ML19309H153

LER 80-018/03L-0:on 800407,during Mode 3 Operation,Both Emergency Feedwater Pumps Lost Feed Pump Section.Caused by Transient Loss of Offsite Power.Operator Isolated Startup & Blowdown Demineralizers as Source of Suction

ML19309H153
Person / Time
Site:	Arkansas Nuclear
Issue date:	05/05/1980
From:	Pendergraft R ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19309H151	List: ML19309H150 ML19309H153
References
LER-80-018-03L, LER-80-18-3L, NUDOCS 8005080524
Download: ML19309H153 (2)

Text

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HE, ORT oATE 80 P S 60 43 DoCKE T huMBEft 68 69 EvtNT DATE F4 PS EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h t o 121 l Durina Mode 3 operation, followina a loss of offsite oower transient. both ioi3i i Emergency Feedwater pumps lost feed pump suction. Loss of suction occurred o . I approximately 15 minutes after initial loss of offsite power. Loss od in ist i feed duration was less than one minute, therefore, Steam Generator Level I lo is i I was not noticably affected. There have been no similar occurrences. I o 2 i Reportable per T. S. 6.9.1.9(b) I o a I I

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EMERGENCY FEEDWATER PUMP LOSS OF SUCTION DESCRIPTION a

(Attachment to LER 50-368/80-018/03L-0)

The unit tripped from approximately 100% full power due to a loss of off-site power and 100% load rejection. Both emergency diesel generators came on automatically. The reactor established l natural circulation with both emergency feedwater pumps (2P7A and 2P7B) automatically feeding the steam generators. The emergency feedwater pumps were taking suction from the condensate storage tanks and the startup and blowdown demineralizer effluent. Approx-imately 15 minutes af ter the initial loss of off-site power, both emergency feedwater pumps lost suction. Operators isolated the startup and blowdown demineralizers as a source of pump suction.

Emergency feedwater flow was reestablished in less than one minute.

Later investigation revealed the emergency feedwater pump suction had flashed to steam due to the feedwater train flashing and forcing hot water back through the startup and blowdown tanks (2T94A/B) and into the feedwater pump suction.

To prevent this recurrence, the operating procedures have been changed to require isolating the startup and blowdown effluent as a source of emergency feedwater suction prior to increasing power above 5% full power.