DCL-14-111, American Society of Mechanical Engineers Section Xl Lnservice Inspection Program Relief Request NDE-RCS-SE-2R19 - Use of Alternate Sizing Qualification Criteria Through a Protective Clad Layer

American Society of Mechanical Engineers Section Xl Lnservice Inspection Program Relief Request NDE-RCS-SE-2R19 - Use of Alternate Sizing Qualification Criteria Through a Protective Clad Layer

ML14336A607
Person / Time
Site:	Diablo Canyon
Issue date:	12/02/2014
From:	Allen B Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-14-111
Download: ML14336A607 (15)

Text

Pacific Gas and Electric Company Barry S. Allen Diablo Canyon Power Plant Site Vice President Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.4888 Internal: 691.4888 December 2, 2014 Fax: 805.545.6445 PG&E Letter DCL-14-111 U.S. Nuclear Regulatory Commission 10 CFR 50.55a ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Power Plant (DCPP) Unit 2 American Society of Mechanical Engineers Section Xllnservice Inspection Program Relief Request NDE-RCS-SE-2R 19 - Use of Alternate Sizing Qualification Criteria Through a Protective Clad Laver

Reference:

1. PG&E Letter DCL-10-103, "ASME Section Xllnservice Inspection Program Relief Request NDE-RCS-SE-2R 16 Use of Alternate Sizing Qualification Criteria Through a Protective Clad Layer,"

dated August 12, 2010 (ML102350309)

Pursuant to 10 CFR 50.55a(g)(5)(iii), Pacific Gas and Electric Company (PG&E) hereby requests NRC approval of lnservice Inspection (lSI) Relief Request NDE-RCS-SE-2R 19 for the Diablo Canyon Power Plant (DCPP) Unit 2 Nineteenth Refueling Outage (2R 19). This request for relief (RR) proposes an alternative to the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Appendix VIII, Supplements 2 and 10 as modified by ASME Code Case N-695 "Qualification Requirements for Dissimilar Metal Piping Welds," and ASME Code Case N-696, "Qualification Requirements for Appendix VIII Examinations Conducted from the Inside Surface."

The details of the request and the technical basis for it are included in the Enclosure.

The DCPP inspection vendor has created a technical justification, WDI-T J-1044, Revision 1, "Demonstration Report/Technical Basis Document: Ultrasonic Examination of Diablo Canyon Unit 2 Reactor Pressure Vessel Nozzle-to-Safe End Welds from the ID Surface Through a Welded Protective Layer," to document the lSI process. Proprietary and nonproprietary versions of the vendor report were included in Reference 1. Both those reports are current, still valid, and applicable to the current relief request since the same process will be employed in the 2R 19 examinations of the reactor vessel nozzle-to-safe end and safe end-to-piping welds.

The Westinghouse authorization letter, CAW-1 0-2851, an accompanying affidavit, a Proprietary Information Notice, and a Copyright Notice that was included in A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canvon

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Document Control Desk PG&E Letter DCL-14-111 December 2, 2014 Page 2 Reference 1 is also applicable to the to the current relief request. Accordingly, PG&E requests that the Westinghouse proprietary information be withheld from public disclosure in accordance with 10 CFR 2.390.

To support the examinations to be performed in the upcoming 2R19 scheduled for May 2016, PG&E requests approval of Relief Request NDE-RCS-SE-2R 19 by December 2, 2015.

This communication contains new commitments to be implemented following NRC approval of this RR. The commitments are contained in Attachment 1 of the Enclosure.

If you have any questions, or require additional information, please contact Mr. Tom Baldwin at (805) 545-4720.

Sincerely, s!!.7ensAtL Site Vice President rntt/4231/SAPN 50033145 Enclosure cc: Diablo Distribution cc/enc: Marc L. Dapas, NRC Region IV Administrator Thomas R. Hipschman, NRC Senior Resident Inspector Siva P. Lingam, NRC Senior Project Manager Gonzalo L. Perez, California Department of Public Health State of California, Pressure Vessel Unit A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• South Texas Project

• Wolf Creek

Enclosure PG&E Letter DCL-14-111 10 CFR 50.55a Relief Request NDE-RCS-SE-2R19 in Accordance with 10 CFR 50.55a(g)(5)(iii)

--lnservice Inspection Impracticality--

Enclosure PG&E Letter DCL-14-111 10 CFR 50.55a Relief Request NDE-RCS-SE-2R19 in Accordance with 10 CFR 50.55a{g)(5){iii)

--lnservice Inspection Impracticality--

Table of Contents

1. ASME Code Component Affected

2. Applicable Code Edition and Addenda

3. Applicable Code Requirement

4. Impracticality of Compliance

5. Burden Caused by Compliance

6. Proposed Alternative and Basis for Use

7. Duration of Proposed Alternative

8. Precedents

9. References 1

Enclosure PG&E Letter DCL-14-111 10 CFR 50.55a Relief Request NDE-RCS-SE-2R19 in Accordance with 10 CFR 50.55a(g)(5)(iii)

--lnservice Inspection Impracticality--

1. ASME Code Components Affected The reactor vessel nozzle-to-safe end and safe end-to-piping welds are listed in the table below. See Figure 1.2 in Reference 2 for safe end general configuration and materials.

Code Cat./ Description Weld Number Line 10/

Item No.* Nominal Wall N-770-1, A-2 Loop 1 outlet nozzle-to-safe end WIB-RC-1-1 (SE) 29"/2.5" R-A, R1.20 Loop 1 outlet safe end-to-pipe WIB-RC-1-2 29"/2.5" R-A, R1.20 Loop 1 inlet elbow-to-safe end WIB-RC-1-15 27.5/2.38" N-770-1, B Loop 1 inlet safe end-to-nozzle WIB-RC-1-16(SE) 27.5/2.38" N-770-1, A-2 Loop 2 outlet nozzle-to-safe end WIB-RC-2-1 (SE) 29"/2.5" R-A, R1.20 Loop 2 outlet safe end-to-pipe WIB-RC-2-2 29"/2.5" R-A, R1.20 Loop 2 inlet elbow-to-safe end WIB-RC-2-15 27.5/2.38" N-770-1, B Loop 2 inlet safe end-to-nozzle WIB-RC-2-16(SE) 27.5/2.38" N-770-1 , A-2 Loop 3 outlet nozzle-to-safe end WIB-RC-3-1 (SE) 29"/2.5" R-A, R1.20 Loop 3 outlet safe end-to-pipe WIB-RC-3-2 29"/2.5" R-A, R1.20 Loop 3 inlet elbow-to-safe end WIB-RC-3-15 27.5/2.38" N-770-1, B Loop 3 inlet safe end-to-nozzle WIB-RC-3-16(SE) 27.5/2.38" N-770-1, A-2 Loop 4 outlet nozzle-to-safe end WIB-RC-4-1 (SE) 29"/2.5" R-A, R1.20 Loop 4 outlet safe end-to-pipe WIB-RC-4-2 29"/2.5" R-A, R1.20 Loop 4 inlet elbow-to-safe end WIB-RC-4-15 27.5/2.38" N-770-1, B Loop 4 inlet safe end-to-nozzle WI B-RC-4-16(SE) 27.5/2.38"

• Safe end welds with SE suffix are dissimilar metal welds fabricated with Alloy 182 weld material and are examined in accordance with ASME Code Case N-770-1.

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Enclosure PG&E Letter DCL-14-111

2. Applicable Code Edition and Addenda

The Diablo Canyon Power Plant (DCPP) third lnservice Inspection Interval Program Plan (ISIPP) is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 2001 Edition with 2003 Addenda. ASME Code,Section XI, 2001 Edition without Addenda applies to ultrasonic examinations performed per ASME Code Section XI, Appendix VIII requirements.

3. Applicable Code Requirement

The ISIPP is augmented with the requirements of ASME Code Case N-770-1 as modified by 10 CFR 50.55a for the examination of dissimilar metal vessel nozzle butt welds containing Alloy 82/182 material.

These requirements apply to the DCPP Unit 2 dissimilar metal welds connecting the reactor nozzles to the reactor coolant system (RCS) piping.

DCPP Risk Informed ISIPP examination Category R-A, Item R.120 (formerly Code Category 8-F, 85.10 in the 2001 Edition through 2003 Addenda), specifies volumetric examination for the RCS safe end to piping welds.

All of the specified ultrasonic (volumetric) examinations scheduled to be conducted in the Unit 2 nineteenth refueling outage (2R 19) are required to be performed per ASME Section XI, Appendix VIII (hereafter Appendix VIII), Supplements 2 (wrought austenitic welds) and 10 (dissimilar metal welds), with the exception of the cast side of the cold leg elbow-to-safe end welds. The rules of ASME Section XI, Appendix Ill (hereafter Appendix Ill) as modified by ASME Section XI, Appendix I, Supplement 1 (hereafter Supplement 1), are specified for the examination of the cast elbow sides of the cold leg welds.

The DCPP ISIPP 'references ASME Code Cases N-695 and N-696, which are unconditionally approved for use in NRC Regulatory Guide 1.147, Revision 16.

4. Impracticality of Compliance ASME Code Cases N-695 and N-696 provide alternatives to Appendix VIII, Supplements 10 and 2 and include criteria for depth sizing accuracy; Code Case N-695 paragraph 3.3(c) states: " ... are qualified for depth sizing when the RMS error of the flaw depth measurements, as 3

Enclosure PG&E Letter DCL-14-111 compared to the true flaw depths, do not exceed 0.125 in. (3 mm)" while Code Case N-696 paragraph 3.3(d) states: " ... qualified for depth sizing when the flaw depths estimated by ultrasonics, as compared with the true depths, do not exceed 0.125 in. (3 mm) RMS, when they are combined with a successful Supplement 10 qualification." Additionally, Code Case N-695 contains an exclusion in the scope section that states: "This Case is not applicable to piping welds containing supplemental corrosion resistant clad (CRC) applied to mitigate intergranular stress corrosion cracking."

The requirements for the 0.125 inch root mean square error (RMSE) depth sizing accuracy criteria of Code Cases N-695 and N-696 and the Code Case N-695 exclusion for examinations performed through CRC are impractical for DCPP to comply with. Likewise, implementing the requirements of Appendix Ill as modified by Supplement 1 for the examination of the cast stainless steel side of the cold leg elbow-to-safe end welds is impractical when the weld is required to be examined from the opposite side per Appendix VIII requirements. Details of the specific issues follow:

RMSE Error To date, although examination vendors have qualified for detection and length sizing in accordance with the requirements for examinations from the inside diameter (I D), the vendors have not met the established RMSE of 0.125 inch for indication depth sizing. Several process enhancements including new delivery systems, new search units and software modifications have been implemented but did not achieve the desired improvements in performance. This result indicates that the Code accuracy standard is impractical for use with the ID ultrasonic examination technology employed in the qualification efforts.

Code Cases N-695 and N-696. Examination through CRC The DCPP Unit 2 safe end welds and safe end forgings have a thin (nominal "t" of 0.090 inch; 0.073 inch to 0.125 inch in thickness) protective clad layer applied to the ID and outside diameter (OD) of the dissimilar metal weld and the safe end forgings.

During the DCPP Unit 2 reactor vessel fabrication process, the stainless steel safe end forgings were welded to the low alloy steel reactor nozzle forgings and heat treated with the entire vessel. This method resulted in the stainless steel safe end forging becoming "furnace sensitized." The protective clad layer is intended to act as a barrier to isolate the sensitized 4

Enclosure PG&E Letter OCL-14-111 safe end dissimilar metal weld and stainless steel safe end forging from the surrounding environment. Sketches of the OCPP Unit 2 safe end general configuration and material types are included in Figure 1.2 in Reference 2.

The DCPP Unit 2 RCS safe end configuration with the protective 10 and 00 clad layers applied to the dissimilar metal weld and safe end forgings is unique to a small number of Westinghouse designed units. As such, suitable "blind" test samples are not available to support Appendix VIII, Supplement 2 and 10 qualifications for the OCPP Unit 2 configuration.

Appendix Ill vs. Appendix VIII for 10 Examination of Cast Stainless Steel Elbows The DCPP Cold leg safe end forgings are welded to cast stainless steel elbows; therefore, a portion of the ASME XI specified exam area extends into the elbow casting. Due to the known difficulties associated with examining cast stainless steel, specific standards for examination of these materials are not yet included in Section XI. Additionally, the 00 configuration of the DCPP cold leg cast elbows is not suitable for ultrasonic examination.

Examination of the four subject welds from the 10 with two separate processes (Appendix VIII from the safe end side and Appendix Ill from the cast elbow side) is impractical due to the effort required to implement two separate examination technologies on a single weld without technical benefit for doing so.

5. Burden Caused by Compliance RMSE Error The numerous attempts by lSI vendors to meet the Supplements 2 and 10 and Code Cases N-695 and N-696 required RMSE value for depth sizing when examining from the inside diameter have been unsuccessful.

Furthermore, the outside surface configuration of the OCPP Unit 2 safe end welds are not suitable for examination; conditioning of the surface would require extensive effort and result in personnel exposure as described in the following section.

5

Enclosure PG&E Letter DCL-14-111 Code Cases N-695 and N-696. Examination through CRC The DCPP Unit 2 reactor vessel was fabricated in the 1970 timeframe, prior to implementation of Appendix VIII qualification requirements. The distinctive DCCP Unit 2 RCS safe end weld configuration is not encompassed by the industry's performance demonstration initiative (POl) program used to implement ASME XI, Appendix VIII requirements.

Consequently, no lSI vendor is qualified to examine the DCPP configuration.

Removing the protective clad from either the ID or OD of the RCS safe ends in order to create a configuration bounded by the POl sample sets would result in extensive personnel exposure and potentially reduce the overall structural integrity of the component. General area dose rates in the vicinity of the subject welds (ex-core annulus area), averages 150-200 millirem per hour. Considering that OD machining to remove the overlay and achieve the required surface finish could exceed 20 man hours per nozzle, the total personnel exposure would perhaps surpass 32 roentgen equivalent man (man-rem). ID machining of these locations would remove the protective layer and any benefit that the protective layer might afford to the underlying materials by isolating them from the surrounding environment.

Compliance with the POl qualification program without alternative implementation would necessitate significant modification to the reactor coolant system safe end welds. Alterations such as this may result in reduced structural integrity of the reactor coolant pressure boundary.

Appendix Ill vs. Appendix VIII for ID Examination of Cast Stainless Steel Elbows Application of Appendix Ill, Supplement 1 ID examinations would require separate procedures, calibration blocks, calibrations and possibly separate examination equipment than that used to conduct the Appendix VIII, Supplement 2 examinations on the wrought side of the weld. Examinations using the two separate processes on a single weld type would result in additional burden without benefit since the proposed Appendix VIII examination process supplemented by eddy current (EC) surface examination includes the additional method to aid in detection of inside surface connected flaws.

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Enclosure PG&E Letter DCL-14-111

6. Proposed Alternative and Basis for Use RMSE Error PG&E proposes to use a vendor qualified for ID detection and length sizing per Appendix VIII as applicable to the welds similar in configuration and materials (i.e., without CRC) to the welds included in this request.

Indications requiring depth sizing will be treated as detailed in the following paragraphs.

The examination vendor contracted to perform the safe end examinations at DCPP has demonstrated the ability to depth size indications in dissimilar metal welds with a RMSE of 0.189 inch instead of the 0.125 inch RMSE required by Appendix VIII Supplement 10 and Code Case N-695.

Additionally, the vendor has demonstrated the ability to depth size with a 0.245 inch RMSE when applying combined aspects of Appendix VIII, Supplements 2 and 10 per Code Case N-696.

If a reportable flaw is detected and determined to be ID surface connected during examination of the welds in accordance with this relief request, Pacific Gas and Electric Company (PG&E) will provide a flaw evaluation including the measured flaw size as determined by ultrasonic examination for review. EC testing will be used to determine if flaws are surface connected. Additional data including details of the surrounding ID surface contour in the region of the flaw and percentage of the exam area where UT (ultrasonic testing) probe lift-off is evident, if any, will be included.

In the event that any flaw(s) requiring depth sizing are detected during examination of welds in accordance with this relief request, the following criteria shall be implemented:

• Flaws detected and measured as less than 50 percent through-wall in depth shall be adjusted by adding a correction factor to the flaw depth such that the adjusted flaw depth is equal to the measured flaw depth+( applicable vendor RMSE - 0.125), prior to comparison to the applicable acceptance criteria;

• Flaws detected and measured as 50 percent through-wall depth or greater and to remain in service without mitigation or repair, PG&E shall submit flaw evaluation(s) for review and approval prior to reactor startup. The flaw evaluation shall include:

o Information concerning the mechanism that caused the flaw 7

Enclosure PG&E Letter DCL-14-111 o Information concerning the inside surface roughness/profile of the region surrounding the flaw o Information concerning areas where UT probe lift-off is observed All welds included in this request have been previously examined from the ID with an Appendix VIII detection process qualified on similar configurations and materials (i.e., without CRC) in the thirteenth refueling outage; the nozzle-to-safe end dissimilar metal welds were similarly examined again in the sixteenth refueling outage. The ultrasonic examinations were supplemented by surface profilometry and EC testing.

Greater than 90 percent coverage of the required exam areas was achieved in all cases. This inspection history confirms that the inside surface profiles of the welds included in this request are suitable for ultrasonic examination from the ID in accordance with the referenced requirements as modified by the proposed alternative sizing requirements.

Code Cases N-695 and N-696. Examination through CRC PG&E proposes to use vendor procedures, personnel and equipment qualified in accordance with the PDI implementation of Appendix VIII, Supplements 10 and 2 as modified by the requirements of Code Cases N-695 and N-696 to examine the nozzle-to-safe end dissimilar metal and safe end-to piping stainless steel welds from the ID through the protective clad layer.

PG&E's inspection vendor has performed additional demonstration activities in order to validate the ability to detect length size and depth size flaws through a clad layer and ID weld inlays. Although not identical, the open test samples, clad and weld layer thicknesses conservatively encompass the DCPP dissimilar metal weld configuration. The test samples include flaws of various depth and lengths oriented in both the axial and circumferential directions in the weld and heat affected zones for the dissimilar metal weld (representative of the nozzle to safe end welds).

When examining the test specimens, the vendor used a PDI qualified (detection and length sizing) ID examination procedure; the current revision of that same procedure will be employed in the 2R 19 examinations. The vendor demonstrated the capability to accurately detect, length and depth size the test sample flaws through CRC in each of the samples and configurations examined. The results of these activities verify that the proposed examination technique is appropriate for 8

Enclosure PG&E Letter DCL-14-111 application to the DCPP Unit 2 nozzle-to-safe welds and safe end-to-piping welds, since the vendor procedure is the same for both weld types.

The DCPP lSI vendor has created a technical justification, WDI-TJ-1044, Revision 1, "Demonstration Report/Technical Basis Document: Ultrasonic Examination of Diablo Canyon Unit 2 Reactor Pressure Vessel Nozzle-to-Safe End Welds from the ID Surface Through a Welded Protective Layer" to document the process and results of the additional demonstration activities . . Proprietary and nonproprietary versions of the vendor report were included in the previous PG&E Letter DCL-10-103, "ASME Section Xllnservice Inspection Program Relief Request NDE-RCS-SE-2R16 Use of Alternate Sizing Qualification Criteria Through a Protective Clad Layer," for Diablo Canyon Unit 2 (Reference 1).

Appendix VII liD Examination of Cast Stainless Steel Elbows PG&E proposes to use the vendor's examination procedure (same PDI Appendix VIII procedure qualified for detection and length sizing in wrought materials, described in the previous section) to examine the cast stainless steel side of the cold leg elbow-to-safe end welds in lieu of Appendix Ill and Supplement 1 requirements. AIIID examinations will be augmented with inside surface profilometry and EC examination. An Appendix VIII qualified examination process conducted from the ID and supplemented by EC is considered by PG&E to be more effective than the Code specified Appendix Ill examination.

Potential Failure Consequences In the event the proposed alternate examination process grossly mischaracterizes a significant planar flaw, the potential resulting failure of one of the RCS loop outlet/inlet welds could result in a loss of coolant accident (LOCA). Depending on the size of the postulated break, the specific consequences will vary. At the smallest end of the break size spectrum, the charging system would be capable of maintaining RCS pressure through normal makeup. Larger break sizes would result in depressurization of the RCS, reactor trip and a safety injection. The worst case consequence would occur if one of the nozzle to pipe welds were to suffer 360 degree through-wall circumferential cracking. In this case, the break size is bounded by the line ID, which is less than the break size used in the large break LOCA design basis analysis.

NRC review of vendor PDI qualification test results concluded that for flaw depths less than 50 percent wall thickness, reasonable assurance that a flaw will be appropriately depth sized may be obtained by adding a 9

Enclosure PG&E Letter DCL-14-111 correction factor to the flaw depth such that the adjusted flaw depth is equal to the measured flaw depth+(contractor RMSE-0.125). Therefore, the proposed alternative for correcting measured flaw depths for flaws less than 50 percent wall thickness and performing and submitting a flaw specific analysis for flaws equal to or greater that 50 percent wall thickness is unlikely to result in gross flaw mischaracterization and any potential for resulting component failure.

Conclusion All welds included in this request have been previously examined from the 10 with the Appendix VIII qualified (POl implementation) exam process.

The ultrasonic examinations were supplemented by surface profilometry and EC testing. Greater than 90 percent coverage of the required exam areas was achieved in all cases. This history confirms that the inside surface profile of these welds i~ suitable for ultrasonic examination from the 10 in accordance with the referenced requirements. PG&E will use the same ultrasonic exam process supplemented by surface profilometry and EC testing for safe end dissimilar metal weld examinations in 2R 19.

The supplemental vendor demonstration activities establish that the existing POl qualified inspection procedure and process is effective for examining dissimilar metal and stainless steel piping welds through welded layers on the pipe inside surface such as the DCPP configuration.

The potential sizing variation will be addressed by addition of the difference between demonstrated and required RMSE values.

The proposed alternatives assure that 10 ultrasonic examinations of the DCPP Unit 2 reactor coolant nozzle-to-safe end welds are performed using personnel, procedures, and equipment that are effective and provide an acceptable level of quality and safety in accordance with 10 CFR 50.55a(g)(5)(iii).

7. Duration of Proposed Alternative The duration of the proposed alternative is for safe end weld examinations for the remainder of the DCPP Unit 2 third lSI interval which commenced on July 1, 2006, and is nominally scheduled to end March 12, 2016.

NOTE: Per IWA 2430(d)(1) the third lSI inspection interval is being extended less than 1 year, to correspond to 2R19 scheduled for May 2016.

10

Enclosure PG&E Letter DCL-14-111

8. Precedents The proposed alternative method of adding the difference between the demonstrated and required RMSE values to the measured indication depth and the application of ASME Appendix VIII to cast stainless steel was approved for Diablo Canyon Unit 1 by NRC letter dated January 3, 2014 (ADAMS Accession No. ML13219A011).

Use of alternate sizing qualification criteria through a protective clad layer was approved for Diablo Canyon Unit 2 by NRC letter dated August 12, 2010 (ADAMS Accession No. ML102350295).

9. References

1. PG&E Letter DCL-10-103, "ASME Section Xllnservice Inspection Program Relief Request NDE-RCS-SE-2R 16 Use of Alternate Sizing Qualification Criteria Through a Protective Clad Layer," dated August 12, 2010 (ADAMS Accession No. ML102350309)

2. Enclosure 3 to PG&E Letter DCL-10-103, Westinghouse Report, WDI-TJ-1044-NP, Rev. 1, "Demonstration Report!Technical Basis Document: Ultrasonic Examination of Diablo Canyon Unit 2 Reactor Pressure Vessel Nozzle-to-Safe End Welds from the ID Surface Through a Welded Protective Layer" (ADAMS Accession No. ML102350297) 11

Attachment 1 PG&E Letter DCL-14-111 List of Regulatory Commitments Commitment 1 If a reportable flaw is detected and determined to be ID surface connected during examination of the welds in accordance with the Relief Request NDE-RCS-SE-2R 19, PG&E will provide a flaw evaluation including the measured flaw size as determined by ultrasonic examination for review.

Eddy current testing will be used to determine if flaws are surface connected. Additional data including details of the surrounding ID surface contour in the region of the flaw and percentage of the exam area where UT (ultrasonic testing) probe lift-off is evident, if any, will be included.

Commitment 2 In the event that any flaw(s) requiring depth sizing are detected during examination of welds in accordance with the Relief Request NDE-RCS-SE-2R19, the following criteria shall be implemented:

• Flaws detected and measured as less than 50 percent through-wall

• in depth shall be adjusted by adding a correction factor to the flaw depth such that the adjusted flaw depth is equal to the measured flaw depth+(applicable vendor RMSE - 0.125), prior to comparison to the applicable acceptance criteria;

• Flaws detected and measured as 50 percent through-wall depth or greater and to remain in service without mitigation or repair, PG&E shall submit flaw evaluation(s) for review and approval prior to reactor startup. The flaw evaluation shall include:

o Information concerning the mechanism that caused the flaw o Information concerning the inside surface roughness/profile of the region surrounding the flaw o Information concerning areas where UT probe lift-off is observed