Aging Mechanisms and Monitoring of Cable Polymers

Bowler, Nicola; Liu, Shuaishuai

doi:10.36001/ijphm.2015.v6i3.2287

Cited by 28 publications

(18 citation statements)

References 51 publications

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“…Thus, molecular structure changes arise due to chemical reactions. Besides the oxidation process, cross-linking, and chain-scission are two opposite reactions that may occur within the same polymer simultaneously [ 15 ]. As a result of these reactions, polar molecules and groups are generated, which respond to the external field through orientation.…”

Section: Discussionmentioning

confidence: 99%

“…However, the EaB test is naturally destructive, and it requires samples removal; thus, it is not practical for on-site testing [2,5,10,26]. Therefore, non-destructive electrical-based condition monitoring techniques have been the focus of scientific interest, such as dielectric spectroscopy, return voltage measurement, and the polarization-depolarization current method [8][9][10]14,15,19,20,[26][27][28][29][30]. These techniques have been successfully adapted to various insulation systems [2,5,26,30].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the various aging factors, the composition of used jacket and insulating materials also play an important role in aging. The insulation of NPP cables is mainly based on polymers such as cross-linked polyethylene (XLPE), ethylene-propylene rubber (EPR), and chlorosulphonated polyethylene (CSPE) [ 13 , 15 ]. Most of the polymers used in cables contain several additives to enhance the chemical, physical, and electrical properties [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…These additives include antioxidants, flame retardants, coloring agents, fillers and curing agents, plasticizers, initiators, stabilizers, and other chemicals [ 17 , 18 ]. Additives have a pivotal role in the physicochemical and degradation characteristics of cable materials [ 15 , 16 , 19 , 20 ]; therefore, it is crucial that the formulation of the cable material is traceable and documented, particularly for critical applications such as NPPs [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Aging Mechanisms and Non-Destructive Aging Indicators of XLPE/CSPE Unshielded LV Nuclear Power Cables Subjected to Simultaneous Radiation-Mechanical Aging

2021

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Low-voltage cable systems in nuclear power plants are key components that have a crucial role in the safe operation of nuclear facilities. Thus, the aging management of cable systems is of utmost importance as they cannot easily or economically be replaced or upgraded. Therefore, there is a continuous need to develop reliable non-destructive condition monitoring techniques, mostly based on the measurement of the dielectric properties of cable insulation. This paper introduces the changing of dielectric and mechanical properties of XLPE insulated and CSPE jacketed unshielded low-voltage nuclear power plant power cable in case of simultaneous mechanical and radiation aging. The cable samples were bent and exposed to 400 kGy gamma irradiation with a 0.5 kGy/hr dose rate. Dielectric response (real and imaginary permittivity) in the 0.1 Hz−1 kHz frequency range, extended voltage response (EVR), and the Shore D hardness test techniques were measured to track aging. The electrical and mechanical parameters have increased monotonically with aging, except the imaginary permittivity, which increased only at frequencies higher than 10 Hz. Furthermore, different quantities were deducted based on the frequency and permittivity data. The electrical parameters and deducted quantities correlation with aging and mechanical parameters were investigated. Since the deducted quantities and the electrical parameters are strongly correlated with absorbed dose and mechanical properties, the electrical measurements can be applied as a non-destructive aging indicator for XLPE/CSPE unshielded low-voltage nuclear power cables.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Aging Mechanisms and Non-Destructive Aging Indicators of XLPE/CSPE Unshielded LV Nuclear Power Cables Subjected to Simultaneous Radiation-Mechanical Aging

2021

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“…However, due to the extensive application of such cables, aging conditions are not constant throughout the cable length, leading to a difficult a priori aging management of these cables [1], [6]. In point of fact, they are subjected to different aging stressors depending on the zone of the NPP they are placed, i.e., high temperatures, radiation, moisture and different mechanical stresses [6][7][8][9][10][11]. For this reason, a continuous monitoring of the cable status is strongly recommended in order to prevent unexpected cable failure.…”

Section: Introductionmentioning

confidence: 99%

Aging Modeling of Low-Voltage Cables Subjected to Radio-Chemical Aging

Suraci

Fabiani

2021

IEEE Access

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This article presents the development and application of a modelling approach based on quantities obtained from mechanical and electrical tests to assess the aging of low voltage cable insulation for nuclear applications. In order to obtain experimental data needed for the establishing of the models, accelerated aging is performed on coaxial cables. The first part of this paper focuses on the development of a predictive modelling for mechanical properties; this allows the evaluation of the Dose to Equivalent Damage (DED) as a function of the aging stress (dose rate). However, the use of mechanical tests for cable aging assessment presents some problems, being such tests destructive for the insulation and potentially affected by local defects. The novelty of this work lays on the introduction of a new model, allowing the definition of the end-of-life point in terms of electrical non-destructive tests. The second part of this article presents the development of aging modelling of cable insulation and correlation with experimental data obtained at different stresses, which allow the estimation of the expected life of the cable under test to be derived from diagnostic measurements of electrical properties like, e.g, tan. Finally, the application of the proposed life model to two typical real-condition nuclear environments is presented and discussed.INDEX TERMS Modelling of insulations, LV cables, Nuclear cables, radio-chemical aging, predictive modeling, cable life modeling, polymer aging, extruded cables.

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A recent review on ventilation and cooling of underground high-voltage cable tunnels

Elsaid,

Zahran,

Abdel Moneim

et al. 2024

J Therm Anal Calorim

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The rapid progression in the current economic cities and the push for societal advancement are driving the development of tall, slim structures that require underground utility tunnels. These tunnels, known as underground services tunnels, are built beneath urban areas and house a variety of main pipelines for gas, heating, and electricity. They serve as underground walkways, high-voltage lines, drainage systems, and water supply networks. The construction of these underground tunnels is essential for facilitating the future growth of buildings and infrastructure without disrupting the streets where utilities were traditionally located in older city layouts. The increase of the quantity of deeply buried extra-long tunnels has increased quickly, leading to geothermal hazards emerging as a significant issue in engineering projects. This research has studied many approaches for ventilation or cooling of underground cable tunnels. Approximately 90% of the utilized techniques consisted of air ventilation, encompassing mechanical, natural, or a combination of both approaches. It is important to consider that this particular method is more commonly employed in regions with higher weather conditions similar to Egypt. Nonetheless, this approach efficiently sustains satisfactory indoor temperatures surrounding cables, guaranteeing that they stay below 40 °C. Nevertheless, in the particular climate region of Egypt, where outdoor temperatures can soar more to 40 °C, it became crucial to subject the air to cooling before it is supplied into the tunnel. The impact of the mist (FOG) system on tunnel cooling was also examined. However, it has been discovered that the humidity levels in tunnels rise excessively, despite the high initial cost involved, particularly in lengthy tunnels. Consequently, it is not regarded as a viable method for cooling cables. Its sole application lies in serving as a fire suppression system for cable tunnels. Approximately 10% of the conducted research employed water cooling, which involved circulating cold water through pipes located next to the cables in rows. As a result of convection heat transfer, the air surrounding the cables in the tunnel is effectively cooled. It was found from this study that mechanical air cooling (ventilation) is the most efficient way of dealing with heat dissipated from cables by convection inside tunnels.

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Aging Mechanisms and Monitoring of Cable Polymers

Cited by 28 publications

References 51 publications

Aging Mechanisms and Non-Destructive Aging Indicators of XLPE/CSPE Unshielded LV Nuclear Power Cables Subjected to Simultaneous Radiation-Mechanical Aging

Aging Mechanisms and Non-Destructive Aging Indicators of XLPE/CSPE Unshielded LV Nuclear Power Cables Subjected to Simultaneous Radiation-Mechanical Aging

Aging Modeling of Low-Voltage Cables Subjected to Radio-Chemical Aging

A recent review on ventilation and cooling of underground high-voltage cable tunnels

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