Light Water Reactor Sustainability (LWRS) Program ? Non-Destructive Evaluation (NDE) R&D Roadmap for Determining Remaining Useful Life of Aging Cables in Nuclear Power Plants

Abstract

universities, commercial NDE service vendors and cable manufacturers, and the Electric Power Research Institute (EPRI).The motivation for the R&D roadmap comes from the need to address the aging management of incontainment cables at nuclear power plants (NPPs). The most important criteria for cable performance is its ability to withstand a design basis accident. With nearly 1000 km of power, control, instrumentation, and other cables typically found in an NPP, it would be a significant undertaking to inspect all of the cables. Degradation of the cable jacket, electrical insulation, and other cable components is a key issue that is likely to affect the ability of the currently-installed cables to operate safely and reliably for another 20 to 40 years beyond the initial operating life. The development of one or more NDE techniques and models that could assist in determining the remaining life expectancy of cables or their current degradation state would be of significant interest. The ability to non-destructively determine material and electrical properties of cable jackets and insulation without disturbing the cables or connections is essential.The major emphasis of the workshop focused on the chemical changes in the material caused by the environment (thermal, radiation, and moisture, its relationship to mechanical, physical, and electrical property changes of dielectric materials used in cable insulation and jackets and the current state-of-theart in NDE techniques for detecting aging and degradation of cables. The only current technique accepted by industry to measure cable elasticity (the gold standard for determining cable insulation degradation) is the indentation measurement. All other NDE techniques are used to find flaws in the cable and do not provide information to determine the current health or life expectancy.Currently, there is no single NDE technique that can satisfy all of the requirements needed for making a life expectancy determination, but a wide range of methods have been evaluated for use in NPPs as a part of a continuous evaluation program. The commonly used methods are indentation and visual inspection, but these are only suitable for easily accessible cables. Several NDE methodologies utilizing electrical techniques are in use today for flaw detection but there are none that can predict the life of a cable.The results from the workshop identified three key areas of importance:1. Determine key indicators of cable aging that correlate with measureable changes in material properties at the macroscopic scale.iv 2. Advance state-of-the-art in current cable NDE methods and develop new and transformational NDE methods to enable in-situ cable condition measurements that can be used to assess remaining life expectancy. The data for these developments would be collected from samples generated in laboratory cable aging experiments as well as field samples.3. Develop models for predicting remaining useful life of cables based on condition indices. The data for these models would come from existing d...

Interdigital Capacitance Local Non-Destructive Examination of Nuclear Power Plant Cable for Aging Management Programs

“…The overall objectives of this program are to develop the technical basis for assessing existing and emerging non-destructive evaluation (NDE) methods for cable insulation aging and degradation in nuclear power plants (NPPs). In July 2012, a workshop (Simmons et al 2012) was held to lay the groundwork for a research and development roadmap to address aging cable management in NPPs, including methods for nondestructively measuring the condition of aging cables. This roadmap addresses the overall gaps that were identified at that workshop using a phased approach and covering three areas:…”

Compton imaging tomography for one-sided access NDE of nuclear power plant structures, systems, and components

“…CIT-based tools can be developed and optimized as versatile tools for NDE of aging NPP structures, systems, and components (SSCs) in situ or during scheduled reactor maintenance interruptions, to detect NPP cabling degradation, welding defects and pipe wall degradation and cracking, and also early material fatigue and stress cracking [12,13]. Due to the nondestructive nature of the evaluation and fast scanning speed, most of NPP cables and other structures can be fully characterized continuously during normal NPP operation and completely independently of NPP maintenance periods, thereby improving the probability of detecting critical degradation.…”

“…Development and qualification of new nuclear fuels and materials [12][13][14][15] require specific testing of fuels under short bursts of intense high-power radiation into a reactor core. Such testing is called "transient testing."…”

Determining Remaining Useful Life of Aging Cables in Nuclear Power Plants ? Interim Study FY13

“…Instrument calibration in both cases uses materials with known acoustic properties (such as acrylic or glass). (Simmons et al 2012) proved to be valuable resources in identifying the latest research applicable to electrical measurements on cables. From these reports, Table 3.1 identifies electrical measurements and their advantages and disadvantages.…”

“…In July 2012, a workshop (Simmons et al 2012) was held to lay the groundwork for a research and development roadmap to address aging cable management in NPPs. This workshop brought together subject matter experts from the U.S. Nuclear Regulatory Commission (NRC), U.S. Department of Energy (DOE) national laboratories, the Electric Power Research Institute (EPRI), universities, and cable manufacturers and inspectors.…”