ML061180496

Third 10-Year Inservice Inspection Interval, Relief Request I3R-08, Structural Weld Overlays on Pressurizer Spray, Relief, Safety and Surge Nozzle Safe-ends and Associated Alternative Repair Techniques

ML061180496
Person / Time
Site:	Byron
Issue date:	04/28/2006
From:	Hoots D M Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
1.10.0101, Byron 2006-0050
Download: ML061180496 (31)

Text

Ee~n.10 CFR 50.55a April 28, 2006 LTR: Byron 2006-0050 File: 1.10.0101 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos.NPF-37 and NPF-66 NRC Docket Nos.SIN 50-454 and STN 50-455

Subject:

Third 10-Year Inservice Inspection Interval, Relief Request 13R-08, Structural Weld Overlays on Pressurizer Spray, Relief, Safety and Surge Nozzle Safe-ends and Associated Alternative Repair Techniques Pursuant to 10 CFR 50.55a(a)(3)(i), Exelon Generation Company, LLC (EGC), is proposing an alternative to the repair/replacement requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section Xl, 2001 Edition, through 2003 Addenda, IWA-4000, for the structural weld overlays on pressurizer spray, relief, safety and surge nozzle safe-ends.

During the next Byron Station Unit 1 refueling outage (B1R14)and Byron Station Unit 2 refueling outage (B2R13), EGC will be performing full structural weld overlays (SWOLs)on all pressurizer nozzle safe-end to nozzle welds where Alloy 182 was originally used to butter the nozzle face and used to weld the stainless steel safe-ends to nozzles.The alternative is proposed under the provisions of 10 CFR 50.55a(a)(3)(i), an alternative that provides an acceptable level of quality and safety.EGO requests that the review of this relief request be completed by September 11, 2006.If you have any questions regarding this letter, please contact William Grundmann at (815)406-2800.Respectfully, David M.Hoots Site Vice President Byron Nuclear Generating Station DMH/JL/rah

Enclosure:

Byron Station Relief Request l3R-08 IS!Program Plan Units I&2, Third Intenial 10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 Page 1 of 30 Request for Relief for Alternative Requirements of Structural Weld Overlays (SWOLs)of the Pressurizer Surge, Spray, Safety and Relief Nozzles, Dissimilar Welds including the SWOLs of the Safe-End to Pipe, Reducer and Elbow Welds on Pressurizer Surge, Spray, Safety and Relief Nozzles In Accordance with 10 CFR 50.55a(a)(3)(i) 1.0 ASME CODE COMPONENT(S)

AFFECTED Code Class: 1

Reference:

IWA-4000,"Repair/Replacement Activities" Examination Category: R-A Item Number: See Table 1 for listing

Description:

Alternative Structural Weld Overlays (SWOL5)of the Pressurizer Surge, Spray, Safety and Relief Nozzles, Dissimilar Welds and also including the SWOLs of the Safe-End to Pipe, Reducer and Elbow Welds on Pressurizer Surge, Spray, Safety and Relief Nozzles Component Number(s):

See Table 1 for listing Drawing Number(s):

Unit 1: 1PZR-1-lSl (Pressurizer), 1RC-1-lSl SheetS (Surge Line), 1RC-l-ISI Sheet 16 (Spray Line), 1RC-1-lSl Sheet 32 (Relief Lines), and 1RC-1-lSl Sheet 35 (Safety Line)Unit 2: 2PZR-1-ISI (Pressurizer), 2RC-1-lSl Sheet 5 (Surge Line), 2RC-1-lSl Sheet 16 (Spray Line), 2RC-l-ISI Sheet 32 (Relief Lines), and 2RC-1-lSl Sheet 35 (Safety Line)2.0 APPLICABLE CODE EDITION AND ADDENDA The Inservice Inspection program is based on the American Society of Mechanical Engineers (ASME)Boiler and Pressure Vessel (B&PV)Code, Section Xl, 2001 Edition through the 2003 Addenda.3.0 APPLICABLE CODE REQUIREMENT ASME Section Xl, 2001 Edition, through 2003 Addenda, IWA-4000 requires that repairs be performed in accordance with the owner's original construction Code of the component or system, or later editions and addenda of the Code.The pressurizer Code of Construction is ASME Section III, 1971 Edition through Summer 1973 Addenda, with Code Case NB-4643, 1493-1.The proposed alternative activities are supported by the requirements presented in: ASME Code Case N-638-1"Similar and Dissimilar Metal Welding Using Ambient Temperature Machine ClAW Temper Bead Technique" conditionally approved in Exe/on-Byron Station IS!Program Plan____________

____________________

Unitsl&?~Third In ten/al 10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 2 of 30)Nuclear Regulatory Commission (NRC)Regulatory Guide (RG)1.147 Revision 14.ASME Code Case N-504-2"Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping"conditionally approved in RG 1.147 Revision 14.In addition, ASME Code, Section Xl, 1995 Edition including Addenda through 1996, Appendix VIII Supplement 11 is used for examination qualification requirements of the final welded overlays.4.0 REASON FOR THE REQUEST Dissimilar metal welds (DMWs), typically consisting of Alloy 182 weld are frequently used in pressurized water reactors (PWR)construction to connect stainless steel pipe and safe ends to vessel nozzles, generally constructed of carbon or low alloy ferritic steel.These welds have shown a propensity for primary water stress corrosion cracking (PWSCC)degradation, especially in components subjected to higher operating temperatures, such as the pressurizer (PZR).Exelon Generating Company, LLC (EGO), Byron Station Units 1 and 2 is proposing to take a proactive approach on the Byron Station Unit 1 and 2 Pressurizer and apply a preemptive Structural Weld Overlay (SWOL)on the Pressurizer Nozzle Safe-end to Nozzle Dissimilar Metal Welds to mitigate the occurrence of PWSCC prior to detectable evidence of PWSCC.Structural Weld Overlays (SWOL)have been used for several years on both boiling water reactors (BWR)and pressurized water reactors (PWR)to arrest existing flaws from propagating while establishing a new structural pressure boundary.In some cases, SWOLs have been used to reestablish structural integrity of the DMW containing through wall leaking flaws.The SWOLs will also facilitate ultrasonic examination of the DMWs by providing a more consistent outer surface configuration from which scanning can be performed.

The welding will be performed using a remote mechanized Gas Tungsten-Arc Welding (GTAW)process and using the ambient temperature temper bead method with AWS Classification ERNiCrFe-7 (Alloy 52 or Alloy 52M*)weld metal.Manual GTAW, using Alloy 52 or Alloy 52M, will only be permitted subsequent to the SWOLs being essentially completed or to repair indications detected in base materials prior to overlay initiation.

Also, Manual GTAW may be used if local repairs of weld defects are necessary or additional weld metal is required locally to form the final SWOL contour.Shielded Metal Arc Welds (SMAW), using AWS Classification ERNiCrFe-7 (Alloy 152), will be used only as needed to repair indications in base materials prior to overlay initiation.

• The material supplier's weld wire designation may be either 52M or 52MS.The"S"designates the process route that converts the hot-rolled billet into finished cold-drawn wire.The material properties are not Exe/on-Byron Station IS!Program Plan________________

Units 1&2, Third Interval 10 CFR 50.55a RELIEF REQUEST l3R-08 Revision 0 (Page 3 of 30)affected.For this reason, references herein to 52M are considered to encompass S2MS filler material as well.As discussed herein, there is no comprehensive criterion for a licensee to apply a SWOL repair to a DMW that is constructed of Alloy 82/182 weld material and is believed to be susceptible to or contain PWSCC degradation.

Although the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section Xl, 2001 Edition, through 2003 Addenda, IWA-4000, is used for the Byron Unit 1 and 2 Section Xl Repair/Replacement Program, it does not contain the needed requirements for this type of weld overlay repair.Repair/replacement activities associated with weld overlays of this type are required to address the materials, welding parameters, personnel radiation exposure concerns, operational constraints, examination techniques and procedure requirements.

5.0 PROPOSED

ALTERNATIVE AND BASIS FOR USE EGO proposes using SWOL's designed in accordance with Code Cases N-504-2 (Reference 1)with the modifications proposed in Table 2.Code Case N-504-2, currently approved for use in RG 1.147 with additional requirements of ASME Section Xl, 2005 Addenda Appendix Q being required, allows a flaw to be reduced to an acceptable size by deposition of weld reinforcement on the outside surface of the pipe without flaw removal.The SWOL's will extend around the full circumference of the applicable DMWs as required by Code Case N-504-2.The specific thickness and length will be determined according to the guidance provided in Code Case N-504-2, The overlay will completely cover the DMWs and the adjacent stainless steel safe-end to pipe welds with Alloy 52 or Alloy 52M material that is highly resistant to PWSCC.A typical SWOL configuration is shown in Figure 1.The temper bead welding technique for the specified nozzles adjacent to DMWs will be implemented in accordance with ASME Code Case N-638-1 (Reference 2)with the modifications proposed in Table 3.The ultrasonic examination (UT)of the completed SWOL will be accomplished in accordance with ASME Section Xl, 1995 Edition with the 1996 Addenda, Appendix VIII Supplement 11 with the modifications described in Table 4.These modifications were developed by the EPRI Performance Demonstration Initiative (PDI)program to implement the requirements of Appendix VIII.These EPRI Supplement 11 modifications have previously been approved for use (see Reference 6).6.0 DURATION OF THE PROPOSED ALTERNATIVE This relief request will be implemented during the remainder of Byron Station, Units 1 and 2 third ten-year inservice inspection interval.Exe Ion-Byron Station IS!Program Plan_______________Units 1&2, Third Interval 10 CFR 50.55a RELIEF REQUEST l3R-08 Revision 0 (Page 4 of 30)7.0 PRECEDENT Similar relief requests have been previously approved for AmerGen Energy Company for its Three Mile Island Nuclear Station, Unit 1 in July, 2004, at Constellation Energy's Calvert Cliffs Nuclear Power Plant, Unit 2 in July, 2005 and at Dominion Nuclear Connecticut's Millstone Power Station Unit 3 in October 2005.These requests were associated with welding over detected flaws outside the acceptance criteria of Section Xl.

8.0 REFERENCES

1.ASME Code Case N-504-2,"Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping,"dated March 12, 1997.2.ASME Code Case N-638-1,"Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,"

dated February 13, 2003.3.Letter from Richard Laufer, NRC to Christopher M.Crane, AmerGen,"Three Mile Island Nuclear Station, Unit 1 (TMI-1)Request for Relief From Flaw, Heat Treatment, and Nondestructive Examination Requirements for the Third 10 year lnservice Inspection (ISI)Interval (TAC No.MC1O1),"Accession Number ML041670510, dated July 21, 2004.4.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 (TAO Nos.MC6219 and MC6220),"Accession Number ML051930316, dated July 20, 2005.5.Letter from L.Raghavan, NRC to Mano K.Nazar, l&M,"Donald C.Cook Nuclear Plant, Unit 1 (DOCNP-1)-Alternatives Regarding Repair of Weld 1-PZR-23 on Pressurizer Nozzle to Valve Inlet Line (TAO No.MC6704),"Accession Number ML053220019, dated December 1, 2005.6.Letter from L.Raghavan, NRC, to Mano K.Nazar, l&M,"Donald C.Cook Nuclear Plant, Unit 1-Alternative to Repair Requirements of Section Xl of the American Society of Mechanical Engineers Code (TAC No.MC06751),"

Accession Number ML051720006, dated June 27, 2005.7.Letter from Leslie N.Hartz, Dominion Nuclear Connecticut, to NRC Document Control Desk,"Dominion Nuclear Connecticut, Inc., Millstone Power Station Unit 3, Second 10-year Inservice Inspection Interval, Revision 1 to Relief Request IR-2-39, Use of Weld overlay and Associated Alternative Repair Techniques,"

Accession Number ML052930108, dated October 19, 2005.8.Letter from Richard J.Laufer, NRC, to Bryce L.Shriver, PPL Susquehanna,"Susquehanna Steam Electric Station, Unit 1-Relief from American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code), Section Xl Appendix VIII, Supplement 11, Requirements and Oases N-504-2 and N-638 Exe/on-Byron Station IS!Program Plan______Unitsl&2, Third_Interval 10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 5 of 30)Requirements (TAO Nos.MC2450 and MC2594),"Accession Number ML051220568, dated June 22, 2005.9.0 ATTACHMENTS 1.RRA 05-08, BCO6-134, Technical Basis Paper N-638-x, Ambient Temperature Temperbead Welding: Begin 48 Hour Hold After 3~Layer Completion, authored by Bruce Newton, PCI Energy Services.2.RRM-02-05, BCO4-1 003, Develop New Code Case to Address Inconel Weld Overlay on Various Materials, SIR-05-030, Rev.0, Effect of Chromium Content on Nickel-base Alloy SOC Resistance Exelon-Byron Station IS!Program Plan________________

10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 6 of 30)TABLE I COMPONENT IDENTIFICATION Unitsl&2, Third Intenial For Unit I Pressurizer IRYOIS SAFE-END IDENTIFICATION ITEM#SIZE PIPING WELD (Line,_Weld)

CONFIGURATION ITEM#Surge PN-01 Fl R1.11 R1.15 14"1RY11AA-14", J1A Safe-end to Pipe R1.11 Spray Relief PN-02 F2 R1.11 R1.15 4"1RYO1C-4", J1 6"x4"Reducerto Safe-end R1.11 PN-03 F3 R1.15 6"IRYO2A-6", J1 Safe-end to Out 45°Elbow R1.20 Safety A Safety B PN-04 F4 R1.1S 6"1RYO3AA-6", J1 Safe-end to Cut 90°Elbow R1.20 PN-05 ES R1.15 6"1RYO3AB-6", J1 Safe-end to Cut 90°Elbow R1.20 Safety C PN-06 E6 R1.15 6"1RYO3AC-6", J1 Safe-end to Cut 90°Elbow R1.20 For Unit 2 Pressurizer 2RYOIS SAFE-END IDENTIFICATION ITEM#SIZE PIPING WELD (Line,_Weld)

CONFIGURATION ITEM#Surge PN-01 El Rl.11 R1.15 14"2RY11AA-l4", J1 Safe-endto Pipe R1.1l Spray PN-02 E2 R1.1l Rl.15 4"2RYO1C-4", Jl 6"x4"Reducer to Safe-end Rl.ll Relief PN-03 E3 Rl.lS 6"2RYO2A-6", J1 Safe-end to Cut 45°Elbow Rl.20 Safety A PN-04 E4 Rl.15 6"2RYO3AA-6", J1 Safe-end to Cut 90°Elbow Rl.20 Safety B PN-05 ES R1.l5 6"2RYO3AB-6", Jl Safe-end to Cut 90°Elbow Rl.20 Safety 0 PN-06 E6 R1.15 6"2RYO3AC-6", Jl Safe-end to Cut 90°R1.20 Elbow Note: Item numbers reflect Risk-Informed classification per ASME Code Case N-578-1.Ri.ii: Elements Subject to Thermal Fatigue.Ri.iS: Elements Subject to Primary Water Stress Corrosion Cracking.Ri20: Elements not Subject to a Damage Mechanism.

Exelon-Byron Station ISI Program Plan Units I&2, Third Interval 10 CFR 50.55a RELIEF REQUEST I3R-08 Revision 0 (Page 7 of 30)Figure 1 Typical SWOL Configuration SS Eli SWOL (A52~(SA-182 F316L);EJNozzle Weld Class 2)Exelon-Byron Station IS!Program Plan Units 1&2, Third Interval IOCFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 8 of 30)TABLE 2 DESIGN I MATERIAL I NONDESTRUCTIVE EXAMINATION Modifications to Code Case N-504-2 and ASME Section Xl, Appendix Q CODE CASE N-504-2 AND ASME SECTION XI APPENDIX Q Reply: It is the opinion of the Committee that, Modification:

Oode Oase N-504-2 and Appendix in lieu of the requirements of IWA-4120 in Q will be used for the weld overlay of the ferritic Editions and Addenda up to and including the (P3)nozzle material, nickel alloy (F43/P43)1989 Edition with the 1990 Addenda, in IWA-weld material, and austenitic stainless steel 4170(b)in the 1989 Edition with the 1991 base (P8, safe end and pipe)and weld Addenda up to and including the 1995 Edition, materials.

and in IWA-4410 in the 1995 Edition with the 1995 Addenda and later Editions and Addenda, defect in austenitic stainless steel piping may be reduced to a flaw of acceptable size in accordance with IWB-3640 from the Basis: Oode Oase N-504-2 is accepted for use in the current NRC Regulatory Guide 1.147 Rev.14, and has been used extensively in BWR primary system piping.More recently, N-504-2 has been applied to PWR applications, 1983 Edition with the Winter 1985 Addenda, or later Editions and Addenda, by deposition of with modifications, for the weld overlay repair of dissimilar metal welds with known flaws.weld reinforcement (weld overlay)on the Industry operating experience in the area has outside surface of the pipe, provided the following requirements are met.shown that PWSOO in Alloy 82/182 will arrest at the interface with stainless steel base metal, ferritic base metal, or Alloy 52/52M/1 52 weld metal.The 360°full structural weld overlay will control growth in any PWSCC crack and maintain weld integrity.

The weld overlay will also induce compressive stress in the weld, thus potentially impeding growth of any reasonably shallow cracks.Furthermore, the overlay will be sized to meet all structural requirements without considering the existing 82/1 82 weld.Exe/on-Byron Station Ee~n.10 CFR 50.55a April 28, 2006 LTR: Byron 2006-0050 File: 1.10.0101 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos.NPF-37 and NPF-66 NRC Docket Nos.SIN 50-454 and STN 50-455

Subject:

Third 10-Year Inservice Inspection Interval, Relief Request 13R-08, Structural Weld Overlays on Pressurizer Spray, Relief, Safety and Surge Nozzle Safe-ends and Associated Alternative Repair Techniques Pursuant to 10 CFR 50.55a(a)(3)(i), Exelon Generation Company, LLC (EGC), is proposing an alternative to the repair/replacement requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section Xl, 2001 Edition, through 2003 Addenda, IWA-4000, for the structural weld overlays on pressurizer spray, relief, safety and surge nozzle safe-ends.

During the next Byron Station Unit 1 refueling outage (B1R14)and Byron Station Unit 2 refueling outage (B2R13), EGC will be performing full structural weld overlays (SWOLs)on all pressurizer nozzle safe-end to nozzle welds where Alloy 182 was originally used to butter the nozzle face and used to weld the stainless steel safe-ends to nozzles.The alternative is proposed under the provisions of 10 CFR 50.55a(a)(3)(i), an alternative that provides an acceptable level of quality and safety.EGO requests that the review of this relief request be completed by September 11, 2006.If you have any questions regarding this letter, please contact William Grundmann at (815)406-2800.Respectfully, David M.Hoots Site Vice President Byron Nuclear Generating Station DMH/JL/rah

Enclosure:

Byron Station Relief Request l3R-08 IS!Program Plan Units I&2, Third Intenial 10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 Page 1 of 30 Request for Relief for Alternative Requirements of Structural Weld Overlays (SWOLs)of the Pressurizer Surge, Spray, Safety and Relief Nozzles, Dissimilar Welds including the SWOLs of the Safe-End to Pipe, Reducer and Elbow Welds on Pressurizer Surge, Spray, Safety and Relief Nozzles In Accordance with 10 CFR 50.55a(a)(3)(i) 1.0 ASME CODE COMPONENT(S)

AFFECTED Code Class: 1

Reference:

IWA-4000,"Repair/Replacement Activities" Examination Category: R-A Item Number: See Table 1 for listing

Description:

Alternative Structural Weld Overlays (SWOL5)of the Pressurizer Surge, Spray, Safety and Relief Nozzles, Dissimilar Welds and also including the SWOLs of the Safe-End to Pipe, Reducer and Elbow Welds on Pressurizer Surge, Spray, Safety and Relief Nozzles Component Number(s):

See Table 1 for listing Drawing Number(s):

Unit 1: 1PZR-1-lSl (Pressurizer), 1RC-1-lSl SheetS (Surge Line), 1RC-l-ISI Sheet 16 (Spray Line), 1RC-1-lSl Sheet 32 (Relief Lines), and 1RC-1-lSl Sheet 35 (Safety Line)Unit 2: 2PZR-1-ISI (Pressurizer), 2RC-1-lSl Sheet 5 (Surge Line), 2RC-1-lSl Sheet 16 (Spray Line), 2RC-l-ISI Sheet 32 (Relief Lines), and 2RC-1-lSl Sheet 35 (Safety Line)2.0 APPLICABLE CODE EDITION AND ADDENDA The Inservice Inspection program is based on the American Society of Mechanical Engineers (ASME)Boiler and Pressure Vessel (B&PV)Code, Section Xl, 2001 Edition through the 2003 Addenda.3.0 APPLICABLE CODE REQUIREMENT ASME Section Xl, 2001 Edition, through 2003 Addenda, IWA-4000 requires that repairs be performed in accordance with the owner's original construction Code of the component or system, or later editions and addenda of the Code.The pressurizer Code of Construction is ASME Section III, 1971 Edition through Summer 1973 Addenda, with Code Case NB-4643, 1493-1.The proposed alternative activities are supported by the requirements presented in: ASME Code Case N-638-1"Similar and Dissimilar Metal Welding Using Ambient Temperature Machine ClAW Temper Bead Technique" conditionally approved in Exe/on-Byron Station IS!Program Plan____________

____________________

Unitsl&?~Third In ten/al 10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 2 of 30)Nuclear Regulatory Commission (NRC)Regulatory Guide (RG)1.147 Revision 14.ASME Code Case N-504-2"Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping"conditionally approved in RG 1.147 Revision 14.In addition, ASME Code, Section Xl, 1995 Edition including Addenda through 1996, Appendix VIII Supplement 11 is used for examination qualification requirements of the final welded overlays.4.0 REASON FOR THE REQUEST Dissimilar metal welds (DMWs), typically consisting of Alloy 182 weld are frequently used in pressurized water reactors (PWR)construction to connect stainless steel pipe and safe ends to vessel nozzles, generally constructed of carbon or low alloy ferritic steel.These welds have shown a propensity for primary water stress corrosion cracking (PWSCC)degradation, especially in components subjected to higher operating temperatures, such as the pressurizer (PZR).Exelon Generating Company, LLC (EGO), Byron Station Units 1 and 2 is proposing to take a proactive approach on the Byron Station Unit 1 and 2 Pressurizer and apply a preemptive Structural Weld Overlay (SWOL)on the Pressurizer Nozzle Safe-end to Nozzle Dissimilar Metal Welds to mitigate the occurrence of PWSCC prior to detectable evidence of PWSCC.Structural Weld Overlays (SWOL)have been used for several years on both boiling water reactors (BWR)and pressurized water reactors (PWR)to arrest existing flaws from propagating while establishing a new structural pressure boundary.In some cases, SWOLs have been used to reestablish structural integrity of the DMW containing through wall leaking flaws.The SWOLs will also facilitate ultrasonic examination of the DMWs by providing a more consistent outer surface configuration from which scanning can be performed.

The welding will be performed using a remote mechanized Gas Tungsten-Arc Welding (GTAW)process and using the ambient temperature temper bead method with AWS Classification ERNiCrFe-7 (Alloy 52 or Alloy 52M*)weld metal.Manual GTAW, using Alloy 52 or Alloy 52M, will only be permitted subsequent to the SWOLs being essentially completed or to repair indications detected in base materials prior to overlay initiation.

Also, Manual GTAW may be used if local repairs of weld defects are necessary or additional weld metal is required locally to form the final SWOL contour.Shielded Metal Arc Welds (SMAW), using AWS Classification ERNiCrFe-7 (Alloy 152), will be used only as needed to repair indications in base materials prior to overlay initiation.

• The material supplier's weld wire designation may be either 52M or 52MS.The"S"designates the process route that converts the hot-rolled billet into finished cold-drawn wire.The material properties are not Exe/on-Byron Station IS!Program Plan________________

Units 1&2, Third Interval 10 CFR 50.55a RELIEF REQUEST l3R-08 Revision 0 (Page 3 of 30)affected.For this reason, references herein to 52M are considered to encompass S2MS filler material as well.As discussed herein, there is no comprehensive criterion for a licensee to apply a SWOL repair to a DMW that is constructed of Alloy 82/182 weld material and is believed to be susceptible to or contain PWSCC degradation.

Although the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section Xl, 2001 Edition, through 2003 Addenda, IWA-4000, is used for the Byron Unit 1 and 2 Section Xl Repair/Replacement Program, it does not contain the needed requirements for this type of weld overlay repair.Repair/replacement activities associated with weld overlays of this type are required to address the materials, welding parameters, personnel radiation exposure concerns, operational constraints, examination techniques and procedure requirements.

5.0 PROPOSED

ALTERNATIVE AND BASIS FOR USE EGO proposes using SWOL's designed in accordance with Code Cases N-504-2 (Reference 1)with the modifications proposed in Table 2.Code Case N-504-2, currently approved for use in RG 1.147 with additional requirements of ASME Section Xl, 2005 Addenda Appendix Q being required, allows a flaw to be reduced to an acceptable size by deposition of weld reinforcement on the outside surface of the pipe without flaw removal.The SWOL's will extend around the full circumference of the applicable DMWs as required by Code Case N-504-2.The specific thickness and length will be determined according to the guidance provided in Code Case N-504-2, The overlay will completely cover the DMWs and the adjacent stainless steel safe-end to pipe welds with Alloy 52 or Alloy 52M material that is highly resistant to PWSCC.A typical SWOL configuration is shown in Figure 1.The temper bead welding technique for the specified nozzles adjacent to DMWs will be implemented in accordance with ASME Code Case N-638-1 (Reference 2)with the modifications proposed in Table 3.The ultrasonic examination (UT)of the completed SWOL will be accomplished in accordance with ASME Section Xl, 1995 Edition with the 1996 Addenda, Appendix VIII Supplement 11 with the modifications described in Table 4.These modifications were developed by the EPRI Performance Demonstration Initiative (PDI)program to implement the requirements of Appendix VIII.These EPRI Supplement 11 modifications have previously been approved for use (see Reference 6).6.0 DURATION OF THE PROPOSED ALTERNATIVE This relief request will be implemented during the remainder of Byron Station, Units 1 and 2 third ten-year inservice inspection interval.Exe Ion-Byron Station IS!Program Plan_______________Units 1&2, Third Interval 10 CFR 50.55a RELIEF REQUEST l3R-08 Revision 0 (Page 4 of 30)7.0 PRECEDENT Similar relief requests have been previously approved for AmerGen Energy Company for its Three Mile Island Nuclear Station, Unit 1 in July, 2004, at Constellation Energy's Calvert Cliffs Nuclear Power Plant, Unit 2 in July, 2005 and at Dominion Nuclear Connecticut's Millstone Power Station Unit 3 in October 2005.These requests were associated with welding over detected flaws outside the acceptance criteria of Section Xl.

8.0 REFERENCES

1.ASME Code Case N-504-2,"Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping,"dated March 12, 1997.2.ASME Code Case N-638-1,"Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,"

dated February 13, 2003.3.Letter from Richard Laufer, NRC to Christopher M.Crane, AmerGen,"Three Mile Island Nuclear Station, Unit 1 (TMI-1)Request for Relief From Flaw, Heat Treatment, and Nondestructive Examination Requirements for the Third 10 year lnservice Inspection (ISI)Interval (TAC No.MC1O1),"Accession Number ML041670510, dated July 21, 2004.4.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 (TAO Nos.MC6219 and MC6220),"Accession Number ML051930316, dated July 20, 2005.5.Letter from L.Raghavan, NRC to Mano K.Nazar, l&M,"Donald C.Cook Nuclear Plant, Unit 1 (DOCNP-1)-Alternatives Regarding Repair of Weld 1-PZR-23 on Pressurizer Nozzle to Valve Inlet Line (TAO No.MC6704),"Accession Number ML053220019, dated December 1, 2005.6.Letter from L.Raghavan, NRC, to Mano K.Nazar, l&M,"Donald C.Cook Nuclear Plant, Unit 1-Alternative to Repair Requirements of Section Xl of the American Society of Mechanical Engineers Code (TAC No.MC06751),"

Accession Number ML051720006, dated June 27, 2005.7.Letter from Leslie N.Hartz, Dominion Nuclear Connecticut, to NRC Document Control Desk,"Dominion Nuclear Connecticut, Inc., Millstone Power Station Unit 3, Second 10-year Inservice Inspection Interval, Revision 1 to Relief Request IR-2-39, Use of Weld overlay and Associated Alternative Repair Techniques,"

Accession Number ML052930108, dated October 19, 2005.8.Letter from Richard J.Laufer, NRC, to Bryce L.Shriver, PPL Susquehanna,"Susquehanna Steam Electric Station, Unit 1-Relief from American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code), Section Xl Appendix VIII, Supplement 11, Requirements and Oases N-504-2 and N-638 Exe/on-Byron Station IS!Program Plan______Unitsl&2, Third_Interval 10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 5 of 30)Requirements (TAO Nos.MC2450 and MC2594),"Accession Number ML051220568, dated June 22, 2005.9.0 ATTACHMENTS 1.RRA 05-08, BCO6-134, Technical Basis Paper N-638-x, Ambient Temperature Temperbead Welding: Begin 48 Hour Hold After 3~Layer Completion, authored by Bruce Newton, PCI Energy Services.2.RRM-02-05, BCO4-1 003, Develop New Code Case to Address Inconel Weld Overlay on Various Materials, SIR-05-030, Rev.0, Effect of Chromium Content on Nickel-base Alloy SOC Resistance Exelon-Byron Station IS!Program Plan________________

10 CFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 6 of 30)TABLE I COMPONENT IDENTIFICATION Unitsl&2, Third Intenial For Unit I Pressurizer IRYOIS SAFE-END IDENTIFICATION ITEM#SIZE PIPING WELD (Line,_Weld)

CONFIGURATION ITEM#Surge PN-01 Fl R1.11 R1.15 14"1RY11AA-14", J1A Safe-end to Pipe R1.11 Spray Relief PN-02 F2 R1.11 R1.15 4"1RYO1C-4", J1 6"x4"Reducerto Safe-end R1.11 PN-03 F3 R1.15 6"IRYO2A-6", J1 Safe-end to Out 45°Elbow R1.20 Safety A Safety B PN-04 F4 R1.1S 6"1RYO3AA-6", J1 Safe-end to Cut 90°Elbow R1.20 PN-05 ES R1.15 6"1RYO3AB-6", J1 Safe-end to Cut 90°Elbow R1.20 Safety C PN-06 E6 R1.15 6"1RYO3AC-6", J1 Safe-end to Cut 90°Elbow R1.20 For Unit 2 Pressurizer 2RYOIS SAFE-END IDENTIFICATION ITEM#SIZE PIPING WELD (Line,_Weld)

CONFIGURATION ITEM#Surge PN-01 El Rl.11 R1.15 14"2RY11AA-l4", J1 Safe-endto Pipe R1.1l Spray PN-02 E2 R1.1l Rl.15 4"2RYO1C-4", Jl 6"x4"Reducer to Safe-end Rl.ll Relief PN-03 E3 Rl.lS 6"2RYO2A-6", J1 Safe-end to Cut 45°Elbow Rl.20 Safety A PN-04 E4 Rl.15 6"2RYO3AA-6", J1 Safe-end to Cut 90°Elbow Rl.20 Safety B PN-05 ES R1.l5 6"2RYO3AB-6", Jl Safe-end to Cut 90°Elbow Rl.20 Safety 0 PN-06 E6 R1.15 6"2RYO3AC-6", Jl Safe-end to Cut 90°R1.20 Elbow Note: Item numbers reflect Risk-Informed classification per ASME Code Case N-578-1.Ri.ii: Elements Subject to Thermal Fatigue.Ri.iS: Elements Subject to Primary Water Stress Corrosion Cracking.Ri20: Elements not Subject to a Damage Mechanism.

Exelon-Byron Station ISI Program Plan Units I&2, Third Interval 10 CFR 50.55a RELIEF REQUEST I3R-08 Revision 0 (Page 7 of 30)Figure 1 Typical SWOL Configuration SS Eli SWOL (A52~(SA-182 F316L);EJNozzle Weld Class 2)Exelon-Byron Station IS!Program Plan Units 1&2, Third Interval IOCFR 50.55a RELIEF REQUEST 13R-08 Revision 0 (Page 8 of 30)TABLE 2 DESIGN I MATERIAL I NONDESTRUCTIVE EXAMINATION Modifications to Code Case N-504-2 and ASME Section Xl, Appendix Q CODE CASE N-504-2 AND ASME SECTION XI APPENDIX Q Reply: It is the opinion of the Committee that, Modification:

Oode Oase N-504-2 and Appendix in lieu of the requirements of IWA-4120 in Q will be used for the weld overlay of the ferritic Editions and Addenda up to and including the (P3)nozzle material, nickel alloy (F43/P43)1989 Edition with the 1990 Addenda, in IWA-weld material, and austenitic stainless steel 4170(b)in the 1989 Edition with the 1991 base (P8, safe end and pipe)and weld Addenda up to and including the 1995 Edition, materials.

and in IWA-4410 in the 1995 Edition with the 1995 Addenda and later Editions and Addenda, defect in austenitic stainless steel piping may be reduced to a flaw of acceptable size in accordance with IWB-3640 from the Basis: Oode Oase N-504-2 is accepted for use in the current NRC Regulatory Guide 1.147 Rev.14, and has been used extensively in BWR primary system piping.More recently, N-504-2 has been applied to PWR applications, 1983 Edition with the Winter 1985 Addenda, or later Editions and Addenda, by deposition of with modifications, for the weld overlay repair of dissimilar metal welds with known flaws.weld reinforcement (weld overlay)on the Industry operating experience in the area has outside surface of the pipe, provided the following requirements are met.shown that PWSOO in Alloy 82/182 will arrest at the interface with stainless steel base metal, ferritic base metal, or Alloy 52/52M/1 52 weld metal.The 360°full structural weld overlay will control growth in any PWSCC crack and maintain weld integrity.

The weld overlay will also induce compressive stress in the weld, thus potentially impeding growth of any reasonably shallow cracks.Furthermore, the overlay will be sized to meet all structural requirements without considering the existing 82/1 82 weld.Exe/on-Byron Station