ML20091H878

Applicant Exhibit A-137,consisting of 900807 Special Rept Re Facility Valid Diesel Generator Failures

ML20091H878
Person / Time
Site:	Vogtle
Issue date:	07/19/1995
From:	Hairston W GEORGIA POWER CO.
To:
References
OLA-3-A-137, NUDOCS 9508140312
Download: ML20091H878 (3)

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0FFICE OF SECRETARY

w. c. N.m.n. m DOCMEIlhG & SERVICE sen.or v<e Pres.een:

BRANCH Nvch Ope at ons ELV-01995 0535-Docket No.

50-424 50-425 U. S. Nuclear Regulatory Commission ATTN:

Document Control Desk Washington, D. C.

20555 Gentleman:

V0GTLE ELECTRIC GENERATING PLANT SPECIAL REPORT VALIO DIESEL GENERATOR FAILURES 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 three valid diesel generator failures.

Sincerely, id Y

Y W. G. Hairston, !!!

WGH,III/NJS/gm

Enclosure:

Special Report 1-90-05 xc:

Georoia Power Comoany Mr. C. K. McCoy Mr. G. Bockhold, Jr.

Mr. P. D. Rushton Mr. R. M. Odom

-NORMS U. S. Nuclear Reaulatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. T. A. Reed, Licensing Project Manager, NRR i

Mr. B. R. Bonser, Senior Resident Inspector, Vogtle NUkbR REGULhTORY COMMIShiON @(

a 1 -l37 Docket No. 50-424/425-OLA.3 EXHIBIT NO.

in the rnatter of Georaia Power Co. et af,, Voatte Units 1 & 2

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ENCLOSURE

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i V0GTLE ELECTRIC GENERATING PLANT - UNITS 1 AND 2 i

TECHNICAL SPECIFICATION SPECIAL REPORT l-90-05 VALID DIESEL GENERATOR FAILURES i

i i

A.

REQUIREMENT FOR REPORT l'

-This report is required in accordance with Technical Specification (TS) 4.8.1.1.3.

This specification requires that all diesel generator (DG) i failures, valid or non-valid, be reported to the Comission in a Special j

Report pursuant to TS 6.8.2.

I B.

DESCRIPTION OF EVENT q

L On 7-11-90, Diesel Generator (DG) 2A was being tested during a routine surveillance per procedure 14980-2, " Diesel Generator Operability Test".

i The right air start bank was isolated to allow testing of the left air start bank. The engine start button was pushed by the control room operator and the engine began to roll with starting air. According to i.

the local operator in the diesel room, the engine rolled twice and stopped. The DG was declared inoperable and the TS action statement was j.

initiated. The DG was unavailable for emergency operation for a period of 67 hours7.75463e-4 days <br />0.0186 hours <br />1.107804e-4 weeks <br />2.54935e-5 months <br /> and 49 minutes.

J During the review of this event, it was determined that similar events i

had occurred on 4-12-90 and 7-5-90.

These previous similar events had j

not been recognized as failures and therefore had not been reported as such. These events are described as follows:

l l

On 4-12-90, operators conducted a TS surveillance test of DG 2A per i-procedure 14980-2.

The manual start button was pushed, but no start occurred. Operators decided that the pushbutton had not been depressed j

j long enough and made another attempt which resulted in a successful i

start. On 7-5-90, a similar incident occurred on DG IB, and a successful i

start again resulted on the second attempt. Neither DG was considered to j

be unavailable for emergency operation as a result of these two events.

C.

CAUSE OF EVENT An investigation into the 1-11-90 event by utility and vendor personnel found that the starting ait valve pistons could stick in their cap assen611es due to inadequatt manufacturing tolerances. This condition was apparently the result of the initial manufacturing process which left insufficient-clearances between some of the pistons and caps. A failure to start would occur only after the engine had been shut down from a i

i previous run' and the engine stopped with a particular alignment of faulty 1

j air start valves and crankshaft position.

L i

i

1 ENCLOSURE V0GTLE ELECTRIC GENERATING PLANT - UNITS 1 AND 2 TECHNICAL SPECIFICATION SPECIAL REPORT 1-90-05 VALID DIESEL GENERATOR FAILURES On a non emergency manual start with the air start pilot valves malfunctioning, the initial burst of air was not adequate to start the engine. The burst of air was adequate to change the alignment of the crankshaft with respect to the faulty air start pilot valves so that any subsequent attempt to start the engine could be successful. This problem is now believed to have been the cause of the DG failures on 1-24-90 and 1-25-90, which were reported to the Comission on 2-19-90 as Special Report 2-90-02. On 7-19-90, the manufacturer of the valves submitted a 10 CFR 21 report to the Commission as a result of the above findings.

The failure of the DG operators to recognize the initial start attempts of 4-12-90 and 7-5-90 as DG failures is partially attributed to i

limitations of the simulator computer.

The simulator requires operators to hold the DG manual start pushbutton in order to have the proper control signals annunciate, creating the misconception that the l

pushbutton must remain depressed for a given period of time in order for t

a DG start to occur.

D.

CORRECTIVE ACTIONS l

1. The sixteen starting air valves on each of the four DG's were tested l

and polished where necessary to provide adequate clearance between the pistons and caps.

l

2. The appropriate maintenance procedures will be revised by the next 4'

refueling outages to require testing of the starting air valves to demonstrate freedom of movement following DG overhaul.

3. During shift briefings, operators were advised that the DG should start when the manual pushbutton is depressed, any failure to manually start is a reportable event, and such information should be relayed to l

the appropriate personnel so that a report can be initiated.

J

4. Operator training will be enhanced during the next training cycle to advise personnel that a DG start should occur without having to continue depressing the manual start pushbutton.

5. The DG 18 and 2A test frequency is currently once per 7 days in

-accordance with TS Table 4.8-1.

This frequency will be continued until 7 consecutive valid tests are completed with no more than one valid failure in the last 20 valid tests and/or no more than 4 valid failures in the last 100 valid tests. Up to and including the 7-5-90 valid failure, there have been a total of 6 valid failures in 79 valid rL tests of DGlB. Up to and including the 7-11-90 valid failure, there have been a total of 5 valid failures in 43 valid tests of DG2A.

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