NLS2010013, Request Relief from Certain Inservice Inspection (ISI) Code Requirements

Request Relief from Certain Inservice Inspection (ISI) Code Requirements

ML100480038
Person / Time
Site:	Cooper
Issue date:	02/05/2010
From:	O'Grady B Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NLS2010013
Download: ML100480038 (26)

Text

N Nebraska Public Power District "Always there when you need us" 10 CFR 50.55a NLS2010013 February 5, 2010 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

10 CFR 50.55a Request Number RI-36, Revision 0 Cooper Nuclear Station, Docket No. 50-298, DPR-46

Dear Sir or Madam:

The purpose of this letter is to request that the Nuclear Regulatory Commission (NRC) grant Nebraska Public Power District (NPPD) relief from certain inservice inspection (ISI) code requirements for Cooper Nuclear Station (CNS) pursuant to 10 CFR 50.55a.

10 CFR 50.55a Request Number RI-36, Revision 0 is applicable to the fourth ten-year ISI interval, which began March 1, 2006. NPPD requests NRC approval of the attached request by February 8, 2011, which represents a standard twelve-month review period following the submittal. Approval of this request is needed to support weld repair work, if needed, for Refueling Outage 26.

This request is very similar to RI-35, Revision 1, approved by the NRC in the Safety Evaluation provided August 15, 2008 for Refueling Outage 24.

RI-36, Revision 0 is contained in the attachment to this letter.

If you have any questions concerning this matter, please contact David Van Der Kamp, Licensing Manager, at (402) 825-2904.

Sincerely, Brian J. O'Grady Site Vice President

/dm COOPER NUCLEAR STATION P.0. Box 98 / Bro wnville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www nppd.com

NLS2010013 Page 2 of 2 Attachment cc: Regional Administrator w/ attachment USNRC - Region IV Cooper Project Manager w/ attachment USNRC - NRR Project Directorate IV- 1 Senior Resident Inspector w/ attachment USNRC - CNS NPG Distribution w/ attachment CNS Records w/ attachment

NLS2010013 Attachment Page 1 of 23 10CFR 50.55a Request NumberRI-36, Revision 0 Alternative Weld Overlay Repairs for Dissimilar. Metal Welds Joining Nozzle to Control Rod Drive End Cap Cooper Nuclear Station Docket No. 50-298, DPR-46 Proposed Alternative in Accordance to 10CFR50.55a(a)(3)(i)

--Alternative Provides Acceptable Level of Quality and Safety--

Applicable Code Components Affected Code Class: 1 Examination Categories: B-F Item Number: B5.10 Component Numbers: RCA-BF-1, 5 inch Control Rod Drive Return Cap to Nozzle N9 Weld

Applicable Code Edition and Addenda

American Society of Mechanical Engineers (ASME) Code Section XI, 2001 Edition, 2003 Addenda.

Applicable Code Requirement

IWA-4421 (a) and IWA-46 11.1 (a) require removal of the detected flaw.

IWA-4610(a) requires that the area to be welded shall be pre-heated to 300TF minimum for gas tungsten arc welding (GTAW).

IWA-4610(a) also requires the use of thermocouples to monitor process temperatures.

IWA-463 1(b) specifies the surface of the completed weld on the ferritic steel shall not exceed 100 square inches.

IWA-4633.2(c) specifies the first three layers of the weld shall be deposited with heat inputs within +/-10% of that used in the procedure qualification test. Subsequent layers shall be deposited using heat input equal to or less than that used for layers beyond the third in the procedure qualification.

IWA-4633.2(c) also specifies that at least one layer of weld reinforcement shall be deposited and then this reinforcement shall be removed, to be substantially flush with the surface surrounding the weld. -

NLS2010013 Attachment Page 2 of 23 Appendix VIII provides requirements for perf6rmance demonstration for. ultrasonic examination systems. Supplement 11 provides qualification requirements for full structural overlaid wrought, austenitic piping welds.

Reason for Request

Pursuant to 10 CFR 50.55a, "Codes and Standards," Paragraph (a)(3), relief is requested from the requirements of ASME Code Section XI requirements. The request is based upon restoring the structural integrity of the nozzle to control rod drive end cap weld joint by applying a full structural weld overlay over the weld joint using technically sound welding practices and non-destructive examination (NDE), while limiting repair personnel exposure to the maximum extent practical. Currently, there exist no generically accepted Code approved criteria for a licensee to apply a full structural weld overlay to dissimilar metal welds involving nickel alloys such as Alloy 600, 82 and 182 at ambient temperature.

The following cited ASME Section XI articles identify the actions that would be required if a repair is performed in accordance with the Code without exception:

IWA-4421 (a) and IWA-46 11.1 (a) require removal of the detected flaw. The repair cavity would extend through-wall since outer diameter (OD) removal would be required. Internal diameter (ID) removal of the indication and subsequent weld repair would be impractical due to the need to drain the vessel to perform the repair, and the resultant radiation levels would present unacceptable exposure burden.

IWA-46 10(a) requires that the area to be welded shall be pre-heated to 300°F minimum for GTAW. Since the nozzle will remain full of water, establishing the 300'F minimum pre-heat temperature cannot be achieved.

IWA-46 10(a) also requires the use of thermocouples to monitor process temperature. Due to the personnel exposure associated with the installation and removal of the thermocouples, the nozzle configuration, and because the nozzle will be full of water, a contact pyrometer will be used, in lieu of thermocouples, to provide equivalent temperature monitoring capabilities.

IWA-463 1(b) specifies the surface of the completed weld on the ferritic steel shall not exceed 100 square inches. Restoring the structural integrity with the weld overlay of the end cap-to-nozzle weld may require welding on more than 100 square inches of surface on the low alloy steel base material.

IWA-4633.2(c) specifies the first three layers of the weld shall be deposited with heat inputs within +/- 10% of that used in the procedure qualification test. Subsequent layers shall be deposited using heat input equal to or less than that used for layers beyond the third in the procedure qualification. Code Case N-638-1 (Reference 3) allows for layers beyond the third to exceed the heat input, provided it is in accordance with the procedure qualification records (PQRs).

NLS2010013 Attachment Page 3 of 23 IWA-4633.2(c) also specifies that at.least one layer-of weld reinforcement shall be deposited and then this reinforcement shall be removed,.to be substantially flush with the surface surrounding the weld. The weld -reinforcement will not be removed -flush to the surface.

Appendix VIII provides requirements for performance demonstration for ultrasonic examination systems. Supplement 11 provides qualification requirements for full structural overlaid wrought austenitic piping welds. Appendix VIII, Supplement 11 cannot be implemented as written for ultrasonic examination of structural weld overlay repair.

Code Case N-504-3

" Code Case N-504-3 was prepared specifically to apply a weld overlay to austenitic stainless steel material. An alternative was required to implement the N-504-3 weld overlay methodology due to the specific materials and configuration of the existing nickel-based alloy weld and buttering (Alloy 82 and Alloy 182) and Alloy 600 cap.

• Code Case N-504-3, Requirement (b), requires that the weld overlay shall be low carbon (0.035 percent maximum) austenitic stainless steel. An alternative was required since a nickel-based filler (Alloy 52M) has been selected to be used.

" Code Case N-504-3, Requirement (e), requires that the first two layers of the weld overlay shall have a ferrite content of at least 7.5 FN (Ferrite Number). Cooper Nuclear Station (CNS) does not intend to perform these measurements for this type of overlay on the basis that the nickel-based alloy filler is a fully austenitic material.

Code Case N-504-3, Requirement (h), specifies that a system hydrostatic test shall be performed in accordance with ASME Section XI, IWA-5000 if the flaw penetrates the original pressure boundary. In the event a flaw becomes through-wall, leak testing in accordance with IWA-5000 will be performed.

Code Case N-638-1

• Code Case N-638-1, paragraph 1.0(a), specifies that the maximum weld area on the finished low alloy steel surface shall be 100 square inches. Restoring the structural integrity of the nozzle to end cap weld will require application of the weld overlay on more than 100 square inches of surface on the low alloy steel base material.

" Code Case N-638-1, paragraph 4.0(b), specifies that the final weld surface and the band around the area (to a width of 1.5 times the thickness of the weld (1.5T) or 5 inches, whichever is less) shall be examined using surface and ultrasonic test (UT) methods, when the completed weld has been at ambient temperature for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The UT shall be in accordance with ASME Section XI, Appendix I. Full UT examination of the 1.5T band will not be performed.

NLS2010013 Attachment Page 4-of 23 Code Case N-638-14 paragraph 4.0(c), specifies -that the area from which weld-attached thermocouples have been removed shall be ground and examined using a surface examination method., Thermocouples will not be used. Instead, calibrated pyrometers will be utilized to monitor preheat and interpass temperatures.

Proposed Alternative and Basis for Use The component for which a full structural weld overlay repair may be needed is identified in the following Table 1. The overlay would entirely replace the original pressure boundary of the dissimilar metal welds identified in Table 1.

Table 1 Component Component Material 1 Material 2 Maximum Surface ID Description Area of Weld Overlay (Ferritic side, in )

RCA-BF-1 5 inch Control Rod Nozzle: A- SB-166 260 Drive Return Cap to 508 Class 2 Nozzle N9 Weld I I I The full structural weld overlay will be designed consistent with the requirements of the following:

1. NUREG-0313, Revision 2 (Reference 4; implemented by Nuclear Regulatory Commission (NRC) Generic Letter 88-01, Reference 5).

2. Code Case N-504-3 (Reference 2), "Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping,Section XI, Division 1." Regulatory Guide 1.147, Revision 15 requires the following condition to be met when using Code Case N-504-3:

"The provisions of Section XI, Non-Mandatory Appendix Q, "Weld Overlay Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping Weldments ", must also be met."

CNS will meet the associated requirements contained in Non-mandatory Appendix Q, 2007 Edition (Reference 7).

3. Code Case N-638-1, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1," (Reference 3), listed in Regulatory Guide 1.147, Revision 15, requires the following condition to be met when using Code Case N-638-1:

"UT volumetric examinationsshall be performed with personnel andprocedures qualified for the repairedvolume and qualified by demonstration using representativesamples which

NLS2010013 Attachment.

Page 5 of 23 contain construction type flaws. The acceptance criteriaofNB-5330 in the 1998 Edition through2000Addenda of Section III apply to allflaws identified in the repairvolume."

CNS will implement this limitation.

4. IWB-3640, ASME Section XI 2001, Edition including Addenda through 2003 with Appendix C.

The use of an overlay filler material that provides excellent resistance to stress corrosion cracking (SCC) creates an effective barrier to flaw extension. Also, temper bead welding techniques produce excellent toughness and ductility in the weld heat-affected zone (HAZ) of low alloy steel materials and, in this case, results in compressive residual stresses on the inside surface that help to inhibit further SCC of the original weldment. The design of the overlay for the nozzle to end cap weldment uses methods that are standard in the industry. There are no new or different approaches in this overlay design which would be considered either a first-of-a-kind or inconsistent with previous approaches.

The overlay will be designed as a full structural weld overlay in accordance with Code Case N-504-3. The temper bead welding technique that will be implemented in accordance with Code Case N-638-1 will produce a tough, ductile, corrosion-resistant overlay.

Welder Qualification and Welding Procedures-Use of Alloy 52M All welders and welding operators will be qualified in accordance with ASME Section IX and any special requirements of ASME XI or applicable code cases. Qualified personnel under the vendor's welding program will perform the weld overlay repair.

A weld procedure specification utilizing machine GTAW (with cold wire feed) for welding SFA-5.14, ERNiCrFe-7A, UNS N06054, F-No. 43 (commercially known as Alloy 52M) will be used.

This alloy has nominally 30% chromium, which is significantly greater than Alloy 82 (which nominally contains 20% chromium), and has been accepted by the NRC in NUREG-0313, Revision 2, as a resistant material against intergranular stress corrosion cracking (IGSCC) in the boiling water reactor (BWR).

If repairs to the overlay are required, manual GTAW for welding SFA-5.14, ERNiCrFe-7A, UNS N06054, F-No. 43 (commercially known as Alloy 52M) will be used. In the unlikely event of a through-wall defect, UNS W86152, F No. 43 manual shield metal arc weld rod (commercially known as Alloy 152) will be used to seal any defect if it is greater than 0.125 inch from the P-3 nozzle material before beginning the structural weld overlay using GTAW.

Welding Wire and Electrodes A consumable nickel based welding wire, highly resistant to SCC, is selected as the weld overlay material. This material, Alloy 52M, contains a nominal 30 wt% Cr level that imparts excellent resistance to SCC. Where localized repairs are required, Alloy 52M will also be used.

NLS2010013 Attachment Page 6 of 23 Weld Overlay Design, The weld overlay will extend around the full circumference of the end cap to nozzle weldment location in accordance with NUREG-0313, Revision 2, Code Case N-504-3 and Generic Letter 88-01. The overlay length will extend across the projected flaw intersection with the outer surface beyond the extreme axial boundaries of the flaw. The design thickness and length will be determined in accordance with the guidance provided in Code Case N-504-3 (paragraph f(1))

and ASME Section XI, paragraph IWB-3640, 2001 Edition including Addenda through 2003, and Appendix C for the evaluation methodology for flawed pipe. The overlay will completely cover the area of the flaw and other Alloy 182 or susceptible austenitic stainless steel material with the highly resistant Alloy 52M weld filler material. The overlay length conforms to the guidance of Code Case N-504-3, paragraph f(1), which satisfies the stress and load transfer requirements. A sketch of the weld overlay repair to the nozzle to control rod drive cap weld is presented in Figure 1 at the end of this request.

In order to apply the necessary weld overlay geometry, it will be necessary to weld on the low alloy steel nozzle base material. A temper bead welding approach will be used for this purpose following the guidance of ASME Section XI Code Case N-638-1, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique." This Code Case provides for fabricating machine GTAW temper bead weld repairs to P-No. 3 Group No. 3 nozzle base material at ambient temperature. The temper bead approach was selected because temper bead welding is an acceptable alternative to the requirement for post-weld heat treatment (PWHT) of the HAZ in welds on low alloy steel material. Also, the temper bead welding technique produces excellent toughness and ductility as demonstrated by welding procedure qualification in the HAZ of welds on low alloy steel materials, and, in this case, results in compressive residual stresses on the inside surface, which assists in inhibiting SCC. This approach provides a comprehensive weld overlay repair and increases the volume under the overlay that can be examined.

Pressure Testing The completed repair shall be given a system leakage test in accordance with the CNS Section XI Repair/Replacement Program and in accordance with ASME Section XI, IWB-5220, 2001 Edition, 2003 Addenda. In the event an unexpected through-wall defect is identified, either before or during the repair, the hydrostatic pressure test requirements defined in Code Case N-504-3 will not be used since the requirements for the 2001 Edition, 2003 Addenda will be met for this repair activity.

Pre-heat and PWHT Requirements Pre-heat and PWHT are typically required for welding on low alloy steel material. ASME Section III specifies PWHT on P-No. 3, Group No. 3, base materials unless temper bead welding is performed under limited restrictions (area and depth limits). ASME Section XI, 2001 Edition including Addenda through 2003, IWA-4610(a) specifies 300°F minimum pre-heat be used for temper bead welding. PWHT cannot be performed and the pre-heat requirements would

NLS2010013 Attachment Page 7 of 23, necessitate draining the reactor pressure vessel (RPV) and a portion of the recirculation system piping. This would result in unacceptable radiation exposure of personnel. Therefore, consistent with As Low As Reasonably Achievable practices and prudent utilization of outage personnel, the RPV will not be drained for this activity. The nozzle and connected cap will be full of water.

Basisfor the Alternatives IWA-4421 (a) and IWA-46 11.1 (a) require removal of the detected flaw. The repair cavity would extend through wall since OD removal would be required. The ID is inaccessible due to the thermal sleeve. Therefore, the flaw will not be removed. Structural weld overlays covering flaws are permitted by Code Case N-504-3 provided the necessary weld overlay geometry is used.

IWA-46 10(a) requires that the area to be welded shall be pre-heated to 3 00'F minimum for GTAW. Since the nozzle will remain full of water, establishing the 300'F minimum pre-heat temperature cannot be achieved. Code Case N-638-1, paragraph 1.0(b), provides for machine GTAW temper bead weld repairs to P-No. 3, Group No. 3, nozzle base material at ambient temperature. The ambient temperature temper bead approach was selected because temper bead welding supplants the requirement for PWHT of the HAZ in welds on low alloy steel material.

Also, the temper bead welding technique produces excellent toughness and ductility in the HAZ of welds on low alloy steel materials, as demonstrated by welding procedure qualification.

Welding procedure qualifications have been successfully performed using Alloy 52M welds on P-No. 3, Group No.3, base material using the ambient temperature temper bead technique.

IWA-46 10(a) also requires the use of thermocouples to monitor process temperatures. Due to the personnel exposure associated with the installation and removal of the thermocouples from the nozzle configuration, and because the water in the associated line will not be drained, thermocouples will not be used to verify that pre-heat and interpass temperature limits are met.

In lieu of thermocouples, a contact pyrometer will be used to verify pre-heat temperature and interpass temperature compliance with the welding procedure surveillance (WPS) requirements.

The use of a contact pyrometer provides equivalent temperature monitoring capabilities.

IWA-463 1(b) specifies the surface of the completed weld on the ferritic steel shall not exceed 100 square inches. Restoring the structural integrity with the weld overlay of the control rod drive end cap to nozzle weld will require welding on more than 100 square inches of surface on the low alloy steel base material. The NRC has accepted the increase on surface area up to 500 square inches for Millstone Power Station Unit 3 by letter from Harold K. Chernoff to David A.

Christian dated May 3, 2007 (Reference 8).

In addition, if the 100 square inch surface limit were maintained, the length of weld overlay extension on the nozzle base material would be severely limited on the nozzle side of the joint.

This distance could be justified as sufficient to provide load redistribution from the weld overlay back into the nozzle without violating ASME III stress limits for primary local and bending stresses and secondary and peak stresses for some of the joints. However, this length would not permit a complete UT of the outer 25% of the nozzle thickness as specified by Code Case N-

NLS2010013 Attachment Page 8 of 23 504-3 forthis nozzle to end cap configuration. The overlay may extend to the transition taper of the low alloy steel nozzle if this is necessary to provide adequate structural reinforcement and allow necessary NDE personnel access so that qualified UT of the required volume can be performed.

Code Case N-432-1 (Reference 1) allows temper bead welding on low alloy steel nozzles without limiting the temper bead weld surface area. The two additional conditions required by N-432-1, that are not required by Code Case N-638-1, are that temper bead welds have pre-heat applied and that the procedure qualification be performed on the same specification, type, grade, and class of material. As previously discussed, elevated pre-heat necessitates draining of the RPV. This would result in unacceptable radiation exposure to personnel.

IWA-4633.2(c) specifies that the first three layers of the weld shall be deposited with heat inputs within +/- 10% of that used in the procedure qualification test. Subsequent layers shall be deposited using heat input equal to or less than that used for layers beyond the third in the procedure qualification. Code Case N-638-1 allows for layers beyond the third to exceed the heat input provided it is in accordance with the PQRs.

IWA-4633.2(c) also specifies that at least one layer of weld reinforcement shall be deposited and then this reinforcement shall be removed, to be substantially flush with the surface surrounding the weld. The weld overlay is austenitic and thus, there is no need to remove the final layer.

Also, overlays, by definition, cannot be substantially flush with the surrounding surface.

Overlays are permitted per Code Case N-504-3. The toe of the weld on the low alloy steel nozzle shoulder will be indexed between layers such that proper HAZ tempering will result.

Code Case N-638-1 is approved (with one limitation) for generic use in Regulatory Guide (RG) 1.147, Revision 15 and was developed for both similar and dissimilar metal welding using ambient temperature machine GTAW temper bead technique. The welding methodology of Code Case N-638-1 will be followed for the overlay, whenever welding within the 0.125-inch minimum distance from the low alloy steel nozzle base material.

Code Case N-504-3 is approved (with one limitation) for generic use in RG 1.147, Revision 15 and was developed for welding on and using austenitic stainless steel material. An alternate application for nickel-based and low alloy steel materials is proposed due to the specific configuration of this weldment. The weld overlay proposed is austenitic material having a mechanical behavior similar to austenitic stainless steel. It is also compatible with the existing weld and base materials.

The methodology of Code Case N-504-3 is to be followed, with the following exception.

Alternative to Code Case N-504-3, Requirement (b)

Code Case N-504-3, Requirement (b), requires the weld overlay shall be low carbon (0.035%

maximum) austenitic stainless steel. A consumable welding wire highly resistant to SCC was selected for the overlay material. This material, designated as UNS N06054, FN 43, is a nickel

NLS2010013 Attachment Page 9 of 23 based alloy weld filler material, commonly referred to as Alloy 52M, and will be deposited using the machine GTAW process with cold wire feed. Alloy 52M contains about 30 wt% chromium, which imparts excellent corrosion resistance to the material. By comparison, Alloy 82 is identified as a SCC-resistant material in NUREG-0313, Revision 2, and contains nominally 20 wt% chromium, while Alloy 182 has a nominal chromium content of 15 wt%. With its significantly higher chromium content than Alloy 82, Alloy 52M provides an even higher level of resistance to SCC consistent with the requirements of the Code Case. Therefore, this alternative provides an acceptable level of quality and safety.

Alternative to Code Case N-504-3, Requirement (e)

Code Case N-504-3, Requirement (e), requires the first two layers of the weld overlay to have a ferrite content of at least 7.5 FN. The composition of nickel-based Alloy 52M is such that delta ferrite does not form during welding, because Alloy 52M welds are 100% austenitic and contain no delta ferrite due to the high nickel composition (approximately 60 wt% nickel).

Consequently, delta ferrite measurements will not be performed for this overlay. Therefore, this alternative provides an acceptable level of quality and safety.

Alternative to Code Case N-504-3, Requirement (h)

Code Case N-504-3, Requirement (h), specifies that a system hydrostatic test shall be performed in accordance with IWA-5000 if the flaw penetrates the pressure boundary. Leak testing in accordance with ASME Section XI (2001 Edition with the 2003 Addenda), IWA-5000 and IWB-2500-1, Category B-P, will be performed. Therefore, this alternative provides an acceptable level of quality and safety.

Alternative to Code Case N-638-1 Paragraph 1.0(a)

Code Case N-638-1, paragraph 1.0(a), specifies that the maximum weld area on the finished surface shall be 100 square inches. Restoring the structural integrity with the weld overlay of the nozzle to end-cap weld will require welding on more than 100 square inches of surface on the low alloy steel base material. The weld overlays could, if needed, cover up to 260 square inches.

The maximum surface area is a conservative estimate. The actual surface area is expected to be less, depending on the location of a detected flaw. The NRC has accepted the increase on surface area to 500 square inches for Millstone Power Station Unit 3 (Reference 8).

Code Case N-432-1, "Repair Welding Using Automatic or Machine Gas Tungsten-Arc Welding (GTAW) Temper Bead Technique,Section XI, Division 1," allows temper bead welding on low alloy steel nozzles, without limiting the temper bead weld surface area. The two additional conditions required by N-432-1 that are not required by Code Case N-638-1 are (1) that temper bead welds have preheat applied, and (2) that the procedure qualification be performed on the same specification, type, grade, and class of material. Elevated preheat necessitates draining of the reactor pressure vessel. By removing the water in the nozzle area, and (in vessel) inlet riser,

NLS2010013 AttachmentV Page 10 of 23 a large amount of shielding is removed. The radiation dose rates at the weld overlay location would increase, thereby significantly increasing personnel dose.

The ASME Code committees have recognized that the 100 square inches restriction on the surface area is unnecessarily limiting and Code Case N-638-3 has been issued to increase the surface area limit to 500 square inches. The code case attempts to combine the features of Code Cases N-432 and N-638 into a single code case. The supporting analysis for the code case is documented in Electric Power Research Institute (EPRI) Technical Report 1008454, "Expansion of Temper Bead Repair: Proposed Code Case," which concluded that the residual stresses are not detrimentally changed by increasing the surface area of the repair. The technical basis that justifies exceeding 100 square inches of surface area for repair welds is found in EPRI Technical Report 1003616, "Additional Evaluations to Expand Repair Limits for Pressure Vessels and Nozzles," (Reference 6). This technical report describes an ANSYS Finite Element Analysis conducted on the Nine Mile Point Unit 2 feedwater nozzle weld overlay repair. The analysis consisted of modeling the welding processes for both thermal and mechanical aspects. Two overlays were modeled: one was 100 square inches, the other was extended to blend into the nozzle radius to achieve greater than the 100 square inches surface area repair currently permitted by the ASME Code requirements. Comparison of the residual stresses of the two overlays showed that the effect of extending the overlay to the nozzle radius minimally impacted the residual stress profile and, in some cases, slightly increased the beneficial compressive stresses on the nozzle inner diameter.

Alternative to Code Case N-638-1 Paragraph 4.0(b)

Code Case N-638-1, Paragraph 4.0(b), specifies that the final weld surface and band area [1.5T width or 5 inches, whichever is less, per paragraphl.0 (d)] shall be examined using surface and ultrasonic methods when the completed weld has been at ambient temperature for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. Code Case N-638-1 requires that the final post-weld examinations be performed after completion of welding. The alternative is to begin the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold period following the completion of the third temper bead weld layer on the ferritic base metal. The 48-hour hold period is invoked specifically to permit delayed hydrogen cracking to occur prior to the final NDE. Extensive industry experience has identified no evidence of delayed hydrogen cracking in nuclear applications involving ambient temperature temper bead welding. Absence of cracking is attributed to use of the GTAW machine welding process, and to the extensive process and quality controls present in nuclear welding applications. Revising the start time for the 48-hour period reduces adverse cost and scheduling impacts, while retaining effective assurance that delayed hydrogen cracking has not occurred.

The UT shall be in accordance with ASME Section XI, Appendix I. Surface exams will be performed. IWA-4634 requires UT of the area to be welded only. Any laminar flaws in the weld overlay will be evaluated in accordance with ASME Section XI, Non-mandatory Appendix Q, Paragraph Q-4100 (2007 Edition), except, as allowed by IWB-3132.3 (2001 Ed., 2003 Add.),

any flaws that exceed the acceptance standards of Table IWB-3510-1 (2001 Ed., 2003 Add.) are acceptable for continued service, without repair, if an analytical evaluation, performed in accordance with IWB-3600 (2001 Ed., 2003 Add.), meets the acceptance criteria of IWB-3600.

NLS2010013 Attachment.

Page 11 of 23:

Full UT of the 1.5T band will not be performed. Full ultrasonic examination of the 1.5T band will not be possible due to geometric interferences. The ultrasonic examination may not extend up to the very edge of the overlay. The weld overlay will extend into the blend radius of the nozzle beyond -the-length required by Code Case N-504-3 for structural reinforcement. This extension into the blend radius eliminates a stress riser on the nozzle and may provide additional surface area for ultrasonic examination of the defect area in the original weld. UT examination on the nozzle beyond the overlay will not provide any information regarding the area of the defect that required repair. Additionally, such UT would likely be unsatisfactory when applied to the nozzle blend radius, where the toe of the weld overlay resides. The UT return signal would be difficult to obtain and to interpret. Figures 1 and 2 identify the extent of coverage expected for scans in the circumferential and axial directions. The full weld overlay surface will be scanned. See Table 2 for the examination summary.

Because this is a surface application of a temperbead welding process (specifically performed to minimize heat input into the ferritic steel nozzle), there is minimal impact to the volume of the ferritic shell nozzle material in the area surrounding the weld overlay. Also, no additional useful information can be gained by a volumetric examination of the area beyond the physical boundaries of the weld overlay. The weld and heat affected zone beneath the weld overlay will be volumetrically examined after welding to ensure that sound weld metal has been deposited and that the process did not introduce flaws into the base material. Surface examinations of the weld overlay surface will be performed (See Figure 3 for the examination area). This is sufficient to verify that defects were not introduced in either the ferritic steel nozzle or Alloy 600 (SB-166) end cap due to welding.

Later editions of Section Xl, as well as Code Case N-638-2, have deleted the requirement for the 1.5T examination band for both ultrasonic examination and surface examination. This is consistent with the less restrictive requirements for ultrasonic examination of the ferritic nozzle because hydrogen cracking away from the temper bead weld is not considered a concern. The NDE requirements in these documents apply to any type of welding where a temperbead technique is to be employed (which includes weld repairs of excavated flaws) and is not specifically written for weld overlay. For the weld overlay type of repair, any ferritic steel base material cracking would occur in the HAZ directly below or adjacent to the weld overlay and not in the 1.5T examination band of ferritic material beyond the edges of the weld overlay. If this type of cracking occurs it will be detected by the NDE of the weld overlay and adjacent ferritic steel surfaces as described in the relief request and non-mandatory Appendix Q. Therefore, this alternative provides an acceptable level of quality and safety.

NLS2010013 Attachment Page 12,of 23 Weld Overlay Required Ultrasonic (UT) Examination Coverage Fiaure.I A _B 1 Weld Over-ay

§6 C0N Incone 82 /Inconel 182 Examination Volume A-B-C-D Note:

(1) The UT Axial scan coverage of the Weld Overlay material will only be limited in the taper areas by transducer wedge element size and taper transitions, both of which are outside the Code Required Examination Volume. UT scans will be performed in opposing upstream and downstream directions.

(2) The UT Circumferential scan coverage of the Weld Overlay material is expected to be limited at each edge of the overlay by approximately 0.5" as determined by the dimension of the transducer wedge element and taper transitions. UT scans will be performed in opposing clockwise and counter-clockwise directions.

Weld Reouired (PSI/ISIb Ultrasonic Examination Coversae Examination Volume A-B-C-D Note:

(1) For axial or circumferential flaws, the extent of the examination volume shall extend at least MAin. beyond the as found flaw and at least 1/ in. beyond the toes of the original piping weldment, including weld end butter, where applied.

(2) The Ultrasonic Axial and Circumferential scans will achieve 100% of the Code Required Volume.

NLS2010013 Attachment Page 13 of 23 Weld Overlay (PSI) Liquid Penetrant Examination Coverage Weld Overlay S-B/1,6 aSA 508 C12 Nzl Inconel 182 Nzl (EdCpInconel 82 The weld overlay and adjacent base material for

'1/2 inch from each side of the overlay shall be examined using the Liquid penetrant method.

Alternative to Code Case N-638-1 paragraph 4.0(c)

Code Case N-638-1, paragraph 4.0(c), specifies that the area from which weld-attached thermocouples have been removed shall be ground and examined using a surface examination method. Due to the personnel exposure associated with the installation and removal of the thermocouples, the nozzle configuration, and because the nozzle will be full of water, thermocouples will not be used to verify that the pre-heat and interpass temperature limits are met. In lieu of thermocouples, a contact pyrometer will be used to verify pre-heat temperature and interpass temperature compliance with the WPS requirements. Therefore, this alternative provides an acceptable level of quality and safety.

The use of overlay filler material that provides excellent resistance to SCC develops an effective barrier to flaw extension. Also, temper bead welding techniques produce excellent toughness and ductility in the weld HAZ low alloy steel materials, and in this case, results in compressive residual stresses on the inside surface that help to inhibit further SCC. The design of the overlay for the control rod drive end cap to nozzle weldment uses methods that are standard in the industry. There are no new or different approaches in this overlay design which would be considered either first-of-a-kind or inconsistent with previous approaches. The overlay will be designed as a full structural overlay in accordance with Code Case N-504-3, except as noted above. The temper bead welding technique that will be implemented in accordance with Code Case N-638-1 will produce a tough, ductile, corrosion-resistant overlay. Therefore, this alternative provides an acceptable level of quality and safety.

Appendix VIII, Supplement 11 Appendix VIII provides requirements for performance demonstration for ultrasonic examination systems. Supplement 11 provides qualification requirements for full structural overlaid wrought

NLS2010013 Attachment Page 14 of:23 austenitic piping welds. Appendix VIII, Supplement 11, cannot be implemented as written for ultrasonic examination of structural weld overlay repair. Table 3 includes a discussion of the Performance Demonstration Initiative (PDI) Program alternatives and their bases with respect to Appendix VIII, Supplement 11 requirements. Therefore, this alternative provides an acceptable level of quality and safety.

Examination Requirements NUREG-0313, Revision 2, and Code Case N-504-3, specify UT using methods and personnel qualified in accordance with ASME Section XI, Appendix I. The UT techniques to be used for the final post-weld examination have been qualified through the EPRI NDE Center, which satisfies the requirements of ASME Section XI, Appendix I. Furthermore, NUREG-0313 states that the UT is to be performed in accordance with the requirements of the applicable Edition and Addenda of ASME Section XI. ASME Section XI, 2001 Edition including Addenda through 2003, is the Code of Record for the current Cooper Inservice Inspection Interval. Therefore, the acceptance criteria that will be used for the UT will be IWB-3130, "In-service Volumetric and Surface Examinations," and ASME Section XI (2007 Edition) Non-mandatory Appendix Q, "Weld Overlay Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping Weldments," as clarified under Exceptions to Code Case N-638-1, paragraph 4.0(b).

Although the provisions of Code Case N-638-1, (paragraph 4.0(b)), require that the final post-weld examinations be performed after completion of welding, an alternative to that provision is proposed, and the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold will begin following the completion of the third temper bead weld layer on the ferritic base metal. The 48-hour hold period is invoked specifically to permit delayed hydrogen cracking to occur prior to the final NDE. Extensive industry experience has identified no evidence of delayed hydrogen cracking in nuclear applications involving ambient temperature temper bead welding. Absence of cracking is attributed to use of the GTAW machine welding process, and to the extensive process and quality controls present in nuclear welding applications. Revising the start time for the 48-hour period reduces adverse cost and scheduling impacts, while retaining effective assurance that delayed hydrogen cracking has not occurred. Table 2 summarizes the examination requirements:

Table 2: Summary of Examination Requirements Exam Description Method Technique Reference As found flaw UT PDI Qualified Implementing IWB-3514.4 detection ASME Section XI, Appendix VIII, Supplement 10 Pre-weld UT UT 00 N-504-3 Thickness Surface Prior to PT Color Contrast (Visible) Penetrant IWA-461 1.1 (a) welding N504-3(c)

N-638-1, 4.0(a)

Final Weld Overlay PT Color Contrast (Visible) Penetrant IWA-4634

NLS2010013 Attachment-Page 15 of 23 Exam Description Method Technique Reference Surface N-504-3(j)

N-638-1, 4.0(b)

Final Weld Overlay UT 00 IWA-4634 for Thickness N-504-3(j)

N-638-1, 4.0(b)

Final Weld Overlay UT PDI Qualified Implementing IWA-4634 and outer 25% of the ASME Section XI, Appendix VIII IWB-3514.4 underlying wall Supplement 11 as allowed by this N-504-3(j) thickness volumetric request. (Reference PDI generic N-638-1, 4.0(b)

Pre-service Procedure PDI-UT-8). Appendix Q (2007 Edition)

PDI Program vs. Supplement 11 Relief is requested to allow closer spacing of flaws provided they did not interfere with detection or discrimination. The existing specimens used to date for qualification to the Tri-party (NRC/Boiling Water Reactor Owners Group/EPRI) agreement have a flaw population density greater than allowed by the 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 weld overlay program.

Duration of Proposed Alternative CNS is currently in its Fourth ten-year ISI interval, which began March 1, 2006. This interval will end concurrent with the expiration of Cooper Operating License on January 18, 2014.

Consequently, the requested relief is for the remainder of the current operating license.

Precedents This request is consistent with RI-35, Revision 1, approved by the NRC for CNS for the current 4&h Interval, however limited to only RE24 (Fall 2008). (Adams Accession #ML080370464, TAC #MD8025)

A relief request for Millstone Unit 3 was approved by the NRC in a letter dated May 3, 2007 (Reference 8), including approval of 500 square inch surface area provision on the low alloy steel nozzle (ADAMS Accession No. ML071210024, TAC #MD3379).

Regarding the use of PDI in lieu of Supplement 11 requirements, the NRC has approved requests for several utilities to allow the use of the PDI Program for implementation of Appendix VIII, Supplement 11, requirements for the examination of piping welds with overlays.

The proposed repair activity is consistent with requests previously approved by the NRC to apply overlay repairs at other boiling water reactors, including Duane Arnold (Reference 9), Nine Mile

NLS2010013 Attachment Page 16-of 23 Point Unit 2 (Reference 10), Susquehanna (Reference 11), Pilgrim (Reference 12) and Hope Creek (Reference 13).

References *

1. ASME Case N-432-1, "Repair Welding Using Automatic or Machine Gas Tungsten-Arc Welding (GTAW) Temper Bead Technique,Section XI, Division 1."

2. ASME Case N-504-3, "Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping,Section XI, Division 1."

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

4. NUREG-0313 Revision 2, Date Published: January 1988.

5. NRC Generic Letter 88-01, "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping," January 25, 1988, and Supplement 1, February 4, 1992.

6. EPRI Technical Report 1003616, "Additional Evaluations to Expand Repair Limits for Pressure Vessels and Nozzles," March 2004.

7. ASME Section XI, Nonmandatory Appendix Q, "Weld Overlay Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping Weldments," 2007.

8. Letter from Harold K. Chernoff, NRC, to David A. Christian, Dominion Nuclear, dated May 3, 2007, for the Millstone Power Station Unit 3 (ADAMS Accession No. ML071210024).

9. Letter from L. Raghavan, NRC, to Gary Van Middlesworth, Duane Arnold Energy Center, dated June 12, 2007 (ADAMS Accession No. ML071110007).

10. Letter from Marsha Gamberoni, NRC, to John H. Mueller, Niagara Mohawk Power Corporation, dated March 30, 2000, for Nine Mile Point Station Unit No. 2.

11. Letter from Richard J. Laufer, NRC, to Bryce L. Shriver, PPL Susquehanna, LLC, dated June 22, 2005, for Susquehanna Station (ADAMS Accession No. ML051220568).

12. Letter from John P. Boska, NRC, to Michael Kansler, Entergy Nuclear Operations, Inc.,

dated April 2, 2007, for Pilgrim Nuclear Power Station, (ADAMS Accession No. ML070590479).

13. Letter from Darrell J. Roberts, NRC, to William Levis, PSEG Nuclear, dated August 29, 2005, for Hope Creek Generating Station (ADAMS Accession No. ML051520177).

NLS2010013 Attachment Page.: 17 of 23 Supplement 11-Qualification Requirements PDI .Program:

for Full Structural Overlaid Wrought, The Proposed Alternative to Supplement Austenitic Piping Welds 11 Requirements 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 Alternative: (b) The specimen set shall three specimens having different nominal pipe include specimens with overlays not thicker diameters and overlay thicknesses. They shall than 0.1 inch more than the minimum include the minimum and maximum nominal thickness, nor thinner than 0.25 inch of the pipe diameters for which the examination maximum nominal overlay thickness for procedure is applicable. Pipe diameters within which the examination procedure is a range of 0.9 to 1.5 times a nominal diameter applicable.

shall be considered equivalent. If the Basis: To avoid confusion, the overlay procedure is applicable to pipe diameters of 24 thickness tolerance containedin the last in. or larger, the specimen set must include at sentence was reworded and the phrase "and least one specimen 24 in. or larger but need the remaindershall be alternativeflaws" was not include the maximum diameter. The added to the next to last sentence in specimen set must include at least one paragraph1.1 (d)(1).

specimen with overlay thickness within -0.1 in. to +0.25 in. of the maximum nominal overlay thickness for which the procedure is applicable.

(d) Flaw Conditions (1) Base metalflaws. All flaws must be cracks Alternative: (1) ... must be in or...

in or near the butt weld heat-affected zone, intentional overlay fabrication flaws shall not open to the inside surface, and extending at interfere with ultrasonic detection or least 75% through the base metal wall. Flaws characterization of the base metal flaws.

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

containing IGSCC shall be used when Alternative flaw mechanisms, if used, shall available. provide crack-like reflective characteristics and shall be limited by the following:

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

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

Basis: This paragraphrequiresthat all base metalflaws be cracks. Implanting a crack

NLS2010013 Attachment Page .18 of 23 Supplement 11-Qualification Requirements PDI Program:

for Full Structural Overlaid Wrought The Proposed Alternative to Supplement Austenitic Piping Welds 11 Requirements requires excavation of the base materialon at least one side of the flaw. While this may be satisfactoryforferriticmaterials,it does not produce a useable axialflaw in austenitic materialsbecause the sound beam, which normally passes only through base material,must now travel through weld materialon at least one side, producingan unrealisticflaw response. To resolve this issue, the PDIprogram revised this paragraphto allow use of alternativeflaw mechanisms under controlledconditions. For example, alternativeflaws shall be limited to when implantation of cracks precludes obtainingan effective ultrasonic response, flaws shall be semi ellipticalwith a tip width of less than or equal to 0. 002 inches, and at least 70% of the flaws in the detection and sizing test shall be cracks and the remainder shall be alternativeflaws. To avoid confusion, the overlay thickness tolerance contained in paragraph1. (b) last sentence, was reworded and the phrase "and the remaindershall be alternativeflaws" was added to the next to last sentence. Paragraph

1. l(d)(1) includes the statement that intentionaloverlayfabricationflaws shall not interfere with ultrasonicdetection or characterizationof the base metal flaws.

NLS2010013 Attachment Page 19 of,23 (e) Detection Specimens (1) At least 20% but less than 40% of the flaws Alternative: (1) At least 20% but less than shall be oriented within +20 deg. of the pipe 40% of the base metal flaws shall axial direction. The remainder shall be be oriented within +/-20' of the pipe axial oriented circumferentially. Flaws shall not be direction. The remainder shall be oriented open to any surface to which the candidate has circumferentially. Flaws shall not be open to physical or visual access. The rules of IWA- any surface to which the candidate has 3300 shall be used to determine whether physical or visual access.

closely spaced flaws should be treated as Basis: The requirementfor axially oriented single or multiple flaws. overlayfabricationflaws was excludedfrom the PDIProgramas an improbable scenario.

Weld overlays.are typically applied using automated GTA W techniques with the filler metal applied in a circumferentialdirection.

Because resultantfabricationinduced discontinuitieswould also be expected to have major dimensions oriented in the circumferentialdirection axial overlay fabricationflaws are unrealistic. The requirementfor using IWA-3300 for proximityflaw evaluation was excluded; insteadindication will be sized based on their individualmerits.

(2) Specimens shall be divided into base and Alternative: (2) Specimens shall be divided over-lay grading units. Each specimen shall into base metal and overlay fabrication contain one or both types of grading units. 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 of "metal" and "fabrication" provides clarification. Flaw identification is improved by ensuring flaws are not masked by other flaws.

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

Basis: The phrase "andbase metal on both sides," was inadvertently included in the

NLS2010013 Attachment Page 20 of 23 description of a base metal gradingunit. The PDIprogram intentionally excludes this requirement because some of 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 of alternativeFlaw mechanisms.

Modified to require that a base metal grading unit include at least 1inch of the length of the overlaid weld, ratherthan 3 inches.

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

material shall not be used as part of any Basis: Substituted terms provide clarification overlay grading unit. and are consistent with ld(1) above. The PDI program adjustsfor this conservative change for excluding this type grading unit.

(a)(3) When a base grading unit is designed to Alternative: (a)(3) Sufficient unflawed be unflawed, at least I in. of unflawed overlaid overlaid weld and base metal shall exist on all weld and base metal shall exist on either side sides of the grading unit to preclude of the base grading unit. The segment of weld interfering reflections from length used in one base grading unit shall not adjacent flaws.

be used in another base grading unit. Base Basis: Modified to requiresufficient unflawed grading units need not be uniformly spaced overlaid weld and base metal to exist on all around the specimen. sides of the grading unit to preclude interferingreflectionsfrom adjacentflaws, rather than the I inch requirement.

(b)(1) An overlay grading unit shall include the Alternative: (b)(1) An overlay fabrication overlay material and the base metal-to-overlay grading unit shall include the overlay material interface of at least 6 sq. in. The overlay and the base metal-to-overlay interface for a grading unit shall be rectangular, with length of at least 1 inch.

minimum dimensions of 2 in. Basis: The PDIprogram reduces the base metal-to-overlay interface to at least 1 inch (in lieu of a minimum of 2 inches) and eliminates the minimum rectangular dimension. This criterion is necessary to allow use of existing examination specimens that were fabricatedin orderto meet NRC Generic Letter 88-01. This criterionmay be more challengingthan the ASME Code because of the variabilityassociatedwith the shape of the grading unit.

NLS2010013 Attachment Page 21 of 23 (b)(2) An overlay grading unit designed to be Alternative: (b)(2) Overlay fabrication unflawed shall be surrounded by unflawed. grading units designed to be unflawed shall overlay material and unflawed base metal-to- be separated by unflawed overlay material overlay interface for at least I in. around its and unflawed base metal-to-overlay interface-entire perimeter. The specific area used in one for at least 1 inch at both ends. Sufficient overlay grading unit shall not be used in unflawed overlaid weld and base metal shall another overlay grading unit. Overlay grading exist on both sides of the overlay fabrication units need not be spaced uniformly about the grading unit to preclude interfering reflections specimen. from adjacent flaws. The specific area used in one overlay fabrication grading unit shall not be used in another overlay fabrication grading unit. Overlay fabrication grading units need not be spaced uniformly about the specimen.

Basis: Paragraph1.1 (e)(2)(b)(2) states that overlayfabricationgradingunits designed to be unflawed shall be separatedby unflawed overlay material and unflawed base metal-to-overlay interfacefor at least I inch at both I ends, ratherthan around its entire perimeter.

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

Basis: Clarified the guidancefor initial procedure qualificationsversus qualifying new values of essentialvariables.

(I) Sizing Specimen i

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

NLS2010013 Attachment Page 22 of 23 Basis: Clarifiedthe guidancefor initial procedurequalificationsversus qualifying new values of essentialvariables and is consistent with ld(1) above..

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

circumferentially. Basis: Clarifiedwording to be consistent with ld(1) above.

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

Basis: Clarifiedwording to be consistent with ld(1) above.

2.0 CONDUCT OF PERFORMANCE DEMONSTRATION The specimen inside surface and identification Alternative: The specimen ...prohibited. The shall be concealed from the candidate. All overlay fabrication flaw test and the base examinations shall be completed prior to metal flaw test may be performed separately.

grading the results and presenting the results to Basis: Clarifiedwording to describeprocess.

the candidate. Divulgence of particular specimen results or candidate viewing of unmasked specimens after the performance demonstration is prohibited.

2.1 Detection Test.

Flawed and unflawed grading units shall be Alternative: Flawed... (base metal or overlay randomly mixed. Although the boundaries of fabrication).. each specimen.

specific grading units shall not be revealed to Basis: Clarifiedwording similar to l(e)2 the candidate, the candidate shall be made above.

aware of the type or types of grading units (base or overlay) that are present for each specimen.

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

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

of the flaw that is in the outer 25% of the base Basis: Clarifiedwordingfor consistency.

wall thickness.

2.3 Depth Sizing Test.

3.0 ACCEPTANCE CRITERIA 3.1 Detection Acceptance Criteria Examination procedures, equipment, and Alternative: Examination procedures are personnel are qualified for detection when the qualified for detection when:

results of the performance demonstration a. All flaws within the scope of the procedure

NLS2010013 Attachment Page 23 of 23 satisfy the acceptance criteria of Table Vlll- are detected and the results of the S2-1 for both detection and false calls. The performance demonstration satisfy the criteria shall be satisfied separately by the acceptance criteria of Table VIIIS2-1 for false demonstration results for base grading units calls.

and for overlay grading units. b. At least one successful personnel demonstration has been performed meeting the acceptance criteria defined in (c).

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

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

Basis: Clarifiedwording 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 Alternative: (a) The.. .base metal flaws measurements, as compared to the true flaw is.. .position.

lengths, is less than or equal to 0.75 inch. The Basis: Clarifiedwording to be consistent with length of base metal cracking is measured at ld(J) above.

the 75% through-base-metal position.

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

the overlay material by at least 0.1 inch are Basis: The requirementfor reportingall reported as being intrusions into the overlay extensions of crackinginto the overlay is material. omittedfrom the PDIProgram because it is redundant to the RMS calculationsperformed in paragraph3.2(c) and its presence adds confusion and ambiguity to depth sizing as required by paragraph3.2(c). This also makes the weld overlay program consistent with the supplement 2 depth sizing criteria.

4 ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© 4

ATrACHMENT 3 LIST OF REGULATORY COMMITMENTS© Correspondence Number: NLS2010013 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITMENT COMMITTED DATE COMMITMENT NUMBER OR OUTAGE None N/A N/A 4 .4.

4 4.

4 4.

I 4-4 4.

I PROCEDURE 0.42 REVISION 24 PAGE 18 OF 25 ý