ENS 55534
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ENS Event | |
|---|---|
21:46 Oct 20, 2021 | |
| Title | Valid Specified System Actuations of Unit 1 and Unit 3 Emergency Diesel Generators |
| Event Description | At 1446 MST on October 20, 2021, a start-up transformer de-energized, resulting in a loss of power to the Unit 1 Train B 4.16 kV Class 1E Bus and the Unit 3 Train A 4.16 kV Class 1E Bus. The Unit 1 Train B Emergency Diesel Generator (EDG) and Unit 3 Train A EDG automatically started and energized their respective 4.16 kV Class 1E Buses.
This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of emergency AC electrical power systems. All systems operated as expected. Per the Emergency Plan, no classification was required due to the event. Units 1 and 3 both remain in Mode 1 at 100 percent power. Unit 2 is currently in a refueling outage and defueled. The 4.16 kV Class 1E Buses in Unit 2 were not affected by the de-energization of the start-up transformer since it was not aligned as normal power for Unit 2. The cause of the start-up transformer being de-energized is under investigation. The NRC Resident Inspectors have been informed.
As a result of the Loss of Power on the Unit 1 Train B 4.16 kV Class 1E Bus, the B Auxiliary Feedwater Pump automatically started, as expected. The B Auxiliary Feedwater Pump was not needed for steam generator water level control and no auxiliary feedwater valves repositioned. The B Auxiliary Feedwater Pump did not supply feedwater to the steam generators. The NRC Resident Inspector will be notified. Notified R4DO (Taylor). |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+2.27 h0.0946 days <br />0.0135 weeks <br />0.00311 months <br />) | |
| Opened: | Stephanie Brabson 00:02 Oct 21, 2021 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Dec 3, 2021 |
| 55534 - NRC Website
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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 | |
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