Vibration monitoring of the Atucha-I NPP reactor vessel: experience and future improvements Original Research Article

Keeping nuclear plant components in prime operating condition is essential for overall plant safety and availability. One way to assess the good operating condition of nuclear components is an on-line monitoring system. A vibration monitoring system is intended to monitor a component or system to ensure that changes in the mechanical integrity are detected early, even during operation. This paper describes the experience gained during the development of a vibration monitoring system for the Atucha-I Nuclear Power Plant reactor vessel that started up in 1990. High sensitivity velocity sensors were mounted on the closure head of the reactor vessel to monitor the vibrations. Some of the results obtained for different reactor operating conditions are presented in the form of frequency spectra or RMS values for different frequency bands. A description of the system, its evolution and future improvements are also included.