ML20151M769

Special Rept:On 880602 & 24,diesel Generator 2B Started for Emergency Safeguards Feature Test,Terminated Due to Oil Cooler Leak.Caused by Failure of Tube Sheet to Shell Asbestos Gasket.Gasket Replaced & Oil Cooler Reassembled

ML20151M769
Person / Time
Site:	Mcguire
Issue date:	07/22/1988
From:	Tucker H DUKE POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8808050341
Download: ML20151M769 (2)

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• - DUKE POWER GoMiwxy P.O. ISOX G3180 l CIIAMLOTTE, N.O. 20242 I IIAL 11. TUCKER ' rei.nreioxe I ma reemment (704) 373-4531 NtTLE45 PRODE;CTION July 22, 1988 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. ~20555

Subject:

McGuire Nuclear Station, Unit 2 Docket No. 50-370 Technical Specification 4.8.1.1.3 and 6.9.2 Gentlemen: .

Pursuant to Technical Specification (T.S.) 6.9.2 as specified by T.S. 4.8.1.1.3, find attached a special report concerning Diesel Generator (D/G) 2B that was due to be submitted July 5,1988, but was delayed due to unresolved concerns.

Should there be any questions concerning this matter, please contact S.E. LeRoy at (704) 373-6233.

Very truly yours, f/JJ^

Hal B. Tucker SEL/303/ bhp xc: Dr. J. Nelson Grace, Mr. W.T. Orders Regional Administrator NRC Resident Inspector U.S. Nuclear Regulatory Commission McGuire Nuclear Station Region II 101 Marietta St., NW, Suite 2900 INPO Records Center Atlanta, Georgia 30323 Suite 1500 1100 circle 75 Parkway Mr. Darl Hood Atlanta, GA 30339 Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555

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8908050341 880722

/4M PDR ADOCK 05000370 /' \

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..* DUKE POWER COMPANY McGuire Nuclear Station Diesel Generator 2B Special Report On June 2, 1988 at 2130, while Unit 2 was operating in Mode 5, Cold Shutdown, Diesel Generator (D/G) 2B was started for _an Emergency Safeguards Feature (ESP) test (start attempt # 62 5) . The D/G run was terminated 21 minutes later due to a lube oil cooler leak, and was declared a valid failure. This failurc was the seventh valid failure in the last 100 valid test starts on the Unit 2 D/G sets.

The oil leak sprayed approximately 100 gallons of lube oil into the D/G room on the diesel engine around the turbo charger. D/G 2B and the D/G room were thoroughly washed following the incident to remove all residual oil.

Additior. ally, the area fire protection systems were operable throughout the incident.

The lube oil cooler, model CBP, manufactured by American Standard, was disassembled and repaired per the Diesel Engine Lube Oil Cooler Corrective Maintenance procedure. The csuse of the lube oil leak was determined to be the failure of the tube sheet to shell asbestos gasket which was torn on the stationary end during the last installation. The gasket was replaced and the lube oil cooler was reassembled.

At this time the 18 month periodic maintenance activities were performed on D/G 2B.

On June 24, 1988 at 1019 with Unit 2 in No Mode (fuel removed from reactor core), D/G 2B was started (start attempt No. 626) for break in runs. After 10 minutes of operation, the lube oil cooler developed a small leak on the tube sheet to shell gasket at the stationary end. Maintenance again disassembled the lube oil cooler and determined that the gasket previously installed had been torn during installation. The failure of the gasket was due to misalignment during installation because the gasket dropped out of position during the torque sequence performed on the tube to shell flange.

The asbestos gasket supplied by the manufacturer was replaced with a non-asbestos type gasket material slightly modified to ensure the flange was completely covered during installation. The new gasket was cut to fit the entire flange instead of just the incide area as the old gasket did.

The Diesel Engine Lube Oil Cooler Corrective Maintenance precedure has been changed to increase the torque from 360 inch pounds to 450 inch pounds on the flanges to ensure adequate gasket crush. Covers are also being installed on all D/G lube oil line flanges which will direct the oil spray to the floor, should this type leak occur again.

On June 24, 1988 at 2132 with Unit 2 in No Mode, D/G 2B was successfully started (start attempt No. 627) to continue break in runs, and was declared operable.

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