Text

Supplement to Request for Use of Structural Weld Overlays as an Alternative Repair Technique
	ML080500146
Person / Time
Site:	Seabrook
Issue date:	02/13/2008
From:	St.Pierre G; Florida Power & Light Energy Seabrook
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	SBK-L-08022
	Download: ML080500146 (41)
	v • d • e

0FPL Energy Seabrook Station FPL Energy RO. Box 300 Seabrook, NH 03874 Seabrook Station (603) 773-7000 February 13, 2008 Docket No. 50-443 SBK-L-08022 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Seabrook Station Supplement to Request for Use of Structural Weld Overlays as an Alternative Repair Technique

References:

1.

FPL Energy Seabrook, LLC (FPL Energy Seabrook) letter SBK-L-07120, Request for Use of Structural Weld Overlays as an Alternative Repair Technique, July 3, 2007.

Pursuant to 10 CFR 50.55a(a)(3)(i), FPL Energy Seabrook, LLC (FPL Energy Seabrook) requested approval to use the American Society of Mechanical Engineers (ASME) Code Case N-740-1, "Dissimilar Metal Weld Overlay for Repair of Class 1, 2, and 3 ItemsSection XI, Division 1," draft May 2007, to apply dissimilar metal weld overlays for repair/replacement activities (Reference 1).

The request contained alternative requirements for the inservice inspection (ISI) program for structural weld overlays (SWOLs) that are planned to mitigate the potential for primary water stress corrosion cracking (PWSCC) susceptibility at Seabrook Station Unit 1.

Subsequent to the submittal, FPL Energy Seabrook determined that it was prudent to supplement the previous submittal with an additional information regarding the application of the SWOLs. contains FPL Energy Seabrook's Alternative Request and to Attachment 1 contains the Performance Demonstration Initiative (PDI)

Program Modifications to American Society of Mechanical Engineers (ASME) Code, Appendix VIII, Supplement 11. Enclosure 2 provides the "Alternative Requirements for Dissimilar Metal Weld Overlays" and Enclosure 3 is entitled, "Barrier Layer to Prevent Hot Cracking in High Sulfur Stainless Steel."

This is the initial phase of the control and remediation plan for Alloy 600/82/182 dissimilar metal piping butt welds susceptible to potential PWSCC at Seabrook Unit 1, and SWOLs for mitigation of potential PWSCC susceptible areas are scheduled for the A4c07 A411 an FPL Group company

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 2 cycle 12 refueling outage and no pre-weld overlay UT examinations are planned. FPL Energy Seabrook will use the alternatives in this request to implement the Electric Power Research Institute's Materials Reliability Program (EPRI/MRP) and the Primary System Piping Butt Weld Inspection and Evaluation Guideline (MRP-139) under the ISI program and the risk-infomaed ISI (RI-ISI) program.

FPL Energy Seabrook requests review and approval of this proposal be expedited to support the Seabrook Unit 1 refueling outage scheduled to begin in April of 2008.

Similar alternatives have been submitted for NRC review and approval and are referenced in the attached request. Details of the design analysis for the planned weld overlays are being developed to support the Seabrook Unit 1 2008 refueling outage. The analysis will be available at Seabrook Station for NRC review at the beginning of OR12.

If you have any questions regarding this submittal, please contact Mr. James M. Peschel, Regulatory Programs Manager, at (603) 773-7194.

Very truly yours, FPL Energy Seabrook, LLC Gene St. Pierre Site Vice President cc:

S. J. Collins, NRC Region I Administrator G. E. Miller, NRC Project Manager W. J. Raymond, NRC Resident Inspector to SBK-L-08022

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 1 ATTACHMENT 1 10 CFR 50.55a REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(i)

USE OF WELD OVERLAYS AS AN ALTERNATIVE REPAIR TECHNIQUE

1.0 ASME Code Components Affected

Code components associated with this request are high safety significant (HSS) Class 1 dissimilar metal welds (DMWs) with Alloy 82/182 weld metal in the pressurizer that are believed to be susceptible to Primary Water Stress Corrosion Cracking (PWSCC). There are six (6) welds that are scheduled to have preemptive full structural weld overlays (SWOLs) applied.

In addition the SWOLs will extend across the six (6) adjacent stainless steel pipe-to-safe end similar metal welds. These welds are scheduled to have SWOLs applied during refueling outage 12 (OR12) that is currently scheduled to commence in April 2008.

1.1 Category and System Details:

Code Class:

Class 1 System Welds:

Reactor Coolant System Examination Categories:

R-A*

Welds are included in the Risk Informed Inservice Inspection Program 1.2 Component Descriptions:

The application of this alternative to apply SWOLs on one (1) potentially PWSCC susceptible safe end-to-pressurizer surge nozzle DMW, three (3) safe end-to safety nozzle DMWs, one (1) safe end-to-relief nozzle DMW and one (1) safe end-to-spray nozzle DMW. The SWOLs will extend outward across the adjacent stainless steel pipe-to-safe end welds. The applicable weld identifications are shown in Table 1. The general configuration for the different nozzle locations is shown in Figure 1.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 2 TABLE 1 WELD NUMBERS B Y ISI DESIGNA TION Weld Number by ISI Desinatio Safe End to Nozzle Pipe to Safe End ItemLocaionSafe End to Nozzle Pipe to Safe End Item LocationWeded Weld Weld 1

Pressurizer Spray Nozzle RC E-10 SP-SE RC 0048-03 06 2

Pressurizer Relief Nozzle B RC E-10 B-SE RC 0080-01 01 3

Pressurizer Safety Nozzle A RC E-10 A-SE RC 0074-01 01 4

Pressurizer Safety Nozzle C RC E-10 C-SE RC 0075-01 01 5

Pressurizer Safety Nozzle D RC E-10 D-SE RC 0076-01 01 6

Pressurizer Surge Nozzle RC E-10 S-SE RC 0049-01 05 1.3 Component Materials:

The applicable materials are depicted in Table 2. There are no cast stainless steel materials.

TABLE 2 MATERIALS Nozzle Nozzle Safe End (P-No. 3 Buttering to(P-No. 8 Pipe to Safe Pipe Location Buttering End Weld (P-No. 8 Group (F-No. 43)

Weld(A-No.

8)

Group 1)

3)

WeldoGroupr1)pEn SA-508 Alloy 182 Alloy SA-182 SA-376 Spray Cl 2a 82/182 GR F316L ER308/E308 TP316 Safety &

SA-508 Alloy 182 Alloy SA-182 ER308/E308 SA-376 SafeC&

2a Alloy GR F316L with ER308L Relief 82/182 TP316 Root Insert SA-508 Alloy 182 Alloy SA-182 SA-376 Surge Cl 2a 82/182 GR F316L ER308/E308 TP304

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 3 2.0

Applicable Code Edition and Addenda

Seabrook Station is currently in the 2 nd 10-year Inservice Inspection (ISI) interval. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) of record for the current 10-year ISI interval isSection XI, 1995 Edition, including Addenda through 1996 (Reference 1) for the Repair/Replacement Program.

3.0

Applicable Code Requirement

The applicable Code requirement for which the relief is requested is ASME Code Section XI, 1995 Edition including Addenda through 1996 (Reference 1), IWA-4410, IWA-4611 and Appendix VIII, Supplement 11.

IWA-4410(a) states:

"Repair/replacement activities shall be performed in accordance with the Owner's Requirements and the original Construction Code of the component or system, except as provided in IWA-4410(b), (c), and (d)."

IWA-4410(c) states in part the following:

"Alternatively, the applicable requirements of IWA-4600 may be used for welding....."

IWA-46 11.1 (a) states in part the following:

"Defects shall be removed or reduced in size in accordance with this Paragraph."

IWA-461 1.1 (b) states:

The original defect shall be removed:

IWA-461 1.1 (b)(2) states:

"when welding is required in accordance with IWA-4630 or IWA-4640 and the defect penetrates the base material."

IWA-4611.4(a) states in part the following:

"After final grinding, the affected surfaces, including surfaces of cavities prepared for welding, shall be examined by the magnetic particle or liquid penetrant method to ensure that the indication has been reduced to an acceptable size in accordance with IWA-3000...."

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 4 Appendix VIII provides requirements for performance demonstration for ultrasonic examination systems.

Supplement 11 provides qualification requirements for full structural overlaid wrought austenitic piping welds.

4.0

Reason for Request

DMWs, primarily consisting of Alloy 82/182 weld metal are frequently used in pressurized water reactor (PWR) construction to connect stainless steel pipe and safe ends to vessel and pipe nozzles that are typically constructed of carbon or low alloy ferritic steel. These welds have shown a tendency for PWSCC degradation, especially in components subjected to higher operating temperatures, such as the pressurizer.

See EPRI MRP-169 "Technical basis for Preemptive Weld Overlays for Alloy 82/182 Butt Welds in PWRs", October 2005 (Reference 2).

During OR12, six (6) DMWs located on the pressurizer are scheduled to have SWOLs applied. ASME Code Section XI, 1995 Edition, including Addenda through 1996 (Reference 1), IWA-4410 and IWA-46 11, does not provide all the needed requirements for this type of repair since potential existing defects will not be removed or reduced in size and weld overlay of potential existing flaws in DMWs will be performed. In addition, ASME Code Section XI, 1995 Edition, including Addenda through 1996 (Reference 1), Appendix VIII, Supplement 11 cannot be implemented as written for ultrasonic examination of a structural weld overlay repair. includes a discussion of the Performance Demonstration Initiative (PDI) Program alternatives and their bases with respect to Appendix VIII, Supplement 11 requirements. Comprehensive and generic NRC approved criteria are not currently available for application of SWOL repairs to DMWs constructed of Alloy 82/182 weld material for mitigation of potential PWSCC.

The alternative described in Section 5.0 is proposed to permit the implementation of SWOLs at Seabrook Station, as an alternative for the repair and replacement requirements of the ASME Code Section XI, 1995 Edition including Addenda through 1996 (Reference 1), IWA-4410, IWA-46 11 and Appendix VIII, Supplement 11.

5.0 Proposed Alternative And Basis for Use This proposal requests the use of the Alternative Requirements shown in Enclosure 2 for implementing the six (6) scheduled SWOLs for potentially PWSCC susceptible safe end-to-nozzle welds of the pressurizer.

These SWOLs will include the six (6) adjacent stainless steel pipe-to-safe end welds. This request applies to each of the welds listed in Section 1.2, which are generically depicted in Figure 1. The proposed Alternative is scheduled to be performed during the Seabrook Station Spring 2008 refueling outage.

This proposed alternative (Enclosure 2) is the result of industry's experience with weld overlay modifications for flaws suspected or confirmed to be caused by PWSCC and

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 5 directly applies to the Alloy 52 or 52M weld material that is primarily being used for these SWOL's.

The ultrasonic examination of the completed SWOLs will be accomplished using personnel and procedures qualified in accordance with ASME Code Section XI, 1995 Edition, including Addenda through 1996 (Reference 1), Appendix VIII, Supplement 11 (as specified in Enclosure 2, Section 3 therein), with the alternatives used for complying with the PDI Program. See Enclosure 1 for the PDI Program changes to Appendix VIII, Supplement 11.

5.1 SWOL Design The SWOLs satisfy all the structural design requirements of the pipe as specified in the Alternative Requirements shown in Enclosure 2 for the original safe end-to-nozzle welds and the pipe -to-safe end welds. As shown in Figure 1, the SWOLs will completely cover the existing Alloy 82/182 weld and will extend onto the ferritic nozzle and austenitic stainless steel material on each end of the weld, including the adjacent pipe -to-safe end weld. The SWOL's extend around the entire circumference of the nozzle. Alloy 52M and 52 filler metals are compatible with all the wrought materials and the DMW and similar metal welds that will be covered by the SWOL.

The SWOLs will be designed as full structural overlays. Postulated 100% through wall flaws shall be assumed as specified in 2(b)(3), Enclosure 2, for SWOL length and thickness sizing as specified in 2(b)(4) Enclosure 2. No ultrasonic examination will be performed prior to SWOL application. For flaw growth evaluations, since no ultrasonic examination will be performed prior to SWOL application, postulated 75% through wall flaws will be assumed as specified in 2(a)(2) and 2(a)(2)(a), Enclosure 2, for the welds on all nozzle locations where SWOLs will be applied. Planar flaws detected during the acceptance examination will be characterized and flaw growth calculations performed using the flaw(s) detected plus the postulated 75% through wall flaws.

Note that the details surrounding the design analysis for the SWOLs are being developed to support the Seabrook Station Spring 2008 refueling outage (OR12) and our vendor has committed to supplying this analysis to FPL. The analysis will be available at the plant for NRC review at the beginning of the OR12 refuel outage.

Paragraph 3(a)(3) of Enclosure 2 states that "for planar indications outside this examination volume, the nominal wall thickness shall be "t2" as shown in Fig 1(c) for volumes A-E-H-D and F-B-C-G." Initial 100% through wall axial and circumferential flaws are assumed for SWOL design and 75% through wall axial and circumferential flaws are assumed for flaw growth evaluations at all nozzle locations where SWOLs will be installed. "t 2" is V2 in. outside the PWSCC susceptible DMW. The portion of the pipe, safe end or nozzle material outside the PWSCC susceptible material is assumed unflawed. These volumes are also outside any other Section XI ISI volume other than associated with the original weld ISI as shown in Figure IWB-2500-8(c) so service

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 6 related flaws therein are not expected to occur. Surface examination is also performed on these areas before the SWOLs are applied to verify absence of surface flaws. The volume of the overlay which is more than 1/2 inch from the susceptible region is treated as a cross section which is the SWOL thickness plus the original underlying base metal wall thickness. The acceptance standard for a flaw in the SWOL from Table IWB-3514-2 is thus based on" t2". The approach is consistent with other examinations in Section XI including pipe to pipe welds where the examination volume does not include the entire thickness but the acceptance criteria does. Furthermore indications in the overlay will be required to be sized. This requirement will assure that the indications which may extend into the base metal are not excluded.

5.2 Welding The welding will be performed in accordance with Enclosure 2 using a remote machine gas tungsten-arc welding (GTAW) process and using the ambient temperature temper bead method with ERNiCrFe-7A (Alloy 52M) weld metal.

Manual GTAW, using ERNiCrFe-7 (Alloy 52) or Alloy 52M will be used if local repairs of weld defects are necessary or additional weld metal is required locally to form the final SWOL contour in locations at least 3/16 in. away from the low alloy steel nozzles.

During recent DMW overlay activities, where use of ERNiCrFe-7A (Alloy 52M) and ERNiCrFe-7 (Alloy 52) has been used for the filler metal, flaws in the first layer have occurred in the portion of the overlay deposited on the austenitic stainless steel portions (safe ends, pipe etc.) of the assemblies in some cases.

The flaw characteristics observed above are indicative of hot cracking. This phenomenon has not been observed on the ferritic steel or ENiCrFe-3 (Alloy 182) DMW portions of the assemblies when welding Alloy 52M thereon.

Further studies have determined that this problem may occur when using Alloy 52M filler metal on austenitic stainless steel materials with high sulfur content.

Limited tests and evaluations recently performed by AREVA have resulted in the conclusion that welding with Alloy 52M on stainless steel base material with 0.020 wt%

sulfur results in cracking while welding on stainless steel base materials with less than 0.010 wt% have resulted in no cracking.

Seabrook Station will use the barrier layer on all the stainless steel items prior to overlay.

The barrier layer will use ER309L on the stainless steel and Alloy 82 on the stainless steel near the DMW to stainless steel fusion zone only.

The barrier layer will not be used in the structural analysis or in the crack growth analysis. The inside diameter of the portion of the SWOL over the barrier layer will be the outside diameter of the barrier layer that is applied over the stainless steel material beneath the SWOL. See Enclosure 3 for more information.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 7 The Cr content of the 1s' layer was verified by weld deposition on an A-106 Grade B pipe mockup using double uIp progression (starting at bottom and welding upward to top on each side). Welding was performed in the 6G position with Cr measured at 90 degree increments starting at 45 degrees from top. All welding parameters were recorded and the 24% minimum Cr value specified in 1 (e), Enclosure 2, was attained. The same heat of wire, or wire heat with equal or greater Cr content than that used in qualification, will be used in situ for the first layer. The same welding parameters will be specified in the WPS as was used in the mockup for the portion of the first layer extending over the austenitic base material, austenitic filler material weld and the associated dilution zone from the adjacent ferritic steel nozzle base material at the edge of the DMW, as specified in paragraph 1.0(e), Enclosure 2.

The SWOL will require welding on more than 100 square inches of surface on the pressurizer surge nozzle low alloy steel base material but less than 300 square inches which is permitted in Appendix I, I-l(b), Enclosure 2. The SWOL will extend toward the pressurizer onto the ferritic steel nozzle base material for a sufficient length so that qualified ultrasonic examination of the required volume can be performed after the SWOL is applied.

There have been a number of temper bead SWOLs applied to safe-end to nozzle welds in the nuclear industry, and SWOLs having more than 100 square inch surface area on the nozzle ferritic steel surfaces have been used. The ASME Committee has indicated the inside diameter compressive stress levels remain essentially the same for both 100 square inches and 500 square inches related to SWOL applications. The justification entitled "Bases for 500 Sq. In. Weld Overlay Over Ferritic Material", was provided to the NRC staff in the January 10, 2007 meeting (Accession No. ML070470565).

Additional justification is provided in Appendix F of EPRI Report 1014351, Repair and Replacement Applications Center: Topical Report Supporting Expedited NRC Review of Code Cases for Dissimilar Metal Weld Overlay Repairs" July 2006 (Reference 4).

The thickness of the SWOLs may exceed '/2 the carbon and low alloy ferritic steel nozzle base metal thickness as specified in Code Case N-638-1. The requirement therein applies to excavated cavities in the ferritic steel base material that are subsequently welded flush.

This requirement is not applicable to SWOLs since they are applied to the nozzle surface and limited to 3/8 in. depth into the ferritic steel as specified in Enclosure 2, Appendix I, 1-1(d). Additional justification is provided in Appendix F of Reference 4.

1-3.0(d), Appendix I, Enclosure 2, specifies the maximum interpass temperature shall be limited to 350F maximum, even though the maximum interpass temperature is limited to 150F maximum for the first three layers in the test assembly specified in 1-2.1(c). This is greater than the maximum 100F interpass temperature increase permitted by QW-406.3.

The following is a clarification of the intent of Code Case N-638-1 that has been included in Code Case N-638-2. The limitation on the procedure qualification maximum interpass temperature(150F) is to ensure the cooling rates achieved during procedure qualification

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 8 are more severe than those encountered during field welding (are not slower than those achievable during field welding). The higher interpass temperature is permitted during field welding because it would only result in slower cooling rates which could be helpful in producing more ductile transformation products in the ferritic steel heat affected zone (HAZ). Additional justification information is also included in Appendix D, Reference 4.

5.3 Examination Appendix VIII Supplement 10 ultrasonic examination will not be performed on the DMWs prior to the SWOLs being applied. Since the structural integrity at the DMW locations will be restored by the SWOLs the ultrasonic examination of the DMWs prior to SWOL application is unnecessary and the increased personnel dose that would be incurred performing the examinations is also undesirable and not consistent with good ALARA practice. All welds have postulated 100% through wall cracks for the SWOL design and postulated 75% through wall cracks for the flaw growth evaluations.

The ultrasonic and surface examinations will be performed on the temper bead portion of the SWOLs no sooner than 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months after completion of the third temper bead layer as specified in 3(a)(2) and 3(a)(3), Enclosure 2.

The 48 hour5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months delay is intended to provide time for delayed hydrogen cracking occurrence., Appendix 1 requires the machine or automatic GTAW process to be used for temper bead welding thereby eliminating the use of welding processes requiring flux for arc shielding.

The machine GTAW temper bead process uses a welding process that is inherently free of hydrogen. The GTAW process relies on bare welding electrodes and bare wire filler metal with no flux to absorb moisture. An inert gas blanket provides shielding for the weld and surrounding metal, which protects the region during welding from the atmosphere and the moisture it may contain and typically produces porosity free welds.

In accordance with the weld procedure qualification, welding grade argon is used for the inert gas blanket. To further reduce the likelihood of any hydrogen effects, specific controls will be used to ensure the welding electrodes, filler metal and weld region are free of all sources of hydrogen.

In addition, the use of the machine GTAW temper bead process provides precise control of heat input, bead placement, bead size and contour. The very precise control over these factors afforded by the machine GTAW process provides effective tempering of the nozzle ferritic steel HAZ resulting in achievement of lower hardness and tempered martensite. This further reduces susceptibility to hydrogen induced cracking.

EPRI Report 1013558, Temperbead Welding Applications, 48 Hour Hold Requirements for Ambient Temperature Temperbead Welding, Technical Update, December 2006 (Reference 3) provides justification for reducing the 48 hour5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months hold time on P-No. 3 Group No. 3 ferritic steel base material to start after completion of the third temper bead layer, as specified in Enclosure 2. Report 1013558 addresses microstructural issues, hydrogen

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 9 sources, tensile stress and temperature, and diffusivity and solubility of hydrogen in steels.

Past industry experience with the use of the machine or automatic GTAW process has resulted in no detection of hydrogen induced cracking after the 48 hour5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months hold nondestructive examination (NDE) or subsequent in-service inspections.

Code Case N-638-4, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique Section XI Division 1," specifies NDE to be performed on the final weld no sooner than 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months after completion of the third temper bead layer.

All examinations will meet the requirements of Enclosure 2, excluding qualification of the ultrasonic examination for the completed SWOLs.

The ultrasonic examination qualification will be in accordance with ASME Code Section XI, 1995 Edition including Addenda through 1996 (Reference 1), Appendix VIII, Supplement 11 with the alternatives that are used to comply with the PDI Program. See Enclosure 1 for the PDI Program changes to Appendix VIII Supplement 11.

Inservice inspection will be performed as specified in Enclosure 2 with the exceptions that the ultrasonic examination procedures and personnel will be qualified in accordance Appendix VIII, Supplement 11 as modified by the PDI Program as specified in Enclosure 1.

The final ultrasonic examination report will be submitted to the NRC within 60 days after completion thereof. Any flaws detected that exceed the acceptance standards of Table IWB-3514-2 will be reported to the NRC as soon as possible. A discussion and reason for any SWOL or base metal repairs will be provided.

The ultrasonic examination requirements specified in NRC Regulatory Guide 1.147 Revision 14 as conditional acceptance of Code Case N-638-1 are not applicable to SWOLs. Ultrasonic examination (UT) of the SWOLs will be performed in accordance with Section XI, Appendix VIII, Supplement 11 qualified procedures and personnel as modified by PDI. The PDI modifications are shown in Enclosure 1. Supplement 11 was prepared to be specifically applicable to weld overlays. The ultrasonic examination requirements in Section 3, Enclosure 2, are similar to the ultrasonic examination requirements provided in Appendix Q which have been developed specifically for austenitic weld overlays.

The UT to be performed, in conjunction with the surface examinations to be performed, as specified in Section 3 Enclosure 2 are based on the latest industry experience and practice and completely satisfactory for the SWOL application.

The uninspectable volume noted in 3(a)(3)(c), Enclosure 2, is defined in 3(a)(3)(b) as the volume in the weld overlay underneath the laminar flaw(s) for which coverage cannot be achieved using the angle beam examination method. It is the hypothetical volume that is created by the angle beam shadow from the laminar flaw.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 10 Flaws in the SWOL that do not comply with the preservice examination acceptance standards of Table IWB-3514-2 will be removed.

5.4 Conclusion The proposed alternative shown in Enclosure 2 has been developed to cover the most recent operating experience and NRC approved criteria that are associated with similar SWOL applications.

Similar NRC approved requests have been used to produce acceptable weld overlays when applied to DMWs with Alloy 82/182 weld material.

Therefore FPL considers that Enclosure 2 and the PDI Program provides an acceptable level of quality and safety, consistent with provisions of 10 CFR 50.55a(a)(3)(i).

6.0 Precedents Similar requests have been submitted to address the issues that are contained in this request.

These include requests from the Indiana Michigan Power Company's, D. C. Cook Unit 2.

NRC verbal approval was received on March 23, 2006, for their request, which included the application of full structural weld overlays applied to their pressurizer nozzle DMWs.

In a letter dated, March 13, 2007, a similar request was submitted for North Anna Units 1 and 2 by Virginia Electric and Power Company (Dominion). NRC verbal approval was received March 29, 2007 and final NRC approval was documented and provided in December 2007.

Additionally, the following requests associated with weld overlay repairs have been approved by the NRC: AmerGen Energy Company, Three Mile Island Nuclear Station, Unit 1, on July 21, 2004;(l) Constellation Energy's Calvert Cliffs Nuclear Power Plant, Unit 2, on July 20, 2005;(2) Millstone Unit 3, on January 20, 2006;(3) and Indiana Michigan Power Company, Donald C. Cook Unit 1, on February 10, 2006.(4)

(1)

NRC letter, Safety Evaluation of Request for Relief from Flaw Removal, Heat Treatment and Nondestructive Examination (NDE) Requirements for the Third 10-Year Inservice Inspection Interval, Three Mile Island Nuclear Station, Unit 1 (TMI-1), Docket No. 50-289, (TAC No. MC1201), dated: July 21, 2004, (ADAMS Accession No. ML0411670510).

(2)

NRC letter, Safety Evaluation for Calvert Cliffs Nuclear Power Plant, Unit No. 2, Docket No. 550-318, Relief Request for Use Weld Overlay and Associated Alternative Inspection Techniques (TAC Nos. MC6219 and MC6220), dated July 20, 2005, (ADAMS Accession No. ML051930316).

(3)

NRC letter, Safety Evaluation of Relief Request IR-2-39 Pertaining to the Repair and Inspection of Nozzle to Safe End Weld, Weld No. 03-X-5641-E-T at Millstone Power Station Unit No. 3 (MPS3) Docket No. 50-423, (TAC No.

MC8609), dated January 20, 2006, (ADAMS Accession No. ML053260012).

(4)

NRC letter, Safety Evaluation of Alternative Regarding Repair of Safe-End-To-Elbow Weld 1-RC-9-01 F at the Donald C. Cook Nuclear Plant Unit 1, Docket No. 50-315, (TAC No. MC8807), dated February 10, 2006, (ADAMS Accession No. ML060240355).

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 11 7.0 Duration of Proposed Alternative The alternative requirements of this request will be applied for the duration of up to and including the last outage of the current 2r"j 10-year IgI interval which includes inservice examination requirements in Enclosure 2 for any applied weld overlays. Future inservice examinations of weld overlays at Seabrook Station beyond this inspection interval will be as required by the NRC in the regulations 8.0 References

1.

ASME Code,Section XI, 1995 Edition, including Addenda through 1996.

2.

EPRI MRP-169 "Technical Basis for Preemptive Weld Overlays for Alloy 82/182 Butt Welds in PWRs", October 2005.

3.

EPRI Report 1013558, Temperbead Welding Applications, 48 Hour Hold Requirements for Ambient Temperature Temperbead Welding, Technical Update, December 2006.

4.

EPRI Report 1014351, Topical Report Supporting and Expedited NRC Review of the Content of the Code Case needed for Dissimilar Metal Weld Overlay Repairs, Final Report, July 2006.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 12 SS Pipe (SA-376 TP3041316)

SWOL (A52I52M)--

S Safe End (SA-182 F316L)

/--SEINozzle Weld A82 RootIA182 Balance

/-Weld Buttering (A182)

Figure 1 - Typical SWOL Configuration

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 13 to to SBK-L-08022

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 14 ASME Code, Appendix VIII, Supplement 11 PDI Program Modifications to Appendix VIII, Supplement 11 PDI Modification 1.0 SPECIMEN REQUIREMENTS 1.1 General (b) The specimen set shall consist of at least Modification: (b) The specimen set shall consist of at least three three specimens having different nominal pipe specimens having different nominal pipe diameters and overlay diameters and overlay thicknesses. They shall thicknesses. They shall include the minimum and maximum nominal pipe diameters for which the examination procedure is include the minimum and maximum nominal applicable. Pipe diameters within a range of 0.9 to 1.5 times a pipe diameters for which the examination nominal diameter shall be considered equivalent. If the procedure is applicable. Pipe diameters within a procedure is applicable to pipe diameters of 24 inches or larger, range of 0.9 to 1.5 times a nominal diameter the specimen set must include at least one specimen 24 inches or shall be considered equivalent. If the procedure larger but need not include the maximum diameter.

The specimen set shall include specimens with overlays not is applicable to pipe diameters of 24 inches or thicker than 0.1 inches more than the minimum thickness, nor larger, the specimen set must include at least thinner than 0.25 inches of the maximum nominal overlay one specimen 24 inches or larger but need not thickness for which the examination procedure is applicable.

include the maximum diameter. The specimen Basis: To avoid confusion, the overlay thickness set must include at least one specimen with tolerance contained in the last sentence was reworded overlay thickness within -0.1 inches to +0.25 and the phrase "and the remainder shall be alternative inches of the maximum nominal overlay flaws" was added to the next to last sentence in thickness for which the procedure is applicable, paragraph 1.1 (d) (1).

(d) Flaw Conditions (1) Base metal flaws.

All flaws must be cracks in or near the butt weld Modification: All flaws must be in or near the butt weld heat-affected zone, open to the inside surface, heat-affected zone, open to the inside surface, and and extending at least 75% through the base extending at least 75% through the base metal wall.

metal wall. Flaws may extend 100% through Intentional overlay fabrication flaws shall not interfere the base metal and into the overlay material; in with ultrasonic detection or characterization of the base this case, intentional overlay fabrication flaws metal flaws. Specimens containing IGSCC shall be used shall not interfere with ultrasonic detection or when available. At least 70% of the flaws in the characterization of the cracking. Specimens detection and sizing tests shall be cracks and the containing IGSCC shall be used when 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 inches.

Basis: This paragraph requires that all base metal flaws be cracks. Implanting a crack requires excavation of the base material on at least one side of the flaw. While this may be satisfactory forferritic materials, it does not produce a useable axial flaw in austenitic materials because the sound beam, which normally passes only

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 15 Appendix VIII, Supplement 11 PDI Modification through base material, must now travel through weld material on at least one side, producing an unrealistic flaw response. To resolve this issue, the PDI Program revised this paragraph to allow use of alternative flaw mechanisms under controlled conditions. For example, alternative flaws shall be limited to when implantation of cracks precludes obtaining an effective ultrasonic response, flaws shall be semi elliptical with a tip width of less than or equal to 0. 002 inches, and at least 70% of the flaws in the detection and sizing test shall be cracks and the remainder shall be alternative flaws. To avoid confusion, the overlay thickness tolerance contained in paragraph 1.1 (b) last sentence, was reworded and the phrase "and the remainder shall be 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 Modification: (1) At least 20% but less than 40% of the base shall be oriented within +/-20 degrees of the pipe metal flaws shall be oriented within +/-20 degrees of the pipe axial axiall deorireti.

withe in20degreeshall e oiee direction. The remainder shall be oriented circumferentially.

Flaws shall not be open to any surface to which the candidate circumferentially. Flaws shall not be open to has physical or visual access.

any surface to which the candidate has physical Basis: The requirement for axially oriented overlay or visual access. The rules of IWA-3300 shall fabrication flaws was excluded from the PDI Program as be used to determine whether closely spaced an improbable scenario. Weld overlays are typically flaws should be treated as single or multiple applied using automated GTA W techniques with the flaws.

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 Modification: (2) Specimens shall be divided into base metal and overlay grading units. Each specimen shall overlay fabrication grading units. Each specimen shall contain one contain one or both types of grading units.

or both types of grading units. Flaws shall not interfere with ultrasonic detection or characterization of other flaws.

(a)(1) A base grading unit shall include at least Modification: (a)(1) A base metal grading unit includes the overlay 3 inches of the length of the overlaid weld. The material and the outer 25% of the original overlaid weld. The base metal grading unit shall extend circumferentially for at least 1 inch and shall start at the weld centerline and be wide enough in the axial overlaid weld and base metal on both sides.

direction to encompass one half of the original weld crown and a The base grading unit shall not include the inner minimum of 0.50 inch of the adjacent base material.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 16 Appendix VIII, Supplement 11 75% of the overlaid weld and base metal overlay material, or base metal-to-overlay interface.

PDI Modification Basis: The phrase "and base metal on both sides, " was inadvertently included in the description of a base metal grading unit, The PDI Program intentionally excludes this requirement because some of the qualification samples include flaws on both sides of the weld. To avoid confusion several instances of the term "cracks " or "cracking" were changed to the term 'flaws" because of the use of alternative flaw mechanisms. Modified to require that a base metal grading unit include at least ]

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 grading unit shall include the overlay metal within 1 inch of the crack location. This portion of the overlay material shall not be used as part of any overlay grading unit.

Modification: (a)(2) When base metal flaws penetrate into the overlay material, the base metal grading unit shall not be used as part of any overlay fabrication grading unit.

(a)(3) When a base grading unit is designed to be unflawed, at least 1 inch of unflawed overlaid weld and base metal shall exist on either side of the base grading unit. The segment of weld length used in one base grading unit shall not be used in another base grading unit. Base grading units need not be uniformly spaced around the specimen.

Modification: (a)(3) Sufficient unflawed overlaid weld and base metal shall exist on all sides of the grading unit to preclude interfering reflections from adjacent flaws.

Basis: Modified to require sufficient unflawed overlaid weld and base metal to exist on all sides of the grading unit to preclude interfering reflections from adjacent flaws, rather than the 1 inch requirement.

(b)(1) An overlay grading unit shall include the overlay material and the base metal-to-overlay interface of at least 6 square inches. The overlay grading unit shall be rectangular, with minimum dimensions of 2 inches.

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

Basis: Modified to require sufficient unflawed overlaid weld and base metal to exist on all sides of the grading unit to preclude interfering reflections from adjacent flaws, rather than the 2 inch requirement.

(b)(2) An overlay grading unit designed to be unflawed shall be surrounded by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 inch around its entire perimeter. The specific area used in one overlay grading unit shall not be used in another overlay grading unit. Overlay grading units need not be spaced uniformly about the specimen.

Modification: (b)(2) Overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 inch at both ends. Sufficient unflawed overlaid weld and base metal shall exist on both sides of the overlay fabrication grading unit to preclude 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.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 17 Appendix VIII, Supplement 11 PDI Modification Basis: Paragraph 1. 1 (e) (2) (b) (2) states that overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 in. at both ends, rather than around its entire perimeter.

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

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.

(f) Sizing Specimen (1) The minimum number of flaws shall be ten.

Modification: (1) The minimum number of flaws shall At least 30% of the flaws shall be overlay be ten. At least 30% of the flaws shall be overlay fabrication flaws. At least 40% of the flaws fabrication flaws. At least 40% of the flaws shall be shall be cracks open to the inside surface.

open to 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.

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

circumferentially.

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

by at least 0.1 inch in the through-wall direction.

2.0 CONDUCT OF PERFORMANCE DEMONSTRATIONS The specimen inside surface and identification Modification: The specimen inside surface and identification shall be concealed from the candidate. All shall be concealed from the candidate. All examinations shall be examinations shall be completed prior to completed prior to grading the results and presenting the results to the candidate. Divulgence of particular specimen results or grading the results and presenting the results to candidate viewing of unmasked specimens after the the candidate. Divulgence of particular performance demonstration is prohibited. The overlay specimen results or candidate viewing of fabrication flaw test and the base metal flaw test may be

U. S. Nuclear Regulatory Commission SBK-L-08022 Attaclment 1 Page 18 Appendix VIII, Supplement 11 PDI Modification unmnasked specimens after the performance performed separately.

demonstration is prohibited.

2.1 Detection Test.

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

present for each specimen.

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

wall thickness.

2.3 Depth Sizing Test.

For the depth sizing test, 80% of the flaws shall Modification:

be sized at a specific location on the surface of (a) The depth sizing test may be conducted separately or in the specimen identified to the candidate. For conjunction with the detection test.

(b) When the depth sizing test is conducted in conjunction with the the remaining flaws, the regions of each detection test and the detected flaws do not satisfy the requirements specimen containing a flaw to be sized shall be of 1. (f), additional specimens shall be provided to the candidate.

identified to the candidate. The candidate shall The regions containing a flaw to be sized shall be identified to the determine the maximum depth of the flaw in candidate. The candidate shall determine the maximum depth of the each region.

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.

3.0 ACCEPTANCE CRITERIA 3.1 Detection Acceptance Criteria.

Examination procedures, equipment, and Modification: Examination procedures are qualified for detection personnel are qualified for detection when the when:

results of the performance demonstration satisfy (a) All flaws within the scope of the procedure are detected and the results of the performance demonstration satisfy the acceptance the acceptance criteria of Table VJII-S2-1 for criteria of Table VIII-S2-1 for false calls.

both detection and false calls. The criteria shall (b) At least one successful personnel demonstration has been be satisfied separately by the demonstration performed meeting the acceptance criteria defined in (c).

results for base grading units and for overlay (c) Examination equipment and personnel are qualified for detection grading units.

when the results of the performance demonstration satisfy the acceptance criteria of Table VIII-S2-1 for both detection and false calls.

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

3.2 Sizing Acceptance Criteria.

(a) The RMS error of the flaw length Modification: (a) The RMS error of the flaw length measurements, as compared to the true flaw measurements, as compared to the true flaw lengths, is lengths, is less than or equal to 0.75 inch. The less than or equal to 0.75 inch. The length of base metal

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 19 Appendix VIII, Supplement 11 PDl Modification length of base metal cracking is measured at the flaws is measured at the 75% through-base-metal 75% through-base-metal position.

position.

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

the overlay material by at least 0.1 inch are Basis: The requirement for reporting all extensions of reported as being intrusions into the overlay cracking into the overlay is omitted from the PDI material.

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.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 20 to to SBK-L-08022

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 21 Alternative Requirements for Dissimilar Metal Weld Overlays In lieu of the requirements of IWA-4410 and IWA-461 1, a defect in austenitic stainless steel or austenitic nickel alloy piping, components, or associated welds may be reduced to a flaw of acceptable size in accordance with IWB-3640 by the addition of a repair weld overlay. All Section XI references are to the 2004 Edition with the 2006 Addenda. For the use of Enclosure 2 with other Editions and Addenda, refer to Table 1. The weld overlay shall be applied by deposition of weld reinforcement (weld overlay) on the outside surface of the piping, component, or associated weld, including ferritic materials when necessary, provided the following requirements are met:

1 GENERAL REQUIREMENTS (a) A full-structural weld overlay shall be applied by deposition of weld reinforcement (weld overlay) on the outside surface of circumferential welds of the low alloy steel components, including nozzles (P-No. 3) to safe ends or piping components (P-No. 8 or 43), inclusive of the UNS N06082 or W86182 welds that join the two items. The design of the overlay may be extended to include the adjacent stainless steel to stainless steel welds (P-No. 8 to P-No. 8).

(b) Enclosure 2 applies to dissimilar metal welds between P-No. 8 or 43 and P-Nos. 1, 3, 12A, 12B, or 12C1 materials. Attachment 2 also applies to dissimilar metal welds between P-No. 8 and P-No. 43 materials joined with austenitic F-No. 43 filler metal, and to welds between P-No. 8 and P-No. 8 materials as described in 1 (a) above.

(c) Weld overlay filler metal shall be austenitic nickel alloy (28% Cr min., ERNiCrFe-7 or ERNiCrFe-7A) applied 360 deg. around the circumference of the item, and deposited using a Welding Procedure Specification (WPS) for groove welding, qualified in accordance with the Construction Code and Owner's Requirements and identified in the Repair/Replacement Plan. As an alternative to the post weld heat treatment (PWHT) requirements of the Construction Code and Owner's requirements, the following provisions may be applied.

(1) Appendix I shall be used for ambient-temperature temper bead welding.

(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 dimension greater than IA 6 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 1 P-Nos. 12A, 12B, and 12C designations refer to specific material classifications originally identified in Section III and subsequently reclassified in a later Edition of Section IX.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 22 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 (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 dimension greater than 1/16 in. (1.5 mm) prior to the application of the structural layers of the weld overlay.

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

The austenitic nickel alloy weld overlay shall consist of at least two weld layers deposited using a filler material with a Cr content of at least 28%. The first layer of weld metal deposited may not be credited toward the required thickness. Alternatively, for PWR applications, a diluted first 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 taken from a mockup prepared in accordance with the WPS for the production weld.

(f) Enclosure 2 is only for welding in applications predicted not to have exceeded thermal neutron fluence of 1 x 1017 (E < 0.5 eV) 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 CRACK GROWTH AND DESIGN (a) Crack Growth Calculation of Flaws in the Original Weld or Base Metal.

The size of all flaws postulated in the original weld or base metal shall be used to define the life of the overlay. In no case shall the inspection interval be longer than the life of the overlay. The inspection interval shall be as specified in 3(c). Crack growth in the original weld or base metal, due to both stress corrosion and fatigue, shall be evaluated.

Flaw characterization and evaluation shall be based on the postulated flaw, if ultrasonic examination of the weld and base material is not performed.

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

(2) For postulated flaws in the original weld or base metal the axial flaw length shall be set at 1.5 in. (38 mm) or the combined width of the weld plus buttering, whichever is greater. The circumferential flaw length shall be assumed to be 360 deg.

(a) If no examination is performed prior to application of the overlay, initial inside-surface-connected planar flaws equal to 75% through the original wall thickness shall be assumed, in both the axial and circumferential directions, consistent with the overlay examination volume in Fig. 2.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 23 (b) in determining the expected life of the overlay, any inside surface comlected planar flaw found by the overlay preservice inspection of 3(b) that exceeds the depth of (2)(a) above shall be used as part of the initial flaw depth. The flaw depth assumed is the detected flaw depth plus the postulated worst-case flaw depth in the unqualified ultrasonic examination region of the pipe wall thickness. An overlay meeting this condition shall be considered a repair.

(b) Structural Design and Sizing of the Overlay. The design of the weld overlay shall satisfy the following, using the assumptions and flaw characterization restrictions in 2(a).

The following design analysis shall be completed in accordance with IWA-4311.

(1) The axial length and end slope of the weld overlay shall cover the weld and 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 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 projected flaw by at least O.754cR-t, where R is the outer radius of the item and t is the nominal wall thickness of the item.

(2) Unless specifically analyzed in accordance with 2(b)(1), the end transition taper of the overlay shall not exceed 30 deg. A slope of not more than 1:3 is recommended..

(3) For full structural overlays, when ultrasonic examination is not performed prior to installation of the weld overlay, the assumed flaw in the underlying base material or weld shall be based on the limiting case of the two below:

(a) 100% through-wall for the entire circumference, or (b) 100% through-wall for 1.5 in. (38 mm) or the combined width of the weld plus buttering, whichever is greater, in the axial direction.

(4) The overlay design thickness shall be verified using only the weld overlay thickness conforming to the deposit analysis requirements of 1(e). The combined wall thickness at the weld overlay and the effects of any discontinuities (e.g., another weld overlay or reinforcement for a branch connection) within a distance of 2.5,i[Ri from the toes of the weld overlay, including the flaw size assumptions defined in 2(b)(3) above, shall be evaluated and meet the requirements of IWB-3640

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 24 (5) 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 EXAMINATION In lieu of all other examination requirements, the examination requirements herein shall be met for the life of the weld 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.

(a) Acceptance Examination (1) The weld overlay shall have a surface finish of 250 micro-in. (6.3 micrometers)

RMS or better and a contour that provides for 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 weld shall be examined using the liquid penetrant method. Surface examination shall be performed on weld attached thermocouple removal areas in accordance with NB-4435(b)(3). The weld overlay shall satisfy the surface examination acceptance criteria for welds of the Construction Code or NB-5300. The adjacent base metal shall satisfy the surface examination acceptance criteria for base material of the Construction Code or NB-2500. If ambient-temperature temper bead welding is required, the liquid penetrant examination of the completed weld overlay shall be conducted after the three tempering layers (i.e., layers 1, 2, and 3) have been in place for at least 48 hr after completion of the third temper bead layer over the ferritic steel.

(3) The acceptance examination volume A-B-C-D in Fig. l(a) plus the heat-affected zone beneath the fusion zone C-D shall be ultrasonically examined to assure adequate fusion (i.e., adequate bond) with the base metal and to detect welding flaws, such as interbead lack of fusion, inclusions, or cracks. If ambient-temperature temper bead welding is required, the ultrasonic examination of the completed weld overlay shall be conducted after the three tempering layers (i.e., layers 1, 2, and 3) over the ferritic steel have been in place for at least 48 hr.

Planar flaws detected in the weld overlay acceptance examination shall meet the preservice examination standards of Table IWB-3514-2. In applying the acceptance standards to planar indications within the volume E-F-G-H, in Fig. 1(b), the thickness "t," shall be used as the nominal wall thickness in Table IWB-3514-2.

For planar indications outside this examination volume, the nominal wall thickness shall be "t 2" as shown in Fig. 1 (c), for volumes A-E-H-D and F-B-C-G.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 25 Laminar flaws in the weld overlay shall meet the following:

(a) Laminar flaws shall meet the acceptance standards of Table IWB-3514-3 with the additional limitation that the total laminar flaw shall not exceed 10% of the weld surface area and that no linear dimension of the laminar flaw area exceeds 3.0 in. (76 mm) or 10 % of the nominal pipe circumference, whichever is greater.

(b) The reduction in coverage of the examination volume A-B-C-D in Fig. 1(a),

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 angle beam examination.

(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 Table IWB-3514-2, with nominal wall thickness as defined above for planar flaws. Both axial and circumferential planar flaws shall be assumed.

(4) After completion of all welding activities, affected restraints, supports, and snubbers shall be VT-3 visually examined to verify that design tolerances are met.

(b) Preservice Inspection (1) The examination volume in Fig. 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 flaws that might have propagated into the upper 25% of the base material or into the weld overlay.

(2) The pre-service examination acceptance standards of Table IWB-3514-2 shall be met for the weld overlay. In applying the acceptance standards, wall thickness, tw, shall be the thickness of the weld overlay. Cracks in the outer 25% of the base metal shall meet the design analysis requirements of 2(b).

(3) The flaw evaluation requirements rules of IWB-3640 shall not be applied to planar flaws identified during pre-service examination that exceed the preservice examination acceptance standards of Table IWB-3514-2.

(c) Inservice Inspection (1) The weld overlay examination volume in Fig. 2 shall be added to the inspection plan. The weld overlay inspection interval shall not be greater than the life of the overlay defined in 2(a) above. The weld overlay shall be ultrasonically examined during the first or second refueling outage following application.

(2) Subarticle Q-4300 will be used with the exception that qualified procedures and personnel will be used in accordance with Appendix VIII, Supplement 11 as modified by the PDI Program.

The weld overlay will be examined in accordance with the PDI qualified procedure from both sides to the fullest extent possible.

(3) The weld overlay examination volume in Fig. 2 shall be ultrasonically examined, to determine if any new or existing planar flaws have propagated into the outer 25% of the base metal 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 inservice examination acceptance standards of Table IWB-3514-2 shall be met for the weld overlay. Planar flaws in the outer 25% of the base metal or underlying

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 26 weld thickness, when applicable, shall meet the design analysis requirements of Paragraph 2(b). If flaw growth in the weld overlay occurs and inservice examination acceptance standards of Table IWB-3514-2 cannot be met, a determination will be made to prove that the flaw is not PWSCC. If the cause is determined to be PWSCC or the cause of the flaw cannot be determined, the flaw shall be repaired and IWB-3600 shall not be used to accept these types of flaws. Flaws due to stress corrosion cracking in the weld overlay that exceed the inservice examination acceptance standards of Table IWB-3514-2 shall not be accepted and result in removal of the weld overlay and the item shall be repaired or replaced.

(5) Weld overlay examination volumes in Fig. 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(c)(1). Twenty-five percent of this population shall be examined at least once during every 10 years.

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

(7) For weld overlay examination volumes with unacceptable indications in accordance with 3(c)(4),

the weld overlay shall be removed, including the original defective weld,, and the item shall be corrected by a repair/replacement activity in accordance with IWA-4000.

(d) Additional Examinations. If inservice examinations reveal an unacceptable indication according to 3(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 unacceptable indications 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 unacceptable indications are found, the entire remaining population of weld overlay examination volumes shall be examined prior to return to service.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 27 4 PRESSURE TESTING A system leakage test shall be performed in accordance with IWA-5000.

5 DOCUMENTATION Use of Attachment 1 shall be documented on Form NIS-2.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 28 A

B

a. Acceptance Examination Volume A-B-C-D 1/2 in. (min.)

__,,J E

1/2 in. (min.)

(Note 1)

V\\""' 1'ý"

' IWIý Y L

H G

b. Thickness (t for Table IWB-3514-2

c. Thickness (t ) for Table IWB-3514-2 Fig. 1 Acceptance Examination Volume and Thickness Definitions Notes:

(1) For axial or circumferential flaws, the axial extent of the examination volume shall extend at least '2 in.(13 mm) beyond the toes of the original weld.

(2) The weld includes the weld end butter, where applied.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 29 t

Examination Volume A-B-C-D Fig. 2 Preservice and Inservice Examination Volume NOTES:

(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 1/2/2 in.

(13 mm) beyond the toes of the original weld.

(2) The weld includes weld end butter, where applied.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 30 MANDATORY APPENDIX I AMBIENT TEMPERATURE TEMPER BEAD WELDING I-I GENERAL REQUIREMENTS (a) This Appendix applies to dissimilar austenitic filler metal welds between P-Nos. 1, 3, 12A, 12B, and 12C1 materials and their associated welds and welds joining P-Nos. 8 or 43 materials to P-Nos. 1, 3, 12A, 12B, and 12C2 materials with the following limitation:

This Appendix shall not be used to repair SA-302 Grade B material unless the material has been modified to include from 0.4% to 1.0% nickel, quenching, tempering, and application of a fine grain practice.

(b) The maximum area of an individual weld overlay based on the finished surface over the ferritic base material shall be 300 in.2 (195,000 mm 2).

(c) Repair/replacement activities on a dissimilar-metal weld in accordance with this Appendix are limited to those along the fusion line of a nonferritic weld to ferritic base material on which 1/8 in. (3 mm) or less of nonferritic weld deposit exists above the original fusion line.

(d) If a defect penetrates into the ferritic base material, repair of the base material, using a nonferritic weld filler material, may be performed in accordance with this Appendix, provided the depth of repair in the base material does not exceed 3A8 in. (10 mm).

(e) Prior to welding, the area to be welded and a band around the area of at least 1 V2 times the component thickness or 5 in. (130 mm), whichever is less, shall be at least 50'F (10°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.

1-2 WELDING QUALIFICATIONS The welding procedures and operators shall be qualified in accordance with Section IX and the requirements of 1-2.1 and 1-2.2.

1-2.1 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 root width and included angle of the cavity in the test assembly shall be no greater than the minimum specified for the repair.

(c) The maximum interpass temperature for the first three layers of the test assembly 2 P-Nos. 12A, 12B, and 12C designations refer to specific material classifications originally identified in Section III and subsequently reclassified in a later Edition of Section IX.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 31 shall be 150'F (66°C).

(d) 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 Fig. I-1.

Discard Transverse Side Bend Reduced Section Tensile Transverse Side Bend Transverse Side Bend Reduced Section Tensile Transverse Side Bend Discard F

,-Weld metal GENERAL NOTE: Base metal Charpy impact specimens are not shown.

FIG. I-1 QUALIFICATION TEST PLATE

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 32 (e) Ferritic base material for the procedure qualification test shall meet the impact test requirements of the Construction Code and Owner's Requirements. If such requirements are not in the Construction Code and Owner's Requirements, the impact properties shall be determined by Charpy V-notch impact tests of the procedure qualification base material at or below the lowest service temperature of the item to be repaired. The location and orientation of the test specimens shall be similar to those required in 1-2.1(f) below, but shall be in the base metal.

(f) Charpy V-notch tests of the ferritic heat-affected zone (HAZ) shall be performed at the same temperature as the base metal test of 1-2.1(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.

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

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

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

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

(1) The welding procedure shall be requalified.

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

1-2.2 Performance Qualification Welding operators shall be qualified in accordance with Section IX.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 33 1-3 WELDING PROCEDURE REQUIREMENTS The welding procedure shall include the following requirements:

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

(b) Dissimilar metal welds shall be made using A-No. 8 weld metal (QW-442) for P-No. 8 to P-No. 1, 3, or 12 (A, B, or C)' weld joints or F-No. 43 weld metal (QW-432) for P-No. 8 or 43 to P-No. 1, 3, or 12 (A, B, or C)1 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 in. (3 mm) overlay thickness with the heat input for each layer controlled to within +/-10% of that used in the procedure qualification test. The heat input of the first three layers shall not exceed 45 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'C) for all weld layers regardless of the interpass temperature used during qualification. The interpass temperature limitation of QW-406.3 need not be applied.

(1) The interpass temperature shall be determined by one of the following methods:

(e. g. pyrometers, temperature indicating crayons,or thermocouples.)

(e) 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.

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 34 2001 Edition with 1995 Edition 1995 Edition 1989 Edition 1986 Edition 2003 Addenda with 1996 with 1995 with 1991 with 1988 through 2004 Addenda Addenda Addenda Addenda Edition with through 2001 through 1995 through 1989 2006Addenda Edition with Edition Edition with 2002 Addenda 1990 Addenda IWA-4000 IWA-4000 IWA-4000 IWA-4000 IWA-4000 &

Repair/Replaceme IWA-7000 nt Activities IWA-4311 IWA -4311 IWA -4311 NA NA Configuration Changes I

IWA-TWA 4410 IWA 4410 IWA 4170 TWA 4120 441OWelding, Brazing, Metal Removal, and Installation -

General Requirements IWA-3300 Flaw IWA-3300 IWA-3300 IWA-3300 IWA-3300 Characterization IWA-4611 Defect IWA-4611 IWA-4421 &

IWA-4170 (b)

IWA-4120 Removal IWA-4424 IWB-3514 IWB-3514 IWB-3514 IWB-3514 IWB-3514 Standards for Category B-F IWB/C/D -3600 IWB/C-3600 IWB/C-3600 IWB/C-3600 IWB/C-3600 Analytical Evaluation IWB/C/D-3640 IWB/C-3640 or IWB/C-3640 IWB/C-3640 IWB/C-3640 Evaluation IWB/C-3650 or IWB/C-or IWB/C-Procedures 3650 36501 I Starting with the 1989 Edition with the 1989 Addenda TABLE 1 REFERENCES FOR ALTERNATIVE EDITIONS AND ADDENDA OF SECTION XI

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 35 to to SBK-L-08022

U. S. Nuclear Regulatory Commission SBK-L-08022 Attachment I Page 36 ENCLOSURE 3 Barrier Laver to Prevent Hot Cracking in High Sulfur Stainless Steel

Background

During recent dissimilar metal weld (DMW) overlay activities, where use of ERNiCrFe-7A (Alloy 52M) and ERNiCrFe-7 (Alloy 52) has been used for the filler metal, flaws in the first layer have occurred in the portion of the overlay deposited on the austenitic stainless steel portions (safe ends, pipe etc.) of the assemblies in some cases.

The applicable stainless steel materials at Seabrook Station (SS) where the full structural weld overlay (SWOL) will be deposited are as follows:

" Pressurizer nozzle safe ends are SA-182 Grade F316L.

" Pressurizer safety, relief and spray piping attached to the corresponding nozzle safe ends are SA-376 TP316.

" Pressurizer surge piping attached to the surge nozzle safe end is SA-376 TP304.

Pipe to nozzle safe end welds are ER308/E308.

Discussion The characteristics of the flaws described above are indicative of hot cracking. This phenomenon has not been observed on the ferritic steel or ENiCrFe-3 (Alloy 182)

DMWs.

Further studies have determined that this problem may occur when using Alloy 52M filler metal on austenitic stainless steel materials with high sulfur content.

Limited tests and evaluations recently performed by AREVA have resulted in the conclusion that welding with Alloy 52M on stainless steel base material with 0.020 wt%

sulfur results in cracking while welding on stainless steel base materials with less than 0.010 wt% have resulted in no cracking.

To reduce the susceptibility of hot cracking occurrence due to welding Alloy 52M on the stainless steel base materials with high sulfur, AREVA has selected ER309L filler metal as the preferred filler metal to provide a barrier layer between the Alloy 52M and the high sulfur stainless steel base material. This filler metal is compatible with the base material and promotes primary weld metal solidification as ferrite rather than austenite.

The ferrite is more accommodating of residual elements therein and in the underlying base material thereby significantly reducing the susceptibility to hot cracking. ER309L is also compatible with the Alloy 52M. However, the barrier layer will necessarily consist of ERNiCr-3 (Alloy 82) being used locally at the interface between the Alloy 182 DMW and the stainless steel item. ER309L welding on Alloy 182 may result in cracking of the ER309L weld.

Welding on high sulfur stainless steel with Alloy 82 has not been a concern relevant to hot cracking occurrence.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 37 AREVA welded a mockup to evaluate the interactive effects, such as hot cracking and lack of fusion, between the Alloy 182 DMW, the stainless steel base material, the ER309L and Alloy 82 barrier layer, and the subsequent Alloy 52M weld overlay. The mockup assembly consisted of a stainless steel pipe (0.020 wt% sulfur) with an Alloy 182 groove weld The barrier layer and overlay were welded in the same sequence as performed in the field (barrier layer ER309L and Alloy 82 and then two layers of Alloy 52M overlay). The barrier layer and overlay welding parameters used in the mockup were similar to those used in the field however slightly reduced wire feed rates were used for conservatism.

The following examinations were performed on the final mockup and no recordable indications were detected:

PT examination was performed on the:

High sulfur stainless steel base material

Alloy 182 Groove Weld

ER309L Barrier Layer

Alloy 82 Barrier Layer

Alloy 52M Overlay Limited PDI UT examination 00 Transducer with Full Coverage 450 Transducer with Full Coverage

OD Creeper Transducer with Full Coverage 600 Transducer with limited coverage (Focal depth exceeded UT procedure allowable in places due to overlay being of insufficient thickness. Only two layers of Alloy 52M were deposited.)

Eight (8) specimens were removed from the around the overlay circumference at approximately 45 degree intervals. Metallographic examination searching for any type of discontinuity, flaw or other anomaly has been performed. No anomalies were observed.

The barrier layer was been successfully implemented on various nozzle SWOLs at North Anna 2 earlier this year.

U. S. Nuclear Regulatory Commission SBK-L-08022 Page 38 Conclusion The barrier layer would use ER309L on the stainless steel and Alloy 82 on the stainless steel near the DMW to stainless steel fusion zone only.

Structural credit would not be assumed for the barrier layer in determining the required minimum overlay thickness.

The barrier layer welding would be performed in accordance with ASME Code Section IX qualified welding procedure specification(s). PT examination would be performed on the barrier layer surface and its volume would be included in the final UT of the overlay.

v t e Letter Sequence Request
TAC:MD5933, (Open)
Initiation Request Acceptance... Administration Questions Answers Results Approval Other: ML080920425, SBK-L-08085, OR12 Structural Weld Overlay Examination Results
MONTHYEAR2008-04-01 [Table View]

SBK-L-08022, Supplement to Request for Use of Structural Weld Overlays as an Alternative Repair Technique

Text

References:

1.0 ASME Code Components Affected

Applicable Code Edition and Addenda

Applicable Code Requirement

Reason for Request

Background

Navigation menu

SBK-L-08022, Supplement to Request for Use of Structural Weld Overlays as an Alternative Repair Technique

Text

References:

1.0 ASME Code Components Affected

Applicable Code Edition and Addenda

Applicable Code Requirement

Reason for Request

Background

Navigation menu

Search