ML20084F556

AO 250-75-6:on 750623,during Rotation of Operating Equipment,Intake Cooling Water Pump 3A Malfunctioned.Rept Incomplete

ML20084F556
Person / Time
Site:	Turkey Point
Issue date:	08/01/1975
From:	FLORIDA POWER & LIGHT CO.
To:	Rusche B Office of Nuclear Reactor Regulation
References
AO-250-75-6, NUDOCS 8304210169
Download: ML20084F556 (1)

Text

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FLORIDA POWER & LIGHT COMPANY August 1, 1975 Mr. Benard C. Rusche, Director

• Office of Nuclear Reactor Regulation '

U. S. Nuclear Regulatory Commission Washington, D. C. 20555 fl!):. ; '-

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Dear Mr. Rusche:

t 1 r ABNORMAL OCCURRENCE NO. 250-75-6 '

TURKEY POINT UNIT NO. 3 .

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DATE OF OCCURRENCE: JULY 23, 1975 MALFUNCTION OF 3A INTAKE COOLING WATER PUMP BREAKER A. CONDITIONS PRIOR TO OCCURRENCE Unit No. 3 reactor was critical at about 1% rated power.

Normal feedwater had been secured so that feedwater pump suction strainers could be cleaned. Steam generator water level was being maintained by auxiliary feedwater pumps. l B. DESCRIPTION OF OCCURRENCE Operating personnel were conducting a routine rotation of operating equipment. At about 2:30 a.m. on July 23, 1975, they attempted to start the 3A Intake Cooling Water Pump.

The starting current, as observed in the Control Room, ap-peared normal at first but then dropped to zero, indicating that the breaker closed but then tripped open. .

C. DESIGNATION OF APPARENT CAUSE OF OCCURRENCE

1. Functional description of breaker trip mechanism:

After a breaker trip has occurred, a spring, called the trip latch return spring, exerts a rotational force on the trip latch shaft which causes the latch to rotate back to the position it occupied prior to the trip.

Then, when the next attempt is made to close the breaker, the trip latch will be in position to seat against the trip assembly and prevent the breaker from tripping unless a valid trip signal is received. If the trip latch is improperly repositioned and a closure attempt is made, the breaker may close but will then trip.

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