ML061990111

Third Ten-Year Inservice Inspection Interval Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques

ML061990111
Person / Time
Site:	San Onofre
Issue date:	07/14/2006
From:	Scherer A Southern California Edison Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML061990111 (27)

Text

SOUTHERN CALIFORNIA A. Edward Schcrer EDISONManager of Nuclear Regulatory Affairs An EDISON INTERNATIONAL I Company July 14, 2006 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Subject:

Docket Nos.50-361 and 50-362 Third Ten-Year Inservice Inspection (ISl) Interval Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques San Onofre Nuclear Generating Station, Units 2 and 3

Dear Sir or Madam:

Pursuant to 10 CFR 50.55a(a)(3)(i), Southern California Edison (SCE) requests approval to use alternatives to the requirements of the American Society of Mechanical Engineers (ASME) Code, Section Xl, 1995 Edition through 1996 Addenda, IWA-4000, for repair/replacement activities related to the performance of structural weld overlays at San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 for the third 10-year inservice inspection (ISI) interval.

During the SONGS Unit 2 Cycle 14 refueling outage SCE performed a structural weld overlay on 4 high safety significant (HSS) Class 1 reactor coolant system (RCS) pressurizer, dissimilar metal, nozzle to safe end welds. The work was performed in accordance with ISI-3-18, submitted to the NRC by letter dated February 22, 2006, and supplemented by letter dated March 17, 2006. SCE has also submitted ISI-3-24 to support plans for performing a structural weld overlay for the similar welds in Unit 3 during the upcoming Unit 3 Cycle 14 refueling outage.

SCE is planning to perform a structural weld overlay on the pressurizer surge line nozzle to safe end welds and the adjacent stainless steel welds in both Units 2 and 3 to reduce dependence on the Alloy 82/182 welds as a pressure boundary weld and to mitigate any potential primary water stress corrosion cracking in the future.

P.O. Box 128 San Clemente, CA 92672 4 0(47 949-368-7501 Fax 949-368-7575

Document Control Desk July 14, 2006 SONGS Units 2 and 3 are in their third 10-year ISI interval, which started on August 18, 2003 and is scheduled to end on August 17, 2013. The 1995 Edition through 1996 Addenda of Section XI applies to the ISI program, the RI-ISI program, the Repair/Replacement program activities, and the requirements associated with Appendix VIII, Performance Demonstration for Ultrasonic Examination Systems.

Relief request ISI-3-25, similar to ISI-3-18 and ISI-3-24, is enclosed with this letter. It contains criteria for the proposed structural weld overlay of the welds with ISI Designation Numbers 02-005-031, 02-016-001, 03-005-031, and 03-016-001. Three tables attached to the enclosed relief request provide alternatives and modifications to the ASME Code requirements and Code Cases N-504-2 and N-638-1 that SCE has determined will be necessary to perform this and provide an acceptable level of quality and safety.

Unlike the weld overlays performed for the pressurizer spray and safety nozzles (ISI 18 and ISI-3-24) the size of the surge line nozzle will require an increase in the surface area of the weld such that it will exceed the 100 square inch limitation specified in Code Case N-638-1. ISI-3-25 requests an allowance up to 300 square inches.

Similar relief requests have been previously approved for AmerGen Energy Company for its Three Mile Island Nuclear Station, Unit 1 on July 21, 2004, for Susquehanna Steam Electric Station, on Unit 1, June 22, 2005, for Indiana Michigan Power Company for Donald C. Cook Nuclear Plant, Unit 1 on June 27, 2005, for Constellation Energy's Calvert Cliffs Nuclear Power Plant, Unit 2 on July 20, 2005, for Dominion Nuclear Connecticut for Millstone Power Station Unit 3, on January 20, 2006, and for SONGS Unit 2 on March 23, 2006.

SCE is in the process of developing design drawings and performing analyses for the structural weld overlay of the Unit 2 and Unit 3 surge nozzle, per the requirements specified in ISI-3-25.

SCE requests approval of this relief request to support the return to service of SONGS Unit 3 from the Cycle 14 refueling outage. SCE currently anticipates that approval would be needed by December 6, 2006, but it could occur earlier. Should you have any questions, please contact Mr. Jack Rainsberry at (949) 368-7420 Sincerely,

Enclosure:

cc: B. S. Mallett, Regional Administrator, NRC Region IV N. Kalyanam, NRC Project Manager, San Onofre Units 2 and 3 C. C. Osterholtz, NRC Senior Resident Inspector, San Onofre Units 2 and 3

Southern California Edison (SCE)

San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 Docket Nos. 50-361 and 50-362 Enclosure Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques CONTENTS 1.0 REASON FOR THE REQUEST ............................................................. 2 2.0 CODE COMPONENTS FOR WHICH RELIEF IS REQUESTED .............. 2 3.0 CODE REQUIREMENTS FOR WHICH RELIEF IS REQUESTED .......... 3 4.0 PROPOSED ALTERNATIVES AND SUPPORTING INFORMATION ...... 3 5.0 DURATION OF THE PROPOSED RELIEF REQUEST ............................ 6 6.0 PR EC ED ENTS ......................................................................................... 7 7.0 REFERENC ES ......................................................................................... 8 8.0 C O NC LU S IO N ............................................................................................ 8 ATTACHMENT 1 Table 1: Modifications To Code Case N-504-2 and Corresponding Nonmandatory Appendix Q Requirements Table 2: Alternatives To Appendix VIII. Supplement 11 Table 3: Modification To Code Case N-638-1 ATTACHMENT 2 Chemical Analyses of Incremental Milling of Weldment ATTACHMENT 3 Structural Weld Overlay Sketch Page 1 of 8

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques ProposedAltemative In Accordance with 10 CFR 50.55a(a)(3)(i)

- Alternative ProvidesAcceptable Level of Quality and Safety -

1.0 REASON FOR THE REQUEST Currently, there are no comprehensive criteria for a licensee to apply a structural weld overlay repair to a dissimilar metal weld that is constructed from Alloy 82/182 weld material, which is susceptible to primary water stress corrosion cracking (PWSCC). Although the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 1995 Edition through 1996 Addenda, IWA-4000 (Reference 1), is used for the San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 Section XI repair/replacement program, it does not have the needed requirements for this type of repair. The latest Nuclear Regulatory Commission (NRC) approved ASME Code also does not have the needed requirements for this type of repair. Repair/replacement activities associated with a structural weld overlay repair of this type are required to address the materials, welding parameters, ALARA concerns, operational constraints, examination techniques, and procedure requirements. Thus, this is the reason for this relief request.

2.0 CODE COMPONENTS FOR WHICH RELIEF IS REQUESTED Group: High safety significant (HSS) Class 1 dissimilar metal piping welds with Alloy 82/182 weld metal are believed to be susceptible to PWSCC.

a) Name of Components:

1. Unit 2 Pressurizer S21201ME087 surge nozzle to safe end HSS dissimilar metal weld (ISI Designation Number 02-005-031) with Alloy 82/182 weld material subject to PWSCC.

2. The adjacent Unit 2 Pressurizer S21201 ME087 stainless steel weld (ISI Designation Number 02-016-001)

3. Unit 3 Pressurizer S31201ME087 surge nozzle to safe end HSS dissimilar metal weld (ISI Designation Number 03-005-031) with Alloy 82/182 weld material subject to PWSCC.

4. The adjacent Unit 3 Pressurizer S21201ME087 stainless steel weld (ISI Designation Number 03-016-001)

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques b) ASME Code Class:

These welds are all ASME Code Class I welds located within the reactor coolant pressure boundary.

c) System:

Reactor Coolant System (RCS) d.1) Code Category: d.2) Code Category:

Examination Category B-F, Examination Category B-J, "Risk-

"Risk-Informed Piping Informed Piping Examinations" Examinations" e.1) Code Item No. B5.40 e.2) Code Item No. B9.11 "Welds subject to PWSCC" (ISI "Welds subject to Thermal Designation Numbers 02-005- Fatigue" (ISI Designation 031 and 03-005-031) Numbers 02-016-001 and 03-016-001)

"Welds subject to Thermal Fatigue" (ISI Designation Numbers 02-005-031 and 03-005-031) 3.0 CODE REQUIREMENTS FOR WHICH RELIEF IS REQUESTED 1995 Edition through the 1996 Addenda of the ASME Code Section XI, (Reference 1), IWA-4610(a).

1995 Edition with the 1996 Addenda, of the ASME Code,Section XI, Appendix VIII, Supplement 11 (Reference 2).

Modification to the Nuclear Regulatory Commission (NRC) approved Code Case N-504-2 with the 2005 Addenda, Nonmandatory Appendix Q (Reference 3).

Code Case N-638-1 (Reference 4). , Tables 1, 2, and 3 provide details of relief requested from each of the above requirements.

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques 4.0 PROPOSED ALTERNATIVES AND SUPPORTING INFORMATION A structural weld overlay repair is proposed for the pressurizer S2(3)1201ME087 surge nozzles to safe end HSS dissimilar metal welds (ISI Designation Numbers 02-005-031 and 03-005-031) and the adjacent welds (ISI Designation Numbers 02-016-001 and 03-016-001). The material of the above two nozzles is ferritic steel (P3). The pipe safe ends are austenitic stainless steel (P8). The surge nozzles material is SA-508 Class 2 and the safe end material is SA-351 CF8M.

The existing weld filler material is Alloy 82/182 (F43 equivalent to P43). The pipe is stainless steel SA-376 Grade TP316. The overlay will be designed as a structural weld overlay in accordance with ASME Section XI Code Case N-504-2 and Nonmandatory Appendix Q (Reference 3). The temper bead welding technique will be implemented in accordance with ASME Section Xl Code Case N-638-1 (Reference 4) for that portion of the overlay applied over the ferritic base material for which the Construction Code requires post-weld heat treatment.

Temperature monitoring requirements contained within this Code Case will be performed using contact pyrometers in lieu of thermocouples required by IWA-4610(a) of the ASME Code, Section Xl 1995 Edition through 1996 Addenda (Reference 1).

The weld overlays will extend around the full circumference of the nozzle-to-safe end and safe end to piping welds, as illustrated in Figure 1. The latter weld is included due to the close proximity to the dissimilar metal weld. This structural weld overlay is sized to satisfy the ASME Section III requirements without crediting the existing pipe. See Attachment 2 for the chromium content information of the weld material being used and Attachment 3 for a sketch of the design of the two structural weld overlays associated with this relief request. This structural weld overlay (weld reinforcement) will completely cover the existing Alloy 82/182 weld metal and will extend over the ferritic and austenitic stainless steel material on each end of the weld. To avoid stress risers, the weld material is extended and tapered across the pipe and nozzle side. The end slope is tapered to be no steeper than 45 degrees to minimize stress concentration. Sufficient overlay length is provided to allow for adequate transfer of axial loads between the pipe and the weld overlay. Therefore, the length of the actual structural weld overlay exceeds the minimum length required by ASME Code Case N-504-2 and Section Xl Appendix Q for load redistribution and inspection purposes. The thickness of the overlay is determined by the general Section Xl requirement that no flaw of depth greater than 75% through-wall is acceptable, along with the consideration of applied loading. The length of the structural weld overlay must be sufficient for inspection of an area that is 1/2 inch beyond the required repair length and the outer 25% of the original wall thickness.

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques In summary, the combination of deposition of PWSCC resistant weld reinforcement on the outside surface of the dissimilar metal weld, with favorable axial and hoop residual compressive stress produced on the inside diameter due to weld shrinkage will bear acceptable assurance for long term crack mitigation.

In addition, inservice inspection is facilitated because of the enhanced ability to inspect the joint.

Tables 1, 2, and 3, when used with the ASME Code, Section Xl, 1995 Edition through 1996 Addenda, Article IWA-4000 (Reference 1), provide a comprehensive package of proposed detailed criteria with requirements, proposed alternatives, methodologies, modifications, and the bases for these differences, to support this relief request. This SONGS Unit 2 and Unit 3 structural weld overlay repair of a piping weld with Alloy 82/182 weld material will be performed as a repair/replacement activity in accordance with IWA-4000 of the 1995 Edition, through 1996 Addenda, of ASME Section Xl (Reference 1) with the exception of the requirements in IWA-4610(a). In lieu of the weld-attached thermocouple requirements and recording instruments in IWA-4610(a), contact pyrometers and manual recording of the in-process temperatures will be used at SONGS Units 2 and 3. These contact pyrometers will be calibrated in accordance with the measuring and test equipment program and will be capable of monitoring the in-process temperatures from 50'F, minimum preheat temperature to 350°F, maximum interpass temperature.

Additionally, the methodology of Code Case N-504-2 (Reference 3), as modified and shown in Table 1, will be used. The ultrasonic examination of the completed structural weld overlay will be accomplished in accordance with ASME Section Xl, 1995 Edition with the 1996 Addenda, Appendix VIII, Supplement 11 (Reference 2) with the alternatives used to comply with the Performance Demonstration Initiative (PDI) program as shown in Table 2.

The temper bead weld technique requirements in accordance with Code Case N-638-1 (Reference 4) will be applied to the ferritic nozzle base material with the modifications described in Table 3. Code Case N-638-1 is conditionally approved for use for austenitic stainless steel material in NRC Regulatory Guide 1.147, Revision 14, August 2005, Code Case N-638-1 specifies a limit of 100 square inches for a temper bead weld. This applies to the surge line nozzles (14-inch diameter). The intent of the code case is clarified to limit the area of an individual weld over the ferritic material. Electric Power Research Institute Technical Report 1003616 (reference 5) provides justification for a maximum area of 500 square inches. The surge line nozzle weld area can be assumed to not exceed 300 square inches.

Any applicable requirements not addressed by Tables 1, 2, and 3 will be met as described in Section XI, 1995 Edition through 1996 Addenda, IWA-4000 Page 5 of 8

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques (Reference 1); Appendix VIII, Supplement 11 (Reference 2); Code Case N-504-2 (Reference 3); and Code Case N-638-1 (Reference 4).

Code Case N-504-2 (Reference 3) is approved for use for austenitic stainless steel material in NRC Regulatory Guide 1.147, Revision 14, August 2005, provided it is used with Nonmandatory Appendix Q, of ASME Section XI, 2005 Addenda. Provided in Table 1 are SCE's proposed modifications for structural weld overlay repair of nickel based and ferritic materials due to the specific construction of the SONGS Units 2 and 3 dissimilar metal welds. Therefore, SCE intends to follow the methodology of Code Case N-504-2 (Reference 3),

except for the modifications identified in Table 1.

5.0 DURATION OF PROPOSED RELIEF REQUEST This request will be applied for the remainder of the current SONGS Units 2 and 3 third 10-year ISI interval that started on August 18, 2003. Once these structural weld overlays are installed they 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 (Reference 3). The structural weld overlays are also subject to the satisfactory examination requirements of Article Q-4000 for inservice inspection. Those requirements include adding any installed structural weld overlay repairs into the SONGS Units 2 and 3 ISI plan per Subarticle Q-4300 for at least one inservice examination to be completed within the next 2 refueling cycles.

6.0 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 Inservice Inspection (ISI) Interval (TAC.No. MC1201)," 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.

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques

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 Leslie N. 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.

7.0 REFERENCES

(1) 1995 Edition through 1996 Addenda, ASME Code,Section XI, IWA-4000.

(2) 1995 Edition, ASME Code,Section XI, with the 1996 Addenda, 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, including ASME Code Section XI, 2005 Addenda, Nonmandatory Appendix Q, Weld Overlay Repair of Class 1 , 2, and 3 Austenitic Stainless Steel Piping Weldments.

(4) ASME Code Case N-638-1, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique Section XI, Division 1, February 13, 2003.

(5) Electric Power Research Institute Technical Report 1003616, "Additional Evaluations to Extend Repair Limits for Pressure Vessels and Nozzles," March 2004.

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques

8.0 CONCLUSION

SCE has determined that the approach described in this relief request includes available operating experience (OE) related to previously approved NRC requirements that have been used to produce acceptable structural weld overlay repairs when applied to a dissimilar metal weld with Alloy 82/182 weld material.

The basis for this determination is the application of this same type of structural weld overlay repair at Three Mile Island, Donald C. Cook, Calvert Cliffs, and Millstone. Those structural weld overlay repairs were based on, and this relief request includes, the NRC approved ASME Code requirements and Code Cases. SCE believes that the use of this relief request for a structural weld overlay repair at SONGS Units 2 and 3 will result in an acceptable level of quality and safety that meets the requirements of 10 CFR 50.55a(a)(3)(i).

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Attachment I San Onofre Nuclear Generating Station, Units 2 and 3, Comprehensive Criteria For Structural Weld Overlay of Welds Contains Modifications and Alternatives for the Use Of Relief Request ISI-3-25 Tables 1, 2, and 3

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 1 Modifications To Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirements Code Case N-504-2 Modification/Basis Reply: It is the opinion of the Committee that, in lieu of the Modification. Code Case N-504-2 will be used for weld overlay requirements of IWA-4120 in Editions and Addenda up to and repairs to the ferritic (P3) and nickel alloy (F43/P43) base including the 1989 Edition with the 1990 Addenda, in IWA- material as well as the austenitic stainless steel (P8) base 4170(b) in the 1989 Edition with the 1991 Addenda up to and material.

including the 1995 Edition, and in IWA-441 0 in the 1995 Edition Basis: Code Case N-504-2 is accepted for use along with with the 1995 Addenda and later Editions and Addenda, defect Nonmandatory Appendix Q in the current NRC Regulatory in austenitic stainless steel piping may be reduced to a flaw of Guide 1.147 Rev. 14. For the weld overlay of the identified acceptable size in accordance with IWB-3640 from the 1983 welds at SONGS Units 2 and 3 the base material will be ferritic Edition with the Winter 1985 Addenda, or later Editions and material (P3) with existing nickel alloy weld metal (F431P43) to Addenda, by deposition of weld reinforcement (weld overlay) which an austenitic stainless steel (P8) safe end is welded.

on the outside surface of the pipe, provided the following Industry operational experience has shown that PWSCC in requirements are met. [Essentially same as Scope of Alloy 82/182 will blunt at the interface with stainless steel base Appendix Q]: metal, ferritic base metal, or Alloy 52/52M weld metal. SONGS Units 2 and 3 plan to apply a 3600 structural weld overlay to control growth in any PWSCC crack and maintain weld integrity.

The weld overlay will induce compressive stress in the weld, thus impeding growth of any reasonably shallow cracks.

Furthermore, the overlay will be sized to meet all structural requirements independent of the existing weld.

(b) Reinforcement weld metal shall be low carbon (0. 035% Modification. In lieu of austenitic stainless steel filler material, max.) austenitic stainless steel applied 3600 around the the reinforcement weld metal will be a nickel alloy.

circumference of the pipe, and shall be deposited in Basis: The weld metal used may be ERNiCrFe-7A (Alloy 52M, accordance with a qualified welding procedure specification UNS N06054) or ERNiCrFe-7 (Alloy 52 UNS N06052). This identified in the Repair Program. [Same as Q-2000(a)] weld metal is assigned F43 by ASME per Code Case 2142-2.

The requirements of ASME Section III, NB-2400 will be applied to all filler material. The chromium content of Alloy 52M is 28-3 1.5%, identical to that of Alloy 52. The main difference in Alloy 1 52 vs. Alloy 52M is a higher Niobium content (0.5- 1 %).The Page 1 of 2

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table I Modifications To Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirements difference in chemical composition between Alloy 52 and Alloy 52M improves the weldability of the material and pins the grain boundaries thus preventing separation between the grains and hot tearing during weld puddle solidification. These filler materials were selected for their improved resistance to PWSCC. Alloys 52 and 52M contain about 30% chromium that imparts excellent corrosion resistance. The existing Alloy 82/182 weld and the Alloy 52/52M overlay are nickel base and have ductile properties and toughness similar to austenitic stainless steel piping welds at pressurized water reactor operating temperature. These filler materials are suitable for welding over the ferritic nozzle or pipe Alloy 821182 weld and the austenitic stainless steel pipe or safe ends.

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

least 7.5 FN shall constitute the first layer of the weld Basis: Welds of Alloy52/52M are 100% austenitic and contain reinforcement design thickness. Alternatively, first layers of at no delta ferrite due to the high nickel composition least 5 FN may be acceptable based on evaluation. [Same as (approximately 60% nickel).

Q-2000(d)]

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 2 Alternatives to Appendix VIII, Supplement 11 Appendix VIII of Section Xl cannot be used for NDE of a structural weld overlay repair. Relief is requested to use the PD1 program implementation of Appendix VIII. A detailed comparison of Appendix VIII and PD1 requirements is summarized below.

Relief is requested to allow closer spacing of flaws provided they don't interfere with detection or discrimination. The specimens used to date 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 Tn-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 PDI PROGRAM:

FOR FULL STRUCTURAL OVERLAID WROUGHT The Proposed Alternative to Supplement 11 AUSTENITIC PIPING WELDS Requirements 1 0 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 Alternative: (b) The specimen set shall include specimens with having different nominal pipe diameters and overlay overlays not thicker than 0.1 in. more than the minimum thicknesses. They shall include the minimum and maximum thickness, nor thinner than 0.25 in. of the maximum nominal nominal pipe diameters for which the examination procedure is overlay thickness for which the examination procedure is applicable. Pipe diameters within a range of 0.9 to 1.5 times a applicable.

nominal diameter shall be considered equivalent Ifthe Basis: To avoid confusion, the overlay thickness tolerance procedure is applicable to pipe diameters of 24 in. or larger, the contained in the last sentence was reworded and the phrase specimen set must include at least one specimen 24 in. or "and the remainder shall be alternative flaws" was added to the larger but need not include the maximum diameter. The next to last sentence in paragraph 1.1 (d) (1).

specimen set must include at least one specimen with overlay thickness within -0.1 in. to +0.25 in.of the maximum nominal overlay thickness for which the procedure is applicable.

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Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 2 Alternatives to Appendix VIII, Supplement 11 (d) Flaw Conditions (1) Base metal flaws. All flaws must be cracks in or near the - Alternative: (1) ... must be in or... intentional overlay butt weld heat-affected zone, open to the inside surface, and fabrication flaws shall not interfere with ultrasonic detection or extending at least 75% through the base metal wall. Flaws may characterization of the base metal flaws. Specimens containing extend 100% through the base metal and into the overlay intergranular stress corrosion cracking shall be used when material; in this case, intentional overlay fabrication flaws shall available. At least 70% of the flaws in the detection and sizing not interfere with ultrasonic detection or characterization of the tests shall be cracks and the remainder shall be alternative cracking. Specimens containing IGSCC shall be used when flaws. Alternative flaw mechanisms, if used, shall provide crack-available. 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 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 paragraph requires that all base metal flaws be cracks. Implanting a crack requires excavation of the base material on at least one side of the flaw. While this may be satisfactory for ferritic materials, it does not produce a useable axial flaw in austenitic 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 PDI program revised this paragraph to allow use of alternative flaw mechanisms under controlled conditions. For example, alternative flaws shall be limited to when implantation of cracks precludes obtaining an effective ultrasonic response, 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 remainder shall be alternative flaws. To avoid confusion, the overlay thickness tolerance contained in paragraph 1.1(b) last sentence, was reworded and the phrase "and the remainder shall be Page 2 of 7

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 2 Alternatives to Appendix VIII, Supplement 11 alternative flaws" was added to the next to last sentence.

Paragraph 1.1 (d)(1) includes the statement that intentional overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the base metal flaws.

(e) Detection Specimens (1) At least 20% but less than 40% of the flaws shall be oriented Alternative: (1) At least 20% but less than 40% of the base within +/-200 of the pipe axial direction. The remainder shall be metal flaws shall be oriented within +!-200 of the pipe axial oriented circumferentially. Flaws shall not be open to any direction. The remainder shall be oriented circumferentially.

surface to which the candidate has physical or visual access. Flaws shall not be open to any surface to which the candidate The rules of IWA-3300 shall be used to determine whether has physical or visual access.

closely spaced flaws should be treated as single or multiple Basis: The requirement for axially oriented overlay fabrication flaws. flaws was excluded from the PDI Program as an improbable scenario. Weld overlays are typically applied using automated GTA W techniques with the filler metal applied in a circumferential direction. Because resultant fabrication induced discontinuities would also be expected to have major dimensions oriented in the circumferential direction axial overlay fabrication flaws are unrealistic. The requirement for using IWA-3300 for proximity flaw evaluation was excluded, instead indications will be sized based on their individual merits.

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

(a)(1) A base grading unit shall include at least 3 in. of the Alternative: (a)(1) A base metal grading unit includes the length of the overlaid weld. The base grading unit includes the overlay material and the outer 25% of the original overlaid outer 25% of the overlaid weld and base metal on both sides. weld. The base metal grading unit shall extend circumferentially The base grading unit shall not include the inner 75% of the for at least I in. and shall start at the weld centerline and be overlaid weld and base metal overlay material, or base metal wide enough in the axial direction to encompass one half of the to-overlay interface, original weld crown and a minimum of 0.50" of the adjacent Page 3 of 7

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 2 Alternatives to Appendix VIII, Supplement 11 base material.

Basis: The phrase "and base metal on both sides," was inadvertently included in the description of a base metal grading unit, The PDI program intentionally excludes this requirement because some of the qualification samples include flaws on both sides of the weld. To avoid confusion several instances of the term "cracks" or "cracking" were changed to the term "flaws" because of the use of alternative Flaw mechanisms. Modified to require that a base metal grading unit include at least1 in. of the length of the overlaid weld, rather than 3 inches.

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

material shall not be used as part of any overlay grading unit (a)(3) When a base grading unit is designed to be unflawed, at Alternative: (a)(3) Sufficient unflawed overlaid weld and base least I in. of unflawed overlaid weld and base metal shall exist metal shall exist on all sides of the grading unit to preclude on either side of the base grading unit. The segment of weld interfering reflections from adjacent flaws.

length used in one base grading unit shall not be used in Modified to require sufficient unflawed overlaid weld and base another base grading unit. Base grading units need not be metal to exist on all sides of the grading unit to preclude uniformly spaced around the specimen. interfering reflections from adjacent flaws, rather than the I inch requirement.

(b)(1) An overlay grading unit shall include the overlay material Alternative: (b)(1) An overlay fabrication grading unit shall and the base metal-to-overlay interface of at least 6 in2 . The include the overlay material and the base metal-to-overlay overlay grading unit shall be rectangular, with minimum interface for a length of at least I in.

dimensions of 2 in. Modified to require sufficient unflawed overlaid weld and base metal to exist on all sides of the grading unit to preclude interfering reflections from adjacent flaws, rather than the I inch requirement (b)(2) An overlay grading unit designed to be unflawed shall be Alternative: (b)(2) Overlay fabrication grading units designed surrounded by unflawed overlay material and unflawed base to be unflawed shall be separated by unflawed overlay material Page 4 of 7

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 2 Alternatives to Appendix VIII, Supplement 11 metal-to-overlay interface for at least I in. around its entire and unflawed base metal-to-overlay interface for at least I in.

perimeter. The specific area used in one overlay grading unit at both ends. Sufficient unflawed overlaid weld and base metal shall not be used in another overlay grading unit. Overlay shall exist on both sides of the overlay fabrication grading unit grading units need not be spaced uniformly about the to preclude interfering reflections from adjacent flaws. The specimen. specific area used in one overlay fabrication grading unit shall not be used in another overlay fabrication grading unit Overlay fabrication grading units need not be spaced uniformly about the specimen.

Basis: Paragraph 1.1 (e)(2)(b)(2) states that 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 I in. at both ends, rather than around its entire perimeter.

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

(f) Sizing Specimen (1) The minimum number of flaws shall be ten. At least 30% of Alternative: (1) The...least 40% of the flaws shall be open to the flaws shall be overlay fabrication flaws. At least 40% of the the inside surface. Sizing sets shall contain a distribution of flaws shall be cracks open to the inside surface. flaw dimensions to assess sizing capabilities. For initial procedure qualification, sizing sets shall include the equivalent of three personnel qualification sets. To qualify new values of essential variables, at least one personnel qualification set is required.

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

shall be oriented circumferentially. I Page 5 of 7

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 2 Alternatives to Appendix VIII, Supplement 11 (4) Depth sizing specimen sets shall include at least two distinct Alternative: (4) Depth sizing specimen sets shall include at locations where cracking in the base metal extends into the least two distinct locations where a base metal flaw extends overlay material by at least 0.1 in. in the through-wall direction, into the overlay material by at least 0.1 in. in the through-wall direction.

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

to the candidate. Divulgence of particular specimen results or candidate viewing of unmasked specimens after the performance demonstration is prohibited.

2.1 Detection Test.

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

revealed to the candidate, the candidate shall be made aware of the type or types of grading units (base or overlay) that are present for each specimen.

2.2 Length Sizing Test (d) For flaws in base grading units, the candidate shall estimate Alternative: (d) For... base metal grading... base metal wall the length of that part of the flaw that is in the outer 25% of the thickness.

base wall thickness.

2.3 Depth Sizing Test.

For the depth sizing test, 80% of the flaws shall be sized at a Alternative: (a) The depth sizing test may be conducted specific location on the surface of the specimen identified to the separately or in conjunction with the detection test.

candidate. For the remaining flaws, the regions of each (b) When the depth sizing test is conducted in conjunction with specimen containing a flaw to be sized shall be identified to the the detection test and the detected flaws do not satisfy the candidate. The candidate shall determine the maximum depth requirements of 1.1(f), additional specimens shall be provided of the flaw in each region. 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 flaw 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 I candidate. The candidate shall determine the maximum depth Page 6 of 7

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 2 Alternatives to Appendix VIII, Supplement 11 of the flaw in each region.

a a a nn . .~ .. a I 4.U AWAo- 1AMAZ4 LUlI I MI(IA 3.1 Detection Acceptance Criteria Examination procedures, equipment, and personnel are Alternative: Examination procedures are qualified for detection qualified for detection when the results of the performance when:

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

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

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 arading units.

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

compared to the true flaw lengths, is less than or equal to 0.75 inch. The length of base metal cracking is measured at the 75%

through-base-metal position.

(b) All extensions of base metal cracking into the overlay Alternative: This requirement is omitted.

material by at least 0.1 in. are reported as being intrusions into Basis: The requirement for reporting all extensions of cracking the overlay material, into the overlay is omitted from the PDI Program because it is redundant to the RMS calculations performed in paragraph 3.2(c) and its presence adds confusion and ambiguity to depth sizing as required by paragraph 3.2(c). This also makes the weld overlay program consistent with the supplement 2 depth I sizing criteria Page 7 of 7

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 3 Modification To Code Case N-638-1 Code Case N-638-1 Modification/Basis 1.0 (a) The maximum area of an individual weld based on the Modification: The maximum area of an individual weld based finished surface shall be 100 sq. in., and the depth of the weld on the finished surface over the ferritic material will not exceed shall not be greater than one-half of the ferritic base metal 300 square inches, and the depth of the WOL shall not be thickness. greater than one-half of the ferritic base metal thickness.

Basis: The maximum finished area of the WOL for the surge line nozzle will exceed 100 sq-in over the ferritic material. EPRI Technical Report 1003616 provides technical justification for extending the size of the temper bead repairs up to a finished area of 500 sq-in over the ferritic material. The area of the finished overlays will be substantially less than this.

The WOL will extend to the transition taper of the low alloy steel nozzle so that qualified UT of the required volume can be performed'. There have been a number of temper bead WOL repairs applied to safe-end to nozzle welds in the nuclear industry, and a WOL repair having a 300 sq. in. surface was recently approved for the Susquehanna Steam Electric Station and the D. C. Cook (Precedents 2 and 3).

Results of industry analyses and testing performed to date have indicated that there is no direct correlation of amount of surface area repaired when comparing residual stresses using temper bead welding. Residual stresses associated with larger area repairs (> 100 sq in) remain compressive at an acceptable level.

i (Referenced below in 4.0(b) para. 1.0(d) Prior to welding the Modification: In lieu of the required ultrasonic examination of area to be welded and a band around the area of at least 1112 4.0(b) only the required liquid penetrant examination will be times the component thickness or 5in., whichever is less shall performed. The ultrasonic examination will be in accordance be at least 50°F.) with N-504-2 and Appendix 0.

Basis: For the application of the weld overlay repair addressed 4.0(b) The final weld surface and a band around the area in this request it is not possible to perform a meaningful defined in para. 1.0 (d) shall be examined using a surface and ultrasonic examination of the required band of base material ultrasonic methods when the completed weld has been at because of the existing nozzle configurations. This Code Case 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 />. The ultrasonic applies to any type of welding where a temper bead technique is examination shall be in accordance with Appendix 1.3 to be employed and is not specifically written for a weld overlay Page 1 of 2

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques Table 3 Modification To Code Case N-638-1 repair. However, it is believed that for this type of repair that any major base material cracking would take place in the HAZ 3 Refer to the 1989 Edition with the 1989 Addenda and later directly below the weld overlay or in the underlying Inconel Editions and Addenda 82/182 weld deposit and not in the required band of material out beyond the overlay. Therefore, it is assumed that if this cracking were to occur it would be identified by the ultrasonic examination of the weld overlay and not performing the required base material ultrasonic examination should be considered acceptable.

4.0(c) requires temperature monitoring by welded Modification: Preheat and interpass temperatures for the weld thermocouples per IWA-4610(a) pad will be measured using a contact pyrometer. Interpass temperature will be monitored for the first three layers at each repair location. On the first 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 layers. The heat input from layers beyond the third layer will not have a metallurgical affect on the low alloy steel HAZ.

Basis: Due to the location of the repair and area radiation dose rate, the placement of welded thermocouples for monitoring weld interpass temperature is determined to be not beneficial based on dose savings. Therefore, welded thermocouples are not planned for use to monitor interpass temperature during welding.

Page 2 of 2

Relief Request ISI-3-25 Use of Structural Weld Overlay and Associated Alternative Repair Techniques ATTACHMENT 2 CHEMICAL ANALYSES OF INCREMENTAL MILLING OF WELDMENT SONGS UNITS 2 and 3

ATTACHMENT 2 CHEMICAL ANALYSES OF INCREMENTAL MILLING OF WELDMENT SONGS UNITS 2 AND 3 The data shown below are typical of several mockups that are representative of the weld overlays to be installed. These data are from an overlay on carbon steel base material and testing has confirmed that the chromium content of overlays on stainless steel base materials is similar. The data supports the current overlay design, which specifies a single sacrificial layer that is not credited in the structural analysis of the overlay.

Chromium Content (wt. %)

For Orbital Welding Utilizing Alloy 52M Alloy 52M 2n" Layer 1 Layer 15' Layer 0.035" wire by X-ray by X-ray by Electron Diffraction from CMTR Fluoroscope Fluoroscope Spctroscopy Element/ SFA 5.14 Near Quadrant ER NiCrFe- Near Surface Near Surface Near Base 7A Surface layer Metal Chromium 0- 28.8 26.3 27.3 27.4 27.5 Chromium 90 - 29.5 26.9 29.1 28.0 27.4 Chromium 180 - 29.1 26.6 28.0 27.5 27.5 Chromium 270 - 29.4 27.0 26.7 26.9 26.4 Avg. % Cr 29.3 29.2 26.7 27.8 27.5 27.2 NOTE: These data are representative of the alloy 52M structural weld overlay repair to be deposited on the SONGS Units 2 and 3 pressurizer surge nozzles.

Subsequent layers will have %Cr equal to or greater than the 2nd layer Page I of I

ATTACHMENT 3 Structural Weld Overlay Sketch Sketch Representative of both the Unit 2 and the Unit 3 Surge Nozzle Assembly:

- SURGE NOZZLE (SA508, CL2)

- BUTTERING (182)

SAFE END/PIPE WELD (SS)

.SURGE LINE PIPE (SA376, Gr TP316)

FIGURE 1 STRUCTURAL WELD OVERLAY REPAIR FOR SONGS UNIT 2&3 PRESSURIZER 12" SURGE NOZZLE