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Start date | Reporting criterion | Title | Event description | System | LER | |
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ENS 57066 | 4 April 2024 23:18:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event Due to Fire Alarm in the Vital Area | The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: On 4/4/2024 at 1618 MST, a Notification of Unusual Event, HU4.2 was declared based on an unverified fire alarm in the containment building greater than 15 minutes. Palo Verde, Unit 3 was operating in Mode 1 at 91 percent power due to end of cycle coast down to a refueling outage. There is no known plant damage at this time. Offsite assistance cannot enter the containment building, therefore, offsite assistance was not requested. The plant is stable in Mode 1. The licensee notified State and local authorities and the NRC Senior Resident Inspector. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), CWMD Watch Desk (email), DHS NRCC THD Desk (email), and DHS Nuclear SSA (email).
The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At 2013 MST, Palo Verde Unit 3 terminated the notification of unusual event. The basis for termination was that a containment entry was performed. All levels were inspected, and no fires were found. The NRC Resident Inspector has been notified. Notified R4DO (Deese), IR-MOC (Crouch), NRR-EO (Felts), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), CWMD Watch Desk (email), DHS NRCC THD Desk (email), and DHS Nuclear SSA (email). | ||
ENS 52435 | 15 December 2016 11:10:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Alert Declared - Catastrophic Failure of an Emergency Diesel Generator | The following event description is based on information currently available. If through subsequent reviews of this event additional information is identified that is pertinent to this event or alters the information being provided at this time a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. During a scheduled surveillance test run of the PVNGS (Palo Verde Nuclear Generating Station) Unit 3 'B' Train Emergency Diesel Generator, there was a catastrophic failure of a piston to include crankcase damage and diesel trip. The Emergency Plan has been entered and an ALERT was declared at 0410 (MST) on 12/15/16 based on an explosion resulting in visible damage to a safety system required for safe shutdown. The cause of the failure is unknown at this time. PVNGS Fire Department responded and no fire was observed. Unit 3 remains on line at 100% power. No other safety functions are impacted. No personnel injuries occurred. The unit is in a ten day technical specification on an emergency diesel generator being inoperable. The licensee notified the NRC Resident Inspector. Notified DHS, DOE, EPA, FEMA, NICC, USDA, HHS, FDA, NSSA, Mexico, and OIP (Skeen).
This serves as the notification of the termination of Alert HA2.1 declared at 0410 MST at Palo Verde Nuclear Generation Station. The event terminated at 0636 MST. The licensee will notify the NRC Resident Inspector. Notified R4DO (Keller), NRR EO (Miller), IRD (Stapleton), DHS, DOE, EPA, FEMA, NICC, USDA, HHS, FDA, NSSA, Mexico, and OIP (Skeen). | Emergency Diesel Generator | |
ENS 51522 | 9 November 2015 12:47:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Containment Fire Alarm | The following event description is based on information currently available. If through subsequent reviews of this event additional information is identified that is pertinent to this event or alters the information being provided at this time a follow-up notification will be made via the ENS or under the reporting requirements of 10 CFR 50.73. During Palo Verde Nuclear Generating Station Unit 2 containment pressurization for integrated leak rate testing in Mode 5, a containment fire alarm in Fire Zone 63B (Steam Generator 2 all elevations of containment) was received. Containment temperature and pressure at time of event were 72 degrees F and 13 PSIG. Due to the inability to access containment to validate the fire alarm, an Unusual Event (HU2.1) was declared at 0547 (MST) for a Fire in containment which was unable to be validated within 15 minutes of receipt. No safety functions have been impacted due to the fire alarm. No automatic or manual RPS or ESF actuations occurred and none were required. Actions are being taken to depressurize containment to enter and validate the fire alarm. The NRC Resident Inspector has been notified. There has been no effect on U-1 or U-3 due to this fire alarm. Notified DHS SWO, FEMA Ops Center, NICC Watch Officer and via E-mail only FEMA NWC and Nuclear SSA.
Containment was entered following depressurization. Operations and Fire Protection personnel inspection of containment and Fire Zone 63B identified no indication of fire or smoke and the fire alarm was determined to be invalid. No other impacts to plant equipment were identified. The Unusual Event was terminated on 11/9/2015 at 0901 MST. The NRC Resident Inspector has been notified. Notified R4DO (Proulx), NRR EO (Morris), and IRD (Grant). Notified DHS SWO, FEMA Ops Center, NICC Watch Officer and via E-mail only FEMA NWC and Nuclear SSA. | Steam Generator | |
ENS 51403 | 17 September 2015 06:01:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event Due to Rapid Combustion of a Load Center Breaker | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event, or alters the information being provided at this time a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. Non Class Load Center Breaker, 2ENGN-L04 failed, resulting an a visible observation of rapid combustion and resultant charring (burned area) of the breaker enclosure and housing. No physical deformation to the breaker housing or surrounding area has been identified. The rapid combustion self-extinguished immediately following the audible and visible combustion event. As a result, an Emergency Classification of HU2.2, EXPLOSION was declared due to the Load Center breaker failure and noise and visible indication observed in the field. The plant was, and continues to operate at 100% full power operations on normal power alignment. The 2ENGN-L04 Non-Class Load Center breaker supplies power to non-essential service loads and has no immediate impact to plant operation or safety mitigating systems. The plant remains stable and the event did not adversely affect the safe operation of the plant or health and safety of the public. The NRC Resident Inspector has been notified. Notified DHS SWO, DHS NICC, FEMA, and Nuclear SSA via email.
PVNGS Unit 2 terminated the Unusual Event HU2.2 on 9/17/15 at 04:04 MST. Non-Class load center 2ENGN-L04 has been isolated and de-energized. There was no reflash or fire at the breaker and no hazard to plant personnel exists. Damage appears to be limited to the NGN-L04D3 breaker cubicle and a spare breaker cubicle below NGN-L04D3. There was no damage to any safety related equipment. The licensee will be notifying the state of Arizona, Maricopa County authorities and the NRC Resident Inspector. Notified R4DO (Farnholtz), NRR EO (Morris), IRD MOC (Gott), DHS SWO, FEMA Ops, DHS NICC and NuclearSSA (email). | ||
ENS 50237 | 29 June 2014 05:06:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event - Earthquake Felt on Site | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. An event classification of Unusual Event (HU1.1) was declared at 22:17 MST for the Palo Verde Nuclear Generating Station because of an earthquake that originated 50km NW of Lordsburg, New Mexico at 21:59 MST. Per the USGS website, the magnitude of the earthquake was 5.2 on the Richter scale. Initial walkdowns of plant equipment and review of plant parameters have found no unusual conditions or damage to plant equipment. No abnormalities caused by the seismic event were observed. No reactor protection system (RPS) or engineered safety feature (ESF) actuations occurred and none were required. Palo Verde Unit 1, 2, and 3 are at 100 percent power with all offsite power supplies available. Initial analysis of the Seismic Monitoring Instrumentation System indicated a seismic event, below the magnitude of the 0.10g spectra Operating Basis Earthquake (OBE) and the 0.20g spectra Safe Shutdown Earthquake (SSE). The NRC Resident Inspector has been notified of seismic activity and this ENS call. This event time is 2206 MST because this is the time the control room was notified by plant Operators that an earthquake had been felt on site. Notified DHS, FEMA, and NICC. FEMA NWC and Nuclear SSA were notified via email.
Emergency classification termination was declared at 6/29/14 01:12 MST. All required power block inspections were completed with no deficiencies noted. No other conditions require an emergency classification, there are no challenges to fission product barriers or radiological release, and plant conditions offer no possibility of adverse impact on health and safety of the public. The licensee notified the NRC Resident Inspector, state and local governments. Notified the R4DO (Allen), NRR (Hiland), IRD (Gott), DHS, FEMA, and NICC. FEMA NWC and Nuclear SSA were notified via email. | Reactor Protection System | |
ENS 49317 | 3 September 2013 02:26:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Fire in the Turbine Building | An Event Classification of Unusual Event (HU2.1) was declared at 1926 (MST) for the Palo Verde Nuclear Generating Station. At 1912, smoke was detected by a security officer by the 'A' train Main Feed pump. An Auxiliary Nuclear Operator investigated and identified a fire on lagging, with one foot flames behind the main standard 'A' train Main Feed pump. The fire team responded to the fire and is currently on scene. Fire was declared out at 1957. No reactor protection system (RPS) or engineered safety feature (ESF) actuations occurred and none were required. The event did not result in any challenges to the fission product barrier or result in any releases of radioactive materials. There were no adverse safety consequences, and this event did not adversely affect the safe operation of the plant or health and safety of the public. The 'A' Main Feed pump high vibration alarm was received, but the continued operation of the main feed pump is currently not in jeopardy. While removing lagging, during the recovery process, the licensee had 2 reflash events. The flame was extinguished and the licensee continues to remove the oil soaked lagging for the 'A' Main Feed pump. The licensee has notified the NRC Resident Inspector, State, and Local Authorities. The Tonopah Fire Department was contacted and did respond to the site. Notified DHS SWO, FEMA, DHS NICC, and Nuclear SSA (email only).
PVNGS Unit 2 Terminated the Unusual Event HU2.1 on 9/3/13 at 0029 MST. The fire no longer constitutes a hazard to plant or personnel. 'A' Main Feed Pump is running and Unit 2 is operating at 100% power. The fire was extinguished at 1957 MST (per fire team advisor) and was declared extinguished by the incident commander at 2055 MST. A small oil vapor leak was identified coming from the high pressure bearing seal. Vapor extraction differential pressure was increased to eliminate the oil vapor leak. At 2134 MST, received a report of two reflash events while the Fire Department was removing additional lagging with no sustained flame or fire. All the affected lagging has been removed and the fire emergency was terminated at 2345 MST on 9/2/13. The licensee updated event times to reflect MST. The licensee has notified the NRC Resident Inspector, State, and Local Authorities. Notified R4DO (Hagar), NRR (Galloway), IRD (Marshall), DHS SWO, FEMA, DHS NICC, and Nuclear SSA (email only). | Reactor Protection System | |
ENS 49169 | 3 July 2013 07:00:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notice of Unusual Event Due to Explosion in a Non-Safety Related Load Center | The following event description is based on information currently available. If through subsequent reviews of this event additional information is identified that is pertinent to this event or alters the information being provided at this time a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. On 7/2/2013, at approximately 2027 MST, Palo Verde Unit 1 experienced a reactor power cutback from 100% rated thermal power due to explosion (in a non-safety related load center (1ENGNL02)). The unit was at normal temperature and pressure prior to the cutback. At 2035 (MST) PVNGS Unit 1 declared an Unusual Event due to the explosion EAL HU 2.2. Unit 1 is stable at 61% rated thermal power. No ESF actuations occurred and none were required. The event did not result in any challenges to the fission product barrier or result in any releases of radioactive materials. There were no adverse safety consequences or implications as a result of this event. The event did not adversely affect the safe operation of the plant or health and safety of the public. The licensee will notify the NRC Resident Inspector. Notified DHS SWO, FEMA, DHS NICC, and Nuclear SSA via email. * * * UPDATE ON 7/3/13 AT 0229 EDT FROM JEONG LIM TO PETE SNYDER * * * Palo Verde Unit 1 is stable at 58% rated thermal power and is implementing abnormal operating procedures for reactor power cutback due to loss of one Main Feedwater Pump and degraded electrical power due to loss of non-class 13.8kV load center 1ENGNL02. Load center 1ENGNL02 was damaged from an apparent electrical malfunction that originated within the load center. The 13.8kV supply breaker to load center 1ENGNL02 tripped to deenergize the load center. Palo Verde Fire Department personnel responded but determined that the load center was deenergized and no fire existed and no extinguishing agents were applied. No damage to other equipment in proximity to load center 1ENGNL02 was identified during a preliminary inspection of the area around the damaged load center. The NRC Resident Inspector has been notified. At 2315 (MST) on 07/02/2013, the Unusual Event was terminated. Notified R4DO (Gaddy), NRR EO (Nieh), IRD MOC (Gott), DHS SWO, FEMA, DHS NICC, and Nuclear SSA via email. | Feedwater | |
ENS 47333 | 8 October 2011 23:19:00 | 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 Due to Severe Electrical Fault in Rcp Junction Box | Reactor Coolant Pump 2A tripped at approximately 1535 MST, resulting in numerous simultaneous electrical distribution alarms. A walkdown of containment was performed and at 1609 MST it was determined that a junction box, supplying power to the 2A Reactor Coolant Pump, had failed, resulting in the pump tripping on overcurrent protection and an 86 lockout. The plant was operating in forced circulation and had one train of shutdown cooling in service. As a result, an Emergency Classification of HU2.2, Explosion was declared due to the junction box failure and noise that had been heard in containment. The plant is currently stable with one train of shutdown cooling in service, the opposite train of shutdown cooling is available to be placed in service. The Unit 1 Reactor Coolant System is currently at 160 degrees Fahrenheit and 375 psia with the 1A Reactor coolant pump in service for forced circulation. The event did not result in the release of radioactivity to the environment and did not adversely affect the safe operation of the plant or health and safety of the public. The NRC Resident Inspector has been notified. The licensee has notified appropriate state and local agencies.
The Notification of Unusual Event at Palo Verde Unit 1 was terminated at 1916 MST on 10/8/2011. The termination was based on conducting inspections which did not reveal any additional damage or plant impact as a result of this event. Unit 1 remains stable in Mode 5 with RCPs 1A and 1B in service along with one train of RHR in service. The licensee notified the NRC Resident Inspector and appropriate state and local agencies. Notified R1DO (Gray), NRR EO (Hiland), IRD (Grant), DHS (Flinter), and FEMA (Castro). | Reactor Coolant System Shutdown Cooling | |
ENS 46025 | 18 June 2010 15:08:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Damaged Energized Equipment | On June 18, 2010, at approximately 0807 MST, a manual turbine trip was initiated due to loss of cooling for Main Transformer X01C. The power supplies for the transformer cooling system was lost due to an inadvertent actuation of the transformer fire protection deluge system. The damage to the energized equipment met the definition for an Emergency Action Level HU 2.2. Based on HU 2.2 the Unit 1 Shift Manager declared a Notification of an Unusual Event (NOUE) at 0808 MST applicable to Palo Verde Unit 1 only. The manual trip of the turbine initiated a Reactor Power Cutback Large Load Rejection actuation which was successful. The reactor is stable at 25% with Heat Removal via main feedwater and steam bypass to main condenser. A down power to approximately 12% power is being planned. No anomalies were noted during the manual turbine trip. (There is) no release in progress and no safety systems actuations were required. Palo Verde Unit 1 is in a normal post-trip electrical lineup. State and local authorities have been notified as well as the NRC Resident Inspector.
The licensee terminated the Unusual Event at 1030 MST. The reactor remains stable at approximately 12% power, and heat removal is via main feedwater and steam bypass to the main condenser. Notified IRD (Gott), NRR EO (Cheok), R4DO (Jones), DHS (Inzer) and FEMA (Hollis). | Feedwater Main Transformer Main Condenser | |
ENS 45823 | 8 April 2010 17:15:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Earthquake | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under reporting requirements of 10 CFR 50.73. An Event Classification of Unusual Event (HU1.1) was declared at 10:15 MST for the Palo Verde Nuclear Generating Station because of an earthquake that originated in Baja California location 32.220 N, 115.276 W at 09:44 MST. Per the USGS website and via phone conversation at 10:03, the magnitude of the earthquake was preliminarily 5.5 on the Richter scale. Initial walk downs of plant equipment and review of plant parameters have found no unusual conditions or damage to plant equipment. No abnormalities caused by the seismic event were observed. No reactor protection system (RPS) or engineered safety feature (ESF) actuations occurred and none were required. Palo Verde Unit 1 is in mode 6 for a scheduled refueling outage and Units 2 & 3 are at 100 percent power with all offsite power supplies available. Seismic Monitoring Instrumentation system is currently functional and did not indicate a seismic event. Currently based on the Modified Mercalli scale the seismic event was below the magnitude of the 0.10g spectra Operating Basis Earthquake (OBE) and the 0.20g spectra Safe Shutdown Earthquake (SSE). The licensee notified the NRC Resident Inspector. * * * UPDATE FROM JIM BLAZEK TO PETE SNYDER AT 1606 ON 4/8/10 * * * Emergency classification termination was declared at 4/08/10, 12:54 MST. All required power block inspections were completed with no deficiencies noted. No other conditions required an emergency classification, there are no challenges to fission product barriers or radiological release, and plant conditions offer no possibility of adverse impact on health and safety of the public. The NRC Resident Inspector has been notified of NUE termination. Notified R4DO (Proulx), NRR EO (Thorp), DPR (McDermott), DHS (McDonald), and FEMA (Hollis). | Reactor Protection System | |
ENS 45811 | 4 April 2010 22:42:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to an Earthquake | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. An Event Classification of Unusual Event (HU1.1) was declared at 1549 MST for the Palo Verde Nuclear Generating Station because of an earthquake that originated in Baja California, (Mexico) location 32.093?N, 115.249?W at 1542 MST. Per the USGS (U.S. Geological Survey) website, the magnitude of the earthquake was 6.9 on the Richter scale. Initial walkdowns of plant equipment and review of plant parameters have found no unusual conditions or damage to plant equipment. No abnormalities caused by the seismic event were observed. No Reactor Protection System (RPS) or Engineered Safety Feature (ESF) actuations occurred and none were required. Palo Verde Unit 1 is in mode 5 for a scheduled refueling outage, and Units 2 & 3 are at 100 percent power with all offsite power supplies available. Initial analysis of the Seismic Monitoring Instrumentation system indicated a seismic event, below the magnitude of the 0.10g spectra Operating Basis Earthquake (OBE) and the 0.20g spectra Safe Shutdown Earthquake (SSE). The licensee has notified the NRC Resident Inspector.
Emergency classification termination was declared at 4/4/10, 2045 MST. All required power block inspections were completed with no deficiencies noted. No other conditions require an emergency classification, there are no challenges to fission product barriers or radiological release, and plant conditions offer no possibility of adverse impact on health and safety of the public. NRC Resident Inspector has been notified of NUE termination. Notified the R4DO (Okeefe), NRR-EO (Bahadur), FEMA (Via), DHS (Wallace) and IRD via email (Gott). | Reactor Protection System | |
ENS 45784 | 23 March 2010 01:11:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event Due to Unidentified Leakage Greater than 10 Gpm | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirement of 10CFR50.73. On March 22, 2010 at approximately 1756 MST, Palo Verde Nuclear Generating Station (PVNGS) Unit 1 identified a rising level and temperature trend in the Reactor Drain Tank (RDT). PVNGS Unit 1 was in Mode 1 (Power Operation) at 93% power with normal RCS temperature and pressure at the time of discovery. Containment temperature and humidity trends are normal. Technical Specification Limiting Condition for Operation 3.4.14 (RCS Operational Leakage), Condition 'A' was entered at 1811 due to unidentified leakage >10 gpm and the LCO allows 4 hours to restore leakage to <1 gpm. Also at 1811, a Notification of Unusual Event (NOUE) was declared due to unidentified leakage >10 gpm (MU5.1). PVNGS Unit 1 remains at power with all normal systems in operation; periodic pumping of the RDT is occurring. No automatic or manual reactor protection system or engineered safety features actuations occurred and none were required. There were no other component failures, testing or work in progress that contributed to the leak. The leak is located within the containment building, therefore there is no release of radioactivity to the environment and no impact to the health and safety of the public. There is no elevated RCS activity and heat removal is via normal steaming to the main turbine condenser. The electric grid is stable. Current plans are to enter containment and identify the source of leakage. State and Local authorities have been notified. The NRC Senior Resident Inspector has been notified. The licensee notified the following state and local agencies: Maricopa County Sheriff, Arizona Department of Public Safety, Buckeye Police Department, Arizona Radiation Regulatory Agency, Arizona Division of Emergency Management, and the Maricopa County Emergency Management Agency.
At 2112 MST, the shift manager advised that the Pressurizer Main Spray Valve, 100E, packing leakage has been manually isolated. As of 2125 MST, the level trend in the RDT has stabilized. The licensee is working to verify the leakage rate, and remains in an Unusual Event. The plant remains stable in Mode 1 at 93% power. The licensee has notified the NRC Resident Inspector, and the NRC Resident Inspector remains on site.
At 2146 MST, the licensee exited Technical Specification Limiting Condition for Operation 3.4.14, RCS Operational Leakage. At 2219 MST, the Unusual Event was terminated. The licensee will notify the NRC Resident Inspector. Notified R4DO (Deese), NRR EO (Brown), IRD (McDermott), DHS (Moore), and FEMA (Canupp). | Reactor Protection System Main Turbine | |
ENS 45748 | 7 March 2010 18:24:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event Due to Electrical Fault Causing Damage to Equipment | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. On March 7, 2010, at approximately 1124 MST Palo Verde Unit 1 declared a Notification of Unusual Event (NOUE) due to an electrical fault (explosion) experienced on the 13.8 KV Non-Class busses being supplied from the Unit Auxiliary Transformer. The fault resulted in a minor explosion and damage to the bus work leading from NAN S03 to NAN S01. The fault resulted in the loss of the NAN S01, which caused a reactor trip due to the loss of 2 of 4 reactor coolant pumps. There was no fire detected after the initial event. The reactor trip (RPS actuation at 1117 MST) was from 100% rated thermal power due to low departure from nucleate boiling (DNBR) trips on all four channels of the core protection calculators (CPCs). The unit was at normal temperature and pressure prior to the trip. All of the control rods fully inserted into the core. Four of eight steam bypass control valves quick opened, per design, directing steam flow to the condenser. No main steam or primary relief valves lifted and none were required. There was no loss of heat removal capability or loss of safety functions associated with the event. ESF Electrical buses remain energized from off-site power. The Shift Manager determined this event was an uncomplicated reactor trip. No significant LCOs have been entered as a result of this event. No major equipment was inoperable prior to the event nor contributed to the event. Unit 1 is stable at normal operating temperature and pressure in Mode 3. No ESF actuations (other than RPS) occurred and none were required. The event did not result in any challenges to the fission product barrier or result in any releases of radioactive materials. There were no adverse safety consequences or implications as a result of this event. The event did not adversely affect the safe operation of the plant or health and safety of the public. Decay heat is being removed via the steam bypass valves to the condenser. The plant is in its normal shutdown electrical lineup with the exception of powering the NAN S01 bus. Unit 2 and Unit 3 were not affected by the transient on Unit 1. The licensee has notified the NRC Resident Inspector.
Palo Verde Unit 1 has terminated the NOUE at 1516 MST. The termination criteria was that the plant is stable, the area around the fault has been inspected and no other conditions exist that would prevent termination of the event. Decay heat path has been changed from steam dumps to condenser to atmospheric dumps due to difficulty in maintaining temperature. There is no known primary to secondary leakage. The licensee has notified the NRC Resident Inspector. Notified R4DO (Cain), NRR EO (Holian), IRD (Gott), DHS (Roper) and FEMA (LaForte). | Control Rod Main Steam | 05000528/LER-2010-001 |
ENS 43764 | 2 November 2007 14:44:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Suspicious Explosive Device Discovered in Vehicle at Oca Access Checkpoint | On November 2, 2007 at 0744 (MST), Palo Verde Nuclear Generating Station Units 1, 2 and 3 declared a Notification of an Unusual Event as specified in the Emergency Plan. The basis for the Emergency Class declaration was detection of a credible threat: an explosive device was detected during a vehicle search at the site access check point. The site has entered its Deliberate Acts procedure. The device was discovered in a contract employee's vehicle at 0525 MST. It was confirmed to be an explosive device at 0730 MST by the Maricopa County Sheriff's Office (MCSO). The explosive device was removed from the site by MCSO and Federal Bureau of Investigation (FBI) at 0852. The individual driving the vehicle has been detained by MCSO. No other individuals were in the vehicle at the time. Palo Verde Unit 1 is in Mode 2 at approximately 2% power. Unit 2 is in Mode 1 at 100% power. Unit 3 is defueled undergoing steam generator replacement. No reactor protection system or engineered safety feature system actuations have occurred and none are required. No major structures, systems, or components are inoperable impacting the continued safe operation of the units. Plans are to continue Mode 2 operations in Unit 1 and Mode 1 full power operation in Unit 2. Further investigation is ongoing in cooperation with MCSO and the FBI. Security is conducting searches of the site. No additional concerns have been identified at this time. The security event has not resulted in any challenges to the fission product barrier or result in any releases of radioactive materials. There were no adverse safety consequences or implications as a result of the security event declaration. A news release was made at 11:10 a.m. The licensee notified the NRC Resident Inspector.
At 1447 MST site security posture has changed from Code Red to Code Yellow Heightened Awareness, and at 1504 MST licensee exited the Unusual Event,. The licensee has notified the NRC Resident Inspector, state and local agencies, and will be issuing a press release this evening. Notifications were given to the following: R4 (Art Howell), R4DO(Powers), NRR EO (Bateman), IRD Manager (Blount), ILTAB (Sandler), DHS (York), FEMA (Dunker), DOE (Wyatt), FBI-SIOC (Curry), HHS (White), USDA (Phillip).
The licensee downgraded the security posture at the site from Code Yellow Heightened Awareness to Code Yellow. The licensee notified the NRC Resident Inspector. Notified R4DO (Powers) and ILTAB (Sandler).
Arizona Public Service Company (APS) is retracting security-related Event Notification #43764 and notification of unusual event (NUE) reported on November 2, 2007. Based upon investigations performed by the Federal Bureau of Investigation (FBI), Maricopa County Sheriff's Office (MCSO) and Palo Verde Security department, APS has determined that there was no explicit nor credible threatened action as described in 10 CFR 73.71, Appendix G, Paragraph I. These investigations revealed that the previously reported explosive device was placed in the owner's truck bed without his knowledge. Therefore, there is no reason to believe that a person has committed or caused, or attempted to commit or cause, or has made a credible threat to commit or cause: theft or unlawful diversion of special nuclear material; or significant physical damage to a power reactor; or interruption of normal operation of a licensed nuclear power reactor. The licensee notified the NRC Resident Inspector. R4DO (Farnholtz) has been notified and an e-mail sent to ILTAB and the 73.71 group. | Steam Generator Reactor Protection System | |
ENS 40814 | 14 June 2004 14:44:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 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 | Alert Declared - Reactor Trip Due to Loss of Off Site Power | On June 14, 2004, at approximately 07:44 Mountain Standard Time (MST) all three units at the Palo Verde Nuclear Generating Station experienced automatic reactor trips coincident with a grid disturbance and loss of offsite power in the Palo Verde Switchyard. Unit 2 declared an ALERT Emergency Plan classification at approximately 07:54 due to a loss of AC power to essential buses reduced to a single power source for greater than 15 minutes such that any additional single failure would result in a station blackout. Subsequently, at 09:51 Unit 2 downgraded the Emergency Plan classification to a NOTIFICATION OF UNUSUAL EVENT when AC power was restored from a single essential bus to both essential buses. Units 1 and 3 declared a NOTIFICATION OF UNUSUAL EVENT at 07:53 MST due to a loss of offsite power to essential buses for greater than 15 minutes. The NOTIFICATION OF UNUSUAL EVENT was terminated for all 3 units at 12:07 MST. Unit 1 and 2 manually initiated a Main Steam Isolation System ESF actuation by procedure. Unit 3 received an automatic Main Steam Isolation System ESF actuation. Due to the loss of offsite power, the Emergency Plan Technical Support Center (TSC) was unavailable. The Unit 2 Satellite TSC was to be staffed by the Emergency Response Organization in response to the loss of assessment capability. Power to the TSC has since been restored. The Emergency Plan ALERT declaration includes staffing of the Joint Emergency New Center to address expected media interest. All three units were at normal operating temperature and pressure prior to the trip. All CEAs inserted fully into the reactor cores. All Emergency Diesel Generators (EDGs) (2 per unit) associated with each of the 3 units started as expected in response to the loss of offsite power to their safety buses. Unit 2's train "A" EDG started, but did not indicate volts or amps and was manually shutdown. The offsite power grid had several perturbations for approximately one hour following the event but has been stable since. LCO 3.8.1, AC Sources - Operating, was entered in each unit as a result of this event. Heat removal is to atmosphere via atmospheric dump valves in natural circulation. Main steam safety valves may have lifted for a brief time. Restoration of forced reactor coolant circulation is pending assurance that the offsite power grid can reliably support the load. No major equipment was inoperable prior to the event that contributed to the event. All 3 units are stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant NRC Resident Inspector was notified. FBI Jeff Muller and Mr. Rosales (Mexican National Commission of Nuclear Safety and Safeguards (CNSNS)) were notified.
Notified Reg 4 RDO (Graves), NRR (Bateman), DHS (Lee), FEMA (Canupp), DOE (Sal Moroni), EPA (Stalcup), EPA (Crews), HSS (Davidson), and Mexico (Rosales) NOTE: See events 40815, 40816 and 40818 | Emergency Diesel Generator Main Steam Safety Valve Main Steam | |
ENS 40816 | 14 June 2004 14:44:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 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 Due to Reactor Trip Due to Loss of Off Site Power | On June 14, 2004, at approximately 07:44 Mountain Standard Time (MST) all three units at the Palo Verde Nuclear Generating Station experienced automatic reactor trips coincident with a grid disturbance and loss of offsite power in the Palo Verde Switchyard. Unit 3 declared a NOTIFICATION OF UNUSUAL EVENT at 07:53 MST due to a loss of offsite power to essential buses for greater than 15 minutes. The NOTIFICATION OF UNUSUAL EVENT was terminated at 12:07 MST. Unit 3 received an automatic Main Steam Isolation System ESF actuation. Due to the loss of offsite power, the Emergency Plan Technical Support Center (TSC) was unavailable. The Unit 2 Satellite TSC was to be staffed by the Emergency Response Organization in response to the loss of assessment capability. Power to the TSC has since been restored. The unit was at normal operating temperature and pressure prior to the trip. All CEAs inserted fully into the reactor cores. All Emergency Diesel Generators (EDGs) (2 per unit) associated with the unit started as expected in response to the loss of offsite power to their safety buses. The offsite power grid had several perturbations for approximately one hour following the event but has been stable since. LCO 3.8.1, AC Sources - Operating, was entered as a result of this event. Heat removal is to atmosphere via atmospheric dump valves in natural circulation. Main steam safety valves may have lifted for a brief time. Restoration of forced reactor coolant circulation is pending assurance that the offsite power grid can reliably support the load. No major equipment was inoperable prior to the event that contributed to the event. The Unit is stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant NRC Resident Inspector was notified. FBI Jeff Muller and Mr. Rosales (Mexican National Commission of Nuclear Safety and Safeguards (CNSNS)) were notified.
Notified Reg 4 RDO (Graves), NRR (Bateman), DHS (Lee), FEMA (Canupp), DOE (Sal Moroni), EPA (Stalcup), EPA (Crews), HSS (Davidson), and Mexico (Rosales) Note: see related events 40815 , 40814 and 40818 | Emergency Diesel Generator Main Steam Safety Valve Main Steam | |
ENS 40815 | 14 June 2004 14:44:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 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 Reactor Trip Due to Loss of Off Site Power | On June 14, 2004, at approximately 07:44 Mountain Standard Time (MST) all three units at the Palo Verde Nuclear Generating Station experienced automatic reactor trips coincident with a grid disturbance and loss of offsite power in the Palo Verde Switchyard. Unit 1 declared a NOTIFICATION OF UNUSUAL EVENT at 07:53 MST due to a loss of offsite power to essential buses for greater than 15 minutes. The NOTIFICATION OF UNUSUAL EVENT was terminated at 12:07 MST. Unit 1 manually initiated a Main Steam Isolation System ESF actuation by procedure. Due to the loss of offsite power, the Emergency Plan Technical Support Center (TSC) was unavailable. The Unit 2 Satellite TSC was to be staffed by the Emergency Response Organization in response to the loss of assessment capability. Power to the TSC has since been restored. The unit was at normal operating temperature and pressure prior to the trip. All CEAs inserted fully into the reactor cores. All Emergency Diesel Generators (EDGs) (2 per unit) associated with the unit started as expected in response to the loss of offsite power to their safety buses. The offsite power grid had several perturbations for approximately one hour following the event but has been stable since. LCO 3.8.1, AC Sources - Operating, was entered as a result of this event. Heat removal is to atmosphere via atmospheric dump valves in natural circulation. Main steam safety valves may have lifted for a brief time. Restoration of forced reactor coolant circulation is pending assurance that the offsite power grid can reliably support the load. No major equipment was inoperable prior to the event that contributed to the event. The Unit is stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant NRC Resident Inspector was notified. FBI Jeff Muller and Mr. Rosales (Mexican National Commission of Nuclear Safety and Safeguards (CNSNS)) were notified.
Notified Reg 4 RDO (Graves), NRR (Bateman), DHS (Lee), FEMA (Canupp), DOE (Sal Moroni), EPA (Stalcup), EPA (Crews), HSS (Davidson), and Mexico (Rosales) Note: see related events # 40814, 40816 and 40818 | Emergency Diesel Generator Main Steam Safety Valve Main Steam |