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| Discovered date | Reporting criterion | Title | Event description | |
|---|---|---|---|---|
| ENS 45425 | 11 October 2009 11:50:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Reactor Water Level Indication Inoperable | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS (Emergency Notification System) or under the reporting requirements of 10CFR50.73. On 10/11/2009 at 0450 MST Palo Verde Nuclear Station Unit 1 declared both trains of the Qualified Safety Parameter Display (QSPDS) inoperable due to the discovery that an installed temporary modification (TMOD) impacted the reactor vessel level indication parameter in a non-conservative manner. The modification jumpered failed heater junction thermal connections (HJTC) at the heated and unheated HJTC points. Unit 1 has two failed detectors with TMODs installed. During a design event where these detectors would be needed, these detectors will not alarm at the correct vessel levels. The emergency operating procedures use this indication and pressurizer level indications (which are unaffected by this condition) to throttle safety injection flow during certain accidents. With the TMOD providing incorrect indication the operators could throttle flow when full flow should be maintained. In addition the QSPDS reactor level indication is used in the Emergency Plan to classify emergencies. The standard Appendix 101 to Palo Verde emergency procedures provides guidance for an alternate method for determining reactor vessel level when RVLMS (Reactor Vessel Level Monitoring System) is out of service. This alternate method determines level by manually determining sub-cooled, saturation or superheated conditions based upon input of reactor vessel pressure and the "raw" QSPDS - RVLMS thermocouple temperature indications. This compensatory measure ensures that classification of events can continue to be completed in a timely manner. Unit 1 has entered the LCO (Limiting Condition of Operation) required action for this condition which requires at least one channel be restored to operable status within 7 days. Unit 2 is in a refueling and is not impacted at this time. Unit 3 does not have the TMOD installed. According to the licensee Train A TMOD which was installed 2/3/08 and the train B TMOD which was installed 12/12/08. The licensee checked the installation of these TMODs after reviewing operating experience reports from Calvert Cliffs. The licensee has notified the NRC Resident Inspector.
On 10/11/2009 at 12:26 MST Palo Verde Nuclear Station Unit 1 reported the inoperability of both trains of the Qualified Safety Parameter Display System (QSPDS) due to the discovery that an installed temporary modification impacted the reactor vessel water level indication parameter in a non-conservative manner. After further Operations and Engineering review it was concluded that the modification, installed due to one inoperable heated junction thermal couple (HJTC) in each train, does not result in the inoperability of either train of QSPDS since the Technical Specification required number of heated junction thermal couples (HJTC) (two each in the upper and lower level indication) remain operable with the temporary modification installed. In addition, the Control Room operators would understand the QSPDS indication and would correctly control the plant per the emergency operating procedures using this indication along with pressurizer level indication to throttle safety injection flow during certain accidents. The QSPDS reactor level indication is also used in the Emergency Plan to classify emergencies and the modification would not impact this function. Unit 1 has exited the LCO Condition for two inoperable QSPDS reactor vessel water level instrument channels. The licensee has notified the NRC Resident Inspector. R4DO (Okeefe) notified. |
| ENS 44924 | 21 March 2009 16:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Various Control Room Annunciators and Alarms Out of Service Due to Maintenance on Power Supply | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73. On March 21, 2009, from approximately 09:00 Mountain Standard Time (MST) until 14:00 MST, Palo Verde maintenance personnel will be performing scheduled maintenance to repair one of two redundant 120 VAC power supplies in Unit 2 that provides power to various alarms in the main control room. This work will require both power supplies to be de-energized resulting in approximately 50 percent of the Unit 2 plant annunciators being unavailable. The following compensatory measures will be in place for the duration of the scheduled work: Other assessment indications will remain available:
Plant Monitoring System
Qualified Safety Parameter Display System
Emergency Response Facility Data Acquisition System
No changes in plant power or operating mode are planned.
A third licensed operator will be in the control room.
The NRC Resident Inspector has been notified of the scheduled outage and this ENS call.
The power supply was successfully repaired and all annunciators were restored to normal as of 1515 MST. The Licensee will notify the NRC Resident Inspector. Notified R4DO (Hay) and NRR EO (Holian). |
| ENS 43717 | 12 October 2007 01:47:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Erdads/Spds Display | On 10/11/2007 at 2147, the ERDADS SPDS displays for Unit 1 were discovered out of service, rendering the majority of process parameters and trends unreadable from the display screens in the control room, TSC, and EOF. This information was also not available to the NRC via the ERDS. However, the process parameters and alarm capabilities are available to operating personnel via redundant control room and plant instrumentation. Information regarding main steam line radiation monitoring, meteorological data, and information provided by the Qualified Safety Parameter Display System (QSPDS) (i.e. RCS sub cooling, reactor vessel level, and core exit temperature) is available on the ERDADS terminals and is also available to the NRC via the ERDS. The ERDS Link to the NRC from both Unit 1 and Unit 2 remains functional. Troubleshooting by the site maintenance and engineering personnel is ongoing. This Non-Emergency Notification is being made pursuant to 10CFR50.72(b)(3)(xiii) regarding loss of emergency assessment capability. The licensee will notify the NRC Resident Inspector. |
| ENS 43678 | 1 October 2007 18:15:00 | Other Unspec Reqmnt | Replacing the Emergency Response Facility Computer System | The Plant Process computer system (Emergency Response Facility Computer System) will be taken out of service for approximate 3 week period starting October 1, 2007, to implement a planned modification. The current ERFCS is being replaced and a computer outage is required for the installation of the new ERFCS. During this time period Emergency Response Data System (ERDS) and Safety Parameter Display System (SPDS) functions will not be available. However, the Qualified Safety Parameter Display System (QSPDS) will still be operable in the Control Room. This notification is being made to inform the NRC that the ERDS will be unavailable until this modification is complete. The operation of the plant systems will not be affected due to this planned action. ERDS and SPDS parameters will be monitored by control board indications. All contingency actions required by ERFCS-3, ERFCS Maintenance Outage Plant Mode 1, have been taken. Meteorological data to support the Emergency Response Organization (ERO) will be obtained from the local national weather service (if needed) as described in our Radiological Response Plan. A follow up notification, to the NRC will be given once ERDS and SPDS are returned to service. The NRC Resident Inspector has been informed.
The licensee completed planned modifications and fully restored the Plant Process computer system (Emergency Response Facility Computer System). The licensee notified the NRC Resident Inspector. Notified R4DO (Powers) , T. Kardaras (email). |
| ENS 41958 | 29 August 2005 17:45:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Safety Parameter Display System and Emergency Response Data System Planned Upgrade Outage | On August 29, 2005 at about 1045 PDT, San Onofre Nuclear Generating Station, Unit 3, removed a portion of the Safety Parameter Display System (SPDS) and the Emergency Response Data System (ERDS) from service for a planned upgrade to ensure long-term reliability and improve the human-machine interface. This work is expected to complete within seven days. The SPDS emergency assessment function at San Onofre is implemented by a combination of the Qualified Safety Parameter Display System (QSPDS) and the Critical Function Monitoring System (CFMS). The QSPDS portion, which provides emergency assessment capability to plant operators in the control room, will remain functional. The CFMS portion, which receives input from the QSPDS, implements the ERDS and communicates data to the Technical Support Center and Emergency Offsite Facility. Only the CFMS and ERDS are impacted by this upgrade. This planned CFMS outage is being reported in accordance with10CFR50.72(b)(3)(xiii) as a courtesy notification even though only a portion of the SPDS will be removed from service and preplanned compensatory measures will be in place for the duration of the work. "At the time of this report, Unit 2 and Unit 3 were operating at about 99 percent and 100 percent power, respectively. The NRC Resident Inspectors will be notified of this occurrence and will be provided with a copy of this report. * * * UPDATE ON 09/04/05 AT 0249 FROM C. WILLIAMS TO P. SNYDER * * * The CFMS upgrade work was completed on September 3, 2005 at 2255 PDT. The SPDS and ERDS have been returned to service. The NRC Resident Inspectors will be notified of this occurrence. Notified R4DO (Smith). |
| ENS 41533 | 28 March 2005 19:21:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Outage of Spds Due to System Upgrade | The licensee faxed the following information: On Tuesday, March 29, 2005, Surry Power Station will remove a portion of the Emergency Response Facilities Computer System (ERFCS) in the Main Control Room (MCR) for planned upgrades to a new system for increased reliability and improved human interface design. For approximately 1 week, there will not be a qualified Safety Parameter Display System (SPDS) available in the MCR. During the time period that SPDS is unavailable in the MCR while the upgrade is occurring, the replacement SPDS system is available in the MCR on the Plant Computer System (PCS), but final testing will not qualify the software until completion of this work. There will also remain one ERFCS terminal operable in both the Technical Support Center (TSC) and Local Emergency Operations Facility (LEOF) with operable SPDS throughout the duration of this work. The Emergency Response Data System (ERDS) will remain available from those terminals for the duration of this planned work and normal data transmission capability will remain in the event of an emergency. Since SPDS will be out of service for greater than 1 hour, this report is being submitted in accordance with the guidance in 10CFR50.72(b)(3)(xiii) and NUREG-1022. The licensee has notified the NRC Resident Inspector.
The following information was provided by the licensee via facsimile: This report is an update to previous report EN #41533, dated 03/28/05, regarding the availability of the Emergency Response Facilities Computer System (ERFCS) and Safety Parameter Display System (SPDS) in the main control room for Surry Power Station. The ERFCS and SPDS modifications and testing were completed at 1630 hours on 04/07/05. These functions have been transferred to the Surry Plant Computer System. Senior NRC resident, Norm Garrett was notified via alphanumeric page. Notification was made to NRC duty officer Bill Huffman. R2DO (Rogers) notified. |
| ENS 41477 | 9 March 2005 08:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Loss of the Emergency Response Data System | The following information was obtained from the licensee via e-mail (licensee text in quotes): On Thursday, March 10, 2005 San Onofre Nuclear Generating Station, Unit 2, will remove a portion of the Safety Parameter Display System (SPDS) and the Emergency Response Data System (ERDS) from service for a planned upgrade to ensure long-term reliability and improve the human-machine interface. This work is expected to complete within seven days. The SPDS emergency assessment function at San Onofre is implemented by a combination of the Qualified Safety Parameter Display System (QSPDS) and the Critical Function Monitoring System (CFMS). The QSPDS portion, which provides emergency assessment capability to plant operators in the control room, will remain functional. The CFMS portion, which receives input from the QSPDS, implements the ERDS and communicates data to the Technical Support Center and Emergency Offsite Facility. Only the CFMS and ERDS are impacted by this upgrade. This planned CFMS outage is being reported in accordance with 10CFR50.72(b)(3)(xiii) as a courtesy notification even though only a portion of the SPDS will be removed from service and preplanned compensatory measures will be in place for the duration of the work. At the time of this report, Unit 2 and Unit 3 were operating at about 79 percent and 99 percent power, respectively. The NRC Resident Inspectors will be notified of this occurrence and will be provided with a copy of this report. Should an emergency event occur, the licensee intends to transmit emergency response data to the NRC via facsimile and voice via the emergency notification system. No electronic data will be sent to the NRC Operations Center for the outage duration.
The CFMS upgrade work was completed on March 17, 2005 at 2310 PST. The SPDS and ERDS have been returned to service. The licensee has notified the NRC Resident Inspector. Notified R4DO (Farnholtz). |