ML20207J884

Responds to 861114 Request to Address Issue of Whether Use of Stress Intensification Factor (SIF) of 1.0 for Branch Connections Technically Justified.Approach Similar to That Used at Shoreham Will Provide Technically Sound Resolution

ML20207J884
Person / Time
Site:	Beaver Valley
Issue date:	12/19/1986
From:	Novak T Office of Nuclear Reactor Regulation
To:	Grimes B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
TAC-62939, NUDOCS 8701080635
Download: ML20207J884 (3)

Text

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d. . * ' DEC 191996 Docket No.: 50-412 MEMORANnUM FOR: Brian K. Grimes, Director Division of Quality assurance, Vendor, and Technical Training Center Proorams Office of Inspection and Enforcement FROM: Thomas M. Novak, Acting Director Division of PWR Licensing-A Office of Nuclear Reactor Regulation SURJECT: STRESS INTENSIFICATION FACTOR llSED IN REAVED VALLEY, UNIT NO. P PIPING STRESS ANALYSIS (TAC NO. 6?939)

References:

1. Menorandum from R.K. Grimes to H.L. Thompson dated November 14, 1985.

2 Letter from D.F. t.anders ITeledyne Engineerina Services) to H.D. Denton dated June 30, 1083 with attachment,

" Executive Summary of Final Reoort - Independent Design

( 3.

Review for the Shoreham Nuclear Power Station," TR-5633-3, dated June 30, 1983.

" Final Report-Independent Design Review for the Shorehan Nuclear Power Station," TD-5633-4, dated July ??,1983.

In Reference 1 above, NRR was requested to address whether the use of a stress intensification factor (STF) of 1.0 for branch connections is technically justified. The item was previously identified as a result of an IE inspection of the implementation of an Engineerin Webster Engineering Corporation (SWEC)g Assurance for the Reaver Valley Program perfomed by Stone &

Power Station, linit No. 2. The purpose of this memorandum is to respond to your reouest, and to provide the background information behind our position.

In the past, there were similar controversies over the appropriate STF to be used for evaluating the effects of small piping branch connections on large diameter pipino systems. The reason for the apparent difficulty in selecting an appropriate STF is that in earlier ASME Code editions (i.e., 1971, 1974, and 1977), the figures used for selecting appropriate SIF for various ASME Code Class 2 and 3 piping products did not contain explicit guidance specifically for the run end of small branch connections on larae diameter piping systems.

Althouah use of the stress indices for ASME Class 1 pipino products -- which included those for run ends of branch connections -- was permitted for Class ?

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CONTACT:

D. Terao, ER/DDLA 8701080635 861219 2 49-27037 PDR ADOCK 0500

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' ss l and 3 piping products not shown in the Class 2 and 3 figures, certain restrictions were imposed on the class 1 branch connection physical dimensions which generally were not complied with in class 2 and 3 piping systems (e.g., weld radii control, r r, and branch inside radii, r3 ). Using the Class 1 piping product table and depending on this dimensional control, the minimum SIF for run ends of branch connections would be 1.5.

In the 1980 edition of the ASME Code, the check for run ends of branch connections was added and in the 1080 Winter Addendum, the requirements for controlling their radii were incorporated into the ASME Class P and 3 piping rules. The later Code Addendum also added that when the 2r radius control could not be met, then an additional multiplier of 2.0 should be used and the SIF should not be less than 2.1. Furthermore, the Code added that the control for inside radii was not applicable for branch connections less than 4 inches nominal pipe size.

This specific issue was previously raised in the independent design review (IDR) performed by Teledyne Engineering Services (TEST, for the Shoreham facility for which SWEC was the architect engineer. The design review by TES included a review of the iustification for using a 1.0 SIF for small branch connections. However, the issue was ultimately resolved based on: (11 a .

review of the dimensional requirements for the branch connections at Shoreham, (2) the appropriateness of using later ASME Code paragraphs to supplement the

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(, Shoreham Code of record for piping,+ and (3) a review of over 500 branch connections using a recalculated SIF of 2.1 for the run end connection for which no allowables were exceeded. The results of the Shoreham IDR were transmitted to the NRC staff in References 2 and 3 above. A copy of the TES summary for the SIF issue (ICR No. 5633-27) is attached to this memorandum, and provides a detailed step-by-step account of how the issue was reviewed and resolved by TES.

We concur in the approach used by TES to resolve the SIF issue at Shoreham based on a review of the three factors described above. For Beaver Valley, Unit No. 2, we believe a similar approach--balancing the dimensional require-ments, Code applicability, and actual stress results--can also be used to achieve a reasonable and technically sound resolution. If you have any further questions regarding this issue, please contact D. Terao of my staff at extension 77037.

b Thomas M. Novak, Acting Director Division of PWR Licensing-A Office of Nuclear Reactor Reculation cc: See next page f3 fU)

• The Shoreham Code of Record for piping systems is the ASME B&PV Code .

Section III (19711 up to and including Winter 1972 Addendum.

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