ENS 41698
ENS Event | |
|---|---|
20:00 May 13, 2005 | |
| Title | Unanalyzed Condition - Electrical Containment Penetration |
| Event Description | On March 23, 2005, with the plant at 100% power, an issue was discovered questioning the design of an approximately 3-inch diameter module of containment electrical penetration (PBP5D) used to feed a non-safety related lighting panel (L49E1) inside the containment building. Specifically, it was identified that this penetration module was protected from overcurrent by a single 30-amp breaker (BF503). Action was taken at that time to open the supply breakers de-energizing the lighting panel to prevent any potential fault on the subject penetration module while the issue was being evaluated.
Evaluations were initiated to determine the potential for the containment electrical penetration module to be thermally or mechanically damaged by a postulated fault. During this evaluation, no weak link upstream of the penetration module could be found that could be credited for preventing a fault in the penetration module in the event of a random failure of the breaker. The next breaker upstream of this circuit is too large to provide adequate overcurrent protection if the 30-amp breaker fails to open. Furthermore, it could not be shown that the electrical penetration module could withstand the maximum possible fault current while maintaining its containment integrity function. Therefore, it is now assumed that this postulated fault current could have damaged the penetration module to the extent that it would no longer have performed its containment integrity function. This condition is being reported within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of discovery in accordance with 10CFR50.72(b)(3)(ii)(B) as the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. Specifically, it was discovered that a system required to meet the single failure criterion does not do so. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Davis Besse  Ohio (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000346/LER-2005-003 Re Containment Electrical Penetration Not Equipped with Backup Electrical Fault Protection |
| Time - Person (Reporting Time:+-3.93 h-0.164 days <br />-0.0234 weeks <br />-0.00538 months <br />) | |
| Opened: | Tom Cobbledick 16:04 May 13, 2005 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | May 13, 2005 |
| 41698 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 573732024-10-10T14:45:00010 October 2024 14:45:00
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