ENS 52010
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ENS Event | |
|---|---|
15:37 Jun 16, 2016 | |
| Title | Unanalyzed Condition of Emergency Diesel Generator During Tornado Low Pressure |
| Event Description | Upon review of recent industry operating experience, an issue was identified for the potential impact of the low barometric pressure associated with a tornado on the Emergency Diesel Generators (EDGs). The Davis-Besse Nuclear Power Station EDGs are equipped with a crankcase positive pressure trip with a set point of approximately 1 inch of water. This crankcase pressure trip is bypassed during an emergency start signal of the EDG from the Safety Features Actuation System or from an essential bus under voltage condition. Engineering has determined that a design basis tornado could create sufficient low pressure to potentially actuate the crankcase positive pressure trip due to different vent paths between the EDG Room and the EDG crankcase. If the crankcase pressure trip occurs before the EDG starts on an emergency signal due to the tornado, the crankcase pressure trip would cause an EDG lockout condition. The EDG lockout condition would then prevent either normal or emergency start of the EDG until operators could manually reset the lockout condition locally at the EDG. This condition could potentially affect both EDGs simultaneously.
No severe weather warnings or watches are forecast in the local areas that could challenge the crankcase pressure trip. Compensatory measures are being established that upon notification of a Tornado Watch or Tornado Warning that would be implemented to defeat the crankcase pressure trip function and allow the EDGs to perform their required safety function during a potential tornado. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Davis Besse  Ohio (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000346/LER-2016-006 |
| Time - Person (Reporting Time:+-0.63 h-0.0263 days <br />-0.00375 weeks <br />-8.62974e-4 months <br />) | |
| Opened: | Tom Cobbledick 14:59 Jun 16, 2016 |
| NRC Officer: | Dong Park |
| Last Updated: | Jun 16, 2016 |
| 52010 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 573732024-10-10T14:45:00010 October 2024 14:45:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 553212021-06-22T16:08:00022 June 2021 16:08:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition High-Energy Line Break Door Unable to Be Latched ENS 528652017-07-20T16:30:00020 July 2017 16:30:00 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 Potential Tornado Missile Vulnerabilities ENS 520102016-06-16T15:37:00016 June 2016 15:37:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition of Emergency Diesel Generator During Tornado Low Pressure ENS 506392014-11-25T17:00:00025 November 2014 17:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Non-Conservatisms in Methodology Used for Emergency Core Cooling System Performance Requirements ENS 498282014-02-14T08:25:00014 February 2014 08:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Shield Building Construction Opening ENS 470962011-07-26T20:00:00026 July 2011 20:00:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 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 Conditions Involving the Safety Related Direct Current (Dc) System ENS 416982005-05-13T20:00:00013 May 2005 20:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Electrical Containment Penetration ENS 404572004-01-19T16:20:00019 January 2004 16:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Certain Plant Doors May Not Be Able to Withstand Pressure Created by Main Steam Line Break ENS 402562003-10-17T13:00:00017 October 2003 13:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Steam and Feedwater Rupture Control System Unanalyzed Condition at Davis Besse 2024-10-10T14:45:00 | |
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