ML23244A175

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September 7, 2023, NRC Public Meeting with Steam Generator Task Force - NRC Presentation
ML23244A175
Person / Time
Issue date: 09/07/2023
From: Leslie Terry
NRC/NRR/DNRL/NCSG
To:
References
Download: ML23244A175 (1)
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Text

Divider Plate and Tube-to-Tubesheet Weld Cracking Guidance and Proposed Changes to Steam Generators Program Leslie Terry, NRR/DNRL/NCSG NRC Meeting with Industry Steam Generator Task Force September 7, 2023

Purpose

Background - Divider Plate and Tube-to-tubesheet Weld Cracking Guidance

  • LR Guidance

- LR-ISG-2016-01 for managing cracking due to primary

- Volumes 1 and 2 of Generators programs NUREG-2191, Revision 0

- Steel (with nickel-alloy cladding);

- NUREG-2192, Revision 0, nickel alloy divider plates Further Evaluation (FE) 3.1.2.2.11 - Nickel alloy tube-to-tubesheet welds

  • FE for plant-specific
  • Plant-specific program beyond program to evaluate (in addition to) existing effectiveness of programs (Water Chemistry existing programs and Steam Generators)

(Water Chemistry and Steam Generators) 3 3

Feedback - Divider Plate Cracking Guidance Material Weld Material Industry analysis Plant-specific (EPRI 3002002850) program required applicable and beyond existing bounding programs1 690 690 N/A No 600 600 Yes No 600 600 No Yes 1 If a plant-specific program is not necessary, then aging is managed by the existing Water Chemistry and Steam Generators programs 4

Feedback - Tube-to-tubesheet Weld Cracking Guidance Tube Tubesheet Alternate Repair Industry analysis Plant-specific Material Cladding Criteria (C*, F*, W*, (EPRI 3002002850) program Material or H*) approved for applicable and required both hot- and cold- bounding beyond leg side of SG existing programs1 690 690 N/A N/A No 690 600 N/A Yes No 690 600 N/A No Yes 600 N/A Yes N/A No 600 N/A No N/A Yes 1 If a plant-specific program is not necessary, then aging is managed by the existing Water Chemistry and Steam Generators programs 5

Proposed Changes to SLR AMP XI.M19, Steam Generators

  • Drafts for comment published in Federal Register (FR) on July 11, 2023 (88 FR 44160)

Basis Doc.)

  • Public Comment Period: July 11, 2023 - September 11, 2023
  • Comments should be submitted in writing by any of the following methods:
  • Mailing comments to Office of Administration, Mail Stop: TWFN-7-A60M, U.S.

Nuclear Regulatory Commission, Washington, DC 20555-0001, ATTN: Program Management, Announcements and Editing Staff 6

Proposed Changes to SLR AMP XI.M19, Steam Generators Contd

  • Clarify type of corrosion that SG tube plugs may experience
  • Clarify that extensive deposit buildup on the secondary side of SGs could affect tube integrity
  • Update inspection frequency of divider plate assemblies, tube-to-tubesheet welds, heads (channel or lower/upper heads), and tubesheets to be consistent with the maximum inspection interval allowed by the SG tube inspection requirements for the given SG tube material in Revision 5 of the standard technical specifications that were published in September 2021
  • Add guidance on providing a comparison of plant-specific parameters and industry analyses (EPRI 3002002850) to determine if a plant is bounded by the industry analyses for SG divider plate assembly and tube-to-tubesheet weld cracking 7

Proposed Changes to SLR AMP XI.M19, Steam Generators Contd

  • Change from using a plant-specific AMP to the One-Time Inspection program for evaluating the effectiveness of the Water Chemistry and Steam Generators programs at mitigating PWSCC of divider plate assemblies and tube-to-tubesheet welds
  • Clarify that the Water Chemistry and Steam Generators programs are used to manage PWSCC of divider plate assemblies and tube-to-tubesheet welds, even if it is determined that use of the One-Time Inspection program is not needed to confirm their effectiveness at mitigating PWSCC
  • Update and add references 8

Summary

  • Currently, a plant-specific program to evaluate effectiveness of Water Chemistry and Steam Generators programs at mitigating PWSCC is necessary when:
  • Divider plate assemblies are Alloy 600 or contain Alloy 600 type weld materials, and industry analyses (EPRI 3002002850) are not applicable and bounding
  • Tube-to-tubesheet welds
  • Alloy 690 SG tubes and Alloy 600 tubesheet cladding, and industry analyses (EPRI 3002002850) are not applicable and bounding
  • Alloy 600 SG tubes, and alternative repair criteria within tubesheet approved for only the hot leg or cold-leg side of SG
  • Public comment period for draft GALL-SLR, SLR-SRP, and Tech. Basis Doc.

closes on September 11, 2023 9

References

Investigation of Crack Initiation and Propagation in the Steam Generator Channel Head Assembly

10

References Contd

  • Corrected Tables 3.1-1 and Table 3.2-1, published August 2023 (ML23213A036)
  • NUREG-1432, Revision 5, Standard Technical Specifications Combustion Engineering Plants, dated September 2021 (ML21258A421 (Volume 1) and ML21258A424 (Volume 2))

11

Questions 12

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