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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 49975 | 29 March 2014 04:10:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Discovery of After-The-Fact Emergency Condition -- Unusual Event Due to Seismic Event | On March 28, 2014 at 2110 PDT, station staff felt a minor seismic event, which was verified on the NEIC (National Earthquake Information Center). On-shift staff reviewed basis documentation and EAL (Emergency Action Levels) classification, and concluded the event was below the threshold to classify the event. During post event reviews (conducted on 3/31/2014), it has been determined that those events met the classification criteria for declaration of a Notification of Unusual Event for a seismic event as specified by the Emergency Plan. No emergency situation exists at this time. Site personnel did perform the steps of the Earthquake abnormal operating procedure even though the entry requirements were not met. There were no plant or equipment issues identified during the site walk downs. The licensee has notified the NRC Resident Inspector, the State of California and other Local authorities. | ||
| ENS 48232 | 26 August 2012 19:39:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Earthquake Felt Onsite | A Notice of Unusual Event (NOUE) was declared at San Onofre due to an earthquake felt on site (EAL HU1.1). The US Geological Survey indicates that there was a 5.3 magnitude earthquake near Brawley California, about 125 miles southeast of the plant. There were no indication of any impact to site operations other than being felt by personnel. Equipment inspections and walkdowns are in progress. The licensee has notified state and local authorities. The NRC Resident Inspector will be notified. Notified other FEDS (FEMA, DHS, DHS NICC and Nuclear SSA via email).
On August 26, 2012 at 1346 PDT, San Onofre exited the Unusual Event based on an earthquake felt on site. Shortly after exiting the UE, the licensee felt more shaking in the control room. The licensee confirmed with the US Geological Survey that there has been an aftershock. The aftershock was approximately the same magnitude (5.4) and location as the original earthquake (about 125 southeast of the site). The licensee declared another unusual event at 1403 PDT. The licensee will re-perform all equipment walkdowns and inspections. The NRC Resident Inspector has been notified and is reporting to the site. R4DO (Hay), NRR EO (Lubinski), and IRD (Gott) notified.
Exited the NOUE HU1.1 - Earthquake at 2017 PDT on 8/26/12. The licensee will notify the NRC Resident Inspector. Notified the R4DO (Hay), NRR (Lubinski), IRD (Gott), DHS, FEMA, and DHS NICC. | ||
| ENS 47856 | 20 April 2012 19:49:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Electrical Panel Fire in Turbine Building | San Onofre Unit 2 declared an Unusual Event at 1249 PDT today due to an electrical fire within a fire detection panel (2L319) in the Unit 2 turbine building. The fire was declared extinguished at 1314 PDT after the panel was de-energized. The location of the fire had no impact on plant operation, equipment, or personnel safety. No offsite assistance was necessary. The licensee exited the Unusual Event at 1341 PDT after the licensee confirmed that the fire was terminated and there was no ongoing risk to the plant. The licensee notified state and local authorities and the NRC Resident Inspector. The NRC Operations Center notified other Federal Agencies (DHS SWO, FEMA Ops, DHS NICC, and NuclearSSA via e-mail). | ||
| ENS 47401 | 1 November 2011 21:50:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Alert Declared Due to an Ammonia Leak | On November 1, 2011 at 1450 PDT, San Onofre Unit 3 declared an ALERT and entered EAL HA3.1 due to an ammonia leak that prevented access to local areas. The plant is in a stable condition while the leakage is being secured. The turbine building on Unit 3 has been evacuated. Plant personnel are in the process of verifying no presence of ammonia in the turbine building. There was no impact on Unit 2.
At 1807 PDT licensee exited the ALERT and EAL HA3.1. The leak was at the Ammonia day tank and was flowing through an overflow vent into the berm. The high level in the Ammonia day tank was due to a leaking closed valve between the Demineralizer system and the ammonia bulk storage. The berm area was drained of all fluids. The wind direction caused the ammonia fumes to travel to the Unit 3 turbine deck. No off-site HAZMAT personnel came on-site. At 1756 PDT the precautionary evacuation of on-site personnel was terminated. Unit 2 was not affected from this event. The NRC Resident Inspector was notified. Notified NRR EO (Fredrick Brown), R4DO (Vincent Gaddy, IRDMOC (Jeff Grant), DHS (Hill), DOE (Doyle), USDA (Krauf), FEMA (Fuller) and HHS (Fajardo).
On November 1, 2011, Southern California Edison notified the California Emergency Management Agency at 1755 PDT and the San Diego Department of Environmental Health at 1810 PDT that approximately 25 gallons of Ammonium Hydroxide was spilled under the Ammonium Hydroxide day tank located outside the Unit 3 turbine building. The spill was contained in a berm under the tank and subsequently cleaned up. Both Units 2 and 3 were at approximately 100% power at the time of the event. Notified the R4DO (Gaddy). | ||
| ENS 47064 | 16 July 2011 13:12:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Entry Into Eal Hu4.1 | The licensee declared an Unusual Event at 0612 PDT due to entry into EAL HU4.1 for a security-related event. Contact the Headquarters Operations Officer for details. The licensee notified State and local authorities and the NRC Resident Inspector.
The licensee exited the Unusual Event at 0950 PDT after verifying that the exit criteria for EAL HU4.1 had been met. Contact the Headquarters Operations Officer for details. The licensee notified State and local authorities and the NRC Resident Inspector. Notified NRR EO (Giitter), R4DO (Cain), IRD MOC (Morris), ILTAB (Allston), DHS SWO (Gates), and FEMA (Via).
After further investigation, the licensee determined that the declaration of the Unusual Event had been a conservative action not required by site procedures. Contact the Headquarters Operations Officer for details. The licensee notified the NRC Resident Inspector. Notified R4DO (Hagar), NRR EO (Thorp), and IRD MOC (Gott). | ||
| ENS 45810 | 4 April 2010 22:42:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event - Earthquake Felt on Site | Seismic Recording System activation with ground motion readily felt by control room personnel. Plant inspections performed to date show no observable damage to systems or structures." The seismic event was reported by U.S. Geological Survey as a magnitude 7.2 event occurring 26 km (16 miles) SW of Guadalupe Victoria, Baja California, Mexico. Initial ground motion analysis on site indicated 0.027 g acceleration in the transverse direction. The licensee has notified the NRC Resident Inspector.
The Notification of Unusual Event classification was terminated at 1725 PDT on 4/4/2010 after completion of walk downs with no equipment issues being found. Notified R4DO (Okeefe), NRR EO (Bahadur), IRD (Gott), DHS (Vestal), and FEMA (Via). | ||
| ENS 45564 | 12 December 2009 09:26:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Unusual Event Declared Due to Both Emergency Diesel Generators Being Inoperable | A declaration of Unusual Event per EAL D.1-1 was made at 0126 PST on 12/12/09 due to both EDGs being inoperable. This condition places the Unit in a required Technical Specification Shutdown condition and the Unit is proceeding to shutdown. Train "B" EDG was declared inoperable at 0025 PST on 12/11/09 due to annunciator issues associated with the EDG. The cause of the annunciator issues has still not been identified. This placed the licensee into the Action Statement for LCO 3.8.1 that required verification of operability of the Train "A" EDG within 24 hours. During the operability test of the Train "A" EDG, the diesel failed to reach voltage and frequency (the EDG tripped on startup) and it was also declared inoperable. As a result, the licensee entered Action F of LCO 3.8.1 and is required to be in Mode 3 within 6 hours and Mode 5 within 36 hours. The licensee declared the UE at 0126 and commenced power reduction. Mode 3 must be reached by 0625 PST on 12/12/09 and Mode 5 must be reached by 1225 on 12/13/09. Besides the EDGs, all other safety related systems are operable. The licensee has notified State and local authorities and the NRC Resident Inspector.
On December 12, 2009, at about 0025 PST, SONGS Unit 3 Emergency Diesel Generator (EDG) 3G002 was determined to be inoperable. EDG 3G003 had been declared inoperable prior to this, resulting in both Unit 3 EDGs being inoperable. At about 0025 on December 11, 2009, EDG 3G003 (Train 'B') was declared inoperable as a result of work being done on an annunciator power supply. SONGS Technical Specifications (TS), section 3.8.1.B, requires that the associated EDG, 3G002 (Train 'A') be tested within 24 hours to ensure that the EDG was also not inoperable due to a common cause. On December 12, 2009, at about 0025, EDG 3G002 was declared inoperable when it did not achieve required voltage and frequency during an attempted start. SCE is reporting this occurrence as a loss of safety function in accordance with 10 CFR 50.72(b)(3)(v). The loss of both EDGs on Unit 3, per TS 3.8.1.E, requires restoration of one EDG within 2 hours. This action was not met, and as a result TS 3.8.1.F required the unit to be shutdown to Mode 3 within 6 hours. This shutdown action began at 0126 PST. Also, pursuant to the SONGS Emergency Plan, the shutdown of Unit 3 under TS 3.8.1.F required declaration of an Unusual Event. Both the TS required shutdown action and the declaration of the Unusual Event were reported to the NRC pursuant to 10CFR50.72 in an earlier notification (same NRC Operations Log #45564). SCE is taking actions to restore one of the EDGs to operability. At the time of this occurrence, Unit 2 was in a Steam Generator Replacement Outage, and Unit 3 was at approximately 100% power proceeding to a Mode 3 shutdown. The NRC Resident Inspector has been notified of this occurrence and will be provided with a copy of this report. Notified R4DO (Spitzberg).
The licensee exited their Unusual Event (and TS required shutdown) at 0645 PST based on restoration of operability of the "B" Train EDG. The "B" Train EDG annunciator issue was repaired and the EDG started and load tested per Technical Specification requirements. The EDG was declared operable at 0511 PST. The licensee is currently holding at 40% and planning to return to full power. Investigation into the starting problem of the "A" Train EDG is still ongoing. The licensee has notified the NRC Resident Inspector, State and local authorities. R4DO(Spitzberg), NRR(McGinty), and IRD MOC (Grant) notified. Also notified DHS (Inzer) and FEMA (Via). | Steam Generator Emergency Diesel Generator |