ML24348A188
| ML24348A188 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/12/2024 |
| From: | Ameren Missouri, Framatome, Union Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML24347A225 | List: |
| References | |
| ULNRC-06910 | |
| Download: ML24348A188 (1) | |
Text
Enclosure 2 to U LN RC-06910 Callaway Tube to Tubesheet Welding Report, Revision 1
framatGme Callaway Tube to Tubesheet AN Revision I Welding Report Technical Report December 2024 (c) 2024 Framatome Inc.
0414-12-F04 (Rev. 005, 04/10/2024)
Copyright © 2024 Framatome Inc.
All Rights Reserved ANP-4076 Revision 1 0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP-4076 Revision I Callaway Tube to Tubesheet Welding Report Technical Report Prn i Nature of Changes Section(s)
Item or Page(s) 1 1.0 2
3.0 3
4.0 Description and Justification Added statement of requirements for plant-specific AMP.
Added statement of compressive stress from [2].
Added statement of compressive stress as justification.
0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP4076 Revision I Callaway Tube to Tubesheet Welding Report Technical Report Page ii Contents Page
1.0 INTRODUCTION AND BACKGROUND
SUMMARY
OF LR-ISG 2016-01 1-1 2.0 METHOD 2-1
3.0 ASSESSMENT
RESULTS 3-1
4.0 CONCLUSION
4-1
5.0 REFERENCES
5-1 0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP-4076 Revision 1 Callaway Tube to Tubesheet Welding Report Technical Report Page iii Nomenclature Acronym Definition AMP Aging Management Program Cr Chromium MCR Manufacturing Completion Report PWSCC Primary Water Stress Corrosion Cracking RSG Replacement Steam Generator wt%
Weight Percent 0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP-4076 Revision 1 Callaway Tube to Tubesheet Welding Report Technical Report Pacie 1-1
1.0 INTRODUCTION AND BACKGROUND
SUMMARY
OF LR-ISG-2016-O1 NRC License Renewal Interim Staff Guidance 2016-01 [1] suggests a plant-specific aging management program (AMP) be in place if replacement steam generators (RSG5) are susceptible to primary water stress corrosion cracking (PWSCC). For the tube-to-tubesheet weld reg ion, three factors are considered : susceptible material, conducive environment, and sufficiently high tensile stress.
For units with thermally treated Alloy 690 steam generator tubes and with tubesheet cladding using Alloy 600 weld material, a plant-specific AMP is necessary UNLESS the applicant (Callaway, in this case) confirms that the industrys analyses for tube-to-tubesheet weld cracking (e.g., chromium content for the tube-to-tubesheet weld is approximately 22 percent and the tubesheet cladding is in compression) are applicable and bounding for its unit.
Nickel alloys are potentially susceptible to PWSCC based on chromium content. No PWSCC has been observed in nickel alloys with chromium contents greater than 22 weight percent (wt%) chromium in nuclear power plant applications, which includes Alloy 690 type materials (approximately 27 to 31 percent chromium).
For tubesheets clad with alloy 600 type material, both Alloy 82 (1 8 to 22 wt% chromium) and Alloy 182 (13 to 17 wt% chromium) cladding is typically present. The majority of the tubesheet is clad with Alloy 82. Regions clad with Alloy 182 would normally include the central region of the tubesheet, a strip adjacent to the divider plate (potentially involving the first row of tubes), and local repairs.
As a result, for tube-to-tubesheet welds made between Alloy 690 tubes and Alloy 600 type cladding material, the weld is a mixture of the tube and clad materials. The welds chromium content depends on that of the two precursor constituents. For these welds, a more detailed assessment is needed since the chromium content could potentially be low enough to make the welds more susceptible to PWSCC.
0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP-4076 Revision I Callaway Tube to Tubesheet Welding Report Technical Report Page 2-1 2.0 METHOD A records search of Callaway-1 RSGs 294-297 manufacturing completion reports (MCRs) supports determination of tube-to-tubesheet weld chromium content in greater detail than previously presented [2]. From EPRI Technical Report 3002002850, Section 2.6.2 [3], the chromium content of the weld can be determined by
%Crweld = %Crtube(O.52) + %CTclad(O.48)
(1)
For all tubes in RSGs 294-297 (SGI-5G4, respectively), the minimum chromium value is taken for the Alloy 690 tube material. For all tubesheet cladding material in RSGs 294-297, the minimum chromium content is taken for the Alloy 182 weld material. These minimum values are averaged via equation (1) to determine the minimum expected Cr wt% for tube-to-tubesheet welds in the four RSGs.
0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP-4076 Revision I Callaway Tube to Tubesheet Welding Report Technical Report Page 3-1
3.0 ASSESSMENT
RESULTS For minimum chromium values of the tube and cladding the given mixing equation confirms a weld content of greater than 22 wt% chromium for Callaway-1 RSGs 294-297 (SGI-SG4, respectively). This bounding value exceeds the required minimum value of 22 wt% chromium for PWSCC susceptibility as identified in EPRI Technical Report 3002002850 [3].
Additionally, the surface stress on the primary side of the tubesheet is determined to be compressive [2].
0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP-4076 Revision I Callaway Tube to Tubesheet Welding Report Technical Report Page 4-1
4.0 CONCLUSION
A plant-specific AMP for Callaway-1 RSGs 294-297 is not needed as stipulated by LR ISG-2016-O1 because the minimum calculated chromium content based on Callaway-1 RSGs 294-297 tube-to-tubesheet welds is sufficient (>22 wt%) and surface stress on the primary side of the tubesheet is compressive.
0414-12-F04 (Rev. 005, 04/10/2024)
Framatome Inc.
ANP-4076 Revision I Callaway Tube to Tubesheet Welding Report Technical Report Page 5-1
5.0 REFERENCES
- 1. NRC License Renewal Interim Staff Guidance LR-ISG-2016-01. Changes to Aging Management Guidance for Various Steam Generator Components.
- 3. EPRI 2014 Technical Report 3002002850. Steam Generator Management Program:
Investigation of Crack Initiation and Propagation in the Steam Generator Channel Head Assembly.
0414-1 2-F04 (Rev. 005, 04/10/2024)
For Informatbn Only 0414-12-FOl (Rev. 002, 01/15/2018)
[ramatGme LICENSING DOCUMENT APPROVAL 1
Licensing Document Approval for:
103-4076-001 Callaway Tube to Tubesheet Welding Report Document Number/Title Document Preparer:
Sections: All CI NEIL John Neil 12/5/2024 Print Name Signature Date Preparers Technical Manager:
Sections: All CA WICKER Craig Wicker 12/5/2024 Print Name Signature Date Reviewer:
Sections: All SL YODER Stacy Yoder 12/5/2024 Print Name Signature Date Project Manager:
BJ WATSON 12/5/2024 Beverly Watson Print Name Signature Date Regulatory Affairs:
MEBYRAM 12/5/2024 Morris Byram Print Name Signature Date Page 1 of I