ENS 44465
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ENS Event | |
|---|---|
03:25 Jul 24, 2008 | |
| Title | Invalid System Actuation Due to Loss of One Offsite Power Circuit to Safety Buses |
| Event Description | This 60-day report, as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10CFR50.73(a)(2)(iv)(A) to describe an unplanned, invalid actuation of specified systems, specifically the Units 2 and 3 Primary Containment Isolation Systems (PCIS). On 7/23/08, at approximately 2325 hours0.0269 days <br />0.646 hours <br />0.00384 weeks <br />8.846625e-4 months <br />, Units 2 and 3 experienced invalid Primary Containment Isolation System (PCIS) partial isolations. Unit 2 experienced an outboard PCIS Group II isolation, while Unit 3 experienced inboard and outboard PCIS Group II isolations. The isolations involved various process lines including Reactor Water Cleanup (RWCU), Containment Atmospheric Control (CAC) / Containment Atmospheric Dilution (CAD), Drywell Sumps, and Containment Instrument Nitrogen. The Units 2 and 3 PCIS isolations were reset by approximately 2350 hours0.0272 days <br />0.653 hours <br />0.00389 weeks <br />8.94175e-4 months <br /> in accordance with procedures. All required isolation valves operated as designed.
The invalid PCIS isolations were a result of a fast transfer on associated 4 kV safety-related electrical buses for Units 2 and 3 caused by a loss of one of the two off-site power circuits that supply the 4 kV buses. This fast transfer resulted in a momentary voltage transient on electrical power supplies to the logic for the Units 2 and 3 PCIS. The two station off-site power circuits are fed from three offsite sources. The loss of the offsite power circuit was caused by failure of the 'A' phase of the '#1' transformer, which is associated with one of the three offsite power sources. This transformer is located at the North Substation. The transformer automatically isolated as a result of a fire associated with this transformer and resulted in the loss of two of the three offsite power sources. Subsequent to fire extinguishment, appropriate electrical switching was performed and the offsite power circuit was returned to an operable status by 0650 hours0.00752 days <br />0.181 hours <br />0.00107 weeks <br />2.47325e-4 months <br /> on 7/24/08. This issue has been entered into the site Corrective Action Program (CR 799684, 811332) for evaluation and implementation of further corrective actions including determining why two offsite sources were lost as a result of the transformer failure. The NRC resident has been informed of this notification. |
| Where | |
|---|---|
Peach Bottom  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1037.33 h43.222 days <br />6.175 weeks <br />1.421 months <br />) | |
| Opened: | Dave Foss 08:45 Sep 5, 2008 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Sep 5, 2008 |
| 44465 - NRC Website
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Unit 2 | |
|---|---|
| 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 562802022-11-12T04:33:00012 November 2022 04:33:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-DAY Telephonic Notification ENS 548202020-06-08T08:24:0008 June 2020 08:24:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation ENS 529612017-07-14T18:53:00014 July 2017 18:53:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Containment Isolation Valves ENS 519622016-03-28T17:20:00028 March 2016 17:20:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation ENS 500892014-03-09T21:13:0009 March 2014 21:13:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Actuation of an Emergency Service Water System ENS 479072012-03-13T20:04:00013 March 2012 20:04:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Report - Invalid Primary Containment Isolation System Actuation ENS 449402009-03-02T15:55:0002 March 2009 15:55:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation Signal Due to Maintenance Error ENS 444652008-07-24T03:25:00024 July 2008 03:25:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation Due to Loss of One Offsite Power Circuit to Safety Buses ENS 439102007-12-11T21:45:00011 December 2007 21:45:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Notification of an Invalid Actuation of Units 2 and 3 Primary Containment Isolation Systems ENS 411932004-09-28T06:00:00028 September 2004 06:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation Due to Bus Voltage Dip During Recirc Mg Start ENS 411922004-09-18T08:57:00018 September 2004 08:57:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation Due to Off Site Power Source Fast Transfer ENS 408192004-04-25T05:05:00025 April 2004 05:05:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation ENS 401982003-09-25T04:00:00025 September 2003 04:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.73(a)(1), Submit an LER Initiation of a Technical Specification Required Shutdown at Peach Bottom 2 ENS 401042003-07-27T22:39:00027 July 2003 22:39:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Report 2022-11-12T04:33:00 | |
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