ELV-03601, Rev 1 to Special Rept 2-91-1:on 910521,mechanical Governor Oil Level Appeared Low After Dropping to Bottom of Sight Glass Due to Small Span of Governor Oil Level Sight Glass. Change Made to DG Standby Status Mode Checklist

Rev 1 to Special Rept 2-91-1:on 910521,mechanical Governor Oil Level Appeared Low After Dropping to Bottom of Sight Glass Due to Small Span of Governor Oil Level Sight Glass. Change Made to DG Standby Status Mode Checklist

ML20096D301
Person / Time
Site:	Vogtle
Issue date:	05/11/1992
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
2-91-1, ELV-03601, ELV-3601, NUDOCS 9205150199
Download: ML20096D301 (3)

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(3 ,p, g fa' + s * ,e flay 11, 1992 ELV-03601 001397 Docket No. 50-425 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen:

V0GTLE ELECTRIC GENERATING PLANT SPECIAL REPORT INVALID DIESEL GENERATOR FAILVE 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 submitted a Special Report dated June 17, 1991, (ELV 02900) concerning an invalid diesel generator failure. Regulatory Guide 1.108 states that the report should identify the nth failure in the last 100 valid tests and our Diesel Start Logs and Technical Soecifications use this terminology also. However, the referenced report incorrectly stated that diesel generator 2A had experienced 6 valid failures in the last 100 valid tests when, in fact, diesel generator 2A had only experienced 90 valid tests as of the date of the failure which was the subject of this report. The enclosed revised report corrects this error and updates the status of corrective action No. 2 which was outstanding at the t %e of the original report.

Sincerely, (Bit 'd C. K. McCoy CKM/NJS/gmb

Enclosure:

Special Report 2-91-1, Revision 1 xc: Georaia Power Comoany Mr. W. B. Shipman Mr. M. Sheibani NORMS U. S. Nuclear Reoulatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. D. S. Hood, Licensing Project Manager, NRR Mr. B. R. Bonser, Senior Resident Inspector, Vogtle 920 go,5150199 u ._

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I V0GTLE ELECTRIC GENERATING PLANT - UNIT 2 TECHNICAL SPECIFICATION SPECIAL REPORT 2-91-1, REVISION 1 INVALIE IESEL CENERATOR FATlURE A. REQUIREMENT FOR REPORT This report is required in accordance with the Vogtle Electric Generating Plant Technical Specifications (TS), section 4.8.1.1.3, which requires all diesel generator (DG) failures, valid er nonvalid, be reported to the Commission in a Special Report pursuant to TS 6.8.2.

B. DESCRIPTION OF INVALID FAILURE OF DIESEL GENERATOR 2A On May 21, 1991, at 0943 CDT, DG 2A was successfully started for a combined weekly /6-month surveillance test per TS req irements. Shortly into the test, an operator noticed that the mechanical governor oil level appeared low since it had dropred to the bottom of the sight glass. As a precautionary measure, the 00 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 wt. noticed at the governor drain connection. The co1nection was tightened, dnd 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 cl1 level appeared to drop low after the OG 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 goverror 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 scall oil leak which apparently caused the initial governor oil level to be slightly below .

normal.

J D. ANALYSIS'0F 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. As of the failure date, DG 2A had I experienced 1 valid failure in the last 20 valid tests and 6 valid failures

. in the last 90 valid tests. Therefore, the test frequency for DG 2A remained I 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 was made to require l

. the governor oil level to be verified as full, or ne?r full, as indicated by the sight glass.

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