05000244/LER-2012-001
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2442012001R00 - NRC Website | |
I.�DESCRIPTION OF EVENT
A. PRE-EVENT PLANT CONDITIONS:
- On June 03, 2012 the plant was in Mode 1 at approximately 100% reactor power. Reactor Coolant System (RCS) pressure was 2235 psig and RCS temperature was 574F. The offsite electrical system was in the 50%/50% lineup, meaning that each offsite circuit was providing power to two (2) of the four (4) 480 Volt Safeguards Busses.
B. EVENT:
- On June 03, 2012 at approximately 0239, offsite power circuit 767 was lost due to a fault caused by a raccoon. This resulted in a momentary loss of safeguards busses 16 and 17. The B emergency diesel generator automatically started and supplied power to busses 16 and 17 as designed.
- Off site power circuit 7T remained operable during this event. The offsite power configuration was later changed to a 100%/0% lineup, with circuit 7T supplying offsite power requirements.
- The plant remained at approximately 100% power throughout the event.
C. INOPERABLE STRUCTURES, COMPONENTS OR SYSTEMS THAT CONTRIBUTED TO THE
EVENT:
- None.
D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:
06/03/2012, 0239 EST Event Date and Time, Loss of Off-site power circuit 767 and B Emergency Diesel Generator automatic start supplying power to busses 16 and 17 06/03/2012, 0318 EST Busses 16 and 17 returned to off-site power (Circuit 7T) 06/03/2012, 0448 EST B Emergency Diesel Generator shut down 06/03/2012, 0607 EST Notification of B Emergency Diesel Generator start, event # 47988 under 10CFR50.72(b)(3)(iv)(A)
E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:
-None.
F. METHOD OF DISCOVERY:
- Main Control Board Alarms associated with loss of offsite power and Emergency Diesel Generator start.
G. MAJOR OPERATOR ACTION:
- Operations responded to the loss of circuit 767 using abnormal operating procedure AP-ELEC.1 "Loss of 12A and/or 12B Busses" - Offsite power was restored to bus 12 B using ER-ELEC.1 "Restoration of Off-site Power" - Restored offsite power to pre-event lineup with 0-6.9.2 H. � SAFETY SYSTEM RESPONSES:
- The B Emergency Diesel Generator operated properly and as expected.
II. � CAUSE OF EVENT:
- The cause is raccoon interaction with power lines causing a temporary fault (CR-2012-003664). The raccoon caused a line to ground fault. Pilot wire differential and overcurrent relays operated, opening primary and secondary side transformer breakers for circuit 767.
ANALYSIS OF THE EVENT:
- This event is reportable as an LER under 10CFR50.73(a)(2)(iv)(A) due to the automatic start of B Emergency Diesel Generator and loading onto its safeguards buses not being part of a pre- planned sequence during testing.
- There were no safety consequences as the redundant offsite circuit and Emergency Diesel Generators were operable and performed as designed.
IV � CORRECTIVE ACTIONS:
A. � ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS - Offsite power configuration was changed to 100%/0% lineup with Circuit 7T supplying power to all four (4) safeguards buses. B Emergency Diesel Generator was later stopped and aligned for auto standby - Control room personnel were contacted by RG&E stating that circuit 767 was available. They then returned offsite power to 50%/50% lineup power using procedure 0-6.9.2.
- Inspection of equipment revealed no damage B. � ACTION TAKEN TO PREVENT RECURRENCE - Development and installation of additional Animal Deterrent Devices is planned.
V � ADDITIONAL INFORMATION:
A. � FAILED COMPONENT(s) - None.
B. � PREVIOUS LERs ON SIMILAR EVENTS - A review of recent Ginna events involving the start of B Emergency, Diesel Generator revealed only one other event (LER 1997-002) that was caused by an animal, and all the events occurred external to Ginna and Station 13a:
- LER 2005-002 - LER 2005-003 - LER 2003-006 - LER 1997-002 MRC FORM 3E43* (164010)