NL-08-0280, Application of a Dissimilar Metal Weld Full-Structural Weld Overlay

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Application of a Dissimilar Metal Weld Full-Structural Weld Overlay
ML080570570
Person / Time
Site: Hatch Southern Nuclear icon.png
Issue date: 02/26/2008
From: David Jones
Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-08-0280
Download: ML080570570 (33)
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Text

David H. Jones Southern Nuclear Vice President Operating Company, Inc.

Engineering 40 Inverness Center Parkway Birmingham, Alabama 35242 Tel 205.992.5984 Fax 205.992.0341 SOUTHERNA February 26, 2008 COMPANY Energy to Serve YOur World'"

Docket No.: 50-321 NL-08-0280 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 1 Application of a Dissimilar Metal Weld Full-Structural Weld Overlay Ladies and Gentlemen:

On February 22, 2008 ultrasonic examination indicated that a flaw existed on control rod drive (CRD) return line nozzle dissimilar metal weld 1C11-1CRD-3-R 18A that exceeded ASME Code criteria. This line was cut and capped in 1977 per the requirements of NUREG-0619. Recent technological developments for examination (Le., phased array examination technique) have facilitated the complete characterization of pre-existing but previously incompletely characterized conditions. On February 23, 2008 the flaw was confirmed and fully characterized using phased array techniques after the weld was conditioned.

Based on a review of previous inspection data, coupled with the results of the phased array examination, SNC believes that this flaw has existed for several years. The proposed corrective action is the application of a full-structural weld overlay.

Pursuant to 10 CFR 50.55a(a)(3)(i), Southern Nuclear Operating Company (SNC) hereby requests NRC approval of proposed alternative ISI-GEN-ALT-08-01, Version 1.0 to allow the application of a full-structural weld overlay over weld 1C11-1 CRD-3-R-18A.

This proposed alternative is similar to alternative ISI-GEN-ALT-07-01, Revision 2.0, submitted on December 26, 2007 for the Farley Nuclear Plant and the Vogtle Electric Generating Plant. Alternative ISI-GEN-ALT-07-01 was based primarily on NRC approved ISI-GEN-ALT-06-03, Revision 2.0 for the Farley Nuclear Plant.

The differences between ISI-GEN-ALT-08-01 and ISI-GEN-ALT-07-01 are as follows:

1. This alternative applies to a single weld,
2. The end cap base material for Hatch is a nickel-based alloy versus the stainless steel safe-end configuration described in the Vogtle and Farley submittals, and

U. S. Nuclear Regulatory Commission NL-08-0280 Page 2

3. For BWR applications, crediting of the base layer toward weld thickness if there is at least 20% Cr, versus 24% for PWRs.

This alternative is for the Hatch Nuclear Plant (HNP) 4 th lSI Interval. The details of the 10 CFR 50.55a request for alternative are contained in Enclosure 1. The list of regulatory commitments is contained in Enclosure 2.

Approval is requested by February 29, 2008 to support application of the weld overlay prior to transitioning to Mode 3, currently scheduled for March 10, 2008.

If you have any questions, please advise.

David H. Jo Vice President, Engineering DHJ/MNW/daj

Enclosures:

1. Request for Alternative - ISI-GEN-ALT-08-01, Version 1.0 Application of a Dissimilar Metal Weld Full-Structural Weld Overlay
2. List of Regulatory Commitments cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, Vice President - Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Acting Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. J. A. Hickey, Senior Resident Inspector - Hatch

Edwin I. Hatch Nuclear Plant Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(i)

Application of a Dissimilar Metal Weld Full-Structural Weld Overlay Enclosure 1 ISI-GEN-ALT-08-01, Version 1.0

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 This proposed alternative is technically similar to ISI-GEN-ALT-07-01, Version 2.0 previously developed for Farley Nuclear Plant and Vogtle Electric Generating Plant, except that it is specific for one weld. ISI-GEN-ALT-07-01, Version 2.0 is in the final stages of NRC approval.

Plant Site-Unit: Hatch Nuclear Plant - Unit 1 (HNP-1).

Fourth ISI Interval extending from January 1, 2006 through December 31, Interval Dates:

2015.

Requested Date for Approval : Approval is requested by February 29, 2008 to support plant startup.

ASME Code Components Category B-F, Alloy 82/182 dissimilar metal (DM) butt weld.

Affected:

Applicable Code The applicable Code edition and addenda is ASME Section XI, Rules for Inservice Edition and Inspection of Nuclear Power Plant Components, 2001 Edition with Addenda Addenda:

through 2003. The exception is that for ASME Section XI, Appendix VIII, the 2001 Edition of Section XI will be used. This exception is based on 10 CFR 50.55a(b)(2)(xxiv) which states, The use of Appendix VIII and the supplements to Appendix VIII and Article I-3000 of Section XI of the ASME BPV Code, 2002 Addenda through the latest edition and addenda incorporated by reference in paragraph (b)(2) of this section, is prohibited.

NOTE Unless identified otherwise, all Code references provided herein are to ASME Section XI.

Applicable Code IWA-4110 of ASME Section XI requires that repairs of welds shall be performed in Requirements: accordance with Article IWA-4000. IWA-4300 requires that defects be removed or reduced to an acceptable size.

Reason for HNP-1 DM weld 1C11-1CRD-3-R-18A has an indication that is approximately 2.3 Request: long at the inside surface and has a maximum depth of 60% through-wall. This indication is attributed to stress corrosion cracking (SCC).

This DM weld joins the N9 reactor pressure vessel Control Rod Drive (CRD) Return nozzle (P No. 3) to a nickel-base alloy cap (P No. 43). The weld material is Alloy 82/182 (F No. 43). The details of this configuration are shown in Appendix 6, Figure 1. (Dimensions in Figure 1 are for ISI use and not for design).

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 This cap was installed in 1977 after the CRD return line was re-routed to Feedwater per the requirements of NUREG-0619. The DM weld was subsequently stress improved using a mechanical stress improvement process (MSIP) in 1993.

The DM weld was ultrasonically (UT) examined eight times from 1977 through 1994 using progressively improved UT techniques. Five of these examinations were prior to 1993. In 1993 this weld was examined by UT prior to and after the MSIP treatment with an indication being detected. A reexamination in 1994 identified the same indication at the inside surface of the weld in the area of the current flaw, but the indication was characterized as geometry because there was no observable depth. In late 2007, due to SCC occurrences at other sites, the BWRVIP provided requirements to its members requiring each utility to evaluate welds that could have examination issues due to the surface conditions. As a result of the industry requirements, SNC performed surface conditioning on weld 1C11-1CRD-3-R-18A during the current outage (1R23) to improve the examination of the weld. After surface conditioning, the indication length and through-wall dimensions were observed. Final sizing of the indication was performed using a qualified phased-array technique.

Southern Nuclear Operating Company (SNC) proposes to overlay this weld as the method of repair; however,Section XI of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (Section XI Code) does not provide rules for the design of weld overlays or for repairs without removal of flaws.

Additionally, Code Cases N-504-2 and N-638-1, which have been approved by the NRC for use, do not provide the methodology for overlaying nickel alloy butt welds.

Therefore, this proposed alternative is requested.

A comparison to Code Cases N-504-2 and to N-638-1 was provided in ISI-GEN-ALT-07-0; therefore, it is provided in this alternative. (See Appendix 4 and Appendix 5).

Proposed Proposed Alternative Alternative and Basis for Use:

In lieu of using the IWA-4000 Repair Procedures in the Section XI Code, SNC proposes to use the following alternative requirements for the design, fabrication, pressure testing, and examination of a full-structural weld overlay (FSWOL). This FSWOL will provide an acceptable methodology for reducing a defect in the DM weld to an acceptable size by increasing the wall thickness through deposition of an SCC resistant weld overlay. The methodology is:

1. General Requirements:

(a) An FSWOL will be applied by deposition of weld reinforcement (weld overlay) over the low alloy steel nozzle (P- 3), the DM weld (F-43), and the cap (P-43) as shown in Appendix 6, Figure 2. The weld reinforcement will consist of Alloy 52/152. (Note: As used in this alternative, the use of Alloy 52/152 refers to the family of filler metals which includes filler metals such as 52, 52M, and 52MS.)

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 (b) The Alloy 52/152 weld overlay filler metal is an austenitic nickel alloy having a chromium (Cr) content of at least 28%. The weld overlay is applied 360 degrees around the circumference of the item, e.g., safe end to nozzle weld, and will be deposited using a Welding Procedure Specification (WPS) for groove welding, qualified in accordance with the Construction Code and Owners requirements and identified in the Repair/Replacement Plan. As an alternative to the post-weld heat treatment requirements of the Construction Code and Owners requirements, the provisions for ambient temperature temperbead welding will be used on the ferritic nozzle. (See Ambient Temperature Temperbead Welding, which is located in Appendix 1 to this proposed alternative). The maximum area of an individual weld overlay on the finished surface of the ferritic material shall be no greater than 300 square inches.

(c) Prior to deposition of the FSWOL, the surface will be examined by the liquid penetrant method. Indications larger than 1/16-inch shall be removed, reduced in size, or corrected in accordance with the following requirements.

1. One or more layers of weld metal shall be applied to seal unacceptable indications in the area to be repaired, with or without excavation. The thickness of these layers shall not be used in meeting weld reinforcement design thickness requirements. Peening the unacceptable indication prior to welding is permitted.
2. If correction of indications identified in (c)1 is required, the area where the weld overlay is to be deposited, including any local repairs or initial weld overlay layer, shall be examined by the liquid penetrant method. The area shall contain no indications greater than 1/16-inch prior to the application of the structural layers of the weld overlay.

(d) Weld overlay deposits shall meet the following requirements:

The austenitic nickel alloy weld overlay shall consist of at least two weld layers deposited using a filler material such as that identified in 1(b). The first layer of weld metal deposited may not be credited toward the required thickness. Alternatively, for BWR applications, a diluted layer may be credited toward the required thickness, provided the portion of the layer over the austenitic base material, austenitic filler material weld, and the associated dilution zone from an adjacent ferritic base material contain at least 20% Cr, and the Cr content of the deposited weld metal is determined by chemical analysis of the production weld or of a representative coupon taken from a mockup prepared in accordance with the WPS for the production weld.

(e) Welding will only be performed for applications predicted not to have exceeded a thermal neutron fluence of 1 x 1017 (E< 0.5 eV) neutrons per cm2 prior to welding.

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1

2. Crack Growth Considerations and Design (a) Crack Growth Considerations - Crack growth calculations will be performed.

Flaw characterization and evaluation requirements shall be based on the as-found flaw. The size of all flaws will be projected to the end of the design life of the overlay. Crack growth, including both stress corrosion and fatigue crack growth, shall be evaluated in the materials in accordance with IWB-3640. If the flaw is at or near the boundary of two different materials, evaluation of flaw growth in both materials is required. This report will be submitted within 90 days after plant startup.

(b) Design of the FSWOL The following design analysis shall be completed in accordance with IWA-4311.

1. The axial length and end slope of the weld overlay shall cover the weld and the heat affected zones on each side of the weld, and shall provide for load redistribution from the item into the weld overlay and back into the item without violating applicable stress limits of ASME Section III, NB-3200. Any laminar flaws in the weld overlay shall be evaluated in the analysis to ensure that load redistribution complies with these requirements. These requirements will usually be satisfied if the weld overlay full thickness length extends axially beyond the projected flaw by at least 0.75 Rt , where R is the outer radius of the item and t is the nominal wall thickness of the item.
2. Unless specifically analyzed in accordance with 2(b)1 above, the end transition slope of the overlay shall not exceed 45 degrees. A slope of not more than 1:3 is recommended.
3. The thickness of the FSWOL shall be determined based on the assumption of a through-wall flaw, with a length of 360 degrees in the underlying pipe. The overlay will be applied, so that the criteria of IWB-3640 are met after the overlay is applied. The determination of the thickness shall include the deposit analysis requirements of 1(d).
4. The effects of any changes in applied loads, as a result of weld shrinkage from the entire overlay, on other items in the piping system (e.g., support loads and clearances, nozzle loads, changes in system flexibility and weight due to the weld overlay) shall be evaluated. (There are no pre-existing flaws previously accepted by analytical evaluation to be considered in this evaluation.) Included are:
i. A stress analysis will be performed that demonstrates that the pressure-retaining components will perform their intended design E1-4

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 function with the FSWOL installed. The stress analysis report will include results showing that the requirements of Subarticles NB-3200 and NB-3600 of the ASME Code,Section III are satisfied. The stress analysis will also include results showing that the requirements of IWB-3000 of the ASME Code,Section XI, are satisfied. The results will show that the postulated crack including its growth would not adversely affect the integrity of the overlaid welds. This report will be submitted within 90 days after plant startup.

ii. (Leak-before-break does not apply.)

3. Examination and Inspection In lieu of all other examination requirements, the examination requirements proposed herein shall be met. Nondestructive examination methods shall be in accordance with IWA-2200, except as specified herein. Nondestructive examination personnel shall be qualified in accordance with IWA-2300. Ultrasonic examination procedures and personnel shall be qualified in accordance with Appendix VIII,Section XI, as implemented through the performance demonstration initiative (PDI). (The PDI Program Status for Code Compliance and Applicability developed in June 2005 indicates that the PDI Program is in compliance with Appendix VIII, 2001 Edition of Section XI as amended and mandated by 10 CFR 50.55a, Final Rule dated October 1, 2004.) Ultrasonic examination will be performed to the maximum extent achievable.

Post-Overlay Examinations There are two examinations to be performed after the overlay is installed, i.e., the Acceptance Examination of the Overlay and the Preservice Examination. The purpose of the Acceptance Examination is to assure a quality overlay was installed. The purpose of the Preservice Examination is to provide a baseline for future examinations and to locate and size any cracks that might have propagated into the upper 25% of the original wall thickness and evaluate accordingly. While listed below as two separate examinations the two examinations may be performed during the same time period. SNC will provide the NRC, within 14 days after the completion of the ultrasonic examination of the weld overlay installations, (1) the examination results of the weld overlays and (2) a discussion of any repairs to the overlay material and/or base metal and the reason for repair.

The NDE requirements listed below cover the area that will be affected by application of the overlay. Any SCC degradation would be in the DM weld or the adjacent heat affected zone (HAZ). Further, the original weld and adjacent base materials have received a radiographic examination (RT) prior to the initial acceptance of the existing butt weld. The proposed surface and volumetric examinations provide adequate assurance that any defects produced by welding of the overlay or by extension of pre-existing defects will be identified.

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 (a) Acceptance Examination of the Overlay

1. The weld overlay shall have a roughness average (RA) of 225 micro-inches (250 RMS) or better and a flatness sufficient to allow for adequate examination in accordance with procedures qualified per Appendix VIII.

The weld overlay shall be examined to verify acceptable configuration.

2. The weld overlay and the adjacent base material for at least 1/2 inch from each side of the weld overlay shall be examined using the liquid penetrant method. The weld overlay shall satisfy the surface examination acceptance criteria for welds of the Construction Code or ASME Section III, NB-5300. The adjacent base metal shall satisfy the surface examination acceptance criteria for base material of the Construction Code or ASME Section III, NB-2500. When ambient temperature temperbead welding is used, the liquid penetrant examination shall be conducted at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the third layer of the weld overlay has been completed.

See Appendix 7 for 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold time justification.

3. The examination volume A-B-C-D in Figure 1, which is provided in Appendix 2 to this proposed alternative, shall be ultrasonically examined to assure adequate fusion (i.e., adequate bond) with the base metal and to detect welding flaws, such as interbead lack of fusion, inclusions, or cracks. The interface C-D shown between the overlay and the weld includes the bond and the heat affected zone from the overlay. When ambient temperature temperbead welding is used, the ultrasonic examination shall be conducted at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the third layer of the weld overlay has been completed. See Appendix 7 for 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold time justification.
4. Planar flaws shall meet the preservice examination standards of Table IWB-3514-2. In applying the acceptance standards, wall thickness tw shall be the thickness of the weld overlay. For weld overlay examination volumes with unacceptable indications, the unacceptable indications will be removed and the volume will be re-welded. Re-examination per IWB-2420 is not required because unacceptable indications will be removed and the volume will be re-welded.
5. Laminar flaws shall meet the acceptance standards of Table IWB-3514-3 with the additional limitation that the total laminar flaw shall not exceed 10% of the weld surface area and that no linear dimension of the laminar flaw area exceeds 3.0 inches. Additional requirements are:
i. The reduction in coverage of the examination volume in Figure 1 (which is provided in Appendix 2 to this proposed alternative) due to laminar flaws shall be less than 10%. The dimensions of the E1-6

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 uninspectable volume are dependent on the coverage achieved with the angle beam examination of the overlay.

ii. Any uninspectable volume in the weld overlay beneath a laminar flaw shall be assumed to contain the largest radial planar flaw that could exist within that volume. This assumed flaw shall meet the preservice examination standards of Table IWB-3514-2. In applying the acceptance standards, wall thickness tw shall be the thickness of the weld overlay. Both axial and circumferential planar flaws shall be assumed.

iii. If the preservice acceptance criteria of Table IWB-3514-2 are not met, the assumed flaw shall be evaluated and shall meet the requirements of IWB-3640. The IWB-3640 evaluation shall be submitted to the NRC within 90 calendar days of the completion of the refueling outage. If the assumed flaw is not acceptable for continued service per IWB-3640, the lamination shall be removed or reduced in area such that the assumed flaw is acceptable per IWB-3640.

6. A general requirement after welding is to examine supports to verify design tolerances are still met. There are no supports to be examined.

(b) Preservice Inspection

1. The examination volume A-B-C-D in Figure 2, which is provided in Appendix 3 to this proposed alternative, shall be ultrasonically examined.

The angle beam shall be directed perpendicular and parallel to the piping axis, with scanning performed in four directions, to locate and size any cracks that might have propagated into the upper 25% of the original wall thickness or into the weld overlay.

2. The preservice examination acceptance standards of Table IWB-3514-2 shall be applied to planar indications in the weld overlay material. If the indication is found acceptable per Table IWB-3514-2 the weld overlay will be placed in service and the inservice schedule and acceptance criteria of 3(c) will be followed. In applying the acceptance standards, wall thickness, tw, shall be the thickness of the weld overlay. Planar flaws not meeting the preservice acceptance standards of Table IWB-3514-2 shall be repaired.

Re-examination per IWB-2420 is not required because unacceptable indications will be removed and the volume will be re-welded.

3. Cracks in the outer 25% of the original wall thickness shall meet the design analysis requirements as addressed in Section 2, Crack Growth Considerations and Design, of this proposed alternative.

(c) Inservice Inspection E1-7

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 Inservice examinations of the FSWOLs will be performed in accordance with Q-4300 and 4310 of Appendix Q to the 2004 Edition of Section XI with Addenda through 2005 with modifications. Appendix 8 shows Q-4300 and 4310 with the SNC modifications shown in italics.

4. Pressure Testing A system leakage test shall be performed in accordance with IWA-5000.
5. Documentation Use of this proposed alternative shall be documented on ASME Form NIS-2 or NIS-2A.

Basis for Use:

The use of weld overlay materials resistant to SCC (e.g., Alloy 52/152) that create low tensile or compressive residual stress profiles in the original weld provide increased assurance of structural integrity. The weld overlay is of sufficient thickness and length to meet the applicable stress limits from ASME Section III, NB-3200. Crack growth evaluations for SCC and fatigue of any as-found flaws or any conservatively postulated flaws will ensure that structural integrity will be maintained.

Weld overlay repairs of dissimilar metal welds have been installed and performed successfully for many years in BWRs and recently in PWRs. Weld overlay performance has been excellent. This alternative provides improved structural integrity and reduced likelihood of leakage for the primary system. Accordingly, the use of the alternative provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(a)(3)(i).

Duration of Proposed The proposed alternative is applicable to the 4th ISI Interval.

Alternative:

Precedents: This proposed alternative meets the technical requirements set forth in ISI-GEN-ALT-07-03, Revision 2.0 for Vogtle Electric Generating Plant and Farley Nuclear Plant.

References:

None Status: Awaiting NRC approval.

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 1 AMBIENT TEMPERATURE TEMPERBEAD WELDING 1.0 GENERAL REQUIREMENTS (a) This appendix applies to dissimilar austenitic filler metal welds between P-Nos. 1, 3, 12A, 12B, and 12C1 materials and their associated welds and welds joining P-No. 8 or 43 materials to P-No. 1, 3, 12A, 12B, and 12C materials with the following limitation:

This Appendix shall not be used to repair SA-302 Grade B material unless the material has been modified to include from 0.4% to 1.0% nickel, quenching and tempering, and application of a fine grain practice. (P-No. 12C designation refers to specific material classifications originally identified in ASME Section III and subsequently reclassified in a later Edition of ASME Section IX).

(b) The maximum area of an individual weld overlay based on the finished surface over the ferritic base material shall be 300 square inches.

(c) Repair/replacement activities on a dissimilar-metal weld in accordance with this Appendix are limited to those along the fusion line of a nonferritic weld to ferritic base material on which 1/8- inch, or less of nonferritic weld deposit exists above the original fusion line.

(d) If a defect penetrates into the ferritic base material, repair of the base material, using a nonferritic weld filler material, may be performed in accordance with this Appendix, provided the depth of repair in the base material does not exceed 3/8-inch.

(e) Prior to welding the area to be welded and a band around the area of at least 1-1/2 times the component thickness or 5 inches, whichever is less, shall be at least 50 degrees Fahrenheit.

(f) Welding materials shall meet the Owner's Requirements and the Construction Code and Cases specified in the Repair/Replacement Plan. Welding materials shall be controlled so that they are identified as acceptable until consumed.

(g) Peening may be used, except on the initial and final layers.

2.0 WELDING QUALIFICATIONS The welding procedures and the welding operators shall be qualified in accordance with ASME Section IX and the requirements of 2.1 and 2.2 provided below.

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 1 (Continued)

AMBIENT TEMPERATURE TEMPERBEAD WELDING 2.1 Procedure Qualification (a) The base materials for the welding procedure qualification shall be of the same P-Number and Group Number, as the materials to be welded. The materials shall be postweld heat treated to at least the time and temperature that was applied to the materials being welded.

(b) The root width and included angle of the cavity in the test assembly shall be no greater than the minimum specified for the repair.

(c) The maximum interpass temperature for the first three layers of the test assembly shall be 150 degrees Fahrenheit.

(d) The test assembly cavity depth shall be at least 1 inch. The test assembly thickness shall be at least twice the test assembly cavity depth. The test assembly shall be large enough to permit removal of the required test specimens.

The test assembly dimensions surrounding the cavity shall be at least the test assembly thickness and at least 6 inches. The qualification test plate shall be prepared in accordance with Figure 1-1.

(e) Ferritic base material for the procedure qualification test shall meet the impact test requirements of the Construction Code and Owner's Requirements. If such requirements are not in the Construction Code and Owner's Requirements, the impact properties shall be determined by Charpy V-notch impact tests of the procedure qualification base material at or below the lowest service temperature of the item to be repaired. The location and orientation of the test specimens shall be similar to those required in (f) below, but shall be in the base metal.

(f) Charpy V-notch tests of the ferritic heat-affected zone (HAZ) shall be performed at the same temperature as the base metal test of (e) above. Number, location, and orientation of test specimens shall be as follows:

(i) The specimens shall be removed from a location as near as practical to a depth of one-half the thickness of the deposited weld metal. The coupons for HAZ impact specimens shall be taken transverse to the axis of the weld and etched to define the HAZ. The notch of the Charpy V-notch specimen shall be cut approximately normal to the material surface in such a manner as to include as much HAZ as possible in the resulting fracture. When the material thickness permits, the axis of a specimen shall be inclined to allow the root of the notch to be aligned parallel to the fusion line.

(ii) If the test material is in the form of a plate or a forging, the axis of the weld shall be oriented parallel to the principal direction of rolling or forging.

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 1 (Continued)

AMBIENT TEMPERATURE TEMPERBEAD WELDING (iii) The Charpy V-notch test shall be performed in accordance with ASME Section II, Part A, SA-370. Specimens shall be in accordance with SA-370, Figure 11, Type A. The test shall consist of a set of three full-size 10 mm X 10 mm specimens. The lateral expansion, percent shear, absorbed energy, test temperature, orientation and location of all test specimens shall be reported in the Procedure Qualification Record.

(g) The average lateral expansion value of the three HAZ Charpy V-notch specimens shall be equal to or greater than the average lateral expansion value of the three unaffected base metal specimens. However, if the average lateral expansion value of the HAZ Charpy V-notch specimens is less than the average value for the unaffected base metal specimens and the procedure qualification meets all other requirements of this appendix, either of the following shall be performed:

(1) The welding procedure shall be requalified.

(2) An Adjustment Temperature for the procedure qualification shall be determined in accordance with the applicable provisions of NB-4335.2 of Section III, 2001 Edition with 2002 Addenda. The RTNDT or lowest service temperature of the materials for which the welding procedure will be used shall be increased by a temperature equivalent to that of the Adjustment Temperature.

2.2 Performance Qualification Welding operators shall be qualified in accordance with ASME Section IX.

3.0 WELDING PROCEDURE REQUIREMENTS The welding procedure shall include the following requirements.

(a) The weld metal shall be deposited by the automatic or machine GTAW process.

(b) Dissimilar metal welds shall be made using A-No. 8 weld metal (ASME Section IX, QW-442) for P-No. 8 to P-No. 1, 3, or 12 (A, B, or C) weld joints or F-No. 43 weld metal (ASME Section IX QW-432) for P-No. 8 or 43 to P-No. 1, 3, or 12 (A, B, or C) weld joints.

E1-11

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 1 (Continued)

AMBIENT TEMPERATURE TEMPERBEAD WELDING (c) The area to be welded shall be buttered with a deposit of at least three layers to achieve at least 1/8-inch overlay thickness, with the heat input for each layer controlled to within +/-10% of that used in the procedure qualification test. The heat input of the first three layers shall not exceed 45,000 J/inch under any conditions.

Particular care shall be taken in the placement of the weld layers of the austenitic overlay filler material at the toe of the overlay to ensure that the HAZ and ferritic base metal are tempered. Subsequent layers shall be deposited with a heat input not exceeding that used for layers beyond the third layer in the procedure qualification.

(d) The maximum interpass temperature for field applications shall be 3500F for all weld layers regardless of the interpass temperature used during qualification. The interpass temperature limitation of QW-406.3 need not be applied.

(e) The interpass temperature shall be determined by (e)(1). If it is not possible to use (e)(1) then (e)(2) and (e)(3) may be used in combination.

(1) Temperature measurement (e.g., pyrometers, temperature indicating crayons, thermocouples) during welding. Trending of the interpass temperatures during installation of overlays using contact pyrometers has shown that the difference between the observed temperatures and the maximum allowable interpass temperature of 3500F is large and considerable margin exists. Based on this trending, there is reasonable assurance that the temperature of any bead will not approach the maximum allowable temperature. SNC will monitor the interpass temperature every weld pass for the first three layers. For additional layers, the frequency of measuring interpass temperature may be reduced when the temperature is at least 1000 F below the 3500 F limit and trend data supports a reduced monitoring frequency.

(2) Heat flow calculations using the variables listed below as a minimum.

(i) welding heat input (ii) initial base material temperature (iii) configuration, thickness, and mass of the item being welded (iv) thermal conductivity and diffusivity of the materials being welded (v) arc time per weld pass and delay time between each pass (vi) arc time to complete the weld (3) Measurement of the maximum interpass temperature on a test coupon that is equal to or less than the thickness of the item to be welded. The maximum heat input of the welding procedure shall be used in the welding of the test coupon.

(f) Particular care shall be given to ensure that the weld region is free of all potential sources of hydrogen. The surfaces to be welded, filler metal, and shielding gas shall be suitably controlled.

E1-12

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 1 (Continued)

AMBIENT TEMPERATURE TEMPERBEAD WELDING Figure 1-1: QUALIFICATION TEST PLATE E1-13

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 2 ACCEPTANCE EXAMINATION VOLUME Examination Volume A-B-C-D FIGURE 1: ACCEPTANCE EXAMINATION VOLUME E1-14

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 3 PRESERVICE EXAMINATION VOLUME 1/2 in. (min.) 1/2 in. (min.)

(Note 1)

A B t/4 D C t

Examination Volume A-B-C-D FIGURE 2: PRESERVICE EXAMINATION VOLUME E1-15

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 4 COMPARISON OF PROPOSED ALTERNATIVE WITH N-504-2 CODE CASE N-504-2 PROPOSED ALTERNATIVE N-504-2 for weld overlay repair of SS piping Proposed alternative is for dissimilar metal weld overlay repairs.

Reply-reduce a flaw to acceptable size by weld Reply- reduce a flaw to acceptable size by weld overlay on austenitic SS piping overlay on austenitic stainless steel or austenitic nickel alloy piping, components and associated welds Material covered is P-8 Per Section 1.0(a) of Appendix 1 materials covered are P-8 or P-43 and P-1, 12A, 2B or 12c or between P-1, 3, 12A, 12B or 12C. Also includes P-8 to P-43, P-8 to P-8 or P-43 to P-43 joined with austenitic filler materials (b) Filler Material - low C (0.035% max) SS (b) Filler Materials - Low C (0.035% max) SS or austenitic nickel alloy (28% Cr min.)

(c) (d) Repair of indications prior to overlay (c) Repair of indications prior to overlay (Same as N-504-2)

(e) Weld Reinforcement (d) Weld Reinforcement Min. 2 layers with-7.5 FN. In first austenitic (1) Min. 2 layers with-7.5 FN. In first layer SS layer 5 FN acceptable by evaluation. 5FN acceptable if deposited weld metal less than 0.02% C.

(2) Provides requirements for austenitic nickel alloy weld overlay.

(f) (g) Design - Requires flaw evaluation of the 2.0 Design existing flaw based on IWB-3640 for design life. Requires flaw evaluation of the existing flaw Requires postulated 100 % through wall for based on IWB-3640. Flaw evaluation of both design of the weld overlay (full-structural) except materials required if flaw is at or near the for four or fewer axial flaws. Meet ASME boundary. Requires postulated 100 % through Section III for primary local and bending wall for design (full-structural) of the weld overlay.

stresses and secondary peak stresses. Axial length and end slope shall cover the weld Requires end transition slope less than 45 and heat affected zones and shall provide for degrees. Axial length requirement usually met if load redistribution into the item and back into the overlay 0.75 (Rt) 1/2 beyond flaws. Shrinkage overlay either out violating stress limits. There is and other applied loads evaluated on other no exception for four or fewer axial flaws. Design items and other flawed welds in system. analysis per IWA-4311. Meet ASME Section III, NB-3200 applicable stress limits. Any laminar flaws in the weld overlay evaluated to ensure load distribution meets NB-3200. Same as N-504-2 for shrinkage and evaluation of other existing flaws.

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Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 4 COMPARISON OF PROPOSED ALTERNATIVE WITH N-504-2 N-504-2 PROPOSED ALTERNATIVE (i) No specific reference given for 3.0 Examination and Inspection acceptance examination of the weld Examinations in the proposed alternative shall overlay. Acceptance criteria of the be met in lieu of all other exams. NDE Construction Code and Section III would methods to IWA-2200 except as specified in be applicable. (Causes problems with the case. NDE personnel qualified to IWA-volumetric acceptance criteria since 2300. UT procedures and personnel qualified construction criteria based on RT to Section XI, Appendix VIII.

examination rather than UT examination.

Also presents difficulty in determining (a) Acceptance Examinations-Surface finish applicable criteria for laminar flaws in the 250 micro-inch (or 225 RA) and flatness overlay ) sufficient to allow adequate examination in accordance with Appendix VIII procedures.

Preservice Exams to the methods of IWB- PT the overlay and 1/2-inch on either side of 2200. Exam procedures shall be specified in the overlay. Acceptance standards for the the Repair Program. Acceptance standard- PT of the weld overlay, meet weld IWB-3514-2 (planar flaws). UT exams to Construction Code criteria or NB-5300.

verify integrity of new applied weld Base material, meet base material criteria reinforcement. Include upper 25% of pipe or NB-2500. A 48-hour hold time after the wall in the examination. third layer is completed is imposed when ambient temperature temperbead welding is used. UT examination for acceptance Figure 1 shows the examination volume.

IWB-3514-2 for planar flaw acceptance.

IWB-3514-3 for laminar flaw acceptance with additional limitation not to exceed 10%

of the surface area and no linear dimension in excess of 3 inches.

Reduction in coverage limited to 10%.

Criteria for radial planar flaw size in the uninspected volume for IWB-3640 evaluation.

(b) Preservice Examinations Figure 2 defines the examination volume. Angle beam exam parallel and perpendicular to piping axis. Scan in four directions to locate and size flaws. Acceptance criteria IWB-3514-2 for the overlay. Wall thickness tw is the thickness of the overlay. Flaws in outer 25% of base material meet design requirements of 2.0.

E1-17

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 4 COMPARISON OF PROPOSED ALTERNATIVE WITH N-504-2 N-504-2 PROPOSED ALTERNATIVE (c) Inservice Examinations Use Q-4300 of Appendix Q to the 2004 Edition of Section XI with Addenda through 2005.

(d) Additional Examinations Use Q-4300 of Appendix Q to the 2004 Edition of Section XI with Addenda through 2005.

(h) System Hydrostatic Test if pressure 4.0 Pressure Testing boundary penetrated (leak). System Leakage System Leakage Test per IWA-5000 Test if pressure boundary not penetrated (no leak).

(k) VT-3 of snubbers, supports and restraints There are no snubbers, supports, or whip after welding restraints.

(l) Reference to other applicable requirements IWA-4000 requirements would be met unless an of IWA-4000 alternative provided (m) Use of case to be documented on an NIS- 5.0 Documentation 2 form Use of case to be documented on an ASME Form NIS-2 (or ASME Form NIS-2A).

E1-18

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 5 COMPARISON OF APPENDIX 1 OF PROPOSED ALTERNATIVE WITH N-638-1 APPENDIX 1 OF THE PROPOSED N-638-1 ALTERNATIVE Code Case N-638-1 provides rules for Appendix 1 is invoked in by 1.(b) of the alternative automatic or machine GTAW temperbead for use of ambient temperature temperbead welding without pre-heat or post weld heat welding as an alternative to the post weld heat treatment. The case covers similar and treatment requirements of the Construction Code dissimilar welding for cavity and overlay and Owners requirements. The appendix provides repairs. The code case permits the use of the ambient temperature temperbead requirements NDE examinations in accordance with the applicable to dissimilar metal weld overlay repairs.

case in lieu of those in the Construction Code. NDE requirements are in lieu of the Construction This case has a broader scope of use then Code and were covered in Section 3.0 of the Appendix 1. alternative.

1.0 General Requirements 1.0 General Requirements Scope of welds in the Reply (a) Scope of welds. Same as N-638-1 (a) Max area of finished surface of the weld (b) Surface area limitation 300 square inches over limited to 100 square inches and half of the the ferritic material. (Note: Code Case N-638-3 ferritic base metal thickness. (Note: the depth which has been approved by ASME but has not requirement is for the ferritic material. There is been issued in Supplement 9. Residual stress no need to limit either surface area or depth analyses results show that stresses for 100 square for welding on austenitic SS or nickel alloys inches through 500 square inches surface area since no post weld heat treatment is required.) overlays very similar.)

(b) (c) (d) (e) (f) (c) (d) (e) (f) (g) same as requirements listed for N-638-1 1.0 Welding Qualifications 2.0 Welding Qualifications The welding procedures and welding The welding procedures and welding operators operators shall be qualified in accordance shall be qualified in accordance with Section with Section IX and the requirements of IX and the requirements of 2.1 and 2.2 2.1 and 2.2 2.1 Procedure Qualification Sections (a) 2.1 Procedure Qualification (d) (e) (f) (g) Sections (a) (b) (c) (d) (e) same as in N-638-1 for equivalent paragraphs.

Section (h) Equivalent paragraph not in Appendix 1.

Section (i) Section (f) same as (i) from N-638-1.

Section (j) Section (g) changed the first sentence adding lateral expansion in front of value both at the beginning and end of the sentence. Additional provisions as follow E1-19

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 5 COMPARISON OF APPENDIX 1 OF PROPOSED ALTERNATIVE WITH N-638-1 APPENDIX 1 OF THE PROPOSED N-638-1 ALTERNATIVE were added:

However if the average lateral expansion value of the HAZ Charpy V-notch specimens is less than the average value of the unaffected base metal specimen and the procedure qualification meets all other requirements of this appendix, either of the following shall be performed:

(1) The welding procedure shall be requalified.

(2) An Adjustment Temperature for the procedure qualification shall be determined in accordance with the applicable provisions of NB-4335.3 of Section III, 2001 Edition with 2002 Addenda. RTndt or lowest service temperature of the materials for which the welding procedure will be used shall be increased by a temperature Section (b) Provisions for welding in a equivalent to that of the Adjustment pressurized environment Temperature. This is identical wording to N-638-2, which has been approved by Section (c) Provisions to address ASME.

radiation effects Not included for overlays in Appendix 1.

Not included in Appendix 1. Thermal neutron limitation imposed in the proposed alternative.

1.1 Performance Qualification 2.2 Performance Qualification Welding operators shall be qualified in Welding operators shall be qualified in accordance with Section IX. accordance with Section IX.

3.0 Welding Procedure Requirements 3.0 Welding Procedure Requirements (no corresponding section) (e) Section added to clarify temperature measurement requirements. This is identical wording to N-638-2, which has been approved by ASME.

(a) (b) (c) (a) (b) (c) same as N-638-1 except last two E1-20

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 5 COMPARISON OF APPENDIX 1 OF PROPOSED ALTERNATIVE WITH N-638-1 APPENDIX 1 OF THE PROPOSED N-638-1 ALTERNATIVE sentences deleted in (c) from N-638-1 since not applicable to this proposed alternative.

(d) (d) same as N-638-1 but the following added:

The interpass temperature of QW-406.3 need not be applied. This is identical wording to N-638-2, which has been approved by ASME.

(no corresponding section) (e) Section added to clarify temperature measurement requirements. This is identical wording to N-638-2, which has been approved by ASME.

(e) (f) same as (e) from N-638-1 4.0 Examination Examination and Inspection is shown in Section 3 The final weld surface and the band around of the proposed alternative.

the area defined in paragraph 1.0(d) of N-638-1 shall be examined using surface and ultrasonic methods when the completed weld has been at ambient temperature for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

5.0 Documentation Documentation is shown in Section 5 of the proposed alternative.

(no corresponding section) Pressure Testing is shown in Section 4 of the proposed alternative.

E1-21

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 6 FIGURE 1 EXISTING WELD CONFIGURATION E1-22

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 6 (Continued)

FIGURE 2 OVERLAY CONFIGURATION

1. Component surface is to be examined by dye penetrant method and accepted as clean prior to overlay application.
2. In the event that the original component surface does not pass the note 1 requirements, the final deposited temper bead weld layer is to be examined by dye penetrant method and accepted as clean before proceeding with subsequent layers.
3. Weld overlay wire shall be ERNiCrFe-7 (Alloy 52), or equivalent.
4. The design thickness (0.25 inch) is the minimum thickness beyond the first PT clean surface or layer.
5. Apply as many layers as required to achieve the design overlay thickness t.
6. Design thickness includes no allowance for surface conditioning operations to facilitate UT inspection.
7. Design length is that required for structural reinforcement; greater length may be required for effective UT inspection. This is to be determined in the field.

E1-23

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 7 JUSTIFICATION FOR PERFORMING EXAMINATIONS 48 HOURS AFTER THE COMPLETION OF THE THIRD WELD LAYER American Society of Mechanical Engineers (ASME) Code,Section XI, Code Case N-638-1 requires (when ambient temperbead welding is used over ferritic materials) that surface and ultrasonic examinations be performed when the completed weld has been at ambient temperature for least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. This delay was provided to allow sufficient time for hydrogen cracking to occur (if it is to occur) in the heat affected zone (HAZ) of ferritic materials prior to performing examinations, to ensure detection by non-destructive examinations (NDE).

However, based on research and industry experience, EPRI has provided a technical basis for starting the 48-hour hold after completion of the third temperbead weld layer rather than waiting for the weld overlay to cool to ambient temperature. Weld layers beyond the third layer are not designed to provide tempering to the ferritic HAZ during ambient temperature temperbead welding. EPRI has documented their technical basis in Technical Update report 1013558, Repair and Replacement Applications Center: Temperbead Welding Applications 48-Hour Hold Requirements for Ambient Temperature Temperbead Welding (ADAMS Accession No. ML070670060). The technical data provided by EPRI in their report is based on testing performed on SA-508, Class 2 low-alloy steels, which is the nozzle material. After evaluating all of the issues relevant to hydrogen cracking such as microstructure of susceptible materials, availability of hydrogen, applied stresses, temperature, and diffusivity and solubility of hydrogen in steels, EPRI concluded that: ...[t]here appears to be no technical basis for waiting the 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after cooling to ambient temperature before beginning the NDE of the completed weld.

There should be no hydrogen present, and even if it were present, the temperbead welded component should be very tolerant of the moisture... EPRI also notes that over 20 weld overlays and 100 repairs have been performed using temperbead techniques on low alloy steel components over the last 20 years. During this time, there has never been an indication of hydrogen cracking by the non-destructive examinations performed after the 48-hour hold or by subsequent ISI examinations.

In addition, the ASME database, C&S Connect, for Code Case N-638-4 contains background material consisting of a Technical Basis Paper to support the 48-hour hold time alternative. The Technical Basis Paper (ADAMS Accession No. ML070790679) points out that the introduction of hydrogen to the [ferritic] HAZ is limited to the first weld layer since this is the only weld layer that makes contact with the [ferritic] base material. While the potential for the introduction of hydrogen to the [ferritic] HAZ is negligible during subsequent weld layers, these layers provide a heat source that accelerates the dissipation of hydrogen from the [ferritic] HAZ in non-water backed applications. The Technical Basis Paper concludes that there is sufficient delay time to facilitate the detection of potential hydrogen cracking when NDE is performed 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after completion of the third weld layer.

Furthermore, the solubility of hydrogen in austenitic materials such as Alloy 52M is much higher than that of ferritic materials while the diffusivity of hydrogen in austenitic materials is lower than that of ferritic materials. As a result, hydrogen in the ferritic HAZ tends to diffuse into the austenitic weld metal, which has a much higher solubility for hydrogen. This diffusion process is enhanced by heat supplied in subsequent weld layers.

E1-24

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 7 JUSTIFICATION FOR PERFORMING EXAMINATIONS 48 HOURS AFTER THE COMPLETION OF THE THIRD WELD LAYER (Continued)

Based on this information, SNC concludes that performing NDE 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the third weld layer is installed will provide an acceptable level of quality and safety. As a precedent see the April 6, 2007, safety evaluation for Arkansas Nuclear One, Unit 1 (TAC NO. MD4019) and the December 19, 2007 safety evaluation for Farley Nuclear Plant Units 1 and 2 (TAC NOS.

MD6304 and MD6305).

E1-25

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 8 Q-4300 EXAMINATION REQUIREMENTS Q-4300 Inservice Examination Requirements (a) The weld overlay examination volume in Fig. Q-4300-1 shall be added to the inspection plan and shall be ultrasonically examined during the first or second refueling outage following application.

(b) The weld overlay examination volume in Fig. Q-4300-1 shall be ultrasonically examined to determine if any new or existing cracks have propagated into the upper 25% of the pipe base material or into the overlay. The angle beam shall be directed perpendicular and parallel to the pipe axis, with scanning performed in four directions.

Modified Q-4300 Inservice Flaw Evaluation Requirements (a) Flaws characterized as SCC in the Alloy 52/152 weld overlay are unacceptable and the use of IWB-3514-2 and IWB-3640 for SCC evaluation in the Class 1 overlay material is prohibited.

(b) For non-SCC flaws in the Alloy 52/152 overlay, Table IWB-3514-2 must be used to evaluate recordable indications prior to the use of the acceptance criteria of IWB-3600. If the requirements of Table IWB-3514-2 cannot be satisfied, the acceptance criteria of IWB-3600 shall be satisfied. For unacceptable indications, the weld overlay (or the portion of the weld overlay containing the unacceptable indication) shall be removed and corrected by a repair/replacement activity in accordance with IWA-4000.

(c) If examinations reveal crack growth or new cracking in the upper 25% of the original weld or base materials, the as-found flaw (postulated 75% through wall, plus the portion of the flaw in the upper 25%) will be used to re-evaluate the crack growth analysis. The size of all flaws will be projected to the end of the design life of the overlay. Crack growth, including both stress corrosion and fatigue crack growth, shall be evaluated in the materials in accordance with IWB-3640. If the flaw is at or near the boundary of two different materials, evaluation of flaw growth in both materials is required. For unacceptable indications, the weld overlay shall be removed, including the original defective piping weldment, and corrected by a repair/replacement activity in accordance with IWA-4000.

Modified Q-4300 Re-examination Requirements (a) Weld overlay examination volumes that show no indication of crack growth or new cracking shall be placed into a population to be examined on a sampling basis. Twenty-five percent of this population shall be examined once every ten years.

E1-26

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 8 Q-4300 EXAMINATION REQUIREMENTS (Continued)

(b) If inservice examinations reveal acceptable crack growth or new cracking in the upper 25% of the original weld or base materials, the weld overlay examination volume shall be reexamined during the first or second refueling outage following discovery of the growth or new cracking. Weld overlay examination volumes that show no additional indication of crack growth or new cracking shall be placed into a population to be examined on a sample basis. Twenty-five percent of this population shall be examined once every ten years.

(c) If inservice examinations reveal acceptable non-SCC flaws in the overlay material, the weld overlay examination volume shall be reexamined during the first or second refueling outage following discovery of the growth or new cracking. Weld overlay examination volumes that show no additional indication of crack growth or new cracking shall be placed into a population to be examined on a sample basis. Twenty-five percent of this population shall be examined once every ten years.

Q-4310 Additional Examinations If inservice examinations reveal an unacceptable indication, crack growth into the weld overlay design thickness, or axial crack growth beyond the specified examination volumes, additional weld overlays, equal to the number scheduled for the current inspection period, shall be examined prior to return to service. If additional unacceptable indications are found in the second sample, a total of 50% of the total population of weld overlays shall be examined prior to operation. If additional unacceptable indications are found, the entire remaining population of weld overlays shall be examined prior to return to service.

E1-27

Enclosure 1 SOUTHERN NUCLEAR OPERATING COMPANY ISI-ALT-08-01, VERSION 1.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

APPLICATION OF A DISSIMILAR METAL WELD FULL-STRUCTURAL WELD OVERLAY HATCH NUCLEAR PLANT UNIT 1 APPENDIX 8 Q-4300 EXAMINATION REQUIREMENTS (Continued)

E1-28

Edwin I. Hatch Nuclear Plant Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(i)

Application of a Dissimilar Metal Weld Full-Structural Weld Overlay Enclosure 2 ISI-GEN-ALT-08-01, Version 1.0 List of Regulatory Commitments

Enclosure 2 ISI-GEN-ALT-08-01, Version 1.0 List of Regulatory Commitments The following table identifies those actions committed by Southern Nuclear Operating Company in this document for Edwin I. Hatch Nuclear Plant. Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments.

Type Scheduled Commitment Completion Date One-Time Continuing (If Required)

Action Compliance Within 14 days SNC will report to the NRC (1) the after ultrasonic examination results of the weld overlay examination of and (2) a discussion of any repairs to the X weld overlay overlay material and/or base metal and installations the reason for repair.

SNC will report to the NRC the results of the stress analysis report, which will include results showing that the requirements of Subarticles NB-3200 and Within 90 calendar NB-3600 of the ASME Code,Section III days of the are satisfied. The stress analysis will also completion of the include results showing that the X refueling outage requirements of IWB-3000 of the ASME Code,Section XI, are satisfied. The results will show that the postulated crack including its growth in the nozzles would not adversely affect the integrity of the overlaid welds.

E2-1

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