Feedpump discharge line vibration solved at Byron Station, Unit 2

Ever since its 1987 start-up, the discharge piping on the motor-driven, steam generator feedwater pump at the Byron Station, Unit 2, has experienced severe vibration problems. This problem has also arisen at the three other duplicate nuclear plants on the Commonwealth Edison system. A study was instituted at the Byron Station, Unit 2, to determine the causes of this vibration. After a thorough review of several potential causes for the problem, it was determined that abrupt flow changes in the discharge piping were the cause. Therefore these abrupt flow changes were eliminated and a larger regulating valve was installed. This dramatically reduced vibration to an acceptable level. Based on this experience, similar modifications are either completed or underway at the Byron Station, Unit 1 and the Braidwood Station, Units 1 and 2