INES-event
INES 0

Manual shutdown for repairing of main condenser tube

Ulchin unit 1 was operated at the rated power. On Aug. 11, 1996 conductivity and concentration of sodium ion were increased at #5 water-box of condenser. As the deterioration of S/G secondary side water chemistry was expected, condenser purification system was inserviced additionally and reactor power was decreased to 65%. Evaluation on the water chemistry of S/G secondary side was carried out and the results of it required the immediate shutdown. Ulchin unit 1 was manually shut down to hot shut down condition and maintained.
Justification: As full safety functions were available, the event is rated at level "0" as per user's manual Part III, Table II, A1.

Location: ULCHIN-1
Event date: Sun, 11-08-1996
Nuclear event report
Legenda & explanation