ELV-02900, Special Rept 2-91-1:on 910521,operator Noticed Mechanical Governor Oil Level Low When Level Dropped to Bottom of Sight Glass.Caused by Small Span of Governor Oil Level Sight Glass.Governor Drain Connection Tightened

Special Rept 2-91-1:on 910521,operator Noticed Mechanical Governor Oil Level Low When Level Dropped to Bottom of Sight Glass.Caused by Small Span of Governor Oil Level Sight Glass.Governor Drain Connection Tightened

ML20081J668
Person / Time
Site:	Vogtle
Issue date:	06/17/1991
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
2-91-1, ELV-02900, ELV-2900, NUDOCS 9106240097
Download: ML20081J668 (3)

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e-o , , . s . . . n.4 ,,m,,,s,. 2 , ,y o June 17, 1991 ELV-02900 1018 Docket No. 50-425 U. S. Nuclear Regulatory Conanission ATTH: Document Control Desk Washington, D. C. 20555 Gentlemen:

V0GTLE ELEC1RIC GENERATING PLANT SPECIAL REPORT INVAllD_plESEL GENERATOR FAILURE In accordance with the requirements of the Vogtle Electric Generating Plant Technical Specifications, Sections 4.8.1.1.3 and 6.8.2, Georgia Power Company hereby submits the enclosed Special Report concerning an invalid diesel generator failure.

Sincerely, C. K. ticCoy CKH/NJS/gmb ,

Enclosure:

Special Report 2-91-1 xc: Georaia Power Company Mr. W. B. Shipman Mr. P. D. Rushton Mr. M. Sheibani NORMS U. S. Nuclear Reggiatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. D. S. Hood, Licensing Project Manager, NRR Hr. B. R. Bonser, Senior Resident Inspector, Vogtle 9106240097 970617 PDR s

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I V0G1LE ELECTRIC GENERATING PLANT - UNIT 2 TECHNICAL SPECIFICATION SPECIAL REPORT 2-91-1 INVAllD DIESEL GENERATOR FAILURE A. REQUIREMENT FOR REPORT 1

This report is required in accordance with the Vogtle Electric Generating l Plant Technical Specifications (TS), section 4.8.1.1.3, which requires all l diesel generator (DG) failures, valid or nonvalid, be reported to the I Commission in a Special Report pursuant to TS 6.8.2.

B. DESCRIPTION OF INVAllD FAILURE OF DIESEL GENERATOR 2A On 5-21-91 at 0943 CDT, DG 2A was successfully started for a combined weekly /6-month surveillance test per TS requirements. Shortly into the test, an. operator noticed that the mechanical governor oil level appeared low since it had dropped to the bottom of the sight glass. As a precautionary measure, the DG was shut down at 0953 CDT. After the DG was shut down, an investigation found that the governor oil level returned to slightly above centerline indication. While this indicated that the governor oil level was acceptable, a visual inspection of the governor was performed, and after the governor base was wiped clean, a small drop of oil was noticed at the governor drain connection. The connection was tightened, and about I to 2 ounces of oil were added to bring the sight glass indication up to full. The situation was discussed with the system engineer and it was determined that due to the sight glass having a small span, the governor oil level appeared to drop low after the DG was started, even though the oil level had actually remained acceptable. Apparently this concern has not been addressed previously since governor oil level is normally at or near full with the DG in standby and then drops to near the centerline of the sight glass after the DG is started, in this case, possibly due to the small oil leak, governor oil level had initially been slightly below normal. At 1659 CDT, DG 2A was restarted and the surveillance test was completed without incident.

C. CAUSE OF EVENT The root cause of the event was the small span of the governor oil level sight glass. A contributing cause was that the DG standby status mode checklist does not require the governor oil level to be verified as full but rather requires the governor oil level to be above the centerline of the sight glass. An additional contributing cause was the small oil leak which apparently caused the initial governor oil level to be slightly below normal.

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D. ANALYSIS Of EVENT Diesel generator 2A was continuously available for emergency service '

throughout the event. This event is classified as an invalid failure per Regulatory Guide 1.108, section C.2.e. For DG 2A, there has been 1 valid failure in the last 20 valid tests and 6 valid failures in the last 100 valid tests. Therefore, the test frequency for DG 2A remains at once per 7 days in accordance with the requirements of TS table 4.8-1.

E. CORRECTIVE ACTIONS

1. The governor drain connection was tightened, and oil was added to bring the sight glass indication up to full.

2. A change to the DG standby status mode checklist will be made by 7-15-91 to require the governor oil level to be verified as full, or near full, as indicated by the sight glass.

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