ML20210N529

Notifies That Util 860804 Request for Deviation from ASME Code Section Iii,Subsection Nf, Component Supports of 1974 Edition Through 1975 Addenda Acceptable.Relief Applicable Only to Welds in Pipe Supports

ML20210N529
Person / Time
Site:	Vogtle
Issue date:	09/29/1986
From:	Youngblood B Office of Nuclear Reactor Regulation
To:	Conway R GEORGIA POWER CO.
References
NUDOCS 8610060536
Download: ML20210N529 (4)

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2 9 SEP 1986 Docket Nos.: 50-424 and 50-425 Mr. Richard Conway, Vice President and Project General Manager Georgia Power Company Box 299A, Route 2 Waynesboro, Georgia 30830

Subject:

Code Addenda of Record for Pipe Support Allowable Stresses -

Vogtle Electric Generating Plant, Units 1 and 2 By letter dated August 4,1986, Georgia Power Company (GPC) requested a deviation from the ASME Code of Record by excluding the stress limitation for allowable weld stresses in subparagraphs NF-3226.5, NF-3321.1(c),

NF-3392.1, and Mandatory Appendix XVII, Figure XVII - 2211(c) of the 1974 Edition through the Sumer 1975 Addenda. In the referenced letter GPC requested pennission to use the allowable weld stresses in Table NF-3292.1-1 of the Code for piping supports.

The Code of Record for pipe support construction for Vogtle, Units 1 and 2 is ASME Section III, Subsection NF, " Component Supports," 1974 Edition through the Sumer 1975 Addenda. In subparagraphs NF-3226.5, NF-3321.1(c),

NF-3392.1 and Mandatory Appendix XVII, Figure XVII - 2211(c)-1 of the Code of Record, the allowable tensile stress at the contact surface of a weld which transmits a stress in the through thickness direction of plates and elements of rolled shapes is limited to the lesser of .30 times the tensile yield stress or .25 times the minimum tensile strength of the steel. The original objective of these very conservative allowable stresses was to minimize the potential for a failure in the support due to lamellar tearing.

Lamellar tearing is a cracking phenomenon which can occur in the parent metal while it is cooling af ter the welding process. I~c is usually of con-cern only within large welded structures involving a high degree of stiffness and restraint. Industry experience indicated that the additional weld metal required by these conservative allowable stresses resulted in large weld sizes that did not relieve the problem of tearing of the base material. The additional weld metal can produce significant strains in the parent metal re-sulting in the joining up of base metal inclusions. Since the potential for lamellar tearing still existed, the ASME Subcomittee on Nuclear Power (SCIII) recognized the need for action to:

1. Delete the lower allowable stress limits

2. Provide guidance on welded joint design GOO 60536860929 A ADOCK 05000424 Pna.

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y Mr. Richard Conway The action to revise the allowable stresses was taken first since these low values were creating a problem. Therefore, the Winter 1978 Addenda to ASME Section III deleted these conservative allowable stresses from applicable portions of subparagraphs NF-3226.5, NF-3321.1(c), NF-3392.1, XVII-2211(c) and Figure XVII-2211(c)-1. The allowable stresses for these types of welds are nowdontained in Table NF-3929.1-1.

Action on the joint design wns delayed because of the difficulty in developing requirements which would be universally applicable. As a result, it was not until the 1983 Edition of ASME Section III that subsection NF, Subparagraph NF-4430, "Special Requirements for Welding," was added to be applicable to large welded members of component supports, exclusive of piping supports. These new requirements are intended to be a more positive method of preventing lamellar tearing than the previous method of reducing allowable weld stresses. Piping supports were excluded from these requirements since their configuration and size are such that lamellar tearing is not a problem.

In the referenced letter, GPC requested pennission to use the allowable weld stresses in Table NF-3292.1-1 for piping supports rather than the lower allow-ables in the Code of Record for Vogtle, Units 1 and 2. Based on the above ,

discussion, we have concluded that this request can be granted with no adverse ./

impact on the public health and safety.

This relief from the Code of Record is only applicable to welds in pipe supports. e A separate request should be made if GPC intends to use the allowable stresses in NF-3292.1-1 for welds in any supports, other than for piping, which consists of plates or rolled shapes and transmits loads in the through thickness direc-tion of the weld. If such a request is submitted, it should contain either a commitment to ASME Section III,1983 Edition, Subsection NF-4430 or a detailed description of the welding joint design employed to minimize lamellar tearing in Vogtle, Units 1 and 2.

Accordingly, based upon the above review, the staff finds your proposal to be acceptable.

Sincerely, d

B. J. You d, Director PWR Project Directorate #4 Division of PWR Licensing-A cc: See next page

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Mr. R. E. Conway Georgia Power Company Vogtle Electric Generating Plant cc:

Mr. L. T. Gucwa Resident Inspector Chief Nuclear Engineer Nuclear Regulatory Comission Georgia Power Company P. O. Box 572 P.O . Box 4545 Waynesboro, Georgia 30830 Atlanta, Georgia 30302 Mr. Ruble A. Thomas DeppLsh Kirkland, III, Counsel Vice President - Licensing Office of the Consumers' Utility Vogtle Project Council Georgia Power Company / Suite 225 Southern Company Services, Inc. 32 Peachtree Street, N.W.

P.O. Box 2625 Atlanta, Georgia 30303 Binningham, Alabama 35202 James E. Joiner Mr. Donald 0. Foster Troutman, Sanders, Lockerman, Vice President & Project General Manager & Ashmore Georgia Power Company Candler Building Post Office Box 299A, Route 2 127 Peachtree Street, N.E.

Waynesboro, Georgia 30830 Atlanta, Georgia 30303 Danny Feig Mr. J. A. Bailey 1130 Alta Avenue Project Licensing Manager Atlanta, Georgia 30307 Southern Company Services, Inc.

P.O. Box 2625 Birmingham, Alabama 35202 Ernest L. Blake, Jr.

Bruce W. Churchill, Esq.

Shaw, Pittman, Potts and Trowbridge 1800 M Street, N.W.

Washington, D. C. 20036 Mr. G. Bockhold, Jr.

Vogtle Plant Manager Georgia Power Compar.y Route 2, Box 299-A Waynesboro, Georgia 30830 Regional Administrator, Region II U.S. Nuclear Regulatory Comission 101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323

Mr. Richard Conway -2_ SEP 7966 The action to revise the allowable stresses was taken first since these low values were creating a problem. Therefore, the Winter 1978 Addenda to ASME Section III deleted these conservative allowable stresses from applicable portions of subparagraphs NF-3226.5, NF-3321.1(c), NF-3392.1, XVII-2211(c) and Figure XVII-2211(c)-1. The allowable stresses for these types of welds are now contained in Table NF-3929.1-1.

Action on the joint design was delayed because of the difficulty in developing requirements which would be universally applicable. As a result, it was not until the 1983 Edition of ASME Section III that subsection NF, Subparagraph NF-4430, "Special Requirements for Welding," was added to be applicable to large welded members of component supports, exclusive of pioing supports. These new requirements are intended to be a more positive method of preventing lamellar tearing than the previous method of reducing allowable weld stresses. Piping supports were excluded from these requirements since their configuration and size are such that lamellar tearing is not a problem.

In the referenced letter, GPC requested permission to use the allowable weld stresses in Table NF-3292.1-1 for piping supports rather than the lower allow-ables in the Code of Record for Vogtle, Units 1 and 2. Based on the above discussion, we have concluded that this request can be granted with no adverse impact on the public health and safety.

This relief from the Code of Record is only applicable to welds in pipe supports.

A separate request should be made if GPC intends to use the allowable stresses in NF-3292.1-1 for welds in any supports, other than for piping, which consists of plates or rolled shapes and transmits loads in the through thickness direc-tion of the weld. If such a request is submitted, it should contain either a commitment to ASME Section III,1983 Edition, Subsection NF-4430 or a detailed description of the welding joint design employed to minimize lamellar tearing in Vogtle, Units 1 and 2.

Accordingly, based upon the above review, the staff finds your proposal to be acceptable.

Sincerely, B. J. Youngblood, Director PWR Project Directorate #4 Division of PWR Licensing-A cc: See next page i JPartlow MMiller 1RC JUK BGrimes P0'Connor Local PDR EJordan 0GC-Bethesda PRC System NThomposon ACRS (10)

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