Nuclear Power Plant Instrumentation and Control Cable Prognostics Using Indenter Modulus Measurements

Abstract

As the fleet of nuclear power plants (NPPs) approach their1 original qualified life (typically 40 years) and operators seek license extensions, regulators require assurance that they can continue to operate safely in the decades to come. Some of the most important, yet often overlooked components, are the cables that provide the signal paths for instrumentation and control (I&C) systems used to ensure safe and efficient operation of NPPs.In response to this, the authors explore the use of expanding indenter modulus (IM), an industry-accepted technique for cable condition monitoring, into a prognostic tool for predicting the remaining useful life (RUL) of I&C cables. Not only is this technique non-destructive, but it can be performed while NPP cables are in service, thus making it practical for adoption into existing cable condition monitoring programs. In this paper, the authors describe an accelerated aging cable test bed used to acquire several types of measurement parameters as cables age. Additionally, practical techniques are described in which simple IM measurements can be leveraged for condition monitoring and RUL estimation.Error analysis indicates the proposed method is superior to conventional RUL estimation techniques, such as simple trending and curve fitting. The authors demonstrate that using IM can potentially provide a non-destructive, in-situ estimation of RUL for I&C cables. As described in this paper, the IM data clearly shows trends as a function of cable age, and shows promising performance for RUL estimation especially compared with conventional techniques.

Demonstration of a Response Time Based Remaining Useful Life (RUL) Prediction for Software Systems

“…Software reliability growth models assume that reliability growth is due to bugs being removed. The RUL of software is impacted by future enhancement requests or the addition of new features that may not generate any faults 4 . Reliability is a measurement of performance attributed to faults and the RUL of software is attributed to performance that may or may not be attributed to faults.…”

“…Data on degradation parameters is used to regress selected mathematical model(s) and to extrapolate the model(s) to a pre-determined failure threshold. The difference between the time (or other appropriate usage parameters) at the current point and the point at which the extrapolated behavior exceeds the failure threshold is the estimated RUL [4]. Prognostics is focused on predicting the time (or other appropriate usage parameters) at which a system or a component will no longer perform its intended function.…”

Comparison of Mechanical and Low-Frequency Dielectric Properties of Thermally and Thermo-Mechanically Aged Low Voltage CSPE/XLPE Nuclear Power Plant Cables

“…The mechanical properties were measured using Shore D hardness, which is a simplified indenter measurement. The indenter type measurements are widely and effectively used for the aging monitoring of NPP cables [32][33][34]. The results of the thermally and thermo-mechanically aged groups were compared to determine the degradation caused by combined stress over the simple thermal aging.…”