ENS 51854
ENS Event | |
|---|---|
19:07 Apr 7, 2016 | |
| Title | Unanalyzed Condition - High Pressure Fire Suppression Isolated from Containment |
| Event Description | This notification is being made as the result of the review of an occurrence on March 30, 2016 at 2220 [EDT] that resulted when a major portion of the site high pressure fire protection (HPFP) system, including fire suppression capabilities for the Main Turbine Building, Auxiliary Building, Control Building, Diesel Generator Buildings, and both Unit 1 and Unit 2 Containments were isolated without having the required compensatory suppression systems established. Upon discovery of the non-functional HPFP system, compensatory fire watches were established and an alternate means to provide water to the HPFP system was aligned.
A review of the Sequoyah Nuclear Plant (SQN) Safe Shutdown Analysis identified this loss of fire suppression may not have ensured the required equipment remained available under certain postulated fire scenarios. The analysis determined that the effects of a postulated fire in specific fire areas could have prevented critical systems or components from performing their intended functions, potentially resulting in the inability to achieve and maintain safe shutdown. Analysis identified areas which credit the availability of fire suppression to assure that the safe shutdown capability could have been achieved, the site did not have fire suppression for approximately 45 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br />. No actual fire occurred or existed during the time the fire suppression system was not functional. Installed fire detection equipment and communication to the Main Control Room remained available. The condition has been corrected and the HPFP system is functional. At the time of the non-functional HPFP system, it was not recognized that an unanalyzed condition that could have significantly degraded plant safety existed. The condition placed both Unit 1 and Unit 2 in an unanalyzed condition that significantly degraded plant safety and is reportable under 10 CFR 50.72(b)(3)(ii)(B). This 8-hour non emergency notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(B). The condition has been entered into the licensee's corrective action program (CR 1155763) and a License Event Report will be submitted. The NRC Resident Inspector has been notified of this condition. The original clearance that created this event was satisfactory as written, however, one of the valves was leaking and the clearance boundaries were expanded. The clearance was issued at 1411 EDT on 3/29/2016. |
| Where | |
|---|---|
Sequoyah  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-1.1 h-0.0458 days <br />-0.00655 weeks <br />-0.00151 months <br />) | |
| Opened: | Xavier Decambra 18:01 Apr 7, 2016 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Apr 7, 2016 |
| 51854 - 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 544872020-01-22T03:18:00022 January 2020 03:18:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition ENS 521872016-08-17T21:22:00017 August 2016 21:22:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Not Meeting Single Failure Criteria ENS 519942016-06-08T19:26:0008 June 2016 19:26:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition That Could Potentially Degrade Plant Safety ENS 519352016-05-17T01:05:00017 May 2016 01:05:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition That Significantly Degrades Plant Safety ENS 518542016-04-07T19:07:0007 April 2016 19:07:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - High Pressure Fire Suppression Isolated from Containment ENS 515272015-11-10T20:02:00010 November 2015 20:02:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 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 Unanalyzed Condition Due to Debris Dropped Into Reactor Cavity Equipment Pit ENS 502442014-07-01T02:46:0001 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 496902014-01-03T20:00:0003 January 2014 20:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Abgts Potentially Inoperable for Both Units Under Worst-Case Conditions ENS 485842012-12-13T00:14:00013 December 2012 00:14:00 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 Risk of Possible Flooding to Ercw Building During Design Basis Flood ENS 487252009-07-28T05:00:00028 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 448142009-01-28T19:25:00028 January 2009 19:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Related to a Postulated Appendix R Fire Scenario 2020-01-22T03:18:00 | |