ENS 47094
ENS Event | |
|---|---|
04:39 Jun 3, 2011 | |
| Title | Invalid Actuation of Emergency Diesel Generator |
| Event Description | This report is being made per paragraphs 50.73(a)(1) and 50.73(a)(2)(iv)(A) to address an actuation of Emergency Diesel Generator 'A' on June 3rd, 2011 while performing service water valve isolation signal testing. Emergency AC Electrical power system, including emergency diesel generators, is a system named in 50.73(a)(2)(iv)(B).
During a refueling outage, testing was in progress to verify that service water isolation valves received the proper close signal during a safety injection. The test configuration required pulling control power fuses for the Bus 14 normal supply breaker to prevent operation and allow for manual relay actuation. Within seconds of pulling these fuses, the control room received a Bus 14 undervoltage annunciator, Emergency Diesel Generator 'A' started, and the generator output breaker closed onto Bus 14. Upon further investigation, the cause of this signal was identified as a degraded control relay that failed to mechanically latch and unexpectedly changed state when control power was removed. This resulted in an invalid undervoltage signal. Bus voltage remained within normal operating range. Given that the diesel generator was in unit mode of operation and was not fully synchronized with the normal bus supply, the diesel generator tripped shortly after starting due to a valid reverse power signal. A field verification and technical review was performed to ensure that this condition did not cause significant stress on the generator or engine. This start signal is considered an INVALID signal with respect to 50.73(a)(2)(iv)(A), however the system was not fully removed from service. The 'B' train was not affected by this event. The actuation was considered complete since all necessary components responded to the undervoltage signal as expected under the actual field conditions. The control relay would have remained in the desired position and performed its required function under design conditions with normal control power available. Therefore the degradation was not determined to have an impact on the safety function. The NRC Resident Inspector was notified. See related EN #46917. |
| Where | |
|---|---|
Ginna  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1279.58 h53.316 days <br />7.617 weeks <br />1.753 months <br />) | |
| Opened: | Mike Slaby 12:14 Jul 26, 2011 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jul 26, 2011 |
| 47094 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 556092021-10-17T18:58:00017 October 2021 18:58:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Telephonic Notification for Invalid Specified Actuation of Containment Isolation Train ENS 516042015-10-21T05:29:00021 October 2015 05:29:00 10 CFR 50.73(a)(1), Submit an LER Diesel Generator Start Due to Invalid Signal ENS 502312014-05-08T17:20:0008 May 2014 17:20:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephonic Notification of Invalid Specified System Actuation ENS 470942011-06-03T04:39:0003 June 2011 04:39:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Emergency Diesel Generator ENS 469662011-04-25T01:44:00025 April 2011 01:44:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Notification of Invalid Start of Emergency Diesel Generator. ENS 466242010-12-29T05:00:00029 December 2010 05:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation Due to Operator Error ENS 443202008-05-10T01:32:00010 May 2008 01:32:00 10 CFR 50.73(a)(1), Submit an LER Invalid Auxiliary Feedwater System Actuation ENS 403322003-10-08T07:16:0008 October 2003 07:16:00 10 CFR 50.73(a)(1), Submit an LER Invalid Safety Injection Signal During Surveillance Testing at Ginna ENS 403312003-09-27T20:44:00027 September 2003 20:44:00 10 CFR 50.73(a)(1), Submit an LER Invalid Partial Safety Injection Signal During Surveillance Testing at Ginna 2021-10-17T18:58:00 | |