 INES 0 |
TURBINE AND REACTOR TRIP DUE TOMFCV TROUBLE |
Yonggwang unit 1 was under full power operation. At 11:22 December 3, 1994 Main Feedwater Control Valve (MFCV) "A" was opeened due to trouble of MFCV positioner which resulted in level increase of Steam Generator #1.
Turbine trip occurred due to "S/G Hi-Hi level" signal and reactor trip followed. Investigation revealed MCFV positioner malfunction therefore positioner was replaced with new one and tested. Yonggwang-1 was returned to reactor criticality at 17.50, December 3, 1994. There was no release of radioactive material outside the reactor building and no unplanned exposure to employees.
Even though there had been two trips caused by the same cause, the Evaluation Committee of Severity on Incident and Failure of Nuclear Power Plants investigated the action taken by personnel and concluded that prevention of reoccurrence of this event had been attempted. The Committee determined therefore level 0 for this event.
Justification: As full safety functions were available the event is rated at level 0 as per users manual Part III, Table II, A1.
Event date: Sat, 03-12-1994
