ENS 53267
ENS Event | |
|---|---|
05:00 Mar 16, 2018 | |
| Title | Unanalyzed Condition Affecting Residual Heat Removal System |
| Event Description | At 1604 [CDT] on March 16, 2018, Browns Ferry Nuclear Plant (BFN) Engineering reported an unanalyzed condition affecting the Residual Heat Removal (RHR) heat exchangers in a postulated fire event. It was discovered that the Residual Heat Removal Service Water (RHRSW) heat exchanger piping associated [with] the credited heat exchangers in the NFPA 805 Nuclear Safety Capability Analysis (NSCA) could experience water hammer damage.
Fire damage to the cables for the RHRSW outlet motor operated valves could cause the valves to spuriously open and drain the RHRSW piping. Subsequent starting of the RHRSW pumps on the affected header could cause water hammer loads and damage the piping. Review of NFPA 805 analyses show the cables associated with this condition are routed in Fire Areas 01-03, 02-03, 02-04, 03-03, 16 and 23. There are 11 cases where the deterministically credited heat exchanger could be affected. Compensatory fire watch measures have been established. This event requires an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> report in accordance with 10CFR50.72(b)(3)(ii)(B), 'Any event or condition that results in: (B) The nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. CR 1139620 documents this condition in the Corrective Action Program. The NRC Resident Inspector has been notified.
NRC notification 53267 was made to ensure that the eight-hour non-emergency reporting requirements of 10 CFR 50.72 were met when the licensee discovered an unanalyzed condition with the potential to significantly degrade plant safety. On August 22, 2018, an independent analysis was completed which determined that the RHRSW system would remain functional during the postulated scenario. Based on this analysis, a revised functional evaluation was performed by BFN which determined that the condition did not constitute an unanalyzed condition that significantly degraded plant safety. For credited RHR heat exchangers for fire events in Fire Areas 01-03, 02-03, 02-04, 03-03, 16, and 23, the RHRSW piping will remain intact and the valves will operate manually after a water hammer event. This condition did not significantly degrade plant safety and is therefore not reportable under 10 CFR 50.72(a)(2)(ii)(B). On November 16, 2018, TVA canceled the 60 day report which had been submitted for this condition. TVA's evaluation of this event notification is documented in the corrective action program. The licensee has notified the NRC Resident Inspector. Notified the R2DO (Shaeffer). |
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+17.07 h0.711 days <br />0.102 weeks <br />0.0234 months <br />) | |
| Opened: | Drew Mitchell 22:04 Mar 16, 2018 |
| NRC Officer: | David Aird |
| Last Updated: | Nov 29, 2018 |
| 53267 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| 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 | |