05000424/LER-2014-004
| Vogtle Electric Generating Plant | |
| Event date: | 7-27-2014 |
|---|---|
| Report date: | 09-25-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4242014004R00 - NRC Website | |
A. REQUIREMENT FOR REPORT
This report is required per 10CFR 50.73(a)(2)(iv)(A) due to an unplanned manual actuation of the Reactor Protection System (RPS) and automatic actuation of the Auxiliary Feedwater System (AFW).
B. UNIT STATUS AT TIME OF EVENT
Model, 100 percent power
C. DESCRIPTION OF EVENT
While operating at 100 percent power, the Unit 1 Main Feed Pump A speed began to lower resulting in a loss of sufficient feedwater flow to maintain Steam Generator levels. The Operators in the Control Room observed the lowering feedwater flow and manually actuated the RPS, tripping the reactor prior to reaching any automatic RPS actuation setpoints. All rods fully inserted and the plant was stabilized in Mode 3. Decay heat was discharged to the condenser and no complications were experienced during the trip as all systems responded as designed.
The cause of the event was a loss in MFP A speed due to control oil leakage on the lockout solenoid valve.
D. CAUSE OF EVENT
The direct cause of the event was internal control oil leakage of the lockout solenoid valve which resulted in less than adequate control oil pressure. As a result, total feedwater flow to the Steam Generators lowered due to decreasing MFP A speed.
E. SAFETY ASSESSMENT
When the reactor tripped, all rods fully inserted and all safety systems actuated as designed. The unit was stabilized in Mode 3 at normal temperature and pressure and decay heat was discharged to the condenser. Because the plant responded as designed and there were no complications with plant shutdown, there was no adverse effect on plant safety or the health and safety of the public.
F. CORRECTIVE ACTION
The solenoid valve was replaced and post maintenance testing was performed satisfactorily.
G. ADDITIONAL INFORMATION
1. Failed Components:
Main Feed Pump A lockout solenoid valve.
2. Previous Similar Events:
INPO OE 21051 Recurring Solenoid and Relay Failures in Main Feedwater Pump Turbine Overspeed Test Circuit.
3. Energy Industry Identification System Code:
[JC] — Reactor Protection System [BA] — Auxiliary Feedwater [JB] — Feedwater/Steam Generator Water Level Control System