ML20058L181

Forwards Safety Evaluation of Large Break LOCA Event Reanalysis Per 10CFR50.46 Re Peak Clad Temp Increases

ML20058L181
Person / Time
Site:	Mcguire, McGuire
Issue date:	08/01/1990
From:	Tucker H DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9008070040
Download: ML20058L181 (3)

Text

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(TO4,L1734LT1 DUKEPOWER August 1, 1990 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Subject:

McGuire Nuclear Station, Docket Nos. 50-369 and 50-370 Notification of Peak Clad Temperature Change Pursuant to 10 CFR 50.46 Licensees are required to notify the NRC of channes in the peak clad temperature analysis. Attached is the safety evaluation of the McGuire large break LOCA event re-analysis in compliance with 10 CFR 50.46.

If there are any questions concerning this subject, pleases contact Steve LeRoy at (704) 373-6233.

Very truly yours,

, #g hW Hal B. Tucker SEL561 Attachment Mr. S. D. Ebneter, Region II Administrator U.S. Nuclear Regulatory Commission 101 Marietta Street, NW. Suite 2900 Atlanta, Georgia 30323 Mr. D.S. Ilood, Project Manager Office of Nuclear Reactor Regulation, DoNRC Washington, D.C. 20555 Mr. P.K. Van Doorn NRC Senior Resident Inspector McGuire Nuclear Station t

p hf OCK 05000369 FDC 99l m _ _ - - _____

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..7 U.S. Nucl cr Regulttory Commicalen  !

ATTN: Document Control Desk- l August 1, 1990 Attachment Duke Power Company McGuire Nuclear Station Analysis of Large Break LOCA Peak C' Lad Temperature Increase The McCd re Units 1 and 2 large break LOCA event documented in McGuire FSAR Section 15.6.4 1.as recently been reanalyzed. The peak clad temperature for .

the limiting :.ase, e riouble ended cold Icg guillotine break with minimum safeguards and a discharge coefficient of 0.6, increased to 2138.6 -

degrees 4. The new analysis changed four specific things:

3 1.- The level of steam generator tube plugging was increased to ten percent:

2. The assumed delay between reaching the low pressurizer pressure ['

safety injection setpoint and crediting full safety injection flow was increased to 42 seconds:

3. The assumed safety injection flow was decreased to the values given on page 2 of this attachment; and,

4. The cold leg accumulator assumed pressure was decreased to 564  !

psig.  ;

All of these changes were made to enhance oporating flexibility at the station by taking advantage of margin-in the existing analysis. The specific areas of potential enhancement are to follow fort

1. increased steam generator tube plugging, or its equivalent in tube sleeving

2. Increased diesel generator starting times

3. Increased ESF valve stroke timest 4.. Relaxed safety injection piping branch line flow balance criteria; '

5. Reduced safety injection flow requirements; and,

6. Increased margin between the safety analysis assumption and the Technical Specification LCO on cold leg accumulator minimum

. pressure.  ;

Since most of the requirements are contained within the station Technical Specifications, specific submittals would be made at a later date to realize these enhancements. Please note that the analysis results of 2138.6 degrees-F continues to comply with the ECCS Acceptance Critorion of 10 CFR '

50.46(b)(1). Therefore, no proposed schadule is necessary per 10 CFR 50.46(a)(3)(11) for providing a re-analysis, or for taking other action to demonstrate compliance.

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