ML090830726

Fourth Ten Year Inservice Inspection Interval, Request for Relief No. 09-ON-003

ML090830726
Person / Time
Site:	Oconee
Issue date:	03/20/2009
From:	Baxter D Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
09-ON-003
Download: ML090830726 (37)

Text

Duke DAVE BAXTER Vice President Oconee Nuclear Station Duke Energy

• March 20, 2009 ON01 VP / 7800 Rochester Highway Seneca, SC 29672 864-873-4460 U.S. Nuclear Regulatory Commission 864-873-4208 fax Washington, DC 20555-0001 dabaxter@dukeenergy.com Attention: Document Control Desk

Subject:

Duke Energy Carolinas, LLC Oconee Nuclear Station, Unit 1, 2, 3 Docket No: 50-269, 50-270, 50-287 Fourth Ten Year Inservice Inspection Interval Request for Relief No. 09-ON-003 Pursuant to 10 CFR 50.55a(a)(3)(i), Duke hereby requests NRC approval to use alternatives to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section Xl, Rules for Inservice Inspection of Nuclear Power Plant Components, for the Oconee Nuclear Station, Units 1, 2, and 3.

This proposed alternative approach is to support application of full structural weld overlays (FSWOL) associated with the mitigation of reactor coolant system (RCS) letdown nozzles and lines against Primary Water Stress Corrosion Cracking (PWSCC).

This alternative will provide an acceptable level of quality and safety.

In addition, in this relief request Duke is also asking for NRC pre-approval of the contingent full structural weld overlay for the reactor vessel core flood (CF) and reactor coolant pump (RCP) inlet and outlet (1/O) nozzles Alloy 82/182 butt welds. These nozzles will be volumetrically inspected during the next scheduled refueling outage for each unit. Should indications be identified during the inspection and subsequent qualification is not possible and local repair options are not applicable, full structural weld overlays will be applied to mitigate the potential for PWSCC.

This relief request is needed to support the Oconee Unit 1 Fall 2009 refueling outage (1 EOC25) scheduled to start October 25, 2009. This relief is also intended to apply to Oconee Units 2 and 3, which are scheduled for outages in 2010.

This submittal contains three commitments to provide additional data related to the weld overlays. The first commitment is that Duke will submit, prior to entry into Mode 6 from the Oconee Unit 1 outage in the fall of 2009, a summary of the results of the stress analyses demonstrating that the letdown nozzle preemptive full structural weld overlay will not hinder the components from performing their design function. The second commitment is that Duke will submit, within 14 days from completion of Ultrasonic Test (UT) examinations on all implemented full structural weld overlays on each unit, a report that summarizes the results of the UT examination on each overlay. The third commitment is that Duke will submit within 60 days of startup, the fatigue crack growth 404y7 www. duke-energy, corn M~ t1

U. S. Nuclear Regulatory Commission March 20, 2009 Page 2 analysis associated with the FWSOL for the CF or RCP I/O nozzles, only if a FSWOL is installed on any of these nozzles.

If there are any questions or further information is needed you may contact Corey Gray at (864) 873-6325, Sincerely, 4* Dave Baxter, Site Vice President Enclosure

U. S. Nuclear Regulatory Commission March 20, 2009 Page 3 xc w/att:

Luis Reyes Region II Administrator U.S. Nuclear Regulatory Commission Atlanta Federal Center 61 Forsyth St., SWW, Suite 23T85 Atlanta, GA 30303 John Stang Project Manager U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D.C. 20555 xc(w/o attch):

Andy Hutto Senior NRC Resident Inspector Oconee Nuclear Station Susan Jenkins Section Manager Division of Waste Management Bureau of Land and Waste Management SC Dept. of Health & Environmental Control 2600 Bull St.

Columbia, SC 29201

Request No. 09-ON-003 Enclosure I Proposed Alternative In Accordance with 10 CFR 50.55a(a) (3) (i)

- Alternative Provides Acceptable Level of Quality and Safety -

Duke Energy Corporation Oconee Units 1, 2and 3 Request for Alternative 09-ON-003 CONTENTS 1.0 ASME CODE COMPONENTS AFFECTED...............................................................

2.0 APPLICABLE CODE EDITION AND ADDENDA...............................................

4 3.0 APPLICABLE CODE REQUIREMENTS...................................

4 4.0 REASON FOR THE REQUEST..............................................................................

4 5.0 PROPOSED ALTERNATIVES AND BASIS FOR USE........................................

5 6.0 WELD OVERLAY DESIGN AND VERIFICATION.............................................

16 7.0 DURATION OF THE PROPOSED ALTERNATIVES..........................................

17 8.0 P R E C E D E N T S.......................................................................................................

.. 17 9.0 R E F E R E N C E S.............................................................................................................

19 10.0 C O N C L U SIO N.......................................................................................................

20 A ttachm ent I..................................

........................................................24 List of Figures Figure 1: Letdown Line Nozzle Weld Overlay (Schematic).........................

21 Figure 2: Core Flood Nozzle W eld Overlay (Schem atic).............................................................

21 Figure 3: Unit I RCP Suction Weld Overlay (Schematic)....................................................

22 Figure 4: Unit 2 and 3 RCP Suction Weld Overlay (Schematic).............................................

22 Figure 5: RCP Discharge Weld Overlay (Schematic)...............................................................

23 List of Tables Table 5.1 Dissimilar Metal Weld Overlay Experience.................................

13 Table Al Modifications To Code Case N-504-3 and Corresponding Nonmandatory A ppendix Q R equirem ents.................................................................................................

25 Table A2... Alternatives to Appendix VIII, Supplement 11......................................................

27 Table A 3... M odifications to Code Case N -638-1........................................................................

33, 0900082.402. Rev. 0 Page 1 of 34

Request No. 09-ON-003 Enclosure I 1.0 ASME CODE COMPONENTS AFFECTED System:

Reactor Coolant System Component Number:

ii ii Oconee 1<*ci 1ption RCS Let-Let-Down Line Nozzle 12.5" ID

)own line to Safe-End (CS Let-Let-Down Line Safe-

ý2.5" ID Down line End to Piping

{,

RP AIIuction (transition piece 28" ID to pipe)

Discharge (safe-end to 28" ID pipe elbow)

RCP IA2 Suction (transition piece 28" ID

.to pipe)

Discharge (safe-end to 128" ID pipe elbow)

RCP IBI Suction (transition. piece 228" ID to pipe)

Discharge (safe-end to 28" ID pipe elbow)

RCPI B12 Suction (transition piece 28" ID to pipe)

Discharge (safe-end to 128" ID

~pipe elbow)

.P...! ° w........,.........................

i...........

Core Flood Core Flood Nozzle to 14" ID Safe-End (W Axis)

Core Flood Nozzle to ID

.......Safe-En (Y.....

A xis).....-

zel T 1 -PIB I-ASTM A-105 Grade 2 nozzle/Alloy 82-182 weld/Inconel B-166 safe-end I.

1-51A-7-7E n co neI B -16 6 s afe -e nd/AllIoy 8 2-18 2 welId/A SM E SA-40) Grade WP316 elbow 1-PIAI-7 A-182 TP F316 transition piece/Alloy 82-182 weld/A106 GR C pipe I-PDA2-2 A-376 TP 316 safe-end/Alloy 82-182 weld/SA-516 GR 70 pipe elbow i-PIA2-7 A-I 82 TP F3 16 transition piece/Al oy 82-182 weld/A 106 GR C pipe i-PDA2-2 A-376 TP 316 safe-end/Alloy 82-182 weld/SA-516 CGR 70 pipe elbow I-PIB1-7 i A-182 TP F3 16 transition piece/Alloy 82-182

.weld/Ad 06 CR C pipe 1-PDB1-2 A-376 TP 316 safe-end/Alloy 82-182 weld/SA-516 GR 70 pipe elbow I-PIB2-7

ýA-182 TP F3 16 transition piece/Alloy 82-182

.weld/.A106 CR C ipie___

I1-PDB2-2 A-376 TP 316 safe-end/Alloy 82-182 weld/SA-516 CGR 70 pipe elbow 1-RPV-WR53 ASTM A508-64 Class 2 nozzle/Alloy 82-182

.weld/ASTM A 336-65 Class F8M safe-end ii*:*i~iT:'*-*+?,-X*"X....

@f~s*~zze3-iT-*:i*

I-RPV-WR53A AST M

A508-64 Class 2 nozzle/Alloy 82-182

.weld/ASTM A 336-65 Class F8M safe-end RUS Let-Let-Down Line Nozzle 2.5" ID Down line to Safe-End RCS Let-i~et-Down Line-Safe-I2.

ID i2-51A-35-15A Down line End to Piping RCP 2A I Suction (safe-end to pipe).

Discharge (safe-end to pipe elbow)

RCP 2A2 Suction (safe-end to pipe)

Discharge (safe-end to pipe elbow) 28" ID 28" ID 28" ID 28" ID 2-PIA 1-7 2-PDA1-2 i2-PIA2-7 2-PDA2-2

.AS IM A-lU_ Urade 2 nozzle/Alloy Z2-1Z2

,weld/Inconel B-166 safe-end Inconel 13-166 safe-end/Alloy 82-182 weld/ASME SA-403 Grade WP316 elbow SA-376 TP316 safe-end/Alloy 82-182 weld/A 106 CGR C pipe A-376 TP 316 safe-end/Alloy 82-182 weld/SA-516 GR 70 pipe elbow' SA-376 TP316 safe-end/Alloy 82-182 weld/A106 GR C pipe A-376 TP 316 safe-end/Alloy 82-182 weld/SA-516 GR 70 pipe elbow Page 2 of 34

Request No. 09-ON-003 Enclosure I Ocon ee

~Uniti Descrilption

,Size&

ýVIed Number RCP 2B I Suction (safe-end to ipipe)

Discharge (safe-end to

'pipe elbow)

RCP 2B2 Suction (safe-end to pipe)..

Discharge (safe-end to pipe elbow)

Core Flood iCore-Flood Nozzle to Safe-End (W Axis)

Core Flood Nozzle to Safe-End (Y Axis).

i28" ID 28" ID

28" ID 28" ID 14" ID 14" ID 12-PIBI-7 2-PDB 1-2 A-376 TP316 safe-end/Alloy 82-182 weld/SA-516 CGR 70 pipe elbow 2-PIB2-7 SA-376 TP316 safe-end/Alloy 82-182 weld/A 106 GR C pipe 2-PDB2-2 A-376 TP316 safe-end/Alloy 82-182 weld/SA-516 G

70 pipe elbow

ý2-RPV-WR53 ASTM A508-64 Class 2 nozzle/Alloy 82-182 weld/ASTM A 336-65 Class F8M safe-end i.......

w.!d A T

!.s a

.ee

ý2-RPV-WR53A ASTM A508-64 Class 2 nozzle/Alloy 82-182 weld/ASTM A 336-65 Class F8M safe-end SA-376 TP316 safe-end/Alloy 82-182 weld/A106

'GR C pipe 4 A-105 Grade 2 nozzle/Alloy 82-182 Down line Ito Safe-End RCS Let-Let-Down Line Safe-Down l

.ine Endto Piping.

RCP 3A I Suction (safe-end to pipe)

Discharge (safe-end to Rpipe elbow)

Rc

-3A2 Suction (safe-end to pipe)

Discharge (safe-end to

.. pipe elbow)

RCP 3 B I Suction (safe-end to pipe)

Discharg~e (safe-end to pipe elbow)

,RCP 3B32 ISuction (safe-end to

~pipe)

.!. e. )

Discharge (safe-end to pipe elbow)

Core Flood Core Flood Nozzle to Safe-End (W Axis)

Core Flood Nozzle to Safe-End (Y Axis) 2.5" ID 28" ID 28" ID 28" ID 28.."

ID 28" ID 28" ID 28" ID 28" ID 14" ID 14" ID 3-RC-265-79 13-PIAI-7

'3-PDA 1-2 3-PIA2-7 13-PDA2-2 3-PIB1-7 i3-PDBI-2 3-PIB2-7 3-PDB2-2

ý3-RPV-WR53

.3-RPV-WR53A weld/l nconel B-166 safe-end Inconel B-166 safe-end/Alloy 82-182 weld/ASM E SA-403 Grade WP316 elbow SA-376 TP316 safe-end/Alloy 82-182 weld/A 106

.GR C pipe A-376 TP 316 safe-end/Alloy 82-182 weld/SA-516 jGR 70 pipe elbow SA-376 TP316 safe-end/Alloy 82-182 weld/A 106

.GR C pipe A-376 TP316 safe-end/Alloy 82-182 weld/SA-516 GR 70 pipe elbow SA-3 76 TP3 16 safe-end/Al 1oy 82-182 weld/A 106 GR C pipe A-376 TP316 safe-end/Alloy 82-182 weld/SA-516*

.GR70.pipe elbow 1

,SA-3 76TP316 safe-end/Alloy 82-182 weld/A 106 CGR C pipe A-376 TP316 safe-end/Alloy 82-182 weld/SA-516 GR 70 pipe elbow ASTM A508-64 Class 2 nozzle/Alloy 82-182 weld/ASTM A 336-65 Class F8M safe-end ASTM A508-64 Class 2 nozzle/Alloy 82-182 weld/ASTM A 3 36-65 Class F8M safe-end Code Class:

Class 1 Examination Category:

Code Item Number:

B-J (Letdown Line); B-F (Core Flood); B-J-1 (RCP suction/discharge)

B9.21 (Letdown Line); B5.10 (Core Flood); B9.1 I(RCP suction/discharge)

Page 3 of 34

Request No. 09-ON-003 Enclosure I 2.0 APPLICABLE CODE EDITION AND ADDENDA Inservice Inspection:

ASME Boiler and Pressure Vessel Code, Section Xl, 1998 Edition through 2000 Addenda Design and Fabrication:

USAS B31.7 1968, with errata dated June 1968. The Oconee RCS was reanalyzed to ASME Section II1, Subsection NB, 1983 Edition, no addenda.

Duke Energy Welding Program:

ASME Boiler and Pressure Vessel Code,Section III, 1989 Edition no Addenda.

3.0 APPLICABLE CODE REQUIREMENTS ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda, Article IWA-4000, "Repair/Replacement Activities" [1]

ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda, Appendix VIII, Supplement 11, "Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds" [2]

Code Case N-504-3 with requirements of ASME Code,Section XI, Nonmandatory Appendix Q, "Weld Overlay Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping Weldments"

[3, 4]

Code Case N-638-1, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique" [5]

4.0 REASON FOR THE REQUEST Dissimilar Metal Welds (DMW) made with nickel alloys 82 and 182 have been shown to be susceptible to Primary Water Stress Corrosion Cracking (PWSCC) degradation in components that are subjected to higher operating temperatures. Structural weld overlays have been used for several years on piping of both Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs) to arrest the growth of existing flaws while establishing a new structural pressure boundary. No evidence of PWSCC has been found in the welds of the Oconee Reactor Coolant System (RCS); however, PWSCC is difficult to detect in DMW except when the inspection is performed in accordance with the stringent requirements of ASME Section XI, Appendix VIII. Some of the DMW included in this request for relief have been evaluated and found not to meet the surface or geometric requirements of Appendix VIII. The feasibility of modifying the geometry to an acceptable configuration has not been established. Rather than risk multiple cycles of inspection and modification, Oconee Nuclear Station (ONS) is proposing to take a proactive approach to apply a Full Structural Weld Page 4 of 34

Request No. 09-ON-003 Enclosure I Overlay (FSWOL) only to the DMW of the Letdown line nozzle, safe end and elbow components. See Figure 1 for an illustration of the Letdown Nozzle FSWOL.

A FSWOL is 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. A full structural weld overlay can be either mitigative or repair weld overlay as defined below:

Mitigative weld overlay is a weld overlay that is applied over material with no inside-surface-connected flaws found during an examination performed in accordance with ASME Section XI, Appendix VIII, Supplement 10 or Supplement 2, as applicable.

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

The weld overlay to be applied to the Letdown nozzle DMW would therefore be characterized as a full structural repair weld overlay since it will be applied without the benefit of a pre-weld overlay examination.

ONS will be inspecting the core flood (CF) and reactor coolant pump (RCP) inlet and outlet (I/O) nozzle Alloy 82/182 butt welds with Performance Demonstration Initiative (PDI) volumetric examination techniques. If indication(s) are identified in any of the core flood (CF) or reactor coolant pump (RCP) inlet and outlet (I/o) inspection volumes, ONS will be evaluating them per ASME Code Section XI criteria for acceptability. If the indication(s) require repair, they will be repaired by, first, a local repair or second, a FSWOL.

Currently, there are no comprehensive criteria for a licensee to apply a full structural weld overlay to DMW constructed of Alloy 82/182 weld material. Neither the latest NRC approved edition nor the edition of ASME Section XI used for the Oconee Units 1, 2, and 3 repair/replacement program contains the needed requirements for this type of repair.

Repair/replacement activities associated with a full structural weld overlay repair of this type are required to address the materials, welding parameters, ALARA concerns, operational constraints, examination techniques, and procedure requirements. Similar weld overlays have.

been applied to other plants since 1986 with no problems identified.

5.0 PROPOSED ALTERNATIVES AND BASIS FOR USE Pursuant to IOCFR 50.55a (a) (3) (i), an alternative to the requirements listed in Section 3.0 above is requested on the basis that the proposed alternative will provide an acceptable level of quality and safety. Attachment 1, Tables Al, A2 and A3, included as a part of this request for relief, provide details of relief requested from each of these requirements.

Page 5 of 34

Request No. 09-ON-003 The CF and RCP 1/0 FSWOLs are a contingency option only. Duke Energy is asking for NRC pre-approval of the FSWOL for the CF and RCP 1/0 nozzles in the current Relief Request should indications be identified during the inspection and subsequent qualification is not possible and local repair options are not applicable for the specific indication identified.

The overlays will extend around the full circumference of the welds, as illustrated in Figures 2 through 5. The FSWOLs are sized to satisfy the ASME Code,Section III requirements without crediting the existing welds.

All proposed weld overlay designs are consistent with the requirements of ASME Code Case N-504-3 [3] and Section XI, Nonmandatory Appendix Q [4], with the modifications noted in, Table Al. The provisions of Appendix Q must be met as a condition of acceptance of the Code Case by NRC Regulatory Guide 1.147, Revision 15. The specific thickness and length are computed according to the guidance provided in Code Case N-504-3 and Appendix Q. The overlay will completely cover the Alloy 82/182 welds with Alloy 52M/52MS material that is highly resistant to PWSCC.

The length of the full structural weld overlay is sized for inspection of the volume shown in Appendix Q, Fig Q-4300-1. This volume extends '/2-inch beyond the susceptible weld and includes the outer 25% of the original wall thickness. When necessary, for DMWs adjacent to Carbon Steel (CS) nozzles, the length of the FSWOL is extended and blended into the CS nozzle outer diameter to permit Ultrasonic Testing (UT) of the weld and to minimize stress concentration on the nozzle outer diameter.. The outside diameter of the nozzle is larger than that of the adjacent component; therefore, the FSWOL thickness on the component is increased to allow a smooth transition surface for UT. The final structural weld overlay length and thickness after taking into consideration the UT requirements may exceed the length required for a full structural weld overlay repair in accordance with Code Case N-504-3 and Appendix Q. To the greatest extent possible, the FSWOLs will not limit the examination of the adjacent carbon steel or stainless steel welds.

ASME Boiler and Pressure Vessel Code Section XI, 1998 Edition, with Addenda through 2000 [1] (i.e., the Code Edition applicable to the fourth inspection interval for Units 1, 2, and 3 and for which relief is requested) requires performance of Nondestructive Examination (NDE) and specifies the methods and acceptance criteria. As an alternative to the Section XI NDE requirements, Duke Energy will follow the NDE requirements of Appendix Q [4] for the required NDE. The bases for these alternatives are shown as needed in Attachment 1, Table Al.

Appendix Q, Article 4000 requires ultrasonic examination procedures and personnel to be qualified in accordance with ASME Code,Section XI, Appendix VIII. Ultrasonic examination of the completed FSWOL will be accomplished in accordance with Section XI, Appendix VIII, Supplement 11 [2], with alternatives to comply with the Performance Demonstration Initiative (PDI) program as shown in Table A2.

The welding will be performed using a machine Gas Tungsten Arc Welding (GTAW) process and using the ambient temperature temper bead method with ERNiCrFe-7A (Alloy 52M) weld metal. Manual GTAW, using ERNiCrFe-7 (Alloy 52) or Alloy 52M may be used if Page 6 of 34

Request No. 09-ON-003 local repairs of weld defects are necessary or additional weld metal is required locally to form the final FSWOL contour in locations at least 3/16 in. away from the low alloy or carbon steel nozzles.

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

of the assemblies in some cases. The flaw characteristics observed above are indicative of hot cracking. This phenomenon has not been observed on the ferritic steel or ENiCrFe-3 (Alloy 182) DMW portions of the assemblies when welding Alloy 52M thereon. Further studies have determined that this problem nay occur when using Alloy 52M filler metal on austenitic stainless steel materials with high sulfur content. Extensive tests and field experience from Welding Service Inc. (WSI) indicate that hot cracking can be a concern when the sulfur and phosphorus content in the diluted weld puddle equals or exceeds 0.014%. The impurity hot cracking' threshold level is a function of both the composition of the weld filler materials and the welding parameters that are used because these two factors control the dilution of the solidified weld deposit. This suggests that a combined sulfur plus phosphorus content of the base material approximately 0.046% will represent a threshold for hot cracking with the weld parameters WSI will use at Oconee. Oconee Units 1, 2 and 3 will use a barrier layer on all the stainless steel items prior to overlay. The barrier layer will use ER308L or ER309L on the stainless steel and will use Alloy 82 to transition from the end of the stainless steel into the DMW. The barrier layer will not be used in the structural analysis.

The FSWOL will be applied over portions of the CS components. The Construction Code requires either pre-heat or post-weld heat treatment after welding depending on the carbon content or base material thickness. As an alternative to pre-heat or post-weld heat treatment, the overlay will be implemented in accordance with Code Case N-638-1 with the modifications noted in Table A3 of Attachment 1. Code Case N-638-1 was conditionally approved for generic use in NRC Regulatory Guide 1.147, Revision 15, and was developed for welding similar and dissimilar metals using the ambient temperature machine GTAW temper bead technique. This Code Case specifies a limit of 100 square inches for the surface area of temper bead weld over the ferritic material. The maximum weld surface areas over ferritic material for the subject weld overlays are expected to be approximately 700 square inches for the RCP Suction/Discharge lines.

An ASME white paper describes the technical justification for allowing increased overlay areas up to 500 square inches [Ref. 6]. The white paper indicates the original limit of 100 square inches in Code Case N-638-1 was an arbitrary limit and goes on to justify the application of overlays up to 500 square inches on ferritic low alloy steel. The white paper was also submitted to the NRC as a part of a relief request by Constellation Energy Generation Group (Adams Accession Number, ML060240110) [7]. The white paper cites evaluations of a 28 inch diameter nozzle weld overlay to demonstrate adequate tempering of the weld heat affected zone (Section 2a of the white paper), residual stress evaluations demonstrating acceptable residual stresses in weld overlays ranging from 100 to 500 square inches (Section 2b of the white paper), and service history in which weld repairs exceeding Page 7 of 34

Request No. 09-ON-003 Enclosure I 100 square inches were NRC approved and applied to nozzle DMW in several BWRs and three PWRs (Section 3c of the white paper). Some of the cited repairs are greater than 15 years old, and have been inspected several times with no evidence of any continued degradation.

There are three potential technical concerns that the 100 square inches limitation may have been intended to prevent: residual stresses, tempering of the weld Heat Affected Zone (HAZ),

and the possible (but unlikely development) of delayed hydrogen cracking in the underlying ferritic base material. These potential concerns are addressed below:

(a) Residual Stresses -Using as an example BWR Feedwater Nozzle, the white paper cites EPRI sponsored analyses [8] of an overlay that just equaled 100 square inches coverage over the ferritic steel base metal. Two axisymmetric finite element models were created, one with the 100 square inches weld overlay and the other with the weld overlay extended on the nozzle side until it blended into the nozzle taper surface (approximately 126 square inches).

The paper states that the extended overlay configuration did not significantly alter the residual stress results, and if anything, made the axial stresses even more compressive.

(b) HAZ Tempering -The white paper cites past programs which have demonstrated that temper bead welding using automatic GTAW provides adequate tempering of the HAZ in P-1 and P-3 materials and does not degrade strength or fracture toughness for temper bead weld overlays. Reference [9] presents results of a bimetallic weld overlay mockup of a 12 inch diameter, SA-508 Class 2 low alloy steel nozzle. Microstructure and microhardness measurements were performed on the HAZ of this overlay, as well as mechanical property tests (Charpy) of a groove weld in the same nozzle with similar coverage area. The mechanical property results verified that the weld overlay repair did not degrade the strength or toughness of the low alloy steel HAZ. Microstructure and microhardness results-demonstrated adequate tempering of the material, such that hydrogen embrittlement would not be expected.

(c) Delayed Hydrogen Cracking -Inspections of the above described mockup, as well as extensive inspections of temper bead weld overlays in mockups and in the field, have been performed on overlays with low alloy steel coverage's ranging from less than 10 square inches up to and including 325 square inches. These have shown that hydrogen induced cracking has not been a problem with repairs produced by the automatic GTAW temper bead process. The process is by its nature a low hydrogen process, and diffusion of hydrogen is very rapid for low alloy steels. Nonetheless, the post weld soak specified in the ASME Code is intended as a post hydrogen bake out permitting NDE after the repair has returned to ambient temperature. Code Case N-638-1, since it does not impose the post weld bake, requires a 48-hour hold time prior to NDE, to verify that the unlikely event of hydrogen induced cold cracking has not occurred. Extensive research has been performed by EPRI (Technical Report 1013558, Temper Bead Welding Applications 48 Hour Hold Requirements for Ambient Temperature Temper Bead Welding) which provides a technical basis for Page 8 of 34

Request No. 09-ON-003 Enclosure I starting the 48-hour hold after completing the third temper bead weld layer rather than waiting for the weld overlay to cool to ambient temperature. The hold time required by Code Case N-638-1 will be implemented in accordance with this latest research. This approach has been previously reviewed and approved by the NRC [Ref. 10, 11]. Furthermore, the metallurgical aspects discussed above are independent of the surface area of the repair but related.to paramieters of the qualified welding procedure.

Finally, it is important to note that the above theoretical arguments have been proven in practice by extensive field experience with temper bead weld overlays, with coverage ranging from less than 10 square inches up to and including 325 square inches. Table 5.1 below provides a partial list of such applications. It is seen from this table that the original DMW weld overlay was applied over 20 years ago, and WOLs with low alloy steel coverage in the 100 square inches range have been in service for 5 to 15 years. Several overlays have been applied with low alloy steel coverage significantly greater than the 100 square inches. Relief requests for these large overlays have been previously approved. These overlays have been examined with PDI qualified techniques, in some cases multiple times, and none have shown any signs of new cracking or growth of existing cracks.

Also, the overall conclusions from EPRI report NP-10 11898 [8] states "The restriction on surface area for temper bead welding was arbitrary, is overly restrictive, leads to increased cost and dose for repairs and does not contribute to safety. There is no direct correlation of residual stresses with surface area of the repair either for cavity or overlay repairs done using temper bead welding. Cases have been analyzed up to 500 square inches that verify that residual stresses for cavity repairs remain compressive in the weld region for larger area repairs as well as for smaller area repairs". Based on all of the above, relief from the requirement of a maximum of 100 square inches of overlay on the ferritic base metal up to 700 square inches is justified.

Temperature monitoring required by Code Case N-638-1 will be performed using temporarily attached or contact pyrometers and manual data recording in lieu of thermocouples and recording equipment required by IWA-4610(a) of Section XI. The thermocouple pyrometers proposed for use are calibrated in accordance with the suppliers QA program approved by Duke Energy and will provide temperature information equivalent to that obtained from weld attached thermocouples. Control of interpass temperature as required by Code Case N-638-1 will be met by the proposed technique. This exception has been permitted by the NRC in the past (see precedent 6 in Para. 8.0 below). As described in Attachment 1, Table A3, use of pyrometers will provide acceptable temperature monitoring for application of the FSWOL.

In addition to the ultrasonic examination of a 1.5T band of material on each end of the weld, the conditional approval of Code Case N-638-1 imposes a condition that the ultrasonic examination be qualified on samples using construction type flaws and that the acceptance criteria be in accordance with NB-5330 of Section III of the ASME Boiler and Pressure Vessel Code. In lieu of this requirement, Duke Energy proposes to use a PDI qualified Page 9 of 34

Request No. 09-ON-003 ultrasonic examination procedure that is designed and qualified to examine the entire volume of the overlay weld as well as the region of the carbon steel material containing the weld HAZ and a volmne of unaffected base material beyond the HAZ.

Code Case N-638-1 addresses the use of the temper bead welding technique including those welds made in deep cavities in ferritic material. In the case of weld overlays to be applied at ONS, this technique will be used to apply a non-ferritic overlay to the ferritic base material adjacent to the DMW. Duke Energy's examination of the weld will verify the soundness and assure that delayed cracking potentially caused by hydrogen introduced during the temper bead welding process is not present. In the unlikely event that this type of cracking does occur, it would be initiated on the surface on which the welding is actually performed or in the HAZ immediately adjacent to the weld. The most appropriate technique to detect surface cracking is the surface examination technique that Duke Energy will perform on the weld overlay and the adjacent base material in a band at least 1.5 times the thickness of the base material on either side of the overlay. The combined UT and surface inspection will cover 100% of the area susceptible to weld induced defects. While it would be possible with additional expenditure of time and equipment to extend the examination volume to a larger extent on either side of the weld overlay, it would not be possible with current technology to ultrasonically inspect 100% of the volume within 1.5 times the thickness of the base material because of geometric considerations. Inspection of an increased volume would result in increased dose to inspection personnel without a compensating increase in safety or quality because there is no plausible mechanism for formation of new flaws or propagation of existing flaws into the region. That is, any expanded inspection would be performed on material that would not otherwise be inspected as part of an ASME Section XI or ASME Section III required weld examination. The overlay volume is small relative to the volume of the underlying pipe and does not present the same concerns as those related to welds in deep cavities contemplated by the requirements of Code Case N-638-1. Therefore, the examinations tailored for overlay inspection and required by Code Case N-504-3 and ASME Section XI, Appendix Q as modified in the request for relief provide full assurance that the weld and adjoining base material are fully capable of performing their intended pressure retaining safety function.

ASME Section XI pre-service acceptance standards, as specified in Appendix Q, are the appropriate standards for pre-service ultrasonic examinations of weld overlay repairs to nuclear plant components. These standards are consistent with the highly sensitive ultrasonic examination procedures being used, which are qualified in accordance with ASME Section XI, Appendix VIII, Supplement 11, as implemented via the EPRI PDI. The post-repair inspection volume includes the full thickness of the weld overlay plus 25% of the underlying base metal weldment thickness. The specimen sets for PDI qualification of weld overlay examinations include construction type flaws in the overlays in addition to simulated service flaws in the underlying base metal and weldment. Therefore, use of PDI-qualified personnel and procedures will result in the reliable detection of construction type flaws.

Page 10 of 34

Request No. 09-ON-003 The ASME Section XI flaw acceptance standards are based on fracture mechanics principles that evaluate the potential effect of flaw indications on the safe operation of a component.

ASME Section III ultrasonic standards, on the other hand, are derived from radiographic standards in earlier Construction Codes and tend to be workmanship-based, addressing flaws occurring in the original construction process that are likely to be detected by radiography.

The ASME Section III acceptance criteria do not allow the presence of any cracks or crack-like indications, regardless of their size, and are geared more towards construction-type welds.

Many indications that are detectable by PDI qualified ultrasonic techniques, and thus require evaluation, would not be detected by the radiographic examinations required by the original construction Code or Section III. It is therefore not reasonable, not-technically logical, to reject such indications based on out-dated, workmanship-based standards when found by much more sensitive examination techniques that are not required by the construction Codes.

The Section XI pre-service examination standards were developed for exactly the above-stated reasons, and consider the materials in which the flaw indications are detected, the orientation and size of the indications, and ultimately their potential structural impact on the component. They are the logical choice for evaluation of potential flaw indications in post-overlay examinations, in which unnecessary repairs to the overlays would result in additional personnel radiation exposure without a compensating increase in safety and quality, and could potentially degrade the effectiveness of the overlays by affecting the favorable compressive residual stress field that they produce.

Acceptance of ultrasonic indications in weld overlay repairs using Section XI acceptance criteria has been approved by NRC in past weld overlay applications (e.g. Precedents 8 and 9) in paragraph 8.0 below.

The following information for all implemented FSWOLs will be submitted to the NRC within fourteen days of completion of the final UT on each unit included in this relief request.

a listing of flaw indications detected

• the disposition of all indications using the standards of ASME Section XI, IWB-3514-2 and/or IWB-3 514-3 criteria and, if possible, 2

the type and nature of the indications The recording criteria of the ultrasonic examination procedure to be used for the examination of the Oconee weld overlays requires that all suspected flaw indications, regardless of amplitude, be investigated to the extent necessary to provide accurate characterization identity, and location. Additionally, the procedure requires that all indications, regardless of amplitude, that cannot be clearly attributed to the geometry of the overlay configuration be considered flaw indications.

2The ultrasonic examination procedure states that all suspected flaw indications should be plotted on a cross sectional drawing of the weld and that the specific origin of the reflector be accurately identified.

Page 11 of 34

Request No. 09-ON-003 Enclosure I Also included in the results will be a discussion of any repairs to the overlay material and/or base metal and the reason for the repair.

Subsequent Inservice examination of the structural weld overlays on the overlaid nozzles will be in accordance with ASME Section XI, Appendix Q, Q-4300 [4].

In summary, this Request for Alternative requests relief from portions of the applicable ASME Code and Code Cases approved for use by the NRC. There are no new or different approaches in this overlay design that are considered first of a kind or inconsistent with previous applications. The overlay is designed as a full structural overlay in accordance with ASME Code Case N-504-3 and Section XI, Nonmandatory Appendix Q.

Page 12 of 34

Request No. 09-ON-003 Table 5.1 Dissimilar Metal Weld Overlay Experience Nozzle Date Plant Component Diameter (in)

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

May 2008 SCANA/V. C. Summer PZR Surge Nozzle 12 PZR Spray Nozzle 4

PZR Safety/Relief Nozzles 6

May 2008 Entergy/Waterford-3 PZR Surge Nozzle 12 PZR Spray Nozzle 4

PZR Safety/Relief Nozzles 6

HL Drain 2

HL Surge 12 HL Shutdown Cooling 14 April 2008 APS/Palo Verde-2 PZR Surge Nozzle 12 PZR Spray Nozzle 4

PZR Safety/Relief Nozzles 6

HL Surge Nozzle 12 HL Shutdown Cooling Nozzle 16 April 2008 Duke Energy Decay Heat Nozzle 12 Energy/Oconee-I April 2008 Dominion/Millstone-2 Shutdown Cooling Nozzle 12 Safety Injection Nozzles 12 RCS Spray Nozzle 3.5 Charging Inlet Nozzles 2

April 2008 STPNOC/STP-I PZR Surge Nozzle 16 PZR Spray Nozzle 6

PZR Safety/Relief Nozzles 6

March 2008 Entergy/ANO-2 HL Drain Nozzle 2

HL Shutdown Cooling Nozzle 14, HL Surge Nozzle 12 January 2008 FENOC/Davis-Besse PZR Surge Nozzle 10 PZR Spray Nozzle 4

PZR Safety/Relief Nozzles 2.5/3.0 HL Surge Nozzle 10 HL Decay Heat Nozzle 12 December 2007 SCE/SONGS 2 PZR surge nozzle 12 November 2007 Duke Energy/Oconee 3 PZR spray nozzle 4

safety/relief nozzles 4.5 PZR surge nozzle 10 November 2007 APS / Palo Verde 3 PZR spray nozzle 4

safety/relief nozzles 6

PZR surge nozzle 12 October 2007 SCE/SONGS 3 PZR surge nozzle 12 Page 13 of 34

Request No. 09-ON-003 Enclosure I Table 5.1 Dissimilar Metal Weld Overlay Experience (cont)

Nozzle Date Plant Component Diameter (in)

[See notel October 2007 Duke Energy / Catawba PZR spray nozzle 4

safety/relief nozzles 6

PZR suLige nozzle 14 October 2007 PSEG/Hope Creek Recirc Inlet nozzle 10 October 2007 TVA Sequoyah I PZR spray nozzle 4

safety/relief nozzles 6

PZR surge nozzle 12 October 2007 Tai Power / Kuosheng 2 Recirc Inlet nozzle 10 September 2007 Progress / Harris PZR spray nozzle 4

safety/relief nozzles 6

PZR surge nozzle 14 June 2007 APS / Palo Verde I PZR spray nozzle 4

safety/relief nozzles 6

PZR surge nozzle 12 May 2007 Entergy / ANO 1 PZR spray nozzle 4

safety/relief nozzles 4.5 PZR surge nozzle 10 May 2007 Duke Energy/Oconee 2 PZR spray nozzle 4

safety/relief nozzles 4.5 PZR surge nozzle 10 April 2007 Duke Energy/McGuire I PZR spray nozzle 4

safety/relief nozzles 6

PZR surge nozzle 14 April 2007 STPNOC/South Texas 2 PZR spray nozzle 6

safety/relief nozzles 6

PZR surge nozzle 16 March 2007 FPL/Duane Arnold Recirc. Inlet nozzles 10 March 2007 TPC/Chin Shan Recirc Outlet nozzle 23 March 2007 Entergy/Pilgrim Recirc. Inlet nozzle 10 December 2006 TVA/Sequoyah 2 PZR spray nozzle 4

safety/relief nozzles 6

PZR surge nozzle 14 November 2006 SCE/SONGS Unit 3 PZR spray nozzle 5.1875 safety/relief nozzles 8

PZR surge nozzle 12.75 November 2006 Duke Energy/Catawba PZR spray nozzle 4

Unit I safety/relief nozzles

'6 PZR surge nozzle 14 Page 14 of 34

Request No. 09-ON-003 Enclosure I Table 5.1 Dissimilar Metal Weld Overlay Experience (concluded)

Nozzle Date Plant Component Diameter (in) 2

[See notel November 2006 Duke Energy/Oconee PZR spray nozzle 4.5 Unit I safety/relief nozzles 4.5 PZR surge nozzle 10.875 HL Surge Nozzle 10.75 October 2006 Duke Energy/McGuire PZR spray nozzle 4

Unit 2 safety/relief nozzles 6

PZR surge nozzle 14 April 2006 FENOC/Davis-Besse Hot leg drain nozzle 4

February 2006 SCE/SONGS Unit 2 PZR spray nozzle 8

safety/relief nozzles 6

November 2005 TPC/Kuosheng Unit 2 Recirculation outlet nozzle 22 April 2004 PPL/Susquehanna Unit I Recirc. inlet nozzle 12 Recirc. outlet nozzle 28 November 2003 AmerGen/TMI Unit I Surge line nozzle 11.5 October 2003 Entergy /Pilgrim Core spray nozzle 10 CRD return nozzle 5

October 2002 Exelon/Peach Bottom Core spray nozzle 10 Units 2 and 3 Recirc. outlet nozzle 28 CRD return nozzle 5

October 2002 AmerGen /Oyster Creek Recirc. outlet nozzle 26 December 1999 FPL/Duane Arnold Recirc. inlet nozzle 12 June 1999 FENOC /Perry Feedwater nozzle 12 June 1998 CEG/Nine Mile Point Feedwater nozzle 12 Unit 2 March 1996 Progress/Brunswick Units Feedwater nozzle 12 1 and 2 February 1996 Southern/Hatch Unit I Recirc. inlet nozzle 12 January 1991 Entergy/River Bend Feedwater nozzle 12 March 1986 Entergy/Vermnont Yankee Core spray nozzle 10 Note: The total area of overlay on the low alloy steel varies widely from about 16 square inches on the smaller diameter nozzles such as drain nozzles to about 325 square inches on the larger diameter components such as recirculation outlet nozzles.

Page 15 of 34

Request No. 09-ON-003 Enclosure I 6.0 WELD OVERLAY DESIGN AND VERIFICATION The design of these weld overlays takes guidance from the requirements of ASME Code Case N-504-3, and Code Case N-638-1, with modifications as described above in Section 5.0 and in the attached tables. The analyses performed are bounding for all three Oconee units and demonstrate the modifications are long-term repairs and mitigation of PWSCC at each of the locations considered in the analysis. The fundamental design basis for FSWOLs is to maintain the original safety margins of the welds, with no credit taken for the underlying PWSCC susceptible weldments. The design basis flaw for the purpose of structural sizing of the overlay is assumed to be 360 degrees and 100% through the original wall thickness of the DMW. For the crack growth analysis the initial flaw size is assumed to be 360 degrees and 75% through the original wall thickness. The 75% through-wall assumption is selected based upon the PDI-qualified inspection of the overlay at the conclusion of the weld overlay process, which includes the outer 25% of the original weld. If flaws are detected in the post-overlay inspection, they will be evaluated in accordance with the requirements of Code Case N-504-3 and Appendix Q. Analyses will demonstrate that the overlay designs meet the requirements of the ASME Code Case N-504-3 for full structural weld overlays. Following is a listing of the analyses and verifications that will be performed for each overlay.

I. Configuration specific stress analyses will be performed to establish a residual stress profile in the DMW. Severe ID weld repairs that effectively bound any actual DMW repairs will be assumed. The weld overlay is subsequently applied in the finite element model to simulate the final residual stress profile. Post weld overlay residual stresses at normal operating conditions will then be shown to result in beneficial compressive stresses on the inside surface of the components, further assuring that crack growth into the overlay is highly unlikely.

2. Fracture mechanics analyses will also be performed to predict crack growth, assuming that cracks exist that are equal to or greater than the thresholds of the NDE techniques to be used on the DMW. Potential crack growth will be evaluated due to PWSCC as well as due to fatigue crack growth in the original DMW. The crack growth analyses will consider all design loads and transients, plus the post weld overlay residual stress distributions, and will demonstrate that cracks will not grow beyond the original DMW thickness for the time period until the next scheduled inservice inspection.

3. The original Leak-Before-Break calculations will be updated with an evaluation demonstrating that due to the efficiency of the overlay for PWSCC mitigation, concerns for original weld susceptibility to cracking have been resolved.

4. The analyses will demonstrate that application of the weld overlays does not impact the conclusions of the existing nozzle Stress Reports. ASME Code,Section III stress and fatigue criteria will be met, as spelled out in ASME Code Case N-504-3.

5. Shrinkage will be measured during the overlay application. Axial shrinkage is measured during weld overlay application by measuring the distance between punch marks in the base material just outside of the weld overlay before and after overlay Page 16 of 34

Request No. 09-ON-003 Enclosure I application. Shrinkage stresses at other locations in the piping systems arising from the weld overlays will be demonstrated not to have an adverse effect on the systems.

Clearances of affected support and restraints will be checked after the overlay repair, and will be reset within the design ranges as required.

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

7. The as-built dimensions of the weld overlays Will be measured and evaluated to demonstrate that they equal or exceed the minimum design dimensions of the overlays.

Summaries of the results of the analyses listed in items 1 through 4 above will be submitted to the NRC prior to entry into mode 6 during the restart of Oconee Unit 1 during the EOC 25 (Fall 2009) outage. Items 5 through 7 above will be completed prior to entry into Mode 6 during the restart of each of the Oconee Units. All analyses and data will be available for review by the NRC resident or field inspectors as needed. These analyses and summaries are.

for the Letdown.nozzle FSWOL only. Only if the FSWOL is installed on any of the CF or RCP I/O nozzles, will the similar information be available. If the FSWOL is installed on the CF or RCP I/O nozzles, the fracture mechanics results Will be made available within 60 days of startup from the outage.

7.0 DURATION OF THE PROPOSED ALTERNATIVES These structural weld overlays will remain in place for the design life of the repair that is defined by the evaluation required in paragraph (g) of Code Case N-504-3 and corresponding requirements in Nonmandatory Appendix Q. The overlays will be performed during the fourth inspection interval for the three Oconee units. The interval start and end dates for these units are:

Oconee Unit 1-Start: 01/01/2004 End: 07/15/2013 Oconee Unit 2-Start: 09/09/2004 End: 09/08/2014 Oconee Unit 3-Start: 01/02/2005 End: 12/15/2015 The Code of Record for'inservice inspection during these intervals is the ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda for all three units.

8.0 PRECEDENTS

1.

Letter from Richard J. Laufer, NRC, to Christopher M. Crane, AmerGen, "Three Mile Island Nuclear Station, Unit 1 (TMI-1) Request for Relief from Flaw Removal, Heat Treatment, and Nondestructive Examination Requirements for the Third 10-year Inservice Inspection (ISI) Interval (TAC.No. MC 1201)," Accession Number ML041670510, dated July 21, 2004.

Page 17 of 34

Request No. 09-ON-003

2.

Letter from Richard J. Laufer, NRC, to Bryce L. Shriver, PPL Susquehanna, "Susquehanna Steam Electric Station, Unit I - Relief fromn American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code),Section XI, Appendix VIII, Supplement 11, Requirements and Code Cases N-504-2 and N-638 Requirements (TAC Nos. MC2450, MC2451 and MC2594)," Accession Number ML051220568, dated June 22, 2005.

3.

Letter from L. Raghavan, NRC, to Mano K. Nazar, I&M, "Donald C. Cook Nuclear Plant, Unit I - Alternative to Repair Requirements of Section XI of the American Society of Mechanical Engineers Code (TAC No. MC0675 1)," Accession Number ML051720006, dated June 27, 2005.

4.

Letter from Richard J. Laufer, NRC, to George Vanderheyden, Calvert Cliffs, "Calvert Cliffs Nuclear Power Plant, Unit No. 2 - Relief Request for Use Weld Overlay and Associated Alternative Inspection Techniques (TAC Nos. MC6219 and MC6220),"

Accession Number ML051930316, dated July 20, 2005.

5.

Letter from Darrell J. Roberts, NRC, to David A. Christian Dominion Nuclear Connecticut, Inc., "Millstone Power Station, Unit No. 3 - Issuance of Relief from Code Requirements (TAC No. MC8609)," Accession Number ML053260012,.dated January 20, 2006.

6.

Southern California Edison's San Onofre Unit 2 Request for Relief from the Requirements of the ASME Code, approved December 14, 2006.

7.

Davis-Besse Unit 1,Evaluation of Request for Relief Re: Full Structural Weld Overlay, approved October 19, 2006.

8.

Duke Energy Corporation, Request for Relief 06-ON-004, for Oconee Unit 1, approved August 6, 2007.

9.

Duke Energy Corporation, Request for Relief 06-GO-001, for McGuire Unit 2, approved July 25, 2007'.

10.

Duke Energy Corporation, Request for Relief 06-GO-00 1, for Catawba Unit 1, approved July 25, 2007.

11.

Duke Energy Corporation, Request for Relief 07-ON-004, for Oconee Units 1,2and3, approved January 17, 2008.

Page 18 of 34

Request No. 09-ON-003 Enclosure I

9.0 REFERENCES

(1)

ASME Code,Section XI, 1998 Edition through 2000 Addenda, IWA-4000.

(2)

ASME Code,Section XI, 1998 Edition through 2000 Addenda, Mandatory Appendix VIII, Supplement 11.

(3)

ASME Code Case N-504-3, Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping,Section XI, Division 1, August 4, 2004.

(4)

ASME Code Section XI, 2004 Edition with Addenda through 2006, Nonmandatory Appendix Q, Weld Overlay Repair of Class 1,2, and 3 Austenitic Stainless Steel Piping Weldments.

(5)

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

(6)

ASME Code Case N-638-3, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1, April 18, 2006 and accompanying white paper.

(7)

Calvert Cliffs, Units I and 2 - ASME Section XI Relief Request to Use Weld Overlay and Associated Alternative Techniques, Accession Number ML060240110, dated January 18, 2006.

(8)

"Justification for the Removal of the 100 Square Inch Limitation for Ambient Temperature Temper Bead Welding on P-3 Material", EPRI-NP-1011898, February 2005.

(9)

"Inconel Weld-Overlay Repair for Low-Alloy Steel Nozzle to Safe-End Joint",

EPRI NP-7085-D, January 1991.

(10)

Safety Evaluation by the Office of Nuclear Reactor Regulation related to the Three Mile Island Nuclear Station, Unit 1 (TMI-1) Request for Relief from Flaw Removal, Heat Treatment and Nondestructive Examination (NDE) Requirements for the Third 10-Year Inservice Inspection (ISI) Interval, Amergen Energy Company, LLC Docket No. 50-289, July 21, 2004.

(11)

Safety Evaluation By the Office of Nuclear Reactor Regulation Related to ASME Code,Section XI, Alternatives for Union Electric Company Callaway Plant, Unit 1, Docket No. 50-483, July 10, 2007.

Page 19 of 34

Request No. 09-ON-003

10.0 CONCLUSION

Duke Energy concludes that the alternative repair approach described above presents an acceptable level of quality and safety to satisfy the requirements of 10 CFR 50.55a(a)(3)(i).

The approach described in this relief request includes evaluation of available operating experience related to previously NRC approved applications of overlays to DMW.

This Relief Request addresses a FSWOL for the Letdown Line and contingency overlay designs for the RCP suction/discharge and CF nozzles.

Page 20 of 34

Request No. 09-ON-003 Enclosure I Weld Overlay SS Cladding 09003rl Figure 1: Letdown Line Nozzle Weld Overlay (Schematic)

Weld Overlay LAS Nozzle SS Cladding 09002r0 Figure 2: Core Flood Nozzle Weld Overlay (Schematic)

Page 21 of 34

/

Request No. 09-ON-003 Enclosure I Weld Overlay SS Cladding 0900610 Figure 3: Unit I RCP Suction Weld Overlay (Schematic)

Weld Overlay SS Cladding Butter 09004rl Figure 4: Unit 2 and 3 RCP Suction Weld Overlay (Schematic)

Page 22 of 34

Request No. 09-ON-003 Enclosure I Weld Overlay SS Cladding Butter 09005r0 Figure 5: RCP Discharge Weld Overlay (Schematic)

Page 23 of 34

Request No. 09-ON-003 Enclosure I ATTACHMENT 1 CONTENTS Table Al Modifications to Code Case N-504-3 and Corresponding Nonmandatory Appendix Q Requirements Table A2 Alternatives to Appendix VIII, Supplement 11 Table A3 Modifications to Code Case N-638-1 Page 24 of 34

Request No. 09-ON-003 Enclosure I Table Al ModificationsTo Code Case N-504-3 and Corresponding Nonmandatory Appendix Q Requirements Code Case N-504-3 Modification/Basis Reply: It is the opinion of the Committee that, in lieu of the requirements of IWA-4120 in Editions and Addenda up to and including the 1989 Edition with the 1990 Addenda, in IWA-4170(b) in the 1989 Edition with the 1991 Addenda up to and including the 1995 Edition, and in IWA-4410 in the 1995 Edition with the 1995 Addenda up to and including the 1996 Addenda, and in IWA-4420 in the 1995 Edition with the 1997 Addenda and later Editions and Addenda, in I WA-48 10(a) in the 1992 Edition with the 1994 Addenda through the 1995 Edition, and in IWA-4520(a) in the 1995 Edition with the 1995 Addenda and later Editions and Addenda, a defect in austenitic stainless steel piping may be reduced to a flaw of acceptable size in accordance with IWB-3640 from the 1983 Edition with the Winter 1985 Addenda, or later Editions and Addenda, by deposition of weld reinforcement (weld overlay) on the outside surface of the pipe, provided the following requirements are met. [Essentially same as Scope of Appendix QI:

Modification. Code Case N-504-3 will be used for weld overlay repairs to the ferritic and nickel alloy base material as well as the autstenitic stainless steel base material.

Basis: Code Case N-504-3 is accepted for use in the current NRC Regulatory Guide 1. 147 Rev. I provided the additional requirements of Noninandatoly Appendix Q are met. For the weld overlay qf the identified welds at Oconee Units 1, 2 and 3 the base material will beferritic material with existing nickel alloy weld metal to which an austenitic stainless steel or Alloy 600 safe end is welded Industry operational experience has showin that PWKSCC in Alloy 82/182 will blunt at the interface with stainless steel base metal, ferritic base metal. or Alloy 52/52M/52MS weld metal. The 360° structural weld overlay' will control growth in any PWSCC crack and maintain weld integrity. The weld overlay will induce compressive stress in the weld, thus impeding growth of any reasonably shallow cracks. Furthermore, the overlay will be sized to meet all struclural requirements independent of the existing weld

• (b) Reinforcement weld metal shall be low carbon (0.035% max.) austenitic stainless steel applied 3600 around the circumference of the pipe, and shall be deposited in accordance with a qualified welding procedure specification identified in the Repair Program. The submerged arc method shall not be used for weld overlay.[Same as Q-2000(a)I.

Modification. In lieu ofaustenitic stainless steel filler material, the reinforcement weld metal will be a nickel alloy.

Basis: The weld metal used may be ERNiCrFe-7A (Al/oy 52M, UNS N06054) or ERNiCrFe-7 (Alloy 52 UNS N06052). This weld metal is assigned F43 by ASAE per Code Case 2142-2. The requirements of ASAMIE Section III, NB-2400 will be applied to all filler muaterial. The chromium content o/ Alloy 52M/IS is 28-31.5%, identical to that ofAlloy 52. The main cdfwerence in Alloy 52 vs. Alloy 52M/MS is a higher Niobiumn content (0.5-1 %). The diflerence in chemical composition between Alloy 52 and Alloy 52M/MAIS improves the weldability of the material and pins the grain boundaries thus preventing separation between the grains and hot tearing during weld puddle soliclificac ion. Thesefiller muaterials were selected for their improved resistance to P PVSCC. Alloys 52 and 52AM/MA1S contain about 30% chromium that imparts excellent corrosion resistance. The existing Alloy 82/182 weld and the Alloy 52AMl/52MS overlaty are nickel base and have ductile properties and toughness similar to austenitic stainless steel piping welds at pressurized water reactor operating temperature. Thesefiller materials are suitable for welding over the ferritic nozle, nickel alloy weld or base muaterial, and the austenitic stainless steel safe end or pipe components.

Page 25 of 34

Request No. 09-ON-003 Enclosure I Table Al:

Modifications To Code Case N-504-3 and Corresponding Nonmandatory Appendix Q Requirements Code Case N-504-3 Modification/Basis (e) The weld reinforcement shall consist ofa minimum of two weld layers Modification: Delta ferrite (EN) measurements will not be performed for weld

.having as-deposited delta ferrite content of at least 7.5 FN. The first layer of weld overlayirepairs ta f Allo measurems wel m etal.

metal with delta ferrite content of least 7.5 FN shall constitute the first layer of overlay repairs made of Alloy 52/52M/52MS weld metal.

the weld reinforcement design thickness. Alternatively, first layers of at least 5 Basis: Welds of Alloy52t52M52mS are i100%

austeniic and contain no dela FN may be acceptable based on evaluation. [Same as Q-2000(d)j ferrite due to the high nickel composition (approximately 60%nickel.

Modification: If a flaw or evidence of a flaw is observed, in lieu of hydrostatic testing, a system leakage test and an ultrasonic examination (UT) of the weld Pressure Testing overlay will be performed consistent with ASME IWA-4540(a)(2), as modified (h) The completed repair shall be pressure tested in accordance with IWA-5000.

by Nonmandatory Appendix Q.

Basis: Application of IWA-4540(a)(2) for a system leakage test in lieu of a If the flaw penetrated the original pressure boundary prior to welding, or if any system hydrostatic test requires performance of NDE in accordance with the

.evidence of-a flaw penetrating the pressure boundary is observed during the sytmhdoaicetrqiesefrane[NEiacranewhth evidnceof flw peetrtin th prssur bonday i obsrve duingthe methods and acceptance criteria qf the applicable Subsection of the 1992 Edition welding operation, a system hydrostatic test shall be performed in accordance qfASME Section Ill. ASME Section III Sibsection SNb Article 50009 Edi with IWA-5000. If the system pressure boundary has not been penetrated, a Exain tion does not a e

ct ural weldiovela type confon system leakage, inservice, or functional test shall be performed in accordance Examination does not address the structyral weld overll type coowfiguration.

wit IA-500

-The NDE requirements of Nonmiandatory Appendix Q will/ be~fi)/ow~ied fo~r the with IWA-5000.

required NDE in lieu ofASME Section Ill. Code Case N-504-3 and Nonmandatory Appendix Q provide appropriate examinatiion requirements including examination volume, acceptance criteria, and examination methods per Appendix VllL Page 26 of 34

Request No. 09-ON-003 Enclosure I Table A2 Alternatives to Appendix VIII, Supplement 11 Appendix VIII of Section XI cannot be used for NDE of a structural weld overlay repair. Relief is requested to use the PDI program implementation of Appendix VIII. A detailed comparison of Appendix VIII and PDI requirements is summarized below.

Relief is requested to allow closer spacing of flaws provided the flaws do not interfere with detection or discrimination of other discontinuities. The specimens Used for qualification to the Tri-party (NRC/BWROG/EPRI) agreement have a flaw population density greater than allowed by current Code requirements. These samples have been used successfully for all previous qualifications under the Tri-party agreement program. To facilitate their use and provide continuity from the Tri-party agreement program to Supplement 11, the PDI program has merged the Tri-party test specimens into their structural weld overlay program.

SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING The Proposed Alternative to Supplement 11 Requirements WELDS 1 0 SPECIMEN REQUIREMENTS 1.1 General. The specimen set shall conform to the following requirements.

(b) The specimen set shall consist of at least three specimens having different nominal pipe diameters and overlay thicknesses. They shall include the minimlum and maximum Alternative: (b) The specimen set shall include specimens with overlays not thicker nominal pipe diameters for which the examination procedure is applicable. Pipe than 0.1 inch more than the minimurn thickness, nor thinner than 0.25 inch ofthe diameters within a range of 0.9 to 1.5 times a nominal diameter shall be considered C,

maximum nominal overlay thickness for which the examination procedure is equivalent. If the procedure is applicable to pipe diameters of 24 inch or larger, the aximorwio specimen set must include at least one specimen 24 inch or larger but need not include applicable.

the maximum diameter. The specimen set must include at least one specimen withthickness tolerance cotaine in the last sentence was reworded and the phrase "and the remainder shall he alternative flaws overlay thickness within -0.1 inch to +0.25 inch of the maximum nominal overlay was added to the next to last sentence in paragraph 1. 1 (d) (I).

thickness for which the procedure is applicable.

(d) Flaw Conditions Alternative: (1)... must be in or... intentional overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the base metal flaws.

(1) Base metal flaws. All flaws must be cracks in or near the butt weld heat-affected Specimens containing intergranular stress corrosion cracking shall be used when zone, open to the inside surface, and extending at least 75% through the base metal available. At least 70% of the flaws in the detection and siziig tests shall be cracks and wall. Flaws may extend 100% through the base metal and into the overlay material; in I

the remainder shall be alternative flaws. Alternative flaw mechanisms, if used, shall this case, intentional overlay fabrication flaws shall not interfere with ultrasonic provide crack-like reflective characteristics and shall be limited by the following:

detection or characterization of the cracking. Specimens containing IGSCC shall be used when available.

(a) The use of alternative flaws shall be limited to when the implantation of cracks produces spurious reflectors that are uncharacteristic of actual fla'ws.

(b) Flaws shall be semi elliptical with a tip width of less than or equal to 0.002 inches.

Page 27 of 34

Request No. 09-ON-003 Enclosure I Table A2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING WELDS PDI PROGRAM:

The Proposed Alternative to Supplement 11 Requirements I

Basis: This paragraph requires that all base metal/flaws be cracks. Implanting a crack requires excavation of the base material on at least one side o/theflaw. While this may be satisfactory for ferritic materials, it does not produce a useable axialflaw in austenitic materials because the sound beam, which normally passes only through base material, must now travel through weld material on at least one side, producing an unrealistic/flaw response. To resolve this issue, the PDI prograin revised this paragraph to allow use of alternativeflaw mechanisms under controlled conditions.

For example, ahernative flaws shall be limited to when implantation of cracks precludes obtaining an effective ultrasonic response, flaws shall be semni elliptical with a tip width qf less than or equal to 0.002 inches, and at least 70% ofiheflaws in the detection and sizing test shall be cracks and the remainder shall be alternative/laws.

To avoid confusion, the overlay thickness tolerance contained in paragraph 1. l(b) last sentence, was reworded and the phrase "and the remainder shall be alternaive flaws" was added to the next to last sentence. Paragraph 1. l (d))(1) includes the statemnent that intentional overlayfabricationflaws shall not interere with ultrasonic detection or characterization of the base inetal/laws.

(e) Detection Specimens (I) At least 20% but less than 40% of the flaws shall be oriented within +/-20' of the pipe axial direction. The remainder shall be oriented circumferentially. Flaws shall not be open to any surface to which the candidate has physical or visual access. The rules of IWA-3300 shall be used to determine whether closely spaced flaws should be treated as single or multiple flaws.

Alternative: (I) At least 20% but less than 40% of the base metal flaws shall be oriented within +/-20' of the pipe axial direction., The remainder shall be oriented circumferentially. Flaws shall not be open to any surface to which the candidate has physical or visual access.

Basis: The require/nent for axially oriented overlay faibricat ion.flaw's was excluded from the PDI Program as an improbable scenario. Weld overlays are m'jpicallv applied using aultomated GTA W techniques with thefiller metal applied in a circumferentiad direction. Because resultant fabrication induced discontinuities would also be expected to have major dimensions oriented in the circumferential direction axial overlciv fabrication flaws are unrealistic. The requirement/br using IWA-3300/or proximity flaw evaluation was excluded; instead indications will be sized based on their individual merits.

+

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

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

Basis: Inclusion qf "metal" and 'fabrication" provides clacriication. Flacw identification is improved by ensuring/laws are not masked by otherflaws.

Page 28 of 34

Request No. 09-ON-003 Enclosure I Table A2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING The Proposed Alternative to Supplement 11 Requirements WELDS Alternative: (a)(1) A base metal grading unit includes the overlay material and the outer 25% of the original overlaid weld. The base metal grading unit shall extend circumferentially for at least 1 inch and shall start at the weld centerline and be wide enough in the axial direction to encompass one half of the original weld crown and a (a)(1) A base grading unit shall include at least 3 inch of the length of the overlaid minimum of 0.50" of the adjacent base material.

weld. The base grading unit includes the outer 25% of the overlaid weld and base metal Basis: The phrase "and base metal on both sides, " was inadvertently included in the on both sides. The base grading unit shall not include the inner 75% of the overlaid description of a base inetalgrading unit, The PDl program intentionally excludes this weld and base metal overlay material, or base metal to-overlay interface.

requirement because some qf the qualification samples includeflaws on both sides of the weld. To avoid confusion several instances of the term -cracks" or "cracking" were changed to the term "flaws" because of the use f/alternative Flawi; mechanisms.

Modified to require that a base metal grading unit include at least I inch of the length of the overlaid weld, rather than 3 inches.

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

unit shall include the overlay metal within I inch of the crack location. This portion of Basis: Substituted terms provide clarification and are consistent with I. ld(l) above.

the overlay material shall not be used as part of any overlay grading unit.

The PD! program adjusts for this conservative change /br excluding this type gIading unit.

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

overlaid weld and base metal shall exist on either side of the base grading unit. The Basis: Modified to require sufficient un/lawed overlaid weld and base metal to exist on segment of weld length used in one base grading unit shall not be used in another base all sides of the grading unit to preclude inter/ering re/lections fom adiacent/laws, grading unit. Base grading units need not be uniformly spaced around the specimen.

rather than the 1 inch requirement.

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

Basis: The PD! program reduces the base metal-to-overlay inter/ace to at least 1 inch (b)(l) An overlay grading unit shall include the overlay material and the base metal-to-(in lieu of a minimum of 2 inches) and eliminates the minimum rectangular dimension.

overlay interface of at least 6 in2. The overlay grading unit shall be rectangular, with This criterion is necessary to allow use of existing examination specimens that were

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

Page 29 of 34

Request No. 09-ON-003 Table A2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING WELDS PDI PROGRAM:

The Proposed Alternative to Supplement 11 Requirements Alternative: (b)(2) Overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least I inch at both ends. Sufficient unflawed overlaid weld and base metal shall (b)(2) An overlay grading unit designed to be unflawed shall be surrounded by exist on both sides of the overlay fabrication grading unit to preclude interfering unflawed overlay material and unflawed base metal-to-overlay interface for at least I reflections from adjacent flaws. The specific area used in one overlay fabrication inch around its entire perimeter. The specific area used in one overlay grading unit grading unit shall not be used in another overlay fabrication grading unit. Overlay shall not be used in another overlay grading unit. Overlay grading units need not be fabrication grading units need not be spaced uniformly about the specimen.

spaced uniformly about the specimen.

Basis: Paragraph /. I (e)(2)(b)(2) states that overlay fibrication grading units designed to be unflawed shall be separated by un/lawed overlay material and un/flawed base inetal-to-overlay inte/face/for at least I inch at both ends, rather than aroind its entire perimeter.

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

of essential variables, at least one personnel qualification set is required.

Basis: Clarified the guidance for initial procedure qualifications versus quali.viing new values af essential variables.

(f) Sizing Specimen Alternative: (1) The...least 40% of the flaws shall be open to the inside surface. Sizing sets shall contain a distribution of flaw dimensions to assess sizing capabilities. For (1) The minimum number of flaws shall be ten. At. least 3 0% of the flaws shall be overlay fabrication flaws. At least 40% of the flaws shall be cracks open to the inside initial procedure qualification, sizing sets shall include the equivalent of three surface.

personnel qualification sets. To qualify new values of essential variables, at least one personnel qualification set is required.

Basis: Clarified the guidance for initial procedure qiualifications versus c/ual/iying new values of essential variables and is consistent with I. l d(l) above.

Alternative: (3) Base metal flaws used... circumferentially.

(3) Base metal cracking used for length sizing demonstrations shall be orientedB circumferentially.

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

(4) Depth sizing specimen sets shall include at least two distinct locations where Alternative: (4) Depth sizing specimen sets shall include at least two distinct locations cracking in the base metal extends into the overlay material by at least 0.1 inch in the where a base metal flaw extends into the overlay material by at least 0. 1 inch in the through-wall direction.

through-wall direction.

Basis: Clarified wording to be consistent with 1. ld(/) above.

Page 30 of 34

Request No. 09-ON-003 Enclosure I Table A2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIING The Proposed Alternative to Supplement 11 Requirements WELDS 2.0 Conduct of Performance Demonstration The specimen inside surface and identification shall be concealed from the candidate.

Alternative: The specimen prohibited. The overlay fabrication flaw test and the base All examninations shall be completed prior to grading the results and presenting the results to the candidate. Divulgence of particular specimen results or candidate viewing of unmasked specimens after the performance demonstration is prohibited.

Basis: Clar~fed wording to describe process.

2.1 Detection Test.

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

made aware of the type or types of grading units (base or overlay) that are present for Basis: Clarified wording simnilar to 1. I(e)2 above..

each specimen.

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

of the flaw that is in the outer 25% of the base wall thickness.

Basis: Clarified wording.for consistency.

2.3 Depth Sizing Test.

Alternative: (a) The depth sizing test may be conducted separately or in conjunction with the detection test.

(b) When the depth sizing test is conducted in conjunction with the detection test and For the depth sizing test, 80% of the flaws shall be sized at a specific location on the the detected flaws do not satisfy the requirements of 1. 1(f), additional specimens shall surface ofpthe specimeng ientifid tof the clandidhatbe. Ford athe remascining flocaw the rbe provided to the candidate. The regions containing a flaw to be sized shall beb surface of the specimen identified to the candidate. For the remaining flaws, the regions Ithe of each specimen containing a flaw to be sized shall be identified to the candidate.. The flaw in each region.

candidate shall determine the maximum depth of the flaw in each region.

(c) For a separate depth sizing test, the regions of each specimen containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.

Basis: Clarified wording to better describe process.

3.0 ACCEPTANCE CRITERIA 3.1 Detection Acceptance Criteria t pAlternative:

Examination procedures are qualified for detection when:

Examination procedures, equipment, and personnel are qualified for detection when the results of the performance demonstration satisfy the

a. All flaws within the scope of the procedure are detected and the results of the performance demonstration satisfy tlhe acceptance criteria of Table VI II-S2-I for false acceptance criteria of Table VIII-S2-1 for both detection and false calls. The criteria calls.

shall be satisfied separately by the demonstration results for base grading units and for

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

acceptance criteria defined in (c).

c. Examination equipment and personnel are qualified for detection when the results of Page 31 of 34

Request No. 09-ON-003 Enclosure I Table A2 Alternatives to Appendix VIIi, Supplement II SUPPLEMENT 1 - QUALIFICATION REQUIREMENTS FOR FULL PDI PROGRAM:

STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING WELDS The Proposed Alternative to Supplement 11 Requirements the performance demonstration satisfy the acceptance criteria of Table VIII-S2-I for both detection and false calls.

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

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

3.2 Sizing Acceptance Criteria (a) The RMS error of the flaw length measurements, as compared to the true flaw lengths, is less than or equal to 0.75 inch. The length of base metal cracking is B

asis :

C arifie wdg be consis witi.

Z:'

IBasis:

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

measured at the 75% through-base-metal position.

Alternative: This requirement is omitted.

(b) Al I extensions of base metal cracking into the overlay material by at least 0. 1 inch Basis: The requirement for reporting all extensions of cracking into the overlay is abe Allpextenasbeions oftbaseimetal k into the overlay material.

bomitted firom the PDI Program because it is redundant to the RMS colcuiations are reported as being intrusions into the overlay material.

performed in paragraph 3.2(c) and its presence adds confiusion and ambiguity to depth sizing as required by paragraph 3.2(c). This also makes the weld overlay program consistent with the supplement 2 depth sizing criteria.

Page 32 of 34

Request No. 09-ON-003 Enclosure I Table A3 Modifications to Code Case N-638-1 Code Case N-638-1 Modification/Basis Modification: The maximum area of an individual weld based on the finished surface over the ferritic material will not exceed 700 square Weld Area inches, and the depth of the WOL shall not be greater than one-half of 1.0(a) The maximum area of an individual weld the ferritic base metal thickness based on the finished surface shall be 100 sq. inch, Basis: The maximum area of the WOL for the RCP suction/discharge and the depth of the weld shall not be greater than line will be approximately 700 square inches over the ferritic material.

one-half of the ferritic base metal thickness.

Justification for extending the area limitation to 700 square inches is based on the overall conclusions of EPRI Report NP-10 1898 as discussed in Section 5. 0 of this Relief Request:

Modification: The required liquid penetrant examination of 4.0(b)will Examination be performed. In lieu of ultrasonic examination in accordance with (Referenced below in 4.0(b) para. 1.0(d) Prior to welding the area to be Appendix I, the ultrasonic examination will be in accordance with welded and a band around the area of at least 11/2 times the ASME Section XI, Code Case N-504-3 and Nonmandatory Appendix component thickness or 5 inch, whichever is less shall be at least Q.

50 0F.)

Basis: For the application of the weld overlay repair addressed in this request the appropriate examination methodologies and volumes are 4.0(b) The final weld surface and a band around the area defined in provided in Code Case N-504-3 and Nonmandatory Appendix Q Code para. 1.0 (d) shall be examined using a surface and ultrasonic methods Case N-638-1 applies to any type of welding where a temper bead when the completed weld has been at ambient temperature for at least technique is to be employed and is not specifically written for a weld 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The ultrasonic examination shall be in accordance with overlay repair. Code Case N-638-3 has eliminated the requirement to Appendix [.3 examine a band around the area to be welded, and specifies required post weld nondestructive examination of the welded region only. EPRI research has shown that it is not necessary to wait until ambient Refer to the 1989 Edition with the 1989 Addenda and later Editions temperature is reached before initiating the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold in order to and Addenda assure adequate hydrogen removal. No further tempering or potential hydrogen absorption effects will occur after deposition of the third overlay layer. See text for reference.

Page 33 of 34

Request No. 09-ON-003 Enclosure I Table A3 Modifications to Code Case N-638-1 Code Case N-638-1 Modification/Basis Modification: Preheat and interpass temperatures for the weld overlay will be measured using a contact pyrometer. Interpass temperature will be monitored for the first three layers at each repair location. The interpass temperature measurements will be taken every three to five passes. After the first three layers, interpass temperature measurements will be taken every six to ten passes for the subsequent layers. The heat input from layers beyond the third layer will not have a 4.0(c) requires temperature monitoring by welded thermocouples per metallurgical affect on the low alloy steel HAZ.

IWA-4610(a)

Basis: The proposed technique is faster and does not compromise collection of required data, so welded thermocouples are not planned for use to monitor interpass temperature during welding. Code Case N-638-3 has clarified this requirement and specifically allows use of pyrometer measurements to determine interpass temperatures. As noted earlier in this document, the NRC has previously approved this type of temperature data collection.

Page 34 of 34