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| Entered date | Event description | |
|---|---|---|
| ENS 42381 | 2 March 2006 18:48:00 | 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. This is a report of a situation, related to the protection of the environment, for which a notification to another government agency has been or will be made, as described in 10CFR50.72(b)(2)(xi). Specifically, the Palo Verde Nuclear Generating Station (PVNGS) notified the Arizona Department of Environmental Quality (ADEQ) of the possibility of a discharge of non-hazardous material that has the potential to cause groundwater limits to be exceeded At Palo Verde Unit 3, water was observed in a concrete pipe vault that was abutted against soil. The source of the water appeared to becoming from seals around the pipes and originating from the ground behind the pipe chase. The area behind the pipe chase contains a series of pipes buried in a layer of compacted soil. In order to characterize the water and identify its source, a pothole, approximately 13 feet deep and reinforced with a perforated drain pipe was dug in the radiological controlled area yard so that a sample of the water could be obtained. Initial results from the unit laboratory indicated the presence of tritium. A confirmatory sample was collected and analyzed by the State certified laboratory at Palo Verde that confirmed the presence of tritium at a concentration of approximately 7.14 x 10 -5 microCurie per milliliter. The Aquifer Protection Permit Aquifer Quality Limit for tritium is 2.00 x 10 -5 microCurie per milliliter. At this time we are working to identify the source. We currently have no evidence that the water has contaminated any aquifer but are continuing with our investigation. Palo Verde's ground-water monitoring program - in place since the unit operations began - has validated that no tritium has been present in any wells or aquifers in any quarterly samples. PVNGS has just finished collecting its quarterly monitoring samples. Analyzed samples have no indication of tritium. The remaining samples will be completed next week. No Technical Specification effluent limits have been exceeded. No Offsite Dose Calculation Manual (ODCM) effluent limits have been exceeded. No federal effluent limits have been exceeded. Palo Verde has not identified any health or safety risk to the public or onsite personnel. No source of leakage or release path has been identified, therefore no release rate or total quantity released has been quantified. Unit 3 is operating at approximately 100% rated thermal power at normal operating temperature and pressure. This information is also being reported to the Arizona Radiation Regulatory Agency. The licensee notified the NRC Resident Inspector. |
| ENS 41996 | 15 September 2005 14:41:00 | This is an information only notification. Commencing approximately 1 PM Mountain Standard Time, September 15, 2005, the Palo Verde Nuclear Generating Station will be performing modifications to Emergency Preparedness sirens within the 5-mile radius of the emergency planning zone (EPZ) to implement corrective action to prevent recurrence of damage due to vandalism that has occurred and been reported in previous ENS notifications (Recent Event Notifications: 41960, 41912, 41874, 41810, 41486, 41466, 41451). Palo Verde's reporting criterion includes a loss of capability to inform greater than 5% of the population (more than 106 people) within 5 miles. Six of the 12 sirens within the 5-mile radius meet this criterion. Only one of these 6 sirens will be out of service at a time for modification. 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 MCSO has been informed of the status of siren modification for each of the 6 sirens so that the contingency can be promptly implemented if an event requiring siren activation were to exist, thus no loss of capability to inform the population will occur. The licensee notified the NRC Resident Inspector. |
| ENS 41810 | 29 June 2005 13:23:00 | 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 41783 | 17 June 2005 18:39:00 | 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 15, 2005, Palo Verde Nuclear Generating Station was informed by Framatome that Thermocoax pressurizer heater elements provided for, and installed in Unit 3, were in non-conformance with specifications. Specifically, the active heating portion of the element was approximately 8 inches lower than design. The result of this error is that the active (heating) portion of the element extended into the nozzle area of the pressurizer heater sleeve and the heating effect on the pressurizer sleeve exceeded design, and possibly code-allowable temperature. Unit 3 operators entered Technical Requirements Manual LCO 3.4.103, Structural Integrity, Condition A for a ASME Code Class 1 component not conforming with requirements. The pressurizer can not be isolated and RCS temperature was already more than 50 degrees F above the minimum temperature required by NDT consideration when the condition was discovered. TLCO 3.0.100.3 is not applicable in Mode 5 and Technical Specification 3.4.9, Pressurizer, is not applicable in Mode 5. The RCS is in Mode 5 at approximately 190 degrees F and 350 psia. Engineering personnel are evaluating the code acceptability and potential for significant degradation resulting from the temperatures experienced by the pressurizer heater sleeves. On June 17, 2005, at approximately 11:00 AM MST, Palo Verde was informed that based on x-ray results of a PVNGS failed Thermocoax heater that revealed the active portion of the heater is longer than previously assumed, the metal temperatures exceeded ASME code allowable values. Stress levels are still under evaluation. This report is conservatively being placed per 10CFR50.72(b)(3)(ii)(A) based on the potential that the RCS pressure boundary may be seriously degraded, and 10CFR21(d)(3)(i) based on a defect in the pressurizer heater, a basic component, that may affect its safety function necessary to assure the integrity of the reactor coolant pressure boundary. An investigation of this condition will be conducted in accordance with the PVNGS corrective action program. The Thermocoax heater elements were installed in November 2004, when all heaters in the Unit 3 pressurizer were replaced. Due to the increased failure rate all Thermocoax heater elements have been replaced in the last 30 days with General Electric style pressurizer heater elements that were used previously. The heaters, which were also provided to SONGS 2&3 and Waterford 3, had a design variance (480 VAC single phase instead of 480 VAC 3-phase) which made them unique to Palo Verde. The impact of this variance is currently being evaluated. The licensee notified the NRC Resident Inspector. * * * UPDATE ON 8/1/05 AT 1143 EDT FROM R. BUZZARD TO P. SNYDER * * * The licensee is retracting this event based on the following: This is a retraction of ENS 41783, placed with the Headquarter Operations Center on 06/17/2005 at 1839 EDT. On June 15, 2005, Palo Verde Nuclear Generating Station was informed by Framatome that the Thermocoax pressurizer heaters provided for, and installed in Unit 3, were in non-conformance with the applicable design specification. Specifically, the heating section of the heater was manufactured approximately 8 inches longer than cited in the specification. The result of this error was that the heating section extended into the pressurizer lower head. Engineering analysis concluded that the pressurizer lower head exceeded design and ASME Code allowable temperatures. This condition was reported on June 17, 2005 (ENS 41783). Further Engineering analysis concluded that the RCS pressure boundary (pressurizer lower head) was not significantly degraded. APS has requested NRC approval for a relief request (reference letter to the NRC dated June 19, 2005). The proposed alternative discussed in this relief request provided an acceptable level of quality and safety since no significant creep effects were introduced into the Unit 3 pressurizer lower head as a result of the design non-conformance. Therefore, APS has requested that the proposed alternative be authorized pursuant to 10 CFR 50.55a(a)(3)(i). The NRC provided verbal approval for Unit 3 to continue operation. Based on the above information the "Degraded Operation" ENS notification made on June 17, is being retracted. The heater supplier, FRAMATOME ANP, INC, reported the defect in accordance with10CFR Part 21 on July 22, 2005 (ENS 41864). The licensee has retracted both the 10CFR Part 50.72(b)(3)(ii)(A) degraded condition notification and their 10 CFR Part 21 notification. Retraction of the 10 CFR Part 21 notification is based on the fact that the vendor reported the same condition. The licensee notified the NRC Resident Inspector of the retraction. Notified R4DO (D. Powers). |
| ENS 41268 | 17 December 2004 14:54:00 | On 12/17/2004 at approximately 10:53 MST, Palo Verde Nuclear Generating Station (PVNGS) notified the Department of Transportation/US. Coast Guard National Response Center of a sulfuric acid spill to the ground at the Water Reclamation Facility. The source of cooling water for PVNGS is treated sewage effluent. The effluent is conveyed to the site through approximately 35 miles of pipeline, and treated in the onsite water reclamation facility to meet plant water quality requirements. The acid spill has no impact to the radiological health and safety of the workers or the public. The spill is estimated at 1400 pounds. The reportable quantity is 1000 pounds. The sulfuric acid is classified as a CERCLA Hazardous Substance and EPCRA Extremely Hazardous Substance. The release has been isolated and the apparent cause is a leak in an underground section of pipe. There were no injuries and no known or anticipated acute or chronic health risks. The National Response Center report number is 744571. The Arizona Department of Environmental Quality was also informed at 10:51 MST. There was no impact to the three generating units from the spill at the Water Reclamation Facility which is located at a separate part of the Owner Controller Area. All 3 PVNGS Units are operating at approximately 100% in Mode 1. The NRC Resident has been notified of the event and this notification. |
| ENS 40870 | 14 July 2004 07:35:00 | The following information was received from the licensee via facsimile: 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 14, 2004, at approximately 01:35 Mountain Standard Time (MST) Palo Verde Unit 2 experienced a Main Generator Trip immediately followed by an automatic Reactor Trip. The reactor was at approximately 100% power and normal operating temperature and pressure prior to the event. The cause of the Main Generator Trip was most likely the result of electrical storm conditions present at the site at the time of the trip. Unit 2 was at normal operating temperature and pressure prior to the trip. All CEAs inserted fully into the reactor core. Heat removal was maintained to the condenser via the steam bypass control system. This was an uncomplicated reactor trip, No emergency classification was required per the Emergency Plan. No automatic ESF actuations occurred and none were required. 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. No LCOs have been entered as a result of this event. No major equipment was inoperable prior to the event that contributed to the event. Unit 2 Is stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant or the health and safety of the public. The (NRC) Senior Resident Inspector was informed of the Unit 2 reactor trip. No primary or secondary power-operated or manual relief valves lifted as a result of the plant transient. Units 1 and 3 were unaffected by the trip on Unit 2. Offsite power was maintained to Unit 2 safety busses throughout the event. |
| ENS 40561 | 2 March 2004 12:50:00 | The license provided the following via facsimile: "This ENS notification is to inform the agency of a news release that was issued 03/01/04 at 1649 Mountain Standard Time (MST) regarding the shutdown of Palo Verde Nuclear Generating Station Unit 3 and discovery of boron residue on a pressurizer heater sleeve which was reported to the Headquarters Operations Center in ENS ID 40556. The unit has been cooled down to Mode 5 in preparation of maintenance to repair the pressurizer heater sleeve. Current plant conditions are approximately 125 degrees F and 35 psia. The NRC Resident Inspector has been notified of this ENS call. |
| ENS 40533 | 20 February 2004 13:00:00 | 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 ENS notification is to inform the agency of the shutdown of Palo Verde Nuclear Generating Station Unit 2, due to increasing primary to secondary leakage, for which a news release has been issued. Unit 2 was shutdown to Mode 3 on February 19, 2004 at 18:28 Mountain Standard Time (MST) following detection of increased primary to secondary leakage at approximately 15:22 MST. The leakage was less than the Technical Specification 3.4.14(d) limit of 150 gallons per day through any one SG. Steam generator #1 was isolated at approximately 18:40 MST. The unit has been cooled down to Mode 5 in preparation of maintenance to repair the steam generator. Current plant conditions are approximately 160 degrees F and 350 psia. The decision to issue a press release was made at approximately 09:00 MST on February 20, 2004. The press release was issued at approximately 10:33 MST. The NRC Resident Inspector has been notified of this ENS call. This is the 1st cycle using these Steam Generators which were replaced in 2003. The licensee indicated that the change in in primary to secondary leakage was a step increase but was unable to accurately quantify the amount since it was less than 20 gallons per day. |
| ENS 39714 | 29 March 2003 13:41:00 | DEGRADED CONDITION DUE TO LEAKAGE AT SMALL BORE INCONEL 600 PENETRATION
The following information was received from the licensee via facsimile "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 29, 2003, at approximately 04:00 Mountain Standard Time (MST) engineering personnel performing preplanned visual examinations of reactor coolant System (RCS) piping in accordance with procedure requirements discovered boric acid residue on three RCS small bore Inconel 600 penetrations. One location was the RCS hot leg in-service thermowell 3JRCBTW0112HB. The visual observation was characterized as a small white trail of boron residue running down the hot leg approximately 2 inches. There were no signs of dripping, spraying, puddles of liquid, or liquid running down the nozzle or hot leg. The residue appeared dry. The other two were on pressurizer heater sleeves (nozzles) A-4 and A-18. The visual observation at these two locations was characterized as a small white buildup of boron residue around the heater sleeve as the sleeve enters the pressurizer bottom head. There does not appear to be residue running down the outside of the sleeves. There were no signs of dripping, spraying, puddles of liquid, or liquid running down the nozzle or (pressurizer). The residue appeared dry "Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.4.14 permits no reactor coolant system (RCS) pressure boundary leakage and therefore, the discovery of leakage (presumed boric acid residue) from the hot leg thermowell and the pressurizer heater sleeves was a degradation of a principal safety barrier. Therefore, the ENS notification of this event is in accordance with 10CFR50.72(b)(3)(ii). The control room personnel entered LCO 3.4.14 Condition B and are continuing to place the plant in Mode 5. The RCS was being cooled down in preparation for Unit 3's tenth refueling outage. At the time of discovery, the RCS was at approximately 520 degrees F and 2218 psia "An investigation of this event will be conducted in accordance with the PVNGS (Palo Verde Nuclear Generating Station) corrective action program. The cracking of Alloy 600 components both at Palo Verde and industry-wide has been attributed to axially oriented, primary water stress corrosion cracking (PWSCC). PWSCC is not considered a significant threat to the structural integrity of the RCS boundary, thermowell, or heater sleeves as this type of cracking typically results only in small leaks "The bases for this conclusion is that if PWSCC occurred at Palo Verde, the cracks would be predominately axial in orientation. As in this case, the cracks would result in visibly detectable leakage that would be apparent during visual examinations, performed as part of walkdown inspections, before significant damage to the reactor coolant boundary occurred "Palo Verde has a program for replacing the Alloy 600 hot leg thermowells. This thermowell was scheduled for replacement during this refueling outage. The plans to replace the thermowell remain unchanged "A mechanical nozzle sleeve assembly (MNSA) will be installed on each of the pressurizer heater sleeves "No ESF actuations occurred and none were required. There were no structures, systems, or components that were inoperable at the time of discovery that contributed to this condition. There were no failures that rendered a train of a safety system inoperable and no failures of components with multiple functions were involved. The event did not result in the release of radioactivity to the environment and did not adversely affect the safe operation of the plant or health and safety of the public. The licensee has informed the NRC Resident Inspector. |