The degradation diagnosis of low voltage cables used at nuclear power plants

摘要

Low voltage cables which have been used for the supply of electric power and the propagation of control signals in nuclear power plants must he sound for safe and stable operation. The long use of nuclear power plants has been reviewed, and the degradation diagnosis to estimate the soundness of low voltage cables has been emphasized. Mitsubishi Cable Industries has established a degradation diagnosis method of cables which convert the velocity of ultrasonic wave in the surface layer of the cable insulation or jacket into breaking elongation, and has developed a degradation diagnosis equipment of low voltage cables used at nuclear power plants in cooperation with Mitsubishi Heavy Industries. This equipment can be moved by an ultrasonic probe by sequential control and measure the ultrasonic velocity automatically. It is capable of a fast and sensitive diagnosis of the cables. We report the outline of this degradation diagnosis equipment and an example of the adaptability estimation at an actual nuclear power plant.