Studying the influence of long-term operation on mediumvoltage (MV) cable and associated accessoriesperformance is an ongoing process. In the many yearscollecting operating experience at nuclear power plants(NPPs), including at those plants licensed for extendedoperation, it has been found that extruded polymercabling and accessories can be susceptible to degradationwhich in some cases cannot be easily or accuratelyinspected to assess reliability.NPPs have specific nuclear regulatory commitments toestablish programmatic ways to appropriately assess andmaintain aging management of medium voltage cablesand accessories. This paper provides practical NPPexperience, methods, and examples of maintaining acomprehensive test methodology that prevents emergentcable replacement and/or unplanned outages. The twovivid examples depicted in this paper discuss this matureMV cable testing program based on a combination ofcomplementary test methods that enable NPPs to:1. Maximize sensitivity to a broad range of defects2. Minimize the risk of ‘false positive' and ‘falsenegative’ diagnostic results3. Provide high confidence in engineering judgmentsand decisions.The combination of testing techniques provides a solidtechnical basis to support robust ‘Fitness for Service'decisions. The condition monitoring data can be used toidentify time-related deterioration trends before theyaffect cable performance. The overall approach allowsNPPs to make risk-informed and planned decisions ontargeted replacement/repair and to address deficienciesto maintain reliable electrical systems.
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