ML20248L544

PNO-78-021:on 780205,w/unit Operating at 90 Percent Power Level,One Target Rock Rv Opened & Remained Open Until Reactor Pressure Reduced to 170 Psig.Licensee Plans to Replace Valve & Return to Power on 780207

ML20248L544
Person / Time
Site:	Browns Ferry
Issue date:	02/06/1978
From:	Klingler G, Nolan F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
References
PNO-78-021, PNO-78-21, NUDOCS 9806110223
Download: ML20248L544 (1)

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.A PRELIMINARY NOTIFICATION l

' February 6,1978 j PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-78-21 j This preliminary notification constitutes EARLY notice of an event of POSSI3LE safety or public interest significance. The information presented is as initially received Nithout verification or evaluation j and is basically all that is known by IE staff on this date. '

FACILITY: Tennessee Valley Authority Browns Ferry, Unit No. 2 Docket No. 50-260 -

Decatur, Alabama

SUBJECT:

PRIMARY SYSTEM BLOWDUWN At 8:00 a.m. on February 5, with the unit operating at 90 percent power level, one Target Rock relief valve opened and remained open until ,

reactor pressure reduced to 170 psig. The reactor was manually scrammed j at 8:28 a.m. when the suppression pool temperature reached 110 degrees +

Fahrenheit. Suppression pool cooling had been initiated by 8:20 a.m.

The licensee inspected the suppression pool and nothing unusu'al was '

-= -

. found. The cooldown rate of 110 degrees Fahrenheit / hour exceeded the Technical Specification limit of 100 degrees Fahrenheit / hour. A thermal transient analysis is in progress. The licensee plans to replace the

(, .-) valve and to return to power on February 7,1978. , l Media interest is not expected. A news release is being considered by the licensee. NRC actions are dependent on TVA's decision. The State of Alabama has been informed. 87 3 l

Region II (Atlanta) received notification of this occurrence by tele- d2_.

phone from the Assistant Plant Superintendent at 2:20 p.m. on February 5.

This information is current as of 11:00 a.m. on February 6.

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Contact:

GKlingler, IE x28019 FNolan, IE x28019 I Distribution: Transmitted H St M o3 Chairman ITsidrie Commissioner Bradford Commissioner Kennedy S. J. Chilk, SECY -

C. C. Kammerer CA Commissioner Gilinsky (For Distribution)

Transmitted: MNBB~2',O [ P Bldg'lJ,0 7 E. Volgena , IE L. V. Gossick, ED0 E. G. Case, NRR Region 2-l / /

S. H. Hanauer, EDO J. J. Fouchard, PA SS Bldg 2.;0 7 (MAIL)

R. Hartfield, MIPC C. V. Smith, NMSS T. J. McTiernan, 01A R. G. Ryan, OSP R. Minogue, SD H. K. Shapar, ELD j

t ' PRELIMINARY NOTIFICATION u..

9906110223 780206 l

! PDR 18sE PNO-78-21 PDR {

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