ML20236L065

PNO-77-007:on 770109,CST While Operating at 91% Power Target Rock safety-relief Valve Opened & Did Not Reseat Until Pressure Decreased to 124 Psig.Reactor Manually Scrammed When Torus Temp Reached 110 Degrees F

ML20236L065
Person / Time
Site:	Hatch
Issue date:	01/10/1977
From:	Gower G, Roy G, Thompson D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PNO-77-007, PNO-77-7, NUDOCS 9807100201
Download: ML20236L065 (1)

Text

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' []> b h :l I$ PRELIMINARY NOTIFICATION b .

7 j 4 January 10, 1977 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-77-07 This prel'iminary notification constitutes EARLY notice of'an event of PCSSIBLE 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 thii.date.

l 2 Licensee: Georgia Power Company Hatch Unit No. 1 (DN 50-321)

SUBJECT:

INADVERTENT BLOWDOWN At 5:10 a.m. CST, on January 9, 1977, while operating at 91% power, a Target Rock safety-relief valve opened and did not reseat until the pressure

. decreased to 124 psig at 6:45 a.c.

The reactor was manually scrammed at 5:24 a.m. when the torus temperature reached 110 degrees F. Torus cooling was initiated prior to the scram ,

j ,

and the torus temperature eventually reached 135 degrees F. The reactor i '

was placed in cold shutdown and the safety-relief valve has een replaced.

e.

g The reactor vessel cooldown rate was exceeded during the event. The licensee is performing an analysis of the vessel cooldown rate prior to resuming i power operations.

j A press release is'n'ot planned by the licensee. NRC Region II, (Atlanta) received notification of this occurrence by telephone from the licensee at 1:40 p.m., EST, January 9, 1977.

Contac,t GCGower, IE x27261 GWRoy, IE x27261 DThompson, IE x27541 l

Distribution:

Chairman Rowden Commissioner Mason S. J. Chilk, SECY Commissioner Gilinsky C. C. Kammerer, CA G. F. Murphy, JCAE Commissioner Kennedy L. V. Gossick, EDO K. R. Chapman, NMSS R. G. Ryan, OSP S. H. Hanauer, EDO E. Volgenau, OIE J. A. Harris, PA /

B. C. Rusche, NRR H. K. Shapar, ELD T. J. McTiernan, OIA Transmitt'ed: PBldg /A*/o$ H St//.V.2 MNBB //.Y Luge

• PRELIMINARY NOTIFICATION

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9007100201 770110 V PDR I&E PNG-77-007 POR

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