ENS 46917
ENS Event | |
|---|---|
04:39 Jun 3, 2011 | |
| Title | Unexpected Emergency Diesel Generator Actuation |
| Event Description | On 6/3/2011 at 0039 hours4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br />, during the performance of a work order to test components associated with Service Water Isolation, Emergency Diesel Generator (EDG) 'A' unexpectedly started automatically and its supply breaker to Safeguards Bus 14 closed. The Control Room staff observed normal voltage on Diesel Generator 'A'. Bus 14 voltage was never lost during this event, however, they also noted an associated Bus 14 undervoltage annunciator on the Main Control Board. Seconds later, Emergency Diesel Generator 'A' tripped on Reverse Power and its supply breaker to Bus 14 tripped open. The initiating action was the removal of the Bus 14 Normal Feed Breaker Control Power Fuses as part of the work order package.
The Ginna EDG's have the following automatic start signals and logic: manual, safety injection signal (1/2 trains), undervoltage on respective safeguards bus, 'A' EDG Bus 14 or 18 (1 out of 2 degraded voltage + 1 out of 2 loss of voltage), 'B' EDG Bus 16 or 17 (1 out of 2 degraded voltage + 1 out of 2 loss of voltage). Investigation has commenced to determine the cause of the EDG start and undervoltage signal. The NRC Resident Inspector has been notified.
The purpose of this report is to retract the event discussed in Emergency Notification System report #46917 submitted on June 3rd, 2011. The ENS notification reported an unexpected start of Emergency Diesel Generator `A' during testing of a service water valve isolation circuit. As reported, Emergency Diesel Generator 'A' unexpectedly started and its supply breaker to Bus 14 closed. Seconds later, the Emergency Diesel Generator tripped on reverse power and its output breaker to Bus 14 opened. At the time of the event it was not understood why the diesel generator started. Subsequent troubleshooting and causal investigation identified that the signal was caused by a degraded control relay that unexpectedly changed state when control power was removed. This relay was expected to remain mechanically latched and would have remained in the desired position had control power not been removed as part of the test. Bus 14 voltage remained in the normal operating range throughout the event. Since this was not a valid undervoltage signal, the June 3rd, 2011 event is being retracted. A follow-up report will be made in accordance with 10CFR50.73(a)(1) and 10CFR50.73(a)(2)(iv). The NRC Resident Inspector has been notified. R1DO(Henderson) notified. See related EN #47094. |
| Where | |
|---|---|
Ginna  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+1.25 h0.0521 days <br />0.00744 weeks <br />0.00171 months <br />) | |
| Opened: | Craig Jones 05:54 Jun 3, 2011 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jul 26, 2011 |
| 46917 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 567902023-10-13T01:27:00013 October 2023 01:27:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 567312023-09-09T15:43:0009 September 2023 15:43:00 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 555042021-10-04T04:31:0004 October 2021 04:31:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid System Actuation ENS 536962018-10-26T04:00:00026 October 2018 04:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Automatic Start of the Emergency Diesel Generator and Loss of Radiation Monitor ENS 517302016-02-12T04:05:00012 February 2016 04:05:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Auto-Started Due to the Loss of a Station Service Transformer ENS 492142013-07-24T18:19:00024 July 2013 18:19:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip from Full Power ENS 479882012-06-03T06:39:0003 June 2012 06:39:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Autostart of "B" Edg Due to Loss of Offsite Power Circuit 767 ENS 473382011-10-12T03:28:00012 October 2011 03:28:00 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 Auto Stop Valve Closure ENS 469172011-06-03T04:39:0003 June 2011 04:39:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unexpected Emergency Diesel Generator Actuation ENS 432432007-03-17T02:09:00017 March 2007 02:09:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Caused by Safety Injection Signal ENS 431282007-01-28T01:40:00028 January 2007 01:40:00 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 Load Transient Caused by Ehc Problem ENS 417652005-06-10T17:51:00010 June 2005 17:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Offsite Bus Due to a Lighting Strike with Actuation of Emergency Diesel Generator ENS 415582005-04-01T19:02:0001 April 2005 19:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Start Due to a Partial Loss of Offsite Power ENS 414142005-02-17T02:12:00017 February 2005 02:12:00 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 Turbine Trip as a Result of Failed Power Supply ENS 403192003-11-13T14:54:00013 November 2003 14:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Auto Start and Loading of the "B" Emergency Diesel Generator ENS 402482003-10-15T14:24:00015 October 2003 14:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation a Manual Reactor Trip from 1% Power as Per Abnormal Operating Procedures Occurred 2023-09-09T15:43:00 | |