INES-event
INES 0

Reactor trip due to improper operation of main feedwater bypass valve

This unit experienced steam generator "A" level fluctuation during re-startup in reactor power of 16%. Operator changed the operation mode of feedwater level control from automatic to manual control. However, steam generator level was not stabilized. Reactor was tripped by steam generator level low-low signal. Investigation revealed that extension rod and hand jack guide plate of main feedwater bypass valve were damaged and bent because their position was not adjusted.
There was no release of radioactive materials outside the reactor building and no unplanned exposure to employees.
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: KORI 1
Event date: Sun, 31-03-1996
Nuclear event report
Legenda & explanation