ML20133G857

Provides Justification for Comeds Decision to Increase Commitment for Max Number of Days of Operation of Unit 1 Cycle 8.Increase Will Improve Detection Threshold for Top of Tube Sheet Circumferential Indications

ML20133G857
Person / Time
Site:	Byron
Issue date:	01/07/1997
From:	Hosmer J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9701160190
Download: ML20133G857 (2)

Text

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Commonwralth likson Company I 600 Opus I'larc Downers Grosc. 11.60515 January 7,1997 U.S. Nuclear Regulatory Commission Washington, D.C 20555 Attention:

NRC Document Control Desk

Subject:

Byron Unit 1 Cycle Length NRC Docket Number 50:454

References:

1. J. Hosmer letter.to the Nuclear Regulatory Commission dated December 20,1996, transmitting Information Pertaining to Byron Unit 1 Cycle Length

2. K. Graesser letter to the Nuclear Regulatory Commission dated October 18,1996, transmitting the Operating Interval Between Eddy Current Inspections for Circumfereratial Indications in the Byron Unit 1

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Steam Generators Via the reference letter 1, the Commonwealth Edison Company (Comed) changed our commitment for the maximum number of days of operation of Byron Unit I for Cycle 8 l

from 448.5 days to 540 days (above T-Hot of 500 F). This timeframe would allow the j

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unit to operate until the steam generators are replaced. The decision to change the commitment was based upon the technicaljustification for operation of the Unit I steam generators for 540 days, which had been transmitted previously via Reference 2, and the expedited availability of the Unit I replacement steam generators. In addition to this quantitative evaluation, Comed believes that the 540 days of operation of Byron Unit 1 is justified given the high quality of the two previous inspections that were performed on Byron I steam generators. Specifically, the 3 coil Plus Point Probe was used during the October 1995 and the April 1996 e

inspections, Eddy Net 95 software was used during the April 1996 inspection, which provided the

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analysts with additional tools to facilitate the detection of circumferential indications, and increase in analyst awareness due to the Fall 1995 pulled tube results at Byron.

l These actions lead to a significant improvement in the detection threshold for top of tube sheet circumferentialindications; therefore, Comed is confident that the condition of the

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Byron Unit i steam generators is not a safety concern at the end of the 540 day cycle 1G0043 9701160190 970107 PDR ADOCK 05000454 P

PDR K:nlaibybwd\\stgen\\bycycle A l'nicom Company

U.S. Nuclear Regulatory Commission January 7,1997 4

As a result of our technicaljustification and to provide additional conservatism, Byron will be submitting to the Staff a request to amend the Technical Specification which would lower the allowable dose equivalent iodine in the reactor coolant from.35 microCuries/ gram to.20 microCuries/ gram for Cycle 8 for Unit 1.

Byron Station is anxious to finalize the steam generator replacement schedule, and therefore, is requesting a prompt decision from the Staff which concurs that our evaluation is a rational and conservative approach to stay within our current licensing basis, and that 540 days of operation above a T-Hot of 500 F is appropriate.

If you have any questions concerning this correspondence, please contact Denise Saccomando, Senior PWR Licensing Administrator at (630) 663-7283.

Sincerely, i

ki 0 hnq John B. Hosmer Engineering Vice President cc:

M. D. Lynch, Senior Project Manager-NRR G. Dick, Byron Project Manger-NRR

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S. Burgess, Senior Resident Inspector-Byron A.B. Beach, Regional Administrator-Rill l

Office of Nuclear Safety-IDNS K:nla'bybwdistgen\\bycycle