ML20236K919

PNO-77-018:on 770131,while Operating at 90% Power Target Rock safety-relief Valve Opened & Did Not Reseat Until Pressure Decreased to 87 Psig.Reactor Placed in Cold Shutdown & safety-relief Valve Will Be Replaced

ML20236K919
Person / Time
Site:	Hatch
Issue date:	02/01/1977
From:	Gower G, Roy G, Thompson D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PNO-77-018, PNO-77-18, NUDOCS 9807100140
Download: ML20236K919 (1)

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t PRELININARYNOTIFICATION N:

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Yebruary 1, 1977 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE-PNO-77-18

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This preliminary notification constitutes EARLY notice of an event of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by IE staff on this date.

j Facility: Georgia Power Company (.GPC)

Hatch Unit No.1 (DN-50-321) ii-1+

Subject:

INADVERTENT BLOWDOWN l

.At 4:20 p.m. CST, on January 31, 1977, while operating at 90% power, a

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' Target Rock safety-relief valve opened and did not reseat until the

, pressure decreased to 87 psig at 7:15 p.m.

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The reactor was manually scrammed at 5:20 p.m. when the torus temperature reached 110 degrees F.

Torus cooling was initiated prior to the scram I

i and the torus temperature eventually reached 165 degrees F.

Inspecticus j

external to the torus have been completed.. No abnormality was found.

l The reactor was placed in cold shutdown and the safety-relicf valve will l

be replaced. The reactor vespel cooldown rate was exceeded during the event. GPC is performing an analysis of the vessel cooldown rate prior to resuming power operation.

A press release is not planned by the licensee. NRC, Region II (Atlanta)

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received notification of this occurrence by telephone from the IE:II inspector onsite at 2:30 p.m., EST, February 1, 1977.

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Contact:

GCGower, IE x27261 GWRoy IE x27261 DThompson, IE-x27541 l

Distribu': ion:

Chairman Rowden' Commissioner Kennedy S. J. Chilk, SECT l

Commissioner Gilinsky C. C. Kammerer, CA G. F. Murphy, JCAE L. V. Gossick, EDO K. R. Chapman, NMSS R. G. Ryan, OSP S. H. Hanauer, EDO E. Volgenau, OIE J. A. Harris, PA E. C. Rusche, NRR H. K. Shapar, ELD T. J. McTiernan, OIA Transmitted: P31dg Q H St. W

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PRELIMINARY NOTIFICATION OD h

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9807100140 770201

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POR I&E PNO-77-018 PDR

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