ENS 52452
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ENS Event | |
|---|---|
17:20 Dec 21, 2016 | |
| Title | Unanalyzed Condition - 480V Bus Voltage Lower than Analyzed |
| Event Description | On October 8, 2016, it was initially discovered that the voltage tap changer settings for the 480V Shutdown Board Transformers 1-XFA-231-TS1A (TS1A) and 1-XFA-231-TS1B (TS1B) were incorrect (4160/480V instead of 3952/480V). This could potentially result in lower than minimum required voltages at the electrically downstream buses and equipment during a postulated loss of coolant accident coincident with design minimum voltage conditions. An initial Licensee Event Report (LER 50-259/2016-004-00) was submitted on December 7, 2016 following the initial review. This LER identified that a supplement would be required pending additional technical evaluation. While comprehensive analysis is not complete, the initial aggregate dynamic loading evaluation does not provide assurance that sufficient voltage would be available for various loading scenarios during postulated accident conditions. This condition was determined to have existed since a Unit 1 Design Change was implemented in 2004.
This notification is being made pursuant to 10 CFR 50.72(b)(3)(ii), as any event or condition that resulted in the nuclear plant being in an unanalyzed condition that significantly degrades plant safety. On October 9, 2016, and October 12, 2016. the transformer taps for TS1B and TS1A, respectively, were set in accordance with the applicable drawing, which specify the correct tap settings. The NRC Resident Inspector has been notified. In October 2016, the licensee validated that this problem did not exist on units two and three. |
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-0.42 h-0.0175 days <br />-0.0025 weeks <br />-5.75316e-4 months <br />) | |
| Opened: | David Renn 16:55 Dec 21, 2016 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Dec 21, 2016 |
| 52452 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 542662019-09-11T00:34:00011 September 2019 00:34:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Lightning Strike ENS 533002018-03-29T18:44:00029 March 2018 18:44:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Inoperability of Emergency Equipment Cooling Water Pump ENS 532672018-03-16T05:00:00016 March 2018 05:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Affecting Residual Heat Removal System ENS 530492017-11-01T19:25:0001 November 2017 19:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Design Deficiencies Identified During Engineering Review ENS 527072017-04-25T21:30:00025 April 2017 21:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Engineering Re-Evaluation of Tornado Impacts ENS 524522016-12-21T17:20:00021 December 2016 17:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - 480V Bus Voltage Lower than Analyzed ENS 521502016-08-03T18:00:0003 August 2016 18:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Based on Review of National Fire Protection Association Requirements ENS 499542014-03-24T19:12:00024 March 2014 19:12:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Postulated Fire-Induced Short ENS 498662014-03-02T22:30:0002 March 2014 22:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Discovered a Postulated Hot Short of a Cable During Extent of Condition Review ENS 496392013-12-16T23:00:00016 December 2013 23:00:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Potential for Spurious Start of Various Pumps During Postulated Fire Events ENS 494062013-10-03T20:35:0003 October 2013 20:35:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Inadequate Shift Staffing to Support Implementation of Safe Shutdown Instructions ENS 484672012-10-31T17:53:00031 October 2012 17:53:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Potentially Unable to Provide Power to Safe Shutdown Equipment During Appendix R Fire ENS 484212012-10-18T18:14:00018 October 2012 18:14:00 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 Fire Protection Review Identifies a Potential Unanalyzed Condition ENS 480952012-07-11T20:20:00011 July 2012 20:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Cable Associated with 4Kv Shutdown Board Routed Incorrectly ENS 479862012-06-01T14:00:0001 June 2012 14:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Cable Routing Error Could Fail Dc Control Power to Shutdown Board in a Fire ENS 478342012-04-13T20:25:00013 April 2012 20:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Impacting Emergency Diesel Generator Loading ENS 477872012-03-29T22:00:00029 March 2012 22:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Impacting Appendix R Separation Requirements ENS 477842012-03-28T21:15:00028 March 2012 21:15:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Discovered During Nfpa 805 Transition Impacting Emergency Diesel Generator Loading ENS 476512012-02-08T19:35:0008 February 2012 19:35:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Scram Functionality May Be Degraded in a Appendix R Fire ENS 473742011-10-25T20:34:00025 October 2011 20:34:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Deficiency Identified in Transition to Performance Based Standard for Fire Protection ENS 476382010-05-11T06:00:00011 May 2010 06:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition ENS 487242009-07-28T06:00:00028 July 2009 06:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition That Could Have Resulted in an Increased Maximum Flood Level 2019-09-11T00:34:00 | |
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