ENS 49449
ENS Event | |
|---|---|
12:30 Oct 18, 2013 | |
| Title | Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment |
| Event Description | At 0830 EDT, Calvert Cliffs Nuclear Power Plant determined that the following was an unanalyzed condition:
As a result of recent industry operating experience (OE 305419) regarding the impact of unfused direct current (DC) ammeter circuits in the Control Room, Calvert Cliffs performed a review of ammeter circuitry. The review determined the described condition to be applicable to Calvert Cliffs 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 or charger. The ammeter wiring attached to the shunt does not contain fuses. It is postulated that a fire in the Unit 1 Cable Spreading Room could cause one of the ammeter wires to hot 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 unfused ammeter cable. The potential exists that the cable could heat-up causing a secondary fire in the Unit 2 Cable Spreading Room. 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 as an eight hour ENS report in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. Compensatory measures (fire watches) have been implemented for affected areas of the plant. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Calvert Cliffs  Maryland (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+1.58 h0.0658 days <br />0.0094 weeks <br />0.00216 months <br />) | |
| Opened: | Dan Geneva 14:05 Oct 18, 2013 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Oct 18, 2013 |
| 49449 - 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 536632018-10-11T04:00:00011 October 2018 04:00:00
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