NMP1L3563, Submittal of Relief Request I5R-12, Revision 0, Concerning the Installation of a Full Structural Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld (32-WD-208)

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Submittal of Relief Request I5R-12, Revision 0, Concerning the Installation of a Full Structural Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld (32-WD-208)
ML23338A232
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 12/04/2023
From: David Gudger
Constellation Energy Generation
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
NMP1L3563
Download: ML23338A232 (1)
v • d • e


Text

200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com 10 CFR 50.55a NMP1L3563 December 4, 2023 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-63 NRC Docket No. 50-220

Subject:

Submittal of Relief Request I5R-12, Revision 0, Concerning the Installation of a Full Structural Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld (32-WD-208)

References:

1) Email from R. Guzman (U.S. Nuclear Regulatory Commission) to T. Loomis (Constellation Energy Generation, LLC), Verbal Authorization for NMP1 Proposed Alternative Weld Overlay N2E Safe-end to nozzle DM Weld (EPID L-2023-LLR-0011), dated March 31, 2023 (ML23090A130)
2) Email from R. Guzman (U.S. Nuclear Regulatory Commission) to T.

Loomis (Constellation Energy Generation, LLC), Verbal Authorization for NMP1 Relief Request I5R-14 Proposed Alternative Associated with N2E Safe-End-to-Nozzle DM Weld Repair with a Laminar Indication (EPID L-2023-LLR-0017), dated April 14, 2023 (ML23104A347)

3) Letter from D. Gudger (Constellation Energy Generation, LLC) to U.S.

Nuclear Regulatory Commission, 60 Day Commitment Response - Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld (32-WD-208), dated June 9, 2023 (ML23160A292)

4) Letter from H. Gonzalez (U.S. Nuclear Regulatory Commission) to D.

Rhoades (Constellation Energy Generation, LLC), Nine Mile Point Nuclear Station, Unit No. 1 - Authorization and Safety Evaluation for Alternative Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-To-Nozzle Dissimilar Metal Weld (EPID: L-2023-LLR-0011), dated June 22, 2023 (ML23156A682)

Relief Request I5R-12, Rev. 0 December 4, 2023 Page 2

5) Letter from H. Gonzalez (U.S. Nuclear Regulatory Commission) to D.

Rhoades (Constellation Energy Generation, LLC), Nine Mile Point Nuclear Station, Unit No. 1 - Authorization and Safety Evaluation for Alternative Relief Request I5R-14 Associated with N2E Safe End-To-Nozzle Dissimilar Metal Weld Repair with Laminar Indication (EPID:

L-2023-LLR-0017), dated June 22, 2023 (ML23156A683)

In accordance with 10 CFR 50.55a, Codes and standards, paragraph (z)(1), Constellation Energy Generation, LLC (CEG) requests approval of the attached proposed alternative associated with the repair of the recirculation inlet nozzle N2E safe end-to-nozzle dissimilar metal (DM) weld. The fifth 10-year ISI interval for Nine Mile Point Nuclear Station, Unit 1 (NMP1) began on August 23, 2019, and will conclude on August 22, 2029. The fifth 10-year ISI interval complies with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 2013 Edition.

During the 2023 refueling outage (N1R27), NMP1 identified an unacceptable flaw indicative of Intergranular Stress Corrosion Cracking (IGSCC) in the N2E safe end-to-nozzle DM weld (32-WD-208). CEG repaired this flaw with a leakage barrier weld overlay in N1R27. In the Reference 1 email, the U.S. Nuclear Regulatory Commission (NRC) approved this leakage barrier weld overlay repair for one cycle of operation. Reference 4 provided the authorization and Safety Evaluation Report. As a result, CEG intends to repair the DM weld by installing a full structural weld overlay (FSWOL) over the existing leakage barrier weld overlay using an alternative based on the requirements of ASME Code Case N-740-2.

CEG requests approval of the proposed alternative by June 28, 2024, for the remainder of the current operating license.

A summary of the regulatory commitments contained in this submittal is provided in .

If you have any questions concerning this letter, please contact Tom Loomis at (267) 533-5669.

Respectfully, David T. Gudger Senior Manager - Licensing & Regulatory Affairs Constellation Energy Generation , LLC

Attachment:

1) Summary of Commitments
2) Relief Request I5R-12
3) Review of ASME Code Case N-740-2 against the Proposed Alternative Weld Overlay cc: Regional Administrator, Region I, NRC NRC Senior Resident Inspector, NMP Project Manager NRC, NMP A. L. Peterson, NYSERDA

ATTACHMENT 1 Summary of Commitments

ATTACHMENT 1

SUMMARY

OF COMMITMENTS COMMITMENT TYPE COMMITTED COMMITMENT DATE OR ONE-TIME Programmatic OUTAGE ACTION (Yes/No)

(Yes/No)

Constellation Energy Generation, LLC (CEG) Within 90 days Yes No commits to providing the following information to following the the NRC: end of refueling outage N1R28.

1. A listing of indications detected in the full structural weld overlay material.
2. A description of any repairs to the full structural weld overlay material and the reason for the repair.
3. The disposition of all indications using the acceptance standards of ASME Code,Section XI, IWB-3514.
4. A summary of the residual stress, crack growth analysis and ASME Code,Section III evaluation.

ATTACHMENT 2 Nine Mile Point Nuclear Station, Unit 1 Proposed Alternative for Installation of a Full Structural Weld Overlay (FSWOL)

Repair on the Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld RELIEF REQUEST I5R-12, Revision 0

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 1 of 41)

Proposed Alternative for Installation of a Full Structural Weld Overlay (FSWOL)

Repair on the Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld in Accordance with 10 CFR 50.55a(z)(1) 1.0 ASME CODE COMPONENT(S) AFFECTED Code Class: 1

Reference:

ASME Code Case N-716-1 & BWRVIP-75-A, Category D Examination Category: R-A Item Number: R1.16, Welds Subject to IGSCC

Description:

Reactor Pressure Vessel (RPV) Recirculation Inlet Nozzle N2E Safe End-to-Nozzle DM Weld Materials: Nozzle - SA-336 with buttering Weld Material - Alloy 82/182 (UNS N06082/W86182)

Safe End - SA-182 F316 Leakage Barrier Weld Overlay Material - Alloy 52M Size: Nominal 29 Inches (Outer Diameter)

Component Number(s): Weld No. 32-WD-208 Drawing Numbers: ISI-NOZ-002 2.0 APPLICABLE CODE EDITION AND ADDENDA The fifth interval of the Nine Mile Point Nuclear Station, Unit 1 Inservice Inspection (ISI) Program is based on the American Society of Mechanical Engineers (ASME)

Boiler and Pressure Vessel (B&PV) Code,Section XI, 2013 Edition. The fifth ISI interval began on August 23, 2019, and is scheduled to conclude on August 22, 2029.

3.0 APPLICABLE CODE REQUIREMENTS IWA-4411 of the ASME Code,Section XI states that 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, that 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).

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 2 of 41)

IWA-4411(b) of the ASME Code,Section XI states that Revised Owners Requirements may be used, provided they are reconciled in accordance with IWA-4222.

IWA-4412 states: Defect removal shall be accomplished in accordance with the requirements of IWA-4420.

IWA-4611 specifies requirements for defect removal and examination following defect removal.

4.0 REASON FOR REQUEST Dissimilar metal (DM) welds containing nickel welding Alloys 82 and 182 have experienced Intergranular Stress Corrosion Cracking (IGSCC) in components operating in boiling water reactors (BWRs).

On March 18, 2023, during automated encoded UT examination of the N2E safe end-to-nozzle DM weld (32-WD-208), one relevant indication was recorded. The indication was determined to be axially oriented and located in the DM weld and adjacent safe end material. The indication is located approximately 14 inches clockwise from top of center. The indication is inner diameter connected with attributes that are indicative of IGSCC.

This flaw did not meet the acceptance standards of IWB-3500 and could not be accepted by analytical evaluation in accordance with IWB-3600; therefore, a repair/replacement activity was required in accordance with IWA-4000.

A repair for this flaw was approved in References 9 and 10. A summary report of the repair was provided in the Reference 11 letter.

After installation of the leakage barrier weld overlay, ultrasonic examination in N1R27 showed that the initial flaw had relieved to the interface of the original Alloy 82/182 weld and the Alloy 82 bridge beads applied during installation of the leakage barrier weld overlay. The final indication parameters were as follows:

Thickness at Flaw: 2.28 Axial Length: 1.65 Flaw Depth: 1.69 Remaining Ligament: 0.59 Location: Weld/Adjacent Safe End Material Constellation Energy Generation, LLC (CEG) proposes to perform a repair of the Nine Mile Point, Unit 1 (NMP1) Reactor Recirculation Inlet Nozzle N2E Safe-End-to-Nozzle DM weld by installing a FSWOL using the guidance of ASME Code Case N-740-2 for the remainder of the current license period.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 3 of 41)

The Edition of ASME Code,Section XI applicable to NMP1 (2013 Edition) does not contain requirements for nickel alloy weld overlays; however, nickel alloy weld overlay repairs have been applied to other RPV nozzle DM welds in boiling water reactors (BWRs) using alternative requirements. This request proposes to use the guidance in ASME Code Case N-740-2 for application of a FSWOL on the N2E Safe End-to-Nozzle DM weld at NMP1. Because ASME 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 proposed alternative describes the requirements that CEG proposes to use to design and install a FSWOL on the N2E Safe End-to-Nozzle DM weld.

During N1R27, a leakage barrier weld overlay was completed using machine GTAW with Alloy 52M filler material. The ambient temperature temper bead method with ERNiCrFe-7A weld metal (referred to as Alloy 52M in subsequent discussion in this document) was applied to the carbon steel nozzle. Alloy 82 was used for the bridge beads over the original weld material and ER309L was used for sulfur mitigation on the stainless steel safe end. The length of the leakage barrier weld overlay installed during N1R27 is sufficient to satisfy the FSWOL axial length required by Code Case N-740-2. An estimated 0.26 of weld overlay will be added during N1R28 to complete the 0.76 minimum design thickness for the full structural weld overlay thickness. The additional weld overlay will be installed using machine GTAW with Alloy 52M filler material to complete the FSWOL.

During N1R27 there were 3 laminar flaws identified in the final volumetric examination of the leakage barrier weld overlay as described in Reference 11. Two of the three laminar flaws were acceptable per N-740-2. The third laminar indication was accepted per Non-Mandatory Appendix Q in Relief Request I5R-14 (Reference 12).

It is proposed to continue with the ASME Section XI Non-Mandatory Appendix Q laminar flaw acceptance criteria for the volumetric examinations of the existing and final FSWOL.

5.0 PROPOSED ALTERNATIVE AND BASIS FOR USE Pursuant to 10 CFR 50.55a(z)(1), CEG proposes an alternative to the ASME Code requirements stated in Section 3.0 to allow the installation of a weld overlay over the existing repair that will ensure the continued leak-tightness and structural integrity of this weld. The proposed repair will be installed prior to the return to service from refueling outage N1R28.

CEG plans to apply an Alloy 52M FSWOL over the dissimilar metal Alloy 82/182 weld and the existing leakage barrier weld overlay. The FSWOL will be designed in accordance with the guidance of ASME Code Case N-740-2, as detailed in this request. Attachment 3 provides a comparison of the proposed alternative to ASME Code Case N-740-2, and provides additional technical justifications for the alternative.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 4 of 41)

CEG requests approval of the FSWOL for the remainder of the current license period.

5.1 Description of Weld Overlay 5.1.1. Overview CEG proposes the following detailed requirements for the design, analysis, fabrication, examination, and pressure testing of the NMP1 Reactor Recirculation Inlet Nozzle N2E dissimilar metal weld FSWOL. These requirements, which are derived from applicable portions of ASME Code Case N-740-2, will provide an acceptable methodology for providing a repair that will eliminate the risk of through-wall leakage or loss of structural integrity that could result from continued growth of the IGSCC initiated flaw identified in Section 4.0 of this request.

The weld overlay will be applied by deposition of weld reinforcement (i.e., weld overlay) on the outside surface of the nozzle, safe end, associated dissimilar metal weld, and existing leakage barrier weld overlay, in accordance with the following requirements:

5.1.2 GENERAL REQUIREMENTS (Correlated to N-740-2, paragraph 1) 5.1.2.1 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.

(b) SCC susceptible materials - For this proposed alternative, the stress corrosion cracking (SCC) susceptible materials are Unified Numbering System (UNS)

N06600, W86182, or austenitic stainless steels in boiling water reactor environments.

5.1.2.2 General Overlay Requirements (a) A full-structural weld overlay shall be applied by deposition of weld reinforcement (i.e., weld overlay) on the outside surface of the circumferential leakage barrier weld overlay. This proposed method applies to austenitic nickel alloy and austenitic stainless steel welds between P-No. 8 and P-No. 3 materials.

(b) The weld overlay shall not obstruct a required examination of an adjacent P-No. 8 to P-No. 8 weld.

(c) Weld overlay filler metal shall be austenitic nickel alloy (i.e., 28 percent chromium minimum, ERNiCrFe-7/7A) meeting the requirements of this alternative, and shall be applied 360 degrees around the circumference of the

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 5 of 41) 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.

The weld filler metal to be used in the weld overlay is ERNiCrFe-7A (Alloy 52M).

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

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

(2) If weld repair of indications is required, the area where the weld overlay is to be deposited, including any local weld repairs or initial weld overlay layer, shall be examined by the liquid penetrant method. The area shall contain no indications with major dimensions greater than 1/16 inch (i.e.,

1.5 millimeters) prior to application of the structural layers of the weld overlay.

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

5.1.2.2(d)(1) and (3) were completed during installation of the leakage barrier weld overlay and are not applicable to the additional structural layers. ER309L was used and deposited using the GTAW welding process. The requirement of 5.1.2.2(d)(2) shall also apply to the existing Alloy 52M leakage barrier weld overlay and additional weld metal deposited to complete the FSWOL.

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

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

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 6 of 41) determined by chemical analysis of the production weld or of a representative coupon taken from a mockup prepared in accordance with the WPS for the production weld.

(f) This alternative shall only be used 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.

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

The FSWOL will be installed on top of the existing leakage barrier weld overlay.

The existing leakage barrier weld overlay will be volumetrically examined prior to application of additional layers of Alloy 52M weld metal. Volumetric examination will also confirm the laminar flaw that was accepted per Non-Mandatory Appendix Q in Relief Request I5R-14 (Reference 12) remains acceptable per Non-Mandatory Appendix Q.

Additionally, the existing weld overlay will receive a surface examination as described in 5.1.2.2(d) to ensure the acceptability of the existing weld overlay for continued welding. Upon volumetric and surface examinations of the existing leakage barrier weld overlay, the FSWOL will be completed by installing additional weld layers as necessary.

The intent of this requirement is to prevent a leaking weld overlay from being repaired with a second weld overlay. Volumetric and surface examinations will confirm the integrity of the leakage barrier weld overlay prior to installing the remaining weld layers needed to complete the FSWOL.

CEG does not plan to remove the existing leakage barrier weld overlay because this may result in a reactor coolant system leak. Ultrasonic examination during outage N1R27 showed that the initial flaw had relieved to the interface of the original Alloy 82/182 weld and the Alloy 82 bridge beads applied during installation of the leakage barrier weld overlay.

Prior to depositing the additional Alloy 52M filler material on the existing leakage barrier weld overlay, procedurally approved cleaning methods will be performed to ensure clean weld material for welding.

5.1.3 CRACK GROWTH AND DESIGN (Correlated to N-740-2, paragraph 2)

(a) Crack Growth Calculation of Flaws in the Original Weld or Base Metal.

The size of the flaw detected or postulated in the original weld or base metal shall be used to define the life of the overlay. The inspection interval shall not be longer than the shorter of the life of the overlay or the period specified in 5.1.4(c). Crack growth due to both stress corrosion and fatigue shall be evaluated. Flaw characterization and evaluation shall be based on the

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 7 of 41) examination results or postulated flaw, as described below. If the flaw is at or near the boundary of two different materials, evaluation of flaw growth in both materials is required.

The initial flaw size to be used in determining the life of the overlay is documented in Section 1.0 of this request. If, during the preservice examinations performed in accordance with this alternative, the flaw size is found to be larger than that documented in Section 1.0 of this request, the larger flaw size shall be used to determine the life of the FSWOL.

Ultrasonic examination of the leakage barrier weld overlay in N1R27 showed that the initial flaw had relieved to the interface of the original Alloy 82/182 weld and the Alloy 82 bridge beads applied during installation of the leakage barrier weld overlay. Volumetric and surface examinations will confirm the integrity of the leakage barrier weld overlay prior to installing the remaining weld layers needed to complete the FSWOL. Following the completion of the FSWOL, preservice inspections will be performed on the entire weld overlay volume including the initial flaw found in the base material during N1R27. These flaw dimensions will be used to determine the life of the FSWOL.

(b) Structural Design and Sizing of the Overlay.

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

(1) The axial length and end slope of the weld overlay shall cover the weld and heat-affected zones on each side of the weld, as well as any SCC-susceptible base material adjacent to the weld and provide for load redistribution from the item into the weld overlay and back into the item without violating the applicable stress limits of NB-3200. Any laminar flaws in the weld overlay shall be evaluated in the analysis to ensure that load redistribution complies with the above. These requirements 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).

(2) Unless specifically analyzed in accordance with (1), the end transition slope of the overlay shall not exceed 30 deg.

The end transition slope of the FSWOL shall not exceed 45 deg., and the FSWOL will be analyzed for this transition slope.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 8 of 41)

(3) The required thickness of the FSWOL shall be based on an assumed flaw in the underlying base material or weld that is a 100 percent through-wall circumferential flaw for the entire circumference.

(4) The overlay design thickness shall be verified, using only the weld overlay thickness conforming to the deposit analysis requirements. 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, shall be evaluated and shall meet the requirements of IWB-3640.

(5) The effects of any changes in applied loads, as a result of weld shrinkage from the entire overlay, on other items in the piping system (e.g., support loads and clearances, nozzle loads, and changes in system flexibility and weight due to the weld overlay) shall be evaluated. Existing flaws previously accepted by analytical evaluation shall be evaluated in accordance with IWB-3640.

5.1.4 EXAMINATION (Correlated to N-740-2, paragraph 3)

In lieu of all other examination requirements, the following examination requirements shall be met for the life of the overlay.

  • Ultrasonic examination shall 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 shall 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 shall have a surface finish of 250 micro-inches (-in)

RMS or better and contour that permits ultrasonic examination in accordance with procedures qualified in accordance with ASME Code Case N-653-2. The weld overlay shall be inspected to verify acceptable configuration.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 9 of 41)

(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 shall be examined using the liquid penetrant method. The weld overlay shall satisfy the surface examination acceptance criteria for welds of the Construction Code or NB-5300. The adjacent base material shall satisfy the surface examination acceptance criteria for base material of the Construction Code or NB-2500.

If ambient temperature temper bead welding is performed, the liquid penetrant examination of the completed weld overlay shall be conducted no sooner than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> following completion of the three tempering layers over the ferritic steel.

Ambient temperature temper bead welding is not required for completion of the FSWOL in N1R28, as the additional Alloy 52M layers will be applied on the existing Alloy 52M leak barrier weld overlay; therefore, the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold is not required.

(3) The examination volume A-B-C-D in Figure 1(a), shown below, shall be ultrasonically examined to assure adequate fusion (i.e., adequate bond) with the base material and to detect welding flaws, such as interbead lack of fusion, inclusions, or cracks. The interface C-D shown between the overlay and weld includes the bond and heat-affected zone from the overlay. If ambient temperature temper bead welding is performed, the ultrasonic examination shall be conducted no sooner than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> following completion of the three tempering layers over the ferritic steel.

Planar flaws detected in the weld overlay acceptance examination shall meet the preservice examination standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness, t1 or t2 defined in Figure 1(b), shown below, shall be used as the nominal wall thickness in IWB-3514, provided the base material beneath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to 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) shall be used. Laminar flaws in the weld overlay shall meet the following requirements:

(-a) The acceptance standards of IWB-3514 shall be met.

(-b) For examination volume A-B-C-D in Figure 1(a), shown below, the reduction in coverage due to laminar flaws shall 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 shall be assumed to contain the largest radial planar flaw that could exist within that volume. This assumed flaw shall meet the preservice examination acceptance standards of IWB-3514, with nominal wall thickness as

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 10 of 41) defined above the planar flaws. Alternatively, the assumed flaw shall be evaluated and meet the requirements of IWB-3640. Both axial and circumferential planar flaws shall 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.

Notes:

1. Dimension b is 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 scan two examination volumes (such as illustrated in F-G) the t1 thickness shall be used.
4. The weld includes the nozzle or safe end butter, where applied, plus any SCC-susceptible base material in the nozzle.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 11 of 41)

(b) Preservice Inspection.

(1) The examination volume in Figure 2, shown below, shall be ultrasonically examined. The angle beam shall be directed perpendicular and parallel to the piping axis, with scanning performed in four directions, to locate and size any planar flaws that have propagated into the outer 25 percent of the base metal thickness or into the weld overlay.

Ultrasonic examination of the leakage barrier weld overlay in N1R27 showed that the initial flaw had relieved to the interface of the original Alloy 82/182 weld and the Alloy 82 bridge beads applied during installation of the leakage barrier weld overlay.

(2) The preservice examination acceptance standards of IWB-3514 shall be met for the weld overlay. In applying the acceptance standards to planar indications, the thickness, t1 or t2, defined in Figure 1(b), shall be used as the nominal wall thickness in IWB-3514, provided the base material beneath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to SCC. For susceptible material, t1 shall be used. Planar flaws in the outer 25 percent of the base metal thickness shall meet the design analysis requirements of 5.1.3(b).

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

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.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 12 of 41)

(c) Inservice Inspection.

(1) The weld overlay examination shall be added to the inspection plan.

The weld overlay inspection interval shall not be greater than the life of the overlay as determined above. All weld overlays shall be examined prior to the end of their design life.

(2) The weld overlay examination volume in Figure 2 shall be ultrasonically examined during the first or second refueling outage following application.

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

Ultrasonic examination of the leakage barrier weld overlay in N1R27 showed that the initial flaw had relieved to the interface of the original Alloy 82/182 weld and the Alloy 82 bridge beads applied during installation of the leakage barrier weld overlay.

(4) The weld overlay shall meet the inservice examination acceptance standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness, t1 or t2 , defined in Figure 1(b), shall be used as the nominal wall thickness in IWB-3514, provided the base material beneath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to SCC. For susceptible material, t1 shall be used. If the acceptance standards of IWB-3514 cannot be met, the weld overlay shall meet the acceptance standards of IWB-3600. If a planar flaw is detected in the outer 25% of the base material thickness, the overlay shall meet the design analysis requirements of 5.1.3. Any indication characterized as stress corrosion cracking in the weld overlay material is unacceptable.

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

This requirement does not apply to the FSWOL in this request because the Unit 1 operating license will expire at the end of the current inspection interval on August 22, 2029.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 13 of 41)

(6) If inservice examinations reveal planar flaw growth, or new planar flaws, meeting the acceptance standards of IWB-3514 or IWB-3600, the weld overlay examination volume shall 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 5.1.4(c)(4), the weld overlay and original defective weld shall be removed. A repair/replacement activity shall be performed in accordance with IWA-4000.

(d) Additional Examinations.

If inservice examinations reveal a defect, in accordance with 5.1.4(c)(4) above, planar flaw growth into the weld overlay design thickness, or axial flaw growth beyond the specified examination volume, additional weld overlay examination volumes, equal to the number scheduled for the current inspection period, shall be examined prior to return to service. If additional defects are found in the second sample, 50% of the total population of weld overlay examination volumes shall be examined prior to return to service. If additional defects are found, the entire remaining population of weld overlay examination volumes shall be examined prior to return to service.

5.1.5 PRESSURE TESTING A system leakage test and VT-2 visual examination shall be performed on the weld overlay in accordance with IWA-5000 following completion of the weld overlay and acceptance examinations.

IWA-5214 requires a preservice system pressure test following repair/replacement activities in accordance with IWA-4540. IWA-4540(b)(3) exempts welding or brazing that does not penetrate through the pressure boundary from a pressure test and VT-2 examination. The FSWOL does not penetrate through the full thickness of the pressure boundary and is therefore exempt from the pressure testing requirements of IWA-4540.

However, the FSWOL is within the boundary of IWB-5222(a) and will be subject to pressurization and VT-2 examination as part of the Class 1 system leakage test prior to return to service.

5.1.6 DOCUMENTATION Use of this proposed method shall be documented on Form NIS-2.

5.1.7 AMBIENT-TEMPERATURE TEMPER BEAD WELDING As an alternative to the requirement of IWA-4411 to perform repairs in accordance with the Construction Code, which would require post weld heat treatment for these materials, ambient temperature temper bead welding shall be performed in

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 14 of 41) accordance with ASME Code Case N-638-10, which has been approved for use in Table 1 of Regulatory Guide 1.147, Revision 20.

The carbon steel nozzle ambient temperature temper bead layers were installed during N1R27, in accordance with Code Case N-638-10 as described in I5R-11 Revision 0.

Ambient temperature temper bead welding is not required for completion of the FSWOL in N1R28. Any additional heat input from completion of the FSWOL in N1R28 will have no adverse effect on the carbon steel nozzle base material.

5.1.8 WELD OVERLAY DESIGN INFORMATION (a) Schematic Configuration for the Weld Overlay.

A representation of the weld overlay configuration for the N2E nozzle weld 32-WD-208 is presented schematically in Figure 3, below.

(b) RPV Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld.

The RPV Recirculation Inlet Nozzle N2E is fabricated from SA-336 low alloy steel. The nozzle-to-safe end buttering and weld are made using Alloy 82/182 weld material, and the safe end material is SA-182, F316.

Additional overlay material to be installed to complete the FSWOL Existing leakage barrier weld overlay Figure 3 Schematic Configuration for the N2E Nozzle with Weld Overlay Note: The above figure is not drawn to scale and does not accurately reflect the relative thickness of the FSWOL to the DM weld thickness.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 15 of 41)

(c) Suitability of Proposed Post Overlay Nondestructive Examination (NDE).

As part of the design of the weld overlay, the length, surface finish, and end transition specified will allow for post-installation UT examinations qualified in accordance with ASME Code Case N-653-2 to be performed. These examinations include the weld overlay and the required volume of the base material and original weld underneath the overlay.

The examinations specified in this proposed alternative provide adequate assurance that the overlay was installed correctly and can ensure the structural and leak-tight integrity of the nozzle-to-safe end weld for the following reasons:

  • The UT examinations will be performed with the proposed alternative ASME Code Case N-653-2 in lieu of the requirements of Appendix VIII, Supplement 11. Examinations performed using these requirements can be used to assess service-induced and fabrication-induced flaws. It is applicable for wrought austenitic, ferritic, or dissimilar metal welds, overlaid with austenitic weld material. ASME Code,Section XI has specific acceptance criteria and evaluation methodology. The criteria considers 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-3514-1) and for laminar flaws (i.e.,

Table IWB-3514-3).

  • A laminar flaw is defined in (IWA-3360) 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 ASME Code,Section XI laminar flaw standards are contained in Table IWB-3514-3 of the ASME Code,Section XI. For weld overlay areas where examination is precluded by the presence of a laminar flaw, the areas must be postulated to be cracked.
  • Any planar flaws found during the weld overlay acceptance and preservice examinations of the weld overlay (excluding the base metal and existing weld) shall meet the preservice examination acceptance standards of ASME Code,Section XI, IWB-3514, as specified in 5.1.4(b)(2).
  • 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.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 16 of 41)

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.

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 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. ASME Code,Section XI Non-Mandatory Appendix Q has been approved by the NRC. 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. ASME Code Case N-740-2 has since been developed for use on DM welds, but the NRC has not yet approved use of this Code Case in Regulatory Guide 1.147.

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

weld overlay procedures that create compressive residual stress profiles within the original weld, and post-overlay preservice and in-service inspection requirements provide assurance that structural integrity will be maintained for the remaining service life of the weld. Crack growth evaluations for SCC and fatigue of a bounding postulated flaw will demonstrate that structural integrity of the component, with the FSWOL in place, will be maintained for the remaining service life of the component.

ASME Code Case N-653-2 specifies alternative requirements to Appendix VIII, Supplement 11 and shall be used for qualification requirements for detection and length and depth sizing of flaws in the overlay. This case is approved for use in Regulatory Guide 1.147 and is documented in the NMP1 Inservice Inspection Program Plan, as required by IWA-2441.

(d) Weld Overlay Design and Evaluation.

(1) The following list of evaluations shall be performed subject to the specific design, analysis, and inspection requirements that have been defined in this proposed alternative.

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

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 17 of 41)

2. CEG is proposing to apply a FSWOL using IGSCC resistant material (Alloy 52M), based on the requirements of ASME Code Case N-740-2.

Guidance in ASME Code Case N-740-2 is being used because the Alloy 52M weld overlay material will be deposited over an existing leakage barrier weld overlay and Alloy 82/182 weldment.

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

(2) The following information shall be submitted to the NRC within 90 days following the end of N1R28:

1. A listing of indications detected in the full structural weld overlay material.
2. A description of any repairs to the full structural weld overlay material and the reason for the repair.
3. The disposition of all indications using the acceptance standards of ASME Code,Section XI, IWB-3514.
4. A summary of the residual stress, crack growth analysis and ASME Code,Section III evaluation.

(e) Additional Information.

CEG notes that the adjacent low alloy steel nozzle-to-vessel weld is inaccessible for examination from the nozzle side of the weld due to the configuration of the weld joint. Installation of the proposed weld overlay will not affect the ultrasonic examination coverage of this weld that can be obtained from the vessel side of the weld.

Based on the requirements for crack growth, structural design and sizing, examination, pressure testing, and preservice and in service examination, the proposed alternative provides assurance that structural and leak-tight integrity will be maintained for the duration of the life of the FSWOL. Therefore, the proposed alternative provides an acceptable level of quality and safety.

The proposed alternative requests to continue deposition of weld material on the existing leakage barrier weld overlay to achieve the required thickness for a FSWOL. The existing leakage barrier weld overlay will be surface and volumetrically examined prior to welding. The same weld method (GTAW) and material (Alloy 52M) will be used. The use of temper bead welding is not required since all required tempering layers were installed in 2023. The

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 18 of 41) deposition of additional weld material will ensure that the design requirements of the FSWOL are met. Increasing the thickness to achieve a FSWOL will reduce the through wall extent of the previously identified flaw and will ensure it is below 75% through wall.

6.0 DURATION OF THE PROPOSED ALTERNATIVE This alternative is proposed for use on the Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld for the remainder of the current operating license.

7.0 PRECEDENTS

1. Email from R. Guzman (U.S. Nuclear Regulatory Commission) to T. Loomis (Constellation Energy Generation, LLC), Verbal Authorization for NMP1 Proposed Alternative Weld Overlay N2E Safe-end to nozzle DM Weld (EPID L-2023-LLR-0011), dated March 31, 2023 (ML23090A130).
2. Email from R. Guzman (U.S. Nuclear Regulatory Commission) to T. Loomis (Constellation Energy Generation, LLC), Verbal Authorization for NMP1 Relief Request I5R-14 Proposed Alternative Associated with N2E Safe-End-to-Nozzle DM Weld Repair with a Laminar Indication (EPID L-2023-LLR-0017), dated April 14, 2023 (ML23104A347).
3. Letter from H. Gonzalez (U.S. Nuclear Regulatory Commission) to D.

Rhoades (Constellation Energy Generation, LLC), Nine Mile Point Nuclear Station, Unit No. 1 - Authorization and Safety Evaluation for Alternative Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-To-Nozzle Dissimilar Metal Weld (EPID: L-2023-LLR-0011), dated June 22, 2023 (ML23156A682).

4. Letter from H. Gonzalez (U.S. Nuclear Regulatory Commission) to D.

Rhoades (Constellation Energy Generation, LLC), Nine Mile Point Nuclear Station, Unit No. 1 - Authorization and Safety Evaluation for Alternative Relief Request I5R-14 Associated with N2E Safe End-To-Nozzle Dissimilar Metal Weld Repair with Laminar Indication (EPID: L-2023-LLR-0017),

dated June 22, 2023 (ML23156A683).

5. A similar relief request to use the guidance of ASME Code Case N-740-2 was previously approved on May 15, 2018 for the Duke Energy Progress Brunswick Steam Electric Plant Unit 1 (ML18124A308).

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 19 of 41)

8.0 REFERENCES

1. ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," 2013 Edition.
2. ASME Code Case N-740-2, Full Structural Dissimilar Metal Weld Overlay for Repair or Mitigation of Class 1, 2, and 3 Items,Section XI, Division 1, dated November 10, 2008.
3. ASME Code Case N-653-2, Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds,Section XI, Division 1, dated June 23, 2015.
4. ASME Code Case N-638-10, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1, dated May 6, 2019 (Corrected by Errata - ASME Record
  1. 19-2617).
5. ASME Code Case N-716-1, Alternative Classification and Examination Requirements,Section XI, Division 1, dated January 27, 2013.
6. Generic Letter 88-01, NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping, January 25, 1988.
7. BWRVIP-75-A: BWR Vessel and Internals Project, Technical Basis for Revisions to Generic Letter 88-01 Inspection Schedules, dated October 2005.
8. BWRVIP-97-A: BWR Vessel and Internals Project, Guidelines for Performing Weld Repairs to Irradiated BWR Internals, dated June 2009.
9. Email from R. Guzman (U.S. Nuclear Regulatory Commission) to T. Loomis (Constellation Energy Generation, LLC), Verbal Authorization for NMP1 Proposed Alternative Weld Overlay N2E Safe-end to nozzle DM Weld (EPID L-2023-LLR-0011), dated March 31, 2023 (ML23090A130).
10. Letter from H. Gonzalez (U.S. Nuclear Regulatory Commission) to D.

Rhoades (Constellation Energy Generation, LLC), Nine Mile Point Nuclear Station, Unit No. 1 - Authorization and Safety Evaluation for Alternative Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-To-Nozzle Dissimilar Metal Weld (EPID: L-2023-LLR-0011), dated June 22, 2023 (ML23156A682).

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 20 of 41)

11. Letter from D. Gudger (Constellation Energy Generation, LLC) to U.S.

Nuclear Regulatory Commission, 60 Day Commitment Response - Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle Dissimilar Metal Weld (32-WD-208), dated June 9, 2023 (ML23160A292).

12. Letter from H. Gonzalez (U.S. Nuclear Regulatory Commission) to D.

Rhoades (Constellation Energy Generation, LLC), Nine Mile Point Nuclear Station, Unit No. 1 - Authorization and Safety Evaluation for Alternative Relief Request I5R-14 Associated with N2E Safe End-To-Nozzle Dissimilar Metal Weld Repair with Laminar Indication (EPID: L-2023-LLR-0017), dated June 22, 2023 (ML23156A683).

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 21 of 41)

ATTACHMENT 3 Review of ASME Code Case N-740-2 against the Proposed Alternative Weld Overlay Included in Exceptions to N-740-2 ASME Code Case N-740-2 Requirement Proposed Justification (highlighted in bold)

Alternative

1. GENERAL REQUIREMENTS 1.1 DEFINITION (a) Full Structural Weld Overlay. Deposition of weld Yes N/A 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 (b) and (c).

(b) Mitigative Weld Overlay. Weld overlay that is applied No Definition does not apply to proposed N/A over material with no inside surface connected flaws found alternative.

during an examination performed in accordance with 2(a)(3), prior to the weld overlay being applied.

(c) Repair Weld Overlay. Weld overlay that is applied over No Definition does not apply to proposed N/A material with an inside surface connected flaw or subsurface alternative.

defect, or where a pre-weld overlay examination is not performed.

(d) SCC Susceptible Materials. For this Case, the stress- Yes The referenced BWR materials, UNS N/A corrosion-cracking (SCC) susceptible materials are UNS N06082 and W86182, are also recognized N06600, N06082, or W86182 in PWR environment; or UNS as susceptible materials in ASME Code, N06600, W86182, or austenitic stainless steels and Section XI, 2013 Edition.

associated welds in BWR environments.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 22 of 41)

Included in Exceptions to N-740-2 ASME Code Case N-740-2 Requirement Proposed Justification (highlighted in bold)

Alternative 1.2 GENERAL OVERLAY REQUIREMENTS (a) A full-structural weld overlay shall be applied by Yes 32-WD-208 is a dissimilar metal weld The alternative is used deposition of weld reinforcement (weld overlay) on the between the SA-336 (P-No. 3) N2E nozzle only for P-No. 8 to P-No.

outside surface of circumferential welds. This Case applies and the SA-182 F316 (P-No.8) safe end 3 materials.

to austenitic nickel alloy and austenitic stainless-steel made with Alloy 82/182 filler metal which welds between the following: meets the material requirements of ASME Code Case N-740-2. The Case was (1) P-No. 8 or P-No. 43 and P-Nos. 1, 3, 12A, 12B, or specifically written to address the 12C1 applicable of weld overlays over dissimilar (2) P-No. 8 and P-No. 43 metal welds and austenitic stainless steel welds.

(3) Between P-Nos. 1, 3, 12A, 12B, and 12C 1 materials (b) If a weld overlay on any of the material combinations in No The adjacent safe end-to-pipe weld (32- The weld overlay is not (a) obstructs a required examination of an adjacent P-No. 8 WD-207) is a Category R-A, Item No. being extended to to P-No. 8 weld, the overlay may be extended to include R1.20 (no degradation mechanism) include the adjacent overlaying the adjacent weld. component in the RI-ISI program. There weld.

is no requirement in the RI-ISI program that this component be examined, and it is not currently included in the RI-ISI program examination scope. Therefore, the weld overlay will not be extended to include the adjacent weld.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 23 of 41)

Included in Exceptions to N-740-2 ASME Code Case N-740-2 Requirement Proposed Justification (highlighted in bold)

Alternative (c) Weld overlay filler metal shall be austenitic nickel alloy Yes The weld filler metal and procedure Ambient temperature (28% Cr min., ERNiCrFe-7/7A) meeting the requirements of requirements of N-740-2 are equivalent to temper bead welding is (e)(1) or (e)(2), as applicable, applied 360 deg around the ASME Code,Section XI, Appendix Q, not required for circumference of the item and deposited using a Welding which is accepted for use by the NRC. completion of the Procedure Specification (WPS) for groove welding, qualified FSWOL in N1R28, as The weld overlay shall be deposited with in accordance with the Construction Code and Owner's there will be no welding ERNiCrFe-7A (Alloy 52M) filler metal Requirements identified in the Repair/Replacement Plan. As on the nozzle base which has excellent resistance to stress an alternative to the post weld heat treatment (PWHT) material.

corrosion cracking as documented in EPRI requirements of the Construction Code and Owner's Technical Report MRP-115, Section 2.2.

requirements, the provisions of Mandatory Appendix I The WPS used for depositing the weld may be used for ambient-temperature temper bead overlay is qualified as a groove welding welding. procedure to ensure that mechanical properties of the WPS are appropriately established. Where welding was performed on the ferritic nozzle material, an ambient temperature temper bead WPS was used.

(1) For P-No. 1 base materials, the Construction No This requirement is not applicable and is N/A Code PWHT exemptions permitted for circumferential not used in the proposed alternative butt welds may be applied to exempt the weld overlay because the FSWOL will not be installed from PWHT, with the following clarifications: over P-No. 1 base materials.

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

(-b) The base material thickness is defined as the maximum thickness of the ferritic material where the overlay is applied.

(2) If ambient-temperature temper bead welding No Ambient temperature temper bead welding is used, Mandatory Appendix I shall be used. is not required for completion of the FSWOL in N1R28.

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 24 of 41)

Included in Exceptions to N-740-2 ASME Code Case N-740-2 Requirement Proposed Justification (highlighted in bold)

Alternative (d) Prior to deposition of the weld overlay, the surface Yes The requirements for examination prior to N/A to be weld overlaid shall be examined using the liquid deposition of the weld overlay in N-740-2 penetrant method. Indications with major dimensions are equivalent to ASME Code,Section XI, greater than 1/16 in. (1.5 mm) shall be removed, reduced Non-Mandatory Appendix Q, Q-2000 in size, or weld repaired in accordance with the which has been accepted for use by the following requirements: NRC.

(1) One or more layers of weld metal shall be No During installation of the leakage barrier N/A applied to seal unacceptable indications in the area to weld overlay, sacrificial layers were be repaired with or without excavation. The thickness of installed to seal any unacceptable these layers shall not be used in meeting weld indications in the base material. Any reinforcement design thickness requirements. Peening unacceptable PT indications in the the unacceptable indication prior to welding is leakage barrier weld overlay, prior to permitted. installation of the additional FSWOL layers, will be repaired in accordance with (d)(2), below.

(2) If weld repair of indications identified in (d) is Yes The requirements for examination prior to N/A required, the area where the weld overlay is to be deposition of the weld overlay in N-740-2 deposited, including any local weld repairs or initial are equivalent to ASME Code,Section XI, weld overlay layer, shall be examined by the liquid Non-Mandatory Appendix Q, Q-2000 penetrant method. The area shall contain no indications which has been accepted for use by the with major dimensions greater than 1/16 in. (1.5 mm) prior NRC.

to application of the structural layers of the weld overlay.

(3) To reduce the potential of hot cracking when No During installation of the leakage barrier N/A applying an austenitic nickel alloy over P-No. 8 base weld overlay, ER309L buffer layers were metal, it is permissible to apply a layer or multiple layers installed using the GTAW welding process of austenitic stainless steel filler material over the over the SA-182 F316 safe end. The austenitic stainless steel base metal. The thickness of stainless steel filler metal applied had a these layers shall not be used in meeting weld delta ferrite content of 5 to 15 Ferrite reinforcement design thickness requirements. The Number (FN), as reported on the CMTR.

filler material used shall meet the minimum requirements for delta ferrite.

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Included in Exceptions to N-740-2 ASME Code Case N-740-2 Requirement Proposed Justification (highlighted in bold)

Alternative (e) Weld overlay deposits shall meet the following No The requirements of N-740-2(e)(1) are not N/A requirements: applicable because Alloy 52M material will be used for the FSWOL.

(1) 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%.

(2) The austenitic nickel alloy weld overlay shall consist Yes The weld overlay shall be deposited with Alternative requirements of at least two weld layers deposited using a filler material ERNiCrFe-7A (Alloy 52M) filler metal for crediting the dilution with a Cr content of at least 28%. The first layer of weld metal which has excellent resistance to stress layer for PWRs will not deposited may not be credited toward the required thickness. corrosion cracking as documented in EPRI be used.

Alternatively, for PWR applications, a first diluted layer Technical Report MRP-115, Section 2.2.

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

10 CFR 50.55a Proposed Alternative I5R-12 Revision 0 (Page 26 of 41)

Included in Exceptions to N-740-2 ASME Code Case N-740-2 Requirement Proposed Justification (highlighted in bold)

Alternative (f) This Case is only for welding in applications Yes The N2E nozzle is located in the lower N/A predicted not to have exceeded thermal neutron (E < 0.5 head of the reactor vessel well below the eV) fluence of 1 x 1017 neutrons per cm 2 prior to welding. beltline region (high fluence region). The projected accumulated EFPY for NMP1 is 42.2. For the N1 nozzles, which are above the N2E nozzle and also below the beltline region, the fast neutron fluence value (E>1.0 MeV) projected at 46 EFPY at the inside diameter (0T) of the vessel is 7.39 E+16 neutron/cm2 for the N1 nozzle closest in azimuth to the N2E nozzle. This value is below the threshold level of 1E+17 neutron/cm2 (E > 1.0 MeV) and as such the material in the area of this repair is not expected to have decreased fracture toughness and ductility associated with damage of low alloy steels in the beltline region. In the lower head region of the reactor vessel, the thermal neutron fluence (E < 0.5 eV) is predicted to be below the threshold of concern for weldability based upon the findings in BWRVIP-97-A, which shows that vessel internals components below the core plate are all considered within the generic weldability boundary. This weld overlay will be installed external to the reactor vessel below the core plate elevation.,

Therefore, there is not a weldability concern for the repair.

(g) A new weld overlay shall not be installed over the top No Additional layers of Alloy The existing leakage barrier weld overlay of an existing weld overlay that has been in service. 52M filler material, will be volumetrically examined. The estimated at 4-7 layers, volumetric examination will also confirm will be applied to the the laminar indication accepted per Relief leakage barrier weld Request I5R-14 (ML23156A683) remains

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Included in Exceptions to N-740-2 ASME Code Case N-740-2 Requirement Proposed Justification (highlighted in bold)

Alternative acceptable per Non-Mandatory overlay using the Appendix Q. Upon volumetric and surface machine GTAW process examinations of the existing leakage to achieve the designed barrier weld overlay, the FSWOL will be FSWOL thickness.

completed by installing additional weld layers as necessary.

The intent of this requirement in Code Case N-740-2 is to prevent a leaking overlay from being repaired with a second weld overlay. Volumetric and surface examinations will confirm the integrity of the leakage barrier weld overlay prior to installing the remaining weld layers needed to complete the FSWOL.

Additionally, removal of the existing leakage barrier weld overlay may result in a reactor coolant leak since ultrasonic examination showed the initial flaw had relieved to the interface of the original Alloy 82/182 weld and the Alloy 82 bridge beads applied during installation of the leakage barrier weld overlay.

2 CRACK GROWTH AND DESIGN (a) Crack Growth Calculation of Flaws in the Original Weld Yes These requirements are equivalent, or N/A or Base Metal. The size of the flaw detected in the base metal more stringent, than those specified in shall be used to define the life of each overlay. The inspection Nonmandatory Appendix Q. ASME Code, interval shall not be longer than the shorter of the life of the Section XI, Non-Mandatory Appendix Q overlay or the period specified in 5.1.4(c). Crack growth due to has been accepted for use by the NRC.

both stress corrosion and fatigue, shall be evaluated. Flaw These requirements will ensure that the characterization and evaluation shall be based on the growth of the flaw will be accounted for in examination result or postulated flaw, as described below. If the the design of the overlay.

flaw is at or near the boundary of two different materials, evaluation of flaw growth in both materials is required.

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Alternative (1) For repair overlays, the initial flaw size for crack No This requirement is not applicable and is N/A growth in the original weld or base metal shall be based on the not used in the alternative because a as-found flaw or postulated flaw, if no pre-overlay examination repair overlay is not being proposed.

is performed.

(2) For postulated flaws, the axial flaw length shall be Yes This requirement is met as a 100% N/A 1.5 inches (i.e., 38 millimeters) or the combined width of the through-wall circumferential flaw is weld plus buttering plus any adjacent stress corrosion cracking assumed in the sizing of the FSWOL.

(SCC) susceptible material, whichever is greater. The circumferential flaw length shall be assumed to be 360 degrees. The depths associated with these lengths are specified in (3) and (4).

(3) If an Appendix VIII, Supplement 10, or Supplement No This requirement is not applicable N/A 2, as applicable, ultrasonic examination is performed prior to because ultrasonic examinations have application of the overlay, and no inside-surface-connected determined the identified flaw to be ID planar flaws are discovered, initial flaws originated from the connected. The requirement does not inside surface of the weldment equal to 10 percent of the apply to the proposed alternative.

original wall thickness shall be assumed in both the axial and circumferential directions, and the overlay shall be considered mitigative.

(4) If an Appendix VIII, Supplement 10, or Supplement No The requirement does not apply to the N/A 2, as applicable, ultrasonic examination is not performed prior proposed alternative because ultrasonic to application of the overlay, initial inside-surface-connected examinations have been performed planar flaws equal to at least 75 percent through the original following completion of the leakage barrier wall thickness shall be assumed, in both the axial and weld overlay and showed that the initial circumferential directions, and the overlay shall be considered flaw had relieved to the interface of the a repair. For cast austenitic stainless steel (CASS) items, a original Alloy 82/182 weld and the Alloy 82 100 percent through-wall flaw shall be assumed unless the bridge beads applied during installation of subsequent in-service inspection schedule is modified. the leakage barrier weld overlay.

Additionally, volumetric examinations of the existing leakage barrier weld overlay will be performed as part of the proposed alternative to ensure the flaw is characterized.

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Alternative (5) There may be circumstances in which an overlay No The requirement does not apply to the N/A examination is performed using an ultrasonic examination proposed alternative because ultrasonic procedure qualified in accordance with Appendix VIII, examinations have been performed prior Supplement 11 for depths greater than the outer 25 percent of to application of the overlay.

the original wall thickness. 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.

(6) In determining the life of each overlay, any inside- Yes Ultrasonic examination of the leakage N/A surface-connected planar flaw found by the overlay preservice barrier weld overlay in N1R27 showed that inspection that exceeds the depth of (3), (4), or (5) above shall the initial flaw has relieved to the interface be used as part of the initial flaw depth. The initial flaw depth of the original Alloy 82/182 weld and the assumed is the detected flaw depth plus the postulated worst- Alloy 82 bridge beads applied during case flaw depth in the region of the pipe wall thickness that was installation of the leakage barrier weld not examined using an ultrasonic examination procedure overlay. Volumetric examination of the meeting Appendix VIII for that region. An overlay meeting this existing leakage barrier weld overlay will condition shall be considered a repair, rather than mitigation. be performed prior to application of additional Alloy 52M weld material to confirm the flaw dimensions. Following the completion of the FSWOL, preservice inspections will be performed on the entire weld overlay volume including the initial flaw found in the base material during N1R27. This flaw dimension will be used to determine the life of the FSWOL.

(b) Structural Design and Sizing of the Overlay. The Yes This requirement is met, as indicated in N/A design of the weld overlay shall satisfy the following, using the (1), (2), (3), and (4) below.

assumptions and flaw characterization requirements. The following design analysis shall be completed in accordance with IWA-4311:

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Alternative (1) The axial length and end slope of the weld overlay Yes These requirements are essentially the N/A shall cover the weld and heat-affected zones on each side of same as ASME Code,Section XI, Non-the weld, as well as any SCC-susceptible base material Mandatory Appendix Q, Article Q-adjacent to the weld and provide for load redistribution from the 3000(b)(1), which has been accepted for item into the weld overlay and back into the item without use by the NRC.

violating applicable stress limits of NB-3200. Any laminar flaws in the weld overlay shall be evaluated in the analysis to ensure that load redistribution complies with the above. These requirements 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).

(2) Unless specifically analyzed in accordance with (1), Yes The alternative shall comply with this N/A the end transition slope of the overlay shall not exceed 30 deg. requirement. The end transition slope of FSWOL shall not exceed 45 deg., and the FSWOL will be analyzed for this transition slope.

(3) The assumed flaw in the underlying base material Yes The limiting case of (3)(-a) shall be used N/A or weld shall be based on the limiting case of (-a) and (-b) that to determine the required thickness of the results in the larger required overlay thickness. FSWOL.

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

(-b) 100% through-wall flaw with length of 1.5 in.

(38 mm) or the combined width of the weld plus buttering plus any SCC-susceptible material, whichever is greater, in the axial direction

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Alternative (4) The overlay design thickness shall be verified, Yes These requirements are essentially the N/A using only the weld overlay thickness conforming to the deposit same as ASME Code,Section XI, Non-analysis requirements. The combined wall thickness at the Mandatory Appendix Q, Article weld overlay, any postulated worst-case planar flaws under the Q-3000(b)(3), which has been accepted laminar flaws in the weld overlay, and the effects of any for use by the NRC.

discontinuity within a distance of 2.5 (Rt), from the toes of the weld overlay, including the flaw size assumptions, shall 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 Yes These requirements are more stringent N/A result of weld shrinkage from the entire overlay, on other items than ASME Code,Section XI, Non-in the piping system (e.g., support loads and clearances, Mandatory Appendix Q, Article nozzle loads, and changes in system flexibility and weight due Q-3000(b)(4), which has been accepted to the weld overlay) shall be evaluated. Existing flaws for use by the NRC.

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

3 EXAMINATION In lieu of all other examination requirements, the Yes The requirements for qualification of Ultrasonic examination examination requirements of this Case shall be met for ultrasonic examination personnel in personnel shall be the life of the overlay. Nondestructive examination IWA-2300 of the 2013 Edition of ASME qualified in accordance methods shall be in accordance with IWA-2200, Code,Section XI have been approved by with IWA-2300.

except as specified herein. Nondestructive the NRC in 10 CFR 50.55a.

Ultrasonic examination examination personnel shall be qualified in accordance ASME Code,Section XI, Code Case procedures will be with IWA-2300. Ultrasonic examination procedures N-653-2 is included in Table 1 of qualified in accordance and personnel shall be qualified in accordance Regulatory Guide 1.147, Revision 20 and with the requirements of with Appendix VIII, Supplement 11. The is listed as available for use in the NMP1 ASME Code Case examination shall be performed to the maximum extent ISI Program. N-653-2, Qualification practicable, for axial and circumferential flaws. If 100% Requirements for Full coverage of the required volume for axial flaws cannot Structural Overlaid be achieved, but essentially 100% coverage for Wrought Austenitic circumferential flaws (100% of the susceptible Piping Welds.

volume) can be achieved, the examination for axial

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Alternative flaws shall be per- formed to achieve the maximum There are no cast coverage practicable, with limitations noted in the stainless steel examination report. The ex- amination coverage components that will be requirements shall be considered to be met. For cast overlayed by the stainless steel components for which no FSWOL.

supplement is available in Appendix VIII, the weld volume shall be examined using Appendix VIII procedures to the maximum extent practicable.

(a) Acceptance Examination Yes The surface finish requirements of Code Ultrasonic examination Case N-740-2 are the same as ASME procedures will be (1) The weld overlay shall have a surface finish Code,Section XI, Non-Mandatory qualified in accordance of 250 in. (6.3 m) RMS or better and contour that Appendix Q, Article Q-4100 which has with the requirements of permits ultrasonic examination in accordance with been accepted for use by the NRC. Code Case N-653-2, procedures qualified in accordance with Appendix Qualification VIII. The weld overlay shall be inspected to verify Code Case N-653-2 is included in Table 1 Requirements for Full acceptable configuration. of Regulatory Guide 1.147, Revision 20 Structural Overlaid and is listed as available for use in the Wrought Austenitic NMP1 ISI Program.

Piping Welds.

(2) The weld overlay and the adjacent base Yes The surface examination requirements Ambient temperature material for at least 1/2 in. (13 mm) from each side of the and acceptance criteria for the weld temper bead welding is overlay shall be examined using the liquid penetrant overlay and adjacent base material are not required for method. The weld overlay shall satisfy the surface equivalent to ASME Code,Section XI, completion of the examination acceptance criteria for welds of the Non-Mandatory Appendix Q, Article FSWOL in N1R28, so the Construction Code or NB-5300. The adjacent base Q-4100 which has been accepted for use 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold is not material shall satisfy the surface examination by the NRC. required.

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 shall be conducted no sooner than 48 hr following completion of the three tempering layers over the ferritic steel.

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Alternative (3) The examination volume A-B-C-D in Figure Yes The examination requirements in Code N/A 1(a) shall be ultrasonically examined to assure Case N-740-2, Figure 1(a) are identical to adequate fusion (i.e., adequate bond) with the base those specified in Section XI, material and to detect welding flaws, such as interbead Nonmandatory Appendix Q, Figure lack of fusion, inclusions, or cracks. The interface C-D Q-4100-1, which has been accepted for shown between the overlay and weld includes the use by the NRC.

bond and heat-affected zone from the overlay. If ambient temperature temper bead welding is performed, the ultrasonic examination shall be conducted no sooner than 48 hr following completion of the three tempering layers over the ferritic steel.

Planar flaws detected in the weld overlay acceptance examination shall meet the preservice examination standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness, t 1 , or t2 defined in Figure 1(b), shall be used as the nominal wall thickness in IWB-3514, provided the base material be- neath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to SCC. For susceptible material, t 1 shall be used. If a flaw in the overlay crosses the boundary be- tween the two regions, the more conservative of the two dimensions (t1 or t2 ) shall be used. Laminar flaws in the weld overlay shall meet the following requirements:

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Alternative

(-a) The acceptance standards of IWB-3514 shall Yes The proposed acceptance standards in Additional limitations of be met, with the additional limitation that the total laminar IWB-3514 have been accepted by the N-740-2 are not being flaw area shall not exceed 10% of the weld surface area NRC in Section XI, Non-Mandatory applied. Non-Mandatory and that no linear dimension of the laminar flaw area Appendix Q for use. Appendix Q acceptance shall exceed the greater of 3 in. (76 mm) or 10% of the criteria will be used.

During the installation of the leakage pipe circumference. barrier weld overlay; one laminar flaw was identified and accepted per Non-Mandatory Appendix Q in Relief Request I5R-14 (ML23156A683).

Prior to installation of the additional FSWOL weld layers, volumetric examination will confirm the laminar flaws identified in the leakage barrier weld overlay remain acceptable per Non-Mandatory Appendix Q.

(-b) For examination volume A-B-C-D in Figure Yes Code Case N-740-2, Figure 1(a) is N/A 1(a), the reduction in coverage due to laminar flaws shall be equivalent to ASME Code,Section XI, less than 10%. The uninspectable volume is the volume in Non-Mandatory Appendix Q, Figure the weld overlay underneath the laminar flaws for which Q-4100-1, which has been accepted by coverage cannot be achieved with the angle beam the NRC for defining the acceptance examination method. examination volume for weld overlay repairs.

(-c) Any uninspectable volume in the weld overlay Yes The acceptance standards in Code Case N/A shall be assumed to contain the largest radial planar flaw that N-740-2 for the weld overlay are could exist within that volume. This assumed flaw shall meet equivalent to, or more stringent than, the the preservice examination acceptance standards of rules of ASME Code,Section XI, Non-IWB-3514, with nominal wall thickness as defined above the Mandatory Appendix Q, Article Q-4100 planar flaws. Alternatively, the assumed flaw shall be which has been accepted for use by the evaluated and meet the requirements of IWB-3640, NRC.

IWC-3640, and IWD-3640, as applicable. Both axial and circumferential planar flaws shall be assumed.

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Alternative (4) After completion of all welding activities, VT-3 Yes A VT-3 visual examination of all affected N/A visual examination shall be performed on all affected restraints, supports, or snubbers (if restraints, supports, and snubbers, to verify that design applicable) will be performed to ensure tolerances are met. that they have been returned to the design configuration following application of the weld overlay.

N-740-2 Figure 1, Acceptance Examination Volume and Yes Figure 1(a) is identical to that specified in N/A Thickness Definitions Code Case N-740-2, Figure 1(a) and ASME Code,Section XI, Non-Mandatory Appendix Q, Figure Q-4100-1, which has been accepted by the NRC.

The examination volume required by Figure 1(b) is specified to ensure that the portion of the FSWOL that covers the DM weld is capable of providing structural integrity in lieu of the underlying DM weld.

Flaws in this region of the FSWOL are evaluated using the thickness t1 when applying the preservice acceptance standards of IWB-3514.

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Alternative (b) Preservice Inspection Yes The examination volume specified in Code The rules for weld Case N-740-2, Figure 2 is identical to that overlays on cast (1) The examination volume in Figure 2 shall be in Section XI, Nonmandatory Appendix Q, austenitic stainless steel ultrasonically examined. The angle beam shall be directed Figure Q-4300-1, which has been base materials is not perpendicular and parallel to the piping axis, with scanning accepted by the NRC. applicable based on the performed in four directions, to locate and size any planar configuration. There are flaw that have propagated into the outer 25% of the base no cast stainless steel metal thickness or into the weld overlay. For weld overlays materials that will be on cast austenitic stainless steel base materials, if a overlayed by the 100% through-wall flaw is used for crack growth, only FSWOL.

planar flaws that have propagated into the weld overlay, or are in the overlay, are required to be located and sized.

(2) The preservice examination acceptance standards Yes The preservice examination acceptance N/A of IWB-3514 shall be met for the weld overlay. In applying the standards of Code Case N-740-2 are acceptance standards to planar indications, the thickness, t 1 equivalent, or more stringent than, the or t2, defined in Figure 1(b), shall be used as the nominal wall requirements of ASME Code,Section XI, thickness in IWB-3514, provided the base material beneath Non-Mandatory Appendix Q, Article the flaw (i.e., safe end, nozzle, or piping material) is not Q-4200, which has been accepted by the susceptible to SCC. For susceptible material, t1 shall be NRC.

used. Planar flaws in the outer 25% of the base metal thickness shall meet the design analysis requirements of 2(b).

(3) The flaw evaluation requirements of IWB-3640, Yes Planar flaws identified during preservice N/A IWC-3640, or IWD-3640 shall not be applied to planar examination of the weld overlay shall not flaws, identified during preservice examination, that exceed be accepted by evaluation. Any flaws the preservice examination acceptance standards of IWB- identified during preservice inspection of 3514. the weld overlay are required to be repaired or reduced to an acceptable size.

This will confirm that there are no unacceptable planar flaws in the weld overlay volume.

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Alternative (c) Inservice Inspection Yes If the life of the overlay is less than the N/A length of the inspection interval, this (1) The weld overlay examination shall be added to requirement will ensure that the overlay is the inspection plan. The weld overlay inspection interval examined prior to the end of the life of the shall not be greater than the life of the overlay as overlay. This requirement is more determined in 2(a) above. All weld overlays shall be stringent than that specified in Section XI, examined prior to the end of their design life. Nonmandatory Appendix Q.

(2) The weld overlay examination volume in Figure 2 Yes This requirement is identical to Section XI, The FSWOL is not shall be ultrasonically examined during the first or second Nonmandatory Appendix Q, Q-4300(a), considered a mitigative refueling outage following application. Alternatively, for which has been approved for use by the weld overlay mitigative weld overlays, in which pre-overlay NRC. These examinations will confirm examinations are performed in accordance with 2(a)(3), whether there has been any growth of the post- overlay examinations are performed in flaw in the overlaid weld.

accordance with (a) and (b), and no inside-surface- The FSWOL shall be ultrasonically connected planar flaws are discovered, the overlay may examined during the first or second be placed immediately into the population to be refueling outage following application.

examined in accordance with (5).

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

Figure 2 of the alternative is identical to that in Section XI, Nonmandatory Appendix Q, Figure Q-4300-1 and Code Case N-740-2, Figure 2. ASME Code,Section XI, Non-Mandatory Appendix Q, Figure Q-4100-1, for FSWOL examination at time of installation, has been accepted by the NRC.

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Alternative (4) The weld overlay shall meet the inservice Yes Figure 2 is identical to that in ASME Code, N/A examination acceptance standards of IWB-3514. In Code Case N-740-2, Figure 2 and applying the acceptance standards to planar indications, the Nonmandatory Appendix Q, Figure Q-thickness, t1 or t2 , defined in Figure 1, sketch (b), shall be 4300-1. ASME Code,Section XI, Non-used as the nominal wall thickness in IWB-3514, provided Mandatory Appendix Q, Figure Q-4100-1, the base material beneath the flaw (i.e., safe end, nozzle, for FSWOL examination at time of or piping material) is not susceptible to SCC. For installation, has been accepted by the susceptible material, t1 shall be used. If the acceptance NRC.

standards of IWB-3514 cannot be met, the weld overlay shall meet the acceptance standards of IWB-3600, IWC-3600, or IWD-3600, as applicable. If a planar flaw is detected in the outer 25% of the base material thickness shall meet the design analysis requirements of 2. Any indication characterized as stress corrosion cracking in the weld overlay material is unacceptable.

(5) Weld overlay examination volumes in Figure 2 that Yes This requirement is identical to that in N/A show no indication of planar flaw growth or new planar Code Case N-740-2 and Nonmandatory flaws shall be placed into a population to be examined on a Appendix Q. ASME Code,Section XI, sample basis, except as required by (1). Twenty-five Non-Mandatory Appendix Q, has been percent of this population shall be examined once during accepted by the NRC.

each inspection interval.

(6) If inservice examinations reveal planar flaw Yes This requirement is identical to that in N/A growth, or new planar flaws, meeting the acceptance Code Case N-740-2 and is essentially the standards of IWB-3514, IWB-3600, IWC-3600, or IWB- same as that required by Nonmandatory 3600, the weld overlay examination volume shall be Appendix Q. ASME Code,Section XI, reexamined during the first or second refueling outage Non-Mandatory Appendix Q, has been following discovery of the growth or new flaws. accepted by the NRC.

(7) For weld overlay examination volumes with un- Yes The alternative shall comply with this N/A acceptable indications in accordance with (4), the weld requirement.

overlay, and original defective weld shall be removed. A repair/replacement activity shall be performed in accordance with IWA-4000.

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Alternative (8) If preservice and inservice examinations in No This requirement does not apply to the N/A accordance with ASME Section XI, Appendix VIII, proposed alternative because there are no Supplement 11 cannot be performed for the entire weld cast austenitic stainless steel materials overlay examination volume in Figure 2 because of cast being overlayed.

austenitic stainless steel items, and a 100% initial flaw assumption is not used in the crack growth evaluation of 2(a), a 75% through- wall depth may be assumed in the crack growth calculation, provided that the required examination volume is examined at a higher frequency than the requirements in (c). The subject weld shall be ultrasonically examined during the first or second refueling outage following the weld overlay installation. If ultrasonic examination is performed prior to weld overlay installation and after installation without detecting any planar flaws in the original weld or the weld overlay, then the ultrasonic examination during the first or second refueling outage is not required. After the first inservice examination, the required examination volume shall be ultrasonically examined every 10 years from the date of the installation until such time when ultrasonic examination is qualified to examine the cast austenitic stainless-steel portion of the required inspection volume in accordance with the performance demonstration requirements of ASME Code,Section XI, Appendix VIII. The inspection of the overlaid weld shall not be credited to satisfy the requirement of the 25% inspection sample every ten years of overlaid welds without cast stainless steel materials.

After the required examination volume is examined by qualified ultrasonic examination for the cast austenitic stainless-steel material and no planar flaws are detected, the weld may be placed in the 25% inspection sample population in accordance with (5).

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Alternative N-740-2 Figure 2, Preservice and Inservice Examination Yes This figure is identical to that in ASME N/A Volume Code,Section XI, Non-Mandatory Appendix Q, Figure Q-4300-1.

Nonmandatory Appendix Q. ASME Code,Section XI, Non-Mandatory Appendix Q, has been accepted by the NRC.

(d) Additional Examinations. If inservice examinations Yes This requirement is essentially the same N/A reveal a defect, in accordance with (c)(4) above, planar flaw as that in Section XI, Nonmandatory growth into the weld overlay design thickness, or axial flaw Appendix Q, Q-4310. Nonmandatory growth beyond the specified examination volume, additional Appendix Q. ASME Code,Section XI, weld overlay examination volumes, equal to the number Non-Mandatory Appendix Q, has been scheduled for the current inspection period, shall be accepted by the NRC.

examined prior to return to service. If additional defects are found in the second sample, 50% of the total population of weld overlay examination volumes shall be examined prior to return to service. If additional defects are found, the entire remaining population of weld overlay examination volumes shall be examined prior to return to service.

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Alternative 4 PRESSURE TESTING Yes IWA-5214 requires a preservice system N/A pressure test following repair/replacement A system leakage test shall be performed in accordance activities in accordance with IWA-4540.

with IWA-5000. IWA-4540(b)(3) exempts welding or brazing that does not penetrate through the pressure boundary from a pressure test and VT-2 examination. The FWSOL does not penetrate through the full thickness of the pressure boundary and is therefore exempt from the pressure testing requirements of IWA-4540.

However, the FSWOL is within the boundary of IWB-5222(a) and will be subject to pressurization and VT-2 examination as part of the Class 1 system leakage test prior to return to service.

5 DOCUMENTATION Yes Documentation of the use of this ASME N/A Code Case in the post outage summary Use of this Case shall be documented on Form NIS-2. report is an administrative requirement.

MANDATORY APPENDIX I, AMBIENT-TEMPERATURE No Ambient temperature temper bead welding N/A TEMPER BEAD WELDING is not required for completion of the FSWOL in N1R28.

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