ML18153B399

Requests Use of Code Case N-524 at North Anna Unit 1 & 2 Second Interval ISI Program,Surry Unit 1 Second & Third ISI Programs & Unit 2 Second Interval ISI Program

ML18153B399
Person / Time
Site:	Surry, North Anna
Issue date:	12/10/1993
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
93-754, NUDOCS 9312200131
Download: ML18153B399 (3)

Text

t,.:,-l e e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 December 10,-1993 United States Nuclear Regulatory Commission Attention:

Document Control Desk Washington, D. C. 20555 , Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNITS 1 AND 2 INSERVICE INSPECTION PROGRAMS CODE CASE N-524 USAGE APPROVAL Serial No.93-754 NL&P/ETS Docket Nos. 50-280 50-281 50-338 50-339 License Nos. DPR-32 DPR-37 NPF-4 NPF-7 The ASME Code Committee approved Code Case N-524, Alternative Examination Requirements for Longitudinal Welds in Class 1 and 2 Piping Section XI, Division 1, August 9, 1993 (attached).

We have just recently received our copy of the formal Code Case from ASME. Due to its recent approval, Code Case N-524 has not yet been approved for use in Regulatory Guide 1.147, lnservice Inspection Code Case Acceptability ASME Section XI, Division 1. However, provisions stated in footnote 6 to 1 O CFR 50.55a provide for use of other Code Cases upon request, if approved by the Director of the Office of Nuclear Reactor Regulation pursuant to 1 O CFR 50.55a(a)(3).

Accordingly, we are requesting use of Code Case N-524 at North Anna for the Unit 1 and 2 Second Interval lnservice Inspection Programs, and at Surry for the Unit 1 Second and Third Interval lnservice Inspection Programs, and for the Unit 2 Second Interval lnservice Inspection Program. The basis for our request is provided below. The ASME Section XI Code (1989 Edition) currently requires one pipe diameter in length, but no more than 12 inches, be examined for Class 1 longitudinal piping welds. Class 2 longitudinal piping welds are required to be examined for a length of 2.5t, where t is the thickness of the weld. These lengths of weld are measured from the intersection of the circumferential weld and longitudinal weld. Code Case N-524 significantly reduces the required examination volume or surface area. It does this by limiting the eiamination of the longitudinal weld to the volume or area contained within the examination requirements of the intersecting circumferential weld. -This would include the weld and 1 /2 inch on both sides of the weld crown for surface examinations, and 1 /4 inch on both sides of the weld crown for volumetric examinations (lower one _third). / .. *:: .-:-__ '":-.. -. -.. I

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.. ~*--" Code Case N-524 directs the examination effort at the high risk area associated with the weld intersections.

It eliminates low risk areas on the longitudinal weld from examination, significantly reducing examination time requirements and exposure to examination personnel.

Compliance with the existing ASME Section XI requirements, in lieu of the Code Case, results in unnecessary personnel exposure to complete the required examinations without a compensating increase in the level of quality or safety. The use of Code Case N-524 has been reviewed by the North Anna and Surry Station Nuclear Safety and Operating Committees.

If there are any questions concerning this matter, please contact us. Very truly yours, qt~~ r~W.L. Stewart Attachment cc: U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W. Atlanta, Georgia 30323 Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Mr. R. D. McWhorter NRG Senior Resident Inspector North Anna Power Station CASES OF ASME BOILER AND PRESSURE VESSEL CODE Approval Date: August 9, 1993 See Numerical Index for expiration and any reaffirmation dates. Case N-524 Alternative Examination Requirements for Longitudinal Welds in Class 1 and 2 Piping Section XI, Division 1 Inquiry: What alternative requirements may be plied to the surface and volumetric examination of longitudinal piping welds specified in Table IWB-2500-1, Examination Category B-J, Table IWC-2500-1, Examination Categories C-F-1 and C-F-2 ination Category C-F prior to Winter 1983 da), and Table IWC-2520, Examination Category G (1974 Edition, Summer 1975 Addenda)?

Reply: It is the opinion of the Committee that the following shall apply: (a) When only a surface examination is required, examination of longitudinal piping welds is not quired beyond those portions of the welds within the examination boundaries of intersecting ential welds. (b) When both surface and volumetric tions are required, examination of longitudinal piping welds is not required beyond those portions of the welds within the examination boundaries of secting circumferential welds provided the following requirements are met. (1) Where longitudinal welds are specified and locations are known, examination requirements shall be met for both transverse and parallel flaws at the intersection of the welds and for that length of gitudinal weld within the circumferential weld amination volume; (2) Where longitudinal welds are specified but locations are unknown, or the existence of dinal welds is uncertain, the examination ments shall be met for both transverse and parallel flaws within the entire examination volume of secting circumferential welds. 903 CASE N-524 SUPP. 6 -NC