L-85-146, Special Rept:On 850308,diesel Driven Fire Pump Declared Out of Svc as Result of Inoperable Immersion Heater in Diesel Cooling Sys.Caused by Defective Thermostat Switch.Immersion Heater Assembly Replaced

Special Rept:On 850308,diesel Driven Fire Pump Declared Out of Svc as Result of Inoperable Immersion Heater in Diesel Cooling Sys.Caused by Defective Thermostat Switch.Immersion Heater Assembly Replaced

ML20115J737
Person / Time
Site:	Turkey Point
Issue date:	04/08/1985
From:	Williams J FLORIDA POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
85-146, L-85-146, L-85-16, L-85-46, NUDOCS 8504240090
Download: ML20115J737 (3)

Text

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FLORIDA POWER & LIGHT COMPANY APR 1 O 1925 L-85-146 Dr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20535

Dear Dr. Denton:

Re: Special Report Turkey Point Units 3 and 4 Date of Event: March 8,1985 Technical Specification 6.9.3 Diesel Driven Fire Pump Outage The attached Special Report is being submitted in accordance with Technical Specification 6.9.3 to provide 30-day notification of the subject occurrence.

Very truly yours, 4

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3. W. Wi ms,Jr.

Group Vice President Nuclear Energy 3WW/SAV/js Attachment cc: Dr. 3. Nelson Grace Harold F. Reis, Esquire PNS-LI-85-145v h

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PEOPLE. . SERVING PEOPLE

SPECIAL REPORT APRIL 8,1985 DIESEL DRIVEN FIRE PUMP OUTAGE

Purpose:

On March 8, 1985, the diesel driven fire pump, serving the fire protection requirements of the Turkey Point Nuclear Units 3 and 4, exceeded the 7 day outage reportability limitations established in Technical Specification 3.14.2. In accordance with the reporting requirements of Technical Specifications, this special report on the outage of the diesel driven fire pump is generated to appraise the NRC. The health and safety of the public were not affected as a result of this

' event.

Event:

At 10:33 a.m., on March 1,1985, the diesel driven fire pump was declared out of service as the result of an inoperable immersion heater in the diesel's cooling system. This heater maintains the cooling system and engine block at an elevated temperature, while the engine is not running, to ensure more reliable starts. He diesel fire pump was returned to service at 7:50 p.m., on March 8,1985, after post-maintenance testing demonstrated the diesel fire pump to be operable. During the outage of the diesel driven pump, the normal electric motor driven fire pump was operational and could have supplied design flows. In addition, the diesel engine was mechanically functional during this outage and the diesel driven pump could have been used to supply water to the fire protection water system header.

Cause and Corrective Actions:

The cause of the immersion heater failure was a defective thermostat switch which failed such that power was continuously applied to the heater, burning out the heater element. Upon discovery of the failed immersion heater on March 1,1985, a replacement heater assembly, including the thermostat switch, was ordered from the manufacturer. This replacement arrived several days later and was installed on the engine. Subsequent pump testing revealed a minor leak around the threads of a small schedule 40 welded seam pipe, which supplies cooling water to the heat exchanger for the closed cycle engine cooling system. The affected section of piping was fabricated onsite and installe~d. The cause of the piping leakage was a minor piping wall defect underneath the threads.

Subsequent post maintenance testing was initiated at 2:30 p.m., on March 7,1985.

While the post-maintenance test verified the proper operation of the immersion heater / thermostat assembly, this test revealed that the engine DC ammeter, which measures the current output of the engine alternator, was indicating a negative current. A subsequent maintenance investigation was initiated on March 8,1985, to establish the cause of the negative DC ammeter readings. Bis investigation revealed that the leads to the ammeter were reversed, and that the alternator was operating satisfactorily with a positive current output to the electrical equipment on the diesel engine.

(T14:4)

4 Special Report April 8,1985 Diesel Driven Fire Pump Outage Page 2 An evaluation of the significance of the ammeter readings to the safe operation of the engine was conducted. The conclusion was that the ammeter's reversed leads were not significant to the safe operation of the diesel engine; and the diesel engine and the connected fire pump were declared operable at 7:50 p.m., on March 8,1985, which was 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> and 17 minutes past the 7 day reporting requirements of Technical Specification 3.14.2.

Corrective Action Summary:

1) Replaced the immersion heater assembly and integral thermostat switch.

2) Replaced a short section of one inch diameter water cooling system piping.

3) An engineering investigation into the reversed engine DC ammeter wiring has been completed and the wiring connections to the DC ammeter will be changed so that current output from the alternator will be indicated in the upscale (charging) direction.

(T14:4)