05000302/LER-1980-030-03, /03L-0:on 800731,during Monthly Diesel Generator Surveillance,Emergency Diesel Generator B Tripped as Result of Separation of Turbocharger Discharge Ductwork Due to Sheared Bolts on Mounting Bracket.Caused by Vibration

/03L-0:on 800731,during Monthly Diesel Generator Surveillance,Emergency Diesel Generator B Tripped as Result of Separation of Turbocharger Discharge Ductwork Due to Sheared Bolts on Mounting Bracket.Caused by Vibration

ML19344E027
Person / Time
Site:	Crystal River
Issue date:	08/22/1980
From:	Neuschaefer E FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19344E021	List: 05000302/LER-1980-030, Forwards LER 80-030/03L-0 05000302/LER-1980-030-03, /03L-0:on 800731,during Monthly Diesel Generator Surveillance,Emergency Diesel Generator B Tripped as Result of Separation of Turbocharger Discharge Ductwork Due to Sheared Bolts on Mounting Bracket.Caused by Vibration
References
LER-80-030-03L, LER-80-30-3L, NUDOCS 8008260532
Download: ML19344E027 (2)

LER-1980-030, /03L-0:on 800731,during Monthly Diesel Generator Surveillance,Emergency Diesel Generator B Tripped as Result of Separation of Turbocharger Discharge Ductwork Due to Sheared Bolts on Mounting Bracket.Caused by Vibration

Event date:
Report date:
3021980030R03 - NRC Website

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SUPPLEMENTARY INFORMATION Report No.:

50-302/80-030/03L-0 Facility:

Crystal River Unit #3 Report Date:

22 August 1980 Occurrence Date:

31 July 1980 Identification of Occurrence:

Failure to have the required number of A.C. electrical power sources operable contrary to Technical Specification 3.8.1.1.

Conditions Prior to Occurrence:

Mode 4 hot shutdown.

Description of Occurrence:

At 2250 while performing SP-354, Emergency Diesel Fuel Oil Quality and Diesel Generator Monthly Test, the "If' emergency diesel generator tripped.

The trip resulted from separation of the turbocharger discharge ductwork, due to sheared bolts on the mounting bracket. Redundancy was maintained by the remaining diesel generator and two physically independent offsite circuits.

Designation of Apparent Cause:

The apparent cause of this event is attributed to loosening of the bolts to the mounting bracket of the turbocharger discharge ductwork due to vibration. Once loosened, mechanical fatigue occurred causing the bolts to shear.

Analysis of Occurrence:

No effect upon the general public as the plant remained in a safe shutdown condition.

Corrective Action

A modification has been made to add lock washers to the bolts to prevent recurrence. Operability of the "B" emergency diesel generator was restored at 2120 on 4 August 1980.

Failure Data:

This is the first occurrence of this type; however, the eighteenth event reported under this specification.

/rc