ML14148A014
| ML14148A014 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/28/2014 |
| From: | Raymond McKinley NRC/RGN-I/DRP/PB5 |
| To: | |
| McKinley R R | |
| References | |
| PNO-I-14-002 | |
| Download: ML14148A014 (3) | |
Text
Date: May 28, 2014
PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE
- PNO-I-14-002 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. Some of the information may not yet be fully verified or evaluated by the Region I staff.
Facility Licensee Emergency Classification Dominion Nuclear Connecticut, Inc. _X_ Notification of Unusual Event Millstone Power Station, Units 2 and 3 ___ Alert Waterford, CT ___ Site Area Emergency Docket Nos. 50-336, 50-423 ___ General Emergency License Nos. DPR-65, NPF-49 ___ Not Applicable
SUBJECT:
MILLSTONE POWER STATION UNITS 2 AND 3: UNUSUAL EVENT DECLARED DUE TO LOSS OF OFFSITE POWER AND DUAL REACTOR TRIPS On May 25, 2014, at 7:02 a.m. EST, Millstone Power Station Unit 2 and 3 experienced a Dual Unit trip due to loss of off-site power (LOOP). At 07:15 a.m., Millstone declared a Notification of Unusual Event (NOUE) due to a LOOP. The LOOP was due to a localized issue in the Millstone switchyard and the surrounding areas were not affected by the power loss. The Region 1 Incident Response Center entered monitoring mode at 7:49 a.m. and exited at 3:02 p.m. on May 25, 2014. Dominion exited the NOUE at 2:14 p.m. on May 25, 2014. Both units are currently in a safe and stable condition.
Millstone Unit 2 responded normally. Unit 2 Emergency Diesel Generators (EDGs) started and supplied power to all safety buses and all safety systems responded as designed. Millstone Unit 3 experienced an unexpected loss of non-safety instrument air following the LOOP, which complicated the recovery actions. The normal reactor coolant system letdown flow path was not able to be established and this resulted in the rupture of the pressurizer relief tank rupture disk inside containment. The relief valve on the volume control tank lifted when restoring normal letdown. This caused the primary drains transfer tank to overflow into the auxiliary building. This overflow path was isolated, and the normal letdown was subsequently restored. Both Unit 3 EDGs started and supplied power to all safety buses and all safety systems responded as designed. Off-site power was restored as of 12:56 p.m. on May 25, 2014. The NRC residents responded to the site and continue to closely follow Dominion's actions. NRC oversight is being conducted through the NRC's baseline inspection program.
After evaluating the causes of the event and assessing equipment condition, Dominion restarted Unit 2 on May 27, 2014. Return to service of Unit 3 is pending additional evaluations and equipment repairs.
Region I Public Affairs Officers have responded to media inquiries. The Federal Emergency Management Agency (FEMA) and the State of Connecticut have been informed of the event and licensee response activities. The information presented herein has been discussed with Dominion and is current as of May 28, 2014, at 7:00 a.m.
2 This preliminary notification is issued for information only and no further notification by the staff is anticipated.
ADAMS Accession Number: ML14148A014 CONTACT: Raymond McKinley, Projects Branch 5 (610) 337-5150 Raymond.McKinley@nrc.gov
ML14148A014 SUNSI Review Non-Sensitive Sensitive Publicly Available Non-Publicly Available OFFICE RI/DRP RI/DRP RI/PAO RI/SLO RI/ORA NAME RMcKinley/RRM HNieh/HKN DScrenci/NS for NMcNamara/DBT for WDean/DCL for DATE 5/27/14 5/27/14 5/27/14 5/27/14 5/28/14