This milestone report presents an update on the state-of-the-art review and research being conducted to identify key indicators of cable aging at nuclear power plants (NPPs), and devise in-situ measurement techniques that are sensitive to these key indicators. The motivation for this study stems from the need to address open questions related to nondestructive evaluation (NDE) of aging cables for degradation detection and estimation of condition-based remaining service life. These questions arise within the context of a second round of license extension for NPPs that would extend the operating license from 60 to 80 years. Within the introduction, a review of recent published U.S. and international research and guidance for cable aging management programs including NDE technologies is provided. As with any "state-of-the-art" report, the observations are deemed accurate as of the publication date but cannot anticipate evolution of the technology. Moreover, readers are advised that research and development of cable NDE technology is an ongoing issue of global concern.Cable safety factors offer significant margin for normal operation and consequently most cables can be expected to perform satisfactorily under normal loads. Cables are inherently tested as part of the regular system tests that are periodically performed on nuclear plant systems and active components. As emphasized in Regulatory Guide 1.128, the cable aging management program focuses on the ability of a cable to withstand extreme stresses such as in a design-basis event (DBE) that may not be addressed with normal system tests. Degradation of the electrical insulation and other cable components are key issues that are likely to affect the ability of the currently installed cables to operate safely and reliably under a DBE for another 20 to 40 years beyond the initial qualified operating life. With more than 1000 km of power, control, instrumentation, and other cables typically found in a NPP, it would be a daunting undertaking to inspect all of the cables. Practical guidelines, however, have been developed and are evolving that offer a manageable approach to sampling and screening cables based on accessibility, risk, history, and other factors. Moreover, the range of cables and conditions plus today's state of the art does not support a single test to assure the cable's function. Rather, a range of testing tools must be applied to manage the cable aging concerns and assure that degraded cables are repaired or replaced prior to the end of their safe operating life. Cable aging management program recommendations include a database of cables selected for test and trending including the required appropriate cable test based on accessibility, risk, and environment. Such tests include bulk electrical characteristic measurements that can be made from the cable ends and, in some cases, locate the weak portion of the cable as well as local tests to confirm insulation condition and provide guidance to predict remaining available safe life.The Pacific Northwest Nat...

Doped HfO2 has become a promising candidate for non-volatile memory devices since it can be easily integrated into existing CMOS technology. Many dopants like Y, Gd, and Sr have been investigated for the stabilization of ferroelectric HfO2. Here, we report the fabrication of capacitors comprising ferroelectric HfO2 metal-insulator-metal structures with TiN bottom and top electrodes using the dopant Lu. Amorphous 5% Lu doped HfO2 was deposited by pulsed laser deposition and afterwards annealed to achieve the ferroelectric, orthorhombic phase (space group Pbc21). The polarization of the layers was confirmed by capacitance-voltage, polarization-voltage, and current-voltage measurements. Depending on the anneal temperature, the remanent polarization changes and the initial state of the oxide varies. The layer exhibits initially a pinched hysteresis up to an annealing temperature of 600 °C and an unpinched hysteresis at 700 °C. The maximum polarization is about 11 μC/cm2 which is measured after 104 cycles and stable up to 106 cycles. The influence of the layer thickness on the oxide properties is investigated for 10–40 nm thick HfLuO; however, a thickness dependence of the ferroelectric properties is not observed.

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Power and instrumentation cables play a crucial role in the safe operation of Nuclear Power Plants (NPPs). Thermal and other stressors present in the reactor environment cause the cable materials to degrade. In this work, dielectric and mechanical properties of cable insulation and jacket materials are studied as they are thermally aged, supporting development of non-destructive evaluation sensors for monitoring cable aging. Materials selected for this study are found in certain types of single-core unshielded power cables. These utilize ethylene propylene rubber (EPR)-based insulation material and chlorinated polyethylene (CPE)-based jacket material. Flat mats of these materials were obtained from the cable manufacturer and thermally aged at 140 °C in an air-circulating oven. Elongation-at-break was measured on tensile specimens stamped from the aged mats, and dielectric properties were measured from 100 Hz to 100 kHz using a parallel plate capacitor and precision LCR meter. In the case of aged EPR-based materials, rapid decrease in elongation at break indicating end of useful life was accompanied by a significant increase in dissipation factor, D, measured at 100 kHz. Capacitive measurement of D shows promise, therefore, as a non-destructive indicator of corresponding mechanical property changes in thermally-aged EPR-based insulation materials.