High-Resolution Ultra-Wideband Reflectometry NDE for Cables in Nuclear Power Plants

Electrical cable integrity is critical for safe and continuous operation of nuclear power plants (NPPs). Cable jackets, electrical insulation, and junction points degrades rapidly with age, temperature, radiation, and other environmental factors in NPPs. Maintenance of the aging wiring network in NPP however has some technical challenges and among the most difficult to diagnose technical problems are those that are intermittent, ones that occur only during a particular set of environmental and operational conditions. For example, cable damages can result from all or one of the cable cores being severed, due to damage or erosion that can lead to arcing and or fire. These issues are rarely detected until they develop into a full fault, causing a service outage and possible safety risk. On the other hand, the NRC is proposing cutting back the frequency and scope of inspections at the country's nuclear reactors, in part to reduce costs and make nuclear energy more economically viable. Hence an automated real-time monitoring is needed with the capability to see what is happening within the infrastructure while operational -- without interfering with the operation of the NPP activities. This phase I SBIR will develop and demonstrate a novel next generation High-Resolution Ultra-wideband Time Domain Reflectometry (HR-UWB-TDR) technique that is able to continuously monitor NPP cables on live wires. While conventional time domain reflectometry (TDR) methods have been proven to be useful, in general current methods lack resolution and sensitivity required for cable multipath, junction and background noise interference effects. The proposed technique will be effective to address intermittent cable failures while the NPP is in operation and would reduce the time and extent of annual inspections significantly. This effort will focus on the development of an online (live) cable monitoring method for aging cables in NPPs without interference with NPP’s operation and activities. The applications and public benefits of this project can be significant for in-situ nondestructive evaluation (NDE) of live cables. The HR-UWB-TDR can be used in aerospace industry, trains and subways, as well as construction industry. The enabling technology resulting from this project will allow widespread acceptance of localized cable integrity detection in factories and warehouses also. This cable NDE capability will not only advance instrumentation for the public domain and industry but will also benefit the technology industry. Technology experiments can be conducted more effectively with high precision, robust, and stable calibrations.