Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 55796 | 19 March 2022 20:06:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Technical Support Center (TSC) | The following information was provided by the licensee via email: 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. At 1306 (MST) on March 19, 2022, the Technical Support Center (TSC) lost normal and alternate electrical power, resulting in the inability to perform emergency assessments at the TSC. At the time of the event, the normal power source to the TSC (offsite power) was under a clearance for maintenance activities and the alternate power source (backup generator) was running to provide electrical power to the TSC. At 1306, the alternate power source to the TSC was lost when the backup generator tripped. Power was restored to the TSC via the normal power source at 1723. The cause of the TSC backup generator trip is unknown at this time. All three units are stable and in Mode 1. No emergency classification was required per the Emergency Plan. The NRC Senior Resident Inspector has been informed. | ||
| ENS 55444 | 1 September 2021 03:50:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Seismic Monitoring System | 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. On 8/31/21 at 2050 (MST), the Seismic Monitoring System was discovered Non-Functional. This constitutes an unplanned loss of emergency assessment capability for an operational basis earthquake. There is currently no seismic activity in the area according to the U.S. Geological Survey. The NRC Resident Inspector was notified of the loss of seismic monitoring capability. | ||
| ENS 54272 | 12 September 2019 01:24:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Main Steam Line Radiation Monitor Communication Failure | 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. Radiation monitor RU-140 (#2 Steam Generator Main Steam Line radiation monitor) experienced a communication failure on both ports A and B. The RU-140 monitor is off line and non-functional at this time. At least one channel of RU-140 is required to perform a Steam Generator Tube Rupture (SGTR) dose assessment. This represents an unplanned loss of radiological assessment capability for the inability to perform dose assessments that require the radiation monitor. The ability to make emergency classifications from other radiological data collection methods such as field sampling remains available. Actions have been initiated to restore the radiation monitor. The NRC Resident Inspector has been informed. | Steam Generator Main Steam Line | |
| ENS 53575 | 31 August 2018 07:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Unplanned Loss of Steam Line Monitor Channels | 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. This event is being reported pursuant to 10 CFR 50.72(b)(3)(xiii) as a Loss of Emergency Preparedness Capabilities at Palo Verde Nuclear Generating Station (PVNGS) Unit 2. On August 31, 2018, at approximately 0544 Mountain Standard Time (MST), the Unit 2 control room experienced an unplanned loss of Steam Generator #1 steam line monitor (RU-139), Channels A and B. This main steam line monitor is used in the PVNGS Emergency Plan to perform dose assessment in the event of a steam generator tube rupture. The NRC Resident Inspectors have been notified. | Steam Generator Main Steam Line | |
| ENS 53522 | 23 July 2018 07:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Unplanned Loss of Steam Line Monitor Channels | 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 (Emergency Notification System) or under the reporting requirements of 10CFR50.73. This event is being reported pursuant to 10CFR50.72(b)(3)(xiii) as a Loss of Emergency Preparedness Capabilities at Palo Verde Nuclear Generating Station (PVNGS) Unit 2. On July 23, 2018, at approximately 1631 Mountain Standard Time (MST), the Unit 2 control room experienced an unplanned loss of Steam Generator #1 steam line monitor (RU-139), channels A and B. This monitor is used to assess dose projections for Main Steam line exhaust while in Modes 1-4 and is used in the PVNGS Emergency Plan to perform classification of Initiating Conditions 'RS1' and' RG1' and Emergency Action Levels (EALs) 'RS1.2' and 'RG1.2'. The PVNGS Emergency Plan does have two additional EALs that can be assessed for each Initiating Condition. The loss of this monitor constitutes a reportable loss of emergency assessment capability. The NRC Resident Inspector has been informed of this condition. | Steam Generator Main Steam Line | |
| ENS 53215 | 16 February 2018 04:53:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Automatic Reactor Trip Due to Low Departure from Nucleate Boiling Signal | 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 February 15, 2018, at approximately 2153 Mountain Standard Time (MST), the Palo Verde Nuclear Generating Station (PVNGS) Unit 1 Control Room received Reactor Protection System alarms for Low Departure from Nucleate Boiling Ratio and an automatic reactor trip occurred. Prior to the reactor trip, Unit 1 was operating normally at 100 percent power. Plant operators entered the emergency operations procedures and diagnosed an uncomplicated reactor trip but noted that Reactor Coolant Pumps 1B and 2B were not running due to a loss of power. All CEAs (Control Element Assemblies) fully inserted into the core. Following the reactor trip, all nuclear instruments responded normally. No emergency classification was required per the PVGS Emergency Plan. The PVGS Unit 1 safety related electrical busses remained energized from normal offsite power during the event. The Unit 1 'B' Diesel Generator is currently removed from service for maintenance. Due to ongoing planned maintenance on NAN-X02, Startup Transformer 2, fast bus transfer for NAN-S02 (from NAN-S04) was blocked. This resulted in a loss of offsite power to NAN-S02 and NBN-S02. The offsite power grid is stable. Unit 1 is currently stable in Mode 3 with the reactor coolant system at normal operating temperature and pressure. 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 or the health and safety of the public. The NRC Resident Inspector has been informed of the Unit 1 reactor trip.
Unit 1 is stable in Mode 3 following an uncomplicated trip. Offsite power has been restored to non-safety related electrical busses. Troubleshooting continues to determine the cause of the event. During performance of the alarm response procedure, it was identified that the seismic monitoring (SM) system had been in alarm since the reactor trip and was incapable of performing its emergency plan function. Pursuant to 10 CFR 50.72(b)(3)(xiii), this condition constitutes a major loss of emergency assessment capability. Compensatory measures have been implemented in accordance with PVNGS procedures to provide alternative methods for HU2.1 event classification with the SM system out of service. Maintenance is currently in progress to restore SM system functionality. The licensee notified the NRC Resident Inspector. Notified R4DO (Werner).
Station staff completed an evaluation of event EN #53215 reported on February 15, 2018, and determined that the seismic monitoring system remained capable of assessing a seismic event following the reactor trip. Therefore, a major loss of emergency assessment capability pursuant to 10 CFR 50.72(b)(3)(xiii) did not occur as reported in the update on February 16, 2018. The NRC Resident Inspectors have been notified. Notified the R4DO (Gaddy). | Reactor Coolant System Reactor Protection System | |
| ENS 52989 | 22 September 2017 22:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Seismic Monitoring Computer Out-Of-Service | 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. This event is being reported pursuant to 10 CFR 50.72(b)(3)(xiii) for a major loss of emergency assessment capability at the Palo Verde Nuclear Generating Station (PVNGS). On September 21, 2017 at 0915 MST, the seismic monitoring (SM) computer was declared non-functional for the performance of a planned surveillance test. On September 21, 2017 at 1201 MST, the SM system computer became non-responsive during the performance of the test. Control room staff attempted to reboot the computer and were unsuccessful. Maintenance and troubleshooting efforts began thereafter to initiate repairs. As a compensatory measure, PVNGS procedures for seismic event evaluation provide alternative methods for event classification of a seismic event with the SM system out of service. The SM system functions to provide indication that the Operational Basis Earthquake (OBE) threshold has been exceeded following a seismic event and is used in the PVNGS Emergency Plan to perform classification of Initiating Condition 'Seismic event greater than OBE levels' and Emergency Action Level HU2.1. On September 22, 2017 at 1500 MST, maintenance personnel performing software repair efforts determined hardware replacement is required. The required component will not be available before 72 hours from the start of the event. Because the SM system is not expected to be restored within 72 hours, this condition is being reported as a planned event constituting a major loss of emergency assessment capability with viable compensatory measures in place. The NRC Resident Inspector has been informed of this condition. | ||
| ENS 52229 | 9 September 2016 01:56:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of the Seismic Monitoring System Computer | 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. This event is being reported pursuant to 10 CFR 50.72(b)(3)(xiii) for a loss of emergency assessment capability at the Palo Verde Nuclear Generating Station (PVNGS). On September 8, 2016 at 1856 (MST), seismic monitoring (SM) system computer AJSMNXYQI0001**INSTRU was determined to be non-functional due to a power spike which caused a temporary loss of power to the seismic instrumentation and resulted in a locked in the Control Room alarm. At 2305, I&C technicians re-booted the computer and verified the SM system was functioning. On September 8, 2016, at approximately 2353, further review of this equipment failure and the related impact to the capability of the SM system determined that this was a reportable loss of emergency assessment capability during the period between 1856 and 2305. This specific SM functions to provide indication that the Operational Basis Earthquake threshold has been exceeded following a seismic event and is used in the PVNGS Emergency Plan to perform classification for emergency action level HA1.1, Natural or Destructive Phenomena affecting Vital Areas. As a compensatory measure, PVNGS procedures for seismic event evaluation provide alternative methods for HA1.1 event classification with the SM out of service. Maintenance to correct the condition has been completed. The NRC Resident Inspector has been informed of this condition. | ||
| ENS 51041 | 4 May 2015 10:20:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Seismic Monitoring System Out of Service | 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. This event is being reported pursuant to 10 CFR 50.72(b)(3)(xiii) for a loss of emergency assessment capability at the Palo Verde Nuclear Generating Station (PVNGS). On May 4, 2015 at 0320, seismic monitoring (SM) system force balance accelerometer R0006 was determined to be non-functional due to an emergent equipment failure. On May 4,2015, at approximately 1600, further review of this equipment failure and the related impact to the capability of the SM system determined that this was a reportable loss of emergency assessment capability. This specific accelerometer functions to provide indication that the Operational Basis Earthquake threshold has been exceeded following a seismic event and is used in the PVNGS Emergency Plan to perform classification for emergency action level HA1.1, Natural or Destructive Phenomena affecting Vital Areas. As a compensatory measure, PVNGS procedures for seismic event evaluation provide alternative methods for HA1.1 event classification with accelerometer R0006 out of service. Maintenance to correct the condition is in-progress. The NRC Resident Inspector has been informed of this condition. | ||
| ENS 49616 | 8 December 2013 15:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Assessment Due to Technical Support Center Uninterruptable Power Supply Planned Replacement | 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. At approximately 0800 Mountain Standard Time on December 8, 2013, Palo Verde Nuclear Generating Station (PVNGS) removed the Technical Support Center (TSC) uninterruptable power supply (UPS) from service for a planned replacement. The outage disables the Emergency Response Facility Data Acquisition and Display System (ERFDADS) inside the TSC, remote meteorological data display in the emergency response facilities and control rooms, and transmission of plant data to the Emergency Operations Facility (EOF) and to the NRC's Emergency Response Data System (ERDS). The outage is expected to be completed within five days. The TSC and EOF remain functional during the outage. The outage does not affect the availability of normal power to the TSC or back-up power from the TSC diesel generator. Existing telecommunication systems provided for the emergency response organization (ERO) remain functional to provide the ERO within the TSC and EOF the necessary emergency assessment capabilities, as described in the PVNGS Emergency Plan. The ERFDADS system in each of the three unit control rooms and unit satellite TSCs remain functional and are not affected by the TSC UPS outage. Compensatory measures exist within emergency plan implementing procedures to obtain meteorological tower data locally and from the National Weather Service. The ERO has been briefed on the effects of the planned TSC UPS outage. The NRC Resident Inspector has been informed. PVNGS will inform the NRC after the outage has been completed and the functionality of affected equipment has been restored.
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. This notification is an update to EN 49616 which provided notification of pre-planned maintenance activities on the Palo Verde Nuclear Generating Station (PVNGS) Technical Support Center (TSC) uninterruptable power supply (UPS) that disabled various Emergency Plan (E-Plan) data systems. At approximately 0915 Mountain Standard Time on December 12, 2013, PVNGS restored the affected data systems to service such that the functions of the E-Plan can now be performed without the use of alternate methods. The NRC Resident Inspector has been informed. Notified R4DO (Werner). | Emergency Response Data System | |
| ENS 48849 | 25 March 2013 17:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | One Alert Notification Siren Removed from Service for Planned Maintenance | 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 25, 2013, at 10:30, Mountain Standard Time, Palo Verde Nuclear Generating Station (PVNGS) removed Alert Notification System (ANS) Siren 22 from service for planned maintenance. Siren 22 provides notification to approximately 1455 members of the public within five miles of PVNGS. Siren 22 is expected to be returned to service on March 27, 2013. County authorities have been notified of this planned maintenance activity and appropriate contingency measures have been established to compensate for the non-functional siren. The PVNGS Emergency Plan contains contingencies for notification of members of the public within the affected area during an emergency when a siren is out of service. There are no events in progress that require ANS operation. The NRC Resident Inspector and the Maricopa County Sheriff's Office have been notified. | ||
| ENS 47274 | 18 September 2011 15:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Out of Service Due to Planned Maintenance | 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. This report is being made under 10 CFR 50.72(b)(3)(xiii) for unavailability of the Palo Verde Technical Support Center (TSC). On September 18, 2011, from approximately 0830 to 1700 MST, a scheduled power outage will cause the TSC to be non-functional due to the loss of lighting, ventilation, Emergency Response Facilities Data Acquisition and Display System (ERFDADS), and the Plant Information (PI) System in the TSC. Temporary lighting will be installed prior to the power outage. In the event that the TSC is required to be activated, the Emergency Response Organization (ERO) will respond to the TSC and the electrical maintenance group will stop maintenance activities and restore power. The TSC will then be declared functional after power is restored. In addition, due to the power outage to the TSC, PI and ERFDADS will be unavailable at the Emergency Operations Facility. The NRC Resident Inspector has been notified of the planned power outage. * * * UPDATE FROM MIKE KOHART TO JOHN KNOKE AT 2200 EDT ON 9/18/11 * * * At 2200 EDT the Palo Verde Technical Support Center (TSC) has been restored to service This includes Emergency Response Facilities Data Acquisition and Display System (ERFDADS), and the Plant Information (PI) System. The licensee has notified the NRC Resident Inspector. Notified the R4DO (Pick). | ||
| ENS 47268 | 14 September 2011 17:23:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Two Public Warning System Sirens | On September 12, 2011, the Palo Verde Emergency Preparedness Department discovered that public warning system siren 1 was not responding and was out of service. The loss of this siren did not constitute a loss of capability to alert a large segment of the population for greater than one hour and was therefore, not reported. Troubleshooting had commenced but was not completed. On September 14, 2011, at 1023 Mountain Standard Time, the Palo Verde Emergency Preparedness Department was notified by Maricopa County Sheriff's Office (MCSO) that siren 6 had failed. Since siren 1 remains out of service pending repairs, and siren 6 is now out of service, the loss of the two sirens constitutes a loss of capability to alert a large segment of the population for greater than one hour and is reportable. This is a reportable event as a loss of communication and assessment capability that could potentially impact a population of greater than 10 percent of the people in the 10-mile emergency planning zone (approximately 750 people affected). Therefore, this notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii). If an event occurs while the sirens are out of service, the Palo Verde Emergency Plan has a contingency for dispatching MCSO vehicles with loudspeakers to alert persons within the affected area. The MCSO is prepared to implement this contingency should it become necessary. Troubleshooting to determine the cause of the failure of siren 6 has also commenced. The NRC Resident Inspector has been notified of the out of service sirens and this ENS call. | ||
| ENS 46331 | 14 October 2010 16:15:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Emergency Sirens Will Be Taken Out of Service for Planned Maintenance | 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. From October 14, 2010 to October 22, 2010, Palo Verde personnel will be performing maintenance on public prompt notification system sirens. Sirens will be removed from service one at a time, and then each will be restored prior to continuing to the next siren. Siren #36 provides notification to approximately 470 members of the public within five miles of Palo Verde. Siren #23 provides notification to approximately 614 members of the public within five miles of Palo Verde. Siren #25 provides notification to approximately 335 members of the public within five miles of Palo Verde. Siren #18 provides notification to approximately 586 members of the public within five miles of Palo Verde. Siren #15 provides notification to approximately 1133 members of the public within five to ten miles of Palo Verde. Siren #22 provides notification to approximately 1015 members of the public within five miles of Palo Verde. Siren #17 provides notification to approximately 1196 members of the public within five miles of Palo Verde. Each of these are considered by Palo Verde to be a 'large segment of the population.' This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii). The Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area. The MCSO is prepared to implement this contingency should it become necessary. There are no events in progress that require siren operation. A follow-up call will be placed when the affected sirens are returned to service. The NRC Resident Inspector has been notified of the siren maintenance and this ENS call.
Maintenance on the Palo Verde public prompt notification sirens listed on ENS #46331 has been completed. The sirens are operable and are back in service. The NRC Resident Inspector has been notified of the siren maintenance and this ENS call. Notified R4DO (Proulx). | ||
| ENS 46188 | 18 August 2010 14:42:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Several Public Warning System Sirens | On August 18, 2010, at approximately 0742 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Department discovered that public warning system sirens Nos. 17, 23, and 34 were not responding, and therefore, were out of service. The loss of these sirens could potentially impact a population of approximately 1800 people in the 5-mile emergency planning zone (EPZ). Since the loss of these sirens could impair Arizona Public Service Company's ability to inform greater than 5% of the population within the EPZ, this notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii). If an event occurs while the sirens are out of service, the Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area. The MCSO is prepared to implement this contingency should it become necessary. Troubleshooting to determine the cause of the failure has commenced. The NRC Resident Inspector has been notified of the out of service sirens and this ENS call. (At the time of the notification to the NRC), siren #23 was restored at 1316 MST. The out of service sirens are now Nos. 17 and 34 with an affected population of 1196 within the 5 mile EPZ.
The licensee restored siren #17 at 1647 MST on 8/18/10. The restoration of this siren provided coverage to all the population within the 5-mile EPZ. The licensee has notified the NRC Resident Inspector and will also notify State and local authorities. R4DO (Miller) notified. | ||
| ENS 46140 | 30 July 2010 14:20:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Emergency Siren | On July 30, 2010, at approximately 0720 Mountain Standard Time (MST), the Palo Verde Emergency Planning Department discovered that public warning system siren No. 17 was not responding, and therefore, is out of service. The loss of siren No. 17 could potentially impact a population of approximately 1196 people in the 5-mile emergency planning zone (EPZ). Since the loss of siren No. 17 could impair Arizona Public Service Company's ability to inform greater than 5% of the population within the EPZ, this notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii). If an event occurs while siren No. 17 is out of service, the Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area. The MCSO is prepared to implement this contingency should it become necessary. Troubleshooting to determine the cause of the failure has commenced. The NRC Resident Inspector has been notified. | ||
| ENS 45968 | 1 June 2010 14:15:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Public Warning System Siren Out of Service | 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 June 01, 2010, at approximately 0715 Mountain Standard Time (MST), the Palo Verde Emergency Planning Department discovered that public warning system siren No. 17 was not responding, and therefore, is out of service. The loss of siren No. 17 could potentially impact a population of approximately 1196 people in the 5-mile Emergency Planning Zone (EPZ). Since the loss of siren No. 17 could impair Arizona Public Service Company's ability to inform greater than 5% of the population within the EPZ, this notification is being made in accordance with 10 CFR 10.72(b)(3)(xiii). If an event occurs while siren No. 17 is out of service, the Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area. The MCSO is prepared to implement this contingency should it become necessary. The NRC Resident Inspector has been notified of siren No. 17 being out of service and this ENS call.
Siren number 17 was returned to service at 1435 MST. The NRC Senior Resident Inspector has been notified. The remote radio was replaced and all post-maintenance testing was completed. Notified R4DO (Werner). | ||
| ENS 45425 | 11 October 2009 11:50:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Reactor Water Level Indication Inoperable | 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 (Emergency Notification System) or under the reporting requirements of 10CFR50.73. On 10/11/2009 at 0450 MST Palo Verde Nuclear Station Unit 1 declared both trains of the Qualified Safety Parameter Display (QSPDS) inoperable due to the discovery that an installed temporary modification (TMOD) impacted the reactor vessel level indication parameter in a non-conservative manner. The modification jumpered failed heater junction thermal connections (HJTC) at the heated and unheated HJTC points. Unit 1 has two failed detectors with TMODs installed. During a design event where these detectors would be needed, these detectors will not alarm at the correct vessel levels. The emergency operating procedures use this indication and pressurizer level indications (which are unaffected by this condition) to throttle safety injection flow during certain accidents. With the TMOD providing incorrect indication the operators could throttle flow when full flow should be maintained. In addition the QSPDS reactor level indication is used in the Emergency Plan to classify emergencies. The standard Appendix 101 to Palo Verde emergency procedures provides guidance for an alternate method for determining reactor vessel level when RVLMS (Reactor Vessel Level Monitoring System) is out of service. This alternate method determines level by manually determining sub-cooled, saturation or superheated conditions based upon input of reactor vessel pressure and the "raw" QSPDS - RVLMS thermocouple temperature indications. This compensatory measure ensures that classification of events can continue to be completed in a timely manner. Unit 1 has entered the LCO (Limiting Condition of Operation) required action for this condition which requires at least one channel be restored to operable status within 7 days. Unit 2 is in a refueling and is not impacted at this time. Unit 3 does not have the TMOD installed. According to the licensee Train A TMOD which was installed 2/3/08 and the train B TMOD which was installed 12/12/08. The licensee checked the installation of these TMODs after reviewing operating experience reports from Calvert Cliffs. The licensee has notified the NRC Resident Inspector.
On 10/11/2009 at 12:26 MST Palo Verde Nuclear Station Unit 1 reported the inoperability of both trains of the Qualified Safety Parameter Display System (QSPDS) due to the discovery that an installed temporary modification impacted the reactor vessel water level indication parameter in a non-conservative manner. After further Operations and Engineering review it was concluded that the modification, installed due to one inoperable heated junction thermal couple (HJTC) in each train, does not result in the inoperability of either train of QSPDS since the Technical Specification required number of heated junction thermal couples (HJTC) (two each in the upper and lower level indication) remain operable with the temporary modification installed. In addition, the Control Room operators would understand the QSPDS indication and would correctly control the plant per the emergency operating procedures using this indication along with pressurizer level indication to throttle safety injection flow during certain accidents. The QSPDS reactor level indication is also used in the Emergency Plan to classify emergencies and the modification would not impact this function. Unit 1 has exited the LCO Condition for two inoperable QSPDS reactor vessel water level instrument channels. The licensee has notified the NRC Resident Inspector. R4DO (Okeefe) notified. | Qualified Safety Parameter Display System | |
| ENS 44924 | 21 March 2009 16:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Various Control Room Annunciators and Alarms Out of Service Due to Maintenance on Power Supply | 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 21, 2009, from approximately 09:00 Mountain Standard Time (MST) until 14:00 MST, Palo Verde maintenance personnel will be performing scheduled maintenance to repair one of two redundant 120 VAC power supplies in Unit 2 that provides power to various alarms in the main control room. This work will require both power supplies to be de-energized resulting in approximately 50 percent of the Unit 2 plant annunciators being unavailable. The following compensatory measures will be in place for the duration of the scheduled work: Other assessment indications will remain available:
Plant Monitoring System
Qualified Safety Parameter Display System
Emergency Response Facility Data Acquisition System
No changes in plant power or operating mode are planned.
A third licensed operator will be in the control room.
The NRC Resident Inspector has been notified of the scheduled outage and this ENS call.
The power supply was successfully repaired and all annunciators were restored to normal as of 1515 MST. The Licensee will notify the NRC Resident Inspector. Notified R4DO (Hay) and NRR EO (Holian). | Qualified Safety Parameter Display System | |
| ENS 44692 | 2 December 2008 23:20:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of One (1) Emergency Siren | 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 December 2, 2008, at approximately 1620 Mountain Standard Time (MST), the Palo Verde Emergency Planning Department discovered that public warning system siren No. 17 was not responding, and therefore, is out of service. The loss of siren No. 17 could potentially impact a population of approximately 1106 people in the 5-mile emergency planning zone (EPZ). Since the loss of siren No. 17 could impair Arizona Public Service Company's ability to inform greater than 5% of the population within the EPZ, this notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii). If an event occurs while siren No. 17 is out of service, the Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area. The MCSO is prepared to implement this contingency should it become necessary. Troubleshooting to determine the cause of the failure will start tomorrow morning (December 3, 2008). The NRC Resident Inspector has been notified of siren No. 17 being out of service and this ENS call.
Siren 17 was returned to service on Wednesday, December 3, 2008, at 0829 MST. Notified R4DO (Proulx). | ||
| ENS 44606 | 28 October 2008 16:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Maintenance on Public Prompt Notification System Emergency Sirens | The following event description is based on information currently available. If through subsequent reviews of the event, additional information is identified that is pertinent to this event or alters the information being provided at the time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. From October 28, 2008 until October 31, 2008, Palo Verde personnel will be performing maintenance on public prompt notification system sirens. One siren at a time will be removed from service, and will be restored prior to continuing to the next siren. Siren #42 provides notification to approximately 558 members of the public within 5 miles of Palo Verde. Siren #44 provides notification to approximately 210 members of the public within 5 miles of Palo Verde. Siren #25 provides notification to approximately 302 members of the public within 5 miles of Palo Verde. Siren #23 provides notification to approximately 498 members of the public within 5 miles of Palo Verde. Siren #22 provides notification to approximately 855 members of the public within 5 miles of Palo Verde. Siren #18 provides notification to approximately 396 members of the public within 5 miles of Palo Verde Siren #17 provides notification to approximately 1106 members of the public within 5 miles of Palo Verde. Siren #36 provides notification to approximately 301 members of the public within 5 miles of Palo Verde. Siren #15 provides notification to approximately 940 members of the public within 5 to 10 miles of Palo Verde. Each of these are considered by Palo Verde to be a 'large segment of the population.' The Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles, during an actual event, with loud speakers to alert persons within the affected area when sirens are inoperable. There are no events in progress that require siren operation. A follow-up call will be placed when the affected sirens are returned to service. The NRC Resident Inspector has been notified of the siren maintenance and this ENS call. These sirens are utility owned.
The following information was received as an update to this report: This is an update of ENS call # 44606. At this time, maintenance on the Palo Verde public prompt notification for sirens identified in ENS #44606, has been completed, siren testing was successful and the sirens are operable and in service at this time. The NRC Resident Inspector has been notified of the siren maintenance and this ENS call. Notified R4DO (Spitzberg). | ||
| ENS 43824 | 4 December 2007 14:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness 10 CFR 50.72(b)(3)(xii), Transport of a Contaminated Person Offsite | Offsite Notification Due to Potential Loss of Three Sirens | 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 December 04, 2007 at approximately 07:00 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Department discovered sirens 17, 18 and 23 out of service. Siren #23 was restored to service at 09:34 and siren 18 was restored to service at 10:32. Siren 17 remains out of service and is estimated to impact approximately 206 members of population in the emergency planning zone (EPZ) within 5 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles. This call is being placed due to the relatively large segment of the population affected (10 CFR 50.72(b)(3)(xiii)). During an event, the Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected areas when sirens are inoperable. In order to activate this contingency, Maricopa County Department of Emergency Management was notified of the failed siren at 12:58 (10 CFR 50.72(b)(2)(xi)). There are no events in progress that require siren operation. The NRC Resident Inspector has been notified of the siren 17 being out of service and this ENS call. The utility received a pulse check report at 0700 this morning which indicated that three sirens failed the initial pulse check. After the second pulse check, two of the three sirens responded correctly. However, the third siren (No. 17) remained OSS, and the licensee has dispatched a crew to repair it. | ||
| ENS 42701 | 12 July 2006 14:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | One Siren in Ep Zone Is Out of Service | 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 July 12, 2006 at approximately 07:30 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Department reported siren (#23) out of service. Siren #23 is estimated to impact approximately 119 members of population in the emergency planning zone (EPZ) within 5 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles. This call is being placed due to the relatively large segment of the population affected. During an event, the Palo Verde Emergency Plan has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. There are no events in progress that require siren operation. The NRC Resident Inspector has been notified of the siren 23 being out of service and this ENS call. The total population within the 5 mile EPZ is 2120. | ||
| ENS 41941 | 23 August 2005 20:49:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Two Emergency Sirens Inoperable | 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 August 23, 2005 at approximately 13:49 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Department identified a siren (#42) inoperable due to a failed battery charger. At approximately 14:00 a faxed notice was found indicating siren #15 had failed its response check. The fax was sent approximately at 07:00 but was not noticed till later since out of service siren notifications are generally made via phone or e-mail. Upon investigation, siren #15 was found inoperable due to a circuit board failure. Siren #15 is estimated to impact approximately 144 members of population in the emergency planning zone (EPZ) within 5 miles, and siren #42 is estimated to impact 496 members of the population in the EPZ, beyond 5 miles but within 10 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles and 10% of the population beyond 5 miles but within 10 miles. This call is being placed due to the relatively large segment of the population affected and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. There are no events in progress that require siren operation. The NRC Resident Inspector has been notified of the siren failure and this ENS call. | ||
| ENS 41912 | 11 August 2005 15:45:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | One Emergency Preparedness Siren Out of Service | On August 11, 2005 at approximately 08:45 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Department identified an inoperable single siren (#15). While reviewing the siren monitoring computer log, an Information Services Technician received a 'no response' signal on siren #15. Upon investigation, siren #15 was found inoperable. The siren was vandalized by destroying the siren controller case and stealing the internal battery. The affected siren is estimated to impact approximately 496 members of population in the emergency planning zone (EPZ) beyond 5 miles but within 10 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 10% of the population beyond 5 miles but within 10 miles. This call is being placed due to the relatively large segment of the population affected and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. The County was informed at 09:05 MST to implement the MCSO notification if a need arises. There are no events in progress that require siren operation. The licensee notified the NRC Resident Inspector. | ||
| ENS 41874 | 26 July 2005 23:35:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Inoperable Single Emergency Siren | On July 26, 2005 at approximately 09:07 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Department was notified of an inoperable single siren (#42). While reviewing the siren monitoring computer log, an Information Services Technician received a no response signal on siren #42. Upon investigation, siren #42 was found inoperable. The siren was vandalized by destroying the battery case and stealing the internal battery. The affected siren is estimated to impact approximately 144 members of population (6.8%) in the emergency planning zone (EPZ) within 5 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles (or 10% within 5 to 10 miles) for greater than 1 hour. This call is being placed due to the relatively large segment of the population affected and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. The County was informed at 09:38 MST to implement the MCSO notification if a need arises. There are no events in progress that require siren operation. The NRC Resident Inspector has been notified of the siren failure and this ENS call. | ||
| ENS 41810 | 29 June 2005 11:43:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Evacuation Siren Inoperable | 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 June 29, 2005 at approximately 08:55 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Program Manager was notified of an inoperable single siren #36. An alarm indicates that the inoperability started at 04:43 AM MST. The siren was vandalized by destroying the battery case and stealing the internal battery. The affected siren is estimated to impact approximately 215 members of population (10.1 %) in the emergency planning zone (EPZ) within 5 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles (or 10% within 5 to 10 miles) for greater than 1 hour. This call is being placed due to the relatively large segment of the population affected and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriffs Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. The County was informed at 09:25 AM MST to implement the MCSO notification if a need arises. There are no events in progress that require siren operation. The NRC Resident Inspector has been notified of the siren failure and this ENS call. | ||
| ENS 41486 | 13 March 2005 01:45:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Operability of One Emergency Evacuation Siren | The following was provided by the licensee: 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 12, 2005 at approximately 18:45 Mountain Standard Time, the Palo Verde Emergency Preparedness Program Manager was notified of an inoperable single siren #36. Palo Verde has had 4 other sirens vandalized by breaking locks and stealing the internal battery since approximately February 25, 2005. The specific cause of this siren being inoperable has not been determined. Based on evidence from previous testing, this loss of siren #36 has been established to have occurred sometime between 22:00, Friday, 03/11/2005 and 03:00, Saturday, 03/12/2005. The affected siren is estimated to impact approximately 82 members of population (5.1 %) in the emergency planning zone (EPZ) within 5 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles (or 10% within 5 to 10 miles) for greater than 1 hour. This call is being placed due to the relatively large segment of the population affected and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. Palo Verde has also been informed that Siren #42, previously inoperable due to the same vandalism and reported in EN #41451 on February 28, 2005, has been returned to service. There are no events in progress that require siren operation. There was not anything unusual or not understood concerning this event and all systems functioned as required. The NRC Resident Inspector has been notified of the siren failure and this ENS call. The licensee will inspect the siren on Sunday or Monday to determine if vandalism is involved. | ||
| ENS 41466 | 7 March 2005 15:10:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Two Emergency Sirens Inoperable | The following information was received from the licensee via facsimile (licensee text in quotes): 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, 2005 at approximately 08:10 Mountain Standard Time, the Palo Verde Emergency Preparedness Program Manager was notified of vandalism to two sirens, #18 and #23, that resulted in the sirens being inoperable. The affected sirens are estimated to impact approximately 465 (total) members of population (approximately 29%) in the emergency planning zone (EPZ) within 5 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles (or 10% within 5 to 10 miles) for greater than 1 hour. This call is being placed due to the relatively large segment of the population affected, and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. There are no events in progress that require siren operation. The NRC Resident Inspector has been notified of the siren failure and this ENS call. The vandals cut the battery cables and removed the batteries. The theft has been reported to the MCSO. | ||
| ENS 41451 | 28 February 2005 21:57:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Major Loss of Siren Coverage within the Emergency Planning Zone | The following information was provided by the licensee via facsimile (licensee text in quotes): 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 February 28, 2005 at approximately 14:57 Mountain Standard Time, the Palo Verde Emergency Preparedness Program Manager was notified of vandalism to a single siren (#42) that resulted in the siren being inoperable. Based on evidence from previous testing, the vandalism has been established to have occurred sometime between 15:00, Friday, 02/25/2005 and 03:00, Saturday, 02/26/2005. The affected siren is estimated to impact approximately 116 members of the population (7.3%) in the emergency planning zone (EPZ) within 5 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 5% of the population within 5 miles (or 10% within 5 to 10 miles) for greater than 1 hour. This call is being placed due to the relatively large segment of the population affected, and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable. There are no events in progress that require siren operation. The NRC Resident Inspector has been notified of the siren failure and this ENS call. |