ENS 52601
ENS Event | |
|---|---|
09:19 Mar 9, 2017 | |
| Title | Unanalyzed Condition Due to Relay Failure |
| Event Description | On March 7, 2017, Division 2 Residual Heat Removal (RHR) system was inoperable due to a scheduled maintenance system outage window. At 2258 [CST], Operations identified a Division 1 Unit Substation Switchgear relay was cycling, which is part of the Division 1 AC Power system. The specific relay could not be identified at the time. Division 1 AC Power systems were protected.
On March 8, 2017 at 1830 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br />, Division 2 RHR was restored to operable status. On March 9, 2017 at 0319 hours0.00369 days <br />0.0886 hours <br />5.274471e-4 weeks <br />1.213795e-4 months <br />, Operations declared Division 1 Emergency Diesel Generator (EDG) inoperable due to the [identification of the] Division 1 relay as related to properly tripping non-essential loads on a bus under-voltage condition. The relay would not have actuated to trip non-essential loads. The proper tripping of non-essential loads is a requirement for Division 1 EDG. The Updated Safety Analysis Report (USAR) Emergency Core Cooling Systems (ECCS) analysis specifies with the Division 1 DG failure, the remaining systems available are: Automatic Depressurization System (ADS), High Pressure Core Spray (HPCS), and 2 Low Pressure Core Injection (LPCI) systems. As a result of Division 2 RHR [being] inoperable at the same time Division 1 EDG was inoperable, an unanalyzed condition existed. While Division 2 RHR was inoperable, Division 1 EDG was inoperable. Technical Specification (TS) Limiting Condition of Operation (LCO) 3.8.1, AC Sources - Operating, was not met. Condition B, One Required DG Inoperable, Required Action B.2 declares required features, [normally] supported by the inoperable DG, inoperable when the redundant required features are inoperable, with a completion time of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The action would have required declaring Division 1 ECCS inoperable, which includes Division 1 RHR and Low Pressure Core Spray (LPCS). With Division 1 EDG, Division 1 RHR, and Division 2 RHR inoperable, the station did not satisfy the USAR ECCS analysis and was in an unanalyzed condition. This condition is reportable under 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, since the condition occurred within three years of the date of discovery. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Clinton  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+1.63 h0.0679 days <br />0.0097 weeks <br />0.00223 months <br />) | |
| Opened: | Luke Echols 10:57 Mar 9, 2017 |
| NRC Officer: | Bethany Cecere |
| Last Updated: | Mar 9, 2017 |
| 52601 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (99 %) |
| After | Power Operation (99 %) |
WEEKMONTHYEARENS 531102017-12-09T19:48:0009 December 2017 19:48:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 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, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Manual Reactor Scram Due to Loss of Division 1 Ac Power to Numerous Components ENS 526012017-03-09T09:19:0009 March 2017 09:19:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Relay Failure ENS 523772016-11-17T23:00:00017 November 2016 23:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Incorrect Method Used for Calculation of Control Room Habitability ENS 516692016-01-20T19:11:00020 January 2016 19:11:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Primary-Secondary Containment Pressure Differential Exceeded Due to Ccp Exhaust Fan Trip ENS 493732013-09-20T14:17:00020 September 2013 14:17:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Safe Shutdown Analysis Reveals Noncompliance for a Fire Outside Diesel Room ENS 475102011-12-08T11:00:0008 December 2011 11:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Non Fused Dc Bus Ammeters Could Short and Cause a Fire ENS 466032011-02-08T14:00:0008 February 2011 14:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Event Could Initiate High Pressure Core Spray and Overfill the Reactor Pressure Vessel ENS 451222009-06-10T14:20:00010 June 2009 14:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Unknown Cable with Combustible Coating Found in Division I / Division II Cable Tray 2017-03-09T09:19:00 | |