PNO-III-07-007, Point Beach - Unit 1 Manual Reactor Trip
| ML071590290 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/08/2007 |
| From: | NRC/RGN-III |
| To: | |
| References | |
| PNO-III-07-007 | |
| Download: ML071590290 (1) | |
June 8, 2007 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-III-07-007 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 III staff on this date.
Facility Point Beach Unit 1 Nuclear Management Company, LLC Two Rivers, WI Docket: 50-266 License: DPR-24 Licensee Emergency Classification Notification of Unusual Event Alert Site Area Emergency General Emergency x Not Applicable
SUBJECT:
UNIT 1 MANUAL REACTOR TRIP DESCRIPTION:
On June 5, 2007, reactor operators manually tripped the Unit 1 reactor in response to the loss of 'B' train main feedwater control. Upon initial indications of abnormal feedwater flow, the operators entered the abnormal operating procedure for a feedwater system malfunction. An immediate inspection of the B main feedwater regulating valve determined that the valve positioner arm was disconnected, and operators in the field reported that the valve was cycling full open to full shut. Following the reactor trip, the auxiliary feedwater system actuated, as designed, because of the feedwater transient prior to the reactor trip. All safety systems functioned as designed. Following the manual trip, an unexpected switchyard bus lockout occurred; however, offsite power was maintained throughout the event. The licensee made the required four hour and eight hour notifications.
The licensee determined the cause of the main feedwater regulating valve positioner arm failure was improper maintenance performed on the valve during the most recent Unit 1 outage which ended in May 2007. The licensee has corrected this condition and is addressing the extent of condition. The licensee continues to investigate the cause of the unexpected switchyard bus lockout, to determine what repairs are necessary prior to restart of Unit 1. The duration of the Unit 1 shutdown as a result of the trip is expected to exceed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The State of Wisconsin will be notified.
This information is current as of 9:30 a.m. on June 8, 2007.
The information in this preliminary notification has been reviewed with license management.
CONTACTS:
Jamnes Cameron Robert Krsek 630/829-9833 920/755-2309