ML20249C400

Requests Review & Approval of Break Evaluation Methodology (leak-before-break) Used to Support Elimination of Augmented Insp Program on RCS Bypass Lines.Repts Containing Reanalysis & Justification of Affected Piping,Encl

ML20249C400
Person / Time
Site:	North Anna
Issue date:	06/23/1998
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20249C401	List: ML20249C400 ML20249C403 ML20249C405
References
98-013, 98-13, NUDOCS 9806290204
Download: ML20249C400 (2)

Text

_ - _-- _ -________ -___-___ ______-__ _ _________-__ __--____-____- -_ _ __ _ _ - _ _ ,

i Vincis:A IsiscTRIC AND I'OWER CmWANY

! Riciiuosin, hGINE A 232(,i i June 23, 1998 1

U.S. Nuclear Regulatory Commission Serial No.98-013 Attention: Document Control Desk NL&OS/ETS R0 Washington, D.C. 20555 Docket Nos. 50-338/50-339 License Nos. NPF-4/NPF-7 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROTECTION AGAINST DYNAMIC EFFECTS ASSOCIATED WITH A LOSS-OF-COOLANT ACCIDENT Currently the UFSAR (3.6.2.3) at North Anna identifies a commitment to perform an augmented inspection of postulated rupture points on certain reactor coolant piping.

The inspection was required in lieu of modifications, which would have consisted of installed pipe whip restraints or barriers to prevent damage to surrounding equipment, if the reactor coolant piping failed. The current augmented inspection program insures against piping failure on the Reactor Coolant System (RCS) and precludes the need for the modifications.

A leak-before-break evaluation was perfromed to support a change in commitment for

' the augmented inspection programs identified in the UFSAR for the reactor coolant loop bypass lines. Therefore, consistent with the guidance provided in the supplementary information provided with the final rule " Modifications of General Design Criteria 4, Requirements for Protection Against Dynamic Effects of Postulated Pipe Ruptures,"

(Federal Register, Vol. 52, No. 207, dated October 27,1986), we request your review and approval of the break evaluation methodology (leak-before-break) used to support the elimination of the augmented inspection program on the RCS bypass lines.

The current augmented inspection program requires that each rupture point be examined 3 times each ten year interval or 12 times the current ASME Section XI Code requirements (25% in 10 years) for Class 1 welds. These examinations have been performed, but with high cost in personnel exposure. It is estimated that in a ten year

! interval the total exposure (Units 1 & 2) resulting from these inspection requirements will exceed 40 person-rem.

kI As a result of the high exposure, a reanalysis was performed of the affected piping.

The reanalysis and supporting justification were completed based on the location of the

! affected piping in the RCS and are included in Attachments 1 and 2 to this letter.

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+1 g\ Y 9806290204 980623 PDR ADOCK 05000338 /

G PDR m e

Attachment 1 provides the exposure evaluation and the technical justification for i eliminating the augmented inspection program for the reactor coolant loop bypass piping. Attachment 2 provides a similar discussion and technical justifications for eliminating the augmented inspection program for the pressurizer spray lines. These reanalyses provide the basis for a proposed commitment change to eliminate the augmented inspection program on the reactor coolant loop bypass lines for both Units 1 and 2 and on the pressurizer spray line for Unit 2. The reanlaysis of the Unit 1 pressurizer spray line indicated that several break point locations could be removed from the augmented inspection program, however, several break point locations were required to remain in the program. Therefore, the commitment for nn augmented inspection of the Unit 1 pressurizer spray line could be reduced, but not eliminated.

Independent of eliminating the augmented inspections, the affected piping will continue to receive inspection as required by the ASME Section XI Code, which includes NDE examination and pressure testing. Continued piping inspections to the ASME Code ensure integrity in these areas. In our opinion, the continued ASME inspections in conjunction with the presented reanalysis justifies the proposed changes. g if you have any questions or require additional information concerning this matter, please contact us.

Very truly yours,

/

James P. O'Hanlon Senior Vice President - Nuclear Attachments Commitments made by this letter:

None cc: U.S. Nuclear Regulatory Commission i l Region 11 Atlanta Federal Center (

61 Forsyth Street, SW l

Suite 23T85 Atlanta, Georgia 30303 i

Mr. M. J. Morgan '

NRC Senior Resident inspector North Anna Power Station l

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