05000346/LER-1980-069-03, /03L-0:on 800902,during Diesel Generator 1-1 Oil Change,Bolt Fragment Discovered in Crankcase Sump.Caused by Loose Bolts in Idler Gear to Support Spider of Turbocharger Spring Drive Assembly.Modified Assembly Installed

/03L-0:on 800902,during Diesel Generator 1-1 Oil Change,Bolt Fragment Discovered in Crankcase Sump.Caused by Loose Bolts in Idler Gear to Support Spider of Turbocharger Spring Drive Assembly.Modified Assembly Installed

ML19338F083
Person / Time
Site:	Davis Besse
Issue date:	10/02/1980
From:	Adams J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19338F066	List: 05000346/LER-1980-069, Forwards LER 80-069/03L-0 05000346/LER-1980-069-03, /03L-0:on 800902,during Diesel Generator 1-1 Oil Change,Bolt Fragment Discovered in Crankcase Sump.Caused by Loose Bolts in Idler Gear to Support Spider of Turbocharger Spring Drive Assembly.Modified Assembly Installed
References
LER-80-069-03L, LER-80-69-3L, NP-33-80-85, NUDOCS 8010070505
Download: ML19338F083 (2)

LER-1980-069, /03L-0:on 800902,during Diesel Generator 1-1 Oil Change,Bolt Fragment Discovered in Crankcase Sump.Caused by Loose Bolts in Idler Gear to Support Spider of Turbocharger Spring Drive Assembly.Modified Assembly Installed

Event date:
Report date:
3461980069R03 - NRC Website

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DOCKET NUMBER 68 63 EV ENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBA8LE CONSEQUENCES h

lal l (NP-33-80-85) On 9/2/80 maintenance personnel were performing an oil change on Diesel l l

i3; l G:nerator (DG) 1-1 and found a bolt fragment in the crankcase sump.

Further investi-l

- i.l l gation revealed the source to be a 5/8 inch bolt in the No. 2 (upper) idler gear of th4 651 l turbocharger spring loaded drive gear assembly. There was also surface damage to l

I: Ml lseveral teeth in the gear train assembly. Although.the DG l-1 had not actually failed {

l[: i 7 l l it had a condition which required repair to prevent further damage. There was no dan-l

Ia l lgrr to the public or station personnel. DG 1-2 was operable during this time.

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,,i 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECflVI ACYlONS h l l a l l The cause was the self-loosening of the four 5/8 inch bolts that hold the No. 2 idler l l gear to the support spider of the turbocharger spring drive assembly. One of the bolt $

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Under FCR 80-222, a new spring 2

1[.;3l l drive assembly was installed.

It was modified to provide positive locking of the l

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ST 5081.01 was successfully performed at 0455 hours0.00527 days <br />0.126 hours <br />7.523148e-4 weeks <br />1.731275e-4 months <br /> on September 19, 1980 l

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-85 DATE OF EVENT: September 2, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

Emergency Diesel Generator 1-1 idler gear bolt failure Conditions Prior to Occurrence: The unit was in Mode 5 with Power (MWT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence: On September 2, 1980 at 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br />, maintenance. personnel ware conducting an inspection of Emergency Diesel Generator (EDG) 1-1 as part of the preventive maintenance program. During the oil change, a 5/8 inch bolt and otner metal fragments were found in the crankcase sump.

Further investigation for the cource revealed that the bolt had been sheared from the No. 2 upper idler gear.

This grar is part of the turbocharger spring loaded drive gear assembly. There was also come surface damage to several gear teeth in the gear train.

Although EDG l-1 had not cetually failed, there was a condition that required corrective action to prevent addi-tional damage had it been run unrepaired. Therefore, it was declared inoperable.

Be-ing in Mode 5, the station did not enter the action statement of Technical Specification 3.8.1.2.

The technical specification requires only one EDC to be operable in this mode.

EDG l-2 was operable curing this time. This is being reported to document a component fcilure.

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D;signation of Apparent Cause of Occurrence: The four 5/8 inch bolts that hold the No. 2 idler gear to the support spider of the turbocharger spring drive assembly be-cIme loose. One of the bolts backed out far enough to be sheared off. This fragment traveldd through the gear train and caused some surface damage to several gear teeth.

The bolts that loosened did not have a. positive locking feature.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. Diesel Generator 1-2 was operable during this time.

Corrective Action

Under Facility Change Request 80-222, a new turbocharger spring drive assembly was installed. The drive assembly had undergone a design improvement by the vendor such that there is now positive locking of the bolts that had loosened.

To ensure the integrity of the slightly damaged gear train, the entire camshaft gear train was also replaced. Diesel Generator Monthly Test ST 5081.01, Section 6.1 was p:rformed following repairs.

It was declared operable at 0405 hours0.00469 days <br />0.113 hours <br />6.696429e-4 weeks <br />1.541025e-4 months <br /> on September 19, 1980.

EDG l-2 was also checked and although it did not have the loose bolt problem, it was also modified to provide positive locking of the bolts.

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Failure Data: There have been no previously reported similar failures.

j LER #80-069