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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.

On June 14, 2004, at approximately 07:44 Mountain Standard Time (MST) all three units at the Palo Verde Nuclear Generating Station experienced automatic reactor trips coincident with a grid disturbance and loss of offsite power in the Palo Verde Switchyard. Unit 2 declared an ALERT Emergency Plan classification at approximately 07:54 due to a loss of AC power to essential buses reduced to a single power source for greater than 15 minutes such that any additional single failure would result in a station blackout. Subsequently, at 09:51 Unit 2 downgraded the Emergency Plan classification to a NOTIFICATION OF UNUSUAL EVENT when AC power was restored from a single essential bus to both essential buses. Units 1 and 3 declared a NOTIFICATION OF UNUSUAL EVENT at 07:53 MST due to a loss of offsite power to essential buses for greater than 15 minutes. The NOTIFICATION OF UNUSUAL EVENT was terminated for all 3 units at 12:07 MST. Unit 1 and 2 manually initiated a Main Steam Isolation System ESF actuation by procedure. Unit 3 received an automatic Main Steam Isolation System ESF actuation. Due to the loss of offsite power, the Emergency Plan Technical Support Center (TSC) was unavailable. The Unit 2 Satellite TSC was to be staffed by the Emergency Response Organization in response to the loss of assessment capability. Power to the TSC has since been restored. The Emergency Plan ALERT declaration includes staffing of the Joint Emergency New Center to address expected media interest. All three units were at normal operating temperature and pressure prior to the trip. All CEAs inserted fully into the reactor cores. All Emergency Diesel Generators (EDGs) (2 per unit) associated with each of the 3 units started as expected in response to the loss of offsite power to their safety buses. Unit 2's train "A" EDG started, but did not indicate volts or amps and was manually shutdown. The offsite power grid had several perturbations for approximately one hour following the event but has been stable since. LCO 3.8.1, AC Sources - Operating, was entered in each unit as a result of this event. Heat removal is to atmosphere via atmospheric dump valves in natural circulation. Main steam safety valves may have lifted for a brief time. Restoration of forced reactor coolant circulation is pending assurance that the offsite power grid can reliably support the load. No major equipment was inoperable prior to the event that contributed to the event. All 3 units are stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant NRC Resident Inspector was notified. FBI Jeff Muller and Mr. Rosales (Mexican National Commission of Nuclear Safety and Safeguards (CNSNS)) were notified.

• * * Update at 1815 @ 06/14/04 * * *

Notified Reg 4 RDO (Graves), NRR (Bateman), DHS (Lee), FEMA (Canupp), DOE (Sal Moroni), EPA (Stalcup), EPA (Crews), HSS (Davidson), and Mexico (Rosales) NOTE: See events 40815, 40816 and 40818

On June 14, 2004, at approximately 07:44 Mountain Standard Time (MST) all three units at the Palo Verde Nuclear Generating Station experienced automatic reactor trips coincident with a grid disturbance and loss of offsite power in the Palo Verde Switchyard. Unit 3 declared a NOTIFICATION OF UNUSUAL EVENT at 07:53 MST due to a loss of offsite power to essential buses for greater than 15 minutes. The NOTIFICATION OF UNUSUAL EVENT was terminated at 12:07 MST. Unit 3 received an automatic Main Steam Isolation System ESF actuation. Due to the loss of offsite power, the Emergency Plan Technical Support Center (TSC) was unavailable. The Unit 2 Satellite TSC was to be staffed by the Emergency Response Organization in response to the loss of assessment capability. Power to the TSC has since been restored. The unit was at normal operating temperature and pressure prior to the trip. All CEAs inserted fully into the reactor cores. All Emergency Diesel Generators (EDGs) (2 per unit) associated with the unit started as expected in response to the loss of offsite power to their safety buses. The offsite power grid had several perturbations for approximately one hour following the event but has been stable since. LCO 3.8.1, AC Sources - Operating, was entered as a result of this event. Heat removal is to atmosphere via atmospheric dump valves in natural circulation. Main steam safety valves may have lifted for a brief time. Restoration of forced reactor coolant circulation is pending assurance that the offsite power grid can reliably support the load. No major equipment was inoperable prior to the event that contributed to the event. The Unit is stable at normal operating temperature and pressure in Mode 3. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant NRC Resident Inspector was notified. FBI Jeff Muller and Mr. Rosales (Mexican National Commission of Nuclear Safety and Safeguards (CNSNS)) were notified.

• * * Update at 1815 @ 06/14/04 * * *

Notified Reg 4 RDO (Graves), NRR (Bateman), DHS (Lee), FEMA (Canupp), DOE (Sal Moroni), EPA (Stalcup), EPA (Crews), HSS (Davidson), and Mexico (Rosales) Note: see related events 40815 , 40814 and 40818

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 November 24, 2004, at approximately 12:20 Mountain Standard Time (MST), Palo Verde Nuclear Generating Station Unit 3 was operating at 0% power at approximately normal operating temperature and pressure when 3 of the 4 ECCS injection check valves were identified to be in a degraded condition. While performing normal torque verifications on the bonnet bolts for these check valves, it was identified that the graphoil seals were degraded in that the seal material had extruded past the retaining ring. Although there was no evidence of actual leakage associated with these valves, the long term integrity of the valves during post accident operation could not be assured. As a result, the Operators conservatively declared both trains of ECCS inoperable per LCO 3.5.3 and 3 of 4 Safety Injection Tanks inoperable per LCO 3.5.1, requiring entry into LCO 3.0.3. Operations also declared both RCS loops inoperable per LCO 3.4.5. A cooldown and depressurization of the RCS is in progress to Mode 5. Unit 3 was preparing for Mode 2 entry following a refueling outage when the degraded check valve seals were identified. Engineering continues to evaluate this condition. There were no RPS/ESF actuations, and none were required. There were no structures, systems or components that were inoperable at the start of event that contributed to the event. This condition 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. This condition did not adversely affect the safe operation of the plant or health and safety of the public. The NRC Resident Inspector has been notified of this condition and this ENS notification.

• * * RETRACTION FROM DAN MARKS TO BILL HUFFMAN AT 14:52 EST ON 12/14/04 * * *

Engineering has determined that these RCS PIV's (Pressure Isolation Valves) were always capable of performing their safety function. The extrusion of the graphite seal material for the check valves did not affect the capability of the RCS PIV check valves safety function and did not present a danger to the pressure boundary of the RCS. It was estimated that no more than about 5% of the graphite material was extruded. The loss of this small amount of packing material, did not challenge the integrity of the seal. This is based on industry experience and the results of Palo Verde tests. Also, the functionality of the SI check valves disc was not compromised since the internal disc to seat clearances achieved were within the range desired. Nevertheless, the seals for valves SIEV227, 237 & 247 were replaced while in Mode 5 to add additional margin to the joint design. LCO 3.0.3 and the other impacted LCO entries (3.4.5, 3.5.1, 3.5.3) were conservative and were not required. Therefore, this 10CFR50.72(b)(3)(v)(D) notification, ENS ID # 41224 of 11/24/2004, 20:01 ET, is retracted and no followup LER will be submitted for this event. The NRC Resident Inspector has been notified of the retraction and this notification. R4DO (Pick) notified.

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 will be made via the ENS or under the reporting requirements of 10CFR50.73. On April 23, 2005, at approximately 11:35 Mountain Standard Time (MST) engineering personnel performing preplanned in-service examinations of reactor vessel head vent penetration in accordance with procedure requirements discovered two axial indications in the Palo Verde Nuclear Generating Station Unit 2 reactor vessel head vent penetration. The indications are located on the inner diameter surface of the pipe adjacent to the J-weld to the head and are part of the RCS pressure boundary. The indications are characterized as axial, estimated less than 0.080 inch deep, approximately 0.1 inch long, and oriented at approximately 90 degrees from each other. The indications are not through-wall. There is no evidence of RCS pressure boundary leakage. Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.4.14 permits no reactor coolant system (RCS) pressure boundary leakage and there is no evidence of pressure boundary leakage. Nevertheless, the indications are being conservatively identified as abnormal degradation of the reactor coolant system pressure boundary and will necessitate taking corrective action to restore the barrier's capability. Therefore, the ENS notification of this event is in accordance with 10CFR50.72(b)(3)(ii)(A). The Unit had been shutdown for its 12th refueling outage and was being maintained de-fueled for maintenance. 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.

An investigation of this event will be conducted in accordance with PVNGS corrective action program.

The NRC Resident Inspector was notified of this event by the licensee.

On August 11, 2005 at approximately 08:45 Mountain Standard Time (MST), the Palo Verde Emergency Preparedness Department identified an inoperable single siren (#15). While reviewing the siren monitoring computer log, an Information Services Technician received a 'no response' signal on siren #15. Upon investigation, siren #15 was found inoperable. The siren was vandalized by destroying the siren controller case and stealing the internal battery. The affected siren is estimated to impact approximately 496 members of population in the emergency planning zone (EPZ) beyond 5 miles but within 10 miles. Palo Verde's reporting criterion is a loss of capability to inform greater than 10% of the population beyond 5 miles but within 10 miles. This call is being placed due to the relatively large segment of the population affected and the uncertainty of the length of time that will be needed to restore the siren to operable condition. The Palo Verde Emergency Plan (section 6.6.2.1) has a contingency for dispatching Maricopa County Sheriff's Office (MCSO) vehicles with loud speakers to alert persons within the affected area(s) when sirens are inoperable.

The County was informed at 09:05 MST to implement the MCSO notification if a need arises. There are no events in progress that require siren operation. The licensee notified the NRC Resident Inspector.

On July 1, 2006, at approximately 19:28 MST Palo Verde Unit 3 experienced a manual reactor trip from approximately 100% rated thermal power due to a large leak in the condensate system. The sight glass for the 'A' condensate demin vessel blew out of the vessel creating an approximate 6 inch diameter hole. Several thousand gallons of condensate were discharged to the Turbine Building and the environment. Radiation Protection has sampled the condensate water and have verified no activity is present. Unit 3 was at normal operating temperature and pressure prior to the trip. The 'A' Main feedwater pump tripped on low suction pressure and a Reactor Power Cutback Signal was received. Condenser hotwell levels continued to decrease. When the main control board annunciator for the 'B' Main Feedwater Pump Trip Circuit Energized was received the reactor was manually tripped. All CEAs fully inserted into the reactor core. The event was diagnosed as an uncomplicated reactor trip. No ESF actuations occurred and none were required. Safety related buses remained energized during and following the reactor trip. The offsite power grid is stable. No significant LCOs have been entered as a result of this event. There was no loss of normal heat removal capabilities, or loss of any safety functions associated with this event. No major equipment was inoperable prior to the event that contributed to the event. No primary or secondary safety valves lifted during the event. 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. Unit 3 is stable at normal operating temperature and pressure in Mode 3. There is no estimated time and date for the Unit 3 restart at the time this call is being made. AFW is being used to feed the steam generators and is discharging steam to the main condenser. The licensee stated that the leak has been secured and that there is no significant standing water in the turbine building lower levels. All the water has drained into sumps or out doors. There does not appear to be any electrical or personnel safety hazards as a result of the water leak. The licensee notified the NRC Resident Inspector.

• • • UPDATE FROM RAY BUZZARD TO JOHN KNOKE AT 17:28 ON 07/03/06 ***

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 a follow-up to the manually initiated reactor trip event reported on July 1, 2006 (ENS 42681). The notification indicated that the reactor was manually tripped from approximately 100% rated thermal power due to a large leak in the condensate system. Prior to the transient the unit was operating at approximately 100 % rated thermal power, however, the manual trip was actually initiated from approximately 55% rated thermal power following a reactor power cutback caused by the loss of the A train main feedwater pump on low suction pressure. In addition, the ENS report stated that Radiation Protection had sampled the condensate water and verified no activity is present. The condensate actually was found to contain tritium at a concentration of 1.22E-5 uCi/ml. The water from the spill flowed to the onsite storm drains, was captured behind dams, and transferred to the onsite retention basins. Samples of resin from the spill were also collected, analyzed by gamma spectroscopy, and found to not contain licensed radioactive material. The licensee notified the NRC Resident Inspector. Notified R4DO (Shannon)