ML20086K437

Telecopy AO 74-37:on 740703,static Inverter Tripped on Restart of Recirculation Pump a Motor Generator Set.Cause Unknown.Occurrence Under Investigation

ML20086K437
Person / Time
Site:	Peach Bottom
Issue date:	07/05/1974
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086K415	List: ML20086K412 ML20086K421 ML20086K437
References
AO-74-37, NUDOCS 8401270106
Download: ML20086K437 (2)

Text

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• HTg OREPS P. O'Reiily, rector

3.g United States Atomic Ibergy Cominnion Directorate of Eegulatory Operatione ,

631 Park Avenue i Kira; cf Prussia, Fenanylva.nia 19406 j

Subject:

Abnormi Occurrence 24-Hour Notifiention confirming a. s, riciechmun a phone con.nrr.aison vits ur. nousia Capwton l A.E.C. Region 1RegulatoryOperationsOfficeenJuly3,1974

Reference:

License Nu-ber DPR-44, hand-an+ Number 1 TechnicalSpecificationTable35.D ReportNo.: 50-277-74-37

' ~

Report Date: July 5,1974 Occurrence Date: July 3,1974 Facility: Peach Bottee Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 IdentificationofOccurrence:

Tne static inverter which supplies a.c. power for the reactor core isolation

cooling system flow controller and system indication, tripped on the restart of the "A" recirculation pump 1!.G. set.

ConditionsPriortoOccurrence:

- Peactor had scrarned frcn approxicately 6&4 pcver. --

.= ..

DescriptionofOccurrence: .

Following a lov vacuu.i scra::, turbine trip, and fast hus transfer (which trips the recirculation pu::p 10 sets) as the "A" 10 set was teing restarted. ,

the 201C inverter tripped. Tne tripped inverter was i mediately identifiei

.viaannunciationandsuccessfullyreset.

. Designation of Apparent Cause of Occurrence:

E Ho cause of the tripr>in5 of the static inventer has been found. Tyc :,nput

= conditienswhichviiitriptheinverterareundervoltage(100V.D.C.)and 7 overvoltage (147 V.D.C.) at the inverter inpute. At the ti e of the trip f -.

the "A" 10 set was being started. It is believed that starting large totcr,s /,

cay change input D.C. voltage from the battery chargera enough to cause an4T 8401270106 740713 f --

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q q 7 g ,.n U* % s usGBla M A " M tN

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, - Analysis of Occurrence: .

- icas of the ststiOverter defeats the autor.atic Oe of operation of the reactor core isolation cooling system. Tne flev controller vill not decand rated flow. Turbine speed indication ic still available and tha c;erstor can uce the test circuit to bring the turbine up to rated flow speed and inject vater to the reactor. Because the tripping of the inverter was annunciated and quickly reset, this occurrence is of rinor cafety cignificece.

Corrective Action:

This occurrence is utill under invectiEation.

Failure Data:

Two other trippings of the TCIC inverter have been reported as A0-50-277-74-14 and AO- W 277-74-20.

Very truly yours,

,Z&";' & & M u. X{

W. T. Ullrich, Superintendent Peach Bottom Atomic Powcr Station i