PNO-IV-13-002, C Update Arkansas Nuclear One, Unit 1, Return to Power Operation
| ML13220B087 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 08/08/2013 |
| From: | Allen D, Brian Tindell NRC/RGN-IV/DRP/RPB-E |
| To: | |
| AMT / Don Allen | |
| References | |
| PNO-IV-13-002C | |
| Download: ML13220B087 (2) | |
August 8, 2013 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-IV-13-002C This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region IV, Arlington, Texas, staff on this date.
Facility Licensee Emergency Classification Arkansas Nuclear One, Units 1 and 2 _ Notification of Unusual Event Entergy Alert Russellville, Arkansas Site Area Emergency Dockets: 05000313; 05000368 General Emergency License Nos. DPR-51; NPF-6 X Not Applicable
SUBJECT:
ARKANSAS NUCLEAR ONE, UNIT 1, RETURN TO POWER OPERATION (UPDATE)
DESCRIPTION:
On August 6, 2013, the licensee restarted the Unit 1 reactor. On August 7, 2013, the main generator was synchronized to the grid.
This preliminary notification supplements information in PNO-IV-13-002, PNO-IV-13-002A, and PNO-IV-13-002B, issued to describe the event that occurred at Arkansas Nuclear One (ANO),
Units 1 and 2 on March 31, 2013 (ADAMS ML13092A024, ML13099A244 and ML13121A273).
During transfer of the 500 ton ANO Unit 1 main generator stator, the lifting rig failed. The main generator stator fell approximately 30 feet into the train bay and caused structural damage to the Unit 1 turbine building. For ANO Unit 1, which was in a refueling outage, this drop caused a loss of offsite power. This resulted in the Unit 1 Emergency Diesel Generators (EDGs) operating to provide power to vital electrical loads. ANO Unit 2 experienced a reactor trip from 100 percent power after the falling stator and crane components caused a reactor coolant pump electrical breaker to open. About 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> later, water from a damaged fire suppression system piping resulted in loss of power to one vital electrical bus and a Notification of Unusual Event. The associated EDG for Unit 2 started and supplied power to safety related equipment.
On April 8, 2013, the NRC sent an Augmented Inspection Team (AIT) to assess the circumstances surrounding the March 31, 2013 incident. The team reviewed the Unit 1 loss of offsite power and the Unit 2 reactor trip and subsequent Notification of Unusual Event. The NRC conducted a public exit meeting to discuss the results of the augmented inspection on May 9, 2013. The AIT inspection results are documented in Report 05000313/2013011 and 05000368/2013011 (ML13135A503).
On April 28, 2013, following repairs and retesting of electrical equipment, the licensee restarted Unit 2. The NRC inspected the repairs to Unit 2 and observed portions of the Unit 2 restart.
The NRC continued to inspect the licensees actions to repair the damage to the Unit 1 turbine building and equipment, and to complete the scheduled refueling outage. NRC inspectors will continue oversight now that both units have returned to service.
This preliminary notification is issued for information only.
This information presented herein has been discussed with the licensee and is current as of 8:05 a.m. (CDT) on August 8, 2013.
CONTACTS:
Don Allen, Branch Chief, (817) 528-3439 Brian Tindell, Senior Resident Inspector, ANO, (479) 857-9199 ADAMS ACCESSION NUMBER: ML13220B087