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 Entered dateSiteRegionReactor typeEvent description
ENS 539681 April 2019 06:40:00Palo VerdeNRC Region 4At 2006 (MST), on 3/31/2019, the Palo Verde Nuclear Generating Station Unit 1 Shift Manager was informed that leakage was measured from the Train A Emergency Core Cooling System (ECCS) piping at approximately 100 ml/minute through a High Pressure Safety Injection (HPSI) A drain valve. This value exceeds the assumed 3000 ml/hour ECCS leakage for a large break loss of coolant accident analysis. At 0230 (MST) on April 1, 2019, the valve was flushed and the leakage reduced to 10 ml/minute (600 ml/hour) and was no longer above the limit of the safety analysis. This condition is being reported as an unanalyzed condition per 10 CFR 50.72(b)3)(ii)(B) and a condition that could have prevented the fulfillment of a safety function to the control the release of radioactive material per 10 CFR 50.72(b)(3)(v)(C). This event did not result in an abnormal release of radioactive material. Notification received by Caty Nolan and emailed to HOO.HOC@NRC.GOV The NRC asked a followup question: Why was the criterion for Control of Radioactive Material selected? per the PVNGS Unit 1 Shift Manager, this criterion was selected due to the potential of exceeding offsite dose projections, post recirculation, following a Design Basis Accident. The resident inspector has been notified.
ENS 5370229 October 2018 12:56:00Palo VerdeNRC Region 4The 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 03:30 MST on October 29, 2018, an Arizona Public Service Company (APS) employee developed a personal medical condition in the Owner Controlled Area outside of the Secured Owner Controlled Area at Palo Verde Generation Station (PVGS). PVGS Emergency Medical Technicians responded and transported the individual to an offsite emergency trauma center. Upon arrival at the trauma center, medical personnel declared the individual deceased at approximately 05:35 MST. The fatality was not work related and the individual was outside of the Radiological Controlled Area and no radioactive material or contamination was involved. No news release by APS is planned. Notifications were made to the Arizona Division of Occupational Safety and Health at 08:15 MST. The NRC Resident Inspectors have been notified."
ENS 5357531 August 2018 16:04:00Palo VerdeNRC Region 4The 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."
ENS 5352224 July 2018 00:57:00Palo VerdeNRC Region 4The 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."
ENS 5347728 June 2018 05:37:00Palo VerdeNRC Region 4The 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 10 CFR 50.73. On June 27th, 2018 at approximately 2310 Mountain Standard Time (MST), in Palo Verde Unit 3, the #1 Steam Generator Economizer valve started closing. This caused Steam Generator #1 water level to decrease. Both Feed water pumps speed increased to raise Steam Generator level. At approximately 2311 (MST), the B Main Feed water pump tripped resulting in a Reactor Power Cutback. Steam Generator #1 level continued to decrease resulting in an Automatic Reactor Trip on Low Steam Generator #1 water level. All control rods inserted to shut down the Reactor to Mode 3 using Main Feed water and Steam Bypass. Post trip Steam Generator #1 level then increased and at approximately 2316 (MST) a Main Steam Isolation Signal (MSIS) was received on high Steam Generator level. The 'B' Auxiliary Feed water pump was manually started to maintain Steam Generator water levels and Steam Generator pressure was controlled using the Atmospheric Dump Valves (ADVs). Following the reactor trip, all CEAs (Control Element Assemblies) inserted fully into the core. All systems operated as expected. No emergency plan classification was required per the Emergency Plan. Safety related busses remained powered during the event from offsite power and the offsite power grid is stable. No major equipment was inoperable prior to the event that contributed to the event or complicated operator response. Unit 3 is stable and in Mode 3 feeding Steam Generators with Auxiliary Feed water Pump 'B'. 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 was informed of the Unit 3 reactor trip. Unit 1and Unit 2 were unaffected by the Unit 3 trip.
ENS 5342423 May 2018 17:37:00Palo VerdeNRC Region 4CE

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 May 23, 2018, at approximately 1128 Mountain Standard Time (MST), the Palo Verde Nuclear Generating Station (PVNGS) Unit 2 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 2 was operating normally at 100 percent power. Plant operators entered the reactor trip procedures and diagnosed an uncomplicated reactor trip. All CEAs (control element assemblies) fully inserted into the core. No emergency classification was required per the PVNGS Emergency Plan. The Unit 2 safety-related electrical buses remained energized from normal offsite power during the event. There was no impact to the required circuits between the offsite transmission network and the onsite Class 1E Electrical Power Distribution System; the offsite power grid is stable. No major equipment was inoperable prior to the event that contributed to the event or complicated operator response. Unit 2 is currently stable in Mode 3 with the reactor coolant system at normal operating temperature and pressure. The cause of the reactor trip is under investigation. 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 2 reactor trip. Decay is being removed via steam dumps to condenser. Units 1 and 3 at Palo Verde were unaffected by the transient and continue to operate at 100 percent power.

ENS 5321516 February 2018 02:50:00Palo VerdeNRC Region 4CE

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.

  • * * UPDATE ON 2/16/18 AT 1640 EST FROM DAVID HECKMAN TO DONG PARK * * *

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).

  • * * UPDATE AT 1537 EDT ON 03/30/18 FROM LORRAINE WEAVER TO JEFF HERRERA * * *

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).

ENS 5301514 October 2017 16:37:00Palo VerdeNRC Region 4CEAt approximately 19:48 Mountain Standard Time on October 13, 2017, Palo Verde Nuclear Generating Station (PVNGS) staff confirmed a non-licensed supervisor tested positive for drugs during a random 'Fitness for Duty' test. The person's access authorization was terminated in accordance with station procedures. The NRC resident inspector has been notified by the licensee.
ENS 5301012 October 2017 20:26:00Palo VerdeNRC Region 4CEA contract employee supervisor had a confirmed positive for illegal drugs during an initial screening test. The individual's access to the plant has been terminated. The NRC Resident Inspector has been notified by the Licensee.
ENS 5298922 September 2017 20:08:00Palo VerdeNRC Region 4CEThe 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 526707 April 2017 14:49:00Palo VerdeNRC Region 4CEOn April 5, 2017, Arizona Public Service Company (APS) completed an evaluation of a deviation, and concluded the condition represented a defect under 10 CFR 21. APS previously submitted an interim report (ADAMS Accession Number ML 16344A118) for this condition pursuant to 10 CFR 21.21(a)(2). A GE-Hitachi Type AKR-2BE-50, 2000 Amp circuit breaker (used to connect Class 1E batteries to the related Class 1E 125 VDC busses) exhibited arcing and smoking during current injection testing performed to test the overcurrent trip setpoint prior to installation. Arcing occurred at one of two hex bolts anchoring the protective trip device to the line side bus. The electrical arcing resulted from inadequate tightening of both hex bolts which caused a loose electrical connection on the bus within the breaker. APS concluded this condition could result in the breaker failing to perform its safety function and thus could create a substantial safety hazard. The breaker had been refurbished by GE-Hitachi and was received by APS and tested on October 13, 2016. Following the test failure, the damaged bolt was replaced, both bolts were tightened, and the breaker was retested and installed. Pre-installation inspection and testing that includes current injection testing, recommended in GEH document GEK-64459, should, and did, detect faults such as the condition identified in this notification. GE-Hitachi entered this failure into their corrective action program. Vendor: GE HITACHI NUCLEAR ENERGY, 3901 CASTLE HAYNE RD., WILMINGTON, NC 28402-2819 Device: Breaker Model AKR-2BE-50, 2000 Amp, Serial No. N8682600001 The NRC Resident Inspector has been informed.
ENS 5243515 December 2016 06:55:00Palo VerdeNRC Region 4CE

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).

  • * * UPDATE AT 0947 EST ON 12/15/2016 FROM MICHAEL GOODRICH TO MARK ABRAMOVITZ * * *

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).

ENS 524137 December 2016 16:59:00Palo VerdeNRC Region 4CEThe 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 telephone notification is being made pursuant to the reporting requirements of 10 CFR 50.73(a)(2)(iv)(A) and 50.73(a)(1) to describe an invalid actuation of the Palo Verde Nuclear Generating Station (PVNGS) Unit 1 train A emergency diesel generator (EDG), train A high pressure safety injection (HPSI) pump, and train A essential spray pond (SP) pump. These components are portions of the emergency ac electrical power system, the emergency core cooling system, and the emergency service water system, respectively, as described in 10 CFR 50.73(a)(2)(iv)(B). On October 17, 2016 at approximately 1519, Mountain Standard Time, a portion of the Unit 1 train A engineered safety features equipment was automatically started by the balance-of-plant (BOP) engineered safety features actuation system (ESFAS) while the plant was at steady state conditions. Initiation of the train A ESFAS actuation signal was momentary, and the ESFAS actuation signal cleared 0.2 seconds after being initiated. The invalid ESFAS signal initiated a test-mode start signal for the train A EDG and started the train A HPSI pump. The train A essential SP pump started in support of the train A EDG. All actuated components started and functioned successfully. No systems started in response to actual plant conditions, and no actuation was required to mitigate the consequences of an event. The invalid HPSI actuation neither resulted in an emergency core cooling system discharge, nor should it have. The invalid actuation was the consequence of a spurious momentary signal into the BOP-ESFAS control panel due to an intermittent high resistance electrical connection. The event was entered into the PVNGS corrective action program. There were no adverse impacts to public health and safety nor to plant employees. The NRC Resident Inspectors have been informed.
ENS 5230920 October 2016 00:09:00Palo VerdeNRC Region 4CE

While performing a scheduled inservice inspection on a section of safety injection system piping, a flaw was identified in a circumferential weld on the 14 inch safety injection line from the 2A safety injection tank to the 2A reactor coolant loop. Examination results indicate that the flaw constitutes a welding defect that cannot be found acceptable under ASME Section XI, IWB-3600, or Table IWB-3410-1. Further analysis is being conducted. The unit had been shutdown for its 19th refueling outage (3R19) on October 8, 2016, at 0000. The NRC Resident Inspectors have been informed of this condition. This piping is required to be operable in modes one through four.

  • * * RETRACTION ON 11/10/16 AT 1640 EST FROM ROBERT CHU TO MARK ABRAMOVITZ * * *

Subsequent engineering examination of the weld on the 14" safety injection line from the 2A safety injection tank to the 2A reactor coolant loop using enhanced examination techniques concluded the indication in the circumferential weld does not represent a flaw constituting a weld defect. The indication was the result of a metallurgical weld interface in the area of a previously documented weld repair. Therefore, the indication is acceptable under ASME Section XI with no further analysis required. Based on the above information, PVNGS has determined the indication does not represent a degraded condition of a principal safety barrier as defined by 10CFR 50.72(b)(3)(ii)(A) and event notification #52309 is retracted. The NRC Resident Inspectors have been notified. Notified R4DO (Campbell).

ENS 522299 September 2016 03:59:00Palo VerdeNRC Region 4CEThe 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 522288 September 2016 16:12:00Palo VerdeNRC Region 4CEThe 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 telephone notification is being made pursuant to the reporting requirements of 10CFR50.73(a)(2)(iv)(A) and 50.73(a)(1) to describe an invalid actuation of both trains of the Palo Verde Nuclear Generating Station (PVNGS) Unit 2 essential spray pond (SP) system. The SP system serves as an emergency service water system that does not normally run and serves as an ultimate heat sink as described in 10CFR50.73(a)(2)(iv)(B)(9). On July 12, 2016, at approximately 0550, Mountain Standard Time, Unit 2 experienced a manual actuation of both trains of the SP system. Approximately 20 minutes earlier, the failure of a +15VDC power supply on the containment purge isolation actuation signal (CPIAS) module resulted in a trip of the B train CPIAS and a momentary cross trip of the A train CPIAS, and both trains of the control room essential filtration actuation system (CREFAS). These brief actuation signals resulted in starting of some but not all essential equipment because the actuation signals cleared before most of the equipment received a start signal. Both trains of the SP system were started manually in accordance with the alarm response procedure. The A train CPIAS and both trains of CREFAS were reset. The B train CPIAS remained in a partially tripped state because of the failed power supply. The manual actuation of both A and B trains of the SP system was complete. Both trains of the SP system started and functioned successfully. The invalid actuation was the consequence of a failed +15VDC power supply on the B train CPIAS module which resulted in momentary trips of both trains of CPIAS and CREFAS. The containment building radiation monitors that actuate CPIAS exhibited normal radiation levels which would not have required CPIAS actuation. The event was entered into the PVNGS corrective action program. There was no adverse impact to public health and safety nor to plant employees. The NRC Resident Inspectors have been informed.
ENS 522268 September 2016 04:27:00Palo VerdeNRC Region 4CEOn September 7th, 2016 at approximately 2131 Mountain Standard Time (MST), Palo Verde Unit 1 was manually tripped due to a stuck open main spray valve. Unit 1 was operating at 100 percent power at normal operating temperature and pressure prior to the event. A 120 VAC non-class instrument distribution panel was being transferred to its alternate power supply to establish maintenance conditions. The distribution panel failed to transfer. The panel remained energized from its normal power supply; however, multiple components powered from the distribution panel began to exhibit uncharacteristic behavior. At this time, it was noted that a reactor coolant system main spray valve was open. The alarm response procedure was followed; however, the actions taken were unsuccessful at closing the main spray valve. The plant was then manually tripped due to pressurizer pressure continuing to lower. The reactor coolant pumps were turned off to terminate main pressurizer spray flow to control pressurizer pressure due to the inability to close the main spray valve. No ESF (Engineered Safety Features) actuations occurred and none were required. No emergency classification was required per the emergency plan. Safety related buses remained energized during and following the reactor trip. The emergency diesel generators did not start and were not required. The offsite power grid is stable. Limiting condition for operation 3.4.1 was entered due to low pressurizer pressure. No major equipment was inoperable prior to the event that contributed to the event. Unit 1 is stable at normal operating temperature and pressure in Mode 3. Reactor coolant pumps are secured and natural circulation has been verified. Primary pressure is being maintained at its normal operating pressure manually with pressurizer heaters and auxiliary spray, from the charging system. 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 minimum RCS pressure was approximately 2070 psia (normal 2250). The event did not adversely affect the safe operation of the plant or the health and safety of the public. All rods inserted and the trip was uncomplicated. Units 2 and 3 were not affected and continue to run at full power. The NRC Resident Inspector has been notified.
ENS 5220930 August 2016 18:07:00Palo VerdeNRC Region 4CEA non-licensed employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been suspended.
ENS 5208312 July 2016 21:53:00Palo VerdeNRC Region 4CE

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 the performance of a fire seal and barrier surveillance test, a degraded fire seal barrier that provides 1 hour separation between two fire zones containing redundant safe shutdown trains was identified in the 100 foot elevation of the PVNGS Unit 1 Auxiliary Building. This condition is reportable in accordance with 10CFR50.72(b)(3)(ii)(B) as an unanalyzed condition. Fire protection detection and mitigation systems in both fire zones are operable and compensatory measures (fire watches) have been implemented for affected areas. The NRC Resident Inspector has been notified. The degraded fire barrier consists of two holes in the through wall fire barrier surrounding two two-inch conduits. The two holes are approximately one to one and a half inches across.

  • * * RETRACTION FROM SEAN DORNSEIF TO HOWIE CROUCH AT 1356 EDT ON 8/18/16 * * *

Subsequent Engineering evaluation concluded the degraded fire seal in PVNGS Unit 1 reported on July 12, 2016, did not place PVNGS in an unanalyzed condition that significantly degraded plant safety. The degraded fire seal would have continued to provide the required degree of separation for redundant safe shutdown trains. The evaluation found a fire initiated in a fire zone on either side of the barrier would not propagate within one hour into the adjacent zone with redundant safe shutdown equipment. These conclusions were based on an existing fire analysis which was used to demonstrate that the required degree of separation between safe shutdown equipment remained intact. Based on the above information, PVNGS is retracting event notification report #52083, as the degraded fire seal did not place PVNGS Unit 1 an unanalyzed condition that significantly degraded plant safety. The NRC Resident Inspectors have been informed. Notified R4DO (Proulx).

ENS 519105 May 2016 15:39:00Palo VerdeNRC Region 4CE

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. At 0500 MST on May 5, 2016, engineering personnel determined that leakage from the bonnet seal weld of the Train B High Pressure Safety Injection (HPSI) system loop 2A injection valve, SIBUV0616, constituted reactor coolant system pressure boundary leakage. This is being reported as a degradation of a principal safety barrier pursuant to 10 CFR 50.72(b)(3)(ii)(A). The leak was identified during a planned activity in which Operations was filling the refueling pool using HPSI pump B. Leakage was stopped when a plant operator closed SIBUV0616. PVNGS Unit 1 was shut down for its 19th refueling outage (1R19) on April 9, 2016, at 0000 MST and is in Mode 6. The NRC Resident Inspectors have been informed of this condition.

  • * * RETRACTION PROVIDED BY JORGE RODRIGUEZ TO JEFF ROTTON AT 1732 EDT ON 06/29/2016 * * *

Subsequent engineering evaluation of the leak condition concluded the leakage from the bonnet seal weld of SIBUV0616 was not reportable reactor coolant system pressure boundary leakage. This conclusion was based on further reviews of the PVNGS licensing bases, ASME Code requirements, and design features of the valve with vendor assistance, which determined that the body-to-bonnet threads provide the structural support for the mechanical joint and the seal weld is not required for structural integrity of the component. Based on the above information, PVNGS has determined the leakage did not represent a degraded condition of a principal safety barrier as defined by 10 CFR 50.72(b)(3)(ii)(A) and Event Notification No. 51910 is hereby withdrawn. The NRC Resident Inspectors have been informed. Notified R4DO (Werner)

ENS 5186111 April 2016 15:37:00Palo VerdeNRC Region 4CEThe 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 2335 (MST) on April 10, 2016, while performing planned routine visual examinations of Unit 1 components in the Containment Building, engineering personnel identified white residue on the piping instrument nozzle for the reactor coolant system (RCS) 2B cold leg resistance temperature detector, 1JRCET121Y. The white residue was dry and no active leakage was noted on the instrument nozzle. Preliminary chemical analysis for radionuclide and boron content of the white residue determined the existence of boron and the isotopic content was consistent with RCS fluid. At 0535 (MST) on April 11, 2016, it was determined the residue resulted from RCS pressure boundary leakage, based on results of the chemical analysis and additional examination of the piping and instrument nozzle by qualified engineering personnel. Technical Specifications Limiting Condition of Operation (LCO) 3.4.14 permits no RCS pressure boundary leakage and therefore, the discovery of leakage from the instrument nozzle represents a degradation of a principal safety barrier. This notification is being made for a degraded condition pursuant to the requirements of 10CFR 50.72(b)(3)(ii)(A). The unit has been shut down for its 19th refueling outage since 4/9/16 at 0000. The NRC resident inspectors have been informed of this condition.
ENS 518442 April 2016 03:50:00Palo VerdeNRC Region 4CEThe 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 2229 (MST) on April 1, 2016, Arizona Public Service Company completed an offsite notification to the Environmental Protection Agency's National Response Center to report a spill of approximately 8000 gallons of sodium hypochlorite (8% solution) in the vicinity of the Unit 3 cooling towers at the Palo Verde Nuclear Generating Station (PVNGS). Additional notifications were made to Arizona State and Maricopa County environmental authorities. The Unit 3 cooling towers are located in the Security Owner Controlled Area at PVNGS and are outside of the protected area. The leak, which resulted from a failed hose on the main hypochlorite distribution header, was stopped by closing a valve to isolate the header. The immediate area has been barricaded. The quantity released exceeded the Reportable Quantity for sodium hypochlorite (RQ of 100 pounds) and was therefore reported. There was no impact to the operation of the PVNGS units or personnel onsite or offsite. The NRC Senior Resident has been notified.
ENS 515229 November 2015 08:40:00Palo VerdeNRC Region 4CE

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.

  • * * UPDATE FROM ROB WARNER TO DONALD NORWOOD AT 1125 EST ON 11/9/2015 * * *

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.

ENS 5140317 September 2015 02:53:00Palo VerdeNRC Region 4CE

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.

  • * * UPDATE FROM ROBERT PIERCE TO HOWIE CROUCH AT 0702 EDT ON 9/17/15 * * *

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 510415 May 2015 00:48:00Palo VerdeNRC Region 4CEThe 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 5099720 April 2015 17:57:00Palo VerdeNRC Region 4CEThe licensee discovered evidence of prohibited material inside the protected area. The material has been removed. The licensee has notified the NRC Resident Inspector.
ENS 5098415 April 2015 02:07:00Palo VerdeNRC Region 4CEThe 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. Arizona Public Service Co. made an offsite notification to the National Response Center regarding an approximately 3500 gallon caustic (8% sodium hydroxide) spill due to an improper valve lineup. The spill occurred at the Water Reclamation Facility (produces water for cooling towers and power plant and is located outside the Security Owner Controlled Area) in the area of the Fire Protection tanks (additional liquid was contained in a containment structure at the release location, and in a nearby concrete lined storm ditch on site). The release has been isolated, the immediate area has been barricaded. The quantity released exceeded the Reportable Quantity for sodium hydroxide (RQ of 1,000 pounds) and was therefore reported. Additionally, the state (Arizona) and county (Maricopa) have also been notified. There was no impact to the operation of the power units, aquifer or personnel onsite or offsite. The NRC Resident (Inspector) has been notified.
ENS 509688 April 2015 11:40:00Palo VerdeNRC Region 4CEThe 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. At approximately 0030 (MST) on April 7, 2015, while performing planned routine visual examinations of Unit 3 components, the differential pressure instrumentation nozzle on the suction side of the 2A reactor coolant pump (RCP) was observed to have white deposits that appeared to originate at the nozzle penetration. At this time, no additional indications of leakage have been identified for other inspected reactor coolant pressure boundary nozzles. Following insulation removal, the piping was examined by qualified engineering personnel. At 0330 (MST) on April 8, 2015, it was determined, based on isotopic analysis, that the white residue is consistent with reactor coolant system fluid. Technical Specifications Limiting Condition of Operation (LCO) 3.4.14 permits no reactor coolant system pressure boundary leakage and therefore, the discovery of leakage from the nozzle is a degradation of a principal safety barrier. This notification is being made for a degraded condition pursuant to the requirements of 10 CFR 50.72(b)(3)(ii)(A). The unit had been shutdown for its 18th refueling outage on 4/3/15 at 0000 (MST). The NRC Resident Inspectors have been informed of this condition.
ENS 506006 November 2014 18:22:00Palo VerdeNRC Region 4CE

On November 6, 2014 at 1116 Mountain Standard Time (MST), Control Element Assembly (CEA) 15 dropped fully into the core while all other CEAs remained fully withdrawn. Limiting Condition for Operation (LCO) 3.1.5 Condition A was entered for one CEA misaligned from its group which requires restoration of the CEA within 2 hours. An initial power reduction was performed upon receipt of the deviation in accordance with technical specifications. The CEA could not be aligned within 2 hours and LCO 3.1.5 Condition C was entered at 1316 MST which requires entry into Mode 3 within 6 hours. Power reduction continues as necessary to comply with technical specifications. No major equipment was inoperable prior to the event that contributed to the event. No emergency classification was required per the Emergency Plan. No automatic essential safety feature actuations occurred and none were required. The Emergency Diesel Generators did not start and were not required. Safety related buses remain energized. The offsite power grid is stable. Other LCOs were entered as required by technical specifications. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE PROVIDED BY RYAN LANE TO JEFF ROTTON AT 0012 EST ON 11/07/2014 * * *

Efforts to repair the CEA control system and realign CEA 15 with the other CEAs in its regulating group were unsuccessful. Shutdown of Unit 2 was completed at 1636 (MST) in accordance with normal operating procedures to comply with the shutdown requirements of LCO 3.1.5 Condition C. Unit 2 is currently stable in Mode 3 with the reactor coolant system at normal operating temperature and pressure. All equipment responded as expected with the exception of steam generator # 2 economizer feedwater regulating valve which remained 3 percent open. The economizer feedwater isolation valves to both steam generators were manually closed to isolate the economizer feedwater flow paths. 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 NRC Resident Inspector has been informed of the Unit 2 shutdown. Notified R4DO (Miller)

ENS 5056323 October 2014 18:06:00Palo VerdeNRC Region 4CEA non-licensed employee supervisor had a confirmed positive result for alcohol during a random fitness-for-duty test. The employee's access to the plant has been suspended. The NRC Resident Inspector has been informed.
ENS 5023729 June 2014 01:54:00Palo VerdeNRC Region 4CE

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.

  • * * UPDATE AT 0424 EDT ON 6/29/2014 FROM DENNIS MARTIN TO MARK ABRAMOVITZ * * *

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.

ENS 5015830 May 2014 17:06:00Palo VerdeNRC Region 4CEA licensed operator violated the station's fitness for duty policy due to alcohol during a random fitness-for-duty test. The employee's access to the plant has been withdrawn. The licensee will notify the NRC Resident Inspector.
ENS 5002110 April 2014 13:52:00Palo VerdeNRC Region 4CEThe 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 notification describes a previously undeclared event that is now reported pursuant to the requirements of 10 CFR 50.72(a)(3). No emergency situation exists at this time. On November 6, 2013, while operating at 100% reactor power under steady state conditions, a U-1 control room alarm was received indicating low fluid pressure in the Train 'A' hydraulic accumulator of Main Steam system isolation valve MSIV-170. A plant operator was dispatched according to the alarm response procedure to perform a pre-charge check of the accumulator. A pre-charge check returns hydraulic fluid from the accumulator to a vented tank that serves as a fluid reservoir. During this operation the fluid reservoir tank and supporting piping were damaged by the rapid expansion of nitrogen gas that had entered the hydraulic system by way of a leak across an accumulator piston O-ring. As a result of the damage and loss of hydraulic fluid, MSIV-170 and its associated hydraulic accumulators were declared inoperable at 1307 Mountain Standard Time. It was determined at that time that the failure of the fluid reservoir due to rapid expansion did not constitute an explosion and a declaration of an Unusual Event was not made according to Emergency Action Level (EAL) HU2, 'Fire within the Protected Area not extinguished within 15 minutes of detection or explosion within the Protected Area.' Subsequent review has determined that the reservoir failure should have been characterized as an explosion within the Protected Area and that a declaration of an Unusual Event should have been made per EAL HU2. The NRC Resident Inspector has been notified. The licensee has notified the State of Arizona and Maricopa County.
ENS 498077 February 2014 16:31:00Palo VerdeNRC Region 4CEThe 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 telephone notification is being made pursuant to the reporting requirements of 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of the Palo Verde Nuclear Generating Station Unit 2 'A' train Main Steam and Feedwater Isolation System (MSFIS) logic. On December 11, 2013, at approximately 2011, Mountain Standard Time, Unit 2 was shut down in Mode 4 with Reactor Coolant System (RCS) temperature at approximately 425 degrees Fahrenheit and 1900 pounds per square inch absolute. While starting up the plant following completion of repairs to the 1A reactor coolant pump, an invalid actuation of the 'A' train MSFIS fast close logic occurred due to a random electrical failure in the 'A' train MSFIS logic cabinet. This resulted in the closure of all four Main Steam Isolation Valves and the two 'A' train Economizer Feed Water Isolation Valves. No other engineered safety feature actuations occurred and none were required. The invalid actuation was initiated by a ground fault in a 30-volt direct current power supply in the 'A' train MSFIS Logic cabinet. Repairs were completed on December 12, 2013. This was a complete actuation of 'A' train MSFIS equipment and all the affected equipment responded as designed. RCS temperature and pressure were maintained stable using atmospheric dump valves. Feed water to the steam generators was being provided by Auxiliary Feed Water and was not affected by the event. The NRC Resident Inspector has been notified.
ENS 496168 December 2013 10:53:00Palo VerdeNRC Region 4CE

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.

  • * * UPDATE FROM DAVE HECKMAN TO HOWIE CROUCH AT 1632 EST ON 12/12/13 * * *

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).

ENS 496013 December 2013 04:05:00Palo VerdeNRC Region 4CEThe 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. All times described are approximate Mountain Standard Time. At 2324 on December 2, 2013, Palo Verde Nuclear Generating Station (PVNGS) Unit 3 commenced a reactor shutdown required by Technical Specification (TS) 3.1.5, Control Element Assembly (CEA) Alignment. TS Limiting Condition for Operation (LCO) 3.1.5, requires 'All full strength CEAs shall be OPERABLE, and all full strength and part strength CEAs shall be aligned to within 6.6 inches (indicated position) of all other CEAs in their respective groups.' Regulating CEA number 69 dropped to the fully inserted position at 1830 on December 2, 2013, when the circuit breaker for CEA 69 tripped open. The other 88 CEAs in the reactor were unaffected and remained fully withdrawn. Unit 3 entered LCO 3.1.5 Condition A for one misaligned CEA and reduced power to 78% within one hour in accordance with Required Action A.1. The CEA was unable to be restored to its required position within two hours in accordance with Required Action A.2 to restore CEA alignment. At 2030, Unit 3 entered Condition C of LCO 3.1.5 because of the inability to restore CEA alignment. Condition C requires the unit to be in Mode 3 in 6 hours. At 0033 on December 3, 2013 the Power Switch Assembly was replaced and tested satisfactorily. The shutdown was terminated at this time while at approximately 48% power. At 0039, Unit 3 began to withdraw CEA 69. CEA 69 was realigned with its group at 0143 and LCO 3.1.5 conditions A and C were exited. The event did not result in the unplanned 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.
ENS 496002 December 2013 23:26:00Palo VerdeNRC Region 4CEThe 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, 2013, at approximately 1758 Mountain Standard Time (MST), the Palo Verde Nuclear Generating Station (PVNGS) Unit 2 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 2 was operating normally at 100% power. Plant operators entered the emergency operations procedures and diagnosed an uncomplicated reactor trip but noted the 1A reactor coolant pump (RCP) was not running. All CEAs fully inserted into the core. Following the reactor trip, indications on the train A logarithmic (log) power nuclear instrument initially responded normally but then did not trend as expected. All other nuclear instruments responded normally and the train A log power channel was declared inoperable and technical specification limiting conditions for operation 3.3.10 and 3.3.11 were entered. No emergency classification was required per the PVNGS Emergency Plan. The Unit 2 safety related electrical busses remained energized from normal offsite power during the event. Due to planned maintenance on one switchyard breaker, the Ruud offsite power line was disconnected from the PVNGS switchyard when the Unit 2 main generator output breakers opened. There was no impact to the required circuits between the offsite transmission network and the onsite Class 1E Electrical Power Distribution System; the offsite power grid is stable. No major equipment was inoperable prior to the event that contributed to the event or complicated operator response. Unit 2 is currently stable in Mode 3 with the reactor coolant system at normal operating temperature and pressure. Preliminary information indicates the reactor trip resulted from an electrical protection trip of the power supply circuit breaker for the 1A RCP. 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 2 reactor trip. There was no impact on either Unit 1 or Unit 3.
ENS 4948229 October 2013 13:10:00Palo VerdeNRC Region 4CEAt approximately 0530 MST on October 29, 2013, an Arizona Public Service Company (APS) employee developed a personal medical condition in the Owner Controlled Area prior to entering the Protected Area at the Palo Verde Nuclear Generation Station (PVNGS). PVNGS Emergency Medical Technicians responded and transported the individual to an offsite emergency trauma center. Upon arrival at the trauma center, medical personnel declared the individual deceased at 0650 (on 10/29/13). The fatality was not work related and the individual was outside of the Radiological Controlled Area. No radioactive material or contamination was involved. No news release by APS is planned. Notifications to the Arizona Division of Occupational Safety and Health, and the Maricopa County Sheriff's Office are planned. The NRC Resident Inspectors have been notified.
ENS 494167 October 2013 12:55:00Palo VerdeNRC Region 4CEThe 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 2100 MST on 10/06/13, while performing planned routine visual examinations of the Unit 3 reactor vessel bottom mounted instrumentation (BMI) nozzles, a white residue was identified around the annulus region of BMI penetration number 3. The BMI visual examinations are performed using remote video and photographic equipment to meet the in-service inspection requirements of 10 CFR 50.55a(g)(6)(ii)(E) and ASME Code Case N-722-1. At this time, no other indications of leakage have been identified and inspections of the remaining BMI penetrations are ongoing. Following review of the photographic images by qualified engineering personnel, at 0219 (MST) on 10/07/13, it was determined, based on past and present photographic evidence, the white residue is most likely dry boric acid resulting from reactor coolant system pressure boundary leakage. An activity to sample and analyze the white residue is being planned and will be performed as soon as possible. This notification is being made for a degraded condition pursuant to the requirements of 10 CFR 50.72(b)(3)(ii)(A). The NRC Resident Inspectors have been informed of this condition.
ENS 494114 October 2013 18:20:00Palo VerdeNRC Region 4CEA review of industry operating experience regarding the impact of unfused Direct Current (DC) ammeter circuits in the control room has determined the described condition to be applicable to Palo Verde Nuclear Generating Station resulting in an unanalyzed condition with respect to 10 CFR 50 Appendix R analysis requirements. The original plant wiring design and associated analysis for the Class 1E Train B and D batteries and chargers (including the BD Swing charger) control room ampere indications do not include overcurrent protection features to limit the fault current. In the postulated event, a fire in the control room could cause one of the ammeter wires to hot short to the ground plane; simultaneously, the fire causes another DC wire from the opposite polarity on the same battery to also hot short to the ground plane. This would cause a ground loop through the unprotected ammeter wiring. This event could result in excessive current flow (heating) in the ammeter wiring to the point of causing a secondary fire in the raceway system. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10CFR50 Appendix R. The train B and D DC circuits were reviewed first since they are part of alternate safe shutdown capability for the control room fire event. An extent of condition review is ongoing for the A and C train DC circuits and other similar circuit designs that could potentially cause a secondary fire. This condition is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. Compensatory measures (fire watches) have been implemented for affected areas of the plant. The NRC Resident Inspector has been notified.
ENS 493172 September 2013 22:53:00Palo VerdeNRC Region 4CE

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).

  • * * UPDATE FROM WAYNE TIMOTHY TO JOHN SHOEMAKER AT 0352 EDT ON 9/3/13 * * *

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).

ENS 491693 July 2013 00:24:00Palo VerdeNRC Region 4CE

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.

ENS 4884925 March 2013 19:21:00Palo VerdeNRC Region 4CEThe 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 488149 March 2013 04:57:00Palo VerdeNRC Region 4CEDuring review of industry operating experience, engineering personnel determined the Palo Verde Nuclear Generating Station (PVNGS) analysis of record (AOR) for Spent Fuel Pool (SFP) criticality was not revised to support a license amendment to allow power uprate to 3990 MW thermal. The power uprate impacted the reactivity of fuel discharged to the SFP but the SFP criticality AOR was not revised to account for the impact to fuel reactivity. At 1921 (MST) on March 8, 2013, PVNGS received preliminary analysis from Westinghouse that indicates the current AOR for SFP criticality is nonconservative due to the impact of the power uprate. However, significant margin is maintained to SFP criticality at the current Technical Specification minimum SFP boron concentration requirement of 2150 parts per million (ppm) and additional margin is provided by procedure requirements which maintain SFP boron concentration greater than 4000 ppm. Margin also exists due to the maximum fuel enrichment used at PVNGS being less than the fuel enrichment assumed in the AOR. The SFP criticality analysis supports Technical Specification (TS) LCOs 3.7.15 (Fuel Storage Pool Boron Concentration) and 3.7.17 (Spent Fuel Assembly Storage) as well as TS Design Features 4.3.1 (Fuel Storage Criticality). This notification is being made pursuant to the reporting requirements of 10CFR50.72 (b)(3)(ii)(B) to describe an unanalyzed condition. The NRC Resident Inspector has been notified of this condition.
ENS 4861520 December 2012 14:07:00Palo VerdeNRC Region 4CEThe 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 telephone notification is being made pursuant to the reporting requirements of 10 CFR 50.73(a)(2)(iv)(A) and 50.73(a)(1) to describe an invalid actuation of the Palo Verde Nuclear Generating Station (PVNGS) Unit 2 essential spray pond system (SP) which serves as the ultimate heat sink as described in 10 CFR 50.73(a)(2)(iv)(B)(9). On October 25, 2012, at approximately 2108, Mountain Standard Time, during refueling outage 2R17, Unit 2 experienced an invalid actuation of the train B essential spray pond system. Testing of the train B engineered safeguards features actuation system (ESFAS) was in progress. During the test, following activities to reset the train B containment spray actuation signal (CSAS), the procedure required a check of contact status on a relay contact which provides input to the train B Load Sequencer. The guidance required the use of a digital multi-meter to perform the contact status check. When the digital multi-meter test leads were landed and removed from the circuit, the train B Load Sequencer changed output modes which resulted in automatic starting of the train B essential chilled water system, essential cooling water system, essential fuel building air filtration unit and essential spray pond system. This was a partial actuation of the train B ESF equipment and all the affected equipment responded as designed. No equipment failures resulted from the event. The event was entered into the PVNGS corrective action program. The invalid actuation was caused by an incorrect testing methodology in the procedure instructions which resulted in the unintended interaction of the digital multi-meter and the digital train B Load Sequencer. The inadequate procedures will be revised to modify the testing methodology for verification of relay contact status. The licensee has notified the NRC Resident Inspector.
ENS 483939 October 2012 16:47:00Palo VerdeNRC Region 4CEThe 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 26, 2012, at approximately 1231 Mountain Standard Time (MST), some Auxiliary Operators located in the Palo Verde Nuclear Generating Station (PVNGS) Operations Support Buildings reported to the control room that they had felt an earthquake. The US Geological Survey (USGS) internet web page recorded several small earthquakes in the Salton Sea area of Southern California. The earthquake was not felt by the control room staff and no Seismic Monitoring System alarms were received. The event was evaluated and a determination was made at that time that the event did not meet the classification criteria for declaration of an Unusual Event per the PVNGS Emergency Plan. Similarly, at 1358, personnel again reported they felt motion in the Operations Support Buildings and the USGS reported an aftershock in Southern California. The event was similarly determined to not meet the classification criteria for declaration of an Unusual Event. There were no indications of any impact to plant equipment or site operations other than being felt by personnel in the Operations Support Buildings. During post event reviews, it has been determined that these events met the classification criteria for declaration of an Unusual Event for a seismic event as specified by the PVNGS Emergency Plan. No emergency situation exists at this time. The NRC Resident Inspector was informed of this notification. The licensee notified Maricopa County and the State of Arizona.
ENS 4834726 September 2012 19:49:00Palo VerdeNRC Region 4CEThis event is being reported as a newsworthy concern to the public under 10 CFR 50.72(b)(2)(xi). All times listed are approximate Mountain Standard Time. On September 26,2012, at 13:36 pm, Arizona Public Service (APS) was notified of the intention of Maricopa County Sheriff's Office (MCSO) to issue a press release regarding an attempted entry to the Palo Verde Nuclear Generating Station's (PVNGS) Security Owner Controlled Area (SOCA) by an individual with suspicious identification earlier this morning. An individual employed with a construction project sub-contractor arrived at the SOCA checkpoint and presented suspicious identification to PVNGS security officers to gain access to the site. The individual was not admitted through the checkpoint into the SOCA. MCSO was notified and placed the individual into custody. MCSO determined the identification was false and the individual was an undocumented immigrant. The individual did not enter nor was he previously granted access to the site's Protected Areas surrounding the three units and Independent Spent Fuel Storage Installation. No evidence of malicious intent has been identified. MCSO is investigating the incident. The station notified NRC Resident Inspectors and Region IV staff of the condition. APS does not intend at this time to issue a press release, but is responding to media inquiries.
ENS 4783715 April 2012 17:13:00Palo VerdeNRC Region 4CEThe 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 April 15, 2012 at approximately 1220 Mountain Standard Time (MST), Palo Verde Unit 3 was manually tripped during low power physics testing. While conducting low power physics testing following a refueling outage, Regulating Group 1 rods were being inserted while simultaneously diluting to maintain a constant power level below the Point of Adding Heat. While inserting rods one rod deviated from its subgroup when it stopped moving. The Reactor Operator immediately ceased rod motion and the dilution was stopped. The residual positive reactivity in the core caused a corresponding reactor power increase that approached procedural power limits set forth in the low power physics testing procedure. Based on these indications, operators initiated a manual reactor trip. Following the reactor trip, all CEAs inserted fully into the core. All systems operated as expected and this event was diagnosed as an uncomplicated reactor trip. No emergency plan classification was required per the Emergency Plan. Safety related busses remained powered during the event from offsite power and the offsite power grid is stable. No major equipment was inoperable prior to the event that contributed to the event or complicated operator response. Unit 3 is stable and in Mode 3 feeding Steam Generators with Auxiliary Feedwater Pump 'N'. 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 was informed of the Unit 3 reactor trip. The electrical lineup remained normal. Decay heat is being removed via the steam bypass to the main condenser.
ENS 4768823 February 2012 00:45:00Palo VerdeNRC Region 4CE

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 1852 hours, Palo Verde Unit 1 was notified of a suspicious package located in the Owner Controlled Area outside the Protected Area. Maricopa County Sheriff's Office was contacted for assistance with a bomb disposal unit. Local media has become aware of this event and expressed interest by dispatching helicopters and television crews. There are no safety systems impacted by the package and operations personnel are not hampered in their ability to operate safety related equipment. There is no release of radioactivity to the environment as a result of this package and it has not adversely affected the safe operation of the plant or health and safety of the public. All three Palo Verde units are being maintained stable at approximately 100% power. The NRC Resident Inspector has been notified.

  • * * UPDATE FROM DELBERT ELKINTON TO VINCE KLCO ON 2/24/12 AT 1619 EST * * *

The Maricopa County Sherriff's Office bomb disposal unit responded and inspected the package. The suspicious package contained a granular absorbent material, similar to that used to clean liquid spills. The event was terminated at 23:02 AZ MST (on 2/22/12). The NRC Resident Inspector has been updated." Notified the R4DO (Deese).

ENS 4760418 January 2012 12:30:00Palo VerdeNRC Region 4CEA non-licensed contract employee supervisor had a confirmed positive for an illegal substance taken during a pre-access fitness-for-duty test. The contract employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee informed the NRC Resident Inspector.