Vibration monitoring in Angra I nuclear power plant steam generator feedwater system

The safety and reliability are the primary criteria in the design and operation of a nuclear power plant. However, due to the aging of the plant and its components, it is difficult to assure that what was originally built and qualified under strict standards is still guaranteed. In order to assure safety, reliability, availability and capacity, aging management through predictive maintenance techniques are being introduced in most plants around the world. In this present work, the monitoring of the vibrations signatures at the Angra I nuclear power plant steam generators feedwater systems main components such as the main feedwater pumps, pressure breaker blocks and the by pass valves, is presented. The vibration data was acquired, afterwards some major repairs were performed and during the startup commissioning procedures. Some of the major repairs performed are: changing of one pump shaft with balancing and alignment, replacement of the original bypass control valves by new disk stack type pneumatic control valves. The results show that no major vibrations anomaly is present after the maintenance indicating adequacy of the repairs made. The monitoring of the vibration in nuclear power plant components is being increasingly used as a tool for predictive maintenance. (author)