“The Triple 5 System was THE FIRST Indication of a Leak”
Unit : B&W – 1300MW 3845psi
Location of Leak: Superheat Outlet Section
Facts: The unit is equipped with a 37 sensor AMS Leak Detection System and the plant has a Weekly Surveillance contract with Triple 5.
Timeline:
March 3: During the Weekly Surveillance check sensor 11 trends at 90dB – a 4dB increase during the past week.
March 17: The weekly surveillance check reveals an additional 6dB increase on sensor 11 reaching 96dB. Also noted on 3/10 was sensor 24 reaching 90dB – a 6dB increase.
March 19: The plant calls Triple 5’s 24 Hour Hotline for assistance in analyzing sensor 11, now trending at 101dB. The plant reports minimal water loss.
March 24: Triple 5 reports additional increases on sensors 11 and 24. Sensor 18 trends at 87dB – a 4dB increase.
March 30: Unit removed from service at noon as acoustic levels increase significantly.
Plant Follow Up: The initial leak was a tight crack in the middle of an original shop weld. Six other tubes were washed with leaks ranging from pinholes to 1/4” diameter holes. The leaks were located 10’ from the left side wall. Sensor 11 was first to respond. It is located 20’ below and 30’ in front of the leak.