ML062630142

Supplement to Proposed Alternative to the American Society of Mechanical Engineers Code,Section XI, Repair Requirements

ML062630142
Person / Time
Site:	Cook
Issue date:	09/15/2006
From:	Jensen J Indiana Michigan Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP:NRC:6055-12, TAC MD2119
Download: ML062630142 (22)

Text

Indiana Michigan Power INDIANA Cook Nuclear Plant MICHNIGAN One Cook Place Bridgman, MI 49106 EUWRI* AEPcom A unit ofAmerican Electric Power September 15, 2006 AEP:NRC:6055-12 10 CFR 50.55a Docket No. 50-315 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-P1-17 Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Unit 1 SUPPLEMENT TO PROPOSED ALTERNATIVE TO THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE, SECTION XI REPAIR REQUIREMENTS

References:

1. Letter from Joseph N. Jensen, Indiana Michigan Power Company (I&M), to U. S.

Nuclear Regulatory Commission (NRC) Document Control Desk,

'Donald C. Cook Nuclear Plant Unit 1, Proposed Alternative to the American Society of Mechanical Engineers Code,Section XI Repair Requirements,"

AEP:NRC:6055-08, Accession Number ML061710464, dated June 9, 2006.

2. Electronic mail message from Peter S. Tam, NRC, to Susan D. Simpson, I&M, "D. C. Cook: Draft RAI on Preemptive Weld Overlay (TAC MD2119),"

Accession Number ML062360003, dated August 23, 2006.

By Reference 1, Indiana Michigan Power Company (I&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1, proposed an alternative to the repair requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) pursuant to 10 CFR 50.55a(a)(3)(i). The proposed alternative was requested because during the next CNP Unit 1 refueling outage, I&M will be performing full structural preemptive weld overlays (PWOLs) on pressurizer nozzle safe end to nozzle welds where NiCrFe Alloy 82/182 was originally used to weld the safe ends thereto.

By Reference 2, the Nuclear Regulatory Commission (NRC) staff proposed questions that were discussed in conference calls with I&M personnel on August 25, 2006, and September 14, 2006. As a result of the conference calls, I&M is supplementing the proposed alternative requested in Reference 1. Differences between this supplement and the Reference 1 proposed alternative are indicated by margin marks in Attachment 1 of this letter. In addition, during the conference calls, I&M committed to complete stress analysis summaries of the PWOLs prior to restart of Unit 1, to Aco-2

U. S. Nuclear Regulatory Commission AEP:NRC:6055-12 Page 2 provide the summaries within four weeks after restart from the Unit 1 (Fall 2006) refueling outage, and to provide the PWOL ultrasonic examination results within 14 days following completion of the last examination. These commitments are documented in Attachment 2 to this letter.

I&M requests approval of the proposed alternative by September 22, 2006, to support the Unit 1 outage schedule. Commitments made in this letter are identified in Attachment 2. Should you have any questions, please contact Ms. Susan D. Simpson, Regulatory Affairs Manager, at (269) 466-2428.

Sincerely, o0seph N. Jensen Site Support Services Vice President RGV/jen Attachments: 1. 10 CFR 50.55a Relief Request - ISIR-21, Proposed Alternative for Preemptive Weld Overlays in Accordance with 10 CFR 50.55a(a)(3)(i)

2. Regulatory Commitments c: R. Aben - Department of Labor and Economic Growth J. L. Caldwell - NRC Region III K. D. Curry - AEP Ft. Wayne, w/o attachments J. T. King - MPSC, w/o attachments MDEQ - WHMD/RPMWS, w/o attachments NRC Resident Inspector P. S. Tam- NRC Washington DC

ATTACHMENT 1 to AEP:NRC:6055-12 10 CFR 50.55a RELIEF REQUEST -ISIR-21 PROPOSED ALTERNATIVE FOR PREEMPTIVE WELD OVERLAYS IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i) 1.0 REASON FOR THE REQUEST Dissimilar metal welds (DMWs), consisting primarily of Alloy 82/182 weld material, are frequently used in pressurized water reactor (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 (PRZ).

With this request, Indiana Michigan Power Company (I&M) is proposing to take a proactive approach on the Donald C. Cook Nuclear Plant (CNP) Unit 1 PRZ to apply a preemptive weld overlay (PWOL) on the PRZ nozzle safe end to nozzle DMWs to mitigate the occurrence of PWSCC prior to detectable evidence of PWSCC. Structural weld overlays (WOLs) have been used for several years on both boiling water reactors and PWRs to arrest existing flaws from propagating while establishing a new structural pressure boundary with crack-resistant material.

In some cases, WOLs have been used to reestablish structural integrity of the DMW containing through wall leaking flaws. The PWOLs will also facilitate ultrasonic examination (UT) 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 machine Gas Tungsten-Arc Welding (GTAW) process and using the ambient temperature temper bead method with ERNiCrFe-7, UNS N06052 (Alloy 52) or ERNiCrFe-7A, UNS N06054 (Alloy 52M 1 ) weld metal. Manual GTAW, using Alloy 52 or Alloy 52M, is only planned to be utilized subsequent to the PWOLs being essentially completed. Manual GTAW may be used if local repairs of PWOL weld defects are necessary or additional weld metal is required locally to form the final PWOL contour.

As discussed herein, there is no comprehensive criterion for a licensee to apply a WOL 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 XI, 1989 Edition, no Addenda, IWA-4000, is used for the CNP Unit 1 Section XI Repair/Replacement Program, it does not have the needed requirements for this type of weld overlay repair. The latest Nuclear Regulatory Commission (NRC) approved ASME Code also does not have the needed requirements for this type of overlay. Repair/replacement activities associated with WOLs of this type are required to address The material supplier's weld wire designation is 52MS. The "S" designates the process route that converts the hot-rolled billet into finished cold-drawn wire. The material properties are not affected.

to AEP:NRC:6055-12 Page 2 the materials, welding parameters, personnel radiation exposure concerns, operational constraints, examination techniques, and procedure requirements.

2.0 ASME CODE COMPONENTS AFFECTED Code Class: Class 1 Code

References:

ASME Section XI, 1989, no Addenda (Inservice Inspection Code)

ASME Section III, 1965 Edition, including Addenda through Winter 1966 (Construction Code)

ASME Section XI, 1995 Edition, including Addenda through 1996, Appendix VIII, Supplement 11 (Qualification Requirements)

ASME Section III, 1998 Edition, including Addenda through 2000 (Repair and Inspection Code)

ASME Code Case N-416-1 (Hydrostatic Testing Alternatives)

ASME Code Case N-460 (Examination Coverage)

ASME Code Case N-504-2 (Weld Overlay)

Examination Categories: B-F and B-J Item Numbers: B5.40 and B9.11

==

Description:==

PWOLs for PRZ Spray, Safety, Relief and Surge Nozzle Safe End to Nozzle DMWs and PWOLs for the Elbow to Safe End Welds Component Number: 1-PRZ-20 1-PRZ-21 1-PRZ-22 1-PRZ-24 1-PRZ-25 1-RC-5-05F 1-RC-6-01F 1-RC-7-01F 1-RC-8-O1F 1-RC- 10-39F 3.0 GENERAL DESCRIPTION CNP Unit 1 is in the third ten-year inservice inspection interval using the 1989 Edition of Section XI of the ASME Code.Section XI, IWA-4120, states:

(a) "Repairs shall be performed in accordance with the Owner's Design Specification and the original Construction Code of the component or system. Later Editions and Addenda of the Construction Code or of Section III, either in their entirety or portions thereof, and Code Cases may be used. If repair welding cannot be performed in accordance with these requirements, the applicable alternative requirements of IWA-4500 and the following may be used:..."

The original construction code for the PRZ is ASME Code, Section I1, 1965 Edition, Class A, including Addenda through Winter 1966 for CNP Unit 1. The 1998 Edition, ASME Code Section III, including Addenda through 2000, would require welding in accordance with NB-4622. 11, 'Temper Bead Weld Repair to Dissimilar Metal Welds or Buttering."

to AEP:NRC:6055-12 Page 3 4.0 APPLICABLE CODE REQUIREMENTS FOR WHICH RELIEF IS REQUESTED

1. ASME Section XI, 1989 Edition, no Addenda, IWA-4500.

2. Not Used.

3. NRC conditionally-approved Code Case N-504-2 with the condition as specified in RG 1.147, Revision 14.

4. ASME Section XI, 1995 Edition including Addenda through 1996, Appendix VIII, Supplement 11.

5.0 PROPOSED ALTERNATIVE

SUMMARY

AND BASIS FOR USE I&M proposes using PWOLs designed in accordance with Code Case N-504-2 (Reference 1) with the modifications proposed in Table 1. Code Case N-504-2, which the NRC finds acceptable if ASME Section XI, 2005 Addenda, Appendix Q, requirements are met, 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 PWOLs 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 PWOL configuration is shown in Figure 1.

The temper bead welding technique for the specified nozzles connecting DMWs will be implemented using an alternate methodology similar to that described in Code Case N-638-1.

The differences between the Code Case N-638-1 methodology and the proposed alternative are described in Table 2. The ultrasonic examination (UT) of the completed PWOL will be accomplished in accordance with ASME Section XI, 1995 Edition with the 1996 Addenda, Appendix VIII, Supplement 11, with the modifications described in Table 3 used to comply with the Performance Demonstration Initiative (PDI) program.

6.0 DURATION OF THE PROPOSED ALTERNATIVE The duration of the proposed alternative is the remaining service life of the component, including the period of extended operation.

7.0 PRECEDENTS Similar relief requests have been previously approved for AmerGen Energy Company for its Three Mile Island Nuclear Station, Unit 1 (Reference 3), Constellation Energy's Calvert Cliffs Nuclear Power Plant, Unit 2 (Reference 4), CNP Unit 1 (References 5 and 6), PPL Susquehanna, LLC's Susquehanna Steam Electric Station, Unit 1 (Reference 7), and Dominion Nuclear to AEP:NRC:6055-12 Page 4 Connecticut's Millstone Power Station Unit 3 (Reference 8). These requests were associated with welding over detected flaws outside the acceptance criteria of Section XI.

A similar CNP Unit 2 request (Reference 9) was verbally approved for the CNP Unit 2, Cycle 16 refueling outage.

8.0 CONCLUSION

It is I&M's opinion that the application of PWOLs using the proposed alternative to the ASME Code and the use of PDI provide an acceptable level of quality and safety in accordance with the requirements of 10 CFR 50.55a(3)(i).

9.0 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. 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 J. 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 Inservice Inspection (ISI) Interval (TACNo. MC101)," 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 (TAC Nos. MC6219 and MC6220)," Accession Number ML051930316, dated July 20, 2005.

5. Letter from L. Raghavan, NRC, to Mano K. Nazar, I&M, 'Donald C. Cook Nuclear Plant, Unit 1 (DCCNP-1) - Alternatives Regarding Repair of Weld 1-PZR-23 on Pressurizer Nozzle to Valve Inlet Line (TAC No. MC6704)," Accession Number ML053220019, dated December 1, 2005.

6. Letter from L. Raghavan, NRC, to Mano K. Nazar, I&M, 'Donald C. Cook Nuclear Plant, Unit 1 - Alternative to Repair Requirements of Section XI of the American Society of Mechanical Engineers Code (TAC No. MC6751)," Accession Number ML051720006, dated June 27, 2005.

7. 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 XI, Appendix VIII, Supplement 11, Requirements and Code Cases N-504-2 and N-638 Requirements (TAC Nos. MC2450, MC2451 and MC2594)," Accession Number MLO51220568, dated June 22, 2005.

to AEP:NRC:6055-12 Page 5

8. Letter from Darrell J. Roberts, NRC, to David A. Christian, Dominion Nuclear Connecticut, 'Millstone Power Station, Unit No. 3 - Issuance of Relief from Code Requirements (TAC No. MC8609)

9. Letter from Joseph N Jensen, I&M, to NRC Document Control Desk,

'Donald C. Cook Nuclear Plant Unit 2, Proposed Alternative to the American Society of Mechanical Engineers Code,Section XI Repair Requirements, Request for Additional Information," AEP:NRC:6055, Accession Number ML060620063, dated March 1, 2006.

10. Letter from John N. Hannon, NRC, to E. E. Fitzpatrick, I&M, "D. C. Cook, Units 1 and 2, Requesting Approval of Code Case N-416-1 as an alternative to the Required Hydrostatic Pressure Test (TAC Nos. M92377 and M92345)," dated July 24, 1995.

Attachment I to AEP:NRC:6055-12 Page 6

ýSal Eund fSA4U2 F31k9 A921 R~ootA182 Betlane JCarton Steel joz SA-flC Grade ViCC)

FigureI - Typical PWOL Configuration to AEP:NRC:6055-12 Page 7 A B-Dy xrc~tw T t

Examination Volume A-B-C-D Figure 2 Acceptance Examination Volume to AEP:NRC:6055-12 Page 8 TABLE 1 DESIGN/MATERIALINONDESTRUCTIVE EXAMINATION Modifications to Code Case N-504-2 and ASME Section XI, Appendix Q Code Case N-504-2 and ASME Section XI Proposed Modifications Appendix Q (b) Reinforcement weld metal shall be low Modification: Weld overlay filler metal shall carbon (0.035% [percent] maximum) be an austenitic nickel alloy (28% Cr austenitic stainless steel applied 360 degrees minimum) applied 360 degrees around the around the circumference of the pipe, and shall circumference of the item, and shall be be deposited in accordance with a qualified deposited using a Welding Procedure welding procedure specification identified in Specification for groove welding, qualified in the Repair Program [essentially same as accordance with the Construction Code and Q-2000(a)]. Owner's Requirements and identified in the Repair/Replacement Plan.

Basis: Industry operational experience has shown that PWSCC in Alloy 82/182 will blunt at the interface with stainless steel base metal, ferritic steel base metal, or Alloy 52/52M/152 weld metal.

(e) The weld reinforcement shall consist of a Modification: There is no requirement for minimum of two weld layers having delta ferrite, and delta ferrite measurements as-deposited delta ferrite content of at least will not be performed for this overlay.

7.5 FN. The first layer of weld metal with delta ferrite content of at least 7.5 FN shall constitute Basis: The deposited Alloy 52 or Alloy 52M the first layer of the weld reinforcement design weld metal is 100% austenitic and contains no thickness. Alternatively, first layers of at least delta ferrite due to the high nickel composition 5 FN may be acceptable based on evaluation (approximately 60% nickel).

[essentially the same as Q-2000(d) except if 0.02% carbon is used, evaluation of 5 FN acceptability not required].

(h) The completed repair shall be pressure Modification: In lieu of hydrostatic testing, a tested in accordance with IWA-5000. If the system leakage test and a UT of the weld flaw penetrated the original pressure boundary overlay shall be performed in accordance with prior to welding, or if any evidence of the flaw the Third Interval ISI Program and ASME penetrating the pressure boundary is observed Code Case N-416-1.

during the welding operation, a system hydrostatic test shall be performed in Basis: Code Case N-416-1 has been approved accordance with IWA-5000. If the system for use at CNP as an alternative to hydrostatic pressure boundary has not been penetrated, a testing (Reference 10).

system leakage, inservice, or functional test shall be performed in accordance with IWA-5000.

to AEP:NRC:6055-12 Page 9 Code Case N-504-2 and ASME Section XI Proposed Modifications Appendix Q The repair shall be performed in accordance See Table 2.

with a Repair Program satisfying the requirements of IWA-4000 in the Edition and Addenda of Section XI applicable to the plant in-service inspection program, or later Edition and Addenda.

Attachment I to AEP:NRC:6055-12 Page 10 TABLE 2 AMBIENT TEMPERATURE TEMPER BEAD WELDING Code Case N-638-1 and Proposed Alternative Methodology Differences Code Case N-638-1 Proposed Alternative 1.0 GENERAL REQUIREMENTS (a) The maximum area of an individual weld The maximum area of an individual weld based based on the finished surface shall be on the finished surface over the ferritic material 100 square inches, and the depth of the weld shall be 300 square inches.

shall not be greater than one-half of the ferritic base metal thickness. Basis: The PWOL will require welding on more than 100 square inches of surface on the surge nozzle carbon steel base material. The PWOL will extend to the transition taper of the carbon steel nozzle so that qualified UT of the required volume can be performed There have been a number of temper bead WOL repairs applied to safe-end to nozzle welds in the nuclear industry, and a WOL repair having a 300 square inch surface was recently approved for the Susquehanna Steam Electric Station (Reference 7).

ASME Code Case N-432-1, which is approved for use in RG 1.147, allows temper bead welding on carbon and low alloy ferritic steel nozzles without limiting the temper bead weld surface area. The two additional conditions required by Code Case N-432-1 that are not required by Code Case N-638-1 are that temper bead welds have preheat applied and that the procedure qualification be performed on the same specification, type, grade, and class of material.

The elevated preheat would present a radiation exposure burden when performing the repair.

4.0 EXAMINATION (b) The final weld surface and the band Modification: For the PWOLs, UT of the 1.5T around the area defined in paragraph 1.0(d) band will not be performed.

shall be examined using surface and ultrasonic methods when the completed weld Basis: For the application of the PWOL repair has been at ambient temperature for at least addressed in this request, it is not practical to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The ultrasonic examination shall be perform a meaningful UT of the required band in accordance with Appendix I. of base material because of the existing nozzle configuration shown in Figure 1. This Code to AEP:NRC:6055-12 Page 11 Code Case N-638-1 Proposed Alternative Case applies to any type of welding where a temper bead technique is to be employed and is not specifically written for a WOL repair.

Experience from CNP Unit 2 shows the 1.5T examination causes increased dose, outage time, and cost without a commensurate increase in safety. The base material is cast carbon steel and not subject to weld stress residual cracking.

Indications in this type of material are generally casting inclusions which preclude meaningful examination.

IWA-4534 requires UT of the weld region only.

The Code Case requirements are based on repair to material with flaws that have been removed prior to welding thereon. Therefore, there is a concern for other incipient or existing flaws in the immediate area which may not have been properly cleared prior to welding possibly increasing in size as a result of welding.

The first purpose of the examination is to detect flaws that may be revealed as a result of the repair. In this case, there are no known flaws in the ferritic steel base metal that is being repaired.

For the PWOL, the primary potential concern would be flaws occurring in the heat affected zone adjacent to and beneath the weld in the nozzle carbon steel base material due to welding thereon. UT examination of the PWOL (welded region) will be performed. Dye penetrant examination of both the weld and 1.5T band on the ferritic steel nozzle will be performed. This is sufficient to verify that defects have not been induced in the ferritic carbon steel nozzle material due to the welding process.

Acceptance Examination The examination volume in Figure 2 shall be ultrasonically examined to assure adequate fusion (i.e., adequate bond) with the base metal and to detect welding flaws, such as interbead lack of fusion, inclusions, or cracks. The interface C-D shown between the overlay and

Attachment I to AEP:NRC:6055-12 Page 12 Code Case N-638-1 Proposed Alternative the weld includes the bond and the heat affected zone from the overlay. For ambient temperature temper bead welding, the ultrasonic examination shall be conducted at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the completed overlay has returned to ambient temperature. Planar flaws shall meet the preservice examination standards of Table IWB-3514-2. In applying the acceptance standards, wall thickness "tw" shall be the thickness of the weld overlay. Laminar flaws shall meet the following:

Laminar flaws shall meet the acceptance standards of Table IWB-3514-3 with the additional limitation that the total laminar flaw shall not exceed 10 percent of the weld surface area and that no linear dimension of the laminar flaw area exceeds 3.0 inches.

The reduction in coverage of the examination volume in Figure 2 due to laminar flaws shall be less than 10 percent.

The dimensions of the uninspectable volume are dependent on the coverage achieved with the angle beam examination of the overlay.

Any uninspectable volume in the weld overlay shall be assumed to contain the largest radial planar flaw that could exist within that volume. This assumed flaw shall meet the inservice examination standards of Table IWB-3514-2. Alternately, the assumed flaw shall be evaluated and shall meet the requirements of IWB-3640. Both axial and circumferential planar flaws shall be assumed.

Basis: The context of the original Code Case N-638 was to perform repair welds in vessels and other highly restrained configurations. The PWOL is a different application of the ambient temper bead welding and this alternative acceptance criterion is specific to weld overlays.

The inspection techniques are qualified to specifically detect and characterize defects in to AEP:NRC:6055-12 Page 13 Code Case N-638-1 Proposed Alternative weld overlays (Table 3). This concept was discussed in NUREG-0313, Revision 2,

'Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping."

to AEP:NRC:6055-12 Page 14 TABLE 3 Modifications to Appendix VIII, Supplement 11 Appendix VIII, Supplement 11 PDI Modification 1.0 SPECIMEN REQUIREMENTS (b) The specimen set shall consist of at least (b) The specimen set shall consist of at least three specimens having different nominal pipe three specimens having different nominal pipe diameters and overlay thicknesses. They shall diameters and overlay thicknesses. They shall include the minimum and maximum nominal include the minimum and maximum nominal pipe diameters for which the examination pipe diameters for which the examination procedure is applicable. Pipe diameters within a procedure is applicable. Pipe diameters within a range of 0.9 to 1.5 times a nominal diameter range of 0.9 to 1.5 times a nominal diameter shall be considered equivalent. If the procedure shall be considered equivalent. If the procedure is applicable to pipe diameters of 24 inches or is applicable to pipe diameters of 24 inches or larger, the specimen set must include at least one larger, the specimen set must include at least one specimen 24 inches or larger but need not specimen 24 inches or larger but need not include the maximum diameter. The specimen include the maximum diameter.

set must include at least one specimen with overlay thickness within -0.1 inches to +0.25 The specimen set shall include specimens with inches of the maximum nominal overlay overlays not thicker than 0.1 inches more than thickness for which the procedure is applicable, the minimum thickness, nor thinner than 0.25 inches of the maximum nominal overlay thickness for which the examination procedure is applicable.

(d) Flaw Conditions (1) Base metal flaws. All flaws must be cracks (1) Base metal flaws. All flaws must be in or in or near the butt weld heat-affected zone, open near the butt weld heat-affected zone, open to the to the inside surface, and extending at least 75% inside surface, and extending at least 75%

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

[intergranular stress corrosion cracking] shall cracks and the remainder shall be alternative be used when available, flaws. Alternative flaw mechanisms, if used, shall provide crack-like reflective characteristics and shall be limited by the following:

to AEP:NRC:6055-12 Page 15 Appendix VIII, Supplement 11 PDI Modification (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 semielliptical with a tip width of less than or equal to 0.002 inches.

(e) Detection Specimens (1) At least 20% but less than 40% of the flaws (1) At least 20% but less than 40% of the base shall be oriented within +20 degrees of the pipe metal flaws shall be oriented within +/-20 degrees axial direction. The remainder shall be oriented of the pipe axial direction. The remainder shall circumferentially. Flaws shall not be open to any be oriented circumferentially. Flaws shall not be surface to which the candidate has physical or open to any surface to which the candidate has visual access. The rules of IWA-3300 shall be physical or visual access.

used to determine whether closely spaced flaws should be treated as single or multiple flaws.

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

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

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

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

to AEP:NRC:6055-12 Page 16 Appendix VIII, Supplement 11 PDI Modification (a)(3) When a base grading unit is designed to be (a)(3) Sufficient unflawed overlaid weld and unflawed, at least 1 inch of unflawed overlaid base metal shall exist on all sides of the grading weld and base metal shall exist on either side of unit to preclude interfering reflections from the base grading unit. The segment of weld adjacent flaws.

length used in one base grading unit shall not be used in another base grading unit. Base grading units need not be uniformly spaced around the specimen.

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

dimensions of 2 inches.

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

(b)(3) Detection sets shall be selected from Table (b)(3) Detection sets shall be selected from VII-S2-1. The minimum detection sample set is Table VIII-S2-1. The minimum detection five flawed base grading units, ten unflawed base sample set is five flawed base metal grading grading units, five flawed overlay grading units, units, ten unflawed base metal grading units, five and ten unflawed overlay grading units. For flawed overlay fabrication grading units, and ten each type of grading unit, the set shall contain at unflawed overlay fabrication grading units. For least twice as many unflawed as flawed grading each type of grading unit, the set shall contain at units. least twice as many unflawed as flawed grading units. For initial procedure 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.

to AEP:NRC:6055-12 Page 17 Appendix VIII, Supplement 11 PDI Modification (f) Sizing Specimen (1) The minimum number of flaws shall be ten. (1) The minimum number of flaws shall be ten.

At least 30% of the flaws shall be overlay At least 30% of the flaws shall be overlay fabrication flaws. At least 40% of the flaws shall fabrication flaws. At least 40% of the flaws shall be cracks open to the inside surface. be open to the inside surface. Sizing sets shall contain a distribution of flaw 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.

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

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

2.0 CONDUCT OF PERFORMANCE DEMONSTRATION The specimen inside surface and identification The specimen inside surface and identification shall be concealed from the candidate. All shall be concealed from the candidate. All examinations shall be completed prior to grading examinations shall be completed prior to grading the results and presenting the results to the the results and presenting the results to the candidate. Divulgence of particular specimen candidate. Divulgence of particular specimen results or candidate viewing of unmasked results or candidate viewing of unmasked specimens after the performance demonstration specimens after the performance demonstration is prohibited. is prohibited. The overlay fabrication flaw test and the base metal flaw test may be performed separately.

2.1 Detection Test.

Flawed and unflawed grading units shall be Flawed and unflawed grading units shall be randomly mixed. Although the boundaries of randomly mixed. Although the boundaries of specific grading units shall not be revealed to the specific grading units shall not be revealed to the candidate, the candidate shall be made aware of candidate, the candidate shall be made aware of the type or types of grading units (base or the type or types of grading units (base metal or overlay) that are present for each specimen. overlay fabrication) that are present for each specimen.

to AEP:NRC:6055-12 Page 18 Appendix VIII, Supplement 11 PDI Modification 2.2 Length Sizing Test (d) For flaws in base grading units, the candidate (d) For flaws in base metal grading units, the shall estimate the length of that part of the flaw candidate shall estimate the length of that part of that is in the outer 25% of the base wall the flaw that is in the outer 25% of the base thickness. metal wall thickness.

2.3 Depth Sizing Test.

For the depth sizing test, 80% of the flaws shall (a) The depth sizing test may be conducted be sized at a specific location on the surface of separately or in conjunction with the detection the specimen identified to the candidate. For the test.

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

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

3.0 ACCEPTANCE CRITERIA 3.1 Detection Acceptance Criteria.

Examination procedures, equipment, and a) Examination procedures are qualified for personnel are qualified for detection when the detection when:

results of the performance demonstration satisfy the acceptance criteria of Table VIII-S2-1 for 1) All flaws within the scope of the procedure both detection and false calls. The criteria shall are detected and the results of the performance be satisfied separately by the demonstration demonstration satisfy the acceptance criteria of results for base grading units and for overlay Table VIII-S2-1 for false calls.

grading units.

(a) At least one successful personnel demonstration has been performed meeting the acceptance criteria defined in (b).

to AEP:NRC:6055-12 Pagel9 Appendix VIII, Supplement 11 PDI Modification (b) Examination equipment and personnel are qualified for detection when the results of the performance demonstration satisfy the acceptance criteria of Table VIII-S2-1 for both detection and false calls.

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

3.2 Sizing Acceptance Criteria-(a) The RMS [root mean square] error of the (a) The RMS error of the flaw length flaw length measurements, as compared to the measurements, as compared to the true flaw true flaw lengths, is less than or equal to lengths, is less than or equal to 0.75 inch. The 0.75 inch. The length of base metal cracking is length of base metal flaws is measured at the measured at the 75% through-base-metal 75% through-base-metal position.

position.

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

overlay material by at least 0.1 inch are reported as being intrusions-into the overlay material.

(c) The RMS error of the flaw depth (b) The RMS error of the flaw depth measurements, as compared to the true flaw measurements, as compared to the true flaw depths, is less than or equal to 0.125 inch. depths, is less than or equal to 0.125 inch.

Attachment 2 to AEP:NRC:6055-12 Regulatory Commitments The following table identifies those actions committed to by Indiana Michigan Power Company (I&M) in this document. Any other actions discussed in this submittal represent intended or planned actions by I&M. They are described to the Nuclear Regulatory Commission (NRC) for the NRC's information and are not regulatory commitments.

Commitment Date I&M will complete stress analysis summaries of the preemptive Within 4 weeks after weld overlay prior to restart of Unit 1 and provide the summaries restart of Unit 1 from the within four weeks after restart from the Unit 1 (Fall 2006) Fall 2006 refueling outage.

refueling outage.

I&M will provide the Preemptive Weld Overlay ultrasonic Within 14 days after the examination results to the NRC. completion of the last ultrasonic examination of the weld overlays.