ENS 47510
ENS Event | |
|---|---|
11:00 Dec 8, 2011 | |
| Title | Unanalyzed Condition - Non Fused Dc Bus Ammeters Could Short and Cause a Fire |
| Event Description | During Operating Experience (OPEX) review of Browns Ferry Fire Protection ENS 47374, 'Deficiency Identified in Transition to Performance Based Standard for Fire Protection,' a similar condition was identified at Clinton Power Station.
During site review, it was determined that original plant wiring design for the station battery ammeter contains a 'shunt' in the current flow from each direct current (DC) battery. Bolted on the shunt bar are two IEEE 383 qualified leads to a current meter in the main control room (MCR). The small difference in voltage between the two taps on the shunt is enough to deflect the current gauge in the MCR when current flows from the battery through the shunt. The ammeter wiring attached to the shunt does not have fuses, and if one of these ammeter wires shorts to ground at the same time another DC wire from the opposite polarity on the same battery also shorts to ground, a ground loop through the unfused ammeter cable could occur. With enough current going through the cable, the potential exists that a fire in the raceway system or MCR could occur wherever the cable is routed. This design condition exists in Divisions 1, 2, 3, and 4. This condition is reportable in accordance with 10CFR50.72(b)(3)(ii)(B), 'Any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety.' Compensatory fire watch measures have been implemented for affected areas of the plant. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Clinton  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+2.5 h0.104 days <br />0.0149 weeks <br />0.00342 months <br />) | |
| Opened: | Ed Tiedenmann 13:30 Dec 8, 2011 |
| NRC Officer: | John Shoemaker |
| Last Updated: | Dec 8, 2011 |
| 47510 - NRC Website
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WEEKMONTHYEARENS 531102017-12-09T19:48:0009 December 2017 19:48:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Manual Reactor Scram Due to Loss of Division 1 Ac Power to Numerous Components ENS 526012017-03-09T09:19:0009 March 2017 09:19:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Relay Failure ENS 523772016-11-17T23:00:00017 November 2016 23:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Incorrect Method Used for Calculation of Control Room Habitability ENS 516692016-01-20T19:11:00020 January 2016 19:11:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Primary-Secondary Containment Pressure Differential Exceeded Due to Ccp Exhaust Fan Trip ENS 493732013-09-20T14:17:00020 September 2013 14:17:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Safe Shutdown Analysis Reveals Noncompliance for a Fire Outside Diesel Room ENS 475102011-12-08T11:00:0008 December 2011 11:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Non Fused Dc Bus Ammeters Could Short and Cause a Fire ENS 466032011-02-08T14:00:0008 February 2011 14:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Event Could Initiate High Pressure Core Spray and Overfill the Reactor Pressure Vessel ENS 451222009-06-10T14:20:00010 June 2009 14:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Unknown Cable with Combustible Coating Found in Division I / Division II Cable Tray 2017-03-09T09:19:00 | |