ENS 41847
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ENS Event | |
|---|---|
02:31 Jul 18, 2005 | |
| Title | Unanalyzed Condition of Maintenance Bus Tie Breakers |
| Event Description | During review of 10CFR50 Appendix R, III.G.2 compliance, it was discovered that a fire in a divisional switchgear room affecting maintenance tie breakers 64T or 65T, may result in the opposite division diesels [tripping]. The postulated fire could affect cables associated with a maintenance tie breaker which could in turn cause associated bus tie breakers in the opposite division to close (B9, C9, E9, F9). The III.G.2 scenario would also include a Loss of Offsite Power event which would require the [Emergency Diesel Generators] (EDG's) to be running. Postulating multiple hot shorts could result in both 9 breakers in a single division closing and paralleling the EDG's out of synch resulting in potential damage to the EDG's.
Compensatory action: Eliminated this failure mechanism by racking out the four tie breakers (B9, C9, E9, F9) that could be affected. This does not affect operability of the EDG's. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Fermi  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000341/LER-2005-006 |
| Time - Person (Reporting Time:+-2.22 h-0.0925 days <br />-0.0132 weeks <br />-0.00304 months <br />) | |
| Opened: | Derek Drockelman 00:18 Jul 18, 2005 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Jul 18, 2005 |
| 41847 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (74 %) |
| After | Power Operation (74 %) |
WEEKMONTHYEARENS 552312021-05-03T13:30:0003 May 2021 13:30:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 537122018-11-01T04:00:0001 November 2018 04:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition En Revision Imported Date 12/31/2018 ENS 536742018-10-19T04:00:00019 October 2018 04:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Low Pressure Core Injection Pumps Incapable of Automatic Startup ENS 527242017-05-02T21:00:0002 May 2017 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition for Combustion Turbine Generator Configuration ENS 523422016-11-02T14:34:0002 November 2016 14:34:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition for Control Rod Drop Accident at Low Power ENS 522142016-08-31T23:50:00031 August 2016 23:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition with a Potential Tornado ENS 522022016-08-25T20:29:00025 August 2016 20:29:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Mechanical Draft Cooling Tower Declared Inoperable ENS 514402015-10-02T12:25:0002 October 2015 12:25:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Loose Safety Relief Valve Discharge Flange Bolts ENS 422242005-12-23T03:25:00023 December 2005 03:25:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Eecw Temperature Control Valve Not Fully Open ENS 418472005-07-18T02:31:00018 July 2005 02:31:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition of Maintenance Bus Tie Breakers ENS 418162005-06-30T23:31:00030 June 2005 23:31:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Related to the Standby Feedwater Pumps and Control Circuits ENS 417142005-05-18T22:50:00018 May 2005 22:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Identification of Design and Operating Procedure Deficiencies Related to Appendix R Events ENS 415512005-03-30T21:00:00030 March 2005 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Identification of Design and Operating Procedure Deficiencies 2021-05-03T13:30:00 | |
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