05000255/LER-2008-003
| Palisades Nuclear Plant | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2552008003R00 - NRC Website | |
On May 23, 2008, at 1249 hours0.0145 days <br />0.347 hours <br />0.00207 weeks <br />4.752445e-4 months <br />, with the plant in Mode 1 at 100% power, an actuation of the 346 negative sequence generator relay [87;EL] caused an actuation of the 386C coastdown lockout relay [86;EL]. The 386C relay actuation caused the main generator output breakers [BKR;FK] in the switchyard to open, causing a turbine [TRB;EL] trip, which actuated the reactor protective system [JC] to trip the reactor [RCT;AB]. As expected, the auxiliary feedwater system [BA] started automatically to recover steam generator [SG;AB] level.
There were no inoperable structures, systems, or components at the start of this event that contributed to the event. The normal heat sink (main condenser) remained available.
The event is reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in an actuation of both the reactor protection system and the auxiliary feedwater system.
CAUSE OF THE EVENT
The cause of the generator negative sequence relay actuation could not immediately be determined. The relay spuriously failed.
CORRECTIVE ACTIONS
The relay was replaced and sent to ABB for analysis. The problem could not be reproduced at ABB.
The relay 346 current transformer circuitry and associated wiring will be inspected for degradation during a future outage.
SAFETY SIGNIFICANCE
The event is considered to be of very low safety significance. All safety systems functioned as expected.
PREVIOUS SIMILAR EVENTS
None