ML061710464

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

ML061710464
Person / Time
Site:	Cook
Issue date:	06/09/2006
From:	Jensen J Indiana Michigan Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP:NRC:6055-08, TAC MD2119
Download: ML061710464 (18)

Text

Indiana Michigan Power INDIANA Cook Nuclear Plant MICHIGAN One Cook Place pOWERBridgman, MI 49106 P

IýR AERcom A unit of American Electric Power June 9, 2006 AEP:NRC:6055-08 10 CFR 50.55a Docket No.

50-315 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-PI-17 Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Unit 1 PROPOSED ALTERNATIVE TO THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE, SECTION XI REPAIR REQUIREMENTS (TAC No. MD2119)

Reference:

Letter from Joseph N. Jensen, Indiana Michigan Power Company, to Nuclear Regulatory Commission Document Control Desk, "Donald C. Cook Nuclear Plant Unit 2, Proposed Alternative to the American Society of Mechanical Engineeers Code,Section XI Repair Requirements, Request for Additional Information,"

AEP:NRC:6055, Accession Number ML060620063, dated March 1, 2006.

Pursuant to 10 CFR 50.55a(a)(3)(i), Indiana Michigan Power Company (I&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1, is proposing an alternative to the repair requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code).

During the next CNP Unit 1 refueling outage, I&M will be performing full structural preemptive weld overlays on pressurizer nozzle safe end to nozzle welds where NiCrFe Alloy 82/182 was originally used to weld the safe ends thereto. In accordance with 10 CFR 50.55a(a)(2), systems and components of pressurized water-cooled nuclear power reactors must meet the requirements of the ASME Code. I&M is proposing an alternative to the requirements of ASME Code Section XI for overlay welding and nondestructive examination.

The alternative is proposed under the provisions of 10 CFR 50.55a(a)(3)(i), an alternative that provides an acceptable level of quality and safety.

The proposed alternative is provided in the attachment to this letter.

The proposed alternative is similar to the one previously submitted for CNP Unit 2 (referenced letter) and verbally approved by the Nuclejr Regulatory Commission (NRC). The CNP Unit 1 proposed alternative differs from the CNP Unit 2 proposed alternative in that it does not contain a

U. S. Nuclear Regulatory Commission AEP:NRC:6055-08 Page 2 requirement to perform a best effort ultrasonic examination of the 1.5T band, and includes the use of the acceptance criteria of Code Case N-504-2 rather than the ASME Code,Section III, NB-5330 acceptance criteria required by Regulatory Guide 1.147.

The bases for these differences are provided in the attachment to this letter.

In addition to the preceding changes, editorial and CNP Unit 1 specific changes have been incorporated into the proposed alternative. The CNP Unit 1 proposed alternative does not include welds 1-PRZ-23 and 1-RC-9-01F, which were previously overlayed to repair a flaw detected in weld 1-PRZ-23.

The CNP Unit 1 stress and flaw growth analyses required by Code Case N-504-2 (summaries were submitted for CNP Unit 2 at the NRC's request) have not yet been completed. The summaries will be available for NRC review when completed.

I&M requests approval of the proposed alternative by September 8, 2006, to support the CNP Unit 1 outage schedule. There are no new commitments identified in this letter. Should you have any questions, please contact Ms. Susan D. Simpson, Regulatory Affairs Manager, at (269) 466-2428.

Sincerely,

&N.

Jensen Site Support Services Vice President RV/rdw

Attachment:

10 CFR 50.55a Relief Request - ISIR-21, Proposed Alternative for Preemptive Weld Overlays in Accordance with 10 CFR 50.55a(a)(3)(i) c:

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

Attachment to AEP:NRC:6055-08 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. 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 52M1) 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 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 materials, welding parameters, personnel radiation exposure concerns, operational constraints, examination techniques, and procedure requirements.

1 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.

Attachment to AEP:NRC:6055-08 Page 2 2.0 ASME CODE COMPONENTS AFFECTED Code Class:

Code

References:

Examination Categories:

Item Numbers:

==

Description:==

Component Number:

Class 1 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)

ASME Code Case N-638-1 (Temper Bead Welding)

B-F and B-J B5.40 and B9.11 PWOLs for PRZ Spray, Safety, Relief and Surge Nozzle Safe End to Nozzle DMWs and PWOLs for the Elbow to Safe End Welds 1-PRZ-20 1-PRZ-21 1-PRZ-22 1-PRZ-24 I -PRZ-25 1-RC-5-05F 1-RC-6-OIF 1-RC-7-01F 1-RC-8-01F 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 III, 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."

Attachment to AEP:NRC:6055-08 Page 3 4.0 APPLICABLE CODE REQUIREMENTS FOR WHICH RELIEF IS REQUESTED

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

2. NRC conditionally approved Code Case N-638-1 with the condition as specified in Regulatory Guide (RG) 1.147 Revision 14.

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 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 in accordance with ASME Code Case N-638-1 (Reference 2) with the modifications proposed in Table 2. The 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 Susqhehanna, LLC's Susqhehanna Steam Electric Station, Unit 1 (Reference 7); and Dominion

Attachment to AEP:NRC:6055-08 Page 4 Nuclear Connecticut's Millstone Power Station, Unit 3 (Reference 8).

These requests were associated with welding over detected flaws outside the acceptance criteria of Section X1.

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 modifications to ASME Code Cases N-504-2 and N-638-1 and the use of PDI provide an acceptable level of quality and safety in accordance with the requirements of 10 CFR 10.55a(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 ('IMI-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, "Susqhehanna 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

Attachment to AEP:NRC:6055-08 Page 5 Requirements (TAC Nos. MC2450, MC2451 and MC2594)," Accession Number ML051220568, dated June 22, 2005.

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) Accession Number ML053260012.

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 Engineeers 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 to AEP:NRC:6055-08 Page 6 SS

) End (SA-182 F316L)

ýozzle Weld RootIA182 Balance

-Carbon Steel Nozzle (SA-216 Grade WCC)

Figure 1 -Typical PWOL Configuration

Attachment to AEP:NRC:6055-08 Page 7 TABLE 1 DESIGN/MATERIAL/NONDESTRUCTIVE EXAMINATION Modifications to Code Case N-504-2 and ASME Section XI, Appendix Q Code Case N-504-2 and ASME Section XI Appendix Q Proposed Modifications (b) Reinforcement weld metal shall be low carbon (0.035%

[percent]

maximum) austenitic stainless steel applied 360 degrees around the circumference of the pipe, and shall be deposited in accordance with a qualified welding procedure specification identified in the Repair Program [essentially same as Q-2000(a)].

IModification: Weld overlay filler metal shall be an austenitic nickel alloy (28%

Cr minimum) applied 360 degrees around the circumference of the item, and shall be deposited using a

Welding Procedure Specification for groove welding, qualified in accordance with the Construction Code and 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 minimum of two weld layers having as-deposited delta ferrite content of at least 7.5 FN. The first layer of weld metal with delta ferrite content of at least 7.5 FN shall constitute the first layer of the weld reinforcement design thickness. Alternatively, first layers of at least 5 FN may be acceptable based on evaluation

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

Modification:

There is no requirement for delta ferrite, and delta ferrite measurements will not be performed for this overlay.

Basis: The deposited Alloy 52 or Alloy 52M weld metal is 100% austenitic and contains no delta ferrite due to the high nickel composition (approximately 60% nickel).

(h) The completed repair shall be pressure tested in accordance with IWA-5000. If the flaw penetrated the original pressure boundary prior to welding, or if any evidence of the flaw penetrating the pressure boundary is observed during the welding operation, a system hydrostatic test shall be performed in accordance with IWA-5000.

If the system pressure boundary has not been penetrated, a system leakage, inservice, or functional test shall be performed in accordance with IWA-5000.

Modification: In lieu of hydrostatic testing, a system leakage test and a UT of the weld overlay shall be performed in accordance with the Third Interval ISI Program and ASME Code Case N-416-1.

Basis: Code Case N-416-1 has been approved for use at CNP as an alternative to hydrostatic testing (Reference 10).

Attachment to AEP:NRC:6055-08 Page 8 TABLE 2 AMBIENT TEMPERATURE TEMPER BEAD WELDING Modifications To Code Case N-638-1 Code Case N-638-1 Proposed Modifications 1.0 GENERAL REQUIREMENTS (a) The maximum area of an individual weld Modification:

The maximum area of an based on the finished surface shall be individual weld based on the finished surface 100 square inches, and the depth of the weld over the ferritic material shall be 300 square shall not be greater than one-half of the inches.

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 Susqueharma 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, full UT of the around the area defined in paragraph 1.0(d) 1.5T 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

Attachment to AEP:NRC:6055-08 Page 9 Code Case N-638-1 Proposed Modifications 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The ultrasonic examination shall be in accordance with Appendix I.

perform a meaningful UT of the required band of base material because of the existing nozzle configuration shown in Figure 1. This Code Case applies to any type of welding where a temper bead tectnique 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.

The UT examination of the PWOL (welded region) and dye penetrant examination of both the weld and 1.5T band on the ferritic steel nozzle is sufficient to verify that defects have not been induced in the ferritic carbon steel nozzle material due to the welding process.

Attachment to AEP:NRC:6055-08 Page 10 Code Case N-638-1 Proposed Modifications Regulatory Guide (RG) 1.147 requires the use of ASME Boiler and Pressure Vessel Code, Section Ill, NB-5330 acceptance criteria for Code Case N-638-1.

Modification:

I&M will use the acceptance criteria in Code Case N-504-2 in lieu of the RG restriction.

Basis: The context of the original Code Case N-638 was to perform repair welds in vessels and other heavy wall components. The PWOL is a different application of the ambient temperature temper bead welding and has applicable acceptance criterion given in Code Case N-504-2.

Attachment to AEP:NRC:6055-08 Page I11 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:

Attachment to AEP:NRC:6055-08 Page 12 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.

Attachment to AEP:NRC:6055-08 Page 13 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 (b)(3) Detection sets shall be selected from Table VIII-S2-1.

The minimum detection Table VIII-S2-1.

The minimum detection sample set is five flawed base grading units, ten sample set is five flawed base metal grading unflawed base grading units, five flawed overlay units, ten unflawed base metal grading units, five grading units, and ten unflawed overlay grading flawed overlay fabrication grading units, and ten units. For each type of grading unit, the set shall unflawed overlay fabrication grading units. For contain at least twice as many unflawed as each type of grading unit, the set shall contain at flawed grading 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 I personnel qualification set is required.

Attachment to AEP:NRC:6055-08 Page 14 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.

Attachment to AEP:NRC:6055-08 Page 15 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).

Attachment to AEP:NRC:6055-08 Page 16 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), (b) shall be satisfied separately by the demonstration results for base metal grading units and for overlay fabrication grading units.

3.2 Sizina 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.