Semantic search
| 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 | |
| ENS 44456 | 1 September 2008 17:35:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Shutdown Due to Emergency Diesel Generator Shorting Ring Cracks | On September 1, 2008, at about 1035 PDT, Southern California Edison (SCE) began a planned shutdown of San Onofre Unit 3. This shutdown is in anticipation of exceeding the Allowed Outage Time (AOT) of 14 days of Technical Specification 3.8.1 Action B.4 for an inoperable Diesel Generator (Train B). The AOT is due to expire on September 2, 2008 at about 0200. If the system cannot be restored within the allowed outage time, a plant shutdown is required. The initiation of this shutdown is being reported in accordance with 10CFR50.72(b)(2)(i). An inspection of the DG generator revealed cracks in the shorting ring, requiring replacement of the generator. Post maintenance testing performed after replacement revealed anomalous readings. SCE determined that problem identification, repair and post test could not be performed before expiration of the AOT. Consequently, shutdown has been initiated. At the initiation of the shutdown, SONGS Unit 3 was operating at full power. SONGS Unit 2 is operating at approximately 99 percent power. The NRC Resident Inspectors have been briefed on the shutdown plans and will be provided with a copy of this report. | Emergency Diesel Generator | |
| ENS 44092 | 25 March 2008 15:40:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Plant Shutdown Initiated Due to Degraded Battery Voltage | On March 25, 2008 at approximately 0640 PDT, SCE discovered a battery with voltage slightly below Technical Specification limits. At approximately 0840 PDT, plant operators began cooling Moisture Separator Reheaters (MSR) in preparation for a Shutdown as required by TS 3.8.4. Initiating MSR cooldown reduced reactor power by 0.1%. Although plant operators had not initiated boration or control rod insertion, SCE is, nevertheless, reporting this occurrence in accordance with 10CFR50.72(b)(2)(i). At approximately 0850 PDT, the battery was restored to Operable status and MSR cooldown was suspended. At approximately 1112 PDT, the Unit was returned to full power. SCE is continuing to assess if additional actions are required. At the time the shutdown was initiated, Unit 2 was operating at about 100% power. Unit 3 continues to operate at about 100% power. The NRC Resident Inspectors have been briefed on the shutdown plans and will be provided with a copy of this report. Preliminary information indicates that the degraded voltage was due to loose terminal bolts. | Control Rod | |
| ENS 43579 | 19 August 2007 02:55:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | Emergency Diesel Generator Work Platforms Not Properly Restrained | On August 18, 2007, at about 1955 PDT, both of SONGS Unit 3 Emergency Diesel Generators (EDG) were found in a condition that was not seismically analyzed. At about 2015 PDT on August 18, 2007, both of SONGS Unit 2 EDGs were found to be in the same unanalyzed condition. The condition involved EDG maintenance work platforms that had not been properly restrained, and, in the position found, could potentially render the EDGs inoperable during a seismic event. SCE is reporting this occurrence as a potential loss of safety function in accordance with 10CFR50.72(b)(3)(v). SCE took immediate actions to properly restrain the EDG work platforms, and an evaluation will be conducted to determine the cause of this event. At the time of this occurrence, Unit 2 was operating at about 99% power and Unit 3 was operating at about 100% power. SCE has notified the NRC Senior Resident Inspector about this occurrence and will provide them with a copy of this report.
The licensee is retracting this report based on the following: On August 18, 2007, SCE reported that Emergency Diesel Generator (EDG) work platforms on both Units 2 and 3 had not been properly restrained. This resulted in a condition unanalyzed for seismic events. Consequently, both trains of EDGs on both Units 2 and 3 were declared inoperable. SCE evaluated configuration of the platforms for vulnerabilities to a design bases event. SCE concluded that the DGs were operable as-found. Consequently, SCE is retracting the phone report to the NRC (Event Log No. 43579)." The licensee will inform the NRC Resident Inspector. Notified R4DO (Jones). | Emergency Diesel Generator | |
| ENS 42451 | 29 March 2006 08:01:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Unit 3 Shutdown Due to Potential Safety Injection Tank Gasket Issue | On March 27, 2006, with Unit 2 in Mode 4 while starting up from a refueling outage, (Southern California Edison (SCE)) discovered that the gasket used to seal the manway cover for Safety Injection Tank (SIT) T-008 had become partially dislodged. The gasket is a 'flexitalic' type gasket which consists of a long section of crushable wire that is coiled and compressed between the manway cover and the safety injection tank flange. For SIT T-008, the flexitalic gasket had uncoiled and extended down into the SIT and prevented SIT outlet check valve MU040 from fully sealing in the closed position. On March 28, SCE inspected the remaining three SITs (SITs # 007, 009 and 010) and found the flexitalic gaskets degraded but intact and not interfering with other components. When this condition was discovered at Unit 2, San Onofre Unit 3 was operating at approximately 100 percent power. Similar flexitalic gaskets are also used for the manway covers on the four SITs at Unit 3. At 0001 PST on March 29, 2006, SCE conservatively declared both trains of the emergency core cooling system at Unit 3 inoperable. This placed Unit 3 in a TS 3.0.3 shutdown action statement. Plant Operators began the required Unit 3 shutdown at about 0050 on March 29, 2006. SCE is providing this phone notification to the NRC in accordance with 10 CFR 50.72(b)(2)(i) for the initiation of any nuclear plant shutdown required by the plant's Technical Specifications. The electric grid in the area is stable and Emergency Diesel Generators are available on Unit 3. There is no maintenance being performed on systems required for shutdown on Unit 3. The licensee notified the NRC Resident Inspector.
On March 29, 2006, SCE reported the initiation of the shutdown to the NRC Operations Center (Event Log No. 42451). At the time, SCE was concerned that if the gaskets were uncoiled they might have interfered with operation of the ECCS. After completing the plant shutdown, SCE inspected and found the gaskets degraded but not extending into the SIT and its discharge piping. In addition, subsequent evaluations by the SONGS NSSS vendor Combustion Engineering (now Westinghouse) determined the degraded gaskets (even if uncoiled and interfering with SIT outlet check valve from fully closing) would not have prevented the ECCS from performing its required safety function. Consequently, SCE was not required to declare Unit 3 ECCS inoperable and SCE is retracting the phone report to the NRC (Event Log No. 42451). SCE will submit a voluntary LER to document this condition. At the time of this report, Unit 2 and Unit 3 are in Mode 1 at approximately 100% power. The San Onofre Resident Inspector has been notified of this event and will be provided with a copy of this report. Notified the R4DO (Spitzberg). | Emergency Diesel Generator Emergency Core Cooling System | |
| ENS 41410 | 15 February 2005 05:55:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Tech Spec Required Shutdown | The following information was provided by the licensee via e-mail: On February 10, 2005, plant operators observed an abnormal flow condition on Unit 2 Train 'B' Component Cooling Water (CCW) from the Shutdown Cooling Heat (SDC) exchanger and, at about 2315 PST, declared Train 'B' of Containment Spray inoperable. This caused Unit 2 to enter a seven-day action statement (TS 3.6.6.1). Although it may have been possible to correct the abnormal flow condition on-line, SCE has elected to shutdown Unit 2. Plant Operators initiated the shutdown at about 2155 PST on February 14, 2005. SCE in reporting this occurrence in accordance with 10CFR50.72(b)(2)(i). At the time the shutdown was initiated, Unit 2 was operating at about 100% power. Unit 3 continues to operate at about 100 % power. The NRC Resident Inspectors have been briefed on the shutdown plans and will be provided with a copy of this report. | Shutdown Cooling Containment Spray | |
| ENS 40396 | 17 December 2003 11:15:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Technical Specification Required Shutdown Due to Loss of Both Trains of Safety Injection | The following information was obtained from the licensee via facsimile: 1. SYSTEMS AFFECTED: High Pressure Safety Injection (HPSI), Low Pressure Safety Injection (LPSI), Recirculation Actuation (System) (RAS), Containment Spray (CS). 2. ACTUATIONS AND THEIR INITIATING SIGNALS: None 3. CAUSES: 400 (volt) Motor Control Center (MCC) 3BE deenergized due to an overcurrent condition on the 'A' train 1E bus. 'B' train equipment is cleared for maintenance causing Technical Specification 3.0.3 entry. 4. EFFECT OF EVENT ON PLANT: Both trains of Safety Injection equipment inoperable with no flow capability requiring plant shutdown. 5. ACTIONS TAKEN OR PLANNED: Shutdown commenced at 0410 (PST). MCC 3BE is stripped and loads will be checked for faults while attempting to restore the bus. Train 'B' equipment will be restored as soon as possible. Continuation Sheet: Power/Mode will be reduced per T.S. 3.0.3 action until MCC 3BE loads restored or Tr(ain) 'B' equipment returned to service. (Plant required to be in) Mode 3 (within) 7 hrs, Mode 4 (within) 13 hrs. (and) Mode 5 (within) 37 hrs. No abnormal electrical lineups. No effect on Unit 2. LPSI pump/valves will need to be restored to allow Mode 5 entry. Plant personnel suspect a problem with the 1E bus feeder breaker. A new breaker will be installed after testing is completed. Bus loads are in the process of being checked for problems. At the time of the initial call, plant power was at 80% and decreasing at approximately 10% per hour. At 0939 PST, plant power was at 71% and decreasing. The 1E bus have been meggered with no problems found. Battery chargers are currently not operating due to loss of the buses but not expected to be a problem since DC loads are very low during mode 1 operations. The licensee has notified the NRC Resident Inspector. | Containment Spray |