Abstract

The aging of electrical cables has been the subject of substantial research and development (R&D) projects performed by national and international laboratories, universities, and private organizations for many years. This R&D was conducted to develop guidance, equipment, and techniques to support aging management of in-service cables in industrial facilities such as nuclear power plants, research reactors, waste facilities, and fuel fabrication plants. Through these research efforts, condition monitoring technologies have been developed that can determine the severity of age-related degradation that occurs in industrial cables and insulation polymers during service. This paper summarizes the results of aging assessments that were performed for cables installed in two U.S. nuclear power plants, one a pressurized water reactor and one a boiling water reactor. These cables had been in service for over 40 years and during plant operation were exposed to harsh environmental conditions including elevated temperatures and radiation.

For these assessments, a comprehensive series of measurements was performed to assess the aged condition of the cables. These cables came from different manufacturers, were manufactured in different years, and were constructed with a variety of jacket and insulation polymers including chloro-sulfonated polyethylene (CSPE), cross-linked polyethylene (XLPE)/cross-linked polyolefin (XLPO), neoprene, and ethylene propylene rubber (EPR). The goal of these assessments was to determine the current aged condition of the cable polymers and provide an estimate of how long the cable insulation materials could remain exposed to their in-service environmental conditions before reaching their end-of-life condition. Both nuclear power plants have received license renewals to extend their operation from 40 to 60 years, and the utilities need objective evidence to show that critical components such as cables will be able to function safely and reliably during the extended operating period.

The results of these assessments showed that the cables exhibited different aged conditions depending on the type of polymers they were constructed with and the environment they were exposed to during service. Some of the cables and insulation polymers showed signs of significant age-related degradation and were estimated to have approximately 5 years of remaining service life. Other cables exhibited no signs of significant age-related degradation and were estimated to have 50 years or more of remaining service life. Using the results of these cable aging assessments, plant personnel were able to (1) determine the overall aged condition of cables and insulation polymers using objective test results, (2) identify aged or degraded cables before they caused operability issues, and (3) avoid unnecessary and costly replacement of cables that can continue to operate safely and reliably.

摘要

多年来，电缆老化一直是国家和国际实验室、大学和私人组织进行的大量研究和开发 (R&D) 项目的主题。该研发旨在开发指导、设备和技术，以支持工业设施（如核电站、研究反应堆、废物设施和燃料制造厂）中在役电缆的老化管理。通过这些研究工作，已经开发出状态监测技术，可以确定在使用过程中工业电缆和绝缘聚合物中发生的老化相关退化的严重程度。本文总结了对安装在美国两座核电站中的电缆进行的老化评估结果，一个是压水反应堆，一个是沸水反应堆。这些电缆已经使用了 40 多年，并且在工厂运行期间暴露在包括高温和辐射在内的恶劣环境条件下。

对于这些评估，进行了一系列全面的测量以评估电缆的老化状况。这些电缆来自不同的制造商，生产年份不同，由各种护套和绝缘聚合物制成，包括氯磺化聚乙烯 (CSPE)、交联聚乙烯 (XLPE)/交联聚烯烃 (XLPO)、氯丁橡胶, 和乙丙橡胶 (EPR)。这些评估的目的是确定电缆聚合物的当前老化状态，并估计电缆绝缘材料在达到其使用寿命终止状态之前可以保持暴露在其使用环境条件下的时间。两座核电厂都获得了许可证更新，将其运行年限从 40 年延长至 60 年，

这些评估的结果表明，电缆表现出不同的老化条件，这取决于它们所用的聚合物类型以及它们在使用过程中所暴露的环境。一些电缆和绝缘聚合物显示出与老化相关的显着退化迹象，估计还有大约 5 年的剩余使用寿命。其他电缆没有表现出与老化相关的显着退化迹象，并且估计还有 50 年或更长时间的剩余使用寿命。使用这些电缆老化评估的结果，工厂人员能够 (1) 使用客观测试结果确定电缆和绝缘聚合物的整体老化状况，(2) 在老化或退化的电缆导致可操作性问题之前识别它们，