CPSES-200601983, Relief Request B-6 to Unit 1 Inservice Inspection Program Plan from the 1998 Edition of ASME Code, Section XI, Through 2000 Addenda (Interval Start Date - August 13, 2000, Second Interval)

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Relief Request B-6 to Unit 1 Inservice Inspection Program Plan from the 1998 Edition of ASME Code,Section XI, Through 2000 Addenda (Interval Start Date - August 13, 2000, Second Interval)
ML062850255
Person / Time
Site: Comanche Peak Luminant icon.png
Issue date: 10/03/2006
From: Madden F
TXU Power
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
10010, CPSES-200601983, TXX-06154
Download: ML062850255 (30)
v • d • e


Text

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'1141'410ý7 TXU

-. Power TXU Power Mike Blevins Comanche Peak Steam Senior Vice President &

Electric Station Chief Nuclear Officer P. O. Box 1002 (EO1)

Glen Rose, TX 76043 Tel: 254 897 5209 Ref: 10 CFR 50.55a(3)(i)

Fax: 254 897 6652 mike.blevins@txu.com CPSES-200601983 Log # TXX-06154 File# 10010 October 3, 2006 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NO. 50-445 RELIEF REQUEST B-6 TO THE UNIT 1 INSERVICE INSPECTION (ISI) PROGRAM PLAN FROM THE 1998 EDITION OF ASME CODE, SECTION XI, THROUGH 2000 ADDENDA (INTERVAL START DATE - AUGUST 13, 2000, SECOND INTERVAL)

Pursuant to 10 CFR 50.55a(a)(3), TXU Power hereby requests NRC approval of relief from applicable requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, as identified in the attached relief request. This request is for TXU Power's Repair/Replacement program, as established by the ASME Section XI Code, and involves utilization of an alternate approach to ASME Section XI requirements for a particular application.

Approval of this relief request will allow application of full structural weld overlays for nozzle-to-safe end dissimilar metal and safe end-to-piping stainless steel butt welds associated with the pressurizer and connected piping. The overlays are a pre-emptive measure for addressing primary water stress corrosion cracking concerns that have been identified by the industry for welds associated with Alloy 600/82/182 components exposed to pressurized water reactor primary coolant. The proposed alternative requirements to be implemented have been determined to be appropriate for application and examination of the needed overlays, and will provide an acceptable level of quality and safety as required by 10 CFR 50.55a(a)(3)(i).

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway e Comanche Peak e Diablo Canyon

  • Palo Verde e South Texas Project
  • Wolf Creek Aoy /-7

TXX-06154 Page 2 of 2 This communication contains no new licensing basis commitments regarding Comanche Peak Steam Electric Station (CPSES) Unit 1.

TXU Power requests approval of this relief request by January 30, 2007. The approval date was selected to allow time to update procedures prior to the 12 "'

refueling outage for Unit 1, scheduled to start in February of 2007. If you have any questions or need additional information regarding this matter, please feel free to contact Jack Hicks at (254) 897-6725.

Sincerely, TXU Generation Company LP By: TXU Generation Management Company LLC Its General Partner Mike Blevins Y,/A*c;. Madden Director, Oversight and Regulatory Affairs JCH Attachment c- B. S. Mallet, Region IV M. C. Thadani, NRR Resident Inspectors, CPSES T. Parks, Chief Inspector, TDLR

Attachment to TXX-06154 Page 1 of 28 ATTACHMENT 10 CFR 50.55a AUTHORIZATION REQUEST Comanche Peak Unit 1 Proposed Alternative In Accordance With 10 CFR 50.55a(a)(3)(i)

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Attachment to TXX-06154 l

Page 2 of 28 10 CFR 50.55a RELIEF REQUEST 1.0 ASME CODE COMPONENTS AFFECTED Component Numbers: (Pressurizer Vessel)

Comanche Peak Unit I TBX-1-4503-31 (4" spray nozzle-to-safe end weld)

Weld Numbers: TBX-1-4503-30 (4" spray safe end-to-piping weld)

TBX-1-4501-1 (6" safety "1" nozzle-to-safe end weld)

TBX-1-4501-2 (6" safety "1" safe end-to-piping weld)

TBX-1-4501-12 (6" safety "2" nozzle-to-safe end weld)

TBX-1-4501-13 (6" safety "2" safe end-to-piping weld)

TBX-1-4501-23 (6" safety "3" nozzle-to-safe end weld)

TBX-1-4501-24 (6" safety "3" safe end-to-piping weld)

TBX-1-4502-1 (6" relief nozzle-to-safe end weld)

TBX-1-4502-2 (6" relief safe end-to-piping weld)

TBX-1-4500-7 (14" surge nozzle-to-safe end weld)

TBX-1-4500-8 (14" surge safe end-to-piping weld)

Code Class: Class I Examination Categories: B-F Item Number: B5.40

Description:

Alternative Welded Repair for the Pressurizer Safety, Relief, Spray, and Surge Nozzle-to-safe end welds

References:

ASME Section XI, 1998 Edition through the 2000 Addenda ASME Section XI, 1995 Edition, 1996 Addenda ASME Section XI, 2005 Addenda, Nonmandatory Appendix Q ASME Section XI, Code Case N-504-2 ASME Section XI, Code Case N-638-1 ASME Section III, 1971 Edition through Summer 1973 Addenda ASME Section III, 1974 Edition through Summer 1974 Addenda ASME Section III, 1977 Edition through Summer 1979 Addenda 2.0 APPLICABLE CODE EDITION AND ADDENDA ASME Section XI, 1998 Edition through the 2000 Addenda 3.0 APPLICABLE CODE REQUIREMENTS IWA-4420 and IWA-4520(a) of ASME Section XI require repair/replacement activities to be performed and examined in accordance with the Owner's Requirements and the original Construction Code of the component or system. IWA-4430 and IWA-4600 provide for alternative welding methods when the requirements of IWA-4420 cannot be met. Categories B-F and B-J prescribe inservice examination requirements for Class I butt welds.Section XI, Appendix VIII, Supplement 11, as modified in Table 5, specifies the performance demonstration requirements for ultrasonic examination 2

'- Attachment to TXX-06154 Page 3 of 28 ultrasonic examination of weld overlays.

4.0 REASON FOR REQUEST Primary Water Stress Corrosion Cracking (PWSCC) of Alloy 600/82/182 components exposed to Pressurized Water Reactor (PWR) primary coolant has become a growing concern in the nuclear industry over the past decade. In particular, base metal and weld metal components exposed to elevated temperatures, like the pressurizer, have been shown to pose a heightened propensity to PWSCC. As a result, increased inspection requirements have been applied to these locations via several mechanisms, including 10CFR50.55a, the ASME Code, the recently issued NEI 03-08 Mandatory Guidance, "Primary System Piping Butt Weld Inspection & Evaluation Guideline (MRP-1 39)," and internal utility Alloy 600 programs.

Many of these requirements call for dramatically improved ultrasonic examination coverage (>

90% of the inner 1/3t of the dissimilar metal weld) and inspection frequencies far in excess of those required by the existing Inservice Inspection (ISI) program. In many cases, these examination coverage requirements are difficult or impossible to meet using current ultrasonic inspection technology due to the short length of the stainless steel safe end between the dissimilar metal and stainless steel welds and of the nozzle between the dissimilar metal weld and the nozzle transition.

Due to the combination of inspectability issues and a reduced ability to validate the integrity of these welds prior to the observation of leakage, Comanche Peak has concluded that the application of preemptive structural weld overlays to the susceptible pressurizer nozzle locations is the most appropriate course of action to ensure Reactor Coolant System (RCS) pressure boundary integrity and improve future inspectability.

Structural weld overlays have been used for over 20 years for repair and mitigation of intergranular stress corrosion cracking in boiling water reactors and more recently for repair of PWSCC in pressurized water reactors. In some cases, full structural weld overlays have been used to reestablish structural integrity of dissimilar metal (DM) butt welds containing through wall leaking flaws. Full structural weld overlays arrest existing flaws from propagating by favorable residual compressive stresses in the inner portions of the original susceptible welds, provide a PWSCC resistant material, and provide structural reinforcement that meets ASME Code Section XI margins even with existing cracks remaining in the original susceptible welds.

As discussed in this Request, there is no approved comprehensive criterion for Comanche Peak to apply a full structural nickel alloy weld overlay to a DM weld that is constructed of Alloy 82/182 weld material and is believed to be susceptible to or contains PWSCC degradation. Although the ASME Code,Section XI, 1998 Edition through 2000 Addenda Article IWA-4000 is used for the Comanche Peak Repair/Replacement Program, it does not have the needed requirements for this type of weld overlay repair/mitigation. The latest NRC approved ASME Code also does not have the needed requirements for this type of weld overlay. ASME has approved a Code Case (N-740) providing the comprehensive provisions for this type of weld overlay but this Code Case has not yet been approved by the NRC.

Section 3.0 of this Request identifies Code requirements that cannot be met or are not applicable when applying full structural nickel alloy weld overlays as described in this Request. Therefore, in lieu of IWA-4420 (and its referenced original Construction Code for the Pressurizer and attached 3

Attachment to TXX-06154 Page 4 of 28 IWA-4430, IWA-4520(a), IWA-4530, IWA-4600, and the inservice examination requirements of Table IWB-2500-1, alternative requirements are requested for the installation and examination of full structural weld overlays for repairing/mitigating the DM welds and SS welds identified in section 1.0 of this Request. These alternative requirements use methodologies and requirements similar to those in ASME Code Cases N-504-2 and N-638-1. However, as described in section 5.0 of this Request, Cases N-504-2 and N-638-1 cannot be used without modifications.

The Comanche Peak risk-informed ISI Program prescribes inservice examination requirements for Class I butt welds that are used in lieu of the requirements of ASME Section XI Table IWB-2500-1.

However, with this Request, the weld overlays installed on the welds identified in section 1.0 of this Request will be included in either the Augmented or 1SI Program Plan for Comanche Peak Unit 1 and will be examined as described in section 5.0 of this Request. The original DM and SS welds will be removed from the Comanche Peak risk-informed ISI Program.

Pursuant to IOCFR50.55a(a)(3)(i), alternatives are requested on the basis that the proposed alternatives will provide an acceptable level of quality and safety.

5.0 PROPOSED ALTERNATIVE AND BASIS FOR USE A. Proposed Alternative For Application of Weld Overlays Using Modified Code Case N-504-2 A preemptive full structural weld overlay is proposed for each Alloy 82/182 nozzle-to-safe end weld. ASME Code Case N-504-2 allows a flaw to be reduced to an acceptable size through the deposition of weld reinforcement (weld overlay) on the outside surface of the pipe without flaw removal. In this case, the existence of(or lack of) any flaws is not known due to the inability to perform a qualified ultrasonic examination prior to application of the overlays. As such, assumptions are required to be made as to the size and location of flaws which may be present in the original dissimilar metal weld, as discussed below.

Table I identifies the materials of construction for the pressurizer nozzle-to-pipe assemblies within the scope of this relief request. Figure 1 shows the generic configuration of the nozzle-to-pipe assemblies but does not reflect the actual external or internal surface profile. In order that both the dissimilar metal nozzle-to-safe end weld and the stainless steel safe end-to-pipe weld are inspectable per the ASME Code post-overlay, the weld overlays will extend from the carbon steel nozzle to the stainless steel pipe.

Figure 1: Generic Pressurizer Nozzle Configuration Low Alloy Nozzle Weld Overlay SS Alloy' SS 182 Safe Weld Pipe Butter End weld 4

Attachment to TXX-06154 Page 5 of 28 Table I Comanche Peak Unit 1 Pressurizer Nozzle Material Identification Material Identification Nozzle Nozzle-Safe End Weld ID Type NPS Safe End-Pipe Weld ID Nozzle Nozzle-Safe Safe End Safe End- Pipe End Weld Pipe Weld Spray 4" TBX-1-4503-31 SA-508, DM Shop SA-182, SS Field Schedule 160, TBX-1-4503-30 Class 2 Weld Grade Weld SA-376, TP (Alloy F-316L (ER316) 304/TP316 82/182)

Safety 6" TBX-1-4501-1 SA-508, DM Shop SA-182, SS Field Schedule 160, "1" TBX-1-4501-2 Class 2 Weld Grade Weld SA-376-(Alloy F-316L (ER316/ TP304/TP316 82/182) E316L)

Safety 6" TBX-1-4501-12 SA-508, DM Shop SA-182, SS Field Schedule 160, "2" TBX-1-4501-13 Class 2 Weld Grade Weld SA-376-(Alloy F-316L (ER316/ TP304/TP316 82/182) E316L)

Safety 6" TBX-1-4501-23 SA-508, DM Shop SA-182, SS Field Schedule 160, "3" TBX-1-4501-24 Class 2 Weld Grade Weld SA-376-(Alloy F-316L (ER316/ TP304/TP316 82/182) E316L)

Relief 6" TBX-1-4502-1 SA-508, DM Shop SA-182, SS Field Schedule 160, TBX-1-4502-2 Class 2 Weld Grade Weld SA-376-(Alloy F-316L (ER316/ TP304/TP316 82/182) E316L)

Surge 14" TBX-1-4500-7 SA-508, DM Shop SA-182, SS Field Schedule 160, TBX-1-4500-8 Class 2 Weld Grade Weld SA-376, Type (Alloy F-316L (ER308) 316 82/182)

The weld overlay will be designed consistent with the requirements of ASME Code Case N-504-2, "Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping," with the modifications noted in Table 2. The weld overlay will extend around the full circumference of the nozzle to- safe end weld location as required by Code Case N-504-2. The specific thickness and length will be calculated according to the guidance provided in Code Case N-504-2 and Nonmandatory Appendix Q. The design of each overlay will assume that a 3600 circumferential through-wall flaw is present in the original Alloy 82/182 weld.

The determination of the life of the overlay will be based on the size of any indications in the region of the overlay. Fatigue crack growth evaluations will be performed for the dissimilar metal butt welds to demonstrate that the weld overlay thickness is sized adequately to satisfy the requirements in the flaw evaluation procedures of IWB-3640. The initial flaw size assumed in the fatigue crack growth calculations will be consistent with the post-overlay ultrasonic examination requirements (i.e. a minimum of the outer 25% of the original Alloy 82/182 weld will be inspectable post-overlay). If the crack growth analysis shows that a flaw will not grow to the allowable flaw size for the normal ASME Code,Section XI inspection interval, then the existing Code interval will be used for subsequent in-service inspections. If the crack growth analysis shows that the assumed crack will grow to the allowable flaw size, then the in-service inspection interval will be established based on this time. The allowable flaw size will be that flaw size that meets the analytical requirements of Section XI, IWB-3640.

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Attachment to TXX-06154 Page 6 of 28 Preservice inspections, which include the detection and acceptance of welding flaws will be performed in accordance with Code Case N-504-2, Nonmandatory Appendix Q, Subarticle Q-4000, and ASME Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, Supplement 11, as modified by this request.

Code Case N-504-2 is approved for use for austenitic stainless steel material in Regulatory Guide 1.147, Revision 14, provided that it is used with Nonmandatory Appendix Q of the 2005 Addenda of ASME Section XI. An alternate application for nickel-based and carbon materials is proposed due to the configuration of the subject welds, and the lack of an approved code case for these applications. The methodology of Code Case N-504-2 shall be followed with the modifications detailed in Table 2. Details regarding the in-process, pre-service, and inservice examinations that will be applied to the proposed weld overlays are shown in Table 3. These examinations meet all of the requirements of the applicable Codes, as modified by this request.

The above proposed alternative will be implemented during the Comanche Peak Unit 1 1RF 12 Refueling Outage (Spring 2007) and provides an acceptable level of quality and safety.

B. Proposed Alternative For Application of Ambient Temperature Machine GTAW Temper Bead Technique Using Modified Code Case N-638-1 Application of the structural weld overlays will require welding to the carbon steel nozzle material.

The Code of Construction does not permit welding to the carbon steel nozzle without pre-heat or post-weld heat treatment. In lieu of these requirements, the requirements of ASME Code Case N-638-1, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique," will be met, with the modifications detailed in Table 4.

The ambient temperature temper bead welding technique permits application of the structural weld overlay without the need for elevated preheat or post-weld heat treatment required by ASME Section III. The technique has been qualified and will be performed using the methodology described in ASME Code Case N-638-1. Welding will commence when the base materials exhibit a minimum preheat of 50 degrees Fahrenheit. The interpass temperature during weld installation will not be permitted to exceed a maximum value of 350 degrees Fahrenheit. During the welding, heat input will be precisely controlled to conform to the welding procedure specification.

Code Case N-638-1 contains the requirement that a band around the final weld surface be examined using surface and ultrasonic methods. The band is at least 1.5 times the component thickness or 5 inches, whichever is less. The intent of such examinations is to ensure that no adverse effects have impacted the ferritic steel base material as a result of the temper bead welding process. It is conservatively assumed that the ultrasonic (volumetric) examination requirement for the band is the entire base metal below the band. The most likely adverse effect is the potential for delayed hydrogen cracking which would initiate on the same surface of the ferritic steel base material adjacent to the welding. The ultrasonic inspection is to be conducted in accordance with Appendix I of the ASME Code Section XI.

With respect to the weld overlay process on pressurizer nozzle dissimilar metal welds, the Code Case N-638-1 defined band and examination volume would encompass the nozzle base metal volume below the outer diameter nozzle tapered surface and a part of the nozzle outer diameter blend region. Being that the inner diameter of the nozzle cannot be reasonably accessed, these outer diameter surfaces must be used as the ultrasonic test probe scanning surfaces. Such surfaces 6

Attachment to TXX-06154 Page 7 of 28 are not conducive for gaining full coverage of the examination volume due to non-coupling of the ultrasonic test probes over the surface; obstructions causing this non-coupling include the edge of the weld overlay, the transition between the OD nozzle taper and the nozzle outer blend area.

Appendix I of the ASME Code Section XI, 1998 Edition through the 2000 Addenda requires that the ultrasonic examination be conducted in accordance with ASME Code Section V, Article 4 and all supplements of Appendix I except Supplement 9 - Scan Angles. The most applicable examination requirements fall under Article 4 T-440 Vessel Examinations. These requirements include straight beam scanning for laminar and planar reflectors and angle beam scanning for planar reflectors. The straight beam scanning will most likely not detect any delayed hydrogen cracking due to mis-orientation of the cracking with respect to the beam and to the anticipated near surface location of such cracking. Essentially the straight beam is a repeat of the nozzle material examination required by the Construction Code. The angle beam examinations will be largely impacted by the outer diameter surface configuration. To maximize angle beam examination coverage will entail a series of special transducers to be applied even though the most effective angle beam transducers would be those configured to detect near surface breaking planar reflectors. However the most effective NDT method for detection of near surface breaking planar reflectors is not a volumetric method but a surface examination method.

Relief is requested from the ultrasonic test requirements of Code Case N-638-1 because of the limitations in the applicable ultrasonic test techniques (irregular scan surfaces, effectiveness in detecting the most probable flaw mechanism) combined with the increased radiation exposure of inspection personnel in applying such limited techniques. It is noted that surface examinations will be conducted on this band area to ensure that the most probable flaw mechanism is detected.

As such the limited ultrasonic test techniques offer no additional benefit in terms of quality or safety.

Further it is noted that the final weld overlay is to be volumetrically examined using qualified ultrasonic test procedures and personnel in compliance with the Performance Demonstration Initiative (PDI) Supplement 11 qualification program.

Finally it is noted that the pending ASME Section XI, Code Case N-740, which specifically addresses the weld overlay of dissimilar metal welds including the use of the temper bead process on ferritic base material, mandates only a surface examination of the adjacent ferritic base material to the weld overlay (0.5-inch). Ultrasonic examinations are mandated only over the weld overlay surface and underlying weld and adjacent base material volumes. These inspections are consistent with the requested relief.

The nondestructive examination requirements of Code Case N-504-2 and Nonmandatory Appendix Q of the 2005 Addenda of ASME Section XI will be used in lieu of that defined in Code Case N-638-1. Therefore, the NRC condition on use ofN-638-1 is not applicable to this Request and will not be applied.

The above proposed alternative will be implemented during the Comanche Peak Unit 1 1RF12 Refueling Outage (Spring 2007) and provides an acceptable level of quality and safety.

C. Proposed Alternative to ASME Section XI, Appendix VIII, Supplement I I ASME Section XI, 1998 Edition through 2000 Addenda, Appendix VIII, along with Appendix VIII Supplement 11, addresses the requirements for performance demonstration of ultrasonic 7

Attachment to TXX-06154 Page 8 of 28 examination procedures, equipment, and personnel used to detect and size flaws in full structural overlays of wrought austenitic piping welds. Appendix VIII Supplement 11 qualification requirements are modified by the proposed alternatives in the PDI program as indicated in Table 5 because the industry cannot meet the requirements of Appendix VIII, Supplement 11. Therefore, the PDI alternatives to Section XI, Appendix VIII, Supplement 11 as described in Table 5 will be used for qualification of ultrasonic examinations used to detect and size flaws in the full structural weld overlays of this Request.

6.0 DURATION OF THE PROPOSED ALTERNATIVE Use of the proposed alternative is requested for the Comanche Peak Unit 1, second In-Service Inspection (ISI) interval. The resulting repairs are requested for the design life of the repairs, as determined by the required evaluation in Paragraph (g) of Code Case N-504-2 and the corresponding requirements in Nonmandatory Appendix Q.

The installed weld overlay will be added to either the Augmented or ISI Program Plan for Comanche Peak Unit 1 in accordance with Subarticle Q-4300 of Nonmandatory Appendix Q for at least one inservice examination to be completed within the next two refueling outages following installation.

7.0 PRECEDENT Similar 50.55a Requests have been approved by the NRC as noted below:

>- Three Mile Island Nuclear Station, Unit No. I Docket No. 50-289, TAC No. MCI 201, dated July 21, 2004 Authorized relief from flaw removal, heat treatment, nondestructive examination requirements and weld overlay of nozzle-to-safe end weld.

> Calvert Cliffs Nuclear Power Plant, Unit No. 2 Docket No. 50-318, TAC Nos. MC6219 and MC6220, dated July 20, 2005 Authorized use of a weld overlay to repair welds and the Performance Demonstration Initiative (PDI) program for the inspection as alternatives to the ASME Code requirements.

>" Donald C. Cook Nuclear Plant, Unit No. I Docket No. 50-315, TAC No. MC675 1, dated June 27, 2005 Authorized use of PDI Program for weld overlay qualifications in lieu of Supplement II to Appendix VIII of Section XI of the Code

> Millstone Power Station, Unit No. 3 Docket No. 50-423, TAC No. MC8609, dated January 20, 2006 Authorized use of a weld overlay for repair and the Performance Demonstration Initiative (PDI) program for inspection as alternatives to the ASME Code requirements.

> Susquehanna Steam Electric Station Unit 1 Docket No. 50-387, (TAC Nos. MC2450, MC2451 and MC2594), Accession Number ML051220568, dated June 22, 2005 Authorized use of a weld overlay for repair and the Performance Demonstration Initiative (PDI) program for inspection as alternatives to the ASME Code requirements.

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Attachment to TXX-06154 Page 9 of 28 Table 2: Modifications to Code Case N-504-2 and Corresponding Nonmandatory Appendix Q Requirements Code Case N-504-2 and Nonmandatory Appendix Q 4-Modification and Basis Reply: It is the opinion of the Committee that, in lieu of the requirements Modification: Code Case N-504-2 and Section XI Nonmandatory of IWA-4120 in Editions and Addenda up to and including the 1989 Appendix Q in the 2005 Addenda will be used for the application of Edition with the 1990 Addenda, in IWA-4170(b) in the 1989 Edition Alloy 52/52M of the weld overlay of the ferritic (P3) nozzle material, with the 1991 Addenda up to and including the 1995 Edition, and in nickel alloy (F43/P43) weld material, and austenitic stainless steel base IWA-4410 in the 1995 Edition with the 1995 Addenda and later (P8, safe end and pipe) and weld materials, as modified herein.

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

Furthermore, the overlay will be sized to meet all structural requirements without considering the existina Alloy 82/182 and SS welds.

Paragraph (b): Reinforcement weld metal shall be low carbon (0.035% Modification:A nickel alloy, specifically Alloy 52/52M, will be used as max.) austenitic stainless steel applied 360 deg. around the the reinforcement weld metal in lieu of austenitic stainless steel filler circumference of the pipe, and shall be deposited in accordance with a material.

qualified welding procedure specification identified in the Repair Program. Basis: The filler material used will be ERNiCrFe-7A (Alloy 52M, UNS N06054) or ERNiCrFe-7 (Alloy 52, UNS N06052). Repairs, if required, may use Alloy 52, Alloy 52M, or ENiCrFe-7 (Alloy 152, UNS W86152). Alloy 52 and Alloy 152 materials are listed in the ASME Code,Section II and Section IX as F-No. 43 and are acceptable for use under the ASME Code. Alloy 52M is assigned F-No. 43 by ASME per Code Case 2142-2. The requirements of ASME Section III, NB-2400 9

Attachment to TXX-06154 Page 10 of 28 Table 2: Modifications to Code Case N-504-2 and Corresponding Nonmandatory Appendix Q Requirements Code Case N-504-2 and Nonmandatory Appendix Q Modification and Basis will continue to be applied to all filler material as required by ASME Section XI.

The chromium content of Alloys 52/52M/152 is 28-31.5%. Alloy 52M contains higher Niobium content (0.5- 1 %), which improves the weldability of the material and pins the grain boundaries, thus preventing separation between the grains and hot tearing during weld puddle solidification.

These filler materials are selected for their improved resistance to PWSCC. Alloys 52, 52M and 152 all contain about 30% chromium (roughly twice that of Alloy 82/182), imparting excellent corrosion resistance. The existing Alloy 82/182 welds and the Alloy 52/52M overlays are austenitic and have ductile properties and toughness similar to austenitic stainless steel piping welds at PWR operating temperature.

Furthermore, these filler materials are suitable for welding over the ferritic nozzle, Alloy 82/182 weld, and the austenitic stainless steel pipe, welds, and safe ends.

Paragraph(c): Prior to deposition of the weld reinforcement, the surface Modifications: In addition to the provisions in N-504-2 paragraphs (c) to be repaired shall be examined by the liquid penetrant method. and (d), near-surface discontinuities identified by pre-weld overlay Indications greater than 1/ 16 in. are unacceptable and shall be prepared examinations (UT) may be prepared for weld overlay using provisions of for weld reinforcement in accordance with (1) or (2) below: (c) and will be examined using the provisions of(d).

(1) Unacceptable indication shall be excavated to the extent necessary to create a cavity that can be repaired using qualified Basis: Code Case N-504-2 already specifies how to prepare the surface welding procedures. for weld overlay installation and addresses indication identified by (2) One or more layers of weld overlay shall be applied to seal surface examinations. This modification just expands these already unacceptable indications in the area to be repaired without acceptable provisions to near-surface discontinuities that may be excavation. The thickness of these layers shall not be included in identified in the pre-weld overlay UT examinations.

meeting weld reinforcement design thickness requirements.

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Attachment to TXX-06154 Page 11 of 28 Table 2: Modifications to Code Case N-504-2 and Corresponding Nonniandatory Appendix Q Requirements Code Case N-504-2 and Nonmandatory Appendix Q Modification and Basis Paragraph(d): If the preparation of(c)(1) or (c)(2) above is required, the area where the weld reinforcement is to be deposited, including any local repairs or initial weld overlay layers, shall be examined by the liquid penetrant method, and shall contain no indications greater 1/16 in.

prior to the application of the structural layers of the weld overlay.

Paragraph(e): The weld reinforcement shall consist of a minimum of Modification:Delta ferrite (FN) measurements will not be performed two weld layers having as-deposited delta ferrite content of at least 7.5 when using Alloy 52/52M/1 52 filler material. The weld overlay deposit FN. The first layer of weld metal with delta ferrite content of least 7.5 shall meet the following requirements: The austenitic nickel alloy weld FN shall constitute the first layer of the weld reinforcement design overlay shall consist of at least two weld layers deposited from a filler thickness. Alternatively, first layers of at least 5 FN may be acceptable material with a Cr content of at least 28%. The first layer of weld metal based on evaluation. deposited may not be credited toward the required thickness.

Alternatively, a diluted layer may be credited toward the required thickness, provided the portion of the layer over the austenitic base material, austenitic filler material weld and the associated dilution zone from an adjacent ferritic base material contains at least 24% Cr and the Cr content of the deposited weld metal is determined by chemical analysis of the production weld or of a representative coupon taken from a mockup prepared in accordance with the WPS for the production weld.

Basis: Welds composed of Alloy 52/52M/152 are 100% austenitic and contain no delta ferrite due to the high nickel (approximately 60%)

content. The Alloy 52/52M filler material selected for these repairs is fully austenitic and is, therefore, exempt from delta ferrite content requirements. Alternatively, deposit chromium content provides a suitable alternate basis for first layer deposit acceptance in PWSCC resistant structural weld overlays. N-504-2 does not identify first-layer acceptance criteria for fully austenitic deposits, however, draft ASME Code Case N-740 (and its accompanying technical justification) identify 24% chromium as an acceptable measure of first-layer deposit 11

Attachment to TXX-06154 Page 12 of 28 Table 2: Modifications to Code Case N-504-2 and Corresponding Nonmandatory Appendix Q Requirements Code Case N-504-2 and Nonmandatory Appendix Q Modification and Basis acceptability in PWR applications. For structural weld overlay repairs, verification of first layer acceptability will be accomplished using draft N-740 methodology. To accomplish this, first layer overlay deposit chemistry will be verified either by field chemistry measurements or by prior mockup demonstration using comparable welding parameters.

When first-layer surface chemistry meets or exceeds 24% chromium, this initial layer will be credited toward structural overlay deposit thickness. When first-layer surface chemistry chromium is less than 24%

chromium, the first layer will be considered sacrificial and will not be credited toward structural overlay deposit thickness.

Paragraphs (0 and (g) and Q-3000 - Design Considerations Modifications: The provisions of N-504 (f) and (g), Q-3000 in the 2005 Addenda of Section XI, and corrections to Q-3000 to be published in the 2006 Addenda of Section XI will be used.

Basis: ASME Code action BC 05-1530 approved a revision to Appendix Q, which will be published in the 2006 Addenda of ASME Section XI.

The explanation for this revision notes that the action was correcting wording in Nonmandatory Appendix Q, which was first published in the 2005 Addenda. It was approved as part of BC03-1658 as the incorporation of Code Case N-504-2. However, some inadvertent consequences of changed wording during the incorporation of Case N-504-2 created problems in implementation. Therefore, two corrections were approved in the revision to Appendix Q to immediately fix the problems. The correction to Q-3000(b) was to delete the requirement for the design of the overlay to satisfy the requirements of the Construction Code and Owner's requirements. There was no similar wording in Code Case N-504-2. This wording was inappropriate because meeting the requirements of the Construction Code required the absence of cracks. However, the primary purpose of the Appendix and Code Case N-504-2 was to repair cracks with the external weld overlay. The 12

Attachment to TXX-06154 Page 13 of 28 Table 2: Modifications to Code Case N-504-2 and Corresponding Nonmandatory Appendix Q Requirements Code Case N-504-2 and Nonmandator, Appendix Q Modification and Basis appropriate requirements for maintaining Section III (i.e., the Construction Code) limits were properly transferred from Case N-504-2 into Q-3000(b)(1) in the initial issue of Appendix Q and the deletion in Q-3000(b) resolved the problem. Regarding the correction in Q-3000(b)(3), "overlay design thickness" is more appropriate than "pressure design", which is incorrect and was not used in Code Case N-504-2. Overlay design thickness is based on other loads in addition to pressure.

Paragraph (h): The completed repair shall be pressure tested in Modification: In lieu of a hydrostatic test, a system leakage test will be accordance with IWA-5000. If the flaw penetrated the original pressure performed in accordance with Section XI, IWA-5000 in the 2000 boundary prior to welding, or if any evidence of the flaw penetrating the Addenda.

pressure boundary is observed during the welding operation, a system hydrostatic test shall be performed in accordance with IWA-5000. If the Basis: A system hydrostatic test at 1.02 times Class 1 reactor coolant system pressure boundary has not been penetrated, a system leakage, system operating pressure at normal operating temperature (as required inservice, or functional test shall be performed in accordance with IWA- by IWA-5000 and IWB-5000) is of no value. It provides no more 5000. assurance about the structural condition of the weld overlay than the system leakage test performed at Class 1 reactor coolant system operating pressure. ASME Section XI concluded this years ago and eliminated Class I system hydrostatic tests for inservice inspections starting in the 1993 Addenda. ASME Section XI also issued Code Case N-416-1, which was accepted by the NRC, which substituted system leakage tests for system hydrostatic tests following repairs and replacements. ASME Section XI incorporated Code Case N-416-1 into IWA-4540 in the 1999 Addenda allowing a system leakage test to be used in lieu of a system hydrostatic test. A provision of the Code Case and the incorporation of the Case required examinations to be performed as required by ASME Section III because these examinations tell much more about the condition of the repair/replacement activity than any Section XI ressure test. However, the Section III examinations are not 13

Attachment to TXX-06154 Page 14 of 28 Table 2: Modifications to Code Case N-504-2 and Corresponding Nonmandatory Appendix Q Requirements Code Case N-504-2 and Nonmandatory Appendix Q Modification and Basis well suited to the weld overlay configuration. For the application of weld overlays, extensive surface and volumetric examinations of the weld overlay are required by Code Case N-504-2 and Nonmandatory Appendix Q, providing equivalent assurance of the quality of the overlay as the Section III examinations.

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Attachment to TXX-06154 Page 15 of 28 Table 3: Weld Overlay Examination Requirements IN-PROCESS EXAMINATIONS Examination Description Method Technique Reference Acceptance Standards Safe end, welds, nozzle, and pipe pre-overlay Surface Liquid Penetrant N-504-2 and Q-2000 N-504-2, Paragraph (c), Q-surface preparation 2000(b)

Corrective layers of weld metal, if required, Surface Liquid Penetrant N-504-2 and Q-2000 N-504-2, Paragraph (d), Q-not associated with the structural weld 2000(c) overlay Thickness measurement for verifying final Volumetric UT-00L N-504-2 and Q-3000 Per weld overlay design deposited weld reinforcement requirements and Q-3000 PRE-SERVICE EXAMINATION REQUIREMENTS Examination Description Method Technique Reference Acceptance Standards Completed weld overlay for adequate fusion Volumetric 0 UT-0 L; UT angle N-504-2, N-638-1, Q- Per weld overlay design with the base metal and to detect welding beam per PDI- 4100, and Appendix requirements, Q-3000, and flaws. Examination for bonding and welding qualified procedure VIII Q-4100(c) flaws in the portion of the weld overlay installed per Case N-638-1 will occur at least 48 hrs. after the completed weld overlay has returned to ambient temperature.

Examination of the completed weld overlay Surface Liquid Penetrant N-504-2, N-638-1, Q-4100(b) and examination of a band at least 0.50 and Q-4100 inches outward from the toe of the weld overlay around the entire circumference of the nozzle and pipe. For the portion of the weld overlay installed per Code Case N-638-1 and the band area on the nozzle side, this examination will occur at least 48 hrs. after the completed weld overlay has returned to ambient temperature.

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Attachment to TXX-06154 Page 16 of 28 Table 3: Weld Overlay Examination Requirements Completed weld overlay and the outer 25 Volumetric UT angle beam per N-504-2, N-638-I, Q- N-504-2, Paragraph (i) and percent of the original DM weld thickness at PDI-qualified 4200, and Appendix Q-4200 least 0.5- inch beyond the toes of the original procedure VIII DM weld and butter and at least 0.5 inches beyond any as-found flaw. For N-638-1 welding, this examination will occur at least 48 hrs. after the completed weld overlay has returned to ambient temperature.

Completed weld overlay and the outer 25 Volumetric UT angle beam per N-504-2, Q-4200, and N-504-2, Paragraph (i) and percent of the original SS pipe weld PDI-qualified Appendix VIII Q-4200 thickness at least 0.5- inch beyond the toes of procedure the original SS weld and at least 0.5 inches beyond any as-found flaw.

INSERVICE EXAMINATION REQUIREMENTS Examination Description Method Technique Reference Acceptance Standards Full Structural Repair WOL: Weld overlay Volumetric UT angle beam per ASME Section XI Q-4300 and outer 25 percent of the original DM weld PDI procedure Appendix VIII and Q-thickness at least 0.5-inches beyond the toes 4300 of the original DM weld and butter, and at least 0.5 inches beyond any as-found flaw, will be examined within the next two refueling outages. Re-examination will be on a sampling basis in accordance with Q-4300(b) through (f) and Q-43 10. These examinations will be added to the ISI Program Plan in accordance with IWB-2412(b)(1).

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Attachment to TXX-06154 Page 17 of 28 Table 3: Weld Overlay Examination Requirements r r r Full Structural Repair WOL: Weld overlay Volumetric UT angle beam per ASME Section XI Q-4300 and outer 25 percent of the original SS pipe PDI procedure Appendix VIII and Q-weld thickness at least 0.5-inches beyond the 4300 toes of the original SS weld, and at least 0.5 inches beyond any as-found flaw, will be examined within the next two refueling outages. Re-examination will be on a sampling basis in accordance with Q-4300(b) through (f) and Q-4310. These examinations will be added to the ISI Program Plan in accordance with IWB-2412(b)(1).

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Attachment to TXX-06154 Page 18 of 28 Table 4: Modifications to Code Case N-638-1 Code Case N-638-1 Section Modification and Basis Paragraph1.0(a): The maximum area of an individual weld based on Modification: The maximum area of a weld overlay over the ferritic the finished surface shall be 100 sq. in., and the depth of the weld shall nozzle material will be 300 sq. in. The one-half base metal thickness not be greater than one-half of the ferritic base metal thickness. limitation applies only to excavations and repairs, and is not applicable to weld overlays covered by this 50.55a Request.

Basis: The surge line nozzle weld overlay will require welding on more than 100 sq. in. of the surface of the low alloy steel surge nozzle base material. The weld overlays on the remaining nozzles each have less than 100 sq. in. of welding on the surface of the low alloy steel nozzle base material. Extensive experience exists in both BWR and PWR weld overlays applied in excess of the 100 sq. in. limitation. Additionally, industry studies into the qualification of overlays in excess of 100 sq. in.,

have shown no issues with shrinkage stress, weld contraction stresses, etc. A weld overlay repair having 300 sq. in. surface area was recently approved by the NRC in a letter dated June 22, 2005 for Susquehanna Steam Electric Station.

Weld shrinkage caused by application of the overlays will be measured and evaluated for any system impacts, as required by Code Case N-504-2, Paragraph (g)(3).

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Attachment to TXX-06154 Page 19 of 28 Table 4: Modifications to Code Case N-638-1 Code Case N-638-1 Section Modification and Basis Paragraph4.0(b): The final weld surface and the band around the area Modification: In lieu of the ultrasonic examination requirement of defined in para. 1.0(d) shall be examined using a surface and ultrasonic paragraph 4.0(b), the final weld overlay and a one half-inch band around methods when the completed weld has been at ambient temperature for the final weld overlay will be examined in accordance with the at least 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 requirements of Code Case N-504-2 and Nonmandatory Appendix Q at Appendix V.' least 48-hours after the completed overlay has returned to ambient temperature. The results of these examinations will be evaluated in Paragraph1.0(d) (by reference in 4.0(b)): Prior to welding the area to accordance with Appendix Q, Para. Q-4100(b) and Q-4100(c) be welded and a band around the area of at least 1-1/2 times the component thickness or 5 in., whichever is less shall be at least 50'F. Basis: Code Case 638-1 applies to any type of welding where a temper bead technique is to be employed and is not specifically written for a 3 Refer to the 1989 Edition with the 1989 Addenda and later Editions weld overlay repair. However, for a weld overlay, any base material and Addenda. cracking would take place in the HAZ directly below the weld overlay or in the underlying Alloy 82/182 weld deposit and not in the required band of material out beyond the overlay. Therefore, if this cracking were to occur it would be identified by the ultrasonic examination of the weld overlay in accordance with N-504-2 and Appendix Q. The band is not in close proximity to the DM weld and if flaws in the DM weld were to propagate, they would arrest at the interface with the ferritic base material or the Alloy 52/52M/152 weld metal and be contained in the volume of material that is subject to preservice examinations.

Furthermore, in Case N-638-2 ASME has removed the requirement to examine the 1.5 times the component thickness band as no longer necessary to assure acceptability. In addition, the NRC has previously granted relief on this specific issue at Millstone Unit 3 in NRC letter dated Jan. 20, 2006.

With this modification, the NRC Reg. Guide 1.147, Revision 14, condition on use ofN-638-1 is not applicable and will not be applied.

Paragraph4.0(c): Use of weld-attached thermocouples and recording Modification: In lieu of weld-attached thermocounles and recording 19

Attachment to TXX-06154 Page 20 of 28 Table 4: Modifications to Code Case N-638-1 Code Case N-638-1 Section Modification and Basis instruments is not clearly stated but may be implied. When weld- instruments, process temperatures will be monitored with non-attached attached thermocouples are used, the area from which the thermocouples devices, such as contact pyrometers, which will enable manual recording have been removed shall be ground and examined using a surface of process temperatures. Instruments used will be calibrated in examination. accordance with approved calibration and control program requirements.

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Attachment to TXX-06154 Page 21 of 28 Table 5: PDI Program Alternative to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS PDI PROGRAM:

FOR FULL STRUCTURAL OVERLAID WROUGHT The Proposed Alternative to AUSTENITIC PIPING WELDS Supplement 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 three specimens having Alternative: (b)) The specimen set shall consist of at least three different nominal pipe diameters and overlay thicknesses. They shall specimens having different nominal pipe diameters and overlay include the minimum and maximum nominal pipe diameters for which thicknesses. They shall include the minimum and maximum nominal the examination procedure is applicable. Pipe diameters within a range pipe diameters for which the examination procedure is applicable. Pipe of 0.9 to 1.5 times a nominal diameter shall be considered equivalent. If diameters within a range of 0.9 to 1.5 times a nominal diameter shall be the procedure is applicable to pipe diameters of 24 in. or larger, the considered equivalent. If the procedure is applicable to pipe diameters of specimen set must include at least one specimen 24 in. or larger but need 24 in. or larger, the specimen set must include at least one specimen 24 not include the maximum diameter. The specimen set must include at in. or larger but need not include the maximum diameter. The specimen least one specimen with overlay thickness within -0.1 in. to +0.25 in. of set must include at least one specimen with overlay thickness within -0.1 the maximum nominal overlay thickness for which the procedure is in. to +0.25 in. of the maximum nominal overlay thickness for which the applicable, procedure is applicable..

Basis: To avoid confusion, the overlay thickness tolerance contained in the last sentence was reworded and the phrase "and the remainder shall be alternative flaws" was added to the next to last sentence in paragraph 1.1(d)(1).

(d) Flaw Conditions (1) Base metalflaws. All flaws must be cracks in or near the butt weld Alternative: (1) Base metalflaws. All flaws must be cracks in or near the heat-affected zone, open to the inside surface, and extending at least butt weld heat-affected zone, open to the inside surface, and extending at 75% through the base metal wall. Flaws may extend 100% through the least 75% through the base metal wall. Flaws may extend 100% through base metal and into the overlay material; in this case, intentional overlay the base metal and into the overlay material; in this case, intentional fabrication flaws shall not interfere with ultrasonic detection or overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the cracking. Specimens containing IGSCC shall be characterization of the cracking. Specimens containing IGSCC shall be used when available. used when available. At least 70% of the flaws in the detection and 21

Attachment to TXX-06154 Page 22 of 28 Table 5: PDI Program Alternative to Appendix VIII, Supplement 11 sizing tests shall be cracks and the remainder shall be alternative flaws.

Alternative flaw mechanisms, if used, shall 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 paragraph requires that all base metal flaws be cracks.

Implanting a crack requires excavation of the base material on at least one side of the flaw. While this may be satisfactory for ferritic materials, it does not produce a useable axial flaw in austenitic materials because the sound beam, which normally passes only through base material, must now travel through weld material on at least one side, producing an unrealistic flaw response. To resolve this issue, the PDI program revised this paragraph to allow use of alternative flaw mechanisms under controlled conditions. For example, alternative flaws shall be limited to when implantation of cracks precludes obtaining an effective ultrasonic response, flaws shall be semi elliptical with 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 alternative flaws.

To avoid confusion, the overlay thickness tolerance contained in paragraph 1.1 (b) last sentence, was reworded and the phrase "and the remainder shall be alternative flaws" was added to the next to last sentence.

Paragraph 1.1(d)(1) includes the statement that intentional overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the base metal flaws.

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Attachment to TXX-06154 Page 23 of 28 Table 5: PDI Program Alternative to Appendix VIII, Supplement 11 (e) Detection Specimens (1) At least 20% but less than 40% of the flaws shall be oriented within Alternative: (1) At least 20% but less than 40% of the base metal flaws t 200 of the pipe axial direction. The remainder shall be oriented shall be oriented within +/- 20 of the pipe axial direction. The remainder circumferentially. Flaws shall not be open to any surface to which the shall be oriented circumferentially. Flaws shall not be open to any candidate has physical or visual access. The rules of IWA-3300 shall be surface to which the candidate has physical or visual access.

used to determine whether closely spaced flaws should be treated as single or multiple flaws. Basis: The requirement for axially oriented overlay fabrication flaws was excluded from the PDI Program as an improbable scenario. Weld overlays are typically applied using automated GTAW techniques with the filler metal applied in a circumferential direction. Because resultant fabrication induced discontinuities would also be expected to have major dimensions oriented in the circumferential direction axial overlay fabrication flaws are unrealistic.

The requirement for using IWA-3300 for proximity flaw evaluation was excluded, instead indications will be sized based on their individual merits.

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

(a)(1) A base grading unit shall include at least 3 in. of the length of the Alternative: (0)(1) A base metal grading unit includes the overlay overlaid weld. The base grading unit includes the outer 25% of the material and the outer 25% of the original overlaid weld. The base metal overlaid weld and base metal on both sides. The base grading unit shall grading unit shall extend circumferentially for at least I in. and shall not include the inner 75% of the overlaid weld and base metal overlay start at the weld centerline and 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" of the adjacent base material.

Basis: The phrase "and base metal on both sides," was inadvertently included in the description of a base metal grading unit. The PDI program intentionally excludes this requirement because some of the qualification samples include flaws on both sides of the weld. To avoid confusion several instances of the term "cracks" or "cracking" were 23

Attachment to TXX-06154 Page 24 of 28 Table 5: PDI Program Alternative to Appendix VIII, Supplement 11 changed to the term "flaws" because of the use of alternative Flaw mechanisms.

Modified to require that a base metal grading unit include at least 1 in.

of the len h of the overlaid weld, rather than 3 inches.

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

any overlay grading unit.

(a)(3) When a base grading unit is designed to be unflawed, at least I in. Alternative: (a)(3) Sufficient unflawed overlaid weld and base metal of unflawed overlaid weld and base metal shall exist on either side of the shall exist on all sides of the grading unit to preclude interfering base grading unit. The segment of weld length used in one base grading reflections from adjacent flaws.

unit shall not be used in another base grading unit. Base grading units need not be uniformly spaced around the specimen. Modified to require sufficient unflawed overlaid weld and base metal to exist on all sides of the grading unit to preclude interfering reflections from adjacent flaws, rather than the I inch requirement.

(b)(1) An overlay grading unit shall include the overlay material and the Alternative: (b)(I) An overlay fabrication grading unit shall include the base metal-to-overlay interface of at least 6 in'. The overlay grading unit overlay material and the base metal-to-overlay interface for a length of at shall be rectangular, with minimum dimensions of 2 in. least I in.

Modified to define an overlay fabrication grading unit as including the overlay material and the base metal-to-overlay interface for a length of at least 1 in, rather than the 6 in2requirement.

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

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Attachment to TXX-06154 Page 25 of 28 Table 5: PDI Program Alternative to Appendix VIII, Supplement 11 Basis: Paragraph 1.1 (e)(2)(b)(2) states that overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 in. at both ends. rather than around its entire Derimneter.

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

(f) Sizing Specimen (1) The minimum number of flaws shall be ten. At least 30% of the Alternative: (1) The minimum number of flaws shall be ten. At least flaws shall be overlay fabrication flaws. At least 40% of the flaws shall 30% of the flaws shall be overlay fabrication flaws. At least 40% of the be cracks open to the inside surface. flaws shall 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 demonstrations shall be Alternative: (3) Base metal flaws used for length sizing demonstrations oriented circumferentially. shall be oriented circumferentially.

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

2.0 CONDUCT OF PERFORMANCE DEMONSTRATION The specimen inside surface and identification shall be concealed from Alternative: The specimen inside surface and identification shall be the candidate. All examinations shall be completed prior to grading the concealed from the candidate. All examinations shall be completed prior results and presenting the results to the candidate. Divulgence of to grading the results and presenting the results to the candidate.

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

I The overlay fabrication flaw test and the base metal flaw test may be 25

Attachment to TXX-06154

'I Page 26 of 28 Table 5: PDI Program Alternative to Appendix VHI, Supplement 11 performed separately 2.1 Detection Test Flawed and unflawed grading units shall be randomly mixed. Although Alternative: Flawed and unflawed grading units shall be randomly the boundaries of specific grading units shall not be revealed to the mixed. Although the boundaries of specific grading units shall not be candidate, the candidate shall be made aware of the type or types of revealed to the candidate, the candidate shall be made aware of the type grading units (base or overlay) that are present for each specimen. 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 candidate shall estimate the Alternative: (d) For flaws in base grading units, the candidate shall length of that part of the flaw that is in the outer 25% of the base wall estimate the length of that part of the flaw that is in the outer 25% of the thickness. base wall thickness.

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

the remaining flaws, the regions of each specimen containing a flaw to be sized shall be identified to the candidate. The candidate shall (b) When the depth sizing test is conducted in conjunction with the determine the maximum depth of the flaw in each region. detection test and the 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 personnel are qualified for Alternative: Examination procedures are qualified for detection when:

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

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Attachment to TXX-06154 Page 27 of 28 Table 5: PDI Program Alternative to Appendix VIII, Supplement 11

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 VIII-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: The PDI program allows procedure qualification to be performed separately from personnel and equipment qualification. Historical data indicate that, if ultrasonic detection or sizing procedures are thoroughly tested, personnel and equipment using those procedures have a higher probability of successfully passing a qualification test. In an effort to increase this passing rate, PDI has elected to perform procedure qualifications separately in order to assess and modify essential variables that may affect overall system capabilities. For a procedure to be qualified, the PDI program requires three times as many flaws to be detected (or sized) as shown in Supplement 11 for the entire ultrasonic system. The personnel and equipment are still required to meet Supplement 11.

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

(b) All extensions of base metal cracking into the overlay material by at Alternative: This requirement is omitted.

least 0.1 in. are reported as being intrusions into the overlay material.

Basis: The requirement for reporting all extensions of cracking into the overlay is omitted from the PDI Program because it is redundant to the RMS calculations performed in paragraph 3.2(c) and its presence adds 27

Attachment to TXX-06154 Page 28 of 28 Table 5: PDI Program Alternative to Appendix VIII, Supplement 11 confusion and ambiguity to depth sizing as required by paragraph 3.2(c).

This also makes the weld overlay program consistent with the Supplement 2 depth sizing criteria.

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