05000324/LER-1981-073-03, /03L-0:on 810920,24 & 1007,diesel Generator 4 Did Not Attain Rated Speed in Required Time When Started.Caused by Intermittent Electrical Connection on Diesel Right Starting Air Bank Dc Solenoid Valve.Connection Repaired

/03L-0:on 810920,24 & 1007,diesel Generator 4 Did Not Attain Rated Speed in Required Time When Started.Caused by Intermittent Electrical Connection on Diesel Right Starting Air Bank Dc Solenoid Valve.Connection Repaired

ML20011A612
Person / Time
Site:	Brunswick
Issue date:	10/19/1981
From:	Pastva M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20011A608	List: 05000324/LER-1981-073, Forwards LER 81-073/03L-0 05000324/LER-1981-073-03, /03L-0:on 810920,24 & 1007,diesel Generator 4 Did Not Attain Rated Speed in Required Time When Started.Caused by Intermittent Electrical Connection on Diesel Right Starting Air Bank Dc Solenoid Valve.Connection Repaired
References
LER-81-073-03L-01, LER-81-73-3L-1, NUDOCS 8110290180
Download: ML20011A612 (2)

LER-1981-073, /03L-0:on 810920,24 & 1007,diesel Generator 4 Did Not Attain Rated Speed in Required Time When Started.Caused by Intermittent Electrical Connection on Diesel Right Starting Air Bank Dc Solenoid Valve.Connection Repaired

Event date:
Report date:
3241981073R03 - NRC Website

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NRC FORM h U.S. NUCLEAR REGULATORY COMMISSION (7 77) 4 LICENSEE EVENT REPORT 4

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60 61 DOCKET NUYBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h l o l 2 l lWhile performing periodic testing on No. 4 iiesel generator, the diesel started but didl 2

I O 13 l [not attain rated speed. On September 24,'1981 following an auto start of all four l

lo l4 l l diesel generators, it was observed that No. 4 diesel generator required 25 seconds to l

[ O I s i l attain rated speed. ' On October 7,1981, while performing required testing, No. 4 l

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h lil0llThe principal cause of these events was an intermittent electrical connection on the

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l i j i j l diesel right starting air bank DC solenoid valve, SS-SSV1,.model 2, which prevented thei l timely admission of fuel to the diesel. The electrical connection was repaired anci thel 3 7

l diesel was successfully tested, started and returned to service. Plant documentation l

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LER ATTACHMENT - RO #2-81-73 Facility: BSEP Unit No. 2 Event Date: September 20, 1981

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- On September 20, 1981, while performing Service Water and Service Water Lube System Operability Test, PT 24.1, when No. 4 diesel generator was started-to observe the opening of the diesel, Unit No.1 Service Water ' System supply valve,-

the diesel started but did not attain rated speed. The initial investigation of the event determined corrosion buildup in the valve body of the diesel left starting air b nk regulating valve PRV-786, Model 310-32, had prevented the' full admittance of starting air to the diesel, which resulted in the event. The valve was cleaned, reassembled snd tested for' proper operation. The diesel was then successfully test started and returned to normal standby ^ readiness..In addition, a Work Request was then submitte'd to inspect the diesel right starting air bank regulating valve, PRV-789 during the next scheduled maintenance on.No.

4 diesel generator, in order to ensure proper operation of the valve.

Prior to inspecting PRV-789 on September 24, 1981, following a main turbine trip resulting from a main generator load reject, all four diesel generators; auto started, but No. A required 25 seconds to attain rated speed. The initial investigation of this event revealed a corrosion buildup in the 789. valve, and' it was determined tae event had also occurred due to insufficient starting air

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pressure as was encountered during the September 20, 1981 event involving the

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PhV-786 pressure regulating valve. PRV-789 was then cleaned, reassembled and tested for proper operation. The diesel was then successfully started and' returned to normal standby readiness.

On October 7,1981, while performing required testing due to the removal cf No.

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1 diesel generator from service for maintenance, No. 4_ diesel generator started but failed to attain rated speed in the required <10 seconds.

This investigation of this event revealed a broken terminal ring on the solenoid operator to the diesel right starting air bank solenoid valve SV-SSV1.. It is believed the broken terminal ring permitted intermittent operation of the valve and is the fundamental cause of all three events.

During a " start" sequence of a diesel generator the diesel fuel regulating system receives an inithtl opening signal via the diesel right starting air bank.

After the dierel otarts, the normal hydraulic control of the. fuel regulating system is supplied by the pressure developed by the diesel driven-shaft oil pump.

It is believed that in each of the three events, the diesel' received sufficient starting air pressure to crank the diesel, but due to intermittent operation of the SV-SSV1 valve, the diesel fuel regulating system did not operate in a timely n.anner. In each case, the diesel would then start after sufficient engine cranking supplied enough hydraulic pressure to open the diesel fuel regulating system " fuel racks." The reason for the broken solenoid terminal lug which is fastened with a nut and is wrapped in electrical insulation could not be determined.

It is presently under consideration ;to -

evaluate the starting air moisture problems of the diesel generators' starting air systems.