ENS Event | |
|---|---|
16:17 Oct 30, 2013 | |
| Title | Postulated 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 in the control room has determined the described condition to be applicable to the Cooper Nuclear Station 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 control room ampere indications 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. This condition is being reported in accordance with 10 CFR 50.72(b)(3)(ii)(B). Interim compensatory measures (i.e.., fire watches) have been implemented for affected areas of the plant. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Cooper  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+0.43 h0.0179 days <br />0.00256 weeks <br />5.89014e-4 months <br />) | |
| Opened: | Brian Hasselbring 16:43 Oct 30, 2013 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Oct 30, 2013 |
| 49486 - NRC Website
Loading map... | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 544252019-12-05T14:10:0005 December 2019 14:10:00
[Table view]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 Fire Door Discovered Unlatched ENS 508542015-02-27T23:56:00027 February 2015 23:56:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Concerning Control Room Habitability Analysis ENS 494862013-10-30T16:17:00030 October 2013 16:17:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 460912010-07-13T22:07:00013 July 2010 22:07:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Containment Overpressure Not Ensured in the Appendix R Analysis 2019-12-05T14:10:00 | |