ML20151U429

PNO-77-077:on 770504,during Shutdown Margin Test on Listed Reactor Refueling Outage,Short Reactor Period Occurred Before Power Increase Terminated by Inserting Control Rods

ML20151U429
Person / Time
Site:	Quad Cities
Issue date:	05/10/1977
From:	Dreher F, Roy G, Thompson D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PNO-77-077, PNO-77-77, NUDOCS 9809110004
Download: ML20151U429 (1)

Text

g4 m) J o L y QJN PRELIMINARY NOTIFICATION ,

j l

May lu, 1977 i

/ PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-77-77 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 thi_s date.

• Facility: Cummonwealth Edison Company, Quad-Cities Unit No.1 (Docket No. 50-254), Cordova, IL -

Subject:

REACTOR PERIOD LESS THAN 5 SECONDS DURING SHUTDOWN MARGIN TESTG During a shutdown margin test on May 4,1977, following a reactor refueling outage, a short reactor period occured before the power increase was termi-nated by inserting control rods. The cause of the event was due to not following the procedure for the sequence of withdrawal of the control rods involved. A short blip was observed on the Source Range Monitors.

The operator immediately terminated the event by inserting control rods. At the time, the licensee did not believe that a short period had occurred.

After subsequent evaluations, the licensee attempted to take additional data on May 7, 1977. At that time, an error in judgement was made by the Nuclear-Engineer in allowing -continuous withdrawal of ~a' control' rod during i

the approach.to the critical rod configuration. Again a short blip was noted on the Source Range Monitors. A strongly reactive control rod was reinserted and a seventy-five (75) second period was achieved. . .

Based on calculationr. of rod worth the licensee has estimated that the l period on both occurrences was less than 5 seconds.

A Region III (Chicago) inspector is being dispatched to the site.

No press release is planned by the licensee or Region III (Chicago).

The states of Illinois and Iowa are being informed of this event.

This PN is being issued because the occurrence is considered to be unusual.,

, and inay have generic implications.

n Region III (Chicago) received notification of this occurrence by tele-phone from the Plant Superintendent at 2:00 p.m., on May 8, 1977.

you 3

Contact:

FADreher, IE x27261 GWRoy, IE x27261 DThompson, IE x27541 in o # .

Distribution: Transmitted H St /J .*/d $8 N Chairman Rowden C. C. Kammerer, CA G. F. Murphy, JCAE 4 N Commissioner Kennedy S. J. Chilk, SECY H. H. Whiteside, SCNR Commissioner Gilinsky ab$}{ j pansmitted: HNBB'% .*O

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P Bldg / b ? IS H. R. Myers, HCEE SS Bldg .8 ' - / .* /

w L. V. Gossick, EDO E. G. Case, NRR C. V. Smith, NMSS

• ' S. H. Hanauer, EDO J. A. Harris, PA W. G. Mcdonald, MIPC Luge (MAIL)

R. G. Ryan' OSP E. Volge u v e u. - -

ma T. J. McTiernan, OIA Region "pu, IE'*"Ii3