ENS 45282

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v t e ENS Event
14:52 Aug 21, 2009
Title	Logic for Common Accident Signal Is Flawed for Safe Shutdown Instruction
Event Description	Safe Shutdown Instruction (SSI) 0-SSI-9 for an Appendix R fire event requires for a Unit 1 Safe Shutdown success path that 4kV Shutdown Board A be supplied by Diesel Generator 3A via 4kV Shutdown Board 3EA. During a Unit 2 simulator exercise utilizing this SSI, reactor vessel water level lowered to Level 1 (-122 inches) causing a Common Accident Signal (CAS) trip of 4 Kv Shutdown Board 3EA inter-tie breaker (1844) that de-energized 4kV Shutdown Board A. This condition will not support the Unit 1 success path for alternate decay heat removal during an Appendix R fire. The 4 Kv Shutdown Board A must be re-energized by closing breaker 1844. For this SSI (0-SSI-9) the subsequent automatic start of the 2A RHR and Core Spray pumps in response to the CAS logic has not been considered in the development of the SSIs. In response to this condition, compensatory measures have been implemented to provide equivalent shutdown capability, documented on Fire Protection Impairment Permit (FPIP) 09-1920. This event is reportable within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> under 10CFR50.72 (b)(3)(v)(A) - Any event or condition that results in the condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: Shut down the reactor and maintain it in a safe shutdown condition. This event is also a reportable within 60 days under 10CFR50.73(a)(2)(v)(A) - Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to: Shut down the reactor and maintain it in a safe shutdown condition. This condition has been documented in the BFN Corrective Action program as PER# 177130. Unit 1, 2 and 3 remain at 100% power and are not affected by this event. The NRC Resident Inspector has been notified.

ENS 45282 +/-
Where
Browns Ferry Alabama (NRC Region 2)
Reporting

10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor
Time - Person (Reporting Time:+0.17 h0.00708 days <br />0.00101 weeks <br />2.32866e-4 months <br />)
Opened:	William Baker 15:02 Aug 21, 2009
NRC Officer:	John Knoke
Last Updated:	Aug 21, 2009
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v • d • e

v t e Emergency Notification System
Browns Ferry with 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor
WEEKMONTHYEAR2022-10-18T19:40:00 [Table view]
[ENS list for Browns Ferry]

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