ML11327A026
| ML11327A026 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 11/22/2011 |
| From: | Riemer K R, Nirodh Shah NRC/RGN-III |
| To: | |
| References | |
| PNO-III-11-016 | |
| Download: ML11327A026 (1) | |
Text
PRELIMINARY NOTIFICATION - REGION III November 22, 2011 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE
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 III staff.
Facility Monticello Nuclear Generating Plant Northern States Power Co. Monticello, MN Docket: 50-263 License: DPR-22 Licensee Emergency Classification Notification of Unusual Event Alert Site Area Emergency General Emergency X Not Applicable
SUBJECT:
MONTICELLO SHUTDOWN GREATER THAN 72 HOURS DUE TO ACTUATION OF REACTOR PROTECTION RELAYS SENSING LOW TURBINE CONTROL VALVE HYDRAULIC PRESSURE DESCRIPTION:
On November 19, 2011, Monticello experienced a reactor scram following the unexpected actuation of the relays used to trip the reactor when adequate turbine control valve hydraulic pressure is not maintained. Hydraulic fluid is used to actuate valves that allow steam to be transmitted to the turbine for the generation of electricity. As a protective feature, the reactor is designed to anticipatorily shut down should the hydraulic pressure drop below a specific value. The relay actuation occurred during routine turbine control valve testing and the nature of the actuation is currently under investigation. The reactor responded as expected to the received signals and there was no adverse effect to public health and safety from this event.
The NRC resident inspectors responded to the reactor scram and are monitoring the licensee's investigation and repairs of the affected equipment.
This preliminary notification is issued for information only. State and local officials have been informed. The site issued a press release on November 20, 2011, describing the event.
The information presented herein has been discussed with the licensee, and is current as of 10:00 a.m. (CST), on November 22, 2011.
ADAMS Accession Number ML11327A026.
CONTACTS: Ken Riemer Nirodh Shah 630/829-9628 630/829-9821 Kenneth.Riemer@nrc.gov Nirodh.Shah@nrc.gov