ENS 51487
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ENS Event | |
|---|---|
18:50 Oct 21, 2015 | |
| Title | Unanalyzed Condition Due to Pressurizer Heater Bank Potential Circuit Failure Vulnerability |
| Event Description | The isolation function when transferring control from the Main Control Room to the Alternate Shutdown Panel (AI-185) for Pressurizer Heater Bank No. 4 (including Groups No. 10, No. 11, and No. 12) has been identified as a potential circuit failure.
Identification of the potential circuit failure vulnerability is for Pressurizer Heater Bank No. 4 when isolated from Alternate Shutdown Panel (AI-185) and operated locally from Motor Control Center (MCC-4C1) for Alternate Shutdown Fire Areas 41 (Cable Spreading Room) and 42 (Main Control Room). The vulnerability involves an external hot short affecting the conductor connecting to the control room switch which may keep the 94/10 relay energized and defeat MCC control of the heaters. In a postulated event, a fire in the control room could prevent the heaters from energizing when demanded, or cause the heaters to unintentionally energize. This condition is being reported in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. Per National Fire Protection Association (NFPA) 805, fire watch is an adequate compensatory measure. Therefore, this vulnerability has been added to the existing NFPA 805 Fire Protection compensatory measure for Fire Area 41. For Fire Area 42, the Main Control Room is continuously staffed, which has been credited as the compensatory measure. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000285/LER-2015-006 |
| Time - Person (Reporting Time:+-0.28 h-0.0117 days <br />-0.00167 weeks <br />-3.83544e-4 months <br />) | |
| Opened: | Julie Bissen 18:33 Oct 21, 2015 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Oct 21, 2015 |
| 51487 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 522012016-08-25T20:23:00025 August 2016 20:23:00
[Table view]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 Involving Potential Tornado Missile Damage ENS 519172016-05-10T16:38:00010 May 2016 16:38:00 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 Containment Cooling Water System Inoperable Due to Unanalyzed Condition ENS 514872015-10-21T18:50:00021 October 2015 18:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Pressurizer Heater Bank Potential Circuit Failure Vulnerability ENS 508002015-02-09T23:30:0009 February 2015 23:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Safety Injection Tank Level Results in an Unanalyzed Condition ENS 494782013-10-28T17:30:00028 October 2013 17:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Event Could Result in a Hot Short That Could Adversely Impact Safe Shutdown Equipment ENS 493782013-09-23T18:40:00023 September 2013 18:40:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - 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Guidance Not Adequate to Mitigate a Design Basis Flood ENS 478482011-10-06T18:44:0006 October 2011 18:44:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Waste Disposal System Class One Seismic Support Inoperable ENS 470882011-07-22T13:30:00022 July 2011 13:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Fire Supression Pumps Inoperable ENS 469652011-06-16T17:30:00016 June 2011 17:30:00 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 Additional Penetration Identified for Mitigation During Walkdown ENS 462972010-09-30T21:16:00030 September 2010 21:16:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Potential Flooding Via Condensate Drain Lines ENS 458282010-04-08T21:22:0008 April 2010 21:22:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Inoperable Steam Generator Inlet Isolation Valve ENS 454672009-10-26T15:50:00026 October 2009 15:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Pressurizer and Feedwater Storage Tank Level Indications Do Not Meet Appendix R Requirements ENS 429432006-10-28T22:09:00028 October 2006 22:09:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 429022006-10-12T22:30:00012 October 2006 22:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Steam Generator Instrumentation Nonconformance ENS 428962006-10-10T20:00:00010 October 2006 20:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Containment Spray Valve Mispositioned 2016-08-25T20:23:00 | |
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