ENS Event | |
|---|---|
20:52 Nov 7, 2013 | |
| Title | Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment |
| Event Description | A review of industry operating experience regarding the impact of unfused Direct Current (DC) ammeter circuits has determined the described condition to be applicable to the Palisades Nuclear Plant resulting in a potentially unanalyzed condition with respect to 10 CFR 50 Appendix R analysis requirements.
The original plant wiring design and associated analysis for the Class 1E batteries ampere indications, located in the cable spreading room at Palisades, do not include overcurrent protection features to limit the fault current. In the postulated event, a fire could cause one of the ammeter wires to short to ground. Simultaneously, it is postulated that the fire causes another DC wire from the opposite polarity on the same battery to also short to ground. This could cause a ground loop through the unprotected ammeter wiring. This event could result in excessive current flow (i.e., heating) in the ammeter wiring to the point of causing a secondary fire in the raceway system. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10 CFR 50 Appendix R. Interim compensatory measures (i.e., fire tours) have been implemented for affected areas of the plant. This condition is being reported in accordance with 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Palisades  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-4.33 h-0.18 days <br />-0.0258 weeks <br />-0.00593 months <br />) | |
| Opened: | Terry Davis 16:32 Nov 7, 2013 |
| NRC Officer: | Dong Park |
| Last Updated: | Nov 7, 2013 |
| 49516 - NRC Website
Loading map... | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 526472017-03-29T19:08:00029 March 2017 19:08:00
[Table view]10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 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 495162013-11-07T20:52:0007 November 2013 20:52:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 473222011-09-26T10:02:00026 September 2011 10:02:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Appendix R Equipment May Not Have Been Available ENS 463022010-10-01T17:25:0001 October 2010 17:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Appendix R Non-Compliance Issue Identified ENS 429592006-11-02T19:36:0002 November 2006 19:36:00 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 High Pressure Safety Injection (Hpsi) Pumps Alignment Blocks Improperly Installed ENS 423372006-02-14T21:00:00014 February 2006 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Appendix "R" Related Unanalyzed Condition 2017-03-29T19:08:00 | |