ENS 42938
ENS Event | |
|---|---|
06:53 Oct 27, 2006 | |
| Title | Loss of Power to the Unit 1 and Unit 3 Train B Safety Buses with Emergency Diesel Generator Actuation |
| 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 or under the reporting requirements of 10CFR50.73.
On October 26, 2006, at approximately 23:53 Mountain Standard Time (MST) a valid actuation of the Palo Verde Nuclear Generating Station Unit 1 Train B Emergency Diesel Generator (EDG) and Unit 3 Train B EDG occurred as a result of undervoltage on their respective safety buses. Both EDGs started and loaded as designed. No Emergency Plan declaration was made and none was required. The loss of power to the two safety buses was the result of an apparent spurious protective relay actuation of Startup Transformer X01 output breakers to Unit 1 NAN-S06 and Unit 3 NAN-S06 busses. Unit 1 NAN-S06 bus was being supplied by its Alternate breaker (1ENANS06F) and Unit 3 NAN-S06 was being supplied by its Normal breaker (3ENANS06C). Prior to the event, maintenance personnel were restoring potential Transformer (PT) fuses at Unit 1 breaker 1ENANS06, Cubicle G. Preliminary information is that the two simultaneous LOP conditions occurred when the outer doors were closed on 1ENANS06, Cubicle G. This condition apparently caused the output breakers of Startup Transformer X01 to open. There was no electrical fault or damage to any electrical components. Both Units 1 and 3 entered Technical Specification LCO 3.8.1 Condition A for one (of two) required offsite circuits inoperable. [The licensee is] proceeding with restoration of Normal offsite power to each safety bus in Units 1 and 3. Once offsite power is restored, the LCOs will be exited and the Unit 1 and 3 train B EDGs will be returned to standby. Both Unit 1 and Unit 3 were at approximately 100% power, at normal operating temperature and pressure prior to and following the EDG actuations. Unit 2 was defueled and was not impacted by the electrical disturbance. No other ESF actuations occurred and none were required. No major equipment was inoperable prior to the event that contributed to 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. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+0.17 h0.00708 days <br />0.00101 weeks <br />2.32866e-4 months <br />) | |
| Opened: | James Moreland 07:03 Oct 27, 2006 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Oct 27, 2006 |
| 42938 - NRC Website
Loading map... {"minzoom":false,"maxzoom":false,"mappingservice":"leaflet","width":"350px","height":"250px","centre":false,"title":"","label":"","icon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"zoom":6,"defzoom":14,"layers":["OpenStreetMap"],"image layers":[],"overlays":[],"resizable":false,"fullscreen":false,"scrollwheelzoom":true,"cluster":false,"clustermaxzoom":20,"clusterzoomonclick":true,"clustermaxradius":80,"clusterspiderfy":true,"geojson":"","clicktarget":"","imageLayers":[],"locations":[{"text":"\u003Cb\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003E\u003Ca class=\"mw-selflink selflink\"\u003EENS 42938\u003C/a\u003E - \u003Ca href=\"/Palo_Verde\" title=\"Palo Verde\"\u003EPalo Verde\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003ELoss of Power to the Unit 1 and Unit 3 Train B Safety Buses with Emergency Diesel Generator Actuation\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 42938 - Palo Verde\n","link":"","lat":33.386894444444444,"lon":-112.86263333333333,"icon":"/w/images/9/93/Arizona_Public_Service_icon.png"}],"imageoverlays":null} | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 570472024-03-24T23:34:00024 March 2024 23:34:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Specified System Actuations of Unit 2 Train B Emergency Diesel Generator and Train B Auxiliary Feedwater ENS 565512023-06-02T11:05:0002 June 2023 11:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 564592023-04-09T04:44:0009 April 2023 04:44:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Loss of Reactor Coolant Pumps ENS 560442022-08-15T00:02:00015 August 2022 00:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuations of Unit 1 and Unit 3 Emergency Diesel Generators and Unit 1 Auxiliary Feedwater Pump ENS 558782022-05-05T02:55:0005 May 2022 02:55:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Unit 2 and Unit 3 Emergency Diesel Generators and Unit 3 Auxiliary Feedwater Pump ENS 555342021-10-20T21:46:00020 October 2021 21:46:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Specified System Actuations of Unit 1 and Unit 3 Emergency Diesel Generators ENS 542242019-08-16T15:21:00016 August 2019 15:21:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Turbine Trip ENS 534772018-06-27T07:00:00027 June 2018 07:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip on Low Steam Generator Water Level ENS 466332011-02-22T03:01:00022 February 2011 03:01:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Auto Start and Load of Edgs on Units 1&3 Following Loss of Start-Up Transformer ENS 465562011-01-20T01:41:00020 January 2011 01:41:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Main Feedwater Pump Trip ENS 429382006-10-27T06:53:00027 October 2006 06:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Power to the Unit 1 and Unit 3 Train B Safety Buses with Emergency Diesel Generator Actuation ENS 426092006-05-30T15:13:00030 May 2006 15:13:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Power to Train "a" 4 Kv Safety Bus ENS 425592006-05-06T23:35:0006 May 2006 23:35:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Emergency Diesel Generator Due to Low Voltage Condition ENS 424682006-04-03T03:54:0003 April 2006 03:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Trip During Testing ENS 413792005-02-07T05:19:0007 February 2005 05:19:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Start Due to Bus Deenergization ENS 413042004-12-31T17:42:00031 December 2004 17:42:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Plant Had Auto Start and Loading of Two Emergency Diesel Gererators ENS 408162004-06-14T14:44:00014 June 2004 14:44:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Due to Reactor Trip Due to Loss of Off Site Power ENS 408152004-06-14T14:44:00014 June 2004 14:44:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Reactor Trip Due to Loss of Off Site Power ENS 408142004-06-14T14:44:00014 June 2004 14:44:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Alert Declared - Reactor Trip Due to Loss of Off Site Power ENS 403492003-11-22T05:53:00022 November 2003 05:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of the "a" Emergency Diesel Generator During Testing 2024-03-24T23:34:00 | |