ML20065L450

Submits Predicted MSLB Total Leakage for Bounding SG C,Per Requirement of Amend 106 to License NPF-3 Re SG Tube Interim Plugging Criteria

ML20065L450
Person / Time
Site:	Farley
Issue date:	04/15/1994
From:	Dennis Morey SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RTR-NUREG-1477 NUDOCS 9404210079
Download: ML20065L450 (2)

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• Southern Nuclear Operating company Post OMice Box 1295

, Strmingham, Abbama 35201 Tefephone (205) 868 5131 L k o..e umy Southern Nudear Operating Company Vice PrWdent radey Project the southem electnc Systern April 15,1994 Docket No.: 50-348 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Joseph M. Farley Nuclear Plant - Unit 1 InterintPlugging Criteria Anal y

. sis Report Gentlemen:

By letter dated April 5,1994, the NRC issued Amendment No.106 for Unit 1 of the Joseph M. Farley Nuclear Plant concerning steam generator tube interim plugging criteria.

The Safety Evaluation for the amendment required that the following be submitted prior to restart:

1. The predicted MSLB leakage will be reported to the NRC prior to restart from the refueling outage.

Response

Predicted Main Steam Line Break Total Leakage for the Bounding Steam Generator (Steam Generator C)

Probability of Leakage ' NUREG-1477 Leak Rate Distribution Calculation Correlation Log Logistic 0.82 gpm 0.023 gpm Log Normal 0.58 gpm 0.021 gpm Log Cauchy 3.0 gpm 0.047 gpm Logistic 2.2 gpm 0.038 gpm Normal 1.8 gpm 0.034 gpm Cauchy 4.4 gp m 0.061 gpm -

These predicted leakage values are based on a 60% probability of detection; the exclusion of several " outlier" data points from the leakage database; the cycle 11 voltage growth rates; and are at a 98% confidence level for the NUREG-1477 calculation and 95% confidence level for the regression calculation. The exclusion of the outlier data points results in a more conservative prediction (higher-predicted leakage) for the NUREG-1477 calculations. The voltage growth rates for cycle 12 were negligible and bounded by the cycle 11 growth rates. Therefore, the use of the Cycle I i growth rates results in a conservative (higher) estimate of leakage.

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!*. Page3 The largest predicted leakage,4.4 gpm for the Cauchy distribution, is significantly less than the 22.8 gpm Farley limit.

2. The NRC will be informed, prior to plant restart from the refueling outage, of any unexpected inspection findings relative to the assumed characteristics of the flaws at the tube support plate elevations. This inc.. ;s any detectable circumferential indications or detectable indicatioris extending outside the tube support plate.

Response: No unexpected inspection fmdings relative to the assumed characteristics ofilaws at the tube support plate were found.

The detailed assessment of the interim plugging criteria methodology will be forwarded afler the completion of the outage.

If there are any questions, please advise.

Respectfully submitted, SOUTIIERN NUCLEAR OPERATING COMPANY h })!ra Dave Morey y REM / cit:IPCUiC13. Doc cc: Mr. S. D. Ebneter Mr. T. A. Reed Mr. B, L Siegel Mr T. M. Ross

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