ENS 52865
ENS Event | |
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16:30 Jul 20, 2017 | |
Title | Potential Tornado Missile Vulnerabilities |
Event Description | In order to address the concerns outlined in RIS 2015-06 'TORNADO MISSILE PROTECTION,' an evaluation of tornado missile vulnerabilities and their potential impact on Technical Specification (TS) plant equipment was conducted. This evaluation concluded that the following Structures, Systems, and Components (SSCs) are potentially vulnerable to tornado generated missiles:
The Davis-Besse Nuclear Power Station (DBNPS) Unit 1 Emergency Diesel Generator (EDG) Fuel Oil Storage Tanks (FOST) (DB-Tl53-l, DB-T-153-2) support the EDG operation for 7 days. The vents on the FOST are necessary to support the transfer of fuel from the FOST to the EDG day tank. These vents are not protected and are vulnerable to a potential tornado-generated missile impact. This postulated strike could impact fuel transfer to the EDG day tank and, therefore does not support operability of both EDGs for Technical Specification 3.8.1. Tornado generated missiles striking the FOST vent piping could potentially affect pump performance and challenge the structural integrity of the tank. This would render both the FOST and corresponding EDG inoperable. This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) and 10 CFR 50.72(b)(3)(v)(A). The potential vulnerabilities for the FOST vents (as discussed above) are being addressed in accordance with NRC EGM-15-002 Revision 1 and DSS-ISG-2016-01 NRC enforcement discretion and interim guidance documents. Immediate compensatory measures were taken to mitigate the potential consequences of an onsite tornado generated missile impact on the FOST vents. The licensee notified the NRC Resident Inspector. |
Where | |
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Davis Besse Ohio (NRC Region 3) | |
Reporting | |
10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | |
LER: | 05000346/LER-2017-001 |
Time - Person (Reporting Time:+-3 h-0.125 days <br />-0.0179 weeks <br />-0.00411 months <br />) | |
Opened: | Warren Cleveland 13:30 Jul 20, 2017 |
NRC Officer: | Dan Livermore |
Last Updated: | Jul 20, 2017 |
52865 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |