05000334/LER-1979-028-01, /01T-0:on 790819,while Performing Manual Actions Following Reactor Trip,Operator Tripped Generator Output Breakers,Resulting in Underfrequency.Caused by Operator Error.Operator Reprimanded

/01T-0:on 790819,while Performing Manual Actions Following Reactor Trip,Operator Tripped Generator Output Breakers,Resulting in Underfrequency.Caused by Operator Error.Operator Reprimanded

ML19207B985
Person / Time
Site:	Beaver Valley
Issue date:	08/31/1979
From:	Werling J DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19207B944	List: 05000334/LER-1979-028-01, /01T-0:on 790819,while Performing Manual Actions Following Reactor Trip,Operator Tripped Generator Output Breakers,Resulting in Underfrequency.Caused by Operator Error.Operator Reprimanded
References
LER-79-028-01T, LER-79-28-1T, NUDOCS 7909060277
Download: ML19207B985 (1)

LER-1979-028, /01T-0:on 790819,while Performing Manual Actions Following Reactor Trip,Operator Tripped Generator Output Breakers,Resulting in Underfrequency.Caused by Operator Error.Operator Reprimanded

Event date:
Report date:
3341979028R01 - NRC Website

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8 60 63 OOCKETNOV8gR ca 69 EVENT OATE 74 15 REPORT DATE 80 EVENT DESCRIPTION AND PROBA8LE CONSEQUENCES h o 2 l At 1446 hours0.0167 days <br />0.402 hours <br />0.00239 weeks <br />5.50203e-4 months <br />, the reactor was manually tripped followine the trip of the IB Steam l

lol3ll Generator Feed Pump due to low NPSH. The operators performed the immediate manual l

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Attachment To LER 79-28/01T Beaver Valley Power Station Duquesne Light Company 2

Docket No. 50-334 At 1446 hours0.0167 days <br />0.402 hours <br />0.00239 weeks <br />5.50203e-4 months <br /> on August 19, 1979, the reactor was manually tripped from approximately 50% rated power following the trip of the 1B Main Feed Pump due to low net positive suction head. The 1A Condensate Pump was shutdown for cleaning of its strainer. The IB hain Feed Pump had just been started and the 1A Pump secured to investigate a high bearing temperature on the 1A Pump.

Upon initiation of the reactor trip, the operators performed the immediate manual actions following a reactor trip and loss of normal feedwater. An operator, thinking that the generator output breakers were taking too long to trip, manually tripped them prior to the automatic trip which normally occurs 30 seconds after the reactor / turbine trip.

Since the =ain generator was no longer tied to the system, frequency dropped on the LA and 1B 4KV Buses and all three reactor coolant pumps tripped on underfrequency (2 of 3 buses).

The 1C and ID 4KV Buses were tied into the system and did not experience the underfrequency condition. Thirty seconds after the turbine trip, the 1A and 1B Buses transferred to system power and the underfrequency condition cleared.

Fcur minutes after the reactor trip, the 1C Reactor Coolant Pump was started and forced flow returned to the reactor coolant system. All systems operated as designed and at no time was the health and safety of the public jeopardized.

The involved operator was reprimanded for his action. All Operations personnel will review the incident.

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