U.S. Nuclear Regulatory Commission
Event Reports For
10/24/2013 - 10/25/2013
** EVENT NUMBERS **
|Power Reactor ||Event Number: 49471 |
| Facility: OCONEE |
Region: 2 State: SC
Unit: [ ] [ ] 
RX Type:  B&W-L-LP, B&W-L-LP, B&W-L-LP
NRC Notified By: MIKE TATE
HQ OPS Officer: BILL HUFFMAN
| Notification Date: 10/24/2013 |
Notification Time: 09:45 [ET]
Event Date: 10/24/2013
Event Time: 05:53 [EDT]
Last Update Date: 10/24/2013
| Emergency Class: NON EMERGENCY |
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
| Person (Organization): |
STEVEN VIAS (R2DO)
|Unit ||SCRAM Code ||RX CRIT ||Initial PWR ||Initial RX Mode ||Current PWR ||Current RX Mode |
|3 ||M/R ||Y ||100 ||Power Operation ||0 ||Hot Standby |
|MANUAL REACTOR TRIP FROM FULL POWER DUE TO FEEDWATER SYSTEM OSCILLATIONS |
"At 0553 EDT on 10/24/2013, Oconee Unit 3 was manually tripped due to oscillations in the feedwater system in anticipation of an automatic reactor trip. At 0549 EDT, Unit 3 began experiencing small feedwater oscillations. The feedwater control system was placed in manual in an attempt to stabilize feedwater flows. Feedwater oscillations continued to grow in magnitude and at 0553 EDT, a manual trip was directed to prevent an automatic reactor trip.
"Due to an RPS actuation, this event is being reported as a 4 and 8 hour Non-Emergency per 10 CFR 50.72 (b)(2)(iv)(B) and 10 CFR 50.72 (b)(3)
"Following the reactor trip, four main steam relief valves failed to reseat. Procedure guidance was utilized to reduce main steam system pressure by approximately 30 psig to reseat the main steam relief valves. All main stream relief valves are now reseated. All other post trip conditions were normal and all other systems performed as expected. Unit 3 is currently in Mode 3 and stable.
"Operations have been stabilized on Unit 3. A post-trip investigation is in progress, per site procedures and directives."
The licensee has notified the NRC Resident Inspector.