ENS 47370: Difference between revisions
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| event date = 10/24/2011 10:35 CDT | | event date = 10/24/2011 10:35 CDT | ||
| last update date = 10/24/2011 | | last update date = 10/24/2011 | ||
| title = Accident Mitigation Systems Out | | title = Accident Mitigation Systems Out of Service Due to Maintenance Error | ||
| event text = 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. | | event text = 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. | 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. | ||
Latest revision as of 21:05, 1 March 2018
| Where | |
|---|---|
Dresden  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+1.82 h0.0758 days <br />0.0108 weeks <br />0.00249 months <br />) | |
| Opened: | Amy Mcmartin 17:24 Oct 24, 2011 |
| NRC Officer: | Vince Klco |
| Last Updated: | Oct 24, 2011 |
| 47370 - NRC Website
| |
Dresden with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |