all the 104 operating commercial nuclear power plants have applied or plan to apply for license renewal, many of which have recently received approval. This has given rise to questions about the aging of structures, systems, and components (SSCs) that are important to plant safety and longevity. Recently, many national laboratories and agencies, including the Nuclear Regulatory Commission, have identified the aging of cable insulation materials (i.e. polymers) as an important issue to the safe operation of a plant. Although individual cables can be replaced, a wholesale replacement is cost-prohibitive and not a practical aging management strategy. As a response to this need, plants will begin to implement cable aging management programs to assess the health and performance of cables, especially those used for safety-related applications. However, currently available cable testing techniques are either destructive or focus primarily on the conductor. Of particular interest to the industry is a non-destructive method that offers in-situ testing capabilities to assess the aging condition of cable polymer materials. As such, the goal of this project is to adapt an in-situ electrical testing technique, known as Frequency Domain Reflectometry (FDR), for this application. The proposed Phase I project, AMS will evaluate the effectiveness of FDR to identify the aging condition of nuclear power plant cables. This will be accomplished through extensive laboratory testing involving thermal aging of polymer materials and a comparison of FDR results and Elongation at Break, the industry standard for health assessment of polymer materials. The result of the Phase I will be a prototype design of an FDR system, including both hardware and software, to be used in a cable aging management program. A Phase II project to be proposed later will develop a commercial FDR system for nuclear power plants. Commercial Applications and Other Benefits: Successful commercialization of this product will result in improved safety of nuclear power plants through accurate health and aging assessment of cable polymer materials. Applications include insulation degradation detection, hot spot detection, and conductor/connector problems.