ML20069C024

Interim Deficiency Rept SD 370/82-12 Re Butt Welds That May Not Meet ASME Code Criteria for Being Flush.Analyses Being Performed to Determine Stress Indices Associated W/Worst Case Flush Weld Profile.Final Rept to Be Submitted 820222

ML20069C024
Person / Time
Site:	Mcguire
Issue date:	01/21/1982
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, SD-370-81-12, NUDOCS 8203080208
Download: ML20069C024 (3)

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.a WILLI AM Q. PAFIM ER, J M, s , c ,'[ E.'o'$ c',",' January 21, 1982 m'~o"<;^g^ 73 i s-

' 4 Mr. James P. O'Reilly, Regional Administrator p U. S. Nuclear Regulatory Commission '

Region II  %

RECElyEO C 101 Marietta Street, Suite 3100 h MAR 05 N2h ~

Atlanta, Georgia 30303 -

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V Re: McGuire Nuclear Station p Unit 2 g Docket No. 50-370 g /

Dear Mr. O'Reilly:

Pursuant to 10 CFR 50.55e, please find attached Significant Deficiency Report j SD 370/81-12 (interim) concerning butt welds that may not meet ASME Code criteria for being " flush." A final report will be submitted by February 22, 1982. This is also being reported for Unit 1 via LER 369/81-192.

V (y truly yours, u.L. w /4 4 ( ,

William O. Parker, J .

! PBN/php i Attachment l cc: (w/ attachment) l Director Mr. P. R. Bemis Office of Inspection and Enforcement NRC Resident Inspector U. S. Nuclear Regulatory Commission McGuire Nuclear Station l

Washington, D. C. 20555 i

l Mr. Ralph Birkel Division of Project Management

_ Office of Nuclear Reactor Regulation-U. S. Nuclear Regulatory Commission Washington, D. C. 20555 OFFIC1nUdNY

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DUKE POWER COMPANY McCUIRE NUCLEAR STATION SIGNIFICANT DEFICIENCY i

' REPORT NO._: SD.370/81-12-(interim)

REPORT DATE: January 21, 1982 i

-FACILITY: McGuire Nuclear Station, Unit 2 1

IDENTIFICATION OF DEFICIENCY:

-Welds identified as " flush" may not meet the stringent requirements of the i .ASME Code criteria as defined.in Table NB-3683.2-1, footnote (2)(a). Spec-

, Ifically, the requirement that the finished contour of the weld shall not 4 '

exceed a 7 slope had not been satisfied at the weld I.D.

INITIAL REPORT:

, The initial report was made to Mr. A. Ignatonis of Region II, USNRC, on December 22, 1981 by Mr. W. O. Henry and Mr. J. N. Underwood, both of Duke Power Company, 422 S. Church Street, Charlotte, NC 28242.

DESCRIPTION OF DEFICIENCY:

The initial deficiency was first identified by a Catawba Nuclear Station NCI which reported that certain butt welds did not meet the ASME Code criteria

'for being-flush as defined in Table NB-3683.2-1. This NCI specifically-

! pointed out that the l'.D. of the weld did not meet the 70 contour as stipulated in footnote (2)(a) of that table. Furthermore, a review deter-mined that the Catawba Construction procedure for flush welds may not '

provide adequate assurance that the weld contour on the I.D. is s 7 .0 A review of.the corresponding McGuire Nuclear' Station' procedure indicates that similar conditions could exist for McGuire flush welds.

> .The impact associated with the failure-to satisfy the ASME Code is in the stress analysis (Class 1 only for McGuire 2) used to demonstrate code compliance for these welds. Because lower stress indices are associated with flush welds,-the adequacy'of.the' current revision of the piping stress 2 -analysis calculations is in question. There are approximately 136 welds identified'as flush on McGuire Unit 2.

i ANALYSIS OF SAFETY IMPLICATIONS:

'The' stress analysis calculations generally ' employ the prr cedures outlined'

[ in NB3600 to ensure piping' system integrity forfall loading conditions. . If-the welds in question are found not to satisfy the ASME Code requirements

. associated with flesh welds, certain' stress indices would be incorrect and

_of a lower value than'those associated.with the worst case as-welded condition.-

The effect'of;these higher stress indices would be.seen:only in the local-fatigue calculations and not affect the overall structural; response or gross

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structural strength.. However,lthere may befa reduction in the ASME safety .

factor against fatigue fa~ilure for all cyclic-type loadings.. . ,

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REPORT NO. SD-370/81-12 (interim)

Page 2 t

i CORRECTIVE ACTION:

Although some uncertainty presently exists as to whether the welds in

question meet the stringent flush weld requirements on the weld I.D.,

they are known to more closely resemble the ASME flush weld than the 4 "as-welded" butt weld-profiles permitted by the Code. Duke Power Company is performing an' analysis to determine the stress indices associated with

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the " worst case" flush weld profile. This will be done by employing more

~ stringent analytical procedures outlined in the Code. Once the new indices i- are. defined, they will be compared with the existing Code indices to

' determine impact on existing calculations.

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!. Preliminary results of the analysis of some conservative models indicates that the indices for the Duke flush welds are very similar to the indices for ASME flush welds. The analysis is scheduled to.be completed in the near future, with a final report to be. submitted by February 22, 1982.

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