PNO-III-15-003, A: Update: Shutdown of Prairie Island Unit 2 Due to Loss of Instrument Air to Containment Building

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PNO-III-15-003A: Update: Shutdown of Prairie Island Unit 2 Due to Loss of Instrument Air to Containment Building
ML15085A284
Person / Time
Site: Prairie Island Xcel Energy icon.png
Issue date: 03/26/2015
From: Kenneth Riemer
NRC/RGN-III/DRP/B2
To:
Northern States Power Co
References
PNO-III-15-003A PNO-III-15-003A
Download: ML15085A284 (1)


PRELIMINARY NOTIFICATION March 26, 2015 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE-PNO-III-15-003A 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 Prairie Island Nuclear Plant Notification of Unusual Event Northern States Power Co. Alert Welch, MN Site Area Emergency Docket: 50-306 General Emergency License: DPR-60 X Not Applicable

SUBJECT:

UPDATE: SHUTDOWN OF PRAIRIE ISLAND UNIT 2 DUE TO LOSS OF INSTRUMENT AIR TO CONTAINMENT BUILDING Prairie Island Unit 2 was shut down on March 5, 2015, after a valve supplying instrument air to the containment building failed. Instrument air is used to operate many of the valves and components in the plant. Without instrument air, the plant was directed to be shut down by procedure.

During the shutdown process steam and water were released into the containment from a relief tank due to the activation of a rupture disk, an expected result given the loss of instrument air to the containment. Several thousand gallons of water drained into the Unit 2 containment building. This water was collected in the containment sump and was not released to the environment. After the shutdown, licensee staff and the NRC resident inspectors observed that the water had caused no significant damage to plant equipment. There was no risk to the public health and safety from this event.

On March 25, 2015, Prairie Island Unit 2 was restarted following completion of repairs to the failed valve and the pressure relief tank. The Resident Inspectors were on site and monitored portions of the startup activities.

This preliminary notification is issued for information only and no further action by the staff is anticipated. State officials have been informed.

The information presented herein has been discussed with the licensee, and is current as of 11:40 am CDT, on March 26, 2015.

ADAMS Accession Number: ML15085A284 CONTACT: Kenneth Riemer 630-829-9628 Kenneth.Riemer@nrc.gov