PNO-I-90-061, on 900806,plant Operators Manually Scrammed Reactor Due to High Vibration on Main Turbine Bearing.Caused by Blank Flange Left in Oil Supply Line to Bearing.Resident Inspectors Following Licensee Actions

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PNO-I-90-061:on 900806,plant Operators Manually Scrammed Reactor Due to High Vibration on Main Turbine Bearing.Caused by Blank Flange Left in Oil Supply Line to Bearing.Resident Inspectors Following Licensee Actions
ML20058M364
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 08/07/1990
From: Cowgill C, Temps R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-90-061, PNO-I-90-61, NUDOCS 9008100080
Download: ML20058M364 (1)


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.-. . OCS No: 050220090807 Date: August 7, 1990 c PREllMiNARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-1-90-61 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: Licensee Emergency Classification:

Niagara Mohawk Power Corporation Notification of Unusual Event Nine Mile Point Unit 1 Alert Oswego, New York Site Area Emergency DN 50-220 General Emergency 1 Not Applicable

Subject:

MANUAL REACTOR SCRAM FOLLOWING EXCESSIVE TURBINE BEARING VIBRATION At about 5:32 p.m. on August 6, 1990, plant operators manually scrammed the reactor due to high vibration on a main turbine bearing. The vibration was detected during

. preparations for placing the main turbine on line. Main condenser-vacuum was broken to more quickly reduce turbine speed to prevent further damage to the bearing. The operators performed well during the event and all plant systems responded as required. The plant is in cold shutdown as of 8:00 a.m. on August 7.

The-bearing will apparently require replacement. Preliminary indications are that a blank flange, left in the oil supply line to the bearing, was the cause of the event.

A press statement issued by Niagara Mohawk indicated that they planned to restart the unit in approximately one week pending completion of post-event investigation and replacement of the bearing as well as other miscellaneous maintenance items. The resident inspectors are following licensee actions on site.

The State of New York has been notified.

CONTACT: R. Temps, R1 C. Cowgill, RI 8-215-342-4041 FTS 346-5233 DISTRIBUTION:

OWFN MNBB L-St. NL Mail: ADM:0MB Chairman Carr AEOD fils DOT:Trans only Comm. Roberts IRM POR Comm. Rogers O1G NRC Ops Ctr

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GPA. NRR PA - OE Regional Offices SLITP RI Resident Office EW-KSLAP Licensee:

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Regi.on 1 Form 83 (Rev. April 1988) ym mm vhi PNO-I-90-061 n.

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