ENS Event | |
|---|---|
02:03 Aug 21, 2007 | |
| Title | Inoperable House Service Transformers |
| Event Description | This report is made in compliance with Tech spec 2.7, 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> NRC notification of inoperable house service transformers. The 161 Kv electrical supply to both house service transformers T1A-3 and T1A-4 was lost at 21:03 EDT. Fast transfer to 22 Kv was successful. AOP-31, 161 Kv Grid Malfunctions, abnormal operating procedure was entered. Technical Specification 2.7 (2) c, 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO was entered.
Background: The site was in a tornado warning between 20:30 and 21:00 EDT. Wind speeds were observed in excess of 60 mph by the site weather tower. One of the two switchyard breakers 3451-5 on the 345 Kv system opened at 20:50 EDT. The 345 Kv output breaker 3451-4 remained closed. The EDG are in standby and ready for service if required. The licensee notified the NRC Resident Inspector.
The 161Kv electrical supply has been returned to service and Tech Spec 2.7(2)c has been exited at 0029 EDT on 08/21/07. Breaker 3451-5 remains open. System walk downs have to be completed before breaker 3451-5 can be closed. R4DO (J. Clark) notified. The NRC Resident Inspector is presently in the control room. |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+-3.95 h-0.165 days <br />-0.0235 weeks <br />-0.00541 months <br />) | |
| Opened: | Kevin Boston 22:06 Aug 20, 2007 |
| NRC Officer: | John Knoke |
| Last Updated: | Aug 21, 2007 |
| 43582 - NRC Website
Loading map... | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 521882016-08-17T23:26:00017 August 2016 23:26:00
[Table view]Other Unspec Reqmnt Offsite Power Source Below the Operability Limit ENS 458982010-05-04T20:12:0004 May 2010 20:12:00 Other Unspec Reqmnt Discovery of After-The- Fact Emergency Condition - Unusual Event Due to Rcs Lineup ENS 436782007-10-01T18:15:0001 October 2007 18:15:00 Other Unspec Reqmnt Replacing the Emergency Response Facility Computer System ENS 435822007-08-21T02:03:00021 August 2007 02:03:00 Other Unspec Reqmnt Inoperable House Service Transformers ENS 408852004-07-20T23:18:00020 July 2004 23:18:00 Other Unspec Reqmnt 4-Hour Notification Required by Technical Specifications 2016-08-17T23:26:00 | |