ENS 49818
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ENS Event | |
|---|---|
23:00 Feb 11, 2014 | |
| Title | Nonconservative Operator Manual Actions Identified in Appendix R Analysis |
| Event Description | Preliminary Westinghouse transient analysis calculations of Watts Bar Nuclear (WBN) Unit 1 fire protection features revealed that there is less time than previously credited to perform certain operator manual actions (OMA) to prevent Pressurizer (PZR) overfill during an Appendix R fire.
Specifically, an assumed Appendix R fire in rooms 713.0-A28, 737.0-A1A, 757.0-A2, 757.0-A5, 757.0-A9, 772.0-A1, 772.0-A2, or 772.0-A5 could result in spurious operation of multiple components in the normal and emergency charging flow paths. Westinghouse's analysis indicates the required time to isolate the normal charging path is approximately two minutes, securing the second charging pump is approximately four minutes and isolating the emergency charging path is approximately 12.5 minutes. Based on this preliminary analysis, WBN procedures are non-conservative since they require these actions to be completed in 18 minutes. TVA has verified that potentially impacted Appendix R equipment remains functional; however, a compensatory fire watch has been established for the above listed areas. This immediate action will ensure that the approved Appendix R Fire Safe Shutdown Plan can be achieved. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| LER: | 05000390/LER-2014-002 |
| Time - Person (Reporting Time:+-3.53 h-0.147 days <br />-0.021 weeks <br />-0.00484 months <br />) | |
| Opened: | Damon Fegley 19:28 Feb 11, 2014 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Feb 11, 2014 |
| 49818 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Watts Bar with 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 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 | |
WEEKMONTHYEARENS 571262024-05-13T13:17:00013 May 2024 13:17:00
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Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Emergency and Auxiliary Gas Treatment Systems ENS 509602015-04-06T21:00:0006 April 2015 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Volume Control Tank Isolation Time Analysis Error ENS 508872015-03-13T15:00:00013 March 2015 15:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 505962014-11-05T18:10:0005 November 2014 18:10:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Regarding Appendix R Procedures ENS 505402014-10-15T21:00:00015 October 2014 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Appendix R Unanalyzed Condition Affecting the Turbine Driven Aux Feedwater Pump ENS 502452014-07-01T02:46:0001 July 2014 02:46:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition That Could Have Resulted in an Increased Maximum Flood Level ENS 498182014-02-11T23:00:00011 February 2014 23:00:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - 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Release of Radioactive Material Temporary Loss of Both Trains of Emergency Gas Treatment System ENS 480562012-06-29T14:28:00029 June 2012 14:28:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Increase in Probable Maximum Flood Level ENS 487232009-07-28T05:00:00028 July 2009 05:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition That Could Have Resulted in an Increased Maximum Flood Level ENS 451702009-06-27T17:20:00027 June 2009 17:20:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Auxiliary Building Gas Treatment System Rendered Inoperable ENS 451102009-05-27T23:05:00027 May 2009 23:05:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Both Trains of Auxiliary Building Gas Treatment System Rendered Inoperable ENS 440852008-03-21T13:13:00021 March 2008 13:13:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident System Injection Determined Inoperable by Failure to Remove Electrical Jumper Prior to Mode Change ENS 402212003-10-03T19:16:0003 October 2003 19:16:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Accident Mitigation System Degraded Due to Both Trains of Auxiliary Building Gas Treatment System Inoperable 2024-05-13T13:17:00 | |
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