ML20083R718

AO 4-2-6:on 740125,reactor Brought Critical W/Control Rods Below Required Insertion Limit.Cause Under Investigation

ML20083R718
Person / Time
Site:	Indian Point
Issue date:	01/31/1974
From:	Cobean W CONSOLIDATED EDISON CO. OF NEW YORK, INC.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20083R713	List: ML20083R710 ML20083R718
References
AO-4-2-6, NUDOCS 8304040616
Download: ML20083R718 (1)

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I2 Qp Conichani Ldaon Comp ny of N:w York inc n 1%Jvta 4 Imng t . New Yo:L. N Y 10003 ("l , [-

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January 31, 1974 Re: Indian Point Unit No. 2 AF.C Docket ico . 50-247 Facility nyctnting Liconnn DPR-26 ,

A,0,-4-2-6 Mr. James P. O'Reilly, Director Regulatory operations, Region I U. 5, Atomic Energy Comd snion 631 Park Avenue F.ing of Prussia, Pennsylvania 19400 Doar Mr. O'Reilly,

'On January 25, 1974 the reactor was brought criti' cal preparatory to placing the plant back in service following completion of re-paire associated with 1.he November 13, 1973 feedwater line break incident. Criticality was achieved with the "C" bank of control rods 45 steps withdrawn from the core. The criticol positions of the control rods were approximately 27 steps below the inser-tion lisnite shown on Figure,3.10-1 of the Technical Specifica-ti on s . At the time of the occurrence thn reactor0coolant system pressure and temperature were 2235 psig. and 540 F respect.ively with all four reactor coolant pumpn in service and the baron con-centration won 1125 ppm boron, The 27 .stop diHorential repre-Gente a decrease in the required shutdown margin of about 0.26% <

reactivity, Minimum boron concentration required to maintain t.he required shutdown margin (Figure 3,10-3 of thn Technical Speci-ficatione) is calculated to be 770 ppm. Thereforo, the shutdown margin at the time of the occurrence wan considerably more than that required by Figure 3.10-3.

I We are investigating the causes of this occurrence and corrective action necessary to prevent recurrenco. Mr. Anthony Pasano of l

l your office was notified of this occurrence by telephone by Mr.

John Nar.epeace on January 30, 1974.

Very truly yours, r

8304040616 740208 PDR ADOCK 05000247 s* bi 4 k.7 h. ,

Warren R. Cobenn, Jr.g Manager S PDR Nuclear Power Generation cc: nr. achn F. 0 tcery n

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