Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 52876 | 28 July 2017 19:06:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Alert Declared Due to Low Oxygen Levels Inside Containment | Containment atmosphere oxygen level was measured at 18.4 percent. This is below normal habitability level. The cause of the low oxygen level is a nitrogen leak inside containment Nitrogen has been isolated from containment and operators are preparing to purge containment. The licensee notified the State of California, local authorities and the NRC Resident Inspector. Notified the DHS SWO, FEMA OPS, USDA OPS, HHS OPS, DOE OPS, DHS NICC, EPA EOC. Notified FDA EOC, NuclearSSA, FEMA NWC and FEMA NRCC SASC via email.
The ALERT was terminated on 7/28/17 at 1819 PDT. The containment atmosphere was restored to normal conditions. The nitrogen source was isolated. The cause of the nitrogen leak into containment is under investigation. The licensee will notify the NRC Resident Inspector. The licensee has notified the State of California and the local authorities. The licensee plans to issue a press release. Notified the R4DO (Hay), NRR EO (Miller), IRD MOC (Grant). Notified the DHS SWO, FEMA OPS, USDA OPS, HHS OPS, DOE OPS, DHS NICC, EPA EOC. Notified FDA EOC, NuclearSSA, FEMA NWC and FEMA NRCC SASC via email. | ||
| ENS 51655 | 14 January 2016 22:43:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event - Security Condition That Does Not Involve Hostile Action | A security condition that does not involve a hostile action was reported by the Diablo Canyon security watch commander. At 1443 PST on 1/14/16, Diablo Canyon declared an Unusual Event, due to an unauthorized person in the Owner Controlled Area. Site Security was dispatched and assistance was requested from the local Sheriff's Department. The individual was apprehended. At 1602 PST on 1/14/16, Diablo Canyon terminated the Unusual Event after the individual was apprehended and placed in custody of local law enforcement. Diablo Canyon remained at 100 percent power for the duration of the event. No radiological release has occurred and all radiation levels are normal on both units. A press release is planned. The licensee has notified the NRC Resident Inspector and state and local authorities. Notified FEDS (DHS SWO, FEMA Ops, DHS NICC, and NuclearSSA via email.)
This Notification is being retracted. Upon further evaluation, Pacific Gas and Electric has determined that declaration of the Unusual Event was not required. The event did not constitute a threat or compromise to site security, did not involve a threat or risk to site personnel, did not represent a potential degradation to the level of safety of the plant, and did not affect the health and safety of the public. The licensee has notified the NRC Resident Inspector of the retraction. Notified R4DO (Whitten), IRD (Stapleton) and NRR (Morris). | ||
| ENS 48427 | 21 October 2012 07:09:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Seismic Event | HU1.1 Seismic event identified by earthquake felt in plant and US Geological Survey (USGS). An earthquake was felt onsite at approximately 0000 PDT. The licensee stated that two out of three methods for determining if an Unusual Event should be declared were met (i.e. the earthquake was felt in the plant and the earthquake was monitored by the USGS). The licensee characterized the earthquake as a "very mild" event. The licensee stated that, at the present time, there was no indication of damage to either unit and that both units remain at 100% power. The licensee is in the process of conducting walkdowns to confirm there was no damage to the plant. The USGS classified the magnitude of the earthquake as 5.3. The licensee notified state and local authorities and the NRC Resident Inspector. Notified other federal agencies (FEMA, DHS, DHS NICC and Nuclear SSA via email).
As of 1142 PDT on 10/21/12, the licensee terminated from the Unusual Event based on review of completed plant walkdowns. No damage was identified. Both Units are stable and in normal plant operations. The licensee notified state and local authorities and will notify the NRC Resident Inspector. Notified the R4DO (Pick), NRR EO (Bahadur), IRD MOC (Grant) and federal agencies (FEMA, DHS, DHS NICC and Nuclear SSA via email). | ||
| ENS 46668 | 11 March 2011 09:23:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notice of Unusual Event as a Result of a Tsunami Warning in the Area | The licensee declared a notice of unusual event as a result of a tsunami warning issued for the coastal areas of California. The tsunami warning is a result of a 8.9 magnitude earthquake off the coast of Japan. The licensee is in EAL HU1.5, 'Tsunami Affecting the Protected Area.' The NRC remains in the normal response mode. The NRC Resident Inspector has been notified.
A classification of unusual event was declared at 0123 PST on March 11, 2011 due to a tsunami warning issued by the NOAA for the California West Coast. Diablo Canyon Power Plant (DCPP) has implemented the requirements of Casualty Procedure M-5, 'Response to Tsunami Warning.' Plant personnel were evacuated from the DCPP intake structure at 0742 PST. Evacuation of personnel from the intake structure constitutes a deviation from DCPP license condition '2.E' and authorized pursuant to 10CFR50.54(x). No damage or injuries has been observed as a result of this tsunami event and there is no impact on the health and safety of the general public. Notified the R4DO (Farnholtz), R4RA (Collins), IRD (Marshall), and NRR (Grobe).
Diablo Canyon has terminated their Unusual Event at 1528 PST because the tsunami warning has been reduced to a tsunami advisory. No damage occurred during this event. Notified the R4DO (Farnholtz), IRD (Gott), NRR (Galloway), DHS (Gates), and FEMA (O'Connell) | ||
| ENS 46509 | 26 December 2010 00:25:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event Declared Due to High Winds | Notification of Unusual Event declared due to high winds. EAL HU 1.2 condition of peak wind in excess of 80 miles per hour have been met. Sustained winds at the present time are 53.5 miles per hour. Wind direction (from) 38.8 degrees. There has been no damage on-site. There are no plans to reduce reactor power on either unit at the present time. The Emergency Operations Center has not been activated. The storm front causing the high winds is expected to exit the area within the next three to four hours. The licensee notified the NRC Resident Inspector. The licensee notified the San Luis Obispo Sheriff and the State of California Office of Emergency Services.
Current wind speed is 3.7 miles per hour. Wind direction (from) 134.7 degrees. There has been no damage on-site. The access roads to the site are open and passable.
Current wind speed 9.2 miles per hour. Wind direction (from) 101.6 degrees. The NRC Senior Resident Inspector is on-site.
The licensee terminated the NOUE at 2021 PST. Winds are less than 2 mph gusting to 2.8 mph from 63.9 degrees. The storm has passed and no damage has been detected. The NRC Resident Inspector will be notified. Notified the R4DO (Werner), IRD (Gott), NRR EO (Howe), DHS (Knox), and FEMA (Fuller).
During a rain storm on December 25, 2010, PG&E declared an Unusual Event at the Diablo Canyon Power Plant due to indicated peak wind speed of 42.6 meters per second (m/s), (95.3 miles per hour (mph)), at the 10m elevation on the Primary Meteorological Tower, in excess of 80 mph indicated. After analyzing other wind speed instrumentation from the same time period, PG&E concluded that this reading did not accurately reflect meteorological conditions at that time. The next highest reading was taken at the 76m elevation on the Primary Meteorological Tower and indicated peak wind speeds of 23.7 m/s (53.0 mph). The Backup Meteorological Tower mechanical anemometers indicated a wind speed of 16.1 m/s (36.0 mph) for the 10m elevation, and 18.2 m/s (40.7 mph) for the 60m elevation. The Primary Meteorological Tower sonic sensors read both wind speed and wind direction with a single sensor. Concurrent with the Primary Meteorological Tower 10m wind speed spike, the 10m Primary Meteorological Tower wind-direction made a step-change from 153 degrees to 39 degrees. This step change indicated a value approximately 180 degrees opposite all other wind direction instrumentation indications. PG&E made the initial reporting of this event assuming the wind speed indicator at the 10m elevation on the Primary Meteorological Tower was functioning correctly. Analysis determined that this instrument was not functioning correctly. PG&E troubleshooting found the sonic wind speed and direction sensors are vulnerable to moisture intrusion. Moisture was found in the body of a wind speed and direction sensor after it had spiked in the rain. The vendor confirmed that moisture on the circuit board could cause an interruption of measurement, which would cause the sensor outputs to read high. PG&E identified moisture intrusion as the presumptive cause of the wind speed spiking . PG&E has sealed all sensors to eliminate the vulnerability. Given the above, PG&E retracts this event report. Notified the R4DO (Miller). | ||
| ENS 46036 | 23 June 2010 17:48:00 | 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 for a Cardox Discharge in the Turbine Building | A CARDOX release occurred in the Unit-1 main turbine lube oil room and an Unusual Event was declared. The release resulted in an atmosphere immediately dangerous to life and health resulting in an Alert notification. No injuries resulted, however, the crane bay in the center of the turbine building was evacuated. Approximately 30% of the CARDOX storage tank was discharged due to a malfunctioning solenoid valve. This valve had recently been replaced. The licensee notified the NRC Resident Inspector.
The licensee provided the following information as an update: On June 23, 2010, at 1035 PDT, an accidental discharge of CARDOX into Unit 1 Main Lube Oil Reservoir Room occurred during testing. On June 23, at 1048 PDT, an Unusual Event was declared for DCPP Unit 1. On June 23, at 1056 PDT, an Alert was declared for DCPP Unit 1. The DCPP Unit 1 reactor remains at full power. No safety related equipment has been impacted. There were no injuries to personnel and no equipment damage. Offsite assistance was requested to assist in event response. Pacific Gas and Electric Company issued the first press release at 1225 PDT on June 23, 2010. Further press releases will be issued as necessary until the event is terminated. The licensee notified the NRC Resident Inspector." The licensee also informed state and local agencies. Notified R4DO (Pick).
The licensee has terminated the Alert at 1715 PDT based on restoring accessibility to all plant area. The licensee will inform state/local agencies, the NRC Resident Inspector and issue a follow-up press release. Notified R4DO (Pick), NRR EO (Cunningham), IRD (Morris), DHS (Inzer), FEMA (Hollis), DOE (Yates), USDA (Petrick), and HHS (Lee). | Main Turbine | |
| ENS 45992 | 9 June 2010 18:12:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Toxic Gas/Chemical Spill in the Protected Area | Toxic gas in the Owner Controlled Area that adversely affects normal operations. The licensee declared an Unusual Event under EAL HU3.1 at 1112 PDT. During sodium hydroxide (NaOH) transfer operations on site, a drain valve leak occurred in the condensate polisher buttress area. Onsite personnel responded and stopped the leak. There were no injuries to personnel, no equipment damage and no offsite assistance required. The licensee has notified the NRC Resident Inspector.
Responder access to area has been restored. Approximately 5 gallons of NaOH have been contained. NOUE exit criteria will be that normal access to the polisher buttress is restored. The licensee has notified the NRC Resident Inspector. Notified IRD (Gott), NRR EO (Thorp) and R4DO (Powers).
The licensee has terminated from the Unusual Event at 1241 PDT. Normal access to all plant areas has been restored. Notified IRD (Gott), NRR EO (Thorp), R4DO (Powers), DHS (Kettles) and FEMA (O'Connel). | ||
| ENS 45112 | 2 June 2009 08:22:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event - Smoke Alarm in Protected Area Lasting Greater than 15 Minutes | Licensee declared an Unusual Event due to a possible fire in the protected area inside containment. The smoke alarm could not be verified before 15 minutes, therefore licensee entered into EAL HU 2.1. Seventeen smoke detectors located inside the containment feed into this alarm, and it is unknown if more than one smoke detector initiated the alarm. The local fire department was not requested to respond to the site. Licensee is sending personnel inside containment to investigate whether or not this alarm was spurious. There is no indication of smoke or an increase in temperature in or around the containment. There was no radiological release to the environment.
Licensee completed their investigation inside containment and determined there was no fire. Licensee terminated the Unusual Event at 0618 EDT. Licensee has notified the NRC Resident Inspector. Notified R4DO (Ryan Lantz), IRD MOC (Jeff Grant), NRREO (M. Evans), DHS (Inzer), FEMA (D. Barden) | ||
| ENS 44419 | 17 August 2008 07:12:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unusual Event Declared Due to Fire in Main Bank Tranformer | At 0012 the licensee declared a Notice of Unusual Event due to a fire in Main Bank Transformer. The licensee is fighting the fire along with offsite assistance from CAL FIRE. The unit is shutdown and stable in mode 3. All control rods fully inserted on the trip. Decay heat is being removed via auxiliary feedwater to the steam generators steaming to the main condenser via the main condenser steam dumps. Emergency buses remain powered via offsite power with emergency diesel generators available if required. The licensee will notify the NRC Resident Inspector. Notified DHS (Barnes), FEMA (Blankenship). * * * UPDATE FROM J. DILLIS TO J. KOZAL AT 0501 EDT ON 8/17/08 * * * The fire is out. Plant personnel are assessing the damage in the main transformer area. The plant is stable in mode 3. The licensee will notify the NRC Resident Inspector. * * * UPDATE FROM J. DILLIS TO P. SNYDER AT 0542 EDT ON 8/17/08 * * * The licensee has terminated the Notice of Unusual Event at 0231 PDT due to the fact that the fire was out and no reflash occurred. The plant remains stable in mode 3. The licensee will notify the NRC Resident Inspector. Notified R4DO (Lantz), IRD (McMurtray), NRR EO (Wermiel), R4 (Collins), NRR (Grobe), DHS (Wallace), FEMA (Biscoe).
This is an update of the Notification of Unusual Event due to Fire in the 'C' phase of the main bank transformer, and Automatic Reactor Trip. This update is to report automatic actuation of the auxiliary feedwater system (AFW) and is being reported as an 8-hour non-emergency event in accordance with 10 CFR 50.72(b)(3)(iv)(A) 'System Actuation.' The unit is stable in mode 3 (Hot Standby) with offsite power being supplied to all buses via the 230 Kv startup circuit. All rods fully inserted on the reactor trip. All systems performed as designed. Operators are preparing to place the unit in Mode 5, while preparing to assess the damage to the 500 Kv transformer. All emergency diesel generators remain operable in standby. Unit 1 was unaffected by this event and remains at 100% power. This notification also constitutes a late 4 hour notification for the RPS actuation. To summarize, on August 16, 2008, at 2356 PDT, the 'C' phase 500 Kv transformer failed resulting in a fire and an automatic reactor trip, and automatic actuation of AFW. An unusual event was declared on August 17, 2008, at 0012 PDT due to the fire. Cal Fire was called to assist and support the on-site fire brigade. The fire was extinguished and the NUE was downgraded at 0231 PDT. The NRC Resident Inspector has been notified as well as State and local government agencies. The licensee intends to issue a press release. R4DO (Lantz) notified. | Steam Generator Emergency Diesel Generator Auxiliary Feedwater Main Transformer Main Condenser Control Rod | 05000323/LER-2008-001 |
| ENS 44357 | 21 July 2008 16:08:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared - Unable to Validate a Fire Alarm within 15 Minutes | The licensee received a fire alarm (smoke alarm) for the Auxiliary Building Ventilation Room at 0853 PDT. An operator was dispatched to visually inspect the area of the fire alarm. The area was not able to be accessed due to a high delta pressure across the door. Operators were not able to access the area within 15 minutes of receiving the alarm and declared EAL HU 2.1 at 0908 PDT. A maintenance worker in the area of the alarm opened the door from the other side and an operator was able to visually inspect the area. The area was free of smoke and fire and the Unusual Event was exited at 0915 PDT. The licensee performed required notifications to the State of California and the local government. The NRC Resident Inspector was notified.
The licensee plans to issue a press release concerning the Unusual Event. The NRC Resident Inspector will be notified. R4DO (Deese) informed. | ||
| ENS 43047 | 12 December 2006 21:22:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Circulating Water Pump Failure Causes Explosion in Intake Structure | On December 12, 2006, at 1322 PST, while conducting power ascension operations with Unit 2 at approximately 25 percent power, an electrical failure occurred in the Unit 2 circulating water pump motor enclosure (CWP) 2-1. A loud bang and explosion was reported to the Unit 2 control room. At 1322 PST, an electrical transient was experienced on Unit 2 12-Kv non-vital bus 'D' which in turn caused reactor coolant pump (RCP) 2-2 and RCP 2-4 motor breakers to trip on 12kV non-vital bus 'D' undervoltage, initiating an automatic reactor trip. The reactor trip signal was initiated when 2 out of 4 RCP motor breakers opened. All control rods fully inserted in response to the reactor trip and all plant systems functioned as required. The auxiliary feedwater system for Unit 2 was manually actuated per plant procedures, before an auto-start signal for this system was generated. At 1356 PST, DCPP Fire Department first responders reported that the fire was out. At 1340 the licensee declared a Notice of Unusual Event (NUE), number 23, 'Confirmed Explosion Onsite'. Decay heat is being removed via auxiliary feedwater to the steam generators steaming to the atmospheric dump valves. Emergency power is being supplied via offsite power. The NRC resident inspector has been informed and was onsite at the time of the Unit 2 reactor trip. Diablo Canyon Power Plant (DCPP) Unit 2 is presently in Mode 3. There were no injuries associated with this event. Investigations into the electrical transient are ongoing. DCPP Unit 2 will remain in Mode 3 pending the results of this investigation. An estimated restart of DCPP Unit 2 is not known at this time. DCPP Unit 1 is unaffected and remains in Mode 1 at 100% power. * * * UPDATE AT 1730 EST ON 12/12/06 FROM T. CHITWOOD TO P. SNYDER * * * The licensee terminated the Unusual Event at 1430 PST. The Notice of Unusual Event was terminated due to the fact the licensee assessed the damage to the circulating water pump and determined that the explosion was caused by a breaker in the local area. The licensee fire brigade was satisfied that the fire was extinguished and that the damage was confined to the local area of circulating water pump 2-1. The licensee notified the NRC Resident Inspector. Notified the R4DO (Smith), NRR EO (Highland), IRD (Wilson), DHS (Inzer), and FEMA (Discoe). * * * UPDATE AT 1841 EST ON 12/12/06 FROM T. CHITWOOD TO J. ROTTON * * * The licensee provided an update to make the formal 4 hour notification pursuant to 10 CFR 50.72 (b)(2)(iv)(B) due to the RPS actuation while critical, and the formal 8 hour notification pursuant to 10 CFR 50.72 (b)(3)(iv)(A) due to the actuation of the auxiliary feedwater system. The licensee notified the NRC Resident Inspector. Notified the R4DO (Smith), and NRR EO (Highland). | Steam Generator Auxiliary Feedwater Control Rod | 05000323/LER-2006-004 |
| ENS 41774 | 15 June 2005 03:50:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event Due to Tsunami Warning | Diablo Canyon Units 1 and 2 declared a Notification of Unusual Event at 2050 PDT 06/14/05 due to the receipt of a Tsunami Warning from the California State Warning Center. The licensee notified State and local agencies and will notify the NRC Resident Inspector. The NRC remained in the Normal Mode.
The Tsunami Warning was cancelled and Diablo Canyon Units 1 and 2 terminated the Notification of Unusual Event at 2138 PDT 06/14/05. The licensee notified State and local agencies and the NRC Resident Inspector. | ||
| ENS 41076 | 28 September 2004 17:30:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Seismic Activity | Earthquake felt at plant site (at 1015 PDT) registering 0.012 g. No damage on plant site noted. Release to the environment remains within normal operating levels, and effluent radiation monitors did not alarm. No protective action required. The Licensee notified the NRC Resident Inspector.
Plant walk down in progress. No damage noted." The Licensee notified the NRC Resident Inspector.
Information Call: No plant damage detected by walk downs or equipment testing. R4DO (Linda Howell) notified. The Licensee will notify the NRC Resident Inspector.
Information Call: No plant damage detected by walk downs or equipment testing. The licensee notified the NRC Resident Inspector. R4DO(Howell) will be notified.
The licensee terminated the NOUE at 1215 PDT. "No plant damage has been detected by plant walkdowns or equipment testing." NRC exited Monitoring at 1600 EDT Notified R4DO (L Howell), NRR (Skeen, Borchardt), IRD (Frant, Wilson), Chairman Office (Holahan), EDO (Mitchell), PAO, Dir of Comm. (Outlaw), DHS (Morison), FEMA (Caldwell), USDA (Thomas), DOE (Wyatt), NRC DOT (Crews), and HHS (R. Harlan) | ||
| ENS 40408 | 22 December 2003 19:22:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event - Earthquake | At 1116 PST on 12/22/03, an earthquake was felt on-site measuring 0.04g on plant seismic instrumentation. The licensee declared an Unusual Event at 1122 PST per EAL 18 (greater than 0.01g) . Both Units 1 and 2 continue to operate at 100% power. The local electrical grid is stable and all Emergency Diesel Generators are fully operable. A number of plant tank level were momentarily alarmed. The Unit 2 Main Turbine Electro-Hydraulic Control (EHC) pump tripped and was successfully restarted. Plant walk-down inspections are in progress. The licensee notified the NRC Resident Inspector. The National Earthquake Information center reports that the earthquake measured 6.5 R and was centered approximately 5 miles Northeast of San Simeon, CA or approximately 35 miles Northwest of the Diablo Canyon site.
The licensee terminated the NOUE at 1212 PST following a 24 hour period after the earthquake. It was determined that the probability of an earthquake at this point is no greater than it was prior to the earthquake that occurred on 12/22/03. The licensee notified the NRC Resident Inspector. Notified R4DO (Smith), NRR EO (Reis), DIRO Manager (Nieh), FEMA (Eaches) and DHS (Bozzo). | Emergency Diesel Generator Main Turbine | |
| ENS 40258 | 18 October 2003 07:52:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Earthquake Felt on Site. Entered Emergency Action Level (Eal) 18 | Earthquake felt on plant site measured at 0.02g. Both Units remain at 100% State and Local County notified by the licensee. Unusual Event declared per EAL 18, (greater than 0.01g) . Two jolts several minutes apart were felt in the Control Room. The electrical grid is stable, all Emergency Core Cooling Systems and all Emergency Diesel Generators are fully operable if needed. Licensee will perform walkdowns of the plant to check for any damage. Turbine supervisor system indicated high main turbine bearing vibration on both main turbines (cleared right away) and one of the Unit 1 Accumulator levels alarmed (also cleared right away). Following information from Earthquake Center located in Colorado: Two earthquakes both magnitude 3.4, located 10 miles Southwest of San Luis Obispo. First earthquake occurred at 0027 PDT and the other earthquake occurred at 0039 PDT. The NRC Resident Inspector will be notified.
EAL 18 exited and Unusual Event Classification terminated at 0330 PDT. Walkdown of plant completed with no damage to plant observed. R4D0 (G. Sanborn), HQPAO (Gagner), FEMA (Austin), DHS (V. Cates), DIRO (S. Frant), & (G. Holahan) notified. NRC Resident Inspector informed by licensee. | Emergency Diesel Generator Main Turbine Emergency Core Cooling System |