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| Entered date | Event description | |
|---|---|---|
| ENS 47084 | 21 July 2011 16:45:00 | On July 21, 2011 at 1100 (CDT) Callaway Plant staff determined that a design deficiency could adversely affect the 'B' Train of Essential Service Water (ESW) in the event of a Control Room fire. 'B' Train is the credited train for completion of a post-fire safe shutdown as a result of a Control Room evacuation. As a result of this deficiency, normally closed valve EFHV0060 could spuriously open during a postulated control room fire. EFHV0060 is located on the ESW return line from the 'B' Component Cooling Water (CCW) heat exchanger. If EFHV0060 spuriously opened as a result of this postulated fire, the flow balance in the 'B' Train of the ESW system would be affected. In this scenario, cooling water flow to other essential components could be reduced to below the minimum requirements. A fire watch has been imposed as a compensatory measure for this condition. Additionally, EFHV0060 has been closed and de-energized to preclude spurious opening in the event of a postulated control room fire. This condition is reported in accordance with 10 CFR 50.72 (b)(3)(ii)(B) as an unanalyzed condition that significantly degrades plant safety. The NRC Resident Inspector has been notified. |