ENS 54487
ENS Event | |
|---|---|
03:18 Jan 22, 2020 | |
| Title | |
| Event Description | EN Revision Imported Date : 2/21/2020
CONTAINMENT RELIEF VALVES INOPERABLE At 22:18 (EST) on 1/21/20, it was discovered that all Unit 1 containment vacuum relief isolation valves were closed and all vacuum relief lines were simultaneously inoperable; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). The isolation valves were opened and the vacuum relief valves were restored to operable. There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
At 1549 (EST), February 20, 2020, a completed engineering evaluation of the condition initially reported on January 22, 2020 determined that the inoperability of the Sequoyah Unit 1 Containment Vacuum Relief System affected the ability to protect containment against an external pressure event. This condition is not bounded by existing design and licensing documents; however, it poses no impact to the health and safety of the public or plant personnel. The condition was resolved when isolation valves were opened on January 21, 2020 and the vacuum relief lines were restored to an operable status. Therefore, this event is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(ii)(B), "an unanalyzed condition that significantly degrades plant safety. Subsequent to the initial notification, continued evaluation of the reported condition has concluded that the isolation of the containment vacuum relief function did not prevent the fulfillment of a safety function that is needed to control the release of radioactive material; nor mitigate the consequences of an accident therefore this event is not reportable under 10 CFR 50.72(b)(3)(v), "Event or Condition that could have prevented fulfillment of a safety function. The NRC Resident has been notified. Notified R2DO (Musser) |
| Where | |
|---|---|
Sequoyah  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+1.27 h0.0529 days <br />0.00756 weeks <br />0.00174 months <br />) | |
| Opened: | John Alexander 04:34 Jan 22, 2020 |
| NRC Officer: | Brian P. Smith |
| Last Updated: | Feb 20, 2020 |
| 54487 - NRC Website | |
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 | |