Text

Alternative Request RR-04-20, Use of Weld Overlays as an Alternative Repair and Mitigation Technique
	ML14112A071
Person / Time
Site:	Millstone
Issue date:	04/11/2014
From:	Mark D. Sartain; Dominion Nuclear Connecticut
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	14-114
	Download: ML14112A071 (32)
	v • d • e

Dominion Nuclear Connecticut, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 PrDominione Web Address: www.dom.com April 11, 2014 U. S. Nuclear Regulatory Commission Serial No.14-114 Attention: Document Control Desk NSSL/MLC RO Washington, DC 20555 Docket No.

50-336 License No.

DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 2 ALTERNATIVE REQUEST RR-04-20, USE OF WELD OVERLAYS AS AN ALTERNATIVE REPAIR AND MITIGATION TECHNIQUE Pursuant to 10 CFR 50.55a(a)(3)(i), Dominion Nuclear Connecticut, Inc. (DNC) requests approval of proposed alternatives to the requirements of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code) for certain repair/replacement activities.

These repair/replacement activities are related to application of repair/mitigative weld overlays to address the potential for primary water stress corrosion cracking (PWSCC) of dissimilar metal welds (DMW) in Class 1, 2 and 3 items. As described in the attachment to this letter, DNC is proposing to mitigate the potential for PWSCC of the selected DMWs by application of a full structural weld overlay.

This approach provides an alternative to inspection alone as a means to assure structural integrity of the affected components.

During the third 10-year ISI interval at MPS2, DNC received approval to perform weld overlays on several dissimilar and similar metal welds, including the two welds that are the subject of this alternative request (References 1 and 2). Because no degradation was detected during the examination of these two welds at that time, weld overlays were not performed and that portion of the alternative request was never implemented.

MPS2 is currently in its fourth 10-year ISI interval, which began on April 1, 2010.

Consequently, DNC is resubmitting an alternative request for the subject welds. The alternative requirements of this request will be applied for the duration of the fourth 10-year ISI interval.

Approval of the proposed alternatives is requested by April 15, 2015 to support planned activities for the fall 2015 refueling outage.

If you have any questions in regard to this submittal, please contact Wanda Craft at (804) 273-4687.

Sincerely, Mark D. Sartain Vice President - Nuclear Engineering

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7

Serial No.14-114 Docket No. 50-336 Page 2 of 2 Commitments made in this letter: See Attachment 2 Attachments:

1) Alternative Request RR-04-20, Use of Weld Overlays as an Alternative Repair and Mitigation Technique with Enclosures 1 and 2

2) Commitment Summary

References:

1) NRC Letter "Millstone Power Station, Unit No. 2 - Relief Request RR-89-61 Regarding the Use of Weld Overlays as an Alternative Repair and Mitigation Technique (TAC No. MD6965,) dated May 8, 2008 (ADAMS Accession No. ML081150692).

2) NRC Letter "Millstone Power Station, Unit No. 2 - Relief Request RR-89-61, Revision 2, Regarding the Use of Weld Overlays as an Alternative Repair (TAC No.

ME1765),"

dated October 15, 2009 (ADAMS Accession No.'

ML092870739).

cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 M. C. Thadani Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 B 1 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.14-114 Docket No. 50-336 ATTACHMENT I WITH ENCLOSURES 1 AND 2 ALTERNATIVE REQUEST RR-04-20 USE OF WELD OVERLAYS AS AN ALTERNATIVE REPAIR AND MITIGATION TECHNIQUE MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.14-114 Docket No. 50-336, Page 1 of 9 Table of Contents 1.0 ASME Code Components Affected...................................................................

2 2.0 Applicable Code Edition and Addenda............................................................

2 3.0 Applicable Code Requirement.........................................................................

3 4.0 Reason for the Request...................................................................................

3 5.0 Proposed Alternatives and Supporting Information..........................

4 6.0 Duration of the Proposed Request...................................................................

8 7.0 P re ce d e nts................................................................................................

.... 8 8.0 R efe rences................................................................................................

..... 8 9.0 C onclusion................................................................................................

..... 9 - Figures Figure 1 -Typical Weld Overlay Configuration...........................................................

5 - Tables Table 1 - 2R23 Welds Affected by This Alternative..............................

2 Table 2 - Materials and Configurations for All Welds Affected by This Alternative....... 4 Alternative Requirements for Dissimilar Metal Weld Overlays.......................... 7 pages - Figures Fig. 1 Examination Volume and Thickness Definitions..................................... 6 Table 1 Modifications to ASME Code Section Xl, Appendix VIII, Supplement 11 for the Use of Alternative Request RR-04-20................................

9 pages

Serial No.14-114 Docket No. 50-336, Page 2 of 9 ALTERNATIVE REQUEST RR-04-20 USE OF WELD OVERLAYS AS AN ALTERNATIVE REPAIR AND MITIGATION TECHNIQUE Proposed Alternative In Accordance with 10 CFR 50.55a(a)(3)(i)

- Alternative Provides Acceptable Level Of Quality And Safety -

1.0 American Society of Mechanical Engineers (ASME) Code Components Affected ASME Code Class:

Reference:

Code Class 1 ASME Code, Section Xl, IWA-4000 Examination Category: Not applicable Item Number:

==

Description:==

Components:

Code Case N-722-1, Item Nos. B15.210 and B15.215 Code Case N-770-1, Inspection Item A-2 and B Class 1 piping dissimilar metal welds with Alloy 82/182 weld material susceptible to primary water stress corrosion cracking Millstone Power Station Unit 2 (MPS2) 2-inch nominal pipe size (NPS) reactor coolant system (RCS) hot leg drain line welds and cold leg letdown line welds Table 1 edAdjacent.SS safe.-

Nozzle-to-safe-end nd-toelbow opie

.end-to-elbow, or pipe Welds weld 2-inch NPS RCS Hot Leg Drain Line Welds BPD-C-1001 I

BPD-C-1 003 2-inch NPS RCS Cold Leg Letdown Line Welds BPD-C-4000 BPD-C-4002

2.0 Applicable Code Edition and Addenda

ASME Code,Section XI, 2004 Edition (No Addenda).

Serial No.14-114 Docket No. 50-336, Page 3 of 9

3.0 Applicable Code Requirements

ASME Code,Section XI, 2004 Edition, No Addenda, IWA-4000 ASME Code,Section XI, 2001 Edition, No Addenda, Appendix VIII, Supplement 11 (Reference 8.7)

ASME Code, Section Xl, 2001 Edition, No Addenda, Appendix VIII, Supplement 10 (Reference 8.6) is used for UT examination PDI requirements for DMWs including the limitation in 10 CFR 50.55a(b)

ASME Code Case N-722-1 ASME Code Case N-770-1

4.0 Reason for Request

Dissimilar metal welds (DMWs) containing nickel welding alloys 82 and 182 have experienced primary water stress corrosion cracking (PWSCC) in components operating at pressurized water reactor temperatures.

Dominion Nuclear Connecticut, Inc (DNC) proposes to mitigate the primary water stress corrosion cracking susceptibility of the MPS2, 2-inch NPS hot leg drain and 2-inch NPS cold leg letdown line dissimilar metal welds (DMW) by installing a full structural weld overlay (FSWOL) on each of the DMWs.

This approach provides an alternative to inspection alone as a means to assure the structural integrity of these locations.

These welds were last -ultrasonically examined in accordance with ASME Section Xl, Appendix VIII requirements in fall 2009.

No flaws were detected during those examinations. These welds are scheduled for reexamination during the spring 2014 refueling outage.

During the fall 2015 refueling outage, DNC will perform an ASME Code Section Xl ultrasonic examination (UT) of the DMWs only after application of the FSWOLs.

Currently, there are no generically accepted criteria for a licensee to apply a FSWOL to Alloy 82/182 weld material. The issue and addenda of ASME Code Section Xl applicable to MPS2 does not contain requirements for weld overlays. This request proposes to use the guidance of ASME Code Case N-504-4, with clarifications specified in Revision 16 of NRC Regulatory Guide 1.147 as well as guidance contained in ASME Code Cases N-740 and N-740-1, which includes criteria for WOL repairs using austenitic nickel based materials. Additionally, Appendix VIII of ASME, Section Xl cannot be used directly for nondestructive examination (NDE) of a structural weld overlay repair. Therefore, an alternative is proposed to use the Performance Demonstration Initiative (PDI) program implementation of Appendix VIII, for use with alternative request RR-04-20. A detailed comparison of Appendix VIII, Supplement 11 and PDI requirements is provided in, Enclosure 2.

Serial No.14-114 Docket No. 50-336, Page 4 of 9 This request describes the requirements DNC proposes to use to design and install FSWOLs on the DMWs referenced.

5.0 Proposed Alternatives and Supporting Information 5.1 Component Descriptions and Materials Two nozzles with DMWs are scheduled to have FSWOLs applied during the fall 2015 refueling outage (2R23). These nozzle welds and adjacent stainless steel (SS) safe-end-to-elbow or pipe welds are 2-inch NPS RCS hot leg drain line welds and cold leg letdown line welds.

The materials and configuration descriptions for the two nozzles scheduled for FSWOL in 2R23 are described in Table 2 below.

Table 2: Materials and Configurations for the Welds Affected by This Alternative Nozzle-to-Adjacent SS.Safe-Nozzle-to-Safe-End Welds Materials End-to-Elbow or Pipe Materials Welds 2-inch NPS RCS Hot Leg Drain And Cold Leg Letdown Line Welds Nozzle is (P-No. 1)

Safe End is (P-No. 8)

Carbon Steel, A 105 SS SA 182 BPD-C-1001 GR II, BPD-C-1003 TYPE 316, BPD-C-4000 Weld and Butter are BPD-C-4002 Weld is SS Type 316, Alloy 82/1 82, and Pipe is (P-No. 8)

Safe End is (P-No. 8) SS SS A-376 Type 316 SA 182 TYPE 316 5.2 Proposed Alternatives Information DNC is proposing to use the alternative requirements submitted in Enclosure 1. The proposed alternative requirements are the result of industry operating experience (OE) pertaining to the application of FSWOLs. This includes FSWOLs for flaws suspected or confirmed to be from PWSCC, and for FSWOLs which are being directly applied to DMWs with both austenitic stainless steel Type 308 or 309 and austenitic nickel based Alloy 52M weld material.

For the scheduled FSWOLs, the proposed alternative request also applies adjacent stainless steel safe-end-to-pipe or safe-end-to-elbow welds identified in 1 and 2. The general configuration of a typical WOL is depicted in Figure 1 section.

to the Tables of this

Serial No.14-114 Docket No. 50-336, Page 5 of 9 A FSWOL can be applied in a manner that will allow these welds to be examined following the application of the WOL. This examination can be accomplished using the Performance Demonstration Initiative (PDI) and the alternatives to ASME Code Section Xl, Appendix VIII, Supplement 11 (Reference 8.7) described in Enclosure 2, Table 1 of this request and supplemented by the alternative requirements in Enclosure 1 that address FSWOL design.

The proposed alternative requirements of this request would be applied for the duration of the current fourth 10-year ISI interval.

5.3 The Structural Weld Overlay Assembly The ferritic material of the nozzles is P-No. 1. The material of the safe ends and elbows is wrought SS (P-No. 8). The pipe material is wrought SS (P-No. 8). The existing weld filler material for the PWSCC susceptible welds is Alloy 82/182 (F-No. 43 which is equivalent to P-No. 43).

The FSWOL replaces the structural design requirements of the pipe as if the pipe were not there. As shown in Figure 1 of this section, this WOL (weld reinforcement) will completely cover the existing Alloy 82/182 weld metal and will extend onto the ferritic and austenitic SS material on each end of the DMW, including the adjacent SS weld.

For each weld, a FSWOL, designed for the worst case flaw, will be applied in accordance with the proposed alternative requirements in Enclosure 1 with a UT examination following the application of the WOL.

Existing Features P ip e o r I I O E lb o w (CSS) or (SS)

SE/Pipe or SE/Elbow

.l

.z e - - W =..........

</-

Safe End (OSS)_or (SS)1 Structural Nozzle/SE Weld Overlay~~~~

.ed--

A 212 Overlay Weld (A82/182)

(A52/152)

\\

W t

/ II k........... e l B u tte rin g l (A82/182)

___[ l Ferritic Steel

'Nozzle Figure 1 -Typical Weld Overlay Configuration

Serial No.14-114 Docket No. 50-336, Page 6 of 9 5.4 Weld Overlay Design The FSWOLs will be designed assuming the worst case flaw, in accordance with Section 2.0 of the proposed alternative requirements of Enclosure 1. The FSWOLs that will be applied to the DMWs at MPS2 will be designed for the remaining plant life.

Westinghouse report WCAP-16896, Rev. 2 (Reference 8.8) provides the technical basis for application of the FSWOL at MPS2. The report also describes the geometries of the FSWOL, summarizes the associated analyses, and provides the methodology used to demonstrate the acceptability of the FSWOL design qualifications. Proprietary and non-proprietary versions of WCAP-16896, Rev. 2 were submitted to the NRC on July 23, 2009 (Reference 8.9) in support of NRC's review and approval of RR-89-61, Revision 2.

WCAP-16896 Rev. 2, addressed the requirements of ASME Section Xl, Code Case N-740 which has since been revised. A review of the WCAP against the requirements of Code Case N740-2 was performed by Westinghouse to verify the continued validity of the technical basis for the design of the proposed FSWOLs. Westinghouse determined that the revisions to the referenced Code Case do not impact the technical basis provided in WCAP-16896 Rev. 2 (Ref. 8.8).

5.5 Examinations For the FSWOLs, UT examinations of completed WOLs will be performed to meet the proposed alternative requirements of Enclosure 1. In addition, the UT examination of a completed FSWOL will be performed in accordance with ASME Code Section XI, 2001 Edition, No Addenda, Appendix VIII, Supplement 11 (Reference 8.7) with the alternatives that are used to comply with the PDI program, as described in Enclosure 2.

5.5.1 Required Activities DNC will provide the following information within 14 days following the completion of the UT examination of the FSWOL installations:

(A) A report of the weld overlay examination results will be provided that includes a listing of indications detected.

The recording criteria of the ultrasonic examination procedure to be used for the examination of the overlays requires that the indications, regardless of amplitude, be investigated to the extent necessary to provide accurate characterization, identity, and location.

Additionally, the procedure requires that the indications, regardless of amplitude, that cannot be clearly attributed to the geometry of the overlay configuration be considered flaw indications.

(B)

A report documenting the disposition of indications using the standards of ASME Section Xl, IWB-3514-2 and/or IWB-3514-3 criteria will be provided and, if possible, the type and nature of the indications. The UT examination procedure requires that suspected flaw indications are to be plotted on a

Serial No.14-114 Docket No. 50-336, Page 7 of 9 cross-sectional drawing of the weld and that the plots should accurately identify the specific origin of the reflector.

(C) A report will be provided discussing any repairs to the weld overlay material and/or base metal and the reason for the repairs.

A preliminary report, prior to entry into Mode 4 following completion of the weld overlays, and a final evaluation within 60 days of the plant restart will be submitted.

DNC will provide the results of evaluations that are described in Paragraphs g(2) and g(3) of Code Case N-504-4, which require evaluations of residual stresses and flaw growth of the repaired welds.

The effects of any changes in applied loads as a result of weld shrinkage from the entire overlay on other items in the piping system shall be evaluated.

The analysis will be performed to confirm that the requirements of sub articles NB-3200 and NB-3600 of the ASME Code,Section III are satisfied.

The analysis includes the crack growth calculations to demonstrate that crack growth in the weld overlay or base metal is acceptable and residual stress distribution in the weld overlay and original weld demonstrate favorable stress distribution.

5.6 Hot Cracking Industry OE exists for hot cracking in the first layer of nickel alloy WOL deposits over SS base materials. This concern is alleviated by applying austenitic stainless steel weld metal over the SS base materials included in the WOL. MPS2 will not credit this first layer of weld metal as part of the structural design thickness of the weld overlay.

5.7 Discussion on Acceptable Level of Quality or Safety or Hardship Without A Compensating Increase in the Level of Quality or Safety The use of the alternatives proposed in this request for the design of FSWOLs applied as either a repair or mitigative WOL will result in an acceptable level of quality and safety for the following reasons:

a FSWOL design does not take credit for the original DMW or SS weld and replaces the structural design requirements of the pipe, as if the pipe were not there; the material used in the FSWOL is Alloy 52M filler material, which is resistant to PWSCC; the compressive stress created by the FSWOL in the underlying base material should prevent or minimize the growth of existing flaws.

Serial No.14-114 Docket No. 50-336, Page 8 of 9 6.0 DURATION OF THE PROPOSED REQUEST This request will be applied for the remainder of the current MPS2 fourth 10-year ISI interval, which is scheduled to end on March 31, 2020.

7.0 PRECEDENTS A similar alternative request, RR-89-61, Rev. 2, was approved for use at MPS2 on October 15, 2009 (ADAMS Accession No. ML092870739).

Additionally, similar alternative/relief requests for FSWOLs of dissimilar metal weld (both PWR and BWR) have been approved by the NRC for a number of nuclear power plants throughout the industry citing similar proposed relief request methodology.

These alternative/relief requests were associated with welding over detected or postulated flaws outside the acceptance criteria of Section Xl using proposed modifications to existing Code Cases N-504 and N-638 and NRC conditions for use.

8.0 REFERENCES

8.1 ASME Code, Section Xl, 2004 Edition, No Addenda, IWA-4000.

8.2 U.S. NRC, Regulatory Guide 1.147, Revision 16, "Inservice Inspection Code Case Acceptability, ASME Section Xl, Division1, October 2010.

8.3 ASME Code Case N-504-4, Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping, Section Xl, Division 1, July 14, 2006.

8.4 Not used.

8.5 ASME Code Case N-740, N-740-1 and N-740-2, Full Structural Dissimilar Metal Weld Overlay for Repair or Mitigation of Class 1, 2, and 3 Items, Section Xl, Division 1, November 10, 2008 8.6 ASME Code, Section Xl, 2001 Edition, No Addenda, Appendix VIII, Supplement 10.

8.7 ASME Code,Section XI, 2001 Edition, No Addenda, Appendix VIII, Supplement 11.

8.8 Westinghouse report WCAP-16896, "Millstone Unit 2 RCS Surge, Spray Shutdown Cooling, Safety Injection, Charging Inlet, and Letdown/Drain Nozzles Structural Weld Overlay Qualification," Rev. 2, dated June 2009.

Serial No.14-114 Docket No. 50-336, Page 9 of 9 8.9 DNC Letter 09-376, Millstone Power Station Unit 2, Request RR-89-61, Revision 2, Alternative Repair and Mitigation Requirements for Structural Weld Overlays, dated July 23, 2009 (ADAMS Accession No. ML092090215).

8.10 Westinghouse Letter LTR-MRCDA-14-1 1, Rev. 1, "Applicability Review of Current Millstone Unit 2 Drain Nozzle SWOL Documents," dated February 19, 2014.

8.11 NRC letter, H. K.Chernoff to D. A. Heacock, Millstone Power Station, Unit No. 2 -

Relief Request RR-89-61, Revision 2, Regarding the Use of Weld Overlays as an Alternative Repair (TAC NO. ME1765), dated October 15, 2009.

9.0 CONCLUSION

The NRC has approved similar alternative requests to support application of repair and mitigative WOLs to DMWs made with Alloy 82/182 weld material. The alternatives to existing ASME Code requirements that are provided in this request include consideration of available OE derived from a review of other similar requests. Additionally, NRC has previously reviewed and approved the application of FSWOLs for the components described in this application (References 8.9 and 8.11).

Consistent with the requirements of 10 CFR 50.55a(a)(3)(i), DNC has demonstrated that the use of the alternatives described in this request for the design of FSWOLs applied as either a repair or a mitigative WOL will result in an acceptable level of quality and safety.

Serial No.14-114 Docket No. 50-336 ATTACHMENT 1 ENCLOSURE 1 ALTERNATIVE REQUIREMENTS FOR DISSIMILAR METAL WELD OVERLAYS FOR THE USE OF ALTERNATIVE REQUEST RR-04-20 MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.14-114 Docket No. 50-336, Enclosure 1, Page 1 of 7 ALTERNATIVE REQUIREMENTS FOR DISSIMILAR METAL WELD OVERLAYS FOR THE USE OF ALTERNATIVE REQUEST RR-04-20 In lieu of the requirements of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code)Section XI, IWA-4410 and IWA-461 1, a defect in austenitic stainless steel or austenitic nickel alloy piping, components, or associated welds may be reduced to a flaw of acceptable size in accordance with IWB-3640 by addition of a repair weld overlay.

In addition, for these materials, in lieu of the requirements of IWA-4410, a mitigative weld overlay may be applied.

Section Xl references are to the 2004 Edition, No Addenda. The weld overlay shall be applied by deposition of weld reinforcement (weld overlay) on the outside surface of the piping, component, or associated weld, including ferritic materials when necessary, provided the following requirements are met:

1) GENERAL REQUIREMENTS Full Structural Weld Overlay -

Deposition of weld reinforcement on the outside diameter of the piping, component, or associated weld, such that the weld reinforcement is capable of supporting the design loads, without consideration of the piping, component, or associated weld beneath the weld reinforcement.

Full structural weld overlay can either be a mitigative or repair weld overlay as defined below:

Mitigative Weld Overlay - Weld overlay that is applied over material with no inside surface planar defects, prior to the weld overlay being applied.

Repair Weld Overlay - Weld overlay that is applied over material with a defect, or where a pre-weld overlay exam is not performed.

(a) A full-structural weld overlay shall be applied by deposition of weld reinforcement (weld overlay) on the outside surface of circumferential welds between items, inclusive of the UNS N06082 or W86182 welds that join the two items. The design of the overlay may be extended to include the adjacent stainless steel to stainless steel welds (P-No. 8 to P-No. 8).

(b) This alternative applies to dissimilar metal welds between P-No. 8 or 43 and P-No. 1 materials. This alternative also applies to dissimilar metal welds between P-No. 8 and P-No. 43 materials joined with austenitic F-No. 43 filler metal, and to welds between P-No. 8 and P-No. 8 materials as described in 1(a).

(c) Weld overlay filler metal shall be nickel alloy (28% Cr min., ERNiCrFe-7 or ERNiCrFe-7A) meeting the requirements of (e) below applied 360 degrees around the circumference of the item and deposited using a Welding Procedure Specification (WPS) for groove welding, qualified in accordance with the Construction Code and Owner's Requirements and identified in the Repair/Replacement Plan.

Serial No.14-114 Docket No. 50-336, Enclosure 1, Page 2 of 7 (d) Prior to deposition of the weld overlay, the surface to be weld overlaid shall be examined using the liquid penetrant method.

Indications with major dimensions greater than 1/16 in. (1.5 mm) shall be removed, reduced in size, or weld repaired in accordance with the following requirements:

(1) For weld repair, one or more layers of weld metal shall be applied to seal unacceptable indications in the area to be repaired with or without excavation.

The thickness of these layers shall not be used in meeting weld reinforcement design thickness requirements. Peening the unacceptable indication prior to welding is permitted.

(2) If weld repair of indications identified in 1(d) is required, the area where the weld overlay is to be deposited, including any local weld repairs or initial weld overlay layer, shall be examined using the liquid penetrant method. The area shall contain no indications with major dimensions greater than 1/16 in. (1.5 mm) prior to the application of the structural layers of the weld overlay.

(3) In order to reduce the risk of cracks when applying an austenitic nickel alloy over P-No. 8 base metal, it is permissible to apply a layer of austenitic stainless steel filler material over the austenitic base metal. The thickness of these layers shall not be used in meeting weld reinforcement design thickness requirements.

(e) Weld overlay deposits shall meet the following requirements:

The austenitic nickel alloy weld overlay shall consist of at least two weld layers deposited using a filler material with a Cr content of at least 28%. The first layer of weld metal deposited may not be credited toward the required thickness.

Alternatively, a first 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 contain 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.

(f This alternative is only for welding in applications predicted not to have exceeded thermal neutron (E < 0.5 eV) fluence of 1 x 1017 neutrons per cm 2 prior to welding.

(g) A new weld overlay shall not be installed over the top of an existing weld overlay that has been in service.

Serial No.14-114 Docket No. 50-336, Enclosure 1, Page 3 of 7

2) CRACK GROWTH AND DESIGN (a) Crack Growth Calculation of Flaws in the Original Weld or Base Metal - The size of flaws detected or postulated in the original weld or base metal shall be used to define the life of the overlay. In no case shall the inspection interval be longer than the life of the overlay. The inspection interval shall be as specified in 3(b). Crack growth in the original weld or base metal, due to both stress corrosion and fatigue, shall be evaluated.

Flaw characterization and evaluation shall be based on the examination results, as described below. If the flaw is at or near the boundary of two different materials, evaluation of flaw growth in both materials is required.

(1) For repair overlays, the initial flaw size for crack growth shall be based on the as-found flaw or based on the postulated flaw, if no pre-overlay examination is performed.

(2) For postulated flaws, the axial flaw length shall be set at 1.5 in. (38 mm) or the combined width of the weld plus buttering, whichever is greater. The circumferential flaw length shall be assumed to be 360 degrees.

(b) Structural Design and Sizing of the Overlay - The design of the weld overlay shall satisfy the following, using the assumptions and flaw characterization restrictions in 2(a).

The following design analysis shall be completed in accordance with IWA-4311:

(1) The axial length and end slope of the weld overlay shall cover the weld and heat-affected zones on each side of the weld and provide for load redistribution from the item into the weld overlay and back into the item without violating applicable stress limits of NB-3200 or the Construction Code.

Any laminar flaws in the weld overlay shall be evaluated in the analysis to ensure that load redistribution complies with the above.

(2) Unless specifically analyzed in accordance with 2(b)(1), the end transition slope of the overlay shall not exceed 30 degrees with the nozzle/pipe axis.

(3) For determining the combined length of circumferentially oriented flaws in the underlying base material or weld, multiple flaws shall be treated as one flaw of length equal to the sum of the lengths of the individual flaws characterized in accordance with IWA-3300.

(4) For circumferentially oriented flaws in the underlying base material or weld, the flaws shall be assumed to be 100% through the original wall thickness for the entire circumference.

(5) For axial flaws in the underlying base material or weld, the flaws shall be assumed to be 100% through the original wall thickness of the item for the entire axial length of the flaw or combined flaws, as applicable, for the entire circumference.

(6) For mitigative full structural overlays, the assumed flaw in the underlying base material or weld shall be based on the limiting case of (a) or (b) below:

Serial No.14-114 Docket No. 50-336, Enclosure 1, Page 4 of 7 (a) 100% through-wall for the entire circumference (b) 100% through-wall for 1.5 in. (38 mm) or the combined width of the weld plus buttering, whichever is greater, in the axial direction for the entire circumference (7) The overlay design thickness shall be verified using only the weld overlay thickness conforming to the deposit analysis requirements of 1(e). The combined wall thickness at the weld overlay, or any postulated worst-case planar flaws under the laminar flaws in the weld overlay, and the effects of any discontinuities (e.g., another weld overlay or reinforcement for a branch connection) within a distance of 2.SVR-from the toes of the weld overlay, including the flaw size assumptions defined in 2(b)(4), (5), or (6) above, shall be evaluated and meet the requirements of IWB-3640, IWC-3640, or IWD-3640, as applicable. Ultrasonic examination procedures and personnel used to perform ultrasonic examinations shall be qualified in accordance with Appendix VIII, Supplement 10.

(8) The effects of any changes in applied loads, as a result of weld shrinkage from the entire overlay, on other items in the piping system (e.g., support loads and clearances, nozzle loads, and changes in system flexibility and weight due to the weld overlay) shall be evaluated. Existing flaws previously accepted by analytical evaluation shall be evaluated in accordance with IWB-3640, IWC-3640, or IWD-3640, as applicable.

3) EXAMINATION In lieu of all other examination requirements, the examination requirements of this alternative shall be met. Nondestructive examination methods shall be in accordance with IWA-2200, except as specified herein. Nondestructive examination personnel shall be qualified in accordance with IWA-2300.

Ultrasonic examination procedures and personnel shall be qualified in accordance with Appendix VIII, Supplement 11, as described in Attachment 1, Enclosure 2.

(a) Acceptance Examination (1) The weld overlay shall have a surface finish of 250 pin. (6.3 pm) RMS or better and contour that permits ultrasonic examination in accordance with procedures qualified in accordance with Appendix VIII. The weld overlay shall be inspected to verify acceptable configuration.

(2) The weld overlay and the adjacent base material for at least 1/2 in. (13 mm) from each side of the overlay shall be examined using the liquid penetrant method.

The weld overlay shall satisfy the surface examination acceptance criteria for welds of the Construction Code or NB-5300.

The adjacent base metal shall satisfy the surface examination acceptance criteria for base material of the Construction Code or NB-2500.

Serial No.14-114 Docket No. 50-336, Enclosure 1, Page 5 of 7 (3) The acceptance examination volume A-B-C-D in Fig. 1(a) shall be ultrasonically examined to assure adequate fusion (i.e., adequate bond) with the base metal and to detect welding flaws, such as interbead lack of fusion, inclusions, or cracks. The interface C-D shown between the overlay and the weld includes the bond and heat affected zone from the overlay.

(a) Planar flaws detected in the weld overlay acceptance examination shall meet the preservice examination standards of IWB-3514. In applying the acceptance standards to planar indications, the thickness tj, or t2 defined in Fig. 1(b), shall be used as the nominal wall thickness in IWB-3514, provided the base metal beneath the flaw (i.e., safe end, nozzle, or piping material) is not susceptible to stress corrosion cracking (SCC).

For susceptible material, tj shall be used. If a flaw in the overlay crosses the boundary between the two regions, the more conservative of the two dimensions (tj, ort 2) shall be used.

(b) Laminar flaws detected in the weld overlay shall meet the following requirements:

1. The acceptance standards of IWB-3514 shall be met, with the additional limitation that the total laminar flaw area shall not exceed 10% of the weld surface area, and that no linear dimension of the laminar flaw area exceed the greater of 3 in. (76 mm) or 10 % of the nominal pipe circumference.

2. For examination volume A-B-C-D in Fig. 1(a), the reduction in coverage due to laminar flaws shall be less than 10%.

The uninspectable volume is the volume in the weld overlay underneath the laminar flaws for which coverage cannot be achieved using the angle beam examination method.

3. Any uninspectable volume in the weld overlay shall be assumed to contain the largest radial planar flaw that could exist within that volume.

This assumed flaw shall meet the preservice examination acceptance standards of IWB-3514, with nominal wall thickness as defined above for planar flaws. Alternatively, the assumed flaw shall be evaluated and shall meet the requirements of IWB-3640, IWC-3640, or IWD-3640, as applicable. Both axial and circumferential planar flaws shall be assumed.

(4) After completion of associated welding activities, VT-3 visual examination shall be performed on affected restraints, supports, and snubbers, to verify that their operability and functional adequacy have not been adversely affected.

Serial No.14-114 Docket No. 50-336, Enclosure 1, Page 6 of 7 (b) Preservice and Inservice Examination Preservice and Inservice Examination shall comply with ASME Code Case subject to the conditions specified in paragraphs (g)(6)(ii)(F)(2)

(g)(6)(ii)(F)(10) of 10CFR50.55a.

N-770-1, through A

End Transition Slope (not to exceed 30-degrees, unless anraoyzed)

BY C

(a) Examination Volume A-B-C-D EK[-b 1 I

r--

b -1 A

0 I

if-

&\\ý'

H

\\I F

B t2 i

(b) Thickness (t, and t 2 ) for Table IWB-3514-2 FIG. I EXAMINATION VOLUME AND THICKNESS DEFINITIONS GENERAL NOTES:

1. Dimension "b" is equivalent to the nominal thickness of the nozzle or pipe being overlaid, as appropriate.

2. The nominal wall thickness is t, for flaws in E-F-G-H, and t2 for flaws in A-E-H-D or F-B-C-G.

3. For flaws that span two examination volumes (such as illustrated at F-G),

the t, thickness shall be used.

4. The weld includes the nozzle or safe end butter, where applied, plus any SCC susceptible base material in the nozzle.

Serial No.14-114 Docket No. 50-336, Enclosure 1, Page 7 of 7

4) PRESSURE TESTING A system leakage test shall be performed in accordance with IWA-5000.

5) DOCUMENTATION Use of this alternative shall be documented on Form NIS-2A.

Serial No.14-114 Docket No. 50-336 ATTACHMENT 1 ENCLOSURE 2 TABLE 1 MODIFICATIONS TO ASME CODE, SECTION XI, APPENDIX VIII, SUPPLEMENT II FOR THE USE OF ALTERNATIVE REQUEST RR-04-20 MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 1 of 9 MODIFICATIONS TO ASME CODE. SECTION XI, APPENDIX VIII, SUPPLEMENT 11 FOR THE USE OF ALTERNATIVE REQUEST RR-04-20 Appendix VIII of American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code), Section Xl cannot be used directly for nondestructive examination (NDE) of a structural weld overlay repair. Therefore, an alternative is proposed to use the Performance Demonstration Initiative (PDI) program implementation of Appendix VIII, for use with alternative request RR-04-20. A detailed comparison of Appendix VIII, Supplement 11 and PDI requirements is summarized below.

The proposed alternative allows closer spacing of flaws provided they do not interfere with detection or discrimination. The specimens used to date for qualification to the tri-party (NRC/BWROG/EPRI) agreement have a flaw population density greater than allowed by current Code requirements.

These sample specimens have been used successfully for previous qualifications under the tri-party agreement program.

To facilitate their use and provide continuity from the tri-party agreement program to Supplement 11, the PDI program has merged the tri-party test specimens into their weld overlay program with the following alternatives.

Table 1 Alternatives to Appendix VIII, Supplement 11 Supplement 11 - Qualification PDIProgram:.:

Requireernts for Full Structural Overlaid The Proposed Alternative to

,,,ýWrought Austenitic Piping Welds Supplement11 Requirements..

1.0 SPECIMEN REQUIREMENTS 1.1 General. The specimen set shall conform to the following requirements.

(b) The specimen set shall consist of at least Alternative: (b) The specimen set shall three specimens having different nominal pipe include specimens with overlays not thicker diameters and overlay thicknesses. They shall than 0.1 in. more than the minimum thickness, include the minimum and maximum nominal nor thinner than 0.25 in. of the maximum pipe diameters for which the examination nominal overlay thickness for which the procedure is applicable. Pipe diameters within examination procedure is applicable.

a range of 0.9 to 1.5 times a nominal diameter Basis: To avoid confusion, the overlay shall be considered equivalent. If the thickness tolerance contained in the last procedure is applicable to pipe diameters of 24 sentence was reworded and the phrase "and in. or larger, the specimen set must include at the remainder shall be alternative flaws" was least one specimen 24 in. or larger but need added to the next to last sentence in not include the maximum diameter. The paragraph 1. 1(d)(1).

specimen set must include at least one specimen with overlay thickness within -0.1 in.

to +0.25 in. of the maximum nominal overlay thickness for which the procedure is applicable.

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 2 of 9 Table I Alternatives to Appendix VIII, Supplement 11 Supplement 11 - Qualification PDl Program:

Requirements for Full Structural Overlaid The Proposed Alternative to

-Wrought Austenitic Piping Welds..

Supplement 11: Requirements (d) Flaw Conditions (1) Base metal flaws. All flaws must be cracks in or near the butt weld heat-affected zone, open to the inside surface, and extending at least 75% through the base metal wall. Flaws may extend 100% through the base metal and into the overlay material; in this case, intentional overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the cracking. Specimens containing IGSCC [intergranular stress corrosion cracking] shall be used when available.

Alternative: (1)... must be cracks in or... extending at least 50% through....

intentional overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the base metal flaws.

Specimens containing intergranular stress corrosion (IGSCC) cracking shall be used when available. At least 70% of the flaws in the detection and 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 and to extend at least 75 percent through the base metal wall.

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 PD/ 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

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 3 of 9 Table 1 Alternatives to Appendix VIII, Supplement 11 Supplement 11 - Qualification Requirements for Full Structural Overlaid Wrouaht Austenitic Pibina Welds PDI Program:

The Proposed Alternative to Sum~lement 1I1 Requirements I.

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) was revised to state that flaws must extend at least 50% through the base metal wall. This allows qualification to take advantage of additional test specimens to demonstrate increased examination depth.

i (e) Detection Specimens i

(1) At least 20% but less than 40% of the flaws shall be oriented within +200 of the pipe axial direction. The remainder shall be oriented circumferentially. Flaws shall not be open to any surface to which the candidate has physical or visual access. The rules of IWA-3300 shall be used to determine whether closely spaced flaws should be treated as single or multiple flaws.

Alternative: (1) At least 20% but less than 40% of the base metal flaws shall be oriented within +200 of the pipe axial direction. The remainder shall be oriented circumferentially.

Flaws shall not be open to any surface to which the candidate has physical or visual access.

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 [gas tungsten arc welding]

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.

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 4 of 9 Table I Alternatives to Appendix VIII, Supplement II

..Supplement 11 - Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds PDI Program:

The Proposed Alternative tO.

Supplement 11 Requirements.

(2) Specimens shall be divided into base and overlay grading units. Each specimen shall contain one or both types of grading units.

Alternative: (2) Specimens shall be divided into base metal and overlay 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.

Basis: Inclusion of "metal" and "fabrication" provides clarification. Flaw identification is improved by ensuring flaws are not masked by other flaws.

(a)(1) A base grading unit shall include at least 3 in. of the length of the overlaid weld. The base grading unit includes the outer 25% of the overlaid weld and base metal on both sides. The base grading unit shall not include the inner 75% of the overlaid weld and base metal overlay material, or base metal-to-overlay interface.

Alternative: (a)(1) A base metal grading unit includes the overlay material and the outer 50% of the original overlaid weld. The base metal grading unit shall extend circumferentially for at least 1 inch and shall start at the weld centerline and be wide enough in the axial direction to 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 PD! 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 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 inch of the length of the overlaid weld, rather than 3 inches.

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 5 of 9 Table I Alternatives to Appendix VIII, Supplement 11 Supplement I1 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative to Wrought Austenitic Piping Welds:i::

Supplement 11 Requirements (a)(2) When base metal cracking penetrates Alternative: (a)(2) When base metal flaws into the overlay material, the base grading unit penetrate into the overlay material, the base shall include the overlay metal within 1 in. of metal grading unit shall not be used as part of the crack location. This portion of the overlay any overlay fabrication grading unit.

material shall not be used as part of any Basis: Substituted terms provide clarification overlay grading unit.

and are consistent with 1d(1) above. The PDI program adjusts for this conservative change for excluding this type grading unit.

(a)(3) When a base grading unit is designed to Alternative: (a)(3) Sufficient unflawed be unflawed, at least 1 inch of unflawed overlaid weld and base metal shall exist on all overlaid weld and base metal shall exist on sides of the grading unit to preclude interfering either side of the base grading unit. The reflections from adjacent flaws.

segment of weld length used in one base grading unit shall not be used in another base Basis: Modified to require sufficient unflawed grading unit. Base grading units need not be overlaid weld and base metal to exist on all uniformly spaced around the specimen.

sides of the grading unit to preclude interfering reflections from adjacent flaws, rather than the 1 inch requirement.

(b)(1) An overlay grading unit shall include the Alternative: (b)(1) An overlay fabrication overlay material and the base metal-to-overlay grading unit shall include the overlay material interface of at least 6 in2. The overlay grading and the base metal-to-overlay interface for a unit shall be rectangular, with minimum length of at least 1 inch.

dimensions of 2 inches.

Basis: The PDI program reduces the base metal-to-overlay interface to at least 1 inch (in lieu of a minimum of 2 inches) and eliminates the minimum rectangular dimension. This criterion is necessary to allow use of existing examination specimens that were fabricated in order to meet NRC Generic Letter 88-01. This criterion may be more challenging than the ASME Code because of the variability associated with the shape of the grading unit.

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 6 of 9 Table I Alternatives to Appendix VIII, Supplement 11 Supplement I V-Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds PDI Program:

The Proposed Alternative to Supplement 11 Requirements (b)(2) An overlay grading unit designed to be unflawed shall be surrounded by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 inch around its entire perimeter. The specific area used in one overlay grading unit shall not be used in another overlay grading unit. Overlay grading units need not be spaced uniformly about the specimen.

Alternative: (b)(2) 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 inch at both ends. Sufficient unflawed overlaid weld and base metal shall exist on both sides of the overlay fabrication grading unit to preclude 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.

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 inch at both ends, rather than around its entire perimeter.

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

Alternative: (b)(3)... base metal grading units, ten unflawed base metal grading units, five flawed overlay fabrication grading units, and ten unflawed overlay fabrication grading units. For 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.

Basis: Clarified the guidance for initial procedure qualifications versus qualifying new values of essential variables.

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 7 of 9 Table 1 Alternatives to Appendix VIII, Supplement II Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid The Proposed Alternative to Wrought Austenitic Piping Welds Supplement II Requirements (f) Sizing Specimen (1) The minimum number of flaws shall be ten.

Alternative: (1) The.... least 40% of the At least 30% of the flaws shall be overlay flaws shall be open to the inside surface.

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

dimensions to assess sizing capabilities. For initial procedure qualification, sizing sets shall include the equivalent of three personnel qualification sets. To qualify new values of essential variables, at least one personnel qualification set is required.

Basis: Clarified the guidance for initial procedure qualifications versus qualifying new values of essential variables and is consistent with 1.1(d)(1) above.

(3) Base metal cracking used for length sizing Alternative:

(3) Base metal flaws used...

demonstrations shall be oriented circumferentially.

circumferentially.

Basis: Clarified wording to be consistent with 1.1((d)(1) above.

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

Basis: Clarified wording to be consistent with 1.1(d)(1) above.

2.0 CONDUCT OF PERFORMANCE DEMONSTRATION The specimen inside surface and identification Alternative: The specimen..... prohibited.

shall be concealed from the candidate. All The overlay fabrication flaw test and the base examinations shall be completed prior to metal flaw test may be performed separately.

grading the results and presenting the results Basis: Clarified wording to describe process.

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

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

specific grading units shall not be revealed to Basis: Clarified wording similar to 1. 1(e)(2) the candidate, the candidate shall be made above.

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 8 of 9 Table I Alternatives to Appendix VIII, Supplement 11 Supplement 11 - Qualification PDI Program:

Requirements for Full Structural Overlaid.

The Proposed Alternative to Wrought Austenitic Piping Welds Supplement 11 Requirements aware of the type or types of grading units (base or overlay) that are present for each specimen.

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

candidate shall estimate the length of that part 50% of the base metal wall thickness.

of the flaw that is in the outer 25% of the base Basis: Clarified wording for consistency and wall thickness.

to be consistent with 1. 1(d)(1) above.

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

candidate. For the remaining flaws, the (b) When the depth sizing test is conducted in regions of each specimen containing a flaw to conjunction with the detection test and the be sized shall be identified to the candidate.

detected flaws do not satisfy the requirements The candidate shall determine the maximum of 1.1 (f), additional specimens shall be depth of the flaw in each region.

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.

Basis: Clarified wording to better describe process.

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

results of the performance demonstration

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

and for overlay grading units.

b. At least one successful personnel demonstration has been performed meeting

Serial No.14-114 Docket No. 50-336, Enclosure 2, Page 9 of 9 Table 1 Alternatives to Appendix VIII, Supplement 11 Supplement 11 - Qualification.

Requirements for Full Structural Overlaid Wrouqht Austenitic PipingmWelds PDI Program:

The Proposed Alternative to Supplement,11 Reauirements 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: Clarified wording to better describe the difference between procedure qualification and equipment and personnel qualifications.

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

Alternative: (a)... The length of base metal flaws is... 50 % through base metal position.

Basis: Clarified wording to be consistent with 1.1(d)(1) above.

(b) All extensions of base metal cracking into the overlay material by at least 0.1 in. are reported as being intrusions into the overlay material.

Alternative: (b) This requirement is omitted.

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 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.

Serial No.14-114 Docket No. 50-336 ATTACHMENT 2 COMMITMENT

SUMMARY

MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.14-114 Docket No. 50-336, Page 1 of 1 Commitments Associated with RR-04-20 Commitment Due Date

1. A preliminary report shall be submitted with results of evaluations that are described in Paragraphs g(2) and g(3) of Code Case N-504-4, which requires the following information:

evaluations of residual stresses and flaw growth of the repaired welds.

effects of any changes in applied loads as a result of weld shrinkage from the entire overlay on other items in the piping system analysis to confirm that the requirements of sub articles NB-3200 and NB-3600 of the ASME Code,Section III are satisfied. The analysis includes the crack growth calculations to demonstrate that crack growth in the weld overlay or base metal is acceptable and residual stress distribution in the weld overlay and original weld demonstrate favorable stress distribution.

Prior to entry into Mode 4 following the completion of the weld overlays

.4-

2. The following information will be submitted to the NRC within 14 days of completion of the final ultrasonic examination of the FSWOL installations:

a listing of indications detected the disposition of the indications using the standards of ASME Code Section Xl, IWB-3514-2 and/or IWB-3514-3 criteria and, if possible, the type and nature of the indications a discussion of any repairs to the weld overlay material and/or base metal and the reason for the repairs Within 14 days of completion of the final ultrasonic examination of the FSWOL installations

3. A final report shall be submitted with results of evaluations that are described in Paragraphs g(2) and g(3) of Code Case N-504-4, which requires the following information: