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| Entered date | Event description | |
|---|---|---|
| ENS 49543 | 16 November 2013 17:53:00 | At 10:19:02 (CST) on November 16, 2013, indication was received in the Control Room that two Secondary Containment doors, in one access opening, were open simultaneously. The interlock mechanism preventing both doors from operating simultaneously did not operate as expected. A worker was staged in the interlock to operate the doors as an interim action while a modification to prevent additional failures was being developed. The worker reported that while opening the reactor building side door the Turbine Building side door opened several inches. Both doors were immediately closed and the interlock was removed from use. Secondary Containment differential pressure remained within Technical Specification required values during the short time both doors were open. This condition represents a failure to meet Surveillance Requirement 3.6.4.1.2. As a result, entry into Technical Specification 3.6.4.1 Condition A was made momentarily due to Secondary Containment being inoperable. The doors were secured at 10:19:07 (CST) and Secondary Containment was declared Operable. This event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(C) as a condition that could have prevented the fulfillment of the safety function. The NRC Resident Inspector has been notified. |
| ENS 47370 | 24 October 2011 17:24:00 | On 10/24/11 at 1035 CDT, a maintenance technician performing a field walk-down of a clearance order inadvertently opened the bus potential fuse drawer for Unit 2 Safety Related Bus 23. This caused all loads of Bus 23 to receive an undervoltage (UV) load shed signal. Division I Containment Cooling Service Water (CCSW) pumps are powered from Bus 23 and are currently aligned to the Main Control Room Emergency Ventilation (CREV) Air Conditioning system. On a loss of CCSW, the CREV Air Conditioning system is inoperable due to a loss of its emergency cooling water supply. This condition affects both Dresden Units 2 and 3. This condition lasted for approximately 7 seconds before the bus potential fuse drawer was reinserted and the Bus 23 UV condition cleared. This event is reportable under 10CFR50.72(b)(3)(v)(D) as an event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. The licensee notified the NRC Resident Inspector. |