NOC-AE-05001886, Additional Information Regarding Welded Attachments on Piping Systems from Which Arbitrary Intermediate Breaks Were Previously Eliminated

Additional Information Regarding Welded Attachments on Piping Systems from Which Arbitrary Intermediate Breaks Were Previously Eliminated

ML051470162
Person / Time
Site:	South Texas
Issue date:	05/19/2005
From:	Head S South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-05001886, STI: 31882289, TAC MC5191, TAC MC5192
Download: ML051470162 (6)

Text

Nuclear Operating Company South Ek-crk enemtbnSSbiZon PO 2ox229 vrU, Matb 774831AAa otxAsPr*d May 19, 2005 NOC-AE-05001886 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Units I and 2 Docket Nos. STN 50-498, STN 50-499 Additional Information Regarding Welded Attachments on Piping Systems from which Arbitrary Intermediate Breaks were Previously Eliminated (TAC Nos. MC5191 and MC5192)

Reference:

Letter, S. E. Thomas to NRC, "Addition of Welded Attachments to Piping Systems from which Arbitrary Intermediate Breaks were Previously Eliminated,"

dated November 18, 2004 (NOC-AE-04001823)

The referenced letter reported two locations in each unit where welded attachments were added to piping systems from which arbitrary intermediate breaks were previously eliminated. The NRC review of the referenced letter resulted in an informal request for additional information.

The attachment to this letter provides the response to that request.

There are no commitments in this letter.

If there are any questions regarding this submittal, please contact John Conly at (361) 972-7336 or me at (361) 972-7136.

Scott M. Hea Manager, Licensing jtc

Attachment:

Response to Request for Additional Information STI: 31882289

NOC-AE-05001 886 Page 2 of 2 cc:

(paper copy) (electronic copy)

Bruce S. Mallett A. H. Gutterman, Esquire Regional Administrator, Region IV Morgan, Lewis & Bockius LLP U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 David H. Jaffe Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission C. M. Canady Jack A. Fusco City of Austin Michael A. Reed Electric Utility Department Texas Genco, LP 721 Barton Springs Road Austin, TX 78704 Jon C. Wood Cox Smith Matthews Richard A. Ratliff C. Kirksey Bureau of Radiation Control City of Austin Texas Department of State Health Services 1100 West 49th Street J. J. Nesrsta Austin, TX 78756-3189 R. K. Temple E. Alarcon City Public Service Jeffrey Cruz U. S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483

NOC-AE-05001886 Attachment Page I of 4 Response to Request for Additional Information

1. In your request letter (Reference 1), you indicated that the enveloping assessment was performed using Bechtel standard computer program ME-916. The current evaluation for the addition of welded attachment was performed using ME101. Confirm whether MEIOI computer code uses the same methodology as used in ME916 for the design basis enveloping assessment.

Response

The feedwater piping is analyzed using ME101 to determine the primary and secondary stresses and the support loads. The methodology used (ASME Section III, Code Class 2) for design stress limits and support loading combinations is the same for both the original and the modified feedwater piping.

The ME916 program calculates piping stresses at the integral attachments. The methodology used (ASME Code cases N-122, N-391) is the same for both the original attachments and the new attachments. Reference 2 details the methods of analysis used.

STP Nuclear Operating Company (STPNOC) used MEIOI for piping analysis and ME916 to qualify integral welded attachments. As seen in DCN 9704761 on pages 121-133 of 151, STPNOC also used the evaluation procedure added in Code case N-122-2.

2. Subsection NC-3645(a) of ASME Section III, requires that attachments be designed to minimize stress concentrations in applications where the number of stress cycles, due either to pressure or thermal effect, is relatively large for the expected life of the equipment. Confirm whether the stress concentration has been adequately accounted for in your calculation using either ME916 or MEI01 computer code.

Response

The stress concentration has been adequately accounted for in the calculation. STPNOC used the stress indices for the feedwater piping analysis (ME101) for ASME Section III, Code Class 2 piping. The stress indices for the pipe and attachments (ME916) are enveloped stress indices per ASME Code Case N-391 (circular welded attachment for FW-9012-HL5010). The stress indices for the bounding case support (FW-9012-HL5010) are summarized in Table 1.

3. In the request letter, you indicated that the evaluation of the additional welded attachments in the rerouted feedwater piping following the steam generator replacement (SGR) indicated that the existing enveloping assessment performed previously in 1987 (Reference 2) remains bounding for the feedwater piping welded attachments and conform with the stress criteria for the elimination of AlBs discussed in UTFSAR Section

NOC-AE-0500 1886 Attachment Page 2 of 4 3.6.2.1.1. Provide summary evaluation results for the primary stress intensity, the primary plus secondary stress and the cumulative factors for the additional welded attachments on the rerouted feedwater piping due to SGR.

Response

The specific support primary stress intensity, primary plus secondary stress, and the cumulative usage factor for the new added integral welded attachments (IWAs) were not calculated.

However, the new IWAs are qualified by comparison with welded IWAs for supports having a higher range of thermal/OBE loads and stresses. Refer to Table 2 for details.

References

1. STP Nuclear Operating Company letter to NRC, "Addition of Welded Attachments to Piping Systems from Which Arbitrary Intermediate Breaks (AIBS) Were Previously Eliminated," November 18, 2004, NOC-AE-04001823.

2. STP Houston Lighting & Power Company letter to NRC, "Elimination of Arbitrary Intermediate Breaks," ST-HL-AE-2290, dated July 8, 1987.

NOC-AE-05001 886 Attachment Page 3 of 4 Table 1 Summary of Stress Indices for Support 18"FW-9012-HL5010 Stress Pipe per ASME Attachment to the Pipe per ASME Code Case N-391 (ME916)

Indices Section III (ME101) Pipe Attachment Enveloped B1 0.5 C, 1.0 Ki 1.0 B2 1.0 C2 1.0 K2 1.0 C3 1.0 K3 1.0 BT or Bw _ _ _ ___4.618 BL _____ 1.1 Bc or BN _ _ _ __ _2.528 Cw 6.6396 9.236 9.236 CL 2.1062 2.2 2.2 Cc or CN __4.2809 5.056 5.056 BT __Not required for this support CT __Not required for this support KT, K1 3.6 3.6 T 3.6

______________ ~ _ ~_ _ _ ~ _ __~ _ _ _ _ _ _ l__ (Partial penetration as weld)

NOC-AE-05001886 Attachment Page 4 of 4 Table 2 Stress Summary for Added Attachments Primary Stress Intensity Primary plus Secondary Stress and Usage factors Design Condition Emergency Condition Faulted Condition Normal and Upset Condition Support No. (NB-3652) (NB -3655.2) (NB-3656) (NB-3653) Cumulative EQ. 9 Allowable EQ. 9 Allowable EQ. 9 Allowable EQ. 10 EQ. 12 EQ. 13 Allowable Usage psi Psi psi psi psi psi Sn Max Se Max Max 3Sm Factor (CUF) 1.5Sm psipsi psi FW-9012- 7706 25950 - - 34910 51900 49635 51900 0.7835 HL5010 FW- 1012- 7200 25950 - - 28500 51900 27497 51900 < 0.635(2.4)

HL5001 (loop A)

FW-1012- 8200 25950 - - 29100 51900 66783(5) 884075 60477' 51900 < 0.635 4 HL5006 (loop A)

FW-1018- 7500 25950 - - 14800 51900 Note (1) - 51900 < 0.635 4)

HL5014 (loop D) _ _ _ _ _ _ _I I II_ _

FW-1014- 15300 25950 - 19100 51900 Note (1) 51900 < 0.635('4 HLSOIS (loop B) I I I I FL-2018- Unit 2 is qualified by comparison with Unit I analysis.

HL5014 (loop D)

HL-2014- Unit 2 is qualified by comparison with Unit I analysis.

HL5015 (loop B)

Notes:

(1) The evaluation was to assess the fatigue effects on new and existing integral welded attachments (IWAs) for all four loops of main feedwater lines. The fatigue effects on piping systems are evaluated with EQ. 10 and EQ. 11 of ASME Section III, Paragraph NB3600 based on thermal range and OBE range loads. Based on a review of all the supports with IWAs and comparisons of thermal/OBE loads and stresses between:

a. the existing analysis (before steam generator replacement, i.e., pre-SGR)

b. the new analysis (post-SGR)

c. the loads for feedwater support F'-V-9012-1IL5010 selected previously for fatigue evaluation.

The two supports on Loop A, HL5001 and HL5006, were subsequently selected for detailed fatigue evaluations as bounding cases to qualify new IWAs added to the supports listed in table above. Thus the stresses and cumulative usage factors for the new IWAs are determined to be lower when compared to bounding case supports analyzed (HL5001 and HL5006).

(2) Alternating stresses Sa,, =23828 psi for support HL5001 (3) Alternating stress S.,, =24899 psi for support 1L5006 (4) CUP = 0.635 calculated for alternating stress Sl,, = 30809 psi (5) Equations 12, 13 and thermal stress ratchet check of NB-3653.7 were satisfied.