ENS 47919
ENS Event | |
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20:03 May 11, 2012 | |
Title | Loss of Control Room Floor Cooling |
Event Description | At 16:03 hours on 5/11/12, Susquehanna Steam Electric Station Unit 2 entered LCO 3.0.3 due to two control room floor cooling systems being inoperable.
A discharge damper for the 'A' train of control room floor cooling had failed earlier during the same day at 05:23 hours, rendering the associated 'A' fan inoperable. The redundant 'B' train fans and associated Control Structure Chiller automatically started as a result of a fan low flow interlock. The 'A' train logic was left in 'Start' and the 'B' train logic was left in 'Auto' as directed by an alarm response procedure. During application of a clearance order for repair of the failed 'A' fan damper, the 'A' control room cooling fan switch was placed in 'Stop' position. This resulted in an automatic start of the 'A' Control Structure Chiller and all the associated 'A' fans except for the control room cooling fan, and a trip of the 'B' train fans and chiller. This condition caused a loss of both control room cooling fans. The control room operators immediately recognized the loss of cooling and took manual action to restart the 'B' train. LCO 3.0.3 was exited at 16:18 hours without a reactor power reduction. This condition is reportable as loss of entire safety function under 10CFR50.72(b)(3)(v) & (vi). The licensee has notified the NRC Resident Inspector. |
Where | |
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Susquehanna ![]() Pennsylvania (NRC Region 1) | |
Reporting | |
10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
LER: | 05000388/LER-2012-001 |
Time - Person (Reporting Time:+1.4 h0.0583 days <br />0.00833 weeks <br />0.00192 months <br />) | |
Opened: | Ron Fry 21:27 May 11, 2012 |
NRC Officer: | Dong Park |
Last Updated: | May 11, 2012 |
47919 - NRC Website
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Unit 2 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |