ENS 49419
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ENS Event | |
|---|---|
17:40 Oct 8, 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 in the control room has determined the described condition to be applicable to Comanche Peak Nuclear Power Plant resulting in a potentially unanalyzed condition with respect to 10CFR50 Appendix R analysis requirements. The original plant wiring design and associated analysis for the Class 1 E batteries control room ampere indications do not include overcurrent protection features to limit the fault current.
In the postulated event, a fire in the control room could cause one of the ammeter wires to hot short to the ground plane. Simultaneously, the fire causes another DC wire from the opposite polarity on the same battery to also hot short to the ground plane. This could cause a ground loop through the unprotected ammeter wiring. This event could result in excessive current flow (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 10CFR50 Appendix R. This condition is reportable in accordance with 10CFR50.72(b)(3)(ii)(B) as an unanalyzed condition. Compensatory measures (fire watches) have been implemented for affected areas of the plant. The licensee has notified the NRC Resident Inspector. See related Event #49411. |
| Where | |
|---|---|
Comanche Peak  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000445/LER-2013-002 Regarding Unanalyzed Condition Under 10CFR50 Appendix R Secondary Fires from Unprotected Ammeter Wiring |
| Time - Person (Reporting Time:+-1.97 h-0.0821 days <br />-0.0117 weeks <br />-0.0027 months <br />) | |
| Opened: | John Rasmussen 15:42 Oct 8, 2013 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Oct 8, 2013 |
| 49419 - 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 528172017-06-21T15:00:00021 June 2017 15:00:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Fire Event Could Adversely Impact Safe Shutdown Equipment ENS 526462017-03-29T00:57:00029 March 2017 00:57:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition for a Postulated Moderate Energy Line Break ENS 524842017-01-11T21:00:00011 January 2017 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Teflon Found in Containment Spray Pump Components ENS 522442016-09-15T20:40:00015 September 2016 20:40:00 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, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Potential Degradation of Eccs Pump Pressure Indicators ENS 522392016-09-13T22:30:00013 September 2016 22:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Involving Station Service Water Trains ENS 522172016-09-01T15:25:0001 September 2016 15:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition on Turbine Driven Auxiliary Feedwater Pump ENS 517512016-02-23T23:00:00023 February 2016 23:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Involving Normally Open Battery Room Doors ENS 508352015-02-19T22:00:00019 February 2015 22:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Involving Normally Closed Watertight Doors ENS 500432014-04-18T17:52:00018 April 2014 17:52:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Cable Routing Unanalyzed for Fire Safe Shutdown Barrier ENS 494192013-10-08T17:40:0008 October 2013 17:40:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 477132012-03-01T23:05:0001 March 2012 23:05:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Battery Room Ventilation System Degraded ENS 473572011-10-20T01:02:00020 October 2011 01:02:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Pressure Instruments Containing Aluminum Material ENS 473522011-10-18T20:45:00018 October 2011 20:45:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Aluminum Valve Discovered Installed in Containment ENS 470862011-07-21T16:53:00021 July 2011 16:53:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Vulnerability from a Potential Control Room Fire on "a" Safeguards Bus ENS 435622007-08-13T14:00:00013 August 2007 14:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Inadequate Fire Protection on Safety Chilled Water System Electrical Cables 2017-06-21T15:00:00 | |
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