ML062430314

Fourth Ten Year Inservice Inspection Interval Request for Relief No. 06-ON-004

ML062430314
Person / Time
Site:	Oconee
Issue date:	08/24/2006
From:	Brandi Hamilton Duke Energy Carolinas, Duke Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
06-ON-004
Download: ML062430314 (27)

Text

Duke BRUCE HHAMILTON Vice President fEnergy Oconee Nuclear Station Duke Energy Corporation ONO] VP / 7800 Rochester Highway Seneca, SC 29672 864 885 3487 864 885 4208 fax bhhamilton@duke-energy.com August 24, 2006 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Subject:

Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC (Duke)

Oconee Nuclear Station, Units 1, 2, 3 Docket Nos. 50-269,-270,-287 Fourth Ten Year Inservice Inspection Interval Request for Relief No. 06-ON-004 Pursuant to 10 CFR 50.55a(a)(3)(i), Duke hereby requests NRC approval to use alternatives to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI inservice inspection (ISI) requirements for the Oconee Nuclear Station, Units 1, 2, and 3. This proposed alternative approach is to support application of full structural weld overlays on various pressurizer nozzle-to-safe end welds and will provide an acceptable level of quality and safety.

This request is needed to support work beginning with the Oconee Unit 1 EOC 23 refueling outage, which is scheduled to start October 7, 2006.

The installation of the weld overlays will be conducted in accordance with the 1998 Edition through 2000 Addenda of ASME Code,Section XI, IWA-4000 and ASME approved Code Cases N-504-2 and N-638-1 with modifications as described in this request. These Code Cases are listed as conditionally acceptable for use in NRC Regulatory Guide 1.147, Revision 14.

Additionally, Duke is required to implement Appendix VIII of the ASME Code,Section XI, 1998 Edition with the 2000 Addenda, which contains ultrasonic examination performance qualification requirements under Supplement 11 for a completed full structural weld overlay repair. In lieu of these ASME Code ultrasonic qualification requirements, Duke proposes to use the alternative qualification as administered by the Performance Demonstration Initiative (PDI) for the qualification of the ultrasonic examination of the full structural weld overlay repair, and the examination of the dissimilar metal welds.

www. duke-energy. corn

U. S. Nuclear Regulatory Commission August 24, 2006 Page 2 Use of the proposed alternative is based on the PDI approved techniques and procedures also described in this request. The detailed relief request is provided as Enclosure 1 to this letter. It contains a comprehensive set of criteria that outline the proposed Oconee Units 1, 2, and 3 full structural weld overlays. The relief request provides alternatives and modifications to the ASME Code requirements and Code Cases N-504-2 and N-638-1 that Duke has determined will be necessary to perform this repair.

Similar relief requests have been previously approved for Three Mile Island Nuclear Station Unit 1, on July 21, 2004; Cooper Nuclear Station on March 4, 2005; Susquehanna Steam Electric Station Unit 1, on June 22, 2005; Donald C.

Cook Nuclear Plant Unit 1 on June 27, 2005; Calvert Cliffs Nuclear Power Plant Unit 2 on July 20, 2005; and Millstone Power Station Unit 3 on January 20, 2005.

In addition, a similar relief request was submitted by Duke for both McGuire and Catawba Nuclear Stations on July 27, 2006.

Duke requests verbal approval of this relief request prior to October 7, 2006 to support the Oconee Unit 1 fall 2006 refueling outage.

This relief request contains one regulatory commitment. Prior to entry into Mode 4, from the Oconee Unit 1 outage in the fall of 2006, a summary of the results of the stress analyses demonstrating that the preemptive full structural weld overlay will not hinder the components from performing their design function will be submitted to the NRC. These results are expected to be bounding for all three Oconee units.

If there are any questions or further information is needed you may contact R. P.

Todd at (864) 885-3418.

Vet lyu rs, B.H.HAito "Ol Site Vice President Enclosure

U. S. Nuclear Regulatory Commission August 24, 2006 Page 3 xc w/att: Dr. William D. Travers Administrator, Region II U.S. Nuclear Regulatory Commission Atlanta Federal Center 61 Forsyth St., SWW, Suite 23T85 Atlanta, GA 30303 L. N. Olshan, Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 xc(w/o attch):

D. W. Rich Senior NRC Resident Inspector Oconee Nuclear Station Mr. Henry Porter Division of Radioactive Waste Management Bureau of Land and Waste Management SC Dept. of Health & Environmental Control 2600 Bull St.

Columbia, SC 29201

Request No. 06-ON-004 Enclosure I ProposedAlternative In Accordance with 10 CFR 50.55a(a)(3)(i)

- Alternative ProvidesAcceptable Level of Quality and Safety -

Duke Energy Corporation Oconee Units 1, 2 & 3 Request for Alternative 06-ON-004 CONTENTS 1.0 ASME CODE COMPONENTS AFFECTED .......................................................... 2 2.0 APPLICABLE CODE EDITION AND ADDENDA ............................................... 3 3.0 APPLICABLE CODE REQUIREMENTS ............................................................... 3 4.0 REASON FOR THE REQUEST ............................................................................... 3 5.0 PROPOSED ALTERNATIVES AND BASIS FOR USE ........................................ 4 6.0 WELD OVERLAY DESIGN AND VERIFICATION ............................................. 6 7.0 DURATION OF THE PROPOSED ALTERNATIVES ........................................... 7 8.0 PRECEDENTS ...................................................................................................... 7

9.0 REFERENCES

....................................................................................................... 8

10.0 CONCLUSION

....................................................................................................... 9 List of Figures Figure 1: Pressurizer Surge Nozzle Weld Overlay (Typical) ................................................... 10 Figure 2: Hot Leg Surge Nozzle Weld Overlay (Typical) ............................................................ I1 Figure 3: Pressurizer Spray Nozzle Weld Overlay (Typical) ................................................... 12 Figure 4: Pressurizer Safety/Relief Nozzle Weld Overlay (Typical) ......................................... 13 List of Tables T able 1........................................................................................................................................... 15 Modifications To Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q R equirem ents ......................................................................................................................... 15 Table 2 ........................................................................................................................................... 17 Alternatives to Appendix VIII, Supplement II ....................................................................... 17 T able 3 ........................................................................................................................................... 23 Modifications to Code Case N-638-1 ....................................................................................... 23 Page 1 of 24

Request No. 06-ON-004 Enclosure I 1.0 ASME CODE COMPONENTS AFFECTED System: Reactor Coolant System Component Number:

OcneeI Description .- Size : Weld Number llCmment.Z iPressurizerISurge nozzle to safe end 10.75" OD I -PZR-WP23 ICS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Spray nozzle to safe end 14.5" OD 1-PZR-WP45iCS nozzle/Alloy 82-182 weld/A600 safe end Pressurizer' Relief nozzle to flange _ 4.5" OD I-PZR-WP9i- itCs nozzle/Alloy 82-182 weld/SS flange

_PressurizerSafety nozzle to flange 4.5" OD I-PZR-WP91-2 iCS nozzle/Alloy 82-182 weld/SS flange Pressurizer:°Safety nozzle to flange 4.5" OD I-PZR-WP91-3 'CS nozzle/Alloy 82-182 weld/SS flange RC Pipe :Spray safe end to pipe :4.5" OD I-PSP-- A600 safe end/ Alloy 82-182 weld SS pipe .

RC Pipe Surge line to Hot leg 11.5" OD I-PSL-10 :Alloy 82-182 butter/ Alloy 82-182 weld/SS pipe

',Nozzle I-PHA-17 :CS Nozzle/alloy 82-182 butter 1cneDescription I 1 PressurizerISurge

.nit2d nozzle to safe end Sie, 110.75" OD Wl ubr 12-PZR -WP23 Commnent",

CS nozzle/Allo 82-182 weld/SS safe end 7 7i.

PressurizerISpray nozzle to safe end 14.5" OD !2-PZR-WP45.JCS nozzle/Alloy 82-182 weld/A600 safe end iPressurizerlRelief nozzle to flange _ 4.5-" OD .2-PZR-WP91-1 ICS nozzle/Alloy 82-182 weld/SS flange PressurizeriSafety nozzle to flange 14.5" OD 12-PZR-WP91-2 1CS nozzle/Alloy 82-182 weld/SS flange ressurizerSafynozzle to flange ,4.5" OD ';2-PZR-WP91-3 1CS nozzle/Alloy 82-182 weld/SS flange .

RCPipe !Spray safe end to pipe 4.5" OD 2-PSP-I A600 safe end/ Alloy 82-182_weldSSppe

,RC Pipe :Surge line to Hot leg 11.5" OD 2-PSL-10 Alloy 82-182 butter/ Alloy 82-182 weld/SS pipe Nozzle . 2-PHB-17 iCS Nozzle/alloy 82-182 butter Oconee Description Size... Weld Number ] rCommen0)-,,  :

lPressurizer1 Surge nozzle to safe end 10.75" OD 13-PZR -WP23 CS nozzle/Alloy 82-182 weld/SS safe end Pressurizer'Sp*ay nozzle to safe end 4.5" OD J3-PZR-WP45 ICS nozzle/Alloy 82-182 weld/A600 safe end

!Pressurizer Relief nozzle to flange 4.5" OD :3-PZR-WP91-1 ICS nozzle/Alloy 82-182 weld/SS flange iPressurizeriSafety nozzle to flange 4.5" OD i3-PZR-WP91-2 ICS nozzle/Alloy 82-182 weld/SS flange __.....

!Pressurizer Safety nozzle to flange 14.5" OD 3-PZR-WP91-3 1CS nozzle/Alloy 82-182 weld!SS flange.

RC Pipe ;Spray safe end to pipe 14 .5" OD PSP-1 IA600 safe end/ Alloy 82-182 weld SS pipe IRC Pipe 'Surge line to Hot leg 11.5 OD

3-PSL-10 Alloy 82-182 butter/ Alloy 82-182 weld/SS pipe Nozzle :3-PHB-17 CS Nozzle/alloy 82-182 butter (1) CS = A-508 Class I-PZR nozzles; A105 Gr 2 - Hot leg nozzle.

SS = Type 316 austenitic stainless steel Code Class: Class 1 Examination Category: B-F; B-J Code Item Number: B5.40; B9.11I Page 2 of 24

Request No. 06-ON-004 Enclosure 1 2.0 APPLICABLE CODE EDITION AND ADDENDA Inservice Inspection:

ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda Design and Fabrication:

ASME Boiler and Pressure Vessel Code,Section III, Subsection A, 1965 Edition through 1967 Addenda Duke Welding Program:

ASME Boiler and Pressure Vessel Code,Section III, 1989 Edition No Addenda 3.0 APPLICABLE CODE REQUIREMENTS ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda, Article IWA-4000, "Repair/Replacement Activities" ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda, Appendix VIII, Supplement 11, "Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds" Code Case N-504-2 with requirements of ASME Code,Section XI, Nonmandatory Appendix Q, "Weld Overlay Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping Weldments" Code Case N-638-1, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique".

4.0 REASON FOR THE REQUEST Dissimilar metal welds (DMW) made with nickel alloys 82 and 182 have been shown to be susceptible to primary water stress corrosion cracking (PWSCC) degradation in components that are subjected to higher operating temperatures. Structural weld overlays have been used for several years on piping of both boiling water reactors and pressurized water reactors to arrest the growth of existing flaws while establishing a new structural pressure boundary. No evidence of PWSCC has been found in the welds of the Oconee pressurizer; however, PWSCC is difficult to detect in DMW except when the inspection is performed in accordance with the stringent requirements of ASME Section XI, Appendix VIII. Some of the DMW included in this request for relief have been evaluated and found not to meet the surface or geometric requirements of Appendix VIII. The feasibility of modifying the geometry to an acceptable configuration has not been established. Rather than risk multiple cycles of inspection and modification, Duke is proposing to take a proactive approach to apply a Page 3 of 24

Request No. 06-ON-004 Enclosure I preemptive full structural weld overlay (PWOL) to the dissimilar metal welds of the pressurizer components listed in Section 1.0 of this request.

Currently, there are no comprehensive criteria for a licensee to apply a full structural weld overlay to DMW constructed of Alloy 82/182 weld material. Neither the latest NRC approved edition nor the edition of ASME Section XI used for the Oconee Units 1, 2, & 3 repair/replacement program, contains the needed requirements for this type of repair.

Repair/replacement activities associated with a full structural weld overlay repair of this type are required to address the materials, welding parameters, ALARA concerns, operational constraints, examination techniques, and procedure requirements. Similar nozzle-to-safe end weld overlays have been applied to other plants since 1986 with no problems identified.

5.0 PROPOSED ALTERNATIVES AND BASIS FOR USE Pursuant to 10CFR 50.55a(a)(3)(i), an alternative to the requirements listed in Section 3.0 above is requested on the basis that the proposed alternative will provide an acceptable level of quality and safety. Attachment 1, Tables 1, 2 and 3, included as a part of this request for relief, provides details of relief requested from each of these requirements.

A PWOL is proposed for each of the pressurizer welds identified in Section 1.0 above. The overlays will extend around the full circumference of the nozzle-to-safe end and safe end to piping welds, as illustrated in Figures 1 through 4. The entire safe end for the Spray line is included since the safe end is fabricated from Alloy 600. The full structural weld overlays are sized to satisfy the ASME Code,Section III requirements without crediting the existing welds.

The proposed weld overlay design is consistent with the requirements of ASME Code Case N-504-2 and Section XI, Nonmandatory Appendix Q, with the modifications noted in Table

1. The provisions of Appendix Q must be met as a condition of acceptance of the Code Case by NRC Regulatory Guide 1.147, Revision 14. The specific thickness and length are computed according to the guidance provided in Code Case N-504-2 and Appendix Q. The overlay will completely cover the Alloy 82/182 welds and adjacent Alloy 600 safe end for the Spray line with alloy 52M/52MS material that is highly resistant to PWSCC.

The length of the full structural weld overlay is sized for inspection of the volume shown in Appendix Q, Fig Q-4300-1. This volume extends 1/2-inch beyond the susceptible weld and includes the outer 25% of the original wall thickness. The length of the PWOL is extended and blended into the carbon steel (CS) nozzle outer diameter to permit ultrasonic testing (UT) of the weld and to minimize stress concentration on the nozzle outer diameter. The outside diameter of the nozzle is larger than that of the adjacent component; therefore, the PWOL thickness on the component is increased to allow a smooth transition surface for UT. The final structural weld overlay length and thickness after taking into consideration the UT requirements will exceed the length required for a full structural weld overlay repair in accordance with Case N-504-2 and Appendix Q.

Page 4 of 24

Request No. 06-ON-004 Enclosure I Implementation of Section XI, Subsection, IWA-4540(a)(2) for a system leakage test requires performance of NDE in accordance with the methods and acceptance criteria of the applicable Subsection of the 1992 or later Edition of ASME Section III. Alternately, the NDE requirements of Appendix Q will be followed for the required NDE. The bases for these alternatives are shown as needed in Table 1.

Appendix Q, Section 4000 requires ultrasonic procedures and personnel to be qualified in accordance with ASME Code,Section XI, Appendix VIII. Ultrasonic examination of the completed PWOL will be accomplished in accordance with Section XI, Appendix VIII, Supplement 11, with alternatives to comply with the Performance Demonstration Initiative (PDI) program as shown in Table 2.

The PWOL will be applied over portions of the CS nozzles. The Construction Code requires either pre-heat or post-weld heat treatment after welding depending on the carbon content or base material thickness. As an alternative to pre-heat or post-weld heat treatment, the overlay will be implemented in accordance with Code Case N-638-1 with the modifications noted in Table 3 of Attachment 1. Code Case N-638-1 was conditionally approved for generic use in NRC Regulatory Guide 1.147, Revision 14, and was developed for welding similar and dissimilar metals using the ambient temperature machine GTAW temper bead technique.

This Code Case specifies a limit of 100 square inches for the surface area of temper bead weld over the ferritic material. The weld surface areas over ferritic material for the subject weld overlays are expected to be approximately 125 square inches, 70 square inches, 30 square inches, and 30 square inches, for the pressurizer surge line nozzle, hot leg surge line nozzle, safety and relief line nozzles, and spray line nozzles, respectively.

Code Case N-638-3, recently approved by ASME, increases the limit for temper bead welding over ferritic material. The technical basis for this revision is contained in a white paper that was submitted to the Code Committee as part of the ASME Code approval process. The white paper indicates the original limit of 100 square inches in Code Case N-638-1 was an arbitrary limit and goes on to justify the application of overlays up to 500 square inches on ferritic low alloy steel. The white paper was also submitted to the NRC as a part of a relief request by Constellation Energy Generation Group (Adams Accession Number, ML060240110). The white paper cites evaluations of a 12 inch diameter nozzle weld overlay to demonstrate adequate tempering of the weld heat affected zone (Section 2a of the white paper), residual stress evaluations demonstrating acceptable residual stresses in weld overlays ranging from 100 to 500 square inches (Section 2b of the white paper), and service history in which weld repairs exceeding 100 square inches were NRC approved and applied to DMW nozzles in several BWRs and three PWRs (Section 3c of the white paper). Some of the cited repairs are greater than 15 years old, and have been inspected several times with no evidence of any continued degradation. The revised limit far exceeds the estimated 125 square inches to be applied to the Oconee surge nozzles and so provides a conservative basis for application of the proposed PWOL.

Inspections required by Code Case N-638-1 will be performed in accordance with Code Case N-504-2 and Section XI, Appendix Q. Code Case N-638-1 applies to any type of welding where a temper bead technique is to be employed and is not specifically written for a weld Page 5 of 24

Request No. 06-ON-004 Enclosure I overlay repair. The specific overlay inspections required by Code Case N-504-2 will detect any discontinuities that might result from application of the PWOL and will provide assurance equal to that provided by the inspections required in Code Case N-638-1.

Temperature monitoring required by Code Case N-638-1 will be performed using temporarily attached pyrometers and manual data recording in lieu of thermocouples and recording equipment required by IWA-4610(a) of Section XI. The adequacy of contact pyrometers for this purpose has been recognized by ASME and this option is included in Code Case N-638-3.

This exception has been permitted by the NRC in the past (see precedent 6 in Para 8.0 below).

As described in Table 3, use of pyrometers will provide acceptable temperature monitoring for application of the PWOL.

In summary, this letter requests relief from portions of the applicable ASME Code and Code Cases approved for use by the NRC. There are no new or different approaches in this overlay design that are considered first of a kind or inconsistent with previous applications. The overlay is designed as a full structural overlay in accordance with ASME Code Case N-504-2 and Section XI, Nonmandatory Appendix Q.

6.0 WELD OVERLAY DESIGN AND VERIFICATION The design of these weld overlays takes guidance from the requirements of ASME Code Case N-504-2, and Code Case N-638-1, with modifications as described above in Section 5.0 and in the attached tables. The weld overlays will be demonstrated to be long-term repairs and mitigation of PWSCC based on analyses that will be completed before plant restart. The fundamental design basis for full structural weld overlays is to maintain the original safety margins of the welds, with no credit taken for the underlying PWSCC susceptible weldments.

Analyses are performed to demonstrate that the overlay designs meet the requirements of ASME Code,Section XI, IWB-3640, in addition to the structural requirements of ASME Code Case N-504-2 for full structural weld overlays. No credit is taken for the diluted first layer of the overlays over the PWSCC susceptible weldments. Each required analysis will be bounding for the three units included in this request for relief. Following is a listing of the analyses and verifications that will be performed for each overlay.

1. Nozzle specific stress analyses will be performed to establish a residual stress profile in the nozzle. Severe ID weld repairs have been assumed that effectively bound any actual weld repairs to the nozzle. The weld overlay is subsequently applied to simulate the final residual stress profile. Post weld overlay residual stresses at normal operating conditions will then be shown to result in beneficial compressive stresses on the inside surface of the components, further assuring that crack growth into the overlay is highly unlikely.

2. Fracture mechanics analyses will also be performed to predict crack growth, assuming that cracks exist that are equal to or greater than the thresholds of the NDE techniques to be used on the nozzles. Potential crack growth will be evaluated due to PWSCC as well as due to fatigue crack growth in the original DMW. The crack growth analyses Page 6 of 24

Request No. 06-ON-004 Enclosure 1 will consider all design loads and transients, plus the post weld overlay residual stress distributions, and will demonstrate that cracks will not grow beyond the original DMW thickness for the time period until the next scheduled inservice inspection.

3. The analyses will demonstrate that application of the weld overlays does not impact the conclusions of the existing nozzle Stress Reports. ASME Code,Section III stress and fatigue criteria will be met, as spelled out in ASME Code Case N-504-2.

4. Shrinkage will be measured during the overlay application. Shrinkage stresses at other locations in the piping systems arising from the weld overlays will be demonstrated not to have an adverse effect on the systems. Clearances of affected support and restraints will be checked after the overlay repair, and will be reset within the design ranges as required.

5. The total added weight on the piping systems due to the overlays will be evaluated for potential impact on piping system stresses and dynamic characteristics.

6. The as-built dimensions of the weld overlays will be measured and evaluated to demonstrate that they equal or exceed the minimum design dimensions of the overlays.

Summaries of the results of the analyses listed in items I through 3 above will be submitted to the NRC prior to entry into mode 4 during the restart of Oconee Unit 1 during the EOC 23 (Fall 2006) outage. Items 4 through 6 above will be completed after final as-built documentation is processed into the Oconee Document Management System.

7.0 DURATION OF THE PROPOSED ALTERNATIVES These structural weld overlays will remain in place for the design life of the repair that is defined by the evaluation required in paragraph (g) of Code Case N-504-2 and corresponding requirements in Nonmandatory Appendix Q. The overlays will be performed during the fourth inspection interval for the three Oconee units. The interval start and end dates for these units are:

Oconee Unit 1-Start: 01/01/2004 End: 07/15/2013 Oconee Unit 2-Start: 09/09/2004 End: 09/09/2014 Oconee Unit 3-Start: 01/02/2005 End: 12/16/2014 The Code of Record for inservice inspection during these intervals is the ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda for all three units.

8.0 PRECEDENTS

1. Letter from Richard J. Laufer, NRC, to Christopher M. Crane, AmerGen, "Three Mile Island Nuclear Station, Unit I (TMI-1) Request for Relief from Flaw Removal, Heat Treatment, and Nondestructive Examination Requirements for the Third 10-year Page 7 of 24

Request No. 06-ON-004 Enclosure I Inservice Inspection (ISI) Interval (TAC.No. MCI201)," Accession Number ML041670510, dated July 21, 2004.

2. Letter from Richard J. Laufer, NRC, to Bryce L. Shriver, PPL Susquehanna, "Susquehanna Steam Electric Station, Unit I - Relief from American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code),Section XI, Appendix VIII, Supplement 11, Requirements and Code Cases N-504-2 and N-638 Requirements (TAC Nos. MC2450, MC2451 and MC2594)," Accession Number ML051220568, dated June 22, 2005.

3. Letter from L. Raghavan, NRC, to Mano K. Nazar, I&M, "Donald C. Cook Nuclear Plant, Unit I - Alternative to Repair Requirements of Section XI of the American Society of Mechanical Engineers Code (TAC No. MC06751)," Accession Number ML051720006, dated June 27, 2005.

4. Letter from Richard J. Laufer, NRC, to George Vanderheyden, Calvert Cliffs, "Calvert Cliffs Nuclear Power Plant, Unit No. 2 - Relief Request for Use Weld Overlay and Associated Alternative Inspection Techniques (TAC Nos. MC6219 and MC6220),"

Accession Number ML051930316, dated July 20, 2005.

5. Letter from Darrell J. Roberts, NRC, to David A. Christian Dominion Nuclear Connecticut, Inc., "Millstone Power Station, Unit No. 3 - Issuance of Relief from Code Requirements (TAC No. MC8609)," Accession Number ML053260012, dated January 20, 2006.

6. Southern California Edison's San Onofre Unit 2, verbal authorization given on March 23, 2006; and

7. First Energy's Davis Besse Unit 1, verbal authorization given on April 5, 2006.

9.0 REFERENCES

(1) ASME Code,Section XI, 1998 Edition through 2000 Addenda, JWA-4000.

(2) ASME Code,Section XI, 1998 Edition through 2000 Addenda, Mandatory Appendix VIII, Supplement 11.

(3) ASME Code Case N-504-2, Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping,Section XI, Division 1, March 12, 1997.

(4) ASME Code Section XI, through 2005 Addenda, Nonmandatory Appendix Q, Weld Overlay Repair of Class I , 2, and 3 Austenitic Stainless Steel Piping Weldments.

Page 8 of 24

Request No. 06-ON-004 Enclosure 1 (5) ASME Code Case N-638-1, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division I, February 13, 2003.

(6) ASME Code Case N-638-3, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division I, April 18, 2006 & accompanying white paper.

(7) Calvert Cliffs, Units 1 & 2 - ASME Section XI Relief Request to Use Weld Overlay & Associated Alternative Techniques, Accession Number ML060240110, dated January 18, 2006.

10.0 CONCLUSION

Duke concludes that the alternative repair approach described above presents an acceptable level of quality and safety to satisfy the requirements of 10 CFR 50.55a(a)(3)(i). The approach described in this relief request includes evaluation of available operating experience related to previously NRC approved applications of overlays to DMW.

Page 9 of 24

Request No. 06-ON-004 Enclosure 1 SA-508 CL.1 ALLOY 52M PZR SURGE A-336 CL FBM

'WELD OVERLAY NOZZLE FORGING SAFE END

+

CLADDING ALLOY 82/182 WELD/BULTTER Figure 1: Pressurizer Surge Nozzle Weld Overlay (Typical)

Page 10 of 24

Request No. 06-ON-004 Enclosure I A- 105 GR.2 HOT LEG SURGE NOZZLE FORGING A-376 Gr TP316 ATTACHED PIPING Figure 2: Hot Leg Surge Nozzle Weld Overlay (Typical)

Page 11 of 24

Request No. 06-ON-004 Enclosure 1 SA-508 CL.I SPRAY NOZZLE FORGING r TP316 PIPING CLADDING WELD/BUTTER SB-166 SAFE END Figure 3: Pressurizer Spray Nozzle Weld Overlay (Typical)

Page 12 of 24

Request No. 06-ON-004 Enclosure 1 SA-182 Cr F316 SA-508 CL.1 SAFETY/RELIEF NOZZLE FORGING CLADDING ALLOY 82/182 WELD/BUTTER Figure 4: Pressurizer Safety/Relief Nozzle Weld Overlay (Typical)

Page 13 of 24

Request No. 06-ON-004 Enclosure 1 ATTACHMENT 1 CONTENTS Table I Modifications to Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirements Table 2 Alternatives to Appendix VIII, Supplement 11 Table 3 Modifications to Code Case N-638-1 Page 14 of 24

Request No. 06-ON-004 Enclosure I Table 1 Modifications To Code Case N.504-2 and Corresponding Non-Mandatory Appendix Q Requirements Code Case N-504-2 Modification/Basis Modification. Code Case N-504-2 will be used for weld overlay repairs to the ferritic and nickel alloy base material as well as the austenitic stainless steel base material.

Reply: It is the opinion of the Committee that, in lieu of the requirements of Basis: Code Case N-504-2 is acceptedfor use along with Nonmandatory IWA-4120 in Editions and Addenda up to and including the 1989 Edition with Appendir Q in the current NRC Regulatory Guide 1.147 Rev. 14. For the weld the 1990 Addenda, in IWA-4170(b) in the 1989 Edition with the 1991 Addenda overlay of the identified welds at Oconee Units 1, 2 & 3 the base materialwill be up to and including the 1995 Edition, and in IWA-4410 in the 1995 Edition with ferriticmaterial with existing nickel alloy weld metal to which an austenitic the 1995 Addenda and later Editions and Addenda, defect in austenitic stainless stainless steel or Alloy 600 safe end is welded. Industry operationalexperience steel piping may be reduced to a flaw of acceptable size in accordance with IWB- has shown that PWSCC in Alloy 82/182 will blunt at the interface with stainless 3640 from the 1983 Edition with the Winter 1985 Addenda, or later Editions and steel base metal, ferritic base metal, or Alloy 52/52M/52MS weld metal. The Addenda, by deposition of weld reinforcement (weld overlay) on the outside 3600 structuralweld overlay will control growth in any PWSCC crack and surface of the pipe, provided the following requirements are met. [Essentially maintain weld integrity. The weld overlay will induce compressive stress in the same as Scope of Appendix Q]: weld, thus impeding growth of any reasonably shallow cracks. Furthermore,the overlay will be sized to meet all structuralrequirements independent of the existing weld.

Modification. In lieu of austenitic stainless steel filler material, the reinforcement weld metal will be a nickel alloy.

Basis: The weld metal used may be ERNiCrFe-7A (Alloy 52M, UNS N06054) or ERNiCrFe-7(Alloy 52 UNS N06052). This weld metal is assigned F43 by ASME per Code Case 2142-2. The requirementsofASME Section III, NB-2400 will be appliedto allfillermaterial.The chromium content ofAlloy 52M/MS is 28-31.5%, identical to that of Alloy 52. The main difference in Alloy 52 vs. Alloy (b) Reinforcement weld metal shall be low carbon (0.035% max.) austenitic 52M/MS is a higher Niobium content (0.5-1 %). The difference in chemical stainless steel applied 360r around the circumference of thepipe, and shall be composition between Alloy 52 and Alloy 52M/MS improves the weld-ability of deposited in accordance with a qualified welding procedure specification the materialand pins the grain boundariesthus preventing separationbetween identified in the Repair Program. [Same as Q-2000(a)] the grains and hot tearing (uring weld puddle solidification. These filler materials were selectedfor their improved resistanceto PWSCC. Alloys 52 and 52M/MS contain about 30% chromium that imparts excellent corrosion resistance.The existing Alloy 82/182 weld and the Alloy 52M/52MS overlay are nickel base and have ductile propertiesand toughness similarto austenitic stainless steel piping welds at pressurized water reactoroperating temperature.

These filler miaterialsare suitablefor welding over theferriticnozzle, nickel alloy weld or base material,and the aisteniticstainless steel safe end or pipe Page 15 of 24

Request No. 06-ON-004 Enclosure I Table 1 Modifications To Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirements Code Case N-504-2 Modification/Basis components.

(e) The weld reinforcement shall consist of a minimum of two weld layers Modification: Delta ferrite (FN) measurements will not be performed for weld having as-deposited delta ferrite content of at least 7.5 FN. The first layer of weld overlay repairs made of Alloy 52/52M152MS weld metal.

metal with delta ferrite content of least 7.5 FN shall constitute the first layer of Basis: Welds o f Al oy5/2522MS are metal.

the weld reinforcement design thickness. Alternatively, first layers of at least 5 ferrite dWle to tie high nickel composition (approximately 60% nickel).

FN may be acceptable based on evaluation. [Same as Q-2000(d)]

Modification: If a flaw or evidence of a flaw is observed, in lieu of hydrostatic testing, a system leakage test and an ultrasonic examination (UT) of the weld Pressure Testing overlay will be performed consistent with ASME IWA-4540(a)(2), as modified (h) The completed repair shall be pressure tested in accordance with IWA-5000. by Nonmandatory Appendix Q.

If the flaw penetrated the original pressure boundary prior to welding, or if any Basis: Application of IWA-4540(a)(2) for a system leakage test in lieu of a evidence of a flaw penetrating the pressure boundary is observed during the system hydrostatictest requiresperformance of NDE in accordance with the welding operation, a system hydrostatic test shall be performed in accordance methods and acceptance criteriaof the applicableSubsection of the 1992 Edition weling opera Iftionea systemhydrostaticboutest hall be t permen ed ordaned, aof ASME Section III. A SME Section III Subsection NB Article 5000for with IWA-5000. If the system pressure boundary has not been penetrated, a Examination does not addressthe structuralweld overlay type configuration.

system leakage, inservice, or functional test shall be performed in accordance The NDE requirements of NonnandatoryAppendix Q will be followed for the requiredNDE in lieu ofASME Section III. Code Case N-504-2 and NonmnandatoryAppendix Q provide appropriateexamination requirements including examination volume, acceptance criteria,and examinationmethods per Appendix VIII.

Page 16 of 24

Request No. 06-ON-004 Enclosure 1 Table 2 Alternatives to Appendix VIII, Supplement 11 Appendix VIII of Section XI cannot be used for NDE of a structural weld overlay repair. Relief is requested to use the PDI program implementation of Appendix VIII. A detailed comparison of Appendix VIII and PDI requirements is summarized below.

Relief is requested to allow closer spacing of flaws provided the flaws do not interfere with detection or discrimination of other discontinuities. The specimens used for qualification to the Tri-party (NRC/BWROG/EPRI) agreement have a flaw population density greater than allowed by current Code requirements. These samples have been used successfully for all previous qualifications under the Tri-party agreement program. To facilitate their use and provide continuity from the Tri-party agreement program to Supplement 11, the PDI program has merged the Tri-party test specimens into their structural weld overlay program.

SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDT PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING The Proposed Alternative to Supplement 11 Requirements WELDS 10 SPECIMEN REQUIREMENTS 1.1 General. The specimen set shall conform to the following requirements.

(b) The specimen set shall consist of at least three specimens having different nominal pipe diameters and overlay thicknesses. They shall include the minimum and maximum Alternative: (b) The specimen set shall include specimens with overlays not thicker nominal pipe diameters for which the examination procedure is applicable. Pipe than 0.1 inch more than the minimum thickness, nor thinner than 0.25 inch of the diameters within a range of 0.9 to 1.5 times a nominal diameter shall be considered maximum nominal overlay thickness for which the examination procedure is equivalent. If the procedure is applicable to pipe diameters of 24 inch or larger, the specimen set must include at least one specimen 24 inch or larger but need not include apicable.

Basis: To avoid confutsion, the overlay thickness tolerance contained in the last the maximum diameter. The specimen set must include at least one specimen with sentence was reworded and the phrase "and the remaindershall be alternativeflaws" overlay thickness within -0.1 inch to +0.25 inch of the maximum nominal overlay was added to the next to last sentence in paragraph1.1 (d) (1).

thickness for which the procedure is applicable.

(d) Flaw Conditions (1) Base metal flaws. All flaws must be cracks in or near the - butt weld heat-affected Alternative: (1) ... must be in or... intentional overlay fabrication flaws shall not zone, open to the inside surface, and extending at least 75% through the base metal interfere with ultrasonic detection or characterization of the base metal flaws.

Specimens containing intergranular stress corrosion cracking shall be used when wall. Flaws may extend 100% through the base metal and into the overlay material; in available. At least 70% of the flaws in the detection and sizing tests shall be cracks and this case, intentional overlay fabrication flaws shall not interfere with ultrasonic the remainder shall be alternative flaws. Alternative flaw mechanisms, if used, shall detection or characterization of the cracking. Specimens containing IGSCC shall be provide crack-like reflective characteristics and shall be limited by the following:

(a) The use of alternative flaws shall be limited to when the implantation of cracks

Request No. 06-ON-004 Enclosure 1 Table 2 Alternatives to Appendix VIII, Supplement I1 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING PDI PROGRAM:

WELDS The Proposed Alternative to Supplement 11 Requirements produces spurious reflectors that are uncharacteristic of actual flaws.

(b) Flaws shall be semi elliptical with a tip width of less than or equal to 0.002 inches.

Basis: This paragraphrequires that all base metalflaws be cracks. Implanting a crack requires excavation of the base materialon at least one side of the flaw. While this may be satisfactoryforferriticmaterials, it does not produce a useable axialflaw in atustenitic materials because the sound beam, which normally passes only through base material,must now travel through weld material on at least one side, producing an unrealistic flaw response. To resolve this issue, the PDIprogram revised this paragraphto allow use of alternativeflaw mechanisms under controlled conditions.

For example, alternativeflaws shall be limited to when implantation of cracks precludes obtaining an effective ultrasonicresponse,flaws shall be semi elliptical with a tip width of less than or equal to 0.002 inches, and at least 70% of the flaws in the detection and sizing test shall be cracks and the remaindershall be alternativeflaws.

To avoid confusion, the overlay thickness tolerancecontained in paragraph1.l(b) last sentence, was rewordedand the phrase "and the remaindershall be alternativeflaws" was added to the next to last sentence. Paragraph1.l(d)(l) includes the statement that intentional overlayfabricationflaws shall not interfere with ultrasonic detection or characterizationof the base mnetalflaws.

(e) Detection Snecimens Alternative: (1) At least 20% but less than 40% of the base metal flaws shall be oriented within +/-20° of the pipe axial direction. The remainder shall be oriented circumferentially. Flaws shall not be open to any surface to which the candidate has physical or visual access.

(1) At least 20% but less than 40% of the flaws shall be oriented within +/-20" of the pipe axial direction. The remainder shall be oriented circumferentially. Flaws shall not Basis: The requirementfor axially oriented overlay fabricationflaws was excluded be open to any surface to which the candidate has physical or visual access. The rules from the PDI Prograinas an improbable scenario. Weld overlays are typically applied of IWA-3300 shall be used to determine whether closely spaced flaws should be treated using automnated GTA W techniques with thefiller metal applied in a circutnferential as single or multiple flaws. direction. Because resultantfabrication induced discontinuitieswould also be expected to have major dinensionsoriented in the circutmferentialdirection axial overlay fabricationflaws are unrealistic. The requiremnentfor using IWA-3300 for proximity flaw evaluation was excluded; instead indications will be sized based on their individual merits.

-I (2) Specimens shall be divided into base and overlay grading units. Each specimen Alternative: (2) Specimens shall be divided into base metal and overlay fabrication shall contain one or both types of grading units. grading units. Each specimen shall contain one or both types of grading units. Flaws shall not interfere with ultrasonic detection or characterization of other flaws.

Page 18 of 24

Request No. 06-ON-004 Enclosure I Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING The Proposed Alternative to Supplement 11 Requirements WELDS Basis: Inclusion of "metal" and 'fabrication"provides clarification.Flaw identification is improved by ensuringflaws are not masked by otherflaws.

Alternative: (a)(1) A base metal grading unit includes the overlay material and the outer 25% of the original overlaid weld. The base metal grading unit shall extend circumferentially for at least 1 inch and shall start at the weld centerline and be wide enough in the axial direction to encompass one half of the original weld crown and a (a)(1) A base grading unit shall include at least 3 inch of the length of the overlaid minimum of 0.50" of the adjacent base material.

weld. The base grading unit includes the outer 25% of the overlaid weld and base metal Basis: The phrase "andbase metal on both sides," was inadvertently included in the on both sides. The base grading unit shall not include the inner 75% of the overlaid description of a base metal gradingunit, The PDI program intentionally excludes this weld and base metal overlay material, or base metal to-overlay interface. requirement because some of the qualification samples includeflaws on both sides of the weld. To avoid confusion several instancesof the term "cracks" or "cracking" were changed to the term "flaws" because of the use of alternativeFlaw mechanisms.

Modified to requirethat a base metal grading unit include at leastlinch of the length of the overlaid weld, ratherthan 3 inches.

(a)(2) When base metal cracking penetrates into the overlay material, the base grading Alternative: (a)(2) When base metal flaws penetrate into the overlay material, the base unit shall include the overlay metal within 1 inch of the crack location. This portion of metal grading unit shall not be used as part of any overlay fabrication grading unit.

Basis: Substituted terms provide clarificationand are consistent with Id(l) above. The the overlay material shall not be used as part of any overlay grading unit. PD! program adjustsfor this conservative changefor excluding this type grading tunit.

Alternative: (a)(3) Sufficient unflawed overlaid weld and base metal shall exist on all (a)(3) When a base grading unit is designed to be unflawed, at least 1 inch of unflawed sides of the grading unit to preclude interfering reflections from adjacent flaws.

overlaid weld and base metal shall exist on either side of the base grading unit. The Basis: Modified to require sufficient unflawed overlaid weld and base metal to exist on segment of weld length used in one base grading unit shall not be used in another base all sides of the grading unit to preclude interfering reflectionsfrom adjacentflaws, grading unit. Base grading units need not be uniformly spaced around the specimen. ratherthan the 1 inch requirement.

Alternative: (b)(1) An overlay fabrication grading unit shall include the overlay material and the base metal-to-overlay interface for a length of at least 1 inch (b)(1) An overlay grading unit shall include the overlay material and the base metal-to- Basis: The PDlprogram reduces the base metal-to-overlay interface to at least I inch overlay interface of at least 6 in2. The overlay grading unit shall be rectangular, with (in lieu of a minimum of 2 inches) and eliminatesthe mininmumt rectangulardimension.

minimum dimensions of 2 inch This criterion is necessary to allow use of existing examination specimens that were fabricatedin orderto meet NRC Generic Letter 88-01. This criterionmay be more challenging than the ASME Code because of the variabilityassociatedwith the shape I of the grading unit.

Page 19 of 24

Request No. 06-ON-004 Enclosure 1 Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING The Proposed Alternative to Supplement 11 Requirements WELDS Alternative: (b)(2) Overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 inch at both ends. Sufficient unflawed overlaid weld and base metal shall (b)(2) An overlay grading unit designed to be unflawed shall be surrounded by exist on both sides of the overlay fabrication grading unit to preclude interfering unflawed overlay material and unflawed base metal-to-overlay interface for at least I reflections from adjacent flaws. The specific area used in one overlay fabrication inch around its entire perimeter. The specific area used in one overlay grading unit grading unit shall not be used in another overlay fabrication grading unit. Overlay shall not be used in another overlay grading unit. Overlay grading units need not be fabrication grading units need not be spaced uniformly about the specimen.

spaced uniformly about the specimen. Basis: Paragraph1.1 (e)(2)(b)(2) states that overlay fabricationgrading units designed to be unflaiwed shall be separatedby unflawed overlay materialand unflalwed base metal-to-overlay interface for at least 1 inch at both ends, ratherthan around its entire perimeter.

Alternative:...base metal grading units, ten unflawed base metal grading units, five (b)(3) Detection sets shall be selected from Table VIII-S2-1. The minimum detection flawed overlay fabrication grading units, and ten unflawed overlay fabrication grading sample set is five flawed base grading units, ten unflawed base grading units, five units. For each type of grading unit, the set shall contain at least twice as many flawed overlay grading units, and ten unflawed overlay grading units. For each type of unflawed as flawed grading units. For initial procedure qualification, detection sets grading unit, the set shall contain at least twice as many unflawed as flawed grading shall include the equivalent of three personnel qualification sets. To qualify new values units. of essential variables, at least one personnel qualification set is required.

Basis: Clarifiedthe guidancefor initialprocedure qualificationsversuts qualifying new values of essential variables.

(f) Sizing Specimen Alternative: (1) The...least 40% of the flaws shall be open to the inside surface. Sizing (1) The minimum number of flaws shall be ten. At least 30% of the flaws shall be sets shall contain a distribution of flaw dimensions to assess sizing capabilities. For (1)vTherla mainatimumonumber offflawslshallw.

At least of the 30%

flawsrinitial shall be procedure qualification, sizing sets shall include the equivalent of three overlay fabrication flacs. At least 40% of the flaws shall be cracks open to the inside personnel qualification sets. To qualify new values of essential variables, at least one personnel qualification set is required.

Basis: Clarifiedthe guidancefor initial procedure qualificationsversus qualifying new values of essential variablesand is consistent with ld(l) above..

(3) Base metal cracking used for length sizing demonstrations shall be oriented Alternative: (3) Base metal flaws used.. circumferentially.

circumferenti ally. Basis: Clarified wording to be consistent with ld(l) above.

(4) Depth sizing specimen sets shall include at least two distinct locations where Alternative: (4) Depth sizing specimen sets shall include at least two distinct locations cracking in the base metal extends into the overlay material by at least 0.1 inch in the where a base metal flaw extends into the overlay material by at least 0.1 incli in the through-wall direction. through-wall direction.

Page 20 of 24

Request No. 06-ON-004 Enclosure 1 Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING The Proposed Alternative to Supplement 11 Requirements WELDS Basis: Clarifiedwording to be consistent with ld(l) above.

2.0 Conduct of Performance Demonstration The specimen inside surface and identification shall be concealed from the candidate. Alternative: The specimen ...prohibited. The overlay fabrication flaw test and the base All examinations shall be completed prior to grading the results and presenting the metal flaw test may be performed separately.

results to the candidate. Divulgence of particular specimen results or candidate viewing Basis: Clarified wording to describe process.

of unmasked specimens after the performance demonstration is prohibited.

2.1 Detection Test.

Flawed and unflawed grading units shall be randomly mixed. Although the boundaries of specific grading units shall not be revealed to the candidate, the candidate shall be Alternative: Flawed.. .(base metal or overlay fabrication).. .each specimen.

made aware of the type or types of grading units (base or overlay) that are present for Basis: Clarifiedwording similarto 1(e)2 above..

each specimen.

2.2 Length Sizing Test (d) For flaws in base grading units, the candidate shall estimate the length of that part Alternative: (d) For... base metal grading ... base metal wall thickness.

of the flaw that is in the outer 25% of the base wall thickness. Basis: Clarifiedwording for consistency.

2.3 Depth Sizing Test.

Alternative: (a) The depth sizing test may be conducted separately or in conjunction with the detection test.

(b) When the depth sizing test is conducted in conjunction with the detection test and For the depth sizing test, 80% of the flaws shall be sized at a specific location on the the detected flaws do not satisfy the requirements of 1.1(f), additional specimens shall surface of the specimen identified to the candidate. For the remaining flaws, the regions be provided to the candidate. The regions containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the of each specimen containing a flaw to be sized shall be identified to the candidate. The flaw in each region.

candidate shall determine the maximum depth of the flawv in each region. (c) For a separate depth sizing test, the regions of each specimen containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.

Basis: Clarified wording to better describe process.

3.0 ACCEPTANCE CRITERIA 3.1 Detection Acceptance Criteria Examination procedures, equipment, and personnel are Alternative: Examination procedures are qualified for detection when:

qualified for detection when the results of the performance demonstration satisfy the a. All flaws within the scope of the procedure are detected and the results of the acceptance criteria of Table VIII-S2-1 for both detection and false calls. The criteria performance demonstration satisfy the acceptance criteria of Table VIII-S2-1 for false shall be satisfied separately by the demonstration results for base grading units and for calls.

overlay grading units. b. At least one successful personnel demonstration has been performed meeting the acceptance criteria defined in (c).

Page 21 of 24

Request No. 06-ON-004 Enclosure 1 Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

PIPORM STRUCTURAL OVERLAIDSWRO WROUGHT AUSTENITIC PIPING T AThe Proposed Alternative to Supplement 11 Requirements WELDS__________________________

c. Examination equipment and personnel are qualified for detection when the results of the performance demonstration satisfy the acceptance criteria of Table VIII-S2-1 for both detection and false calls.

d. The criteria in (b) and (c) shall be satisfied separately by the demonstration results for base metal grading units and for overlay fabrication grading units.

Basis: Clarifiedwording to better describe the difference between procedure qualification and equipment and personnel qualifications.

3.2 Sizing Acceptance Criteria (a) The RMS error of the flaw length measurements, as compared to the true flaw Alternative: (a) The...base metal flaws is.. position.

lengths, is less than or equal to 0.75 inch. The length of base metal cracking is Basis: Clarified wording to be consistent with Id(I) above.

measured at the 75% through-base-metal position.

Alternative: This requirement is omitted.

Basis: The requirementfor reporting all extensions of cracking into the overlay is (b) All extensions of base metal cracking into the overlay material by at least 0.1 inch omittedfrom the PD! Programbecause it is redundant to the RMS calcudations are reported as being intrusions into the overlay material, performed in paragraph3.2(c) and its presence adds confusion and anibiguity to depth sizing as requiredby paragraph3.2(c). This also makes the weld overlayprogram consistent with the supplement 2 depth sizing criteria Page 22 of 24

Request No. 06-ON-004 Enclosure I Table 3 Modifications to Code Case N-638-1 Code Case N-638-1 Modification/Basis Modification: The maximum area of an individual weld based on the finished surface over the ferritic materialwill not exceed 500 square Weld Area inches, and the depth of the WOL shall not be greater than one-half of 1.0(a) The maximum area of an individual weld the ferritic base metal thickness based on the finished surface shall be 100 sq. inch, Basis: The maximum area of the WOL for the surge line nozzle will be and the depth of the weld shall not be greater than approximately 125 sq-inch over the ferritic material. Code Case N-638-one-half of the ferritic base metal thickness. 3 and the associatedwhite paperhave been approvedby the ASME Code Committees, andprovide technicaljustification for extending the area limitation to 500 sq. inch.

Examination (Referenced below in 4.0(b) para. 1.0(d) Prior to welding the area to be welded and a band around the area of at least 11/2 times the Modification: The required liquid penetrant examination of 4.0(b) will component thickness or 5 inch, whichever is less shall be at least be performed. In lieu of ultrasonic examination in accordance with 50°F.) Appendix I, the ultrasonic examination will be in accordance with N-504-2 and Appendix Q.

4.0(b) The final weld surface and a band around the area defined in Basis: For the applicationof the weld overlay repairaddressedin this para. 1.0 (d) shall be examined using a surface and ultrasonic methods request the appropriateexamination methodologies and volumes are when the completed weld has been at ambient temperature for at least provided in Code Case N-504-2 and NonmandatoryAppendix Q Code 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The ultrasonic examination shall be in accordance with Case N-638-1 applies to any type of welding where a temper bead Appendix 1.3 technique is to be employed and is not specifically written for a weld overlay repair. Code Case N-638-3 has eliminated the requirementto examine a band aroundthe area to be welded, and specifies required 3Refer to the 1989 Edition with the 1989 Addenda and later Editions post weld non-destructive examination of the welded region only.

and Addenda Page 23 of 24

Request No. 06-ON-004 Enclosure 1 Table 3 Modifications to Code Case N-638-1 Code Case N-638-1 Modification/Basis Modification: Preheat and interpass temperatures for the weld overlay will be measured using a contact pyrometer. Interpass temperature will be monitored for the first three layers at each repair location. The interpass temperature measurements will be taken every three to five passes. After the first three layers, interpass temperature measurements will be taken every six to ten passes for the subsequent 4.0(c) requires temperature monitoring by welded thermocouples per layers. The heat input from layers beyond the third layer will not have a metallurgical affect on the low alloy steel HAZ.

IWA-461 0(a)

Basis: The proposed technique is fasterand does not compromise collection of requireddata, so welded thermocouples are not planned for use to monitorinterpass temperatureduring welding. Code Case N-638-3 has clarifiedthis requirementand specifically allows use of pyrometer measurements to determine interpasstemperatures. As noted earlierin this document, the NRC has previously approved this tvwe of temoeraturedata collection Page 24 of 24