PNO-III-15-010, A UPDATE-Monticello Automatic Scram Due to Reactor Protection System Signal
| ML15337A504 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/03/2015 |
| From: | Kenneth Riemer Division Reactor Projects III |
| To: | |
| References | |
| PNO-III-15-010A | |
| Download: ML15337A504 (1) | |
PRELIMINARY NOTIFICATION - REGION III December 3, 2015 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PNO-III-15-010A 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 Licensee Emergency Classification Monticello Nuclear Generating Plant Notification of Unusual Event Northern States Power Co. Alert Monticello, MN Site Area Emergency Docket: 50-263 General Emergency License: DPR-22 X Not Applicable
SUBJECT:
UPDATE: MONTICELLO AUTOMATIC SCRAM DUE TO REACTOR PROTECTION SYSTEM SIGNAL DESCRIPTION:
On November 30, 2015, the Monticello Nuclear Generating Plant was restarted following an automatic reactor shutdown occurring on November 23, 2015. Specifically, on November 23, there was an unexpected lockout of the 11 recirculation pump; this pump is used to circulate and control the flow of water through the reactor core. Shortly after the lockout, the Reactor Protection System detected an invalid indicated high steam flow in the main steam lines, prompting an automatic reactor shutdown.
The cause of the recirculation pump lockout was determined to be a loose wire connection on the pump control circuitry. The cause of the indicated high steam flow was a pressure transient caused by foreign material partially blocking the pressure sensing line. Both issues were corrected as part of the licensees investigation and troubleshooting efforts.
The NRC senior resident inspector was on site to observe the shutdown, portions of the licensees troubleshooting efforts, and portions of the startup.
This preliminary notification is issued for information only and no further action by the staff is anticipated.
Region III received initial notification of this occurrence via the Resident Inspector at 10:42 am (CST) on November 23, 2015. The information presented herein has been discussed with the licensee, and is current as of 3:00 p.m. (CST), on December 3, 2015.
ADAMS Accession Number ML15337A504.
CONTACT: Kenneth Riemer 630/829-9628 Kenneth.Riemer@nrc.gov
PRELIMINARY NOTIFICATION - REGION III December 3, 2015 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PNO-III-15-010A 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 Licensee Emergency Classification Monticello Nuclear Generating Plant Notification of Unusual Event Northern States Power Co. Alert Monticello, MN Site Area Emergency Docket: 50-263 General Emergency License: DPR-22 X Not Applicable
SUBJECT:
UPDATE: MONTICELLO AUTOMATIC SCRAM DUE TO REACTOR PROTECTION SYSTEM SIGNAL DESCRIPTION:
On November 30, 2015, the Monticello Nuclear Generating Plant was restarted following an automatic reactor shutdown occurring on November 23, 2015. Specifically, on November 23, there was an unexpected lockout of the 11 recirculation pump; this pump is used to circulate and control the flow of water through the reactor core. Shortly after the lockout, the Reactor Protection System detected an invalid indicated high steam flow in the main steam lines, prompting an automatic reactor shutdown.
The cause of the recirculation pump lockout was determined to be a loose wire connection on the pump control circuitry. The cause of the indicated high steam flow was a pressure transient caused by foreign material partially blocking the pressure sensing line. Both issues were corrected as part of the licensees investigation and troubleshooting efforts.
The NRC senior resident inspector was on site to observe the shutdown, portions of the licensees troubleshooting efforts, and portions of the startup.
This preliminary notification is issued for information only and no further action by the staff is anticipated.
Region III received initial notification of this occurrence via the Resident Inspector at 10:42 am (CST) on November 23, 2015. The information presented herein has been discussed with the licensee, and is current as of 3:00 p.m. (CST), on December 3, 2015.
ADAMS Accession Number ML15337A504.
CONTACT: Kenneth Riemer 630/829-9628 Kenneth.Riemer@nrc.gov