ENS 48283
ENS Event | |
|---|---|
18:16 Sep 6, 2012 | |
| Title | Both Offsite Power Sources Inoperable |
| Event Description | At 1416 EDT, after consultation with the Unit 1 control room, the #1 138 KV bus in the Beaver Valley switchyard was deenergized by the grid system operator in response to a degraded switchyard breaker. The bus loss caused the Unit 1 A train offsite power supply to be inoperable. The Unit 1 B train offsite power supply was previously inoperable due to planned maintenance on its transformer cooling fan control circuit. The Unit 1 B train offsite power supply remained energized and available during this event. Both Emergency Diesel Generators remained operable and both emergency buses remained energized from the onsite source and operable during this event.
At 1425 EDT the #1 138 KV bus was re-energized. The planned maintenance was completed on the B train offsite power supply transformer. Following testing, at 1452 EDT both offsite power supplies were declared operable. This notification is provided in accordance with 10CFR50.72(b)(3)(v)(D) since both offsite power supplies were inoperable from 1416 EDT to 1452 EDT on 9/6/12. The licensee notified the NRC Resident Inspector.
Beaver Valley Unit 1 is retracting EN 48283 based on completion of an engineering evaluation. The evaluation determined that the Unit 1 'B' train offsite power supply was operable and capable of performing its safety function with its transformer cooling fan control circuit out of service for planned maintenance. Since one train of offsite power was determined to be operable, this condition is not reportable under 10CFR50.72(b)(3)(v)(D). The NRC Resident Inspector has been notified." Notified R1DO (Wayne Schmidt). |
| Where | |
|---|---|
| Beaver Valley Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+1.07 h0.0446 days <br />0.00637 weeks <br />0.00147 months <br />) | |
| Opened: | Robert Kristophel 19:20 Sep 6, 2012 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Oct 1, 2012 |
| 48283 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |