ENS 49638
ENS Event | |
|---|---|
22:27 Dec 16, 2013 | |
| Title | Unanalyzed Condition Due To Unfused Direct Current Ammeter Circuits |
| Event Description | At 1627 CST on December 16, 2013 Farley Nuclear Plant determined that the following was an unanalyzed condition:
As a result of recent industry operating experience (OE 305419, EN 49411, EN 49419) regarding the impact of un-fused Direct Current (DC) ammeter circuits in the Control Room, Farley performed a review of ammeter circuitry for similar issues. The review determined the described condition to be applicable to Farley resulting in an unanalyzed condition with respect to 10 CFR 50 Appendix R analysis requirements. The wiring design for the ammeters contains a shunt in the current flow from each DC battery and battery charger, but the ammeter wiring attached to the shunt does not contain fuses. It is postulated that a fire could cause one of the ammeter wires to short to ground. Concurrently, the fire causes another DC wire from the opposite polarity on the same battery to also short to ground. This would cause a ground loop through the un-fused ammeter cable. The potential exists that the cable could heat up, causing a secondary fire in the ammeter raceway. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to safely shutdown per 10 CFR 50 Appendix R. This condition is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. Compensatory measures have been implemented for affected areas of the plant. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Farley  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-0.83 h-0.0346 days <br />-0.00494 weeks <br />-0.00114 months <br />) | |
| Opened: | Darrin Gard 21:37 Dec 16, 2013 |
| NRC Officer: | Daniel Mills |
| Last Updated: | Dec 16, 2013 |
| 49638 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 533922018-05-08T04:00:0008 May 2018 04:00:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 531592018-01-09T23:59:0009 January 2018 23:59:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Identified During National Fire Protection Association 805 Implementation ENS 524142016-12-07T19:43:0007 December 2016 19:43:00 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 Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 496382013-12-16T22:27:00016 December 2013 22:27:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Unfused Direct Current Ammeter Circuits 2018-05-08T04:00:00 | |