Cable condition assessment for safe extension of nuclear power plants lifetime

Low-voltage cables at nuclear power plants (NPPs) are critical to plant function both during normal operating conditions and during accident response. Using electrical condition monitoring (CM) systems for cables will enhance safety in case of extension of plant lifetime.

Industrial Technologies

In situ CM of low-voltage cables is becoming increasingly important as existing power plants age. In addition, degradation mechanisms and profiles will be important in planning lifetime extensions to existing plants as well as in selecting cable materials and configurations for new plants. Although cables are an integral component of NPPs, the small number of European experts is spread throughout industry, utilities providers, research centres and universities. Scientists from many of these came together to study a representative set of cables in European NPPs and assess the performance of electrical CM techniques to characterize the ageing of cables in comparison with more conventional ones. EU funding of the project 'Ageing diagnostics and prognostics of low-voltage I&C cables' (ADVANCE)(opens in new window) facilitated this programme, including studies and tests. It also supported a rigorous programme of mobility, education and training of young scientists. Having selected six different cable types from an inventory of European NPPs, the team conducted two types of experiments. Short cables were aged and used to develop multi-stress models under various ageing conditions. Long cables were subjected to ageing tests tracked by various CM techniques. Data suggest that dielectric spectroscopy is the most promising of the electrical CM techniques investigated. Further, the team concluded that the reflectometry techniques are best suited at the moment to local defect evolution rather than global ageing. Further experiments were proposed to improve measurement techniques and analysis. In parallel, the team developed a new cable design to facilitate online CM of NPP cables. The ADVANCE project made an important contribution to the safety of existing and future NPPs through assessment of electrical CM techniques for low-voltage safety-related electrical cables. Criteria correlating physical, chemical and electrical properties to electrical condition will aid in predicting degradation and remaining service life. Extending the lifetime of NPPs is a priority of the global nuclear industry.