ML091870321
| ML091870321 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/03/2009 |
| From: | Barber G S NRC/RGN-I/DRP/PB6 |
| To: | |
| Barber G S, RGN-I/DRP/610-337-5232 | |
| References | |
| FOIA/PA-2011-0115 PNO-I-09-004 | |
| Download: ML091870321 (2) | |
Text
DCS No.: 0500033607032009 Date: July 3, 2009
PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-I-09-004
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 I staff on this date.
Facility Dominion Nuclear Connecticut Millstone Unit 2 Waterford, CT Docket: 50-336 Licensee Emergency Classification Notification of Unusual Event Alert Site Area Emergency General Emergency X Not Applicable
SUBJECT:
MILLSTONE UNIT 2 REACTOR TRIP AND SHUTDOWN GREATER THAN 72 HOURS On July 3, at 1:04 p.m., the Millstone Unit 2 main turbine stop valves inadvertently closed which resulted in a high primary pressure condition that caused a reactor trip. During the transient, all safety systems operated appropriately. The plant was safely placed in hot shutdown.
The licensee continues to review the cause for the stop valve closure, which occurred during a perturbation in the offsite electrical grid (Montville Line). Additionally, the licensee is reviewing other anomalies during the transient including the loss of two non-safety related busses and the failure of the main feedwater regulating valves to close.
Because the turbine stop valves closed first rather than the turbine control valves, the turbine trip did not result in an automatic reactor trip, as designed. The resultant increase in primary and secondary system pressures from the transient caused the primary power operated relief valves to open, as well as the condenser bypass, secondary atmospheric and steam generator safety valves.
The licensee decided to take the plant to cold shutdown to effect repairs to a degraded "A" reactor coolant pump vapor seal, which was an existing equipment issue that was unrelated to the plant trip.
State and local officials have been informed.
The NRC Region I Public Affairs Office is responding to media inquiries.
The information presented herein has been discussed with Dominion and is current as of July 6, 2009 at 11:00 a.m.
NRC Region I will update this PN after plant restart.
ADAMS Accession Number: ML091870321
CONTACT: Scott Barber (610) 337-5232 2DISTRIBUTION: (PN Recipient List)
Chairman Jazcko Comm. Klein Comm. Svinicki OIP OCA OGC OPA EDO OE NRR SECY IRO NMSS ACRS OIG RES NSIR NRO PDR RSLO Regional Offices
By Fax:
DOT:Trans INPO NSAC RI Resident Office
Licensee: Dominion Nuclear Connecticut (Millstone 2)
ADAMS Accession Number: ML091870321 SUNSI Review Complete: SB ___ (Reviewer's Initials)
DOCUMENT NAME: G:\DRP\PNs\PNO-I-09-004 - MP2 Rx Trip due offsite line disturbance.doc After declaring this document "An Official Agency Record" it will be released to the Public.
To receive a copy of this document, indicate in the box:
" C" = Copy without attachment/enclosure " E" = Copy with attachment/enclosure " N" = No copy OFFICE RI/DRP RI/ORA RI/PAO RI/DRP NAME SBarber DTifft DScrenci DLew DATE 07/06/09 07/06/09 07/06/09 07/06/09 OFFICIAL RECORD COPY Region I Form 83 (Rev. July 2, 2003)