ML20084K494

Ao:On 740910,during Routine Surveillance,Operator Failed to Receive B Main Steam Line High Radiation Scram & Isolation Alarm.Caused by Operator Error.Time Delay Kit Will Be Installed.Operator Procedures Will Be Revised

ML20084K494
Person / Time
Site:	Dresden
Issue date:	09/19/1974
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20084K496	List: ML20084K494 ML20084K569 ML20084K576
References
676-74, NUDOCS 8305190443
Download: ML20084K494 (2)

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- T . o'- g ya One First n u Plaza. Chjc3 0.pnois dy; Address to: Post Office Bcx 767

% Chicago, licncis 60690 - l BBS Ltr.#676-74 Dresden Nuclear Power Station R. R. #1 ,

Morris, Illinois 60450 I September 19, 1974 l

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v Mr. James G. Keppler, Regional Director 50-237 ,M /4-/-7 Y '

Directorate of Regulatory Operations-Region III . ;!, g, 3 ,

U. S. Atomic Energy Coc=iosion - 1. '  : .i 799 Roosovolt Road '

Glen Ellyn, Illinoin 60137 M .

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SUBJECTS . REPORT OF ABNORMAL OCCURRD!CE PER SECTION 6.6.B 0F THE TECMICAL SPECIFICATIONS.

MAIN STFE4 LINE HI RADIATION MONITOR "B" PAILURE TO INDICATE A HI-HI ALARM AND TRIP LURING ROUTINE SURVEILLANCE.

References:

1) Regulatory Guide 1.16 Rev.1 Appendix A

2) Notification of Region III of AEC Regulatory Operations Telephone Mr. F. Maura, 0915 houro on September 10, 1974 Telegram: Mr. J. Keppler, 1335 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.079675e-4 months <br /> on September 10, 1974

3) Drawing Number: Tech Manual GEK-13958 Drawing 104R798 Rev.9 Report Nu:r;ber: 50-237 Report Date September 19, 1974 .

Occurrence Date: September 10, 1974 Facility: Dresden Nuclear Power Station, Morris, Illinois IDD7PIFICATION OF OCCURRDiCE While performing routine surveillance, " Main Steam Line Radiation Monitor-Scram and Isolation Functional Teat" on Dresden Unit #2 Monitor "B", the-reactor operator reported what was thought to be a. failure to receive the "B" main' steam line high radiation scram and isolation alam.

CONDITIONS PRIOR TO OCCURRDER Unit #2 was operating in a steady state plcnt condition of 676 We. Routino

. surveillance " Main Steam Line Radiation Monitor Scram and Isolation Fbnction-al Test" on monitor "B" was in progress.-

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/~} Saptember 19, 1974

.Mr. Jam n G. K$ u r ,

DESCRIPTION OP OCCURRENCE At 0245 hours0.00284 days <br />0.0681 hours <br />4.050926e-4 weeks <br />9.32225e-5 months <br /> on September lo, 1974, while performing routine surveillance testing of Unit #2 main steam line high radiation monitor "B", the reactor

- operator reported uhat was thought to be a failure to receive the "B" min steam lino high radiation ceram and isolation alarm. Monitor "B" was de-energized and repair of the monitor requested. The instrument mechanic checked the monitor at approximately 0345 on September lo, 1974 and found the monitor to be operating catisfactorily.

DESIGNATION OF APPAREITF CAUSE OF OCCURRENCE (Deficient Operating Procedures)

The operator did not hold the " trip test (depressed)" cwitch S6 in the depressed position for a period long enough to allow the electrical charge accumulated across time delay capacitor "C51" to decay, thereby de-energizing the trip circuit B relay K6 and activating the "B" main steam line high radiation scram and isolation alarm.

ANALYSIS OP OCCURRENCE A time dolay kit was previously installed on the "B" monitor in accordance with field disposition instruction, NBEA, IG2-2-74-76. I!ain steam line high radiation monitors "A", "C" and "D" do not, ao yet, have the timo delay kit installed. The reactor operator did not realize tho time delay kit was installed on the "B" monitor.

During the period of de-energization of the monitor, the safety of the plant personnel or the general public was not jeopardized because this unit auton:atically trips one reactor protection channel. Thus any signal from the other channel will initiate a plant shutdown.

CORRECTIVE ACTION The time delay kit will be installed in all the main steam line hi radiation monitors. A procedure change has been made instructing the operator to hold the switch for a specified time period.

PAILURE DATA This is the first occurrence of this type.

Sincerely,

.'B. Stephenson Superintendent BBS: WEE:do

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