ML101410060

Request for Approval of Alternate (Relief Request) for Dissimilar Metal Weld Repairs (ISI-04-05)

ML101410060
Person / Time
Site:	Calvert Cliffs
Issue date:	05/18/2010
From:	John Stanley Calvert Cliffs, Constellation Energy Nuclear Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML101410060 (49)

Text

Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 CENG a joint venture of Constellation

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%0EnergyeD CALVERT CLIFFS NUCLEAR POWER PLANT May 18, 2010 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit Nos. 1 & 2; Docket Nos. 50-317 & 50-318 Request for Approval of Alternative (Relief Request) for Dissimilar Metal Weld Repairs (ISI-04-05)

REFERENCES:

(a) American Society of Mechanical Engineers Boiler and Pressure Vessel, Code,Section XI, 2004 Edition, Articles IWA-4410 and IWA-4611 (b) American Society of Mechanical Engineers Boiler and Pressure Vessel, Code,Section XI, 2001 Edition, Appendix VIII, Supplement 11 As part of Calvert Cliffs Nuclear Power Plant's Fourth Ten Year Inservice Inspection Program Plan, we will be conducting weld examinations of dissimilar metal welds throughout the plan period. As a contingency, in case unacceptable flaw indications are found during any of these examinations, we are submitting [Attachment (1)] a relief request allowing the use of a full structural weld overlay as an alternative to Reference (a). The relief request is based on American Society of Mechanical Engineers Code Case N-740-2 as modified and supplemented in Attachment (1). In addition, we request an alternative, to perform the associated ultrasonic examinations in accordance with Reference (b) except as modified by the Performance Demonstration Initiative for full structural weld overlays installed as an alternative to Reference (a).

This relief request is submitted under the provision of 10 CFR 50.55a(a)(3)(i) as an alternative that provides an acceptable level of quality and safety.

We request the Nuclear Regulatory Commission complete the review of this relief request by February 28, 2011, in order to support the possible need fdr these repair methods as a result of weld examinations scheduled for Unit 2 spring 2011 refueling outage.

Document Control Desk May 18, 2010 Page 2 Should you have questions regarding this matter, please contact Mr. Douglas E. Lauver at (410) 495-5219.

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- Services JJS/KLG/bjd

Attachment:

(1) Relief Request to Use Alternative Techniques for Repair and Examination of Unacceptable Indications in Welded Nozzles (ISI-04-05)

Enclosures:

(1) Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

(2) Proposed Ambient Temperature Temperbead Technique (3) Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure I for Full Structural Weld Overlays (4) Technical Basis for Alternatives to ASME Code Case N-638-1, Ambient Temperature Temperbead Welding (5) Comparison of ASME Section XI Appendix VIII.,

Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay cc: D. V. Pickett, NRC Resident Inspector, NRC S. J. Collins, NRC S. Gray, DNR

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

Calvert Cliffs Nuclear Power Plant, LLC May 18, 2010

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

I. COMPONENTS FOR WHICH RELIEFIS REQUESTED Class I dissimilar metal welds (DMWs) with unacceptable indications attributed to primary water stress corrosion cracking (PWSCC) in existing.Alloy 82/182 welds. These welds may include:

!,,UNIT 1 DM ýWLD POPULATION D-Weld WedesignBator/D-.'

. .Base Material. Location r Stailness Steel Size DMWldDsinto/D Material. '_-WeldIlD 102300/30-RC-1 1A-W7 82/182 A516-70/A351-CF8M 1 A RCP Inlet 30-RC-1 1A-W8 30" Elbow to Safe End 102450/30-RC-11A-WI0 82/182 A516-70/A351-CF8M 11 A RCP Outlet 30-RC-1 1A-W9 30" Pipe to Safe End 104550/30-RC-1 IB-W7 82/182 A516-70/A351-CF8M 1 B RCP Inlet 30-RC-1 1B-W8 30" Elbow to Safe End 104700/30-RC-11B-W10 82/182 A516-70/A351-CF8M lIB RCP Outlet 30-RC-11B-W9 30" Pipe to Safe End 107450/30-RC-12A-W7 82/182 A516-70/A351-CF8M 12A RCP Inlet 30-RC-12A-W8 30" Elbow to Safe End 107600/30-RC-12A-W1O 82/182 A516-70/A351-CF8M 12A RCP Outlet 30-RC-12A-W9 30" Pipe to Safe End 109600/30-RC-12B-W7 82/182 A516-70/A351-CF8M 12B RCP Inlet 30-RC-12B-W8 30" Elbow to Safe End 109750/30-RC-12B-W1O 82/182 A516-70/A351-CF8M 12B RCP Outlet 30-RC-12B-W9 30" Pipe to Safe End 111100/12-PSL-W-13 82/182 A105-Gr II/A351-CF8M PZR Surge @ RCS Hot Leg 12-PSL-Wl2 12" Nozzle to Safe End 114350/12-SI-10009-W16 82/182 Al182-F-I/A351-CF8M Safety Injection to 1 A Cold Leg 12-SI-1009-WI 5 12" Nozzle to Safe End 11 5200/12-SI-1010-W14 82/182 A182-F-I/A351-CF8M Safety Injection to 1 B Cold Leg 12-SI-1010-W13 12" Nozzle to Safe End 116000/12-SI-1011 -W13 82/182 A182-F-I/A351-CF8M Safety Injection to 12A Cold Leg 12-SI-1011-W12 12" Nozzle to Safe End 1

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

. UNIT 1 DMAWELD POPULATION .

DM.Weld

,i6,_ Designator/ID, 0/- SI-,_0i

. Dge Welda .ýll Base Material, 2;, "Material Loat Wl DNozzle. Size:

I Stils 1)Steel 116750/12-SI-I012-W13 82/182 A182-F-I/A351-CF8M Safety Injection to 12B Cold Leg 12-SI-1012-W12 12" Nozzle to Safe End /

118550/3-PS-1001-WI 82/182 A105-Gr II/A-i 82 TP 316 PZR Spray from 1 A Cold Leg 3-PS-1001-W2 3" Nozzle to Safe End 120350/3-PS-1002-Wi 82/182 A105-Gr II/A-182 TP 316 PZR Spray from 1 B Cold Leg 3-PS-1002-W2 3" Nozzle to Safe End 123100/4-SR-1005-Wi 82/182 SA508-C12/SA- 182-F316 PZR Relief 4-SR-1005-W2 4" Nozzle to Safe End 123450/4-SR-1006-Wi 82/182 SA508-C12/SA- 182-F316 PZR Relief 4-SR- 1006-W2 4" Nozzle to Safe End 125050/2-LD-1004-WI 82/182 A105-Gr II/A-182-TP 316 12A Cold Leg Letdown/Drain 2-LD-1004-W2 2" Nozzle to Safe End 128900/2-CV-1004-W19 82/182 A105-Gr II/A-182-TP 316 12B Cold Leg Charging Inlet 2-CV-1004-W18 2" I Nozzle to Safe End 130450/2-CV-1005-W29 82/182 A105-Gr II/A-182-TP 316 11 A Cold Leg Charging Inlet 2-CV-1005-W28 2" Nozzle to Safe End 131200/2-DR-1003-WI 82/182 A105-Gr II/A-i 82-TP 316 11 A Cold Leg Loop Drain 2-DR-1003-WIA 2" Nozzle to Safe End 131500/2-DR-1004-WI 82/182 A105-Gr II/A-i 82-TP 316 11B Cold Leg Loop Drain 2-DR-1004-W1A 2" Nozzle to Safe End 132150/2-DR-1006-WI 82/182 A105-Gr II/A-182-TP 316 12B Cold Leg Loop Drain 2-DR-1006-WIA 2" I Nozzle to Safe End 2

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

-UNIT 2,DM WELDP PPULATION'.

D4M Weld,

~DM Wed BsMaea Dsigato/IDLoctioih)Noi~zle .. Stinless SteelI Size; M6Material a e 109280/30-RC-21A-W7 82/182 A516-70/A351-CF8M 21A RCP Inlet 30-RC-21A-W8 30" Elbow to Safe End 109310/30-RC-21A-Wi0 82/182 A516-70/A351-CF8M 21 A RCP Outlet 30-RC-21A-W9 30" Pipe to Safe End 110280/30-RC-21B-W7 82/182 A516-70/A351-CF8M 21B RCP Inlet 30-RC-21B-W8 30" Elbow to Safe End 110310/30-RC-21B-W10 82/182 A516-70/A351-CF8M 21B RCP Outlet 30-RC-21B-W9 30" Pipe to Safe End 111280/30-RC-22A-W7 82/182 A516-70/A351-CF8M 22A RCP Inlet 30-RC-22A-W8 30" Elbow to Safe End 111310/30-RC-22A-W1O 82/182 A516-70/A351-CF8M 22A RCP Outlet 30-RC-22A-W9 30" Pipe to Safe End 112280/30-RC-22B-W7 82/182 A516-70/A351-CF8M 22B RCP Inlet 30-RC-22B-W8 30" Elbow to Safe End 112310/30-RC-22B-W-10 82/182 A516-70/A351-CF8M 22B RCP Outlet 30-RC-22B-W9 30" Pipe to Safe End 113130/12-PSL-W-13 82/182 A105-Gr II/A351-CF8M PZR Surge @ RCS Hot Leg 12-PSL-W12 12" Nozzle to Safe End 115140/12-SI-2009-W15 82/182 A182-F-I/A351-CF8M Safety Injection to 21A Cold Leg 12-SI-2009-W15 12" Nozzle to Safe End 116190/12-SI-2010-W13 82/182 A182-F-1/A351-CF8M Safety Injection to 21B Cold Leg 12-SI-2010-W12 12" Nozzle to Safe End 117120/12-SI-201 l-W13 82/182 A182-F-1/A351-CF8M Safety Injection to 22A Cold Leg 12-SI-201 1-W12 12" Nozzle to Safe End 118120/12-SI-2012-W13 82/182 A182-F-l/A351-CF8M Safety Injection to 22B Cold Leg 12-SI-2012-W12 12" Nozzle to Safe End 137010/3-PS-2001-W1 82/182 A105-Gr II/A-182 TP 316 PZR Spray from 21A Cold Leg 3-PS-2002-W2 3" Nozzle to Safe End I II 3

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

UNIT 2 11DM WELD POPULATION

, oei. Ij W el .... a. e'] -,S..

DMWeldDesignator/ el Bcation StainlessSteel Nozz e Size M__eld,_siMaetar/-Weld .D 138010/3-PS-2002-W1 82/182 A105-Gr IIA-182 TP 316 PZR Spray from 21B Cold Leg 3-PS-2002-W2 3" Nozzle to Safe End 141000/4-SR-2005-W1 82/182 SA508-C12/SA-1 82-F316 PZR Relief 4-SR-2005-W2 4" Nozzle to Safe End 142000/4-SR-2006-W1 82/182 SA508-C12/SA-182-F316 PZR Relief 4-SR-2006-W2 4" Nozzle to Safe End 156530/2-CV-2021-W34 82/182 A105-Gr IIA-I 82-TP 316 22B Cold Leg Charging Inlet 2-CV-2021-W33 2" Nozzle to Safe End 152440/2-CV-2005-W30 82/182 A105-Gr II/A-182-TP 316 21A Cold Leg Charging Inlet 2-CV-2005-W29 2" Nozzle to Safe End 157010/2-DR-2003-W1 82/182 A105-Gr II/A-182-TP 316 21A Cold Leg Loop Drain 2-DR-2003-W2 2" Nozzle to Safe End 158010/2-DR-2004-W1 82/182 A105-Gr II/A-182-TP 316 21B Cold Leg Loop Drain 2-DR-2004-W2 2" Nozzle to Safe End 160010/2-DR-2006-W1 82/182 A105-Gr II/A-182-TP 316 22B Cold Leg Loop Drain 2-DR-2006-W2 2" Nozzle to Safe End 4

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

II. APPLICABLE CODE EDITION Calvert Cliffs Nuclear Power Plant (Calvert Cliffs) is currently in the fourth 10-year Inservice Inspection (ISI) interval (Reference 1). The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) of record for the current 10-year ISI interval isSection XI, 2004 Edition, No Addenda (Reference 2). This is also the Edition used for the Repair/Replacement Program.

II. APPLICABLE CODE REQUIREMENT American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, 2004 Edition, Articles IWA-44 10 and IWA-4611.

American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, 2001 Edition, Appendix VIII, Supplement 10, "Qualification Requirements for Dissimilar Metal Piping Welds," and Supplement 2, "Qualification Requirements for Wrought Austenitic Piping Welds."

IV. REASON FOR PROPOSEDALTERNATIVE Primary water stress corrosion cracking of Alloy 600 components and welds exposed to pressurized water reactor primary coolant has become a growing concern in the nuclear industry over the past decade. In particular, DMWs made with nickel Alloy 82 and 182 weld metal exposed to elevated operating temperatures, such as hot and cold leg DMWs, are believed to pose a heightened propensity to PWSCC.

Due to this concern, Calvert Cliffs is proposing full structural weld overlays (FSWOL) for the DMWs identified above, for potential implementation during the upcoming outages, as the most appropriate course of action to ensure Reactor Coolant System (RCS) pressure boundary integrity and improve future inspectability. The FSWOL can be either a mitigative or a repair weld overlay as defined in Enclosure 1.

The weld overlays are designed to provide a replacement structural boundary to the existing DMW and will extend around the full circumference of the existing nozzle Alloy 82/182 weld, overlapping the neighboring sections of carbon steel piping and stainless steel safe end. Due to the.proximity of the adjacent similar metal piping welds, the overlays will extend over the adjacent stainless steel safe end-to-nozzle welds, as necessary to provide sufficient overlay length for inspectability and residual stress improvement.

Structural weld overlays have been used for several years on piping of both boiling water reactors (BWRs) and pressurized water reactors to arrest the growth of existing flaws while establishing a new structural pressure boundary. Currently, there are no generically accepted Code-approved criteria for a licensee to apply a FSWOL to DMWs constructed of Alloy 82/182 weld material. Although Calvert Cliffs performs repair/replacement activities in accordance with the 2004 Edition of ASME Section XI, this edition of ASME Section XI does not include requirements for the application of weld overlays. For that matter, FSWOL requirements for nickel alloy welds are not presently included in any Edition/Addenda of ASME Section XI (including Code Cases) approved by the Nuclear Regulatory Commission (NRC).

Nozzle-to-safe end weld overlays have .been applied as repairs to other plants in accordance with ASME Code Cases N-504-2 and N-638-1. Previously Calvert Cliffs received a Safety Evaluation from the NRC to allow this alternative (Reference 3). Similar to the previous application, applying these code cases to nozzle DMWs requires a series of relief requests since Code Case N-504 was written specifically for stainless steel pipe-to-pipe welds and Code Case N-638-1 contains some restrictions and requirements that are not applicable to weld overlays. Code Case N-504 (and its later versions) has been updated to 5

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

Code Case N-504-3 and this code case has been approved by the NRC in Regulatory Guide 1.147, Revision 15. Code Case N-638-1 has also received regulatory approval in Regulatory Guide 1.147, Revision 15. Code Case N-740-2 has been approved by the ASME Code Committee to specifically address weld overlays on DMWs that involve nickel alloy welds. Although, Code Case N-740-2 has not yet been accepted by the NRC in Regulatory Guide 1.147, it builds on the previously NRC approved relief based on modification of Code Case N-504-2 and Code Case N-638-1 by combining the two Code Cases and modifications into a single Code Case. Therefore, Calvert Cliffs proposes alternatives to ASME Section XI, IWA-4410 and IWA-4611 based on Code Case N-740-2 as discussed in Enclosures 1 and 2.

Required ultrasonic examinations of any proposed FSWOLs are governed by the requirements contained in ASME Code,Section XI, Appendix VIII, Supplement 11. Calvert Cliffs proposes alternatives to Supplement 11 requirements as contained in Electric Power Research Institute (EPRI) Performance Demonstration Initiative (PDI). The proposed alternatives are detailed in Enclosure 5.

V. PROPOSEDALTERNATIVE Pursuant to 10 CFR 50.55a(a)(3)(i), Calvert Cliffs proposes the following as alternatives to the Code requirements specified in Section III above. The proposed alternatives, are applicable to the DMWs and adjacent stainless steel welds identified in Section I above.

A. Install FSWOLs in accordance with the proposed alternatives specified in Enclosures 1 and 2.

These alternatives are based on the methodology of ASME Section XI Code Case N-740-2 for a FSWOL. Materials Reliability Program (MRP)-139, Revision 1 (Reference 4) and MRP-169, Revision I (Reference 5) provide additional support to this code case, as identified in this request for alternative.

" Enclosure I specifies an alternative applicable to the design, fabrication, examination, pressure testing, and ISI of FSWOLs.

" Enclosure 2 specifies an alternative applicable to ambient temperature temperbead welding.

The Enclosure 2 alternative will be applied to the welds as an alternative to the post-weld heat treatment requirements of ASME Section III, and the temperbead requirements of ASME Section XI.

B. Perform ultrasonic examinations of the proposed FSWOLs in accordance with Appendix VIII, Supplement 11 of the 2001 Edition of ASME Section XI (Reference 6) except as modified by PDI.

The proposed PDI alternatives to Appendix VIII, Supplement 11 are specified in Enclosure 5 and comply with 10 CFR 50.55a. Existing PDI protocol for mockups and the qualification of the ultrasonic procedures for field use has not changed from previously approved requirements for FSWOLs contained in Reference 3.

VI. BASIS FOR PROPOSEDALTERNATIVE I

A. Proposed Alternative for Structural Weld Overlays If unacceptable flaw indications are identified, Calvert Cliffs intends to install FSWOLs to the DMWs (Alloy 82/182) identified in Section I above, in accordance with proposed alternative of Enclosure 1. A tabular comparison of the proposed alternative of Enclosure 1 with Code Case N-504-3 and Appendix Q of ASME Section XI has been performed and is provided in Enclosure 3.

6

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

This proposed alternative provides an acceptable methodology for preventing potential failures due to PWSCC based on the use of filler metals that are resistant to PWSCC (e.g., Alloy 52M),

procedures that create compressive residual stress profiles in the original weld, and post-overlay preservice and ISI requirements that ensure structural integrity for the life of the plant. The proposed weld overlays will also meet the applicable stress limits from ASME Section III. Crack growth evaluations for PWSCC and fatigue of any conservatively postulated flaws will demonstrate that structural integrity will be maintained.

I1. Full Structural Weld Overlay Design and Verification The fundamental design basis for FSWOLs is to maintain the original design margins with no credit taken for the underlying PWSCC-susceptible weldments. The assumed design basis flaw for the purpose of structural sizing the weld overlays is 3600 circumferential flaw that is 100% through the original wall thickness of the DMWs.

The following is a list of the specific analyses and verifications to be performed in the event a FSWOL will need to be installed in accordance with the requirements of this relief request.

" Nozzle-specific stress analyses will be performed to establish a residual stress profile in each nozzle. Severe internal diameter weld repairs will be assumed in these analyses that effectively bound any actual weld repairs that may have occurred in the nozzles. The analyses will then simulate application of the weld overlays to determine the final residual stress profiles. Post-weld overlay residual stresses at normal operating conditions will be shown to result in beneficial compressive stresses on the inner portion of the components, providing a condition that results in retarding or arresting crack growth and minimizing new crack initiation due to PWSCC.

" Fracture mechanics analyses will also be performed to predict crack growth for postulated flaws. Crack growth due to PWSCC and fatigue will be analyzed for the original DMW. The crack growth analyses will consider all design loads and transients, plus the post-weld overlay and through-wall residual stress distributions. It will demonstrate that the postulated cracks will not grow beyond the design basis for the weld overlays.

" The analyses will demonstrate that applying the weld overlays does not impact the conclusions of the existing nozzle stress reports. The ASME Code,Section III stress and fatigue criteria will be met for regions of the overlays remote from assumed cracks.

" 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 supports and restraints will be checked after the overlay repair, and will be adjusted within the design ranges as required.

" 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.

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

7

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

2. Suitability of Proposed Ambient Temperature Temperbead Technique An ambient temperature temperbead welding technique will be used when welding on the ferritic base materials of the nozzles in lieu of the post-weld heat treatment requirements of ASME Section III. Research by the EPRI and other organizations on the use of an ambient temperature temperbead process using the machine gas tungsten arc welding (GTAW) process is documented in EPRI Report GC- 111050 (Reference 7). According to the EPRI report, repair welds performed with an ambient temperature temperbead procedure utilizing the machine GTAW welding process exhibit mechanical properties equivalent to or better than those of the surrounding base material. Laboratory testing, analysis, successful procedure qualifications, and successful repairs have all demonstrated the effectiveness of this process.

The effects of the ambient temperature temperbead welding process of Enclosure 2 on mechanical properties of welds, hydrogen cracking, cold restraint cracking, and extent of overlay coverage of ferritic base metal are addressed in the following paragraphs:

Mechanical Properties The principal reasons to preheat a component prior to repair welding is to minimize the potential for cold cracking. The two cold cracking mechanisms are hydrogen cracking and restraint cracking. Both of these mechanisms occur at ambient temperature. Preheating slows down the cooling rate resulting in a ductile, less brittle microstructure thereby lowering susceptibility to cold cracking. Preheat also increases the diffusion rate of monatomic hydrogen that may have been trapped in the weld during solidification.

As an alternative to preheat, the ambient temperature temperbead welding process utilizes the tempering action of the welding procedure to produce tough and ductile microstructures.

Because precision bead placement and heat input control are utilized in the machine GTAW process, effective tempering of weld heat affected zones (HAZ) is possible without applying preheat. According to Section 2-1 of EPRI Report GC-11050 (Reference 7), "the temperbead process is carefully designed and controlled such that successive weld beads supply the appropriate quantity of heat to the untempered HAZ such that the desired degree of carbide precipitation (tempering) is achieved. The resulting microstructure is very tough and ductile."

The IWA-4600 temperbead process also includes a post-weld soak requirement. Performed at 450'F - 550'F for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> (P-No. 1 base materials), this post-weld soak assists diffusion of any remaining hydrogen from the repair weld. As such, the post-weld soak is a hydrogen bake-out and not a post-weld heat treatment as defined by the ASME Code. At 450'F -

550'F, the post-weld soak does not stress relieve, temper, or alter the mechanical properties of the weldment in any manner.

The alternative in Enclosure 2 establishes detailed welding procedure qualification requirements for base materials, filler metals, restraint, impact properties, and other procedure variables. The qualification requirements contained in Enclosure 2 provide assurance that the mechanical properties of repair welds will be equivalent to or superior to those of the surrounding base material.

8

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

Hydrogen Cracking Hydrogen cracking is a form of cold cracking. It is produced by the action of internal tensile stresses acting on low toughness HAZs. The internal stresses are produced from localized build-ups of monatomic hydrogen. Monatomic hydrogen forms when moisture or hydrocarbons interact with the welding arc and molten weld pool. The monatomic hydrogen can be entrapped during weld solidification and tends to migrate to transformation boundaries or other microstructure defect locations. As concentrations build, the monatomic hydrogen will recombine to form molecular hydrogen, thus generating localized internal stresses at these internal defect locations. If these stresses exceed the fracture toughness of the material, hydrogen-induced cracking will occur. This form of cracking requires the presence of hydrogen and low toughness materials. It is manifested by intergranular cracking of susceptible materials and normally occurs within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of welding.

IWA-4600 establishes elevated preheat and post-weld soak requirements. The elevated preheat temperature of 300'F increases the diffusion rate of hydrogen from the weld. The post-weld soak at 450'F was also established to bake-out or facilitate diffusion of any remaining hydrogen from the weldment. However, while hydrogen cracking is a concern for shielded metal arc welding, which uses flux covered electrodes, the potential for hydrogen cracking is significantly reduced when using the machine GTAW welding process.

The machine GTAW welding process is inherently free of hydrogen. Unlike the filler used in the shielded metal arc welding process, GTAW welding filler metals do not rely on flux coverings, which may be susceptible to moisture absorption from the environment.

Conversely, the GTAW process utilizes dry inert shielding gases that cover the molten weld pool from oxidizing atmospheres. Any moisture on the surface of the component being welded will be vaporized ahead of the welding torch. The vapor is prevented from being mixed with the molten weld pool by the inert shielding gas that blows the vapor away before it can be mixed. Furthermore, modern filler metal manufacturers produce wires having very low residual hydrogen. This is important because filler metals and base materials are the most realistic sources of hydrogen for automatic or machine GTAW temperbead welding.

Therefore, the potential for hydrogen-induced cracking is greatly reduced by using the machine GTAW process.

In the unlikely case that hydrogen cracking occurs, nondestructive examination of the weldment will be performed no sooner than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> following completion of the three tempering layers over the ferritic material, thereby providing assurance that the cracking would be identified, as discussed in Enclosure 1. Electric Power Research Institute has documented their technical basis in Technical Report 1013558 (Reference 8).

Cold Restraint Cracking Cold cracking generally occurs during cooling at temperatures approaching ambient temperature. As stresses build under a high degree of restraint, cracking may occur at defect locations. Brittle microstructures with low ductility are subject to cold restraint cracking.

However, the ambient temperature temperbead process is designed to provide a sufficient heat inventory so as to produce the desired tempering for high toughness. Because the machine GTAW temperbead process provides precision bead placement and control of heat, the toughness and ductility of the HAZ will typically be superior to the base material.

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ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

Therefore, the resulting structure will be appropriately tempered to exhibit toughness sufficient to resist cold cracking.

Exceptions to ASME Code Case N-740-2, Appendix I Conditions The ambient temperature temperbead technique of Code Case N-638-1 was conditionally approved by the NRC in Regulatory Guide 1.147, Revision 15. The proposed ambient temperature temperbead welding technique of Enclosure 2 is identical to Code Case N-638-1 with the following exceptions:

• Code Case N-638-1, paragraph 1.0(a) limits the maximum area of an individual weld to 100 square inches. Code Case N-740-2, Appendix I limits the area to 500 square inches.

The proposed alternative expands the surface area to 700 square inches or greater as justified by residual stress analysis of the DMW and of the ferritic material for the actual component to be repaired, in accordance with the requirements of EPRI Report 1011898 (Reference 9). The technical basis for this change is provided in Enclosure 4.

" Code Case N-638-1, paragraph 1.0(a) states that "the depth of the weld shall not be greater than one-half of the ferritic base metal thickness." Because the proposed alternative applies to deposition of weld overlays for which there are no weld or base material excavations, this limitation does not apply and is not included in Enclosure 2.

• When welding is to be performed in a pressurized environment (e.g., an enclosed environment that is pressurized to prevent leakage so that welding can be performed),

Code Case N-638-1, paragraph 2.1(b) requires that the pressurized environment be duplicated in the procedure qualification test assembly. Because this condition does not exist when applying weld overlays in the request, this requirement is not included in Enclosure 2.

" When welding is performed in the core beltline region of the reactor pressure vessel, Code Case N-638-1, paragraph 2.1(c) requires that the effects of irradiation on the properties of the materials be considered. Because weld overlays will not be applied to the core beltline region of the reactor pressure vessel, this requirement is not included in Enclosure 2.

" Code Case N-638-1, paragraph 2.1(h) requires the performance of Charpy V-notch testing of the ferritic weld metal of the procedure qualification test coupon. Because austenitic weld metal (i.e., Alloy 52 "Modified") will be used to fabricate the proposed weld overlays, this requirement does not apply and is not included in Enclosure 2.

" Code Case N-638-1, paragraph 2.10) specifies acceptance criteria for Charpy V-notch tests of the HAZ. According to paragraph 2.1(j), the "average values of the three HAZ impact tests shall be equal to or greater than the average values of the three unaffected base metal tests." Although not explicitly stated, the average values referred to in paragraph 2. 1(j) are the average lateral expansion values of the HAZ and base material specimens. Because this is the case, the acceptance criteria for Charpy V-notch testing of the HAZ is also based on average lateral expansion values in the proposed alternative.

The technical basis for this change is provided in Enclosure 4.

• Code Case N-638-1, paragraph 3.0(c) requires the deposition and removal of at least one weld reinforcement layer for "similar materials" (i.e., ferritic materials). This requirement is only applicable when welding is performed using ferritic filler weld metal.

When temperbead welding is performed with ferritic filler metal, each ferritic weld layer 10

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05) must be tempered by the heat supplied from a subsequent weld layer. Because the last layer of a weld or weld repair would be untempered without the deposition of one additional weld layer, paragraph 3.0(c) requires the deposition and removal of a reinforcement layer to provide the required tempering. Since only austenitic filler metal (i.e., Alloy 52M) will be used to fabricate the proposed weld overlays, depositing and removing a weld reinforcement layer is not required. Therefore, this requirement is not included in Enclosure 2.

e Code Case N-638-1, paragraph 3.0 does not specifically address monitoring or verification of welding interpass temperatures. Because this is the case, interpass temperature controls are specified in Enclosure 2. The proposed interpass temperature controls are based on field experience with depositing weld overlays. Interpass temperature beyond the third layer has no impact on the metallurgical properties of the ferritic steel HAZ.

• As an alternative to the examination requirements of Section 4.0 of Code Case N-638-1, the weld overlay will be examined in accordance with the examination and inspection requirements of Enclosure 1, Section 3.0. The suitability of the proposed examinations is described below.

3. Suitability of Proposed Nondestructive Examination The length, surface finish, and flatness requirements of the weld overlay will be specified in the design to provide for examination volume of the weld overlay as shown in Enclosure 1, Figures 1 and 2. Furthermore, the examinations and inspections specified in this proposed alternative will provide adequate assurance of structural integrity for the following reasons:

e Weld overlays have been used for repair and mitigation of cracking in BWRs since the early 1980s. In Generic Letter 88-01, NRC Position on IntergranularStress Corrosion Cracking (IGSCC) in BWR Austenitic Stainless Steel Piping,the NRC approved the use of Section XI acceptance standards for determining the acceptability of installed weld overlays.

• The ultrasonic examinations performed in accordance with the proposed alternative are in accordance with ASME Section XI, Appendix VIII, Supplement 11 as implemented through the PDI. These examinations are considered more sensitive for detecting fabrication and service-induced flaws than the ASME Section III radiographic or ultrasonic examination methods. Furthermore, construction-type flaws have been included in the PDI qualification sample sets for evaluating procedures and personnel.

• American Society of Mechanical EngineersSection XI has developed specific acceptance criteria and evaluation methodology to be utilized with the results from these more sensitive examinations. They consider the materials in which the flaw indications are detected, the orientation and size' of the indications, and ultimately their potential structural effects on the component. The acceptance criteria include' allowable flaw indication tables for planar flaws (Table IWB-3514-2) and for laminar flaws (Table IWB-3514-3).

• A laminar flaw is defined in ASME Section XI as a flaw oriented within 100 of a plane parallel to the surface of the component. This definition is applicable to welds and weld overlays as well as base materials. The standard imposed for evaluating laminar flaws in ASME Section XI is more restrictive than the ASME Section III standard for evaluating 11

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05) laminations. The ASME Section XI laminar flaw standards, Table IWB-3514-3, are supplemented in Enclosure 1 such that the total laminar flaw shall not exceed 10% of the weld overlay surface area and no linear dimension of the laminar flaw shall exceed 3 in.

For weld overlay areas where examination is precluded by the presence of the flaw, it is required to postulate the area as being cracked.

Any planar flaws found during either the weld overlay acceptance or preservice examinations are required to meet the preservice standards of Table IWB-3514-2. In applying the planar flaw standards, the thickness of the component will be defined as the thickness of the weld overlay and the issue of any flaws masked from examination will also be addressed as a part of the proposed alternative.

Weld overlays for the repair of cracks in piping are not addressed by ASME Section III.

American Society of Mechanical EngineersSection III utilizes nondestructive examination procedures and techniques with flaw detection capabilities that are well within the practical limits of workmanship standards for welds. These standards are most applicable to volumetric examinations conducted by radiographic examination.

Radiography of weld overlays is not appropriate because of the potential for radioactive material in the RCS and water in piping and components. The ASME Section III acceptance standards are written for a range of fabrication flaws including lack of fusion, incomplete penetration, cracking, slag inclusions, porosity, and concavity. However, experience and fracture mechanics have demonstrated that many of the flaws that are rejected using ASME Section III acceptance standards do not have a significant effect on the structural integrity of the component. Furthermore, utilizing ASME Section III acceptance standards on weld overlays would be inconsistent with years of NRC precedence and is without justification given the evidence of past NRC approvals and operating experience.

B. Proposed Alternative to ASME Section XI Appendix VIII, Supplement 11 Appendix VIII, Supplement 11 of the 2001 Edition of ASME Section XI specifies requirements for performance demonstration of ultrasonic examination procedures, equipment, and personnel used to detect and size flaws in full structural overlays of wrought austenitic piping welds. Calvert Cliffs intends to modify the Appendix VIII, Supplement 11 qualification requirements by the proposed alternatives in the PDI Program as indicated in Enclosure 5 of this request to comply with the EPRI PDI initiatives. Therefore, the PDI initiatives to ASME Section XI Appendix VIII, Supplement 11 as described in Enclosure 5 will be used for qualification of ultrasonic examinations used to detect and size flaws in the FSWOLs of this request.

VII. CONCLUSION Calvert Cliffs believes that the proposed alternatives of this request provide an acceptable level of quality and safety. The weld overlays will be installed using Nickel Alloy 52M filler metal that is resistant to PWSCC. While this is the case, the overlays will also create compressive residual stresses on the inner portion of the original weld, providing a condition that results in retarding or arresting crack growth, and minimizing the initiation of new PWSCC. Finally, preservice and ISI of the weld overlay will be performed to ensure structural integrity is maintained. Therefore, Calvert Cliffs requests that the NRC staff authorize the proposed alternative in accordance with 10 CFR 50.5 5a(a)(3)(i).

12

ATTACHMENT (1)

RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES (ISI-04-05)

VIII. REFERENCES

1. Fourth Interval Inservice Inspection Program Plan for Calvert Cliffs Nuclear Power Plant Units 1

& 2, Rev. 0

2. ASME Code,Section XI, 2004 Edition, with no Addenda

3. Letter from Richard J. Laufer (NRC) to James A. Spina (CCNPP), dated June 28, 2006 containing, "Safety Evaluation by the Office of Nuclear Reactor Regulation Regarding Alternative Repair and Examination Techniques for Structural Weld Overlay Calvert Cliffs Nuclear Power Plant, Inc.

Docket Numbers 50-317 and 50-318

4. EPRI Report 1015009, Primary System Piping Butt Weld Inspection and Evaluation Guideline (MRP-139 Revision 1), December 2008

5. EPRI Report 1016602, Technical Basis for Preemptive Weld Overlays for Alloy 82/182 Butt Welds in PWRs (MRP-169, Revision 1), June 2008

6. ASME Section XI, 2001 Edition is used for Appendix VIII, "Performance Demonstration for Ultrasonic Examinations Systems"

7. EPRI Report GC-111050, Ambient Temperature Preheat for Machine GTAW Temperbead Applications, November 1998

8. EPRI Report 1013558, Temper Bead Welding Applications - 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> Hold for Ambient Temperature Temper Bead Welding, December 2006

9. EPRI Report 1011898, "RRAC Code Justification for the Removal of the 100 Square Inch Temperbead Weld Limitation," November 2005 IX ENCLOSURES

1. Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

2. Proposed Ambient Temperature Temperbead Technique

3. Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure 1 for Full Structural Weld Overlays

4. Technical Basis for Alternatives to ASME Code Case N-638-1, Ambient Temperature Temperbead Welding

5. Comparison of ASME Section XI Appendix VIII, Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay 13

ENCLOSURE (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

Calvert Cliffs Nuclear Power Plant, LLC May 18, 2010

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2) 1.0 GENERAL REQUIREMENTS 1.1 Definitions (a) Full Structural Weld Overlay. Deposition of weld reinforcement on the outside diameter of the piping, component, or associated weld such that the weld reinforcement is capable of supporting the design loads, without consideration of the piping, component, or associated weld beneath the weld reinforcement. Full structural weld overlay can either be mitigative or repair weld overlay as defined in 1.1(b) and (c).

(b) Mitigative Weld Overlay. Weld overlay that is applied over material with no inside surface connected flaws found during an examination performed in accordance with 2.1 (d), prior to the weld overlay being applied.

(c) Repair Weld Overlay. Weld overlay that is applied over material with an inside surface connected flaw or subsurface defect, or where a pre-weld overlay examination is not performed.

(d) SCC Susceptible Materials. For this application, the stress corrosion cracking (SCC) susceptible materials are UNS N06600, N06082, or W86182 in the pressurized water reactor primary water environment.

1.2 General Overlay Requirements (a) A full structural weld overlay shall be applied by deposition of weld reinforcement (weld overlay) on the outside surface of circumferential welds. The overlay is to be applied to austenitic nickel alloy and austenitic stainless steel welds between the following:

(1) P-No. 8 or P- No. 43 and P-Nos. 1 or 3 (2) P-No. 8 and P-No. 43 (3) Between P-No. 1 and 3 materials (b) If a weld overlay on any of the material combinations in 1.2(a) obstructs a required examination of an adjacent P-No. 8 to P-No. 8 weld, the overlay may be extended to include overlaying the adjacent weld.

(c) Weld overlay filler material shall be austenitic nickel alloy (28% Cr min., ERNiCrFe-7/7A) meeting the requirements of 1.2(e)(1) or (2), as applicable, applied 360 °around the circumference of the item, and shall be deposited using a Welding Procedure Specification for groove welding, qualified in accordance with the Construction Code and Owner's Requirements identified in the Repair/Replacement Plan. As an alternative to the post-weld heat treatment requirements of the Construction Code and Owner's Requirements, the provisions for "Ambient Temperature Temperbead Welding" may be used on the ferritic nozzle as described in Enclosure 2.

(1) For P-No. 1 base materials, the Construction Code PWHT exemptions permitted for circumferential butt welds may be applied to exempt the weld overlay from PWHT, with the following clarifications:

(a) The nominal weld thickness is defined as the maximum overlay 'thickness applied over the ferritic base material.

(b) The base material thickness is defined as the maximum thickness of the ferritic

. material where the overlay is applied.

(2) If ambient temperature temperbead welding is used, Enclosure 2 shall be used.

1

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

(d) Prior to deposition of the weld overlay, the surface to be weld overlaid shall be examined using the liquid penetrant method. Indications with major dimensions greater than 1/16 in.

(1.5 mm) shall be removed, reduced in size, or weld repaired in accordance with the following requirements:

(1) One or more layers of weld metal shall be applied to seal unacceptable indications in the area to be repaired with or without excavation: The thickness of these layers shall not be Used in meeting weld reinforcement design thickness requirements. Peening the unacceptable indication prior to welding is permitted.

(2) If weld repair of indications identified in 1.2(d) is required, the area where the weld overlay is to be deposited, including any local weld repairs or initial weld overlay layer, shall be examined by the liquid penetrant method. The area shall contain no indications with major dimensions greater than 1/16 in. (1.5 mm) prior to application of the structural layers of the weld overlay.

(3) To reduce the potential of hot cracking when applying an austenitic nickel alloy over P-No. 8 base metal, it is permissible to apply a layer or multiple buffer (transitional) layers of austenitic stainless steel filler material over the austenitic stainless steel base metal. The thickness of these layers shall not be used in meeting weld reinforcement design thickness requirements. The filler material used shall meet the minimum requirements for delta ferrite.

(e) Weld overlay deposits shall meet the following requirement:

(1) The austenitic nickel alloy weld overlay shall consist of at least two weld layers deposited using a filler material with a Cr content of at least 28%. The first layer of weld metal deposited may not be credited toward the required thickness.

Alternatively, a first diluted layer may be credited toward the required thickness, provided the portion of the layer over the austenitic base material, austenitic filler material weld, and the associated dilution zone from an adjacent ferritic base material contain at least 24% Cr, and the Cr content of the deposited weld metal is determined by chemical analysis of the production weld or of a representative coupon taken from a mockup prepared in accordance with the Welding Procedure Specification for the production weld.

(f) This relief is only for welding in applications predicted not to have exceeded thermal neutron (E > 1.0 MeV) fluence of l x 1017 neutrons per cm 2 prior to welding.

(g) A new weld overlay shall not be installed over the top of an existing weld overlay that has been in service.

2.0 CRACK GROWTH AND DESIGN 2.1 Crack Growth Calculation of Flaws in the Original Weld or Base Metal. The size of all flaws detected or postulated in the original weld or base metal shall be used to define the life of the overlay. The inspection interval shall be longer than the shorter of the life of the overlay or the period specified in 3(c). Crack growth due to both stress corrosion and fatigue shall be evaluated.

Flaw characterization and evaluation shall be based on the examination results or postulated flaw, as described below. If the flaw is at or near the boundary of two different materials, evaluation of flaw growth in both materials is required.

(a) For repair overlays, the initial flaw size for crack growth in the original weld or base metal shall be based on the as-found flaw or postulated flaw, if no pre-overlay examination is performed.

2

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

(b) For postulated flaws, the axial flaw length shall be 1.5 in. (38 mm) or the combined width of the weld plus buttering plus any adjacent SCC susceptible material, whichever is greater.

The circumferential flaw length shall be assumed to be 3600. The depths associated with these lengths are specified in 2.1 (c) and 2. 1(d).

(c) If an Appendix VIII, Supplement 10, or Supplement 2, as applicable, ultrasonic examination is performed prior to application of the overlay, and no inside-surface-connected planar flaws are discovered, initial flaws originated from the inside surface of the weldment equal to 10% of the original wall thickness shall be assumed in both the axial and circumferential directions, and the overlay shall be considered mitigative.

(d) If an Appendix VIII, Supplement 10, or Supplement 2, as applicable, ultrasonic examination is not performed prior to application of the overlay, initial inside-surface-connected planar flaws equal to at least 75% through the original wall thickness shall be assumed, in both the axial and circumferential directions, and the overlay shall be considered a repair. For cast austenitic stainless steel items, a 100% through-wall flaw shall be assumed unless the subsequent inservice inspection schedule is modified as discussed in 3.0(c)(8).

(e) There may be circumstances in which an overlay examination is performed using an ultrasonic examination procedure qualified in accordance with Appendix VIII, Supplement 11 for depths greater than the outer 25% of the original wall thickness (Figure 2). For such cases, the initial flaw depths shall be assumed to be the detected depth found by the Appendix VIII, Supplement 11 qualified examination, plus the postulated worst-case flaw in the region not covered by the Appendix VIII ultrasonic examination.

(f) In determining the life of the overlay, any inside-surface-connected planar flaw found by the overlay preservice inspection of 3.0(b) that exceeds the depth of (c), (d), or (e) above shall be used as part of the initial flaw depth. The initial flaw depth assumed is the detected flaw depth plus the postulated worst-case flaw depth in the region of the pipe wall thickness that was not examined using an ultrasonic examination procedure meeting Appendix VIII for that region. An overlay meeting this condition shall be considered a repair, rather than mitigation.

2.2 Structural Design and Sizing of the Overlay. The design of the weld overlay shall satisfy the following, using the assumptions and flaw characterization requirements in 2.1. The following design analysis shall be completed in accordance with IWA-4311:

(a) The axial length and end slope of the weld overlay shall cover the weld and heat affected zones on each side of the weld, as well as any SCC-susceptible base material adjacent to the weld, and provide for load redistribution from the item into the weld overlay and back into the item without violating applicable stress limits of NB-3200. Any laminar flaws in the weld overlay shall be evaluated in the analysis to ensure that load redistribution complies with the above. These requirements will usually be satisfied if the weld overlay full thickness length extends axially beyond the SCC-susceptible material or projected flaw by at least 0.75,rRit, where R is the outer radius of the item and t is the nominal wall thickness of the item at the applicable side of the overlay (i.e., R and t of the nozzle on the nozzle side and R and t of the safe-end on the safe-end side).

(b) Unless specifically analyzed in accordance with 2.2(a), the end transition slope of the overlay shall not exceed 30'.

3

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

(c) For full structural overlays, the assumed flaw in the underlying base material or weld shall be based on the limiting case of 2.2(c)(1) and (2) that results in the larger required overlay thickness.

(1) 100% through-wall circumferential flaw for the entire circumference (2) 100% through-wall flaw with length of 1.5 in. (38 mm) or the combined width of the weld plus buttering plus any SCC-susceptible material, whichever is greater, in the axial direction (d) The overlay design thickness shall be verified, using only the weld overlay thickness conforming to the deposit analysis requirements of 1.2(e). The combined wall thickness at the weld overlay, any postulated worst-case planar flaws under the laminar flaws in the weld overlay, and the effects of any discontinuity (e.g., another weld overlay or reinforcement for a branch connection) within a distance of 2.5JR, from the toes of the weld overlay, including the flaw size assumptions defined in 2.2(c) above, shall be evaluated and shall meet the requirements of IWB-3640, IWC-3640, or IWD-3640, as applicable.

(e) The effects of any changes in applied loads, as a result of weld shrinkage from the entire overlay, on other items in the piping system (e.g., support loads and clearances, nozzle loads, and changes in system flexibility and weight due to the weld overlay) shall be evaluated.

Existing flaws previously accepted by analytical evaluation shall be evaluated in accordance with IWB-3640, IWC-3640, or IWD-3640, as applicable.

3.0 EXAMINATION In lieu of all other examination requirements, the examination requirements of this application shall be met for the life of the overlay. Nondestructive examination methods shall be in accordance with IWA-2200, except as specified herein. Nondestructive examination personnel shall be qualified in accordance with IWA-2300. Ultrasonic examination procedures and personnel shall be qualified in accordance with Appendix VIII, Supplement 11. The examination shall be performed to the maximum extent practicable, for axial and circumferential flaws. If 100% coverage of the required volume for axial flaws cannot be achieved, but essentially 100% coverage for circumferential flaws (100% of the susceptible volume) can be achieved, the examination for axial flaws shall be performed to achieve the maximum coverage practicable, with limitations noted in the examination report. The examination coverage requirements shall be considered to be met. For cast stainless steel components for which no supplement is available in Appendix VIII, the weld volume shall be examined using Appendix VIII procedures to the maximum extent practicable.

(a) Acceptance Examination (1) The weld overlay shall have a surface finish of 250 gin. (6.3 grm) root mean square or better and contour that permits ultrasonic examination in accordance with procedures qualified in accordance with Appendix VIII. The weld overlay shall be inspected to verify acceptable configuration.

(2) The weld overlay and the adjacent base material for at least 1/2 in. (13 mm) from each side of the overlay shall be examined using the liquid penetrant method. The weld overlay shall satisfy the surface examination acceptance criteria for welds of the Construction Code or NB-5300. The adjacent base material shall satisfy the surface examination acceptance criteria for base material of the Construction Code or NB-2500. If ambient temperature temper bead welding is performed, the liquid 4

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2) penetrant examination of the completed weld overlay shall be conducted no sooner than 48 hr following completion of the three tempering layers over the ferritic steel.

(3) The examination volume A-B-C-D in Figure l(a) shall be ultrasonically examined to assure adequate fusion (i.e., adequate bond) with the base material and to detect welding flaws, such as interbead lack of fusion, inclusions, or cracks. The interface C-D shown between the overlay and weld includes the bond and HAZ from the overlay. If ambient temperature temper bead welding is performed, the ultrasonic examination shall be conducted no sooner than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> following completion of the three tempering layers over the ferritic steel. Planar flaws detected in the weld overlay acceptance examination shall meet the preservice examination standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness, t1 or t 2 defined in Figure l(b), shall be used as the nominal wall thickness in IWB-3514, provided the base material beneath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to SCC. For susceptible material, tj shall be used.

If a flaw in the overlay crosses the boundary between the two regions, the more conservative of the two dimensions (t, or t2) shall be used.

(4) Laminar flaws in the weld overlay shall meet the following requirements:

(a) The acceptance standards of IWB-3514 shall be met, with the additional limitation that the total laminar flaw area shall not exceed 10% of the weld surface area and that no linear dimension of the laminar flaw area shall exceed the greater of 3 in. (76 mm) or 10% of the pipe circumference.

(b) For examination volume A-B-C-D in Figure 1(a), the reduction in coverage due to laminar flaws shall be less than 10%. The uninspectable volume is the volume in the weld overlay underneath the laminar flaws for which coverage cannot be achieved with the angle beam examination method.

(c) Any uninspectable volume in the weld overlay shall be assumed to contain the largest radial planar flaw that could exist within that volume. This assumed flaw shall meet the preservice examination acceptance standards of IWB-3514, with nominal wall thickness as defined above the planar flaws. Alternatively, the assumed flaw shall be evaluated and meet the requirements of IWB-3640, IWC-3640, and IWD-3640, as applicable. Both axial and circumferential planar flaws shall be assumed.

(5) After completion of all welding activities, VT-3 visual examination shall be performed on all affected restraints, supports, and snubbers, to verify that design tolerances are met.

(b) PreserviceInspection (1) The examination volume in Figure 2 shall be ultrasonically examined. The angle beam shall be directed perpendicular and parallel to the piping axis, with scanning performed in four directions, to locate and size any planar flaw that have propagated into the outer 25% of the base metal thickness or into the weld overlay. For weld overlays on cast austenitic stainless steel base materials, if a 100% through-wall flaw is used for crack growth, only planar flaws that have propagated into the weld overlay, or are in the overlay, are required to be located and sized.

(2) The preservice examination acceptance standards of IWB-3514 shall be met for the weld overlay. In applying the acceptance standards to planar indications, the 5

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2) thickness, tj or t2, defined in Figure l(b), shall be used as the nominal wall thickness in IWB-3514, provided the base material beneath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to SCC. For susceptible material, tl shall be used.

Planar flaws in the outer 25% of the base metal thickness shall meet the design analysis requirements of 2.2.

(3) The flaw evaluation requirements of IWB-3640, IWC-3640, or IWD-3640 shall not be applied to planar flaws, identified during preservice examination, that exceed the preservice examination acceptance standards of IWB-3514.

(c) Inservice Inspection (1) The weld overlay examination shall be added to the inspection plan. The weld overlay inspection interval shall not be greater than the life of the overlay as determined in 2.1 above. All weld overlays shall be examined prior to the end of their design life.

(2) The weld overlay examination volume in Figure 2 shall be ultrasonically examined during the first or second refueling outage following application. Alternatively, for mitigative weld overlays, in which pre-overlay examinations are performed in accordance with 2.1(c), post-overlay examinations are performed in accordance with 3.0(a) and 3.0(b), and no inside-surface-connected planar flaws are discovered, the overlay may be placed immediately into the population to be examined in accordance with 3.0(c)(5).

(3) The weld overlay examination volume in Figure 2 shall be ultrasonically examined to determine if any new or existing planar flaws have propagated into the outer 25% of the base material thickness or into the overlay. The angle beam shall be directed perpendicular and parallel to the piping axis, with scanning performed in four directions.

(4) The weld overlay shall meet the inservice examination acceptance standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness, t1 or t 2 , defined in Figure l(b), shall be used as the nominal wall thickness in IWB-3514, provided the base material beneath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to SCC. For susceptible material, t1 shall be used.

If the acceptance standards of IWB-3514 cannot be met, the weld overlay shall meet the acceptance standards of IWB-3600, IWC-3600, or IWD-3600, as applicable. If a planar flaw is detected in the outer 25% of the base material thickness shall meet the design analysis requirements of 2.0. Any indication characterized as stress corrosion cracking in the weld overlay material is unacceptable.

(5) Weld overlay examination volumes in Figure 2 that show no indication of planar flaw growth or new planar flaws shall be placed into a population to be examined on a sample basis, except as required by 3.0(c)(1). Twenty-five percent of this population shall be examined once during each inspection interval.

(6) If inservice examinations reveal planar flaw growth, or new planar flaws, meeting the acceptance standards of IWB-3514, IWB-3600, IWC-3600, or IWB-3600, the weld overlay examination volume shall be re-examined during the first or second refueling outage following discovery of the growth or new flaws.

6

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

(7) For weld overlay examination volumes with unacceptable indications in accordance with 3.0(c)(4), the weld overlay and original defective weld shall be removed. A repair/replacement activity shall be performed in accordance with IWA-4000.

(8) If preservice and inservice examinations in accordance with American Society of Mechanical Engineers (ASME)Section XI, Appendix VIII, Supplement I I cannot be performed for the entireweld overlay examination volume in Figure 2 because of cast austenitic stainless steel items, and a 100% initial flaw assumption is not used in the crack growth evaluation of 2.1, a 75% through-wall depth may be assumed in the crack growth calculation, provided that the required examination volume is examined at a higher frequency than the requirements in paragraph 3.0(c)(1). The subject weld shall be ultrasonically examined during the first or second refueling outage following the weld overlay installation. If ultrasonic examination is performed prior to weld overlay installation and after installation without detecting any planar flaws in the original weld or the weld overlay, then the ultrasonic examination during the first or second refueling outage is not required. After the first inservice examination, the required examination volume shall be ultrasonically examined every ten years from the date of the installation until such time when ultrasonic examination is qualified to examine the cast austenitic stainless steel portion of the required inspection volume in accordance with the performance demonstration requirements of ASME Code,Section XI, Appendix VIII. The inspection of the overlaid weld shall not be credited to satisfy the requirement of the 25% inspection sample every ten years of overlaid welds without cast stainless steel materials. After the required examination volume is examined by qualified ultrasonic examination for the cast austenitic stainless steel material and no planar flaws are detected, the weld may be placed in the 25%

inspection sample population in accordance with paragraph 3.0(c)(5).

(d) Additional Examinations. If inservice examinations reveal a defect, in accordance with 3.0(c)(4), planar flaw growth into the weld overlay design thickness, or axial flaw growth beyond the specified examination volume, additional weld overlay examination volumes, equal to the number scheduled for the current inspection period, shall be examined prior to return to service. If additional defects are found in the second sample, 50% of the total population of weld overlay examination volumes shall be examined prior to return to service. If additional defects are found, the entire remaining population of weld overlay examination volumes shall be examined prior to return to service.

4.0 PRESSURE TESTING A system leakage test shall be performed in accordance with IWA-5000.

5.0 DOCUMENTATION Use of this alternative shall be documented in the Repair/Replacement Plan.

7

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

Figure 1. Acceptance Examination Volume and Thickness Definitions End Transiticn Slope (not to excead 3D-Jegrees. unless analyzed)

D CC (a) Examination Volume A-B-C-D t2 (b) Thickness (11 and t 2 ) for Table IWB-3514-2 GENERAL NOTES:

(a) Dimension b is equivalent to the nominal thickness of the nozzle or pipe being overlaid, as appropriate.

(b) The nominal wall thickness is tl for flaws in E-F-G-H, and t2 for flaws in A-E-H-D or F-B-C-G.

(c) For flaws that span two examination volumes (such as illustrated at F-G), the t1 thickness shall be used.

(d) The weld includes the nozzle or safe end butter, where applied, plus any SCC-susceptible base material in the nozzle.

8

Enclosure (1)

Proposed Alternative for Full Structural Weld Overlays (Based on ASME Code Case N-740-2)

Figure 2. Preservice and Inservice Examination Volume Minimum 1/2 in. (13 mm) Minimum 1/2 in. (13 mm) (Note 1) tw As-found Flaw Examination Volume A-B-C-D GENERAL NOTE: The weld includes the nozzle butter, where applied.

NOTE:

(1) For axial or circumferential flaws, the axial extent of the examination volume shall extend at least 1/2 in. (13 mm) beyond the as-found flaw and at least 1/2 in. (13 mm) beyond the toes of the original weld, including weld end butter, where applied.

9

ENCLOSURE (2)

Proposed Ambient Temperature Temperbead Technique Calvert Cliffs Nuclear Power Plant, LLC May 18, 2010

Enclosure (2)

Proposed Ambient Temperature Temperbead Technique 1.0 GENERAL REQUIREMENTS (a) This enclosure applies to dissimilar austenitic filler metal welds joining P-No. 8 or P-No. 43 materials to P-No. I and P-No. 3 materials.

(b) The maximum area of an individual weld overlay based on the finished surface over the ferritic base material shall be 500 square inches unless a greater area is qualified as the result of a component specific finite element residual stress analyses per the requirements of Electric Power Research Institute Report 1011898 (Reference 1).

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

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

(e) Prior to welding, the area to be welded and a band around the area of at least 1-1/2 times the component thickness or 5 inches, whichever is less, shall be at least 50'F (100 C).

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

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

2.0 WELDING QUALIFICATIONS Welding procedures and welding operators shall be qualified in accordance with American Society of Mechanical Engineers (ASME)Section IX and the requirements of Sections 2.1 and 2.2 below.

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

(b) The maximum interpass temperature for the first three layers of the test assembly shall be 150-F (66-C).

(c) The weld overlay shall be qualified using a groove weld coupon. The test assembly groove depth shall be at least 1 in. (25 mm). The test assembly thickness shall be at least twice the test assembly groove depth. The test assembly shall be large enough to permit removal of the required test specimens. The test assembly dimensions on either side of the groove shall be at least 6 in. (150 mm). The qualification test plate shall be prepared in accordance with Figure 2-1.

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

1

Enclosure (2)

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

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

(2) If the material thickness permits, the axis of a specimen shall be inclined to allow the root of the notch to be aligned parallel to the fusion line.

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

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

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

(1) The welding procedure shall be requalified.

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

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

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

(a) The weld metal shall be deposited by the automatic or machine gas tungsten arc welding process.

(b) Dissimilar metal welds shall be made using F-No. 43 weld metal (QW-432) for P-No. 8 to P-No. 1 or to P-No. 3 weld joints.

(c) The area to be welded shall be buttered with a deposit of at least three layers to achieve at least 1/8 inch (3mm) overlay thickness with the heat input for each layer controlled to within

+/-10% of that used in the procedure qualification test. The heat input of the first three layers 2

Enclosure (2)

Proposed Ambient Temperature Temperbead Technique shall not exceed 45 kJ/in. (1.8 kJ/mm) under any conditions. Particular care shall be taken in the placement of the weld layers of the austenitic overlay filler material at the toe of the overlay to ensure that the HAZ and ferritic base metal are tempered. Subsequent layers shall be deposited with a heat input not exceeding that used for layers beyond the third layer in the procedure qualification.

(d) The maximum interpass temperature for field applications shall be 350'F (180 0C) for all weld layers regardless of the interpass temperature used during qualification.

(e) The interpass temperature shall be determined as follows:

(1) Direct temperature measurement (e.g., pyrometers, temperature-indicating crayons, and thermocouples) during welding or if direct measurement is impractical, one of the following methods shall be used to determine the interpass temperature:

(2) Heat-flow calculations using the variables listed below as a minimum (a) welding heat input (b) initial base material temperature (c) configuration, thickness, and mass of the item being welded (d) thermal conductivity and diffusivity of the materials being welded (e) arc time per weld pass and delay time between each pass (f) arc time to complete the weld (3) Measurement of the maximum interpass temperature on a test coupon that is no thicker than the item to be welded. The maximum heat input of the welding procedure shall be used in welding the test coupon.

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

4.0 REFERENCE

1. EPRI Report 1011898, "RRAC Code Justification for the Removal of the 100 Square Inch Temperbead Weld Limitation," November 2005 3

Enclosure (2)

Proposed Ambient Temperature Temperbead Technique Discard Transverse Side Bend Reduced Section Tensile Transverse Side Bend HAZ Charpy V-Notch Transverse Side Bend Reduced Section Tensile Transverse Side Bend Discard Figure 2-1. Qualification Test Plate 4

ENCLOSURE (3)

Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure 1 for Full Structural Weld Overlays Calvert Cliffs Nuclear Power Plant, LLC May 18, 2010

Enclosure (3)

Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure 1 for Full Structural Weld Overlays Code Case N-504-3 and Appendix Q of ASME Section XI Proposed Alternative of Enclosure 1 Code Case N-504-3 provides requirements for reducing a defect to a flaw of The proposed alternative of Enclosure 1 provides requirements for installing a full acceptable size by deposition of weld reinforcement (weld overlay) on the structural weld overlay by depositing weld reinforcement (weld overlay) on the outside surface of the pipe using austenitic stainless steel filler metal as an outside surface of the item using Nickel Alloy 52M filler metal. Enclosure 1 is alternative to defect removal. Code Case N-504-3 is applicable to applicable to dissimilar metal welds (DMWs) associated with ferritic and austenitic austenitic stainless steel piping only. According to Regulatory Guide stainless steel materials. It is also applicable to similar metal welds in austenitic 1.147, the provisions of Non-mandatory Appendix Q of American Society stainless steels. The proposed alternative of Enclosure 1 is based on Code Case of Mechanical Engineers (ASME)Section XI must also be met when using N-740-2, and Materials Reliability Program (MRP)-139, Revision 1 and MRP-169, this Case. Therefore, the Code Case N-504-3 requirements presented below Revision 1.

have been supplemented by Appendix Q of ASME Section XI.

General Requirements 1.0 General Requirements Code Case N-504-3 and Appendix Q are only applicable to P-No. 8 As specified in paragraph 1.2(a) of Enclosure 1, the proposed alternative is austenitic stainless steels. applicable to dissimilar metal 82/182 welds joining P-No. 1 or P-No. 3 to P-No. 8 materials. It is also applicable to austenitic stainless steel welds joining P-No. 8 materials.

Basis: Code Case N-504-3 and Appendix Q are applicable to austenitic weld overlays of P-No. 8 austenitic stainless steel materials. Based on Code Case N-740-2, the "proposed alternative of Enclosure 1 is specifically written to address the application of weld overlays over DMWs and austenitic stainless steel welds.

According to paragraph (b) of Code Case N-504-3 as supplemented by The weld filler metal and procedure requirements of Enclosure 1, paragraph 1.2(c) is Appendix Q, weld overlay filler metal shall be low carbon (0.035% max.) equivalent to Code Case N-504-3 and Appendix Q except as noted below:

austenitic stainless steel applied 3600 around the circumference of the pipe, , Weld overlay filler metal shall be austenitic Nickel Alloy 52M (ERNiCrFe-7A) and shall be deposited using a Welding Procedure Specification for groove filler metal which has a chromium content of at least 28%.

welding, qualified in accordance with the Construction Code and Owner's As an alternative to post-weld heat treatment, the provisions for ambient temperature Requirements and identified mn the Repair/Replacement Plan. temperbead welding may be used on the ferritic nozzle as described in Enclosure 2.

Basis: The weld overlay will be deposited with ERNiCrFe-7A (Alloy 52M) filler metal. It has been included into ASME Section IX as F-No. 43 filler metals.

Containing 28.0 - 31.5% chromium (roughly twice the chromium content of 82/182 filler metal), this filler metal has excellent resistance to primary water stress corrosion cracking (PWSCC). This point has been clearly documented in Electric Power Research Institute Technical Report MRP-115, Section 2.2 (Reference 1).

Regarding the Welding Procedure Specification (WPS), paragraph 2.1(c) of Enclosure 2 provides clarification that the WPS used for depositing weld overlays must be qualified as a groove welding procedure to ensure that mechanical properties of the WPS are appropriately established. Where welding is performed on ferritic nozzles, an ambient temperature temperbead WPS will be used. Suitability

Enclosure (3)

Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure 1 for Full Structural Weld Overlays Code Case N-504-3 and Appendix Q of ASME Section XI Proposed Alternative of Enclosure 1 of an ambient temperature temperbead WPS is addressed in Section VI.A.2 of this Request.

According to paragraph (e) of Code Case N-504-3 as supplemented by The weld overlay described in Enclosure 1 is deposited using Nickel Alloy 52M Appendix Q, the weld reinforcement shall consist of at least two weld filler metal instead of austenitic stainless steel filler metals. Therefore, the basis for layers having as-deposited delta ferrite content of at least 7.5 FN. The first crediting the first layer towards the required design thickness will be based on the layer of weld metal with delta ferrite content of at least 7.5 FN shall chromium content of the nickel alloy filler metal. According to paragraph 1.2(e) of constitute the first layer of the weld reinforcement that may be credited Enclosure 1 the first layer of Nickel Alloy 52M deposited weld metal may be toward the required thickness. Alternatively, first layers of at least 5 FN credited toward the required thickness provided the portion of the layer over the provided the carbon content is determined by chemical analysis to be less austenitic base material, austenitic weld, and the associated dilution zone from an than 0.02%. adjacent ferritic base material contains at least 24% chromium. The chromium content of the deposited weld metal may be determined by chemical analysis of the production weld or from a representative coupon taken from a mockup prepared in accordance with the WPS for the production weld.

Basis: The weld overlay will be deposited with ERNiCrFe-7A (Alloy 52M) filler metal. Credit for the first weld layer may not be taken toward the required thickness unless it has been shown to contain at least 24% chromium. This is a sufficient amount of chromium to prevent PWSCC. Section 2.2 of Electric Power Research Institute Technical Report MRP- 115 (Reference 1) states the following: "The only well explored effect of the compositional differences among the weld alloys on PWSCC is the influence of chromium. Buisine, et al. evaluated the PWSCC resistance of nickel-based weld metals with various chromium contents ranging from about 15% to 30% chromium. Testing was performed in doped steam and primary water. Alloy 182, with about 14.5% chromium, was the most susceptible.

Alloy 82 with 18-20% chromium took three or four times longer to crack. For chromium contents between 21 and 22%, no stress corrosion crack initiation was observed..."

Design and Crack Growth Considerations 2.0 Design and Crack Growth Considerations The design and flaw characterization provisions of Code Case N-504-3, The design and flaw evaluation provisions in the proposed alternative of paragraphs (f) and (g) as supplemented by Appendix Q are summarized Section Al.2 are the same as Code Case N-504-3 as supplemented in Appendix Q below: with the exceptions below.

(i) Flaw characterization and evaluation are based on the as-found flaw. e For crack growth evaluations, if the flaw is at or near the boundary of two Flaw evaluation of the existing flaws is based on IWB-3640 for the different materials, evaluation of flaw growth in both materials is required.

design life.

• For design, flaws shall be assumed to be 100% through the original wall

• Multiple circumferential flaws shall be treated as one flaw of thickness for the entire circumference. Unless specifically analyzed, the end length equal to the sum of the lengths of the individual flaws. transition slope of the overlay shall not exceed 300.

2

Enclosure (3)

Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure 1 for Full Structural Weld Overlays Code Case N-504-3 and Appendix Q of ASME Section XI Proposed Alternative of Enclosure 1

" Circumferential flaws are postulated as 100% through-wall for the Basis: Regarding the crack growth analysis, the proposed alternative of Enclosure 1 entire circumference with one exception. When the combined allows for the possibility that the flaw is at or near the boundary of the overlay length of circumferential flaws does not exceed 10% of the material, which is different than the base material. With regard to design, flaws are circumference, the flaws are only assumed to be 100% through- considered to be 100% through the original weld and no structural credit is taken for wall for the combined length of the flaws. the weld. The maximum transition end slope, without specific analysis, is limited to

" For axial flaws 1.5 inches or longer, or for five or more axial flaws 300 instead of 45' to minimize transition discontinuity stresses. All other of any length, the flaws shall be assumed to be 100% through-wall requirements are equivalent to Code Case N-504-3 as supplemented by Appendix Q.

for the axial length of the flaw and entire circumference of the pipe.

(ii) For four or fewer axial flaws less than 1.5 inches in length, the weld overlay thickness need only consist of two or more layers of weld metal meeting the deposit analysis requirements.

(iii) The axial length and end slope of the weld overlay shall cover the weld and heat affected zones on each side of the weld, and shall provide for load redistribution from the item into the weld overlay and back into the item without violating applicable stress limits of the Construction Code. Any laminar flaws in the weld overlay shall be evaluated in the analysis to ensure that load redistribution co 'plies with the above. These requirements are usually met if the weld overlay extends beyond the projected flaw by at least 0.75 (Rt)11 2.

(iv) Unless specifically analyzed, the end transition slope of the overlay shall not exceed 450, and a slope of not more than 1:3 is recommended.

(v) The overlay design thickness of items shall be based on the measured diameter, using only the weld overlay thickness conforming to the deposit analysis requirements. The combined wall thickness at the weld overlay, any planar flaws in the weld overlay, and the effects of any discontinuity (e.g., another weld overlay or reinforcement for a branch connection) within a distance of 0.75 (Rt)" 2 from the toes of the weld overlay, shall be evaluated and meet the requirements of IWB-, IWC-, or IWD-3640.

(vi) The effects of any changes in applied loads, as a result of weld shrinkage or existingý flaws previously accepted by analytical evaluation shall be evaluated in accordance with IWB-3640, IWC-3640, or IWD-3640, as applicable.

3

Enclosure (3)

Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure 1 for Full Structural Weld Overlays Code Case N-504-3 and Appendix Q of ASME Section XI Proposed Alternative of Enclosure 1 Examination and Inspection 3.0 Examination and Inspection Code Case N-504-3 does not include requirements for acceptance Enclosure 1, Sections 3.0 of the proposed alternative specifies requirements examination or inservice examination of weld overlays. Preservice applicable to weld acceptance examinations, preservice examinations, and inservice examination is addressed. However, Appendix Q, Article Q-4000 does examinations.

specify requirements applicable to weld acceptance examinations, preservice examinations, and inservice examinations.

Acceptance Examination 3.0(a) Acceptance Examination Q-41 00(c) states that the examination volume in Figure Q-4100-1 shall be The acceptance standards in paragraph 3.0(a)(3) of Enclosure 1 are identical to those ultrasonically examined to assure adequate fusion (i.e., adequate bond) with of paragraph Q-4100(c) except that paragraph 3.0(a)(3) includes requirements and the base metal and to detect welding flaws, such as inter-bead lack of clarifications that are not included in Appendix Q. First, it specifies that the fusion, inclusions, or cracks. Planar flaws shall meet the preservice ultrasonic examination shall be conducted at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after completing the examination standards of Table IWB-3514-2. third layer of the weld overlay when ambient temperature temperbead welding is used. Secondly, it provides the following clarifications:

" The interface C-D between the weld overlay and the weld includes the bond and the heat affected zone from the weld overlay.

• In applying the acceptance standards, wall thickness "t," shall be the thickness of the weld overlay.

Basis: Appendix Q is applicable to austenitic stainless steel materials only; therefore, ambient temperature temperbead welding would not be applicable. It is applicable to welding performed in the proposed alternative. When ambient temperature temperbead welding is performed, nondestructive examinations must be performed at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after completing the third layer of the weld overlay to allow sufficient time for hydrogen cracking to occur (if it is to occur). Technical justification for starting the 48-hour hold after completing the third layer of the weld overlay is provided in paragraph VI.A.2 of Attachment (1). The other two changes are simply clarifications that were added to ensure that the examination requirements were appropriately performed.

Q-41 00(c)(1) states that laminar flaws shall meet the acceptance standards The acceptance standards in paragraph 3.0(a)(4)(a) of Enclosure 1 are identical to of Table IWB-3514-3. paragraph Q-4100(c)(1) except that paragraph 3.0(a)(4)(a) includes the additional limitation that the total laminar flaw shall not exceed 10% of the weld surface area and that no linear dimension of the laminar flaw area exceeds 3.0 inches.

Basis: These changes were made to provide additional conservatism to the weld overlay examination and to reduce the size of the uninspectable volume beneath a laminar flaw. See paragraph VI.A.3 of Attachment (1) for additional information.

4

Enclosure (3)

Comparison of ASME Code Case N-504-3 and Appendix Q of ASME Section XI with the Proposed Alternative of Enclosure 1 for Full Structural Weld Overlays Code Case N-504-3 and Appendix Q of ASME Section XI Proposed Alternative of Enclosure 1 Q-41 00(c)(4) allows the performance of radiography in accordance with the The acceptance standards in paragraph 3.0(a) of Enclosure 1 do not include the Construction Code as an alternative to Q-4100(c)(3). radiographic alternative of paragraph Q-4100(c)(4).

Basis: The ultrasonic testing examinations performed in accordance with the proposed alternative are in accordance with ASME Section XI, Appendix VIII, Supplement 11 as implemented through the Performance Demonstration Initiative (PDI). These examinations are considered more sensitive for detection of defects, either from fabrication or service-induced, than either ASME Section III radiographic or ultrasonic methods. Furthermore, construction type flaws have been included in the PDI qualification sample sets for evaluating procedures and personnel. See Section VI.A.3 of Attachment (1) for additional justification.

Preservice Inspection 3.0(b) Preservice Inspection Q-4200(b) states that the preservice examination acceptance standards of The acceptance standards in paragraph 3.0(b)(2) of Enclosure 1 are identical to Table IWB-3514-2 shall be met for the weld overlay. Cracks in the outer paragraph Q-4200(b) except paragraph 3.0(b)(2) includes the following statement:

25% of the base metal shall meet the design analysis requirements of "In applying the acceptance standards, wall thickness, t1 , shall be the thickness of Q-3000. the weld overlay."

Basis: This provision is actually a clarification that the nominal wall thickness of Table IWB-3514-2 shall be considered the thickness of the weld overlay. It must be remembered that the acceptance standards were originally written for the welds identified in IWB-2500. Because IWB-2500 does not address weld overlays, this clarification was provided to avoid any potential confusion. However, defining the weld overlay thickness as the nominal wall thickness of Table IWB-3514-2 has always been the practice, since it literally becomes the new design wall of the piping or component nozzle.

Pressure Testing 4.0 Pressure Testing N-504-3 paragraph (h): The completed repair shall be pressure tested in The pressure testing requirements of Section 4.0 of Enclosure 1 are similar to accordance with IWA-5000. A system hydrostatic test is required if the paragraph (h) of Code Case N-504-3 except that only a system leakage test per flaw penetrated the pressure boundary. A system leakage test may be IWA-5000 is required.

performed if pressure boundary is not penetrated.

REFERENCE

1. MRP-1 15, "Materials Reliability Program: Crack Growth Rates for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) of Alloy 82, 182, and 132 Welds (MRP-1 15), 1006696, Final Report, September 2004" 5

ENCLOSURE (4)

Technical Basis for Proposed Alternatives to ASME Code Case N-638-1, Ambient Temperature Temperbead Welding Calvert Cliffs Nuclear Power Plant, LLC May 18, 2010

Enclosure (4)

Technical Basis for Proposed Alternatives to ASME Code Case N-638-1, Ambient Temperature Temperbead Welding

1. BASIS FOR AREA LIMITATION CHANGE TO A MINIMUM OF 500 SQUARE INCHES IWA-4600 and versions of American Society of Mechanical Engineers (ASME) Code Case N-638 through Revision 2 contained a 100 square-inch limitation on surface area of a temperbead weld over ferritic base metal. Code Case N-638 Revision 3 changed the surface area limitation to 500 square inches or greater if required. The 500 square-inch surface area limitation was incorporated into Code Case N-740-2 and is included in Enclosure 2. It is anticipated that some overlays applied under this alternative will be greater than 100 square inches and likely greater than 500 square inches. For overlays requiring greater than 500 square inches of surface area on the P-No. 1 or P-No. 3 material, a component specific finite element analysis will be performed to assure that the residual stress benefit is obtained, per the requirements of the white paper discussed in the following paragraph.

Technical justification for allowing weld overlays on ferritic materials with surface areas up to 500 square inches is provided in the white paper supporting the changes in ASME Code Case N-638-3 and Electric Power Research Institute Report 1011898 (Reference 1). The ASME white paper notes that the original limit of 100 square inches in Code Case N-63 8-1 was arbitrary. It cites evaluations of a 12-inch diameter nozzle weld overlay to demonstrate adequate tempering of the weld heat affected zone (HAZ) (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 Nuclear Regulatory Commission approved and applied to dissimilar metal weld (DMW) nozzles in several BWR and pressurized water reactor (Section 3c of the white paper) applications. 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 Electric Power Research Institute Report also notes that the ASME Code should provide an option to users to justify repairs beyond 500 square inches by additional analysis and evaluation. That analysis and evaluation will be performed if the 500 square inch limit is exceeded, by means of a finite element residual stress analysis on the actual component configuration being evaluated.

It is important to note that the above theoretical arguments and empirical data have been verified in practice by extensive field experience with temperbead weld overlays, with ferritic material coverage ranging from less than 10 square inches up to and including 325 square inches. The table below provides a partial list of such applications.

Table 4.1 Dissimilar Metal Weld Overlay Experience Nozzle Date Plant Component Diameter (in)

ISee notel November 2008 Entergy/ANO-1 HL Decay Heat Nozzle 12 November 2008 Duke Energy Energy/Oconee-2 HL Decay Heat Nozzle 12 November 2008 FPL/St. Lucie-2 HL Surge Nozzle 12 HL Shutdown Cooling Nozzle 12 October 2008 APS/Palo Verde-I HL Shutdown Cooling Nozzles 16 October 2008 SCE/SONGS-3 HL Surge Nozzle 12 HL Shutdown Cooling Nozzle 16

_ _HL Drain Nozzle 2 May 2008 SCANA/V. C. Summer PZR Surge Nozzle 12 PZR Spray Nozzle 4 PZR Safety/Relief Nozzles 6 1

Enclosure (4)

Technical Basis for Proposed Alternatives to ASME Code Case N-638-1, Ambient Temperature Temperbead Welding Table 4.1 Dissimilar Metal Weld Overlay Experience Nozzle Date Plant Component Diameter (in)

[See notel May 2008 Entergy/Waterford-3 PZR Surge Nozzle 12 PZR Spray Nozzle 4 PZR Safety/Relief Nozzles 6 HL Drain 2 HL Surge 12 HL Shutdown Cooling 14 April 2008 APS/Palo Verde-2 PZR Surge Nozzle 12 PZR Spray Nozzle 4 PZR Safety/Relief Nozzles 6 HL Surge Nozzle 12 HL Shutdown Cooling Nozzle 16 April 2008 Duke Energy Energy/Oconee- I Decay Heat Nozzle 12 April 2008 Dominion/Millstone-2 Shutdown Cooling Nozzle 12 Safety Injection Nozzles 12 RCS Spray Nozzle 3.5 Charging Inlet Nozzles 2 April 2008 STPNOC/STP-1 PZR Surge Nozzle 16 PZR Spray Nozzle 6 PZR Safety/Relief Nozzles 6 March 2008 Entergy/ANO-2 HL Drain Nozzle 2 HL Shutdown Cooling Nozzle 14 HL Surge Nozzle 12 January 2008 FENOC/Davis-Besse PZR Surge Nozzle 10 PZR Spray Nozzle 4 PZR Safety/Relief Nozzles 2.5/3.0 HL Surge Nozzle 10 HL Decay Heat Nozzle 12 December 2007 SCE/SONGS 2 PZR surge nozzle 12 November 2007 Duke Energy/Oconee 3 PZR spray nozzle 4 safety/relief nozzles 4.5 PZR surge nozzle 10 November 2007 APS/Palo Verde 3 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 12 October 2007 SCE/SONGS 3 PZR surge nozzle 12 October 2007 Duke Energy/Catawba 1 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 14 October 2007 PSEG/Hope Creek Recirc Inlet nozzle 10 October 2007 TVA Sequoyah 1 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 12 October 2007 Tai Power/Kuosheng 2 Recirc Inlet nozzle 10 September 2007 Progress/Harris PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 14 2

Enclosure (4)

Technical Basis for Proposed Alternatives to ASME Code Case N-638-1, Ambient Temperature Temperbead Welding Table 4.1 Dissimilar Metal Weld Overlay Experience Nozzle Date Plant Component Diameter (in)

ISee notel June 2007 APS/Palo Verde 1 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 12 May 2007 Entergy/ANO 1 PZR spray nozzle 4 safety/relief nozzles 4.5 PZR surge nozzle 10 May 2007 Duke Energy/Oconee 2 PZR spray nozzle 4 safety/relief nozzles 4.5 PZR surge nozzle 10 April 2007 Duke Energy/McGuire 1 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 14 April 2007 STPNOC/South Texas 2 PZR spray nozzle 6 safety/relief nozzles 6 PZR surge nozzle 16 March 2007 FPL/Duane Arnold Recirc. Inlet nozzles 10 March 2007 TPC/Chin Shan Recirc Outlet nozzle 23 March 2007 Entergy/Pilgrim Recirc. Inlet nozzle 10 December 2006 TVA/Sequoyah 2 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 14 November 2006 SCE/SONGS Unit 3 PZR spray nozzle 5.1875 safety/relief nozzles 8 PZR surge nozzle 12.75 November 2006 Duke Energy/Catawba Unit 1 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 14 November 2006 Duke Energy/Oconee Unit 1 PZR spray nozzle 4.5 safety/relief nozzles 4.5 PZR surge nozzle 10.875 HL Surge Nozzle 10.75 October 2006 Duke Energy/McGuire Unit 2 PZR spray nozzle 4 safety/relief nozzles 6 PZR surge nozzle 14 April 2006 FENOC/Davis-Besse Hot leg drain nozzle 4 February 2006 SCE/SONGS Unit 2 PZR spray nozzle 8 safety/relief nozzles 6 November 2005 TPC/Kuosheng Unit 2 Recirculation outlet nozzle 22 April 2004 PPL/Susquehanna Unit 1 Recirc. inlet nozzle 12 Recirc. outlet nozzle 28 November 2003 AmerGen/TMI Unit 1 Surge line nozzle 11.5 October 2003 Entergy/Pilgrim Core spray nozzle 10 CRD return nozzle 5 October 2002 Exelon/Peach Bottom Units 2 and Core spray nozzle 10 3 Recirc. outlet nozzle 28 CRD return nozzle 5 October 2002 AmerGen/Oyster Creek Recirc. outlet nozzle 26 December 1999 FPL/Duane Arnold Recirc. inlet nozzle 12 3

Enclosure (4)

Technical Basis for Proposed Alternatives to ASME Code Case N-638-1, Ambient Temperature Temperbead Welding Table 4.1 Dissimilar Metal Weld Overlay Experience Nozzle Date Plant Component Diameter (in)

[See note]

June 1999 FENOC/Perry Feedwater nozzle 12 June 1998 CEG/Nine Mile Point Unit 2 Feedwater nozzle 12 March 1996 Progress/Brunswick Units 1 and 2 Feedwater nozzle 12 February 1996 Southern/Hatch Unit I Recirc. inlet nozzle 12 January 1991 Entergy/River Bend Feedwater nozzle 12 March 1986 Entergy/Vermont Yankee Core spray nozzle 10 Note: The total area of overlay on the low alloy steel varies widely from about 16 square inches on the smaller diameter nozzles such as drain nozzles to about 325 square inches on the larger diameter components such as recirculation outlet nozzles.

It can be seen from the information above that the original DMW weld overlay was applied over 20 years ago, and weld overlays with low alloy steel coverage in the 100-square inch range have been in service for 5 to 15 years. Several overlays have been applied with low alloy steel coverage significantly greater than the 100 square inches. These overlays have been examined with Performance Demonstration Initiative qualified techniques, in some cases multiple times, and none have shown any signs of new cracking or growth of existing cracks.

2. Clarification of Charpy V-Notch Acceptance Criteria Paragraph 2.1(j) of Code Case N-638-1 states, "The average of the three HAZ impact tests shall be equal to or greater than the average values of the three unaffected base metal tests." However, the Charpy V-notch test acceptance criteria in Code Case N-638-1 is misleading and inconsistent with the specified acceptance criteria in Section XI applicable to other Class 1 components, since it implies that all three parameters - lateral expansion, absorbed energy, and percent shear fracture - must be equal to or exceed the base material values.

Code Case N-638-2 corrected paragraph 2.10) to state that Charpy V-notch acceptance criteria is based on the average lateral expansion values rather than the average of all three values. This change clarified the intent of the code case and aligned its Charpy V-notch acceptance criteria with that of Sections III and XI as demonstrated in the Code references provided below.

" ASME Section III - NB-4330, Impact Test Requirements

" ASME Section XI - IWA-4620, Temperbead Welding of SimilarMaterials

" ASME Section XI- IWA-4630, Temperbead Welding of DissimilarMaterials The Enclosure 2 acceptance criteria for Charpy V-notch testing of the weld HAZ is as specified in Code Case N-638-2. The ASME Section XI basis for this change is documented in the White Paper in ASME C&S Connect for Code Case N-638-2.

2. REFERENCE

1. EPRI Report 1011898, "RRAC Code Justification for the Removal of the 100 Square Inch Temperbead Weld Limitation," November 2005 4

ENCLOSURE (5)

Comparison of ASME Section XI Appendix VIII, Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay Calvert Cliffs Nuclear Power Plant, LLC May 18, 2010

Enclosure (5)

Comparison of ASME Section XI Appendix VIU, Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay Appendix VIII Suppleinentii Qualification Requirements for Full PDIProgram:

Structural .OverlaidWrought AusteniticPipingWelds .The Proposed Alternative to Supplement 11 Requirementis 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 having different Alternative: (b) The specimen set shall include specimens with overlays not nominal pipe diameters and overlay thicknesses. They shall include the thicker than 0.1 inch more than the minimum thickness, nor thinner than 0.25 inch minimum and maximum nominal pipe diameters for which the examination of the maximum nominal overlay thickness for which the examination procedure is procedure is applicable. Pipe diameters within a range of 0.9 to 1.5 times a applicable.

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

(d) Flaw Conditions (1) Base metalflaws. All flaws must be cracks in or near the butt weld heat Alternative: (1) Base metalflaws. All flaws must be in or near the butt weld heat affected zone, open to the inside surface, and extending at least 75% through the affected zone, open to the inside surface, and extending at least 75% through the base metal wall. Flaws may extend 100% through the base metal and into the base metal wall. Intentional overlay fabrication flaws shall not interfere with overlay material; in this case, intentional overlay fabrication flaws shall not ultrasonic detection or characterization of the base metal flaws. Specimens interfere with ultrasonic detection or characterization of the cracking. containing intergranular stress corrosion cracking shall be used when available. At Specimens containing intergranular stress corrosion cracking shall be used when least 70% of the flaws in the detection and sizing tests shall be cracks and the available. remainder shall be alternative flaws. Alternative flaw mechanisms, if used, shall 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 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 inch.

Basis: This paragraph requires that all base metal flaws be cracks and to extend at least 75% through the base metal wall. 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 1

Enclosure (5)

Comparison of ASME Section XI Appendix VIII, Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay Appendix VIII Supplement 11: Qualification Requirements for Full PDI Program:

.Structural Overlaid WroughtAustenitic Piping Welds The ProposedAlternative to Supplement 11 Requirements, 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 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 within +200 of Alternative: (1) At least 20% but less than 40% of the base metal flaws shall be the pipe axial direction. The remainder shall be oriented circumferentially. oriented within +200 of the pipe axial direction. The remainder shall be oriented Flaws shall not be open to any surface to which the candidate has physical or circumferentially. Flaws shall not be open to any surface to which the candidate has visual access. The rules of IWA-3300 shall be used to determine whether physical or visual access.

closely spaced flaws should be treated as single or multiple flaws. Basis: The requirement for axially oriented overlay fabrication flaws was excluded from the PDI Program as an improbable scenario. Weld overlays are typically applied using automated gas tungsten arc welding 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 units. Each Alternative: (2) Specimens shall be divided into base metal and overlay specimen shall contain one or both types of grading units. fabrication 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.

Basis: Inclusion of "metal" and "fabrication" provides clarification. Flaw identification is improved by ensuring flaws are not masked by other flaws.

(a)(1) A base grading unit shall include at least 3 in. of the length of the Alternative: (a)(1) A base metal grading unit includes the overlay material and the overlaid weld. The base grading unit includes the outer 25% of the overlaid outer 25% of the original overlaid weld. The base metal grading unit shall extend weld and base metal on both sides. The base grading unit shall not include the circumferentially for at least 1 inch and shall start at the weld centerline and be wide inner 75% of the overlaid weld and base metal overlay material, or base metal- enough in the axial direction to encompass one half of the original weld crown and a to-overlay interface, minimum of 0.50 inch of the adjacent 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 2

Enclosure (5)

Comparison of ASME Section XI Appendix VIII, Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay Appendix VII Supplement 11: Qualification Requirements for Full PDT Program:

.Structural Overlaid Wrought Austenitic Piping Welds. The Proposed Alternative to Supplement 11 Requirements.

sides of the weld. This paragraph was also modified to require that a base metal grading unit include at least 1 inch of the length of the overlaid weld, rather than 3 inches.

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

grading unit. Basis: Substituted terms provide clarification and are consistent with ld(1) above.

The PDI program adjusts for this conservative change for excluding this type grading unit.

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

grading unit. The segment of weld length used in one base grading unit shall Basis: This paragraph was modified to require sufficient unflawed overlaid weld not be used in another base grading unit. Base grading units need not be and base metal to exist on all sides of the grading unit to preclude interfering uniformly spaced around the specimen. reflections from adjacent flaws, rather than the 1 inch requirement.

(b)(1) An overlay grading unit shall include the overlay material and the base Alternative: (b)(1) An overlay fabrication grading unit shall include the overlay metal-to-overlay interface of at least 6 square inch. The overlay grading unit material and the base metal-to-overlay interface for a length of at least 1 inch.

shall be rectangular, with minimum dimensions of 2 inches. Basis: The PDI program reduces the base metal-to-overlay interface to at least 1 inch (in lieu of a minimum of 2 inches) and eliminates the minimum rectangular dimension. This criterion is necessary to allow use of existing examination specimens that were fabricated in order to meet Nuclear Regulatory Commission Generic Letter 88-01. This criterion may be more challenging than the American Society of Mechanical Engineers Code because of the variability associated with the shape of the grading unit.

(b)(2) An overlay grading unit designed to be unflawed shall be surrounded by Alternative: (b)(2) Overlay fabrication grading-units designed to be unflawed shall unflawed overlay material and unflawed base metal-to-overlay interface for at be separated by unflawed overlay material and unflawed base metal-to-overlay least 1 in. around its entire perimeter. The specific area used in one overlay interface for at least 1 in. at both ends. Sufficient unflawed overlaid weld and base grading unit shall not be used in another overlay grading unit. Overlay grading metal shall exist on both sides of the overlay fabrication grading unit to preclude units need not be spaced uniformly about the specimen, interfering reflections from adjacent flaws. The 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: This paragraph 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 1 inch at both ends, rather than around its entire 3

Enclosure (5)

Comparison of ASME Section XI Appendix VIII, Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay Appendix VHIISupplement 11: Qualification Requirements forFull PDI Program:-

' Structural

. Overlaid Wrought AusteniticPiping Welds The Proposed Alternative to Supplement 11 Requirements perimeter.

(b)(3) Detection sets shall be selected from Table VIII-S2-1. The minimum Alternative: ('b)(3) Detection sets shall be selected from Table VIII-S2-1. The detection sample set is five flawed base grading units, ten unflawed base minimum detection sample set is five flawed base metal grading units, ten unflawed grading units, five flawed overlay grading units, and ten unflawed overlay base metal grading units, five flawed overlay fabrication grading units, and ten grading units. For each type of grading unit, the set shall contain at least twice unflawed overlay fabrication grading units. For each type of grading unit, the set as many unflawed as flawed grading units. shall contain at least twice as many unflawed as flawed grading units. For initial procedure 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.

Basis: Clarified the guidance for initial procedure qualifications versus qualifying new values of essential variables.

69 Sizing Specimen (1) The minimum number of flaws shall be ten. At least 30% of the flaws shall Alternative: (1) The minimum number of flaws shall be ten. At least 30% of the be overlay fabrication flaws. At least 40% of the flaws shall be cracks open to flaws shall be overlay fabrication flaws. At least 40% of the flaws shall be open to the inside surface. the inside surface. Sizing sets shall contain a distribution of 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.

Basis: Clarified the guidance for initial procedure qualifications versus qualifying new values of essential variables and is consistent with 1.1 (d)(1) above.

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

Basis: Clarified wording to be consistent with 1.1 (d)(1) above.

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

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

2.0 CONDUCT OF PERFORMANCE DEMONSTRATION The specimen inside surface and identification shall be concealed from the The specimen inside surface and identification shall be concealed from the candidate. All examinations shall be completed prior to grading the results and candidate. All examinations shall be completed prior to grading the results and presenting the results to the candidate. Divulgence of particular specimen presenting the results to the candidate. Divulgence of particular specimen results or results or candidate viewing of unmasked specimens after the performance candidate viewing of unmasked specimens after the performance demonstration is 4

Enclosure (5)

Comparison of ASME Section XI Appendix VIII, Supplement 11 to Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay

'Appendix VIII Supplement ll: Qualification Requirements for Full PDI Program:

- Structural Overlaid Wrought Austenitic Piping Welds. The Proposed Alternative toSupplement 11 Requirements demonstration is prohibited. prohibited. The overlay fabrication flaw test and the base metal flaw test may be performed separately.

Basis: The PDI Program revised paragraph 2.0 allowing the overlay fabrication and base metal flaw tests to be performed separately.

2.1 Detection Test Flawed and unflawed grading units shall be randomly mixed. Although the Alternative: Flawed and unflawed grading units shall be randomly mixed.

boundaries of specific grading units shall not be revealed to the candidate, the Although the boundaries of specific grading units shall not be revealed to the candidate shall be made aware of the type or types of grading units (base or candidate, the candidate shall be made aware of the type or types of grading units overlay) that are present for each specimen. (base metal or overlay fabrication) that are present for each specimen.

Basis: Clarified wording similar to l(e)2 above.

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

Basis: Clarified wording for consistency and to be consistent with 1.l(d)(1) above.

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

flaws, the regions of each specimen containing a flaw to be sized shall be (b) When the depth sizing test is conducted in conjunction with the detection test identified to the candidate. The candidate shall determine the maximum depth and the detected flaws do not satisfy the requirements of 1.1 (f), additional specimens of the flaw in each region. shall 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 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 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 qualified for detection Alternative: Examination procedures are qualified for detection when:

when the results of the performance demonstration satisfy the acceptance (1) All flaws within the scope of the procedure are detected and the results of the 5

Enclosure (5)

Comparison of ASME Section XI Appendix VIII, Supplement 1lto Performance Demonstration Initiative (PDI) for Full Structural Weld Overlay Appendix VHi Supplement 11: Qualification Requirements for Full PDI Program:

",Structural Overlaid Wrought Austenitic Piping Welds.-. The Proposed Alternativeto Supplement 1! Requirements criteria of Table VIII-S2-1 for both detection and false calls. The criteria shall performance demonstration satisfy the acceptance criteria of Table VIII-S2-1 for be satisfied separately by the demonstration results for base grading units and false calls.

for overlay grading units. (2) At least one successful personnel demonstration has been performed meeting the acceptance criteria defined in (3b).

(3) 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.

(4) The criteria in (2), (3) shall be satisfied separately by the demonstration results for base metal grading units and for overlay fabrication grading units.

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

3.2 Sizing Acceptance Criteria (a) The root mean square (RMS) error of the flaw length measurements, as Alternative: (a) The RMS error of the flaw length measurements, as compared to compared to the true flaw lengths, is less than or equal to 0.75 inch. The length the true flaw lengths, is less than or equal to 0.75 inch. The length of base metal of base metal cracking is measured at the 75% through-base-metal position. flaws is measured at the 75% through-base-metal position.

Basis: Clarified wording to be consistent with 1.l(d)(1) above.

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

0.1 inch. are reported as being intrusions into the overlay material. Basis: The requirement for reporting all extensions of cracking 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 sizing criteria.

6