The Division 3
Emergency Diesel Generator (
EDG) was declared INOPERABLE following a trip during a routine monthly surveillance run. As soon as the Division 3
EDG was at full load it tripped off line (output breaker tripped). The Division 3
EDG supplies electrical power to the
High Pressure Core Spray System in the event of a loss of offsite power.
No problems occurred on the Division 3, 4160 volt, safety related bus.
This event is being reported in accordance with 10CFR50.72(b)(3)(v)(B), Event or Condition That Could Have Prevented Fulfillment of a Safety Function for a single-train system failure.
The NRC Resident inspector has been notified.
- * * THIS EVENT IS BEING RETRACTED ON 12/20/05 AT 1557 * * *
Subsequent trouble-shooting and testing determined that the cause of the engine trip on 11/21/05 was an invalid high coolant temperature trip signal. This trip is bypassed during a Loss of Coolant (LOCA) initiation of the system, therefore, it was determined that the EDG would have been able to perform its safety function during a LOCA. Following a Loss of Offsite Power (LOOP), reactor water level is expected to reach Reactor Pressure Vessel (RPV) Water Level Low Low (Level 2) within 30 seconds of the initiating signal. Once Level 2 is reached, both the EDG and the LOCA Trip bypass signals are actuated. It was determined that the bypass would have occurred prior to the high coolant temperature trip. Based on the above, it was determined that the Division 3 EDG would have been fully capable of performing its safety function under both LOCA and LOOP. The Division 3 EDG was restored to an operable condition at 0214 on 11/22/05.
The NRC Senior Resident Inspector has been notified.
Notified R3DO (H. Peterson).
