ENS 47024
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ENS Event | |
|---|---|
22:15 Jul 5, 2011 | |
| Title | Two Appendix R Wiring Issues That Could Potentially Affect the Ability to Shutdown |
| Event Description | On July 5, 2011, at 1815 hours0.021 days <br />0.504 hours <br />0.003 weeks <br />6.906075e-4 months <br />, it was determined that a design deficiency at the Perry Nuclear Power Plant (PNPP) constituted a fire protection program concern which could adversely affect the ability to achieve and maintain safe shutdown of the plant in the event of a control room fire. (Reference event notification numbers 46811 and 46997). In the event of a postulated control room fire, the potential exists that two 4160 VAC breakers could trip open under a hot-short condition.
PNPP's Appendix R design vulnerability only affects Breakers EH1106, which supplies the Emergency Service Water Pump A and EH1107, which supplies the Control Complex Chiller A. Specifically, the current transformers used in these breakers for the 50/51 instantaneous and time over current protective relays are in line with the component control room ammeters. Therefore, a hot-short-to-ground in the associated control room ammeters could actuate the 50/51 relays and trip the component breaker. Actions are in progress to isolate the control room ammeters for the Emergency Service Water Pump A in breaker EH1106 and the Control Complex Chiller A in breaker EH1107. Isolating these ammeters would isolate the affected circuitry from the described Appendix R failure mechanism. Control room amperage indication for the pump and chiller would be lost while this Temporary Modification is installed. PNPP will pursue a permanent resolution to the hot-short-to-ground fault for the EH1106 and EH1107 breakers. This event is being reported in accordance with 10 CFR 50.72(b)(3)(ii)(B), as a condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. A follow-up licensee event report will be made in 60 days. The resident inspector has been notified. |
| Where | |
|---|---|
Perry  Ohio (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000440/LER-2011-001 |
| Time - Person (Reporting Time:+-1.67 h-0.0696 days <br />-0.00994 weeks <br />-0.00229 months <br />) | |
| Opened: | Glendon Burnham 20:35 Jul 5, 2011 |
| NRC Officer: | Charles Teal |
| Last Updated: | Jul 5, 2011 |
| 47024 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 570922024-04-25T21:55:00025 April 2024 21:55:00
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