BSEP 17-0033, Proposed In-service Inspection Alternative for Application of Dissimilar Metal Weld Full Structural Overlay

Proposed In-service Inspection Alternative for Application of Dissimilar Metal Weld Full Structural Overlay

ML17096A619
Person / Time
Site:	Brunswick
Issue date:	04/06/2017
From:	William Gideon Duke Energy Progress
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BSEP 17-0033
Download: ML17096A619 (47)

Text

Brunswick Nuclear Plant P.O. Box 10429 Southport, NC 28461 April 6, 2017 10 CFR 50.55a(z)(1)

Serial: BSEP 17-0033 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Brunswick Steam Electric Plant, Unit No. 2 Renewed Facility Operating License No. DPR-62 Docket No. 50-324 Proposed In-service Inspection Alternative for Application of Dissimilar Metal Weld Full Structural Overlay Ladies and Gentlemen:

In accordance with 10 CFR 50.55a(z)(1), Duke Energy Progress, LLC (Duke Energy), is proposing an In-service Inspection (ISI) alternative for the Brunswick Steam Electric Plant (BSEP), Unit No. 2.

During the BSEP Unit 2 refueling outage which began on March 18, 2017, a flaw was found by ultrasonic testing (UT) examination in the nozzle-to-cap weld (i.e., 2B11N9-RPV-FW2CRD52) of the reactor pressure vessel nozzle N9 (i.e., the control rod drive return line). The control rod drive return line was removed and the nozzle capped in 1983. The N9 nozzle-to-end cap weld is a Class 1 dissimilar metal weld located between the low alloy steel reactor pressure vessel and an austenitic Inconel pipe cap. In order to maintain the pressure boundary and structural integrity of the weld, Duke Energy proposes to perform a full structural weld overlay based on the American Society of Mechanical Engineers (ASME) Code Case N-740-2. As a condition of using Code Case N-740-2, the provisions of Appendix Q of ASME Section XI will be met.

The proposed alternative, as described in Enclosure 1, complies with 10 CFR 50.55a(z)(1) and provides an acceptable level of quality and safety. Duke Energy requests approval of the proposed alternative no later than April 7, 2017, in support of the current BSEP Unit 2 refueling outage. summarizes the new regulatory commitments made in this submittal.

U.S. Nuclear Regulatory Commission Page 2 of 2 Please refer any questions regarding this submittal to Mr. Lee Grzeck, Manager - Regulatory Affairs, at (910) 457-2487.

William R. Gideon WRM/wrm

Enclosures:

1. In-service Inspection (ISi) Program Alternative ISl-07, Weld Overlay of Control Rod Drive Return Line Nozzle N9 Dissimilar Metal Weld

2. List of Regulatory Commitments cc (with enclosures):

U.S. Nuclear Regulatory Commission, Region II A TIN: Ms. Catherine Haney, Regional Administrator 245 Peachtree Center Ave, NE, Suite 1200 Atlanta, GA 30303-1257 U.S. Nuclear Regulatory Commission ATTN: Mr. Andrew Hon (Mail Stop OWFN 8G9A) (Electronic Copy Only) 11555 Rockville Pike Rockville, MD 20852-2738 Andrew.Hon@nrc.gov U.S. Nuclear Regulatory Commission ATTN: Ms. Michelle P. Catts, NRC Senior Resident Inspector 8470 River Road Southport, NC 28461-8869 Chair - North Carolina Utilities Commission (Electronic Copy Only) 4325 Mail Service Center Raleigh, NC 27699-4300 swatson@ncuc.net Mr. Cliff Dautrich, Bureau Chief North Carolina Department of Labor Boiler Safety Bureau 1101 Mail Service Center Raleigh, NC 27699-1101

BSEP 17-0033 Enclosure 1 Page 1 of 11 In-service Inspection (ISI) Program Alternative ISI-07 Weld Overlay of Control Rod Drive Return Line Nozzle N9 Dissimilar Metal Weld

1. American Society of Mechanical Engineers (ASME) Code Component Affected Component: Control Rod Drive Return (CRD) Line Nozzle-To-End Cap Dissimilar Metal Weld Code Class: Class 1 Examination B-J, R-A Category: B9.11, R1.20-4 Weld Number: Description Size Materials B211N9-RPV- Control Rod Nominal Low Alloy Steel Reactor Pressure FW2CRD52 Drive Return 5 inch Vessel (RPV) Nozzle/Alloy 82-182 Line Nozzle To Weld/ Alloy 600 End Cap End Cap Weld

- Low Alloy Steel Nozzle - SA-508 Class 2

- Alloy 600 End Cap - SB-166 (N06600)

- Weld - Alloy 82/182 (ER NiCr-3, Spec. SFA 5.14)

2. Applicable Code Edition and Addenda

American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)

Section XI - 2001 Edition through 2003 Addenda (i.e., Reference 1) and ASME Boiler and Pressure Vessel Code,Section XI, Nonmandatory Appendix Q, 2007 Edition through 2008 Addenda (i.e., Reference 16).

3. Applicable Code Requirement

IWA-4411 of the ASME Code,Section XI states:

"Welding, brazing and installation shall be performed in accordance with the Owners Requirements and, except as modified below, in accordance with the original Construction Code of the item."

IWA-4411(a) of the ASME Code,Section XI states in part:

"Later Editions and Addenda of the Construction Code, or a later different Construction Code, either in its entirety or portions thereof, and Code Cases may be used, provided the substitution is as listed in IWA-4221(c)."

IWA-4411(b) of the ASME Code,Section XI states:

"Revised Owners Requirements may be used, provided they are reconciled in accordance with IWA-4222."

BSEP 17-0033 Enclosure 1 Page 2 of 11 IWA-4411(e) of the ASME Code,Section XI states:

"The requirements of IWA-4600(b) may be used when welding is to be performed without the postweld heat treatment required by the Construction Code."

ASME Code,Section XI, Appendix VIII, Supplement 11 (i.e., Reference 2) provides requirements for the qualification requirements for the ultrasonic testing (UT) examination of Full Structural Overlaid Wrought Austenitic Piping Welds.

4. Reason for Proposed Alternative Dissimilar metal welds (DMWs) containing nickel welding alloys 82 and 182 have experienced stress corrosion cracking (SCC) in components operating at pressurized water and boiling water reactor temperatures (i.e., References 5, 8, 9, 10, 11, 12, and 15).

Duke Energy Progress, LLC (Duke Energy) proposes, as an emergent repair, to mitigate the SCC susceptibility of the Brunswick Steam Electric Plant (BSEP), Unit 2 CRD return line (N9) nozzle dissimilar metal weld by installing a full structural weld overlay (FSWOL) on the DMW. This approach provides an alternative to replacement of the component, as a means of restoring full component integrity and assuring the structural integrity of this location.

Currently, there are no NRC approved criteria for a licensee to apply a FSWOL to an Alloy 82/182 DMW. The edition and addenda of ASME Code Section XI applicable to BSEP Unit 2 does not contain requirements for weld overlays. However, DMW overlays have been applied to other RPV nozzle DMWs in the boiling water reactors (BWRs) using alternative requirements. This request proposes to use the guidance of ASME Code Case N-740-2 (i.e., Reference 6), for application of a full structural weld overlay to the N9 nozzle-to-end cap DMW at BSEP Unit 2. Since Code Case N-740-2 has not been approved by the NRC in the latest revision of Regulatory Guide (RG) 1.147, an alternative is required. This request describes the requirements Duke Energy proposes to use to design and install a FSWOL on the N9 nozzle-to-end cap DMW.

Indication Characterization The indication in the N9 nozzle-to-end cap weld is circumferentially oriented and located within the weld and butter. In accordance with IWA-3000 proximity rules, the circumferentially oriented indication has been combined with two embedded axially oriented indications for a combined indication with an estimated length of 6.36 inches and a through-wall dimension of 0.48 inches. The remaining ligament from the outside weld surface is 0.386 inches. The minimum as-left thickness of the weld is 0.829 inches. The indication is located 5.50 inches clockwise from top dead center (TDC) (i.e., looking at the nozzle). The circumferential indication is inside surface connected.

5. Proposed Alternative and Basis for Use Pursuant to 10 CFR 50.55a(z)(1), Duke Energy proposes an alternative to the ASME Code requirements stated above. The alternative and its proposed use are described in Attachment 1 to this request, and includes installation of a FSWOL that structurally replaces

BSEP 17-0033 Enclosure 1 Page 3 of 11 the existing weld and defect. This alternative is based on the methodology contained in ASME Code Case N-740-2.

Appendix VIII, Supplement 11 of the 2001 Edition with Addenda through 2003 of ASME Code,Section XI (i.e., Reference 2) specifies requirements for performance demonstration of UT examination procedures, equipment, and personnel used to detect and size flaws in full structural overlays of wrought austenitic piping welds. Relief is requested to allow use of the Performance Demonstration Initiative (PDI) program implementation of Appendix VIII for qualification of UT examinations used to detect and size flaws in the FSWOLs of this request. The proposed modifications to Appendix VIII, Supplement 11 for use on FSWOLs are detailed in Attachment 3.

The use of this alternative is requested on the basis that the proposed requirements will provide an acceptable level of quality and safety.

Duke Energy plans to apply a full structural Alloy 52M overlay to the dissimilar metal Alloy 82/182 DMW identified in Section 1.

Duke Energy proposes to use ASME Code Case N-740-2 as an alternative to the requirements specified in Section 3 of this request. Code Case N-740-2 has been approved by the ASME Code Committee to specifically allow FSWOLs on nickel alloy DMWs.

However, ASME Code Case N-740-2 has not yet been accepted by the NRC in Regulatory Guide (RG) 1.147, Revision 17. Code Case N-740-2 provides the basis and requirements for the weld overlay techniques. The Code Case N-740-2 design requirements which are applicable to BSEP Unit 2 are detailed in Attachment 1, and the implementation requirements that are applicable are detailed in Attachments 1 and 2. ASME Code Case N-740-2 also incorporates the approved version of ASME Code Case N-638-4 for application of a temper bead surface area over the ferritic low alloy steel RPV nozzle that is as large as 500 square inches.

A comparison of the proposed alternative, Code Case N-740-2, and ASME Code Case N-504-4/Appendix Q is provided in Attachment 4.

The proposed alternative provides an acceptable methodology for mitigating SCC and for mitigating the defect that was detected in this weld to acceptable Code requirements and margins. The use of weld overlay filler metals that are resistant to SCC (e.g., Alloy 52/52M),

weld overlay procedures that create compressive residual stress profiles within the original weld, and post overlay preservice and inservice inspection requirements provide assurance that structural integrity will be maintained for the remaining service life of the weld. The FSWOL will also meet the applicable stress limits from ASME Code Section III. Crack growth evaluations for SCC and fatigue of the as-found flaw demonstrates that structural integrity of the component with the FSWOL in place will be maintained for the remaining service life of the component.

Schematic Configuration for the FSWOL A representation of the FSWOL for the N9 nozzle-to-end cap DMW configuration is presented schematically in Figure 5-1, below.

BSEP 17-0033 Enclosure 1 Page 4of11 RPV CRD Return Line Nozzle Dissimilar Metal Weld The RPV CRD Return Line nozzle is a 5-inch nominal low alloy steel nozzle that is welded to an Alloy 600 end cap. The nozzle is buttered with Alloy 82/182 weld material. The nozzle is also internally clad with stainless steel. The nozzle is welded to the end cap using Alloy 82/182 weld material.

Figure 5-1 Schematic Configuration for the N9 Nozzle, Alloy 82/182 Weld, Alloy 600 End Cap, and FSWOL 5

3.7S'(N0M)

Parts List Material

1. Nozzle SA-508 Class 2

2. Butter Alloy 82/182

3. DMWeld Alloy 82/182

4. End Cap SB-166 (N06600)

5. Weld Overlay Alloy 52M

6. Vessel Cladding Stainless Steel Notes:

1. RPV Nozzle - SA-508 Class 2 low alloy steel, internally buttered with Alloy 82/182 and internally clad with austenitic stainless steel

2. End Cap-Alloy 600, SB-166 (N06600)

Suitability of Proposed Post Overlay Nondestructive Examination (NOE)

As a part of the design of the FSWOL, the FSWOL length, surface finish, and flatness are specified to allow for post-installation, qualified ASME Code Section XI, Appendix VIII UT examinations, as implemented through the ~lectric Power Research Institute (EPRI) POI Program. These examinations include the FSWOL overlay and the required volume of the base material and original weld underneath the FSWOL. The examinations specified in this proposed alternative provide adequate assurance of structural integrity for the following reasons:

• The UT examinations that will be performed with the proposed alternative are in accordance with ASME Code Section XI, Appendix VIII, Supplement 11 (i.e.,

Reference 2), as implemented through the POI Program. These examinations are

BSEP 17-0033 Enclosure 1 Page 5 of 11 considered more sensitive for detection of defects, either from fabrication or service induced, than ASME Code,Section III radiography or UT methods. Further, construction flaws are included in the PDI qualification sample sets for evaluating procedures and personnel.

ASME Code,Section XI has specific acceptance criteria and evaluation methodology to be utilized with the results from these more sensitive UT examinations. The criteria 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 (i.e., Table IWB-3514-2) and for laminar flaws (i.e., Table IWB-3514-3).

A laminar flaw is defined in ASME Code,Section XI as a flaw oriented within 10 degrees of a plane parallel to the surface of the component. This definition is applicable to welds, weld overlays, and base materials. The standard imposed for evaluating laminar flaws in ASME Code,Section XI is more restrictive than the Section III standard for evaluating laminations. The ASME Code,Section XI laminar flaw standards are contained in Table IWB-3514-3 of the ASME Code,Section XI, and are supplemented in Attachment 1. These criteria require that the sum of laminar flaw lengths in any direction must be less than 10% of the overlay length, with a total reduction in area equal to or less than Table IWB-3514-3. For weld overlay areas where examination is precluded by the presence of the flaw, the areas must be postulated to be cracked.

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

Weld overlays for repair of cracks in piping are not addressed by ASME Code,Section III. ASME Code,Section III utilizes NDE procedures and techniques with flaw detection capabilities that are within the practical limits of workmanship standards for welds. These standards are most applicable to volumetric examinations conducted by radiographic examination. Radiography (RT) of weld overlays is not practical because of the presence of radioactive material in the reactor coolant system and water in the pipes. The ASME Code,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 would be rejected using ASME Code,Section III acceptance standards do not have a significant effect on the structural integrity of the component. The proposed alternatives in Attachments 1 and 2 were written to specifically address weld overlays, and not only does this alternative adequately examine the weld overlay, but it provides more appropriate examinations and acceptance criteria than the NRC staff imposed position.

BSEP 17-0033 Enclosure 1 Page 6 of 11 The ASME Code,Section XI acceptance standards are the logical choice for evaluation of potential flaw indications in post-overlay examinations, in which unnecessary repairs to the overlays would result in additional personnel radiation exposure without a compensating increase in safety and quality, and could potentially degrade the effectiveness of the overlays by affecting the favorable residual stress field that they produce. The criteria are consistent with previous criteria approved by the NRC for weld overlay installations. Weld overlays have been used for repair and mitigation of cracking in BWRs for many years. In NRC Generic Letter 88-01, "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping," the NRC approved the use of ASME Code,Section XI inspection procedures for determining the acceptability of installed weld overlays in BWR reactor coolant pressure boundary piping. In addition, the NRC has conditionally accepted ASME Code Case N-504-4 in RG 1.147, Revision 17. ASME Code Case N-504-4 was developed to codify the BWR weld overlay experience, and NRC approval is consistent with the NRC acceptability of BWR weld overlays. Similarly, ASME Code Case N-638-4, has been accepted in RG 1.147, with conditions, for use in both BWR and PWR weld overlay installations using the ASME Code,Section XI acceptance standards. Code Case N-740-2 has since been developed for use on DMWs; NRC review of this code case is still pending.

The NRC found the use of the ASME Code,Section XI, Appendix VIII, Supplement 11 acceptable for identifying both construction and service induced flaws in the Safety Evaluation Report (SER) for James A. Fitzpatrick Nuclear Power Plant dated February 8, 2017; Milestone Power Station Unit 2 dated April 24, 2015; Edwin I. Hatch Nuclear Plant, Unit 1, dated December 18, 2015; and D.C. Cook Plant dated February 19, 2006; and tacitly approved the associated ASME Code,Section XI acceptance criteria, Tables IWB-3514-2 and IWB-3514-3. The NRC also accepted the use of ASME Code,Section XI acceptance standards in an SER dated July 21, 2004, for the Three Mile Island Plant, for disposition of flaws identified in a weld overlay by PDI qualified ultrasonic examinations, with additional restrictions similar to those proposed herein for regions in which inspection is precluded by the flaws. The Hatch submittal is the most recent example of NRC-approved use of Code Case N-740-2 for application to a BWR nozzle DMW.

Suitability of Proposed Ambient Temperature Temper Bead Technique The N9 nozzle FSWOL addressed by this alternative will be performed using ambient temperature temper bead welding in lieu of Post Weld Heat Treatment, in accordance with , and the provisions of this Request for Alternative. Research by EPRI and other organizations on the use of an ambient temperature temper bead process using the machine gas tungsten arc welding (GTAW) process is documented in EPRI Report GC-111050 (i.e., Reference 4). According to the EPRI report, repair welds performed with an ambient temperature temper bead procedure utilizing the machine GTAW 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 Attachment 2 ambient temperature temper bead welding process on mechanical properties of repair welds, hydrogen cracking, cold restraint cracking, and extent of overlay coverage of ferritic base metal are addressed in the following paragraphs.

BSEP 17-0033 Enclosure 1 Page 7 of 11 Mechanical Properties of Repair Welds 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 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 temper bead 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 the weld heat affected zone (HAZ) is possible without the application of preheat. According to Section 2-1 of EPRI Report GC-111050, "the temper bead process is carefully designed and controlled such that successive weld beads supply the appropriate quantity of heat to the untempered heat affected zone such that the desired degree of carbide precipitation (i.e., tempering) is achieved. The resulting microstructure is very tough and ductile."

The ASME Code,Section XI, IWA-4600 temper bead process also includes a postweld soak requirement that is performed at 300 degrees Fahrenheit (F) for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (i.e., P-No. 3 base materials). This postweld soak assists diffusion of any remaining hydrogen from the repair weld. As such, the postweld soak is a hydrogen bake-out and not a postweld heat treatment as defined by the ASME Code. At 300 degrees F, the postweld soak does not stress relieve, temper, or alter the mechanical properties of the weldment in any manner. Since the potential for hydrogen absorption is greatly diminished using the GTAW temper bead process, no postweld soak is needed for this application.

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

Hydrogen Cracking Hydrogen cracking is a form of cold cracking. It is produced by the action of internal tensile stresses acting on low toughness heat affected zones. 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 recombines 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 occurs. 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.

The machine GTAW process is inherently free of hydrogen. Unlike the shielded metal arc welding (SMAW) process, GTAW filler metals do not rely on flux coverings that may be

BSEP 17-0033 Enclosure 1 Page 8 of 11 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 is vaporized ahead of the welding torch. The vapor is prevented from mixing 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 the machine GTAW temper bead process. Therefore, the potential for hydrogen-induced cracking is greatly reduced by using the machine GTAW process.

Extensive research has been performed by EPRI (i.e., Reference 7) which provides a technical basis for starting the 48-hour hold after completing the third temper bead weld layer rather than waiting for the weld overlay to cool to ambient temperature. The hold time required by ASME Code Cases N-638-4 and N-740-2 will be implemented in accordance with this latest research. This approach has been previously reviewed and approved by the NRC for BWR nozzle DMW overlays.

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 temper bead process is designed to provide a sufficient heat inventory, so as to produce the desired tempering for high toughness.

Because the machine GTAW temper bead process provides precision bead placement and control of heat, the toughness and ductility of the heat affected zone is typically superior to the base material. Therefore, the resulting structure must be appropriately tempered to exhibit toughness sufficient to resist cold cracking.

Area Limitation The latest ASME and NRC approved version of ASME Code Case N-638, denoted as N-638-4 in RG 1.147, Revision 17, for temper bead welding, contains a limit of 500 square inches for the surface area of temper bead weld over the ferritic base metal. The associated limitation proposed in this alternative is 500 square inches. The provisions of Code Case N-638-4 have been adopted in their entirety into Code Case N-740-2.

Analyses and Verifications The following list of analyses and verifications will be performed subject to the specific design, analysis, and inspection requirements that have been defined in this relief request.

1. The as-built dimensions of the FSWOL will be measured and evaluated to demonstrate that they equal or exceed the minimum design dimensions of the overlay design.

2. Overall component shrinkage will be measured after the weld overlay application.

3. Nozzle specific stress analyses will be performed within 90 days after application of the FSWOL to establish a residual stress profile in the N9 nozzle. Inside diameter (ID) weld repairs will be assumed in these analyses to effectively bound any actual

BSEP 17-0033 Enclosure 1 Page 9 of 11 weld repairs that may have occurred in the nozzles. The analysis will then simulate application of the FSWOL to determine the final residual stress profile. Post weld overlay residual stresses at normal operating conditions will be shown to result in an improved stress state at the ID of the N9 nozzle weld region that reduces the probability for further crack propagation due to SCC.

4. The analyses will demonstrate that the application of the FSOL satisfies all ASME Code,Section III stress and fatigue criteria will be met for the regions of the overlay remote from observed, or assumed, cracks.

5. Fracture mechanics analyses will be performed to predict crack growth. Crack growth due toSCC and fatigue crack growth in the original DMW will be evaluated.

These crack growth analyses will consider all design loads and transients, plus the post weld overlay through-wall residual stress distributions, and will demonstrate that the assumed cracks shall not grow beyond the design bases for the weld overlay (i.e., through the original DMW thickness and any additional allowance for crack growth within the weld overlay) for the time period until the next scheduled inservice inspection. The crack growth analyses will determine the amount of growth for assumed cracks to grow over the entire intended service life of the weld overlay.

6. The total added weight on the piping system due to the overlay will be evaluated for potential impact on RPV nozzle stresses and dynamic characteristics.

Summaries of the results of the analyses listed in Items 1 and 2 above will be submitted to the NRC prior to entry into Mode 2 following completion of the weld overlay. Items 3 through 6 will be submitted to the NRC within 90 days of completing the BSEP Unit 2 refueling outage B223R1.

The following information will be submitted to the NRC within 14 days of completion of the final UT examination of the overlaid welds. Also, included in the results will be a discussion of any repairs to the overlay material and/or base metal and the reason for the repair.

1. A listing of indications detected in the overlaid weld.

2. The disposition of all indications using the acceptance criteria of ASME Code,Section XI, IWB-3514-2 and/or IWB-3514-3 criteria and, if possible, the type and nature of the indications.

Conclusions Quality and Safety of Proposed Alternative Implementation of the FSWOL alternative to IWA-4600 of ASME Code,Section XI described in Attachments 1 and 2 of this request produces effective repairs for future mitigation of SCC in the identified weld and maintains the nozzle geometry to permit future ASME Code, Appendix VIII UT examinations as implemented through the PDI Program. FSWOL repairs of DMWs have been installed and performed successfully for many years in both PWR and BWR applications. The alternative provides improved structural integrity and reduces the likelihood of leakage at the N9 nozzle. Accordingly, the use of the alternative provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1).

BSEP 17-0033 Enclosure 1 Page 10 of 11

6. Duration of Proposed Alternative The provisions of this alternative are applicable to the fourth 10-year in-service inspection interval for BSEP which commenced on May 11, 2008, and will end on May 10, 2018.

The FSWOL installed in accordance with the provisions of this alternative will remain in place for the design life of the repair established as described in Attachments 1 and 2.

7. References

1. ASME Boiler and Pressure Vessel Code,Section XI, 2001 Edition through 2003 Addenda.

2. ASME Boiler and Pressure Vessel Code,Section XI, 2001 Edition through 2003 Addenda, Appendix VIII, Supplement 11, "Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds."

3. EPRI Report 1021073, "Justification for Extension of the Temper Bead Limit to 1000 Square Inches for WOL of P1 and P3 Materials," June 21, 2010.

4. EPRI Report GC-111050, November 1998, "Ambient Temperature Preheat for Machine GTAW Temper bead Applications," EPRI, Palo Alto, CA, and Structural Integrity Associates, Inc., San Jose, CA.

5. EPRI Materials Reliability Program Report: Crack Growth Rates for Evaluating PWSCC of Alloy 82, 182, and 132 Welds (MRP-115), EPRI, Palo Alto, CA, and Dominion Engineering, Inc., Reston, VA: November 2004. 1006696.

6. ASME Code Case N-740-2, "Dissimilar Metal Weld Overlay for Repair or Mitigation of Class 1, 2, and 3 Items."

7. EPRI Report 1013558, "Temperbead Welding Applications, 48 Hour Hold Requirements for Ambient Temperature Temperbead Welding," EPRI, Palo Alto, CA and Hermann &

Associates, Key Largo, FL, December 2006.

8. W. Hübner, B. Johansson, and M. de Pourbaix, "Studies of the Tendency to Intergranular Stress Corrosion Cracking of Austenitic Fe-Cr-Ni Alloys in High Purity Water at 300°C," Studsvik Report AE-437, Nykoping, Sweden, 1971.

9. W. Debray and L. Stieding, Materials in the Primary Circuit of Water-Cooled Power Reactors, International Nickel Power Conference, Lausanne, Switzerland, May 1972, Paper No. 3.

10. C. Amzallag, et al., "Stress Corrosion Life Assessment of 182 and 82 Welds used in PWR Components," Proceedings of the 10th International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, NACE, 2001.

11. NUREG/CR-6907, "Crack Growth Rates of Nickel Alloy Welds in a PWR Environment,"

U.S. Nuclear Regulatory Commission (Argonne National Laboratory), May 2006

BSEP 17-0033 Enclosure 1 Page 11 of 11

12. EPRI Material Reliability Program Report: "Primary System Piping Butt Weld Inspection and Evaluation Guidelines (MRP-139)," EPRI, Palo Alto, CA: August 2005. 1010087.

13. ASME Code Case N-638-4, "Similar and Dissimilar Metal Welding Using Ambient Temperature GTAW Temper Bead Technique."

14. ASME Code Case N-504-4, "Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping."

15. D. Buisine, et al., "PWSCC Resistance of Nickel Based Weld Metals with Various Chromium Contents," Proceedings: 1994 EPRI Workshop on PWSCC of Alloy 600 in PWRs, EPRI, Palo Alto, CA: 1995. TR-105406, Paper D5.

16. ASME Boiler and Pressure Vessel Code,Section XI, Nonmandatory Appendix Q, 2007 Edition through 2008 Addenda.

SEP 17-0033 Enclosure 1, Attachment 1 Page 1 of 11 Attachment 1 Proposed Alternative for Nozzle N9 to Pipe Cap Dissimilar Metal Weld Overlay A

1.1 INTRODUCTION

Duke Energy proposes the following detailed requirements for the design, analysis, fabrication, examination, and pressure testing of the BSEP Unit 2 Reactor Pressure Vessel (RPV) Control Rod Drive (CRD) Return Line nozzle to end cap dissimilar metal weld overlay. These requirements, which are derived from applicable portions of ASME Code Case N-740-2, provide an acceptable methodology for reducing potential defects in these austenitic nickel alloy welds to an acceptable size or mitigating the potential for future stress corrosion cracking by increasing the wall thickness through deposition of weld overlays. The weld overlay will be applied by deposition of weld reinforcement (i.e., weld overlay) on the outside surface of the piping, nozzle, and associated dissimilar metal weld, including ferritic materials when necessary, in accordance with the following requirements:

A1.2 GENERAL REQUIREMENTS A1.2.1 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 be either mitigative or repair weld overlay as defined in A1.2.1(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 A1.3(a)(3), 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 proposed alternative, the stress-corrosion-cracking (SCC) susceptible materials are Unified Numbering System (UNS) N06600, N06082, or W86182 in pressurized water reactor environments; or UNS N06600, W86182, or austenitic stainless steels and associated welds in boiling water reactor environments.

A1.2.2 General Overlay Requirements (a) A full-structural weld overlay will be applied by deposition of weld reinforcement (i.e., weld overlay) on the outside surface of circumferential welds. This proposed method applies to austenitic nickel alloy and austenitic stainless steel welds between the following:

P-No. 8 or P-No. 43 and P-Nos. 1, 3, 12A, 12B, or 12C P-No. 8 and P-No. 43 Between P-Nos. 1, 3, 12A, 12B, and 12C materials

SEP 17-0033 Enclosure 1, Attachment 1 Page 2 of 11 (b) If a weld overlay on any of the material combinations in A1.2.2(a) obstructs a required examination of an adjacent P-No. 8 to P-No. 8 weld, the overlay will be extended to include overlaying the adjacent weld.

(c) Weld overlay filler metal will be austenitic nickel alloy (i.e., 28 percent chromium minimum, ERNiCrFe-7/7A) meeting the requirements of 1.2(e)(1) or (2), as applicable, applied 360 degrees 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 Owners Requirements identified in the Repair/Replacement Plan.

As an alternative to the post weld heat treatment (PWHT) requirements of the Construction Code and Owners requirements, ambient-temperature temper bead welding in accordance with A2.1 will be used.

(d) Prior to deposition of the weld overlay, the surface to be weld overlaid will be examined using the liquid penetrant method. Indications with major dimensions greater than 1/16 inch (i.e., 1.5 millimeters) will be removed, reduced in size, or weld repaired in accordance with the following requirements:

(1) One or more layers of weld metal will be applied to seal unacceptable indications in the area to be repaired with or without excavation. The thickness of these layers will 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 A1.2.2(d) is required, the area where the weld overlay is to be deposited, including any local weld repairs or initial weld overlay layer, will be examined by the liquid penetrant method. The area shall contain no indications with major dimensions greater than 1/16 inch (i.e., 1.5 millimeters) prior to application of the structural layers of the weld overlay.

(3) Per ASME Code Case N-740-2, to reduce the potential of hot cracking when applying an austenitic nickel alloy over P-No. 8 base metal, a layer or multiple layers of austenitic stainless steel filler material will be applied over the austenitic stainless steel base metal.

The stainless steel filler metal shall have a delta ferrite content of 5 to 15 Ferrite Number (FN), as reported on the Certified Material Test Report. The thickness of these buffer layers will not be used in meeting weld reinforcement design thickness requirements.

Since a stainless steel buffer layer will not be applied for the BSEP Unit 2 N9 overlay, this stipulation of ASME Code Case N-702-2 will not apply.

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

(1) Per ASME Code Case N-740-2, the austenitic stainless steel weld overlay shall consist of at least two weld layers having as-deposited delta ferrite content of at least 7.5 FN.

The first layer of weld metal with delta ferrite content of at least 7.5 FN shall constitute the first layer of the weld reinforcement that may be credited toward the required thickness. Alternatively, layers of at least 5 FN are acceptable, provided the carbon content of the deposited weld metal is determined by chemical analysis to be less than 0.02 percent.

SEP 17-0033 Enclosure 1, Attachment 1 Page 3 of 11 Since an Alloy 52M weld overlay will be used, this stipulation of ASME Code Case N-740-2 will not apply.

(2) The Alloy 52M weld overlay will consist of at least two weld layers deposited using a filler material with a chromium (Cr) content of at least 28 percent. The first layer of weld metal deposited may not be credited toward the required thickness except that 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 20 percent 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 weld procedure for the production weld.

(f) This case is only for welding in applications predicted not to have exceeded thermal neutron (E < 0.5 eV) fluence of 1 x 1017 neutrons per cm2 prior to welding. Duke Energy will confirm the thermal neutron fluence at the N9 nozzle location is less than the threshold specified.

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

A1.3 CRACK GROWTH AND DESIGN (a) Crack Growth Calculation of Flaws in the Original Weld or Base Metal. The size of the flaw detected in the base metal will be used to define the life of the overlay. The inspection interval will not be longer than the shorter of the life of the overlay or the period specified in A1.4(c). Crack growth due to both stress corrosion and fatigue, will be evaluated. Flaw characterization and evaluation will be based on the examination results or postulated flaw, as described below. The flaw is at or near the boundary of two different materials. As such, an evaluation of flaw growth in both materials will be performed.

(1) For the repair overlay, a pre-overlay examination has been performed and the initial flaw size for crack growth in the base metal will be based on the as-found flaw.

(2) Per ASME Code Case N-740-2, for postulated flaws, the axial flaw length will be 1.5 inches (i.e., 38 millimeters) or the combined width of the weld plus buttering plus any adjacent SCC susceptible material, whichever is greater. The circumferential flaw length will be assumed to be 360 degrees. The depths associated with these lengths are specified in A1.3(a)(3) and A1.3(a)(4).

(3) Per ASME Code Case N-740-2, if an ASME Section XI, 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 percent of the original wall thickness will be assumed in both the axial and circumferential directions, and the overlay shall be considered mitigative.

This stipulation of ASME Code Case N-740-2 is not applicable because ultrasonic examinations have determined the identified indication to be ID connected.

SEP 17-0033 Enclosure 1, Attachment 1 Page 4 of 11 (4) Per ASME Code Case N-740-2, if an ASME Section XI, 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 percent 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 (CASS) items, a 100 percent through-wall flaw shall be assumed unless the subsequent inservice inspection schedule is modified as discussed in A1.4(c)(4).

This stipulation of ASME Code Case N-740-2 is not applicable because ultrasonic examinations have been performed prior to applicable of an overlay. In addition, this application does not involve a cast austenitic stainless steel item.

(5) Per ASME Code Case N-740-2, 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 percent of the original wall thickness (i.e., see Figure A1-2 below). For such cases, the initial flaw depths are 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.

This stipulation of ASME Code Case N-740-2 is not applicable because ultrasonic examinations have been performed; however, for the proposed crack growth evaluation, the flaw will be assumed to have 75 percent through-wall depth, for both an axial and circumferential flaw.

(6) In determining the life of the overlay, any inside-surface-connected planar flaw found by the overlay preservice inspection of A1.4(b) that exceeds the depth of (3), (4), or (5) above has been 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. Since the overlay will meet this condition, it is considered a repair, rather than mitigation.

(b) Structural Design and Sizing of the Overlay. The design of the weld overlay will satisfy the following, using the assumptions and flaw characterization requirements in A1.3(a). The following design analysis will be completed in accordance with IWA-4311:

(1) The axial length and end slope of the weld overlay will cover the weld and heat-affected zones on each side of the weld, as well as any stress corrosion cracking 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 will be evaluated in the analysis to ensure that load redistribution complies with the above. These requirements are usually satisfied if the weld overlay full thickness length extends axially beyond the SCC-susceptible material or projected flaw by at least 0.75 Rt , where R is the outer radius of the item and t is the nominal wall thickness of the item 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).

SEP 17-0033 Enclosure 1, Attachment 1 Page 5 of 11 (2) In accordance with A1.3(b)(1), the end transition slope of the overlay will be analyzed for the design configuration.

(3) The assumed flaw in the underlying base material or weld will be based on the limiting case of A1.3(b) or (3)(a) which results in the larger required overlay thickness.

(a) 100 percent through-wall circumferential flaw for the entire circumference.

(b) 100 percent through-wall flaw with length of 1.5 inches (i.e., 38 millimeters), or the combined width of the weld plus buttering plus any SCC-susceptible material, whichever is greater, in the axial direction.

(4) The overlay design thickness will be verified, using only the weld overlay thickness conforming to the deposit analysis requirements of A1.2.2(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 within a distance of 2.5 Rt ,

from the toes of the weld overlay, including the flaw size assumptions defined in A1.3(b)(3) above, will be evaluated and shall meet the requirements of IWB-3640, IWC-3640, or IWD-3640, as applicable.

(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) will be evaluated. For the N9 nozzle weld, there are no existing flaws previously accepted by analytical evaluation that need to be evaluated in accordance with IWB-3640, IWC-3640, or IWD-3640, as applicable.

A1.4 EXAMINATION In lieu of all other examination requirements, the examination requirements of this proposed method will be met for the life of the overlay. Specifically, future inservice examinations required by 10 CFR 50.55a, if more stringent than those specified herein, shall be met in lieu of the proposed inservice examinations included in this relief request. Nondestructive examination methods will 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 will be qualified in accordance with the modified requirements to ASME Code,Section XI, Appendix VIII, Supplement 11 as described in Attachment 3. The examination will be performed, to the maximum extent practicable, for axial and circumferential flaws. If 100 percent coverage of the required volume for axial flaws cannot be achieved, but essentially 100 percent coverage for circumferential flaws (i.e., 100 percent of the susceptible volume) can be achieved, the examination for axial flaws will be performed to achieve the maximum coverage practicable, with limitations noted in the examination report. The examination coverage requirements will be considered to be met.

(a) Acceptance Examination (1) The weld overlay will have a surface finish of 250 micro-inches (µ-in), 6.3 micrometer

(µm) roughness measurement system (RMS) or better and contour that permits ultrasonic examination in accordance with procedures qualified in accordance with

SEP 17-0033 Enclosure 1, Attachment 1 Page 6 of 11 ASME Code,Section XI, Appendix VIII. The weld overlay will be inspected to verify acceptable configuration.

(2) The weld overlay and the adjacent base material for at least 1/2 inch (i.e., 13 millimeters) from each side of the overlay will be examined using the liquid penetrant method. The weld overlay will satisfy the surface examination acceptance criteria for welds of the Construction Code or NB-5300. The adjacent base material will 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 penetrant examination of the completed weld overlay will 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.

(3) The examination volume A-B-C-D in Figure A1-1(a), shown below, will 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 heat-affected zone from the overlay. If ambient temperature temper bead welding is performed, the ultrasonic examination will 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 will meet the preservice examination standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness, t1 or t2 defined in Figure A1-1(b) will 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 stress corrosion cracking. For susceptible material, t1 will be used. If a flaw in the overlay crosses the boundary between the two regions, the more conservative of the two dimensions (t1 or t2) will be used. Laminar flaws in the weld overlay will meet the following requirements:

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

(b) For examination volume A-B-C-D in Figure A1-1(a), shown below, the reduction in coverage due to laminar flaws will be less than 10 percent. 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 will be assumed to contain the largest radial planar flaw that could exist within that volume. This assumed flaw will meet the preservice examination acceptance standards of IWB-3514, with nominal wall thickness as defined above the planar flaws. Alternatively, the assumed flaw will be evaluated and meet the requirements of IWB-3640, IWC-3640, and IWD-3640, as applicable. Both axial and circumferential planar flaws will be assumed.

(4) 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. There are no restraints, support, or snubbers associated with the N9 nozzle; therefore, there are

SEP 17-0033 Enclosure 1, Attachment 1 Page 7of11 no post-welding VT-3 visual examinations of restraints, support, or snubbers that will be necessary.

Figure A 1-1 Examination Volume and Thickness Definitions End Transmon Slope A

D c (a) Examination Volume A-8-C-D A

D H (b) Thickness (t1 and t 2 ) for Table IWB-3514-2 Notes:

1 Dimension bis equivalent to the nominal thickness of the nozzle or pipe being overlaid, as appropriate.

2 The nominal wall thickness is t1 for flaws in E-F-G-H, and t2 for flaws in A-E-H-D or F-B-C-G.

3 For flaws that span two examination volumes (e.g., illustrated at F-G), the t1 thickness shall be used.

4 The weld includes the nozzle or safe end butter, where applied, plus any stress corrosion cracking susceptible base material in the nozzle.

(b) Preservice Inspection

( 1) The examination volume in Figure A 1-2 will be ultrasonically examined. The angle beam will 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 percent of the base metal thickness or into the weld overlay.

SEP 17-0033 Enclosure 1, Attachment 1 Page 8of11 (2) The preservice examination acceptance standards of IWB--3514 will be met for the weld overlay. In applying the acceptance standards to planar indications, the thickness, t 1 or

h. defined in Figure A1-1(b) will 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 sec. For susceptible material, t1 will be used. Planar flaws in the outer 25 percent of the base metal thickness will meet the design analysis requirements of A1 .3(b).

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

Figure A 1-2 Preservice and lnservice Examination Volume Minimum 1/2 in . (13 mm) Minimum 112 in. (13 mm) (Note 1) t/4 1t

~~_/~~~~~~--.__J As-found Flaw ----~

Examination Volume A-B-C-D Notes:

1 The weld includes the nozzle or safe end butter, where applied.

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

(c) lnservice Inspection (1) Category E welds (i.e., cracked welds reinforced by weld overlay) are required by BWRVIP-75-A to be examined on the frequency of 25 percent of the population every 10 years. As such, the FSWOL applied to the N9 nozzle-to-end cap weld will be added to the ISi Program's Category E population and be eligible for inspection at this frequency. All weld overlays, including those not in the 25 percent sample, will be examined prior to the end of their design life as determined in A 1.3(a).

(2) If the weld's pre-overlay examination, post-overlay acceptance examination, or preservice examination reveal planar flaws, or for which a pre-overlay examination was not performed, the weld overlay will be ultrasonically examined during the first or second refueling outage following application. Examination volumes that show no indication of crack growth or new cracking will then be placed into a population of Category E welds

SEP 17-0033 Enclosure 1, Attachment 1 Page 9 of 11 (i.e., cracked welds reinforced by weld overlay) to be examined on a sample basis.

Twenty-five (25) percent of this population will be added to the ISI Program in accordance with BWRVIP-75-A. The 25 percent sample will consist of the same welds in the same sequence during successive intervals to the extent practical provided the 25 percent sample contains welds that experience the hottest operating temperature in the population. If hot leg and cold leg welds are included in the population, the 25 percent sample does not need to include the cold leg welds. All weld overlays, including those not in the 25 percent sample, will be examined prior to the end of their design life as determined in A1.3(a).

(3) The weld overlay examination volume in Figure A1-2 above will be ultrasonically examined to determine if any new or existing planar flaws have propagated into the outer 25 percent of the base material thickness or into the overlay. The angle beam will be directed perpendicular and parallel to the piping axis, with scanning performed in four directions.

(4) Per ASME Code Case N-740-2, for cast stainless steel items, the required examination volume shall be examined to the maximum extent practical including 100 percent of the susceptible material volume (i.e., non-stainless steel volume). This request does not involve a cast stainless steel component. If 100 percent of the susceptible material volume is examined both before and after mitigation, and no inside surface connected planar flaws are detected, the inspection frequency of (1) above for uncracked items is applicable. If 100 percent of the susceptible material is not examined in the pre and post mitigation volume examinations, the inspection frequency of (2) above for cracked items will be applied with the following exceptions:

(a) The inspection of the mitigated weld will not be credited to satisfy the requirement of the 25 percent inspection sample every inspection interval. The mitigated weld shall be inspected each inspection interval.

(b) If the required examination volume, including 100 percent of the susceptible material volume, is subsequently examined using a qualified ultrasonic examination and no planar flaws are detected, the weld may be placed in the 25 percent inspection sample population as noted in (2) above.

(5) The weld overlay will meet the inservice examination acceptance standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness, t1 or t2, defined in Figure A1-1(b) above will 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 will be used. If the acceptance standards of IWB-3514 cannot be met, the weld overlay will meet the acceptance standards of IWB-3600, IWC-3600, or IWD-3600, as applicable. If a planar flaw is detected in the outer 25 percent of the base material thickness will meet the design analysis requirements of A1.3. Any indication characterized as stress corrosion cracking in the weld overlay material will be deemed unacceptable.

(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

SEP 17-0033 Enclosure 1, Attachment 1 Page 10 of 11 overlay examination volume will be reexamined during the first or second refueling outage following discovery of the growth or new flaws.

(7) For weld overlay examination volumes with unacceptable indications in accordance with A1.4(c)(5), the weld overlay and original defective weld will be removed.

A repair/replacement activity will be performed in accordance with IWA-4000.

(d) Additional Examinations. If inservice examinations reveal a defect, in accordance with A1.4(c)(5), 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, will be examined prior to return to service. If additional defects are found in the second sample, 50 percent 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.

Regarding sample expansion, BWRVIP-75-A, Category D, section 3.4.1 states:

If cracking is detected, the sample size will be expanded to a sample equal in number to the size of the initial sample. If cracking is detected in the additional sample, all remaining Category D welds will be examined. Sample expansion can be limited, with technical justification, to the system or type component (i.e., safe-end to nozzle) in which flaws were detected. However, the sample size should include a number equal to the original sample or otherwise include all the welds within the system or component type that expansion is being limited.

Analysis of the 2B11N9-RPV-FW2CRD52 examination has concluded that the characteristics of the observed indication are not typical of IGSCC, and no SCC flaws were detected during the examination. As the intent of BWRVIP-75-A is to provide guidance on IGSCC-related inspections, the sample expansion requirements of Category D should not apply to this observed indication.

When further considering sample expansion, it should be noted that weld 2B11N9-RPV-FW2CRD52 is unique in that it is a cap-to-nozzle nickel-based dissimilar metal weld which experiences no flow, and is located above the top of the active fuel and is not protected by hydrogen water chemistry. This set of conditions is similar to other capped BWR Control Rod Drive (CRD) return nozzles, which have previous industry experience with weld indications. In addition, NRC Information Notice 2004-08, "Reactor Coolant Pressure Boundary Leakage Attributable to Propagation of Cracking in Reactor Vessel Nozzle Welds," concerning cracking on Pilgrim Stations CRD return cap-to-nozzle weld concluded no scope expansion was required based on a comparable set of attributes (i.e., Category D nozzle weld, low hydrogen water chemistry (HWC) protection, dissimilar metal weld).

The current outage scope includes eight additional scheduled BWRVIP-75-A Category D welds, the remaining four welds in Category D have recent satisfactory inspection results, and component 2B11N9-RPV-FW2CRD52 is unique in its component type (i.e., a cap-to-nozzle weld); therefore, sample expansion is not considered to provide any additional benefit. The BSEP Unit 1 N9 nozzle is scheduled for the Spring 2018 refueling outage.

SEP 17-0033 Enclosure 1, Attachment 1 Page 11 of 11 A1.5 PRESSURE TESTING A system leakage test will be performed in accordance with IWA-5000.

A1.6 DOCUMENTATION Use of this proposed method will be documented on Form NIS-2A.

BSEP 17-0033 Enclosure 1, Attachment 2 Page 1 of 5 Attachment 2 Ambient Temperature Temper Bead Welding A2.1 AMBIENT-TEMPERATURE TEMPER BEAD WELDING A2.2 GENERAL REQUIREMENTS (a) This Attachment applies to dissimilar austenitic filler metal welds between P-Nos. 1, 3, 12A, 12B, and 12C materials and their associated welds and welds joining P-No. 8 or 43 materials to P-Nos. 1, 3, 12A, 12B, and 12C materials with the following limitation. This Attachment will not be used to repair SA-302 Grade B material unless the material has been modified to include from 0.4 percent to 1.0 percent 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 will be 500 square inches (i.e., 325,000 square millimeters).

(c) Repair/replacement activities on a dissimilar-metal weld in accordance with this Attachment are limited to those along the fusion line of a nonferritic weld to ferritic base material on which 1/8 inch (i.e., 3 millimeters) 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 Attachment, provided the depth of repair in the base material does not exceed 3/8 inch (i.e.,

10 millimeters).

(e) Prior to welding, the area to be welded and a band around the area of at least 11/2 times the component thickness or 5 inches (i.e., 130 millimeters), whichever is less, will be at least 50 degrees Fahrenheit (i.e., 10 degrees Celsius).

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

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

A2.3 WELDING QUALIFICATIONS The welding procedures and operators will be qualified in accordance with ASME Code Section IX and the requirements of A2.3.1 and A2.3.2.

A2.3.1 Procedure Qualification (a) The base materials for the welding procedure qualification will be of the same P-Number and Group Number as the materials to be welded. The materials will be postweld heat treated to at least the time and temperature that was applied to the materials being welded.

BSEP 17-0033 Enclosure 1, Attachment 2 Page 2 of 5 (b) The maximum interpass temperature for the first three layers of the test assembly will be 150 degrees Fahrenheit (i.e., 66 degrees Celsius).

(c) The weld overlay will be qualified using groove weld coupon. The test assembly groove depth will be at least 1 inch (i.e., 25 millimeters). The test assembly thickness will be at least twice the test assembly groove depth. The test assembly will be large enough to permit removal of the required test specimens. The test assembly dimensions on either side of the groove will be at least 6 inches (i.e., 150 millimeters). The qualification test plate will be prepared in accordance with Figure A2-1 below.

(d) Ferritic base material for the procedure qualification test will meet the impact test requirements of the Construction Code and Owners Requirements. If such requirements are not in the Construction Code and Owners 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 will be similar to those required in A2.3.1(e) but shall be in the base metal.

(e) Charpy V-notch tests of the ferritic heat-affected zone (HAZ) will be performed at the same temperature as the base metal test of A2.3.1(d). Number, location, and orientation of test specimens will be as follows:

(1) The specimens will 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 will be taken transverse to the axis of the weld and etched to define the HAZ. The notch of the Charpy V-notch specimen will 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) If the material thickness permits, the axis of a specimen will 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 will be oriented parallel to the principal direction of rolling or forging.

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

(f) The average lateral expansion value of the three HAZ Charpy V-notch specimens will 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 Attachment, either of the following will be performed:

(1) The welding procedure will be requalified.

BSEP 17-0033 Enclosure 1, Attachment 2 Page 3 of 5 (2) An Adjustment Temperature for the procedure qualification will be determined in accordance with the applicable provisions of Paragraph NB-4335.2 of Section III, 2001 Edition with the 2002 Addenda of the ASME Code. The reference nil-ductility temperature (RTNDT) or lowest service temperature of the materials for which the welding procedure will be used will be increased by a temperature equivalent to that of the Adjustment Temperature.

A2.3.2 Performance Qualification Welding operators will be qualified in accordance with ASME Code,Section IX.

A2.4 WELDING PROCEDURE REQUIREMENTS The welding procedure will include the following requirements:

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

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

(c) The area to be welded will be buttered with a deposit of at least three layers to achieve at least 1/8 inch (i.e., 3 millimeters) overlay thickness with the heat input for each layer controlled to within +/-10 percent of that used in the procedure qualification test. The heat input of the first three layers will not exceed 45 kilojoule (kJ)/inch or 1.8 kJ/millimeter under any conditions. Particular care will 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 heat affected zone and ferritic base metal are tempered. Subsequent layers will 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 will be 350 degrees Fahrenheit (i.e., 180 degrees Celsius) for all weld layers regardless of the interpass temperature used during qualification. The interpass temperature limitation of QW-406.3 will not be applied.

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

(1) Temperature measurement (e.g., pyrometers, temperature-indicating crayons, and thermocouples) during welding. If direct measurement is impractical, interpass temperature will be determined in accordance with A2.4(e)(2) or (3).

If it is impractical to use the interpass temperature measurement methods of A2.4(e)(1) due to extenuating radiological conditions, the provisions of A2.4(e)(2) and (3) may be used.

(2) Heat-flow calculations, using at least the variables listed below:

(a) welding heat input (b) initial base material temperature

BSEP 17-0033 Enclosure 1, Attachment 2 Page 4 of 5 (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 will be used in welding the test coupon.

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

BSEP 17-0033 Enclosure 1, Attachment 2 Page 5 of 5 Figure A2-1 Qualification Test Plate Discard Transverse Side Bend Reduced Section Tensile Transverse Side Bend A

HAZCharpy A V-Notch A.

Transverse Side Bend Reduced Section Tensile Transverse Side Bend Discard Fusion line Weld metal Note:

Base metal Charpy impact specimens are not shown. This figure illustrates a similar-metal weld.

BSEP 17-0033 Enclosure 1, Attachment 3 Page 1 of 8 Attachment 3 Proposed Changes to ASME Code,Section XI, Appendix VIII for Compatibility With the Performance Demonstration Initiative Program Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative Wrought Austenitic Piping Welds to Supplement 11 Requirements Title Alternative: Qualification Requirements for Overlaid Wrought Austenitic Piping Welds:

Basis: The title was clarified to be applicable for all overlays on wrought austenitic piping welds.

The specific qualification shall detail the range of qualification.

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 nominal pipe diameters and overlay thicknesses.

They shall include the minimum and Alternative: (b) The specimen set shall include maximum nominal pipe diameters for which specimens with overlays not thicker than the examination procedure is applicable.

0.1 inch more than the minimum thickness, nor Pipe diameters within a range of 0.9 to 1.5 thinner than 0.25 inch of the maximum nominal times a nominal diameter shall be considered overlay thickness for which the examination equivalent. If the procedure is applicable to procedure is applicable.

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

0.1 inch to plus 0.25 inch of the maximum nominal overlay thickness for which the procedure is applicable.

(d) Flaw Conditions (1) Base metal flaws. All flaws must be Alternative: (1) ... must be in or extending at cracks in or near the approximate butt weld least 50 percent throughintentional overlay heat-affected zone, open to the inside fabrication flaws shall not interfere with surface, and extending at least 75 percent ultrasonic detection or characterization of the through the base metal wall. Flaws may base metal flaws. Specimens containing extend 100 percent through the base metal intergranular stress corrosion cracking shall be and into the overlay material; in this case, used when available. At least 70 percent of the intentional overlay fabrication flaws shall not flaws in the detection and sizing tests shall be interfere with ultrasonic detection or cracks and the remainder shall be alternative characterization of the cracking. Specimens flaws. Alternative flaw mechanisms, if used, containing IGSCC shall be used when shall provide crack-like reflective characteristics

BSEP 17-0033 Enclosure 1, Attachment 3 Page 2 of 8 Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative Wrought Austenitic Piping Welds to Supplement 11 Requirements available. 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 and to extend at least 75 percent 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 than or equal to 0.002 inches, and at least 70 percent 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. Additionally, 1.1(d)(1) was revised to state that flaws must extend at least 50 percent through the base metal wall. This allows qualification to take advantage of additional test specimens to demonstrate increased examination depth.

(e) Detection Specimens (1) At least 20 percent but less than Alternative: (1) At least 20 percent but less 40 percent of the flaws shall be oriented than 40 percent of the base metal flaws shall be

BSEP 17-0033 Enclosure 1, Attachment 3 Page 3 of 8 Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative Wrought Austenitic Piping Welds to Supplement 11 Requirements within +/-20° of the pipe axial direction. The oriented within +/-20 degrees of the pipe axial remainder shall be oriented circumferentially. direction. The remainder shall be oriented Flaws shall not be open to any surface to circumferentially. Flaws shall not be open to any which the candidate has physical or visual surface to which the candidate has physical or access. The rules of IWA-3300 shall be used visual access.

to determine whether closely spaced flaws Basis: The requirement for axially oriented should be treated as single or multiple flaws. 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 shall be sized based on their individual merits.

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

contain one or both types of grading units.

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

Alternative: (a)(1) A base metal grading unit includes the overlay material and the outer 50 percent of the original overlaid weld. The (a)(1) A base grading unit shall include at base metal grading unit shall extend least 3 inch of the length of the overlaid weld. circumferentially for at least 1 inch and shall The base grading unit includes the outer start at the weld centerline and be wide enough 25 percent of the overlaid weld and base in the axial direction to encompass one half of metal on both sides. The base grading unit the original weld crown and a minimum of shall not include the inner 75 percent of the 0.50 inch of the adjacent base material.

overlaid weld and base metal overlay Basis: The phrase "and base metal on both material, or base metal-to-overlay interface. 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.

BSEP 17-0033 Enclosure 1, Attachment 3 Page 4 of 8 Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative Wrought Austenitic Piping Welds to Supplement 11 Requirements 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 1 inch of the length of the overlaid weld, rather than 3 inches.

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

inch of the crack location. This portion of the Basis: Substituted terms provide clarification overlay material shall not be used as part of and are consistent with 1d(1) above. The PDI any overlay grading unit. program adjusts for this conservative change for excluding this type grading unit.

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

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

specimen.

Alternative: (b)(1) An overlay fabrication grading unit shall include the overlay material and the base metal-to-overlay interface for a length of at least 1 inch Basis: The PDI program reduces the base (b)(1) An overlay grading unit shall include metal-to-overlay interface to at least 1 inch (in the overlay material and the base metal-to-lieu of a minimum of 2 inches) and eliminates overlay interface of at least 6 in2. The overlay the minimum rectangular dimension. This grading unit shall be rectangular, with criterion is necessary to allow use of existing minimum dimensions of 2 inches.

examination specimens that were fabricated in order to meet NRC Generic Letter 88-01. This criterion may be more challenging than the ASME Code because of the variability associated with the shape of the grading unit.

(b)(2) An overlay grading unit designed to be Alternative: (b)(2) Overlay fabrication grading unflawed shall be surrounded by unflawed units designed to be unflawed shall be overlay material and unflawed base metal-to- separated by unflawed overlay material and overlay interface for at least 1 inch around its unflawed base metal-to-overlay interface for at

BSEP 17-0033 Enclosure 1, Attachment 3 Page 5 of 8 Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative Wrought Austenitic Piping Welds to Supplement 11 Requirements entire perimeter. The specific area used in least 1 inch at both ends. Sufficient unflawed one overlay grading unit shall not be used in overlaid weld and base metal shall exist on both another overlay grading unit. Overlay grading sides of the overlay fabrication grading unit to units need not be spaced uniformly about the preclude interfering reflections from adjacent specimen. 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: 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 inch at both ends, rather than around its entire perimeter.

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

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

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

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 Alternative: (3) Base metal flaws sizing demonstrations shall be oriented usedcircumferentially.

BSEP 17-0033 Enclosure 1, Attachment 3 Page 6 of 8 Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative Wrought Austenitic Piping Welds to Supplement 11 Requirements circumferentially. Basis: Clarified wording to be consistent with 1.1(d)(1) above.

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

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

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

flaw test may be performed separately.

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

candidate viewing of unmasked specimens after the performance demonstration is prohibited.

2.1 Detection Test.

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

the candidate, the candidate shall be made Basis: Clarified wording similar to 1.1(e)(2) aware of the type or types of grading units above.

(base or overlay) that are present for each specimen.

2.2 Length Sizing Test (d) For flaws in base grading units, the Alternative: (d) For . . . base metal grading . . .

candidate shall estimate the length of that 50 percent of the base metal wall thickness.

part of the flaw that is in the outer 25 percent Basis: Clarified wording for consistency and to of the base wall thickness. be consistent with 1.1(d)(1) above.

2.3 Depth Sizing Test.

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

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

to be sized shall be identified to the candidate.

The candidate shall determine the maximum

BSEP 17-0033 Enclosure 1, Attachment 3 Page 7 of 8 Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative Wrought Austenitic Piping Welds to Supplement 11 Requirements 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 Alternative: Examination procedures are Examination procedures, equipment, and qualified for detection when:

personnel are qualified for detection when

a. All flaws within the scope of the procedure are the results of the performance demonstration detected and the results of the performance satisfy the acceptance criteria of Table demonstration satisfy the acceptance criteria of Vlll-S2-1 for both detection and false calls.

Table VIII-S2-1 for false calls.

The criteria shall be satisfied separately by

b. At least one successful personnel the demonstration results for base grading demonstration has been performed meeting the units and for overlay grading units.

acceptance criteria defined in (c).

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

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

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

3.2 Sizing Acceptance Criteria (a) The RMS error of the flaw length measurements, as compared to the true flaw Alternative: (a) The...base metal flaws lengths, is less than or equal to 0.75 inch. is50 percent through-base-metal position.

The length of base metal cracking is Basis: Clarified wording to be consistent with measured at the 75 percent through-base- 1.1(d)(1) above.

metal position.

Alternative: This requirement is omitted.

(b) All extensions of base metal cracking into Basis: The requirement for reporting all the overlay material by at least 0.1 inch are extensions of cracking into the overlay is reported as being intrusions into the overlay omitted from the PDI Program because it is material.

redundant to the RMS calculations performed in paragraph 3.2(c) and its presence adds

BSEP 17-0033 Enclosure 1, Attachment 3 Page 8 of 8 Supplement 11 - Qualification PDI Program:

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

BSEP 17-0033 Enclosure 1, Attachment 4 Page 1 of 7 Attachment 4 Comparison of ASME Code Case N-504-4 and Appendix Q of ASME Code,Section XI With the Proposed Alternative of Attachment 1 for Weld Overlay, Code Case N-740-2 ASME Code Case N-504-4 and Appendix Q of ASME Code Proposed Alternative of Attachment 1-Code Case N-740-2 Section XI ASME Code Case N-504-4 provides requirements for reducing a The proposed alternative of Attachment 1 provides requirements defect to a flaw of acceptable size by deposition of weld for installing a repair or preemptive full structural weld overlay by reinforcement (weld overlay) on the outside surface of the pipe deposition of weld reinforcement (i.e., weld overlay) on the using austenitic stainless steel filler metal as an alternative to outside surface of the item using Nickel Alloy 52M filler metal.

defect removal. ASME Code Case N-504-4 is applicable to Attachment 1 is applicable to dissimilar metal welds associated austenitic stainless steel piping only. According to Regulatory with nickel alloy materials. The proposed alternative of Guide 1.147, Revision 17, the provisions of Nonmandatory Attachment 1 is based on ASME Code Case N-740-2.

Appendix Q of ASME Code Section XI must also be met when using this Case. Therefore, the Code Case N-504-4 requirements presented below have been supplemented by Appendix Q of ASME Code Section XI.

General Requirements General Requirements ASME Code Case N-504-4 and Appendix Q are only applicable As specified in paragraph 1.1(a), the proposed alternative is to P-No. 8 austenitic stainless steels. applicable to dissimilar metal 82/182 welds joining P-No. 3 to P-No. 8 or 43 materials and P-No. 8 to P-No. 43 materials. It is also applicable to austenitic stainless steel welds joining P-No. 8 materials.

Basis: ASME Code Case N-504-4 and Appendix Q are applicable to austenitic weld overlays of P-No. 8 austenitic stainless steel materials. Based on ASME Code Case N-740-2, the proposed alternative of Attachment 1 was specifically written to address the application of weld overlays over dissimilar metal welds and austenitic stainless steel welds.

According to paragraph (b) of ASME Code Case N-504-4 as The weld filler metal and procedure requirements of paragraph supplemented by Appendix Q, weld overlay filler metal shall be 1.1(b) are equivalent to ASME Code Case N-504-4 and

BSEP 17-0033 Enclosure 1, Attachment 4 Page 2 of 7 ASME Code Case N-504-4 and Appendix Q of ASME Code Proposed Alternative of Attachment 1-Code Case N-740-2 Section XI low carbon (0.035 percent max.) austenitic stainless steel applied Appendix Q except as noted below:

360 degrees around the circumference of the pipe, and shall be deposited using a Welding Procedure Specification for groove

• Weld overlay filler metal shall be austenitic Nickel Alloy 52M welding, qualified in accordance with the Construction Code and (ERNiCrFe-7A) filler metal which has a chromium content of at Owner's Requirements and identified in the Repair/Replacement least 28 percent. If a stainless steel buffer layer is used as Plan. permitted by N-740-2, the ferrite content of the filler material shall be 5 - 15 FN as required by the Construction Code.

As an alternative to post-weld heat treatment, the provisions for "Ambient Temperature Temper Bead Welding" may be used on the ferritic nozzle as described in Attachment 2.

Basis: The weld overlay shall be deposited with ERNiCrFe-7A (Alloy 52M) filler metal. It has been included into ASME Code Section IX as F-No. 43 filler metals. Containing 28.0 -

31.5 percent chromium (i.e., roughly twice the chromium content of 82/182 filler metal), this filler metal has excellent resistance to stress corrosion cracking. This point has been clearly documented in EPRI Technical Report MRP-115, Section 2.2[5].

Regarding the welding procedure specification (WPS), the requirements of Attachments 1 and 2 provide 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 temper bead WPS shall be used. Suitability of an ambient temperature temper bead WPS is addressed in Section 5 of this Request According to paragraph (e) of ASME Code Case N-504-4 as The weld overlay described in Attachment 1 is deposited using supplemented by Appendix Q, the weld reinforcement shall nickel Alloy 52M filler metal instead of austenitic stainless steel consist of at least two weld layers having as-deposited delta filler metals. Therefore, the basis for crediting the first layer ferrite content of at least 7.5 FN. The first layer of weld metal with towards the required design thickness is based on the chromium delta ferrite content of at least 7.5 FN shall constitute the first content of the nickel alloy filler metal. According to paragraph

BSEP 17-0033 Enclosure 1, Attachment 4 Page 3 of 7 ASME Code Case N-504-4 and Appendix Q of ASME Code Proposed Alternative of Attachment 1-Code Case N-740-2 Section XI layer of the weld reinforcement that may be credited toward the A1.1(e), the first layer of nickel Alloy 52M deposited weld metal required thickness. Alternatively, first layers of at least 5 FN may be credited toward the required thickness provided the provided the carbon content is determined by chemical analysis portion of the layer over the austenitic base material, austenitic to be less than 0.02 percent. weld, and the associated dilution zone from an adjacent ferritic base material contains at least 20 percent 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 shall 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 percent chromium. This is a sufficient amount of chromium to prevent stress corrosion cracking. Section 2.2 of EPRI Technical Report MRP-115 states the following: "The only well explored effect of the compositional differences among the weld alloys on primary water stress corrosion cracking is the influence of chromium. Buisine, et al. (Reference 24) evaluated the primary water stress corrosion cracking resistance of nickel-based weld metals with various chromium contents ranging from about 15 percent to 30 percent chromium. Testing was performed in doped steam and primary water. Alloy 182, with about 14.5 percent chromium, was the most susceptible. Alloy 82 with 18-20 percent chromium took three or four times longer to crack. For chromium contents between 21 and 22 percent, no stress corrosion crack initiation was observed ... "

Design and Crack Growth Considerations Design and Crack Growth Considerations The design and flaw characterization provisions of ASME Code The design and flaw evaluation provisions in the proposed Case N-504-4, paragraphs (f) and (g) as supplemented by alternative are the same as ASME Code Case N-504-4 as Appendix Q are summarized below: supplemented in Appendix Q with the exceptions below. The proposed design and flaw evaluation provisions are based on (i) Flaw characterization and evaluation are based on the as- postulated flaws or as-found flaws.

BSEP 17-0033 Enclosure 1, Attachment 4 Page 4 of 7 ASME Code Case N-504-4 and Appendix Q of ASME Code Proposed Alternative of Attachment 1-Code Case N-740-2 Section XI found flaw. Flaw evaluation of the existing flaws is based on IWB-3640 for the design life.

• For weld overlay crack growth evaluations, a flaw with a depth of 10 percent and a circumference of 360 degrees shall be

• Multiple circumferential flaws shall be treated as one flaw of assumed or the as-found flaw size shall be used. The size of the length equal to the sum of the lengths of the individual flaws. flaws shall be projected to the end of the design life of the overlay. Crack growth, including both stress corrosion and fatigue

• Circumferential flaws are postulated as 100 percent through- crack growth, shall be evaluated in the materials in accordance wall for the entire circumference with one exception. When the with IWB-3640. If the flaw is at or near the boundary of two combined length of circumferential flaws does not exceed different materials, evaluation of flaw growth in both materials is 10 percent of the circumference, the flaws are only assumed to required.

be 100 percent through-wall for the combined length of the flaws.

Basis: A preservice volumetric examination shall be performed

• For axial flaws 1.5 inches or longer, or for five or more axial after application of the weld overlay using an ASME Code flaws of any length, the flaws shall be assumed to be 100 percent Section XI, Appendix VIII (i.e., as implemented through PDI) through-wall for the axial length of the flaw and entire examination procedure. This examination shall verify that there is circumference of the pipe. no cracking in the upper 25 percent of the original weld and base material for a full structural weld overlay. The preservice (ii) For four or fewer axial flaws less than 1.5 inches in length, the examination shall also demonstrate that the assumed through-weld overlay thickness need only consist of two or more layers of wall crack depths are conservative. However, if any crack-like weld metal meeting the deposit analysis requirements. flaws are identified in the upper 25 percent of the original weld or base material by the preservice examination, then the as-found (iii) The axial length and end slope of the weld overlay shall cover flaw (i.e., postulated 75 percent through-wall flaw plus the portion the weld and HAZs on each side of the weld, and shall provide of the flaw in the upper 25 percent) shall be used for the crack for load redistribution from the item into the weld overlay and growth analysis. With regard to design, flaws are considered to back into the item without violating applicable stress limits of the be either 75 percent through-wall for assumed crack depth or Construction Code. Any laminar flaws in the weld overlay shall be 100 percent through the original weld when a flaw is identified by evaluated in the analysis to ensure that load redistribution inspection and no structural credit is taken for the weld. All other complies with the above. These requirements are usually met if requirements are equivalent to ASME Code Case N-504-4 as the weld overlay extends beyond the projected flaw by at least supplemented by Appendix Q.

0.75(Rt)1/2.

(iv) Unless specifically analyzed, the end transition slope of the overlay shall not exceed 45 degrees, and a slope of not more

BSEP 17-0033 Enclosure 1, Attachment 4 Page 5 of 7 ASME Code Case N-504-4 and Appendix Q of ASME Code Proposed Alternative of Attachment 1-Code Case N-740-2 Section XI 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 (for example, another weld overlay or reinforcement for a branch connection) within a distance of 0.75(Rt)1/2 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 existing flaws previously accepted by analytical evaluation shall be evaluated in accordance with IWB-3640, IWC-3640, or IWD-3640, as applicable.

Examination and Inspection Examination and Inspection Acceptance Examination The acceptance standards in Attachment 1 are identical to those Q-4100(c) states that the examination volume in Figure Q-4100-1 of paragraph Q-4100(c) except that the proposed method shall be ultrasonically examined to assure adequate fusion (that includes requirements and clarifications that are not included in is, adequate bond) with the base metal and to detect welding Appendix Q. First, it specifies that the ultrasonic examination flaws, such as inter-bead lack of fusion, inclusions, or cracks. 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 third Planar flaws shall meet the preservice examination standards of layer of the weld overlay when ambient temperature temper bead Table IWB-3514-2. Laminar flaws shall meet the following: 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 HAZ from the weld overlay.

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

Basis: Appendix Q is applicable to austenitic stainless steel materials only; therefore, ambient temperature temper bead

BSEP 17-0033 Enclosure 1, Attachment 4 Page 6 of 7 ASME Code Case N-504-4 and Appendix Q of ASME Code Proposed Alternative of Attachment 1-Code Case N-740-2 Section XI welding would not be applicable. It is applicable to welding performed in the proposed alternative. When ambient temperature temper bead 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 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after completion of the third layer of the weld overlay is provided in Section 5 of the Request.

The other two changes are simply clarifications that were added to ensure that the examination requirements were appropriately performed.

Q-4100(c)(1) states that laminar flaws shall meet the acceptance The acceptance standards of the proposed method are identical standards of Table IWB-3514-3. to paragraph Q-4100(c)(1) except that the proposal includes the additional limitation that the total laminar flaw shall not exceed 10 percent 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 un-inspectable volume beneath a laminar flaw. See Section 5 of this Request for additional information.

Q-4100(c)(4) allows the performance of radiography in The acceptance standards of the proposed alternative do not accordance with the Construction Code as an alternative to include the radiographic alternative of paragraph Q-4100(c)(4).

Q-4100(c)(3).

Basis: The ultrasonic examinations performed in accordance with the proposed alternative are in accordance with ASME Code,Section XI, Appendix VIII, Supplement 11 as implemented through the PDI. These examinations are considered more sensitive for detection of defects, either from fabrication or service-induced, than either ASME Code Section III radiographic or ultrasonic methods. Furthermore, construction type flaws have been included in the PDI qualification sample sets for evaluating

BSEP 17-0033 Enclosure 1, Attachment 4 Page 7 of 7 ASME Code Case N-504-4 and Appendix Q of ASME Code Proposed Alternative of Attachment 1-Code Case N-740-2 Section XI procedures and personnel. See Section 5 of this Request for additional justification.

Preservice Inspection Preservice Inspection Q-4200(b) states that the preservice examination acceptance The acceptance standards of the proposed alternative are standards of Table IWB-3514-2 shall be met for the weld overlay. identical to paragraph Q-4200(b) except proposed alternative Cracks in the outer 25 percent of the base metal shall meet the includes the following statement: "In applying the acceptance design analysis requirements of Q-3000. standards, wall thickness, shall be the thickness of 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 Pressure Testing (h) The completed repair shall be pressure tested in accordance The pressure testing requirements included in the alternative are with IWA-5000. A system hydrostatic test is required if the flaw similar to paragraph (h) of ASME Code Case N-504-4 except that penetrated the pressure boundary. A system leakage test may be only a system leakage test per IWA-5000 is required.

performed if pressure boundary is not penetrated.

BSEP 17-0033 Enclosure 2 Page 1 of 3 List of Regulatory Commitments The following table identifies the actions in this document to which the Brunswick Steam Electric Plant (BSEP) has committed. Statements in this submittal, with the exception of those in the table below, are provided for information purposes and are not considered commitments.

Please direct questions regarding these commitments to Mr. Lee Grzeck, Manager - Regulatory Affairs, at (910) 457-2487.

SCHEDULED ONE-TIME CONTINUING COMMITMENT DESCRIPTION COMPLETION ACTION COMPLIANCE DATE Summaries of the results of the analyses of the following will be submitted to the NRC:

1. The as-built dimension of the full structural weld overlay (FSWOL) shall be measured Prior to entry into and evaluated to demonstrate Mode 2 following that they equal or exceed the completion of the minimum design dimensions of FSWOL.

the overlay design.

2. Overall component shrinkage will be measured after the weld overlay application.

The following items will be performed and submitted to the NRC:

1. Nozzle specific stress analyses will be performed to establish a residual stress profile in the N9 nozzle. Inside diameter (ID) weld repairs will be assumed in these analyses Submit this to effectively bound any actual analysis within weld repairs that may have 90 days of occurred in the nozzle. The completing the analysis shall then simulate BSEP Unit 2 application of the FSWOL to refueling outage determine the final residual B223R1.

stress profile. Post weld overlay residual stresses at normal operating conditions will be shown to result in an improved stress state at the ID of the N9 nozzle weld region that reduces the probability for

BSEP 17-0033 Enclosure 2 Page 2 of 3 SCHEDULED ONE-TIME CONTINUING COMMITMENT DESCRIPTION COMPLETION ACTION COMPLIANCE DATE further crack propagation due to stress corrosion cracking (SCC).

2. The analyses will demonstrate that the application of the FSWOL satisfies all ASME Code,Section III stress and fatigue criteria shall be met for the regions of the overlays remote from observed, or assumed, cracks.

3. Fracture mechanics analyses will be performed to predict crack growth. Crack growth due to SCC and fatigue crack growth in the original dissimilar metal weld (DMW) shall be evaluated. These crack growth analyses will consider all design loads and transients, plus the post weld overlay through-wall residual stress distributions, and will demonstrate that the assumed cracks shall not grow beyond the design bases for the weld overlay (i.e., through the original DMW thickness and any additional allowance for crack growth within the weld overlay) for the time period until the next scheduled inservice inspection. The crack growth analyses will determine amount of growth for the assumed cracks to grow over the entire intended service life of the weld overlay.

4. The total added weight on the piping system due to the overlay will be evaluated for the potential impact on reactor pressure vessel nozzle

BSEP 17-0033 Enclosure 2 Page 3 of 3 SCHEDULED ONE-TIME CONTINUING COMMITMENT DESCRIPTION COMPLETION ACTION COMPLIANCE DATE stresses and dynamic characteristics.

The following information will be submitted to the NRC:

1. A listing of indications detected in the overlaid weld. Within 14 days of completion of the

2. The disposition of all final ultrasonic indications using the testing acceptance criteria of ASME examination of Code,Section XI, IWB-3514-2 the overlaid and/or IWB-3514-3 criteria welds.

and, if possible, the type and nature of the indications.