ML20151U865

PNO-77-065:on 770421,reactor Scram Occurred During Full Power Operation.Caused by Technicians Working on Reactor Water Level Logic Instrumentation.No Press Relsease Planned

ML20151U865
Person / Time
Site:	Browns Ferry
Issue date:	04/22/1977
From:	Gower G, Roy G, Thompson D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PNO-77-065, PNO-77-65, NUDOCS 9809110206
Download: ML20151U865 (1)

Text

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g,_gc PRELIMINARY NOTIFlCATION k c F. g ,q April 22, 1977 -

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-77-65 This preliminary notification constitutes EARLY notice of an event of POSSIBLE safety br 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.

Facility: TennesseeValleyAuthority(DN50-259)

Brown Ferry Unit No.1

Subject:

PRIMARY SYSTEM BLOWDOWN At 12:40 p.m. 4/21 during full power operation a reactor scram occurred which may have been caused by technicians who were working on the reactor water level logic instrumentation. Four Target Rock relief l valves opened to relieve the initial pressure increase incident to the scram and one of these valves failed to reseat. Reactor pressure decreased to approximately 300 psig in 5 to 10 minutes when the valve reseated. Reactor pressure increased to about 700 psig and the relief valve agein opened to again reduce pressure to about 300 psig.

l The torus water temperature reached about 120' degrees F. TVA plans..to '

visually inspect inside the torus above water level. The 100 degrees per

'. hour technical specification cooldown rate was slightiv exceedad.

! The re, lief valve will be replaced. TVA expects to return to operation l.I t ',

during the afternoon of 4/23.

g A press release is not planned by the licensee. NRC does not plan to issue a press release.

NRC, Region II, (Atlanta) received notification of this occurrence from the Assistant Plant Superintendent by telephone at 10:20 a.m. on 4/22.

Contact:

GCGower, IE x27261 GWRoy, IE x27261 DThompson, IE x27541 Distribution: Transmitted H StM VO Chairman Rowden C. C. Kammerer, CA G. F. Murphy, JCAE Commissioner Gilinsky S. J. Chilk, SECY H. H. Whiteside, SCNR H. R. Myers, HCEE -

Transniitted: MNBBY/,W/; PBldgJ.'N; SS Bldg 3l V.'~;

L. V. Gossick, EDO E. G. Case, NRR C. V. Smith, NMSS S. H. Hanauer, ED0 H. K. Shapar, ELD c/

J. A. Harris, PA W. G. Mcdonald, MIPC Luge (mail); E. Volgenau IE y R. G. Ryan, OSP T. J. McTiernan, OIA Region i,, 31 V7; 3)( 0 PRELIMINARY NOTIFICATION

.Y Y

9009110206 770422 PDR I8eE ~~

PNO-77-065 PDR

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