ENS 45425
ENS Event | |
|---|---|
11:50 Oct 11, 2009 | |
| Title | Reactor Water Level Indication Inoperable |
| Event Description | 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. |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 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 | |
| Time - Person (Reporting Time:+3.6 h0.15 days <br />0.0214 weeks <br />0.00493 months <br />) | |
| Opened: | James W Moreland 15:26 Oct 11, 2009 |
| NRC Officer: | Charles Teal |
| Last Updated: | Oct 23, 2009 |
| 45425 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Palo Verde with 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 | |
WEEKMONTHYEARENS 557962022-03-19T20:06:00019 March 2022 20:06:00
[Table view]10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Technical Support Center (TSC) ENS 554442021-09-01T03:50:0001 September 2021 03:50:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Seismic Monitoring System ENS 542722019-09-12T01:24:00012 September 2019 01:24:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Main Steam Line Radiation Monitor Communication Failure ENS 535752018-08-31T07:00:00031 August 2018 07:00:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Unplanned Loss of Steam Line Monitor Channels ENS 535222018-07-23T07:00:00023 July 2018 07:00:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Unplanned Loss of Steam Line Monitor Channels ENS 532152018-02-16T04:53:00016 February 2018 04:53:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Automatic Reactor Trip Due to Low Departure from Nucleate Boiling Signal ENS 529892017-09-22T22:00:00022 September 2017 22:00:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Seismic Monitoring Computer Out-Of-Service ENS 522292016-09-09T01:56:0009 September 2016 01:56:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of the Seismic Monitoring System Computer ENS 510412015-05-04T10:20:0004 May 2015 10:20:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Seismic Monitoring System Out of Service ENS 496162013-12-08T15:00:0008 December 2013 15:00:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Assessment Due to Technical Support Center Uninterruptable Power Supply Planned Replacement ENS 488492013-03-25T17:30:00025 March 2013 17:30:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness One Alert Notification Siren Removed from Service for Planned Maintenance ENS 474592011-11-19T15:28:00019 November 2011 15:28:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition the Low Pressure Safety Injection System Was Subjected to High Pressure Resulting in Both Trains Being Declared Inoperable ENS 472742011-09-18T15:30:00018 September 2011 15:30:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Technical Support Center Out of Service Due to Planned Maintenance ENS 472682011-09-14T17:23:00014 September 2011 17:23:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Two Public Warning System Sirens ENS 463312010-10-14T16:15:00014 October 2010 16:15:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Emergency Sirens Will Be Taken Out of Service for Planned Maintenance ENS 461882010-08-18T14:42:00018 August 2010 14:42:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Several Public Warning System Sirens ENS 461402010-07-30T14:20:00030 July 2010 14:20:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Emergency Siren ENS 459682010-06-01T14:15:0001 June 2010 14:15:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Public Warning System Siren Out of Service ENS 454252009-10-11T11:50:00011 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 ENS 449242009-03-21T16:00:00021 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 ENS 446922008-12-02T23:20:0002 December 2008 23:20:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of One (1) Emergency Siren ENS 446062008-10-28T16:00:00028 October 2008 16:00:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Maintenance on Public Prompt Notification System Emergency Sirens ENS 438242007-12-04T14:00:0004 December 2007 14:00:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness, 10 CFR 50.72(b)(3)(xii), Transport of a Contaminated Person Offsite Offsite Notification Due to Potential Loss of Three Sirens ENS 427012006-07-12T14:30:00012 July 2006 14:30:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness One Siren in Ep Zone Is Out of Service ENS 426512006-06-18T21:55:00018 June 2006 21:55:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Loss of Onsite Emergency Safety Function - "B" Edg Failed to Start During Test Run ENS 420502005-10-11T23:02:00011 October 2005 23:02:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Tech Spec Required Shutdown of Both Unit 2 and 3 ENS 419412005-08-23T20:49:00023 August 2005 20:49:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Two Emergency Sirens Inoperable ENS 419122005-08-11T15:45:00011 August 2005 15:45:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness One Emergency Preparedness Siren Out of Service ENS 418742005-07-26T23:35:00026 July 2005 23:35:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Inoperable Single Emergency Siren ENS 418102005-06-29T11:43:00029 June 2005 11:43:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Evacuation Siren Inoperable ENS 414862005-03-13T01:45:00013 March 2005 01:45:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Operability of One Emergency Evacuation Siren ENS 414662005-03-07T15:10:0007 March 2005 15:10:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Two Emergency Sirens Inoperable ENS 414512005-02-28T21:57:00028 February 2005 21:57:00 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Major Loss of Siren Coverage within the Emergency Planning Zone ENS 412242004-11-24T19:20:00024 November 2004 19:20:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Eccs Loops Declared Inoperable in Support of Log Term Accident Mitigation ENS 409132004-07-31T01:45:00031 July 2004 01:45:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Air Void in Post-Loca Recirculation Piping System 2022-03-19T20:06:00 | |