ML20154L862

Forwards Response to NRC 980820 RAI Re GL 97-05, SG Tube Insp Techniques

ML20154L862
Person / Time
Site:	Farley
Issue date:	10/12/1998
From:	Dennis Morey SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-97-05, GL-97-5, NUDOCS 9810200100
Download: ML20154L862 (3)

Text

.. .~. - - - . . . . - - - _ - . . - . - . .. - . - . .

. . . .Oave Morey SIuthernNucle r Vice President - Operating Compa::y

' Farley Project P.O. Box 1295 Birmingham. Alabama 35201

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Tel 205.992.5131 October 12, 1998 SOUTHERN gg Energy to ServeYourWorld" Docket Nos.: 50-348 10 CFR 50.54f 50-364 U. S. Nuclear Regulatory Commission -

ATTN: Document Control Desk l Washington, DC 20555 Joseph M. Farley Nuclear Plant Response To Request for Additional Information Regarding Generic Letter 97-05, Steam Generator Tube Insoection Techniaues

Ladies and Gentleme, Southern Nuclear Opc.ating Company (SNC) received a request dated August 20,1998, for -

additional information (RAI) regarding our response to Generic Letter (GL) 97-05. The SNC l response to the RAI is attached.

3 Respectfully submitted, NM i:

Dave Morey Sworn to andsubscribed b Tore me this/2 Yay of 1998

' WAQJtle

'k Notary Pub'lic V d S67J My Commission Expires: N#L.e > - A-o / d d/

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, EWC/mafrai9705. doc Attachment cc: Mr. L. A. Reyes, Region II Administrator g'\

Mr. J.1. Zimmerman, NRR Project Manager Mr. T. P. Johnson, Plant Sr. Resident Inspector QC I

9810200100 981012 ""

PDR ADOCK 05000348 P pag.

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ATTACIIMENT l

l SNC RESPONSES TO A REQUEST FOR ADDITIONAL INFORMATION, DATED AUGUST 20,1998, REGARDING GENERIC LETTER 97-05 l

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SNC Response to NRC Request For AdditionalInformation Related to Generic Letter 97-05, ,

• "Stenin Generator Tube Inspection Techniques," Joseph M. Farley Nuclear Plant, Units I and 2 l

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l. Question- i l

Discuss the qualification that enables the differentiation between MBMs and other  !

volumetric forms of tube degradation (e.g.,intergranular attack), or provide ,

evidence from pulled tubes or industry experience that supports your practice of  !

characterizing MBMs through eddy current inspection techniques.  !

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Response

The oractice described below is the current policy for disposition of MBMs:

The Farley practice with respect to disposition of MBM signals does not rely on a I specific ability to discriminate among the forms of volumetric wall loss. The identification of a signal as a possible flaw by bobbin screening is based upon phase anaiysis, using ASME standards to establish the range of phase angle shift attributable to possible flaw content. MBMs identified from bobbin data normally have flaw phase l angles that correlate to less than 10 %.

Bobbin signals identified as possible MBMs are examined with a rotating probe. If a volumetric indication (VOL) is observed, the indication is subjected to historic bobbin  ;

data review. If the normalized amplitude and phase angle of the bobbin lissajous trace are not significantly changed from the " baseline" values, the MBM designation is confirmed and the tube need not be repaired. If significant increase in bobbin amplitude or depth derived from phase angle relative to the baseline bobbin result is observed, then .

the possibility exists that active degradation has occurred at this location, and the tube is repaired or removed from service. The verification that there has been no change in the indication from baseline serves as a basis to ensure MDMs can be differentiated from other forms of volumetric degradation.

MBMs examined with rotating coils do not usually present discrete flaw characteristics.

The presence of erack-like characteristics, confirmed by rotating coil examination,  ;

together with significant amplitude or depth increase by the historical bobbm review, is 4 cause for repair of the tube. )

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2. Question:

State in your response whether it is the practice at Farley to review preservice or the most recent inspectiou data to determine ifindications were evident in the past.

Response

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For bobbin examination, the reference or " baseline" condition to which the signal is )

compaxd is taken from the earliest useful inspection archive. These data are from the 1985 (Unit 1) and 19.86 (Unit 2) inspections.

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