ML19319B749

RO NP-33-77-42:on 770729,main Steam Supply Line Check Valve MS734 Bonnet Leaked.Caused by Gasket Failure Due to Relaxation of Bolts.Bonnet Gasket Replaced & Auxiliary Feed Pump Turbine 1-1 Returned to Svc on 790729

ML19319B749
Person / Time
Site:	Davis Besse
Issue date:	08/23/1977
From:	Cheska R, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19319B639	List: ML19319B638 ML19319B749
References
NUDOCS 8001270210
Download: ML19319B749 (2)

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4 s_,/ TOLEDO EDIS. "C 2 A !Y DAVIS-BESSE UNIT CNE :L G POWER STATION SUPPLEME!;TAL INFORMATIO:. FOR !.ER NP-33-77-42 DATE OF EVE';T: July 29, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Auxiliary Feed Pu=p Turbine (AFFT) 1-1 Main Stea=

Supply Line Check Valve (MS734) bonnet leak Conditions Prior to occurrence: The plant was in Mode 3, with Power (MWT) = 0 and Load (MWE) = 0.

Descriotion of Occurrence: At 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> on July 29, 1977 while Operations personnel were running Surveillance Test (ST 5071.01) " Auxiliary Feedwater Monthly Test", Main Steam Supply Line Check Valve MS734 was discovered to have steam leaking around the bonnet. The Maintenance Department was i==ediately notified and steam to AFPT l-1 was secured so Maintenance personnel could repair MS734. While repairs on MS734 were underway, Maintenance personnel also

~g made some governor adjust =ents. AFFT l-1 was therefore inoperable which places the Station in the Action Statement of Technical Specification 3.7.1.2. At 4 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br /> on July 29, 1977, the Surveillance Test (ST 5071.01) was co=;;eted and AFFT 1-1 was declared operable.

Designation of Anoarent Cause of Occurrence: Gasket on bonnet failed due to relaxation of bonnet bolts. Four out of the eight bolts were found to be only finger tight. The exact cause of this relaxation is not known.

Analysis of Occurrence: Since AFPT 1-2 was operable at the ti=e and the Reacter had not yet reached initial criticality, there was no danger to the health and safety of the public or Station personnel.

Corrective Action: The leaky valve bonnet was repaired by replacing the bonnet gasket with a new one and AFPT 1-1 was returned to operable status at 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br /> on July 29, 1977, removing the Station from the Action Statement of Technical Specification 3.7.1.2.

i Fatbtre]at  : On July 27, 1977, both Auxiliary Feedwater Systems were inot erable

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