SBK-L-12063, Response to Request for Additional Information Second 10-Year Interval Inservice Inspection Program Plan Requests for Relief

Response to Request for Additional Information Second 10-Year Interval Inservice Inspection Program Plan Requests for Relief

ML120790313
Person / Time
Site:	Seabrook
Issue date:	03/13/2012
From:	Freeman P NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-12063, TAC ME6901, TAC ME6902, TAC ME6903, TAC ME6904
Download: ML120790313 (34)

Text

NEXTera ENERGYP j March 13, 2012 SBK-L-12063 Docket No. 50-443 U.S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Seabrook Station Response to Request for Additional Information Second 10-Year Interval Inservice Inspection Program Plan Requests for Relief (TAC Nos. ME6901, ME6902, ME6903, AND ME6904)

References:

1. NextEra Energy Seabrook, LLC letter SBK-L- 11164, "End of Second 10-Year ISI Interval Relief Request For Examinations With Limited Coverage," dated August 17, 2011. (ML11234A185)

2. NRC Letter "Seabrook Station Unit 1 - Request for Additional Information Regarding the Second 10-Year Interval Inservice Inspection Program Plan Requests For Relief, TAC Nos. ME6901, ME6902, ME 6903, and ME6904)," dated January 11, 2012.

(MLI 13550209)

In Reference 1, NextEra Energy Seabrook, LLC (NextEra) submitted its request for relief for examinations with limited coverage on the basis that the required examination coverage is impractical due to physical obstructions and limitations imposed by design or geometry.

In Reference 2, the NRC requested additional information in order to complete its review of the request.

The attachment to this letter contains the requested additional information.

Should you have questions of a technical nature regarding the additional information, please contact Mr. Kevin Whitney, Principal Nuclear Engineer, at (603) 773-7043.

NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874 0 -.

U.S Nuclear Regulatory Commission SBK-L-12063/Page 2 Should you have any questions regarding this submittal, please contact Mr. Michael O'Keefe, Licensing Manager, at (603) 773-7745.

Sincerely, NextEra Energy Seabrook, LLC Paul Freeman Site Vice President

Attachment:

Response to Request for Additional Information Second 10-Year Interval Inservice Inspection for Program Plan Requests for Relief (TAC Nos. ME6901, ME6902, ME6903, AND ME6904) cc:

W.M. Dean, NRC Region I Administrator J. G. Lamb, NRC Project Manager, Project Directorate 1-2 W. J. Raymond, NRC Resident Inspector

Attachment Response to Request for Additional Information Second 10-Year Interval Inservice Inspection for Program Plan Requests for Relief (TAC Nos. ME6901, ME6902, ME6903, AND ME6904)

Response to Request for Additional Information Second 10-Year Interval Inservice Inspection for Program Plan Requests for Relief (TAC Nos. ME6901, ME6902, ME6903, AND ME6904) 2.1 Request for Relief 21R-17, ASME Code,Section XI, Table IWC-2500-1, Examination Category C-A, Items C 1.10 and C 1.30, Pressure Retaining Welds in Pressure Vessels The licensee has included Residual Heat Removal (RHR) Heat Exchanger Circumferential Shell Weld RH E-9B 01B and Containment Building Spray (CBS) Heat Exchanger Tubesheet-to-Shell Weld CBS E-16B 01 in this request. From the limited sketches and text provided, it is unclear which portion and how much of the ASME Code-required volumes have been completed, compared to the listed coverage percentages shown in Table 21R17-01 of the licensee's submittal dated August 17, 2011.

(a) Please submit detailed cross-sectional drawings showing volumetric coverage for each of the ultrasonic (UT) angles/techniques applied. Please include written descriptions of the ASME Code-required volumes and areas of completed coverage for each of the techniques used over the length of these welds.

NextEra Response:

The ASME Code-required volumes for these items are as required by the ASME B&PV Code,Section XI, Figures IWC-2500-1 and -2. These figures depict the examination volume requirements for IWC, Category C-A, Items C1.10 and Cl.30, respectively. As illustrated in Figures IWC-2500-1 and -2 the required examination volume includes the entire thickness of the weld and base material, including one half inch (0.50") of the adjacent base material on both sides of the weld.

Figures 21R- 17-03 and -04 have been provided to detail the volumetric coverage for each of the angles and techniques. Figure 21R-17-03 and -04 also illustrate the required ASME examination volume.

(b) The licensee stated that manual UT methods using, "the most recent technology available," was applied to maximize volumetric coverage. Please describe the specific technology that was used, e.g., phased array, composite search units, or other.

NextEra Response:

The welds listed in this relief request were examined using techniques required by ASME Section XI, IWA-2232 and Appendix I.

The specific technology included conventional, composite, and monolithic ultrasonic search units using shear and longitudinal wave modes. The techniques utilized angles, modes, and frequencies that are equivalent to the techniques required by the industry generic procedure for the manual "Ultrasonic Examination of Austenitic Piping Welds," PDI-UT-2. This is an ASME Code,Section XI, Appendix VIII, Supplement 2 qualified procedure for the detection of circumferential and axial flaws in austenitic piping welds when dual side access is available or if the flaw is located on the near side of a single side access configuration.

NextEra believes that the equipment and techniques used represent the most recent technology capable of maximizing volumetric coverage of the welds listed in this 1 of 31

relief. Refer to the discussion in 2.1 (c) that further describes the applicability of the PDI-UT-2 techniques, as well as limitations relative to the basis for "best effort" examination coverage of welds RH E-9B 01 B and CBS E- 16B 01.

(c) State whether procedures, personnel and equipment used on these welds were qualified through ASME Code,Section XI, Appendix VIII methods. If not, describe the qualification methodology, and provide a discussion on why the techniques applied would result in "best effort" coverage achieved on the near- and far-side of the subject weld volumes.

NextEra Response:

The ultrasonic procedure utilized met the requirements of ASME Code,Section XI, Appendix I and Appendix III as required. The ultrasonic procedure included equivalent techniques and equipment that are also specified for the inspection of the near and far side of welds from an Appendix VIII qualified industry generic procedure for austenitic piping welds, PDI-UT-2. The scope of PDI-UT-2 does not cover austenitic pressure vessel welds. However, the techniques in PDI-UT-2 are applicable due to the similar base and weld materials used for fabrication of welds RH E-9B 01B and CBS E-16B 01 . The techniques in PDI-UT-2 are not qualified to detect flaws that are on the far side of the weld when access is limited to a single side.

However, PDI-UT-2 does provide guidance to perform a "best effort" examination of the far side examination volume. The guidance provided in PDI-UT-2 for the detection of flaws on the far side of the weld is separated into two approaches based upon the thickness of the component being examined. The requirements are listed below:1

1) Piping equal to or less than 0.50" 2.25MHz x 700 shear wave search unit shall be used for detection and length sizing of flaws on the far side of the weld.

2) Piping greater than 0.50" A longitudinal wave search unit that provides adequate coverage of the far side of the weld shall additionally be used for detection and length sizing of flaws on the far side of the weld.

Examinations for both C-A items utilized PDI-UT-2 equivalent techniques for the detection of flaws located on the far side of the weld for thicknesses greater than 0.50", as well as allowable near side examination techniques for near side flaws. The specific examination UT parameters are listed in Table 21R-17-03.

As stated in 2. 1(a), Figures 21R-17-03 and -04 illustrate the required ASME examination volume and the coverage obtained by each examination angle. In these figures, examination volumes with less than 100% coverage are illustrated. The approximate coverage in the figures is representative 360' around the vessel for weld RH E-9B 01B but not for CBS E-16B 01. Weld RH E-9B 01B (Figure 21R-17-03) has a limitation due only to the geometry of the surface on the flange side of the weld which prohibits ultrasonic examination from that side. Weld CBS E-16B 01 (Figure

'PDI-UT-2, Rev E, Paragraph 6.8.1 c) and d) 2 of 31

21R- 17-04) has a similar limitation on the flange side but, it is also limited along the length of the weld on the near side due to attachment welds for the heat exchanger support. The near side limitation for CBS E-16B 01 is 60-inches of the 96-inches of circumferential length or approximately 63% of the weld length.

The coverage reported in Table 2IR- 17-03 for both welds is less than what can be estimated in the figures due to the limitation of ultrasonic inspection techniques in austenitic welds. The ultrasonic technique limitation is for the detection of flaws on the far side of austenitic welds when access is limited to examination from a single side. The primary obstacle for the reliable detection of flaws originating on the far side of austenitic welds is the anisotropic microstructural features found in austenitic coarse-grained materials.2 As a result NextEra has conservatively reported the estimated coverage based on the portion of the examination volume that was interrogated with ultrasonic beams prior to passing through the austenitic weld material.

Even though NextEra has conservatively reported the estimated coverage on the welds in this relief, it should be noted that some "best effort" far side coverage was achieved. The "best effort" far side coverage included, at a minimum, the weld to base material interface and portions of the heat affected zone (HAZ) at the inside surface. This area is the most likely initiation site for service-induced flaws in the systems selected. Coverage of this area of the examination volume is significant, considering the likelihood of flaw initiation in this region, and that industry Appendix VIII Supplement 2 demonstrations results and a recent study 2 indicate a fairly high detection rate of flaws >10% in through wall dimension using techniques described in PDI-UT-2.

The procedure utilized for examinations of welds CBS E-16B 01 and RH E-9B 01B is not required to be ASME Appendix VIII qualified. There is also no requirement for personnel and equipment to be Appendix VIII qualified. However, the ultrasonic instruments, search units, and techniques used for these examinations have all previously been successfully qualified by demonstration in accordance with the requirements of ASME Section XI, Appendix VIII, Supplement 2 using the industry generic procedure for the Examination of Austenitic Piping Welds, PDI-UT-2.

Additionally, personnel performing examinations were qualified by demonstration in accordance with the requirements of ASME Section XI, Appendix VIII, Supplement 2 as implemented by the PDA. NextEra believes that the equipment, techniques and examination personnel used provide reasonable assurance that service induced flaws would have been identified in the areas covered.

(d) For Weld CBS E- 16B 01, include information to better describe the welded support attachment and its impact on the examination, as this limitation could not be fully determined from Figure 21R-17-02 contained in the licensee's submittal dated August 17, 2011. NextEra Response:

Figure 21R-17-04 provides additional information regarding the impact of the welded support on the volumetric examination of weld CBS E-16B 01.

2 "An Assessment of Ultrasonic Techniques for Far-Side Examinations of Austenitic Stainless Steel Piping Welds", NUREG/CR-7113, PNNL-19353, ML12011A130, 2011 3 of 31

Table 21R-17-03 Examination Category C-A, Pressure Retaining Welds in Pressure Vessels Coverage Limitations and UT Parameters ISI Weld ID Item Configuration Thickness Coverage Angle Mode Frequency Comments Number RH E-9B OIB CI.10 "B" RHR Heat > 0.50" 50% 450 Shear Wave 2.25 MlHz Limited to the shell side due Exchanger Shell to the close proximity of the Circumferential flange to the weld. No service Weld 600 Longitudinal 2.0 MHz induced flaws were detected.

Wave See Figure 21R- 17-03 for cross-sectional details.

CBS E-16B 01 C1.30 "B" CBS Heat > 0.50" 19% 450 Shear Wave 2.25 MIHz Two limitations exist, the Exchanger weld is in close proximity to Tubesheet-to-Shell the flange, which limits Weld scanning from the shell side of the weld and welded support Longitudinal attachments, which prohibit 600 Wave 2.0 MHz access to the weld in those locations, No service related flaws were detected. See Figure 21R-17-04 for cross-sectional details.

4 of 31

Figure 21R-17-03 Residual Heat (RH) Heat Exchanger 1-RH-E-9B Circumferential Weld Detail (Exam Limitation Sketch) fýý CLASS 3 CLASS 2 l" C b K -m .- '----.

• I £ I I PORTION OF ASME EXAM VOLUME WHERE COVERAGE CREDIT IS CLAIMED PORTION OF ASME EXAM VOLUME WHERE NO COVERAGE CREDIT IS CLAIMED REGARDLESS IF PLOTS INDICATED OTHERWISE 5 of 31

Figure 21R-17-04 Containment Building Spray (CBS) Heat Exchanger Tubesheet-to-Shell Weld, CBS E-16B 01 (Exam Limitation Sketch)

CROSS SECTIONAL VIEW OF OBSTRUCTIONS AT THE SUPPORT ATTACHMENTS CROSS SECTIONAL VIEW OF OBSTRUCTIONS BETWEEN THE SUPPORT ATTACHMENTS (NO COVERAGE ON EITHER SIDE OF THE WELD) (LIMITED COVERAGE ACHIEVED FROM ONE SIDE OF THE WELD)

REQU.5IE ASME {

REQUIRED EXAMINATION VOLUME CBS E-1 6B 01 j

PORTIONOF ASMEEXAMVOLUME CREDITIS CLAIMED WHERECOVERAGE PORTIONOF ASMEEXAMVOLUME WHERENOCOVERAGE CREDITIS CLAIMEDREGARDLESSIF PLOTSINDICATED OTHERWISE SECTION A-A 6 of 31

2.2 Request for Relief 21R- 18, ASME Code,Section XI, Table IWC-2500-1, Examination Category C-B, Item C2.21, Pressure Retaining Nozzle Welds in Vessels The licensee has included two CBS heat exchanger nozzle-to-shell welds in this request.

From the limited sketches and text provided, it is unclear which portion and how much of the ASME Code-required volumes have been completed compared to the listed coverage percentages shown in Table 21R-1 8-01 contained in the licensee's submittal dated August 17, 2011.

(a) Please submit detailed cross-sectional drawings showing volumetric coverage for each of the UT angles/techniques applied. Please include written descriptions of the ASME Code-required volumes and areas of completed coverage for each of the techniques used over the length of these welds.

NextEra Response:

The ASME Code required volume for this item is as required by the ASME B&PV Code,Section XI, Figure IWC-2500-4. This figure depicts the examination volume requirements for IWC, Category C-B, Item C2.21. As illustrated in Figures IWC-2500-4 the required examination volume includes the inner 1/3 of the weld and base material thickness, including one quarter inch (0.25") of the adjacent base material on both sides of the weld.

Figure 21R-18-02 was provided to detail the volumetric coverage for each of the angles and techniques. Figure 21R-18-02 also illustrates the required ASME examination volume.

(b) The licensee stated that manual UT methods using, "the most recent technology available," was applied to maximize volumetric coverage. Please describe the specific technology that was used, e.g., phased array, composite search units, or other.

NextEra Response:

The welds listed in this relief request were examined using techniques required by ASME Section XI, IWA-2232 and Appendix I.

The specific technology included conventional, composite, and monolithic ultrasonic search units using shear and longitudinal wave modes. The techniques utilized angles, modes, and frequencies that are equivalent to the techniques required by the industry generic procedure for manual "Ultrasonic Examination of Austenitic Piping Welds,"

PDI-UT-2. This procedure is an ASME Code,Section XI, Appendix VIII qualified procedure for detection of circumferential and axial flaws in austenitic piping welds when dual side access is available or if the flaw is located on the near side of a single side access configuration.

NextEra believes that equipment and techniques used represent the most recent technology capable of maximizing volumetric coverage on welds listed in this relief.

Please see the discussion in 2.2(c) that further describes the applicability of PDI-UT-2 techniques as well as its limitations relative to the basis for "best effort" examination coverage of welds RH E-9B 01B and CBS E-16B 01.

7 of 31

(c) State whether procedures, personnel and equipment used on these welds were qualified through ASME Code,Section XI, Appendix VIII methods. If not, describe the qualification methodology, and provide a discussion on why the techniques applied would result in "best effort" coverage achieved on the near- and far-side of the subject weld volumes.

NextEra Response:

The ultrasonic procedure utilized met the requirements of ASME Code,Section XI, Appendix I and Appendix III as required. The ultrasonic procedure included equivalent techniques and equipment that are also specified for the inspection of the near and far side of welds from an Appendix VIII qualified industry generic procedure for austenitic piping welds, PDI-UT-2. The scope of PDI-UT-2 does not cover austenitic pressure vessel welds. However, the techniques in PDI-UT-2 are applicable due to the similar base and weld materials used for fabrication of welds CBS E-16B N1 and CBS E-16B N2. The techniques in PDI-UT-2 are not qualified to detect flaws that are on the far side of the weld when access is limited to a single side.

However, PDI-UT-2 does provide guidance to perform a "best effort" examination of the far side examination volume. The guidance provided in PDI-UT-2 for the detection of flaws on the far side of the weld is separated into two approaches based upon the 3

thickness of the component being examined. The requirements are listed below:

1) Piping equal to or less than 0.50" 2.25MHz x 700 shear wave search unit shall be used for detection and length sizing of flaws on the far side of the weld.

2) Piping greater than 0.50" A longitudinal wave search unit that provides adequate coverage of the far side of the weld shall additionally be used for detection and length sizing of flaws on the far side of the weld.

Examinations of both C-B items utilized PDI-UT-2 equivalent techniques for detection of flaws located on the far side of the weld for thicknesses greater than 0.50", as well as allowable near side examination techniques for near side flaws. The specific examination UT parameters are listed in Table 21R- 18-03 As stated in 2.2(a), Figure 21R-18-02 illustrates the required ASME examination volume and the coverage obtained by each examination angle. In this figure less than 100% examination coverage is illustrated. In Figure 21R- 18-02 the coverage of the required examination volume is approximately >90%. Welds CBS E-16B N I and CBS E-16B N2, in Figure 21R-18-02, have a limitation due only to the geometry of the weld joint and cannot be adequately examined from the opposite side of the weld due to the nozzle geometry.

The coverage reported in Table 21R- 18-03 for both welds is less than what can be estimated in the figures due to the limitation of ultrasonic inspection techniques in 3 PDI-UT-2, Rev E, Paragraph 6.8.1 c) and d) 8 of 31

austenitic welds. The ultrasonic technique limitation is for the detection of flaws on the far side of austenitic welds when access is limited to examination from a single side. The primary obstacle for reliable detection of flaws originating on the far side of austenitic welds is the anisotropic microstructural features found in austenitic coarse-grained materials. 4 As a result NextEra has conservatively reported estimated coverage based on the portion of the examination volume that was interrogated with ultrasonic beams prior to passing through the austenitic weld material.

Even though Seabrook has conservatively reported estimated coverage of the welds in this relief, it should be noted that some "best effort" far side coverage was achieved.

The "best effort" far side coverage included, at a minimum, the weld to base material interface and portions of the heat affected zone (HAZ) at the inside surface. This area is the most likely initiation site for service induced flaws in the systems selected.

Coverage of this area of the examination volume is significant, considering the likelihood of flaw initiation in this region, and that industry Appendix VIII Supplement 2 demonstrations results and a recent study 2 indicate a fairly high detection rate of flaws >10% in through wall dimension using techniques described in PDI-UT-2.

The procedure utilized for examinations of welds CBS E-16B NI and CBS E-16B N2 is not required to be ASME Appendix VIII qualified. There is also no requirement for personnel and equipment to be Appendix VIII qualified. However, ultrasonic instruments, search units, and techniques used for these examinations have all previously been successfully qualified by demonstration in accordance with the requirements of ASME Section XI, Appendix VIII, Supplement 2 using the industry generic procedure for the Examination of Austenitic Piping Welds, PDI-UT-2.

Additionally personnel performing examinations were qualified by demonstration in accordance with the requirements of ASME Section XI, Appendix VIII, Supplement 2 as implemented by the PDA. NextEra believes that the equipment, techniques and examination personnel used provide reasonable assurance that service induced flaws would have been identified in the areas covered.

(d) For "B" CBS Heat Exchanger Inlet Nozzle-to-Shell Weld, the weld identification in Tables 21R- 18-01 and -02 (CBS E- 16 N 1) in the licensee's submittal dated August 17, 2011 is different from the weld identification in Figure 21R-18-01 (CBS E-16B N1) contained in the August 17, 2011 submittal. Please specify the correct identification for this weld.

NextEra Response:

The correct identification of this weld is CBS E-16B N1.

4 "An Assessment of Ultrasonic Techniques for Far-Side Examinations of Austenitic Stainless Steel Piping Welds", NUREG/CR-7113, PNNL-19353, ML12011A130, 2011 9 of 31

Table 21R-18-03 Examination Category C-B, Pressure Retaining Nozzle Welds in Vessels Coverage Limitations and UT Parameters ISI Weld ID Item Configuration Thickness Coverage Angle Mode Frequency Comments Number CBS E-16B NI C2.21 "B" CBS Heat > 0.50" 50% 450 Shear Wave 2.25 MHz Limited examination from the Exchanger shell side due to nozzle-to-shell Nozzle-to-Shell weld configuration. No service Weld 600 Longitudinal 2.0 MHz related flaws were detected.

Wave See Figure 21R- 18-02 for cross-sectional details.

CBS E-16B N2 C2.21 "B" CBS Heat > 0.50" 50% 450 Shear Wave 2.25 MIHz Limited examination from the Exchanger shell side due to nozzle-to-shell Nozzle-to-Shell weld configuration. No service Weld 600 Longitudinal 2.0 MHz related flaws were detected.

Wave See Figure 21R- 18-02 for cross-sectional details.

10 of 31

Figure 21R-18-02 Containment Building Spray (CBS) Heat Exchanger Nozzle-to-Shell Welds, CBS E-16B N1 and N2 (Exam Limitation Sketch)

CROSS SECTIONAL VIEW OF CONFIGURATION AND EXAMINATION VOLUME PPR M-EEN2 ((SHOWING BEAM ANGLE COVERAGE ACHEIVED) 0.63" OUTLET .

/

0 ASME .ý iREQUIRED

• JPPORT MBE H T EEXAMINATION CBS HEAT EXCHANGER VOLUME SECTION A-A 0.25" oS 0.25" NOZ INLET /OUTLET TYPICAL WELD DETAILS CLASS 3 CLASS 2 L. INLET SUPR EBR[OUTKLET PORTION OF ASME EXAM VOLUME WHERE COVERAGE CREDIT IS CLAIMED PORTION OF ASME EXAM VOLUME WHERE NO COVERAGE CREDIT IS CLAIMED REGARDLESS IF PLOTS INDICATED OTHERWISE 11 of 31

2.3 Request for Relief 21R-19, ASME Code,Section XI, IWC-2500-1, Examination Category C-F-I, Items C5.11 and C5.21, Pressure Retaining Welds in Austenitic Stainless Steel or High Alloy Piping The licensee's submittal summarizes limited examinations performed during the second 10-year ISI interval, and provides calculated examination coverage for each piping weld.

However, the licensee's submittal provides only "typical" figures that do not describe or depict the specific limitations for each weld listed in Table 21R-19-01 of the licensee's submittal dated August 17, 2011.

(a) Please submit detailed and specific information to support the basis for each limited examination in Request for Relief 21R-19, and therefore, demonstrate impracticality.

Please include descriptions (written and/or sketches, as necessary) of the interferences to applied nondestructive examination (NDE) techniques. As applicable, describe NDE equipment, show accessibility limitations, and discuss whether alternative methods or advanced technologies could be employed to maximize ASME Code coverage.

NextEra Response:

A teleconference was held on January 10, 2012 between NextEra, the NRC project manager and the reviewers of NextEra's relief request 21R-19. As discussed, the additional information NextEra has provided below is in lieu of the requested "detailed and specific information" for each item. Instead, the information provided describes the limitation, which is generic to all of the items in this relief and is intended to demonstrate impracticality.

Each of the welds in RR 21R- 19 was limited to a single side of the component due to outside surface geometry on the opposite/far side of the weld joint. Specifically, the far side configuration prohibited scanning. In all cases, the far side limiting geometry is due to the configuration of piping system components such as valves, flanges, reducers, elbows and tees.

As stated in RR 21R- 19, configuration of the components prohibits complete coverage of the required ASME Section XI examination volume. In accordance with ASME B&PV Code Section XI, welds in this category must be examined using Appendix VIII, Supplement 2 qualified procedures and personnel as modified by 10 CFR 50.55a (b)(2)(xv)(A). Examination of the welds identified in RR 21R-19 utilized the industry generic procedure developed by the Performance Demonstration Initiative (PDI), "Ultrasonic Examination Procedure for Austenitic Pipe Welds," PDI-UT-2.

PDI-UT-2 has defined techniques for the detection and length sizing of service induced flaws since the original version. Since the initial qualification, PDI-UT-2 has contained a limitation for the detection of flaws on the far side of the weld.

Subsequent qualification demonstrations of other techniques have included both manual and automated methods for delivery of ultrasound with conventional and phased array ultrasonic techniques. However, none of these demonstrations have provided the industry with an Appendix VIII qualified technique for Supplement 2 12 of 31

welds with single side access configurations. The following limitation is stated in PDI-UT2, "the procedure is not qualified for the Detection or length sizing of circumferentially oriented flaws when only single side access is available and the flaw is located on the far side of the weld." This is also stated in all currently qualified Appendix VIII, Supplement 2 procedures.

The PDI-UT-2 defined techniques for near side flaw detection use shear wave search units. The near side flaw techniques are fully qualified in accordance with ASME Section XI, Appendix VIII. Due to the limitation for far side flaws, techniques for the detection of far side flaws is provided as guidance for the performance of "best-effort" examinations of the far side examination volume. The guidance provided in PDI-UT-2 for the detection of flaws on the far side of the weld is separated into two approaches based upon the thickness 5

of the component being examined. The requirements are listed below:

1) Piping equal to or less than 0.50" 2.25MHz x 700 shear wave search unit shall be used for detection and length sizing of flaws on the far side of the weld.

2) Piping greater than 0.50" A longitudinal wave search unit that provides adequate coverage of the far side of the weld shall additionally be used for detection and length sizing of flaws on the far side of the weld.

NextEra has reviewed the examination data reports, including weld thickness and contour (T and C) information for each of the welds in the relief request and has determined that they were all examined using the applicable far side flaw guidance specified in PDI-UT-2. This review also concluded that the maximum amount of "best effort" far sided examination volume coverage was achieved based the component geometry. Figures 21R- 19-03 and 21R- 19-04 represent actual cross sectional renderings of NextEra weld geometry. The figures have been generated from T and C information gathered in the field for the welds identified. Figure 21R-19-03 illustrates the <.050" thickness technique and 2IR-19-04 illustrates the > 0.50" thicknesses techniques of PDI-UT-2, as applied. Each figure shows two examples of welds where the far sided examination coverage was, (1) at its least and (2) at its greatest for the applicable technique thickness range. The examination coverage for the remainder of the welds in this relief are fully bounded by the examples given in Figures 21R- 19-03 and 21R- 19-04. The two figures and examples given within demonstrate how the PDI-UT2 techniques have been generically applied for all welds in this category.

Utilizing the cross sectional renderings for each item, NextEra estimated the examination coverage using the plotted examination angles. Only the central ray of the ultrasonic beam is plotted. No assumptions for ultrasonic beam width were considered. Examination coverage of 50% was reported when at least 100% of the 5PDI-UT-2, Rev E, Paragraph 6.8.1 c) and d) 13 of 31

near side base material was covered with the central ray of at least one of the required beam angles for the near side technique. "Best effort" coverage for the far side volume was fulfilled if the applicable far side technique was used and it provided at least some coverage of the far side weld and base material past the weld centerline.

The nominal 50% estimated coverage reported for the welds in RR 21R-19 is conservative given that the cross sectional plots for all of the welds show some portion of the exam volume on the far side as being interrogated with ultrasonic beams. However, the primary obstacle for the reliable detection of flaws originating on the far side of austenitic piping welds is the anisotropic micro structural features found in austenitic coarse-grained materials. 6 Consequently, NextEra is unable to report any examination coverage greater than 50%, even when the cross sectional plots may indicate otherwise.

While NextEra has conservatively reported the estimated coverage of the welds in this relief, it should be noted that some "best effort" far side coverage was achieved in all cases. The "best effort" far side coverage included, at a minimum, the weld to base material interface and portions of the heat affected zone (HAZ) at the inside surface.

This area is the most likely initiation site for service-induced flaws in the piping systems selected. Coverage of this area of the examination volume is significant, considering the likelihood of flaw initiation in this region, and that industry Appendix VIII Supplement 2 demonstrations results and a recent study 2 indicate a fairly high detection rate of flaws >10% in through wall dimension using techniques described in PDI-UT-2. For these reasons, NextEra believes that the examinations performed using the guidance for "best effort" far side flaw detection in PDI-UT-2 provides adequate inspection of the far side examination volume given the current industry limitations.

NextEra did not pursue alternative methods and advanced technologies as neither has been demonstrated to meet the ASME Section XI, Appendix VIII, Supplement 2 requirements as amended by 10CFR50.55a. Therefore, use of alternative methods and advanced technologies would not result in an increase quality and safety.

Table 21R-19-01 was revised with new formatting and additional information to assist in the review of 21R-19. The new format is presented in Table 21R-19-03. The additional information includes component thickness, examination angles, mode of propagation and frequency.

(b) The licensee's submittal states that the subject weld areas were interrogated with a combination of 45-, 60-, and/or 70-degree shear waves, and in some cases, 60- and 70-degree longitudinal waves (L-waves) were applied to detect circumferentially-oriented flaws. The licensee's submittal further states that examinations were performed in accordance with ASME Code,Section XI, Appendix VIII (performance demonstration initiative (PDI)), and consisted of single-sided examinations from the pipe side of the welds.

6 "An Assessment of Ultrasonic Techniques for Far-Side Examinations of Austenitic Stainless Steel Piping Welds," NUREG/CR-7113, PNNL-19353, ML12011A130, 2011.

14 of 31

(c) Please confirm the insonification angles and wave modalities used to examine each of the subject welds. Discussions with the industry's PDI administrator, the Electric Power Research Institute (EPRI), indicate that Supplement 2 qualifications require refracted longitudinal wave methods to be applied, if possible. If only shear wave techniques were used to examine the subject stainless steel welds, please explain why refracted longitudinal wave techniques where not used as part of a "best effort" examination. The L-wave method has been shown capable of detecting planar inside diameter (ID) surface-breaking flaws on the far-side of wrought stainless steel welds.

Recent studies7'8 recommend the use of both shear and L-waves to obtain the best detection results, with minimum false calls, in austenitic welds.

NextEra Response:

Table 21R-19-01 was revised with new formatting in order to confirm the angles and wave modes. The new format is presented in Table 21R- 19-03. The response given in Paragraph 2.3(a) provides the basis for the examination techniques used. The response provides specific details regarding when either both L-waves and S-waves were used or when only S-waves were used.

(d) For Elbow-to-Pipe Weld CS-0371-03-08, limitations were caused by the width of the weld crown. Please discuss any efforts that were used to correct the weld crown condition in order to maximize coverage.

NextEra Response:

At the time of this examination, grinding on final weld configurations was not considered. Based on examination limitations posed by weld crown width and geometry, this weld is being removed from ISI Program selection and relief request consideration.

7. F. V. Ammirato,, X. Edelmann, and S.M. Walker, Examination of DissimilarMetal Welds in BWR Nozzle-to-Safe End Joints, 8th InternationalConference on NDE in the Nuclear Industry, ASM International,1987.

8. P. T. Lemaitre, P., T.D. Koble, and S.R. Doctor, PISC 111 CapabilityStudy on Wrought-to-Wrought Austenitic Steel Welds: Evaluationat the Level of Proceduresand Techniques, Effectiveness of Nondestructive ExaminationSystems and Petformance Demonstration,PVP-Volume 317, NDE-Volume 14, ASME, 1995.

15 of 31

Figure 21R-19-03 Cross-Sectional Sketch Showing Minimum and Maximum Coverage Achieved for the <0.050" Techniques in PDI-UT-2 (Exam Limitation Sketch)

CBS 1212-16 10

/"""""""""'/' '" ASME REQURIED EXAM VOLUME CS 0324-01 01 0.25'--l 450 700 45' 70' VALVE 0.44"PIPE 113t ASME REQURIED EXAM VOLUME

[* PORTION OF ASME EXAM VOLUME COVERED WITH APPENDIX VIII QUALIFIED TECHNIQUES PORTION OF ASME EXAM VOLUME WHERE NO COVERAGE CREDIT IS CLAIMED REGARDLESS IF PLOTS INDICATED OTHERWISE 16 of 31

Figure 21R-19-04 Cross-Sectional Sketch Showing Minimum and Maximum Coverage Achieved for the >0.50" Techniques in PDI-UT-2 (Exam Limitation)

SI 0250-03 01 10.62" T0 ASMEREQURIED EXAMVOLUME RH 0155-02 32 ASME REQURIEDEXAMVOLUME I

PORTION OF ASME EXAMVOLUMECOVEREDWITHAPPENDIX VIIIQUALIFIEDTECHNIQUES PORTIONOF ASMEEXAMVOLUMEWHERE NO COVERAGECREDITIS CLAIMEDREGARDLESSIF PLOTS INDICATEDOTHERWISE 17 of 31

Table 21R-19-03 Examination Category C-F-i Pressure Retaining Welds in Austenitic Stainless Steel High Alloy Piping Coverage Limitations and UT Parameters iSI Weld ID Item Configuration Thickness Coverage Angle Mode Frequency Comments Number CBS 1207-02 C5.11 12" Pipe -to-Valve <.050" 50% 450 Shear Wave 2.25 MI-Hz Pipe side exam only due to 02 600 Shear Wave 2.25 MN-Iz close proximity of the valve 700 Shear Wave 2.25 MI-Iz taper to the weld.

CBS 1208-03 C5.11 10" Reducer-to- <.050" 50% 450 Shear Wave 2.25 MiHz Reducer side exam only due to 01 Pipe Flange close proximity of the flange 700 Shear Wave 2.25 MIHz taper to the weld.

CBS 1209-01 C5.11 12" Pipe -to-Valve <.050" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to 02 600 Shear Wave 2.25 M-z close proximity of the valve 700 Shear Wave 2.25 MHz taper to the weld.

600 Longitudina 4.0MHz 1 Wave CBS 1212-16 C5.11 16" Pipe -to-Valve <S050" 49% 450 Shear Wave 2.25 MITfz Pipe side exam only due to 10 close proximity of the valve 700 Shear Wave 2.25/5.0 taper to the weld. Additional TAT4, 10/. r*vlmrap* rechliItlnn IINP tM CBS 1214-02 C5.1 1 8" Valve- to- <.050" 50% 450 Shear Wave 2.25 M-lz Penetration side exam only due 21 Penetration 600 Shear Wave 2.25 MHz to close proximity of the valve 700 Shear Wave 2.25 NMz taper to the weld.

CBS 1215-01 C5.11 6" Flange-to-Pipe <.050" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to 01 close proximity of the flange to 700 Shear Wave 2.25 MFz the weld.

CBS 1216-02 C5.1 1 8" Pipe -to-Valve <.050" 50% 450 Shear Wave 2.25 MIHz Pipe side exam only due to 20 600 Shear Wave 2.25 M1-iz close proximity of the valve 700 Shear Wave 2.25 MHz taper to the weld.

CS 0324-01 01 C5.21 3" Pipe -to-Valve <.050" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to close proximity of the valve 700 Shear Wave 2.25 MHz taper to the weld.

18 of 31

Table 2IR-19-03 Examination Category C-F-1 Pressure Retaining Welds in Austenitic Stainless Steel High Alloy Piping Coverage Limitations and UT Parameters ISI Weld ID Item Configuration Thickness Coverage Angle Mode Frequency Comments Number CS 0324-01 C5.21 3" Valve -to- <.050" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to 02 Pipe close proximity of the valve 700 Shear Wave 2.25 MNiz taper to the weld.

CS 0355-01 C5.21 3" Valve -to- <.050" 50% 450 Shear Wave 5.0 MIHz Pipe side only exam due to 01 Pipe close proximity of the valve 700 Shear Wave 2.25 MHz taper to the weld.

CS 0355-01 C5.21 3" Pipe -to- <.050" 50% 450 Shear Wave 5.0 MiHz Pipe side only exam due to 04 Valve close proximity of the valve 700 Shear Wave 2.25 MHz taper to the weld.

CS 0355-06 C5.21 3" Pipe -to- <.050" 50% 450 Shear Wave 5.0 M-lz Pipe side exam only due to 01 Valve 600 Shear Wave 5.0 MHz close proximity of the valve 700 Shear Wave 2.25 MHz taper to the weld.

CS 0362-01 C5.21 4" Valve -to- > 0.50" 50% 450 Shear Wave 2.25 NMHz Pipe side exam only due to 02 Pipe close proximity of the valve 600 Longitudinal 4.0 M1z taper to the weld.

Wave CS 0364-01 C5.21 4" Flange-to- > 0.50" 50% 450 Shear Wave 2.25 M-l~z Pipe side exam only due to 01 Pipe 600 Shear Wave 2.25 M-l~z close proximity of the flange to 4.0 MHz the weld.

600 Longitudinal Wave CS 0364-02 C5.21 Weld removed from relief 01 request and ISI Program selection CS 0369-03 C5.21 8" Pipe -to- <.050" 50% 450 Shear Wave 2.25 MlHz Pipe side exam only due to 08 Valve 600 Shear Wave 2.25 MI-lz close proximity of the valve 700 Shear Wave 2.25 MHz taper to the weld.

19 of 31

Table 21R-19-03 Examination Category C-F-1 Pressure Retaining Welds in Austenitic Stainless Steel High Alloy Piping Coverage Limitations and UT Parameters ISI Weld Item Configuration Thickness Coverage Angle Mode Frequency Comments ID Number CS 0371- C5.21 Weld removed from relief request and 03 08 ISI Program selection.

CS 0374- C5.21 4" Flange -to- > 0.50" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to close 01 02 Pipe 700 Shear Wave 2.25 MfHz proximity of the flange to the weld.

600 Longitudinal 4.0 MIHz Wave CS 0375- C5.21 3" Valve -to- <.050" 50% 450 Shear Wave 5.0 M]Hz Pipe side exam only due to close 01 04 Pipe proximity of the valve taper to the 700 Shear Wave 2.25 MIHz weld.

RC 0013- C5.11 14" Pipe-to- <.050" 50% 450 Shear Wave 2.25 MI-z Pipe side exam only due to close 04 10 Nozzle proximity of the nozzle taper to the 700 Shear Wave 2.25 MHz weld.

RH 0152- C5.11 8" Valve-to- 5.050" 50% 450 Shear Wave 2.25 MIHz Pipe side exam only due to close 01 03 Pipe proximity of the valve taper to the 700 Shear Wave 2.25 MIHz weld.

RH 0155- C5.1 1 8" Pipe-to- > 0.50" 50% 450 Shear Wave 2.25 MN1z Pipe side exam only due to close 02 32 Valve Longitudinal proximity of the valve taper to the 600 Wave 2.0 MHz weld.

RH 0159- C5.1 1 8" Pipe-to- > 0.50" 50% 450 Shear Wave 2.25 MNHz Pipe side exam only due to close 0114 Valve Longitudinal proximity of the valve taper to the 600 Wave 2.0 M-z weld.

RH 0162- C5.11 6" Pipe-to- > 0.50" 50% 450 Shear Wave 1.5 MN-z Pipe side exam only due to close 04 02 Flange 600 Shear Wave 1.5 MHz proximity of the flange to the weld.

600 Longitudinal Wave 2.0 MHz 20 of 31

Table 21R-19-03 Examination CategoryC-F-1 Pressure Retaining Welds in Austenitic Stainless Steel High Alloy Piping Coverage Limitations and UT Parameters ISI Weld Item Configuration Thickness Coverage Angle Mode Frequency Comments ID Number RH 0163- C5.11 6" Flange-to- > 0.50" 50% 450 Shear Wave 1.5 MN-Hz Pipe side exam only due to close 05 04 Pipe 600 Shear Wave 1.5 MvHz proximity of the flange to the weld.

600 Longitudinal 2.0 MIHz Wave RH 0180- C5.11 8" Tee-to-Pipe > 0.50" 50% 450 Shear Wave 2.25 MIz Pipe side exam only due to close 01 01 600 Longitudinal proximity of the tee fitting taper to the 6 Wave 2.0 Miz weld.

SI 0250- C5.21 4" Valve -to- _S.050" 50% 450 Shear Wave 2.25 MNHz Pipe side exam only due to close 0207 Pipe 700 Shear Wave 2.25 M proximity of the valve taper to the weld.

SI 0250- C5.21 4" Valve -to- > 0.50" 50% 450 Shear Wave 2.25 MIHz Pipe side exam only due to close 03 01 Pipe 600 Longitudinal 4.0 MIHz proximity of the valve taper to the weld.

Wave SI 0250- C5.21 4" Pipe-to-Tee > 0.50" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to close 0304 004700 7 Longitudinal Lproximity 4.0 M~Hiz weld. of the tee fitting taper to the Wave SI 0251- C5.21 4" Pipe-to-  !<.050" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to close 02 08 Flange 600 Shear Wave 2.25 M-z proximity of the flange to the weld.

700 Shear Wave 2.25 MHz SI 0251- C5.21 4" Pipe -to- > 0.50" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to close 03 01 Valve 600 Shear Wave 2.25 Mi~z proximity of the valve taper to the weld.

600 Longitudinal 4.0 MiHz Wave SI 0256- C5.21 4" Valve-to- _<.050" 50% 450 Shear Wave 2.25 MHz Pipe side exam only due to close 01 02 Pipe 600 Shear Wave 2.25 MN-z proximity of the valve taper to the weld.

700 Shear Wave 2.25 MHz 21 of 31

Table 21R-19-03 Examination Category C-F-1 Pressure Retaining Welds in Austenitic Stainless Steel High Alloy Piping Coverage Limitations and UT Parameters ISI Weld ID Item Configuration Thickness Coverage Angle Mode Frequency Comments Number SI 0257-01 C5.21 4" Valve-to-Pipe <.050" 50% 450 Shear Wave 5.0 MHz Pipe side exam only due to 02 close proximity of the valve 7Q0 Shear Wave 2.25 MHz tprt h weld.

taper to the ed SI 0272-02 C5.21 4" Valve-to-Pipe > 0.50" 50% 450 Shear Wave 2.25 MIHz Pipe side exam only due to 10 close proximity of the valve taper to the weld.

600 Longitudinal 4.0 MHz Wave 22 of 31

2.4 Request for Relief 21R-20, Risk Informed ISI (RI-ISI), Category R-A, Items R. 11, R1.16 and R1.20, Risk Informed Piping Examinations The licensee's submittal summarizes limited examinations performed during the second 10-year ISI interval, and provides calculated examination coverage for each piping weld.

However, the licensee's submittal provides only "typical" figures that do not describe or depict the specific limitations for each weld listed in Table 21R-20-01 of the licensee's submittal dated August 17, 2011.

(a) Please submit detailed and specific information to support the basis for each limited examination in Request for Relief 21R-20, and therefore, demonstrate impracticality.

Please include descriptions (written and/or sketches, as necessary) of the interferences to applied NDE techniques. As applicable, describe NDE equipment, show accessibility limitations, and discuss whether alternative methods or advanced technologies could be employed to maximize ASME Code coverage.

NextEra Response:

A teleconference was held on January 10, 2012 between NextEra, the NRC project manager and the reviewers of NextEra's relief request 21R-19. As discussed, the additional information NextEra has provided below is in lieu of the requested "detailed and specific information" for each item. Instead, the information provided describes the limitation, which is generic to all of the items in this relief and is intended to demonstrate impracticality.

Each of the welds in RR 21R-20 was limited to a single side of the component due to outside surface geometry on the opposite/far side of the weld joint. Specifically, the far side configuration prohibited scanning. In all cases, the far side limiting geometry is due to the configuration of piping system components such as valves, flanges, reducers, elbows and tees.

As stated in RR 21R-20, the configuration of the components prohibits complete coverage of the required ASME Section XI examination volume. In accordance with ASME B&PV Code Section XI, welds in this category must be examined using Appendix VIII, Supplement 2 qualified procedures and personnel as modified by 10 CFR 50.55a (b)(2)(xv)(A). Examinations of the welds identified in RR 21R-20 utilized the industry generic procedure developed by the Performance Demonstration Initiative (PDI) "Ultrasonic Examination Procedure for Austenitic Pipe Welds," PDI-UT-2.

PDI-UT-2 has defined techniques for the detection and length sizing of service induced flaws since the original version. Since the initial qualification, PDI-UT-2 has contained the limitation for the detection of flaws on the far side of the weld.

Subsequent qualification demonstrations of other techniques have included both manual and automated methods for delivery of ultrasound with conventional and phased array ultrasonic techniques. However, none of these demonstrations have provided the industry with an Appendix VIII qualified technique for Supplement 2 welds for single side access configurations. The following limitations stated in PDI-23 of 31

UT2, "the procedure is not qualified for the Detection or length sizing of circumferentially oriented flaws when only single side access is available and the flaw is located on the far side of the weld" is also stated in all currently qualified Appendix VIII, Supplement 2 procedures.

The PDI-UT-2 defined techniques for near side flaw detection use shear wave search units. The near side flaw techniques are fully qualified in accordance with ASME Section XI, Appendix VIII. Due to the limitation for far side flaws, techniques for the detection of far side flaws is provided as guidance for the performance of "best-effort" examinations of the far side examination volume. The guidance provided in PDI-UT-2 for the detection of flaws on the far side of the weld is separated into two approaches based upon the thickness 9

of the component being examined. The requirements are listed below:

1) Piping equal to or less than 0.50" 2.25MHz x 700 shear wave search unit shall be used for detection and length sizing of flaws on the far side of the weld.

2) Piping greater than 0.50" A longitudinal wave search unit that provides adequate coverage of the far side of the weld shall additionally be used for detection and length sizing of flaws on the far side of the weld.

NextEra has reviewed the examination data reports, including weld thickness and contour (T and C) information for each of the welds in the relief request and has determined that they were all examined using the applicable far side flaw guidance specified in PDI-UT-2. This review also concluded that the maximum amount of "best effort" far sided examination volume coverage was achieved based the component geometry. Figures 21R-20-03 and 21R-20-04 represent actual cross sectional renderings of NextEra weld geometry. The figures have been generated from T and C information gathered in the field for the welds identified. Figure 21R-20-03 illustrates the <.050" thickness technique and 21R-20-04 illustrates the > 0.50" thicknesses techniques of PDI-UT-2, as applied. Each figure shows two examples of welds where the far sided examination coverage was, (1) at its least and (2) at its greatest for the applicabletechnique thickness range. The examination coverage for the remainder of the welds in this relief are fully bounded by the examples given in Figures 21R-20-03 and 21R-20-04.The two figures and examples given within demonstrate how the PDI-UT2 techniques have been generically applied for all welds in this category.

Utilizing the cross sectional renderings for each item, NextEra estimated the examination coverage using the plotted examination angles. Only the central ray of the ultrasonic beam is plotted. No assumptions for ultrasonic beam width were considered. Examination coverage of 50% was reported when at least 100% of the near side base material was covered with the central ray of at least one of the required 9 PDI-UT-2, Rev E, Paragraph 6.8.1 c) and d) 24 of 31

beam angles for the near side technique. "Best Effort" coverage for the far side volume was fulfilled if the applicable far side technique was used and it provided at least some coverage of the far side weld and base material past the weld centerline.

The nominal 50% estimated coverage reported for the welds in RR 21R-20 is conservative given that the cross sectional plots for all of the welds show some portion of the weld volume on the far side as being interrogated with ultrasonic beams. However, the primary obstacle for the reliable detection of flaws originating on the far side of austenitic piping welds is the anisotropic micro structural features found in austenitic coarse-grained materials.' 0 Consequently, NextEra is unable to report any examination coverage greater than 50%, even when the cross sectional plots may indicate otherwise.

While NextEra has conservatively reported the estimated coverage of the welds in this relief, it should be noted that some "best effort" far side coverage was achieved in all cases. The "best effort" far side coverage included, at a minimum, the weld to base material interface and portions of the heat affected zone (HAZ) at the inside surface.

This area is the most likely initiation site for service-induced flaws in the piping systems selected. Coverage of this area of the examination volume is significant, considering the likelihood of flaw initiation in this region, and that industry Appendix VIII Supplement 2 demonstration results and a recent study 2 indicate a fairly high detection rate of flaws >10% in through wall dimension using techniques described in PDI-UT-2. For these reasons, NextEra believes that the examinations performed using the guidance for "best effort" far side flaw detection in PDI-UT-2 provides adequate inspection of the far side examination volume given the current industry limitations.

NextEra did not pursue alternative methods and advanced technologies as neither has been demonstrated to meet the ASME Section XI, Appendix VIII, Supplement 2 requirements as amended by 10CFR50.55a. Therefore, use of the alternative methods and advanced technologies would not result in an increase quality and safety.

Table 21R-20-01 was revised with new formatting and additional information to assist in the review of 2IR1-20. The new format is presented in Table 21R-20-03. The additional information includes component thickness, examination angles, mode of propagation and frequency.

(b) The licensee's submittal states that the subject weld areas were interrogated with a combination of 45-, 60-, and/or 70-degree shear waves, and in some cases, 60- and 70-degree longitudinal waves (L-waves) were applied to detect circumferentially-oriented flaws. The licensee's submittal further states that examinations were performed in accordance with ASME Code,Section XI, Appendix VIII (performance demonstration), and consisted of single-sided examinations from the pipe side of the welds.

10 "An Assessment of Ultrasonic Techniques for Far-Side Examinations of Austenitic Stainless Steel Piping Welds", NUREG/CR-7113, PNNL-19353, ML1201I1A130, 2011.

25 of 31

(c) Please confirm the insonification angles and wave modalities used to examine each of the subject welds. Discussions with the industry's PDI administrator, EPRI, indicate that Supplement 2 qualifications require refracted longitudinal wave methods to be applied, if possible. If only shear wave techniques were used to examine the subject stainless steel welds, please explain why refracted longitudinal wave techniques were not used as part of a "best effort" examination. The L-wave method has been shown capable of detecting planar inside diameter (ID) surface-breaking flaws on the far-side of wrought stainless steel welds. Studies (see footnotes) recommend the use of both shear and L-waves to obtain the best detection results, with minimum false calls, in austenitic welds.

NextEra Response:

Table 21R-20-01 was revised with new formatting in order to confirm the angles and wave modes. The new format is presented in Table 21R-20-03. The response given in Paragraph 2.4(a) provides the basis for the examination techniques used. The response provides specific details regarding when either both L-waves and S-waves were used or when only S-waves were used.

(d) The licensee has requested relief from examining 100 percent of the ASME Code-required volumes for fifteen (15) ASME Code, Class 1 piping welds covered under a risk-informed ISI program.

(1) Please state the total number of ASME Code, Class 1 piping welds included in the overall risk-informed program so that the 15 limited examinations can be assessed within the scope of all examinations being implemented.

NextEra Response:

The Risk-Informed ISI (RI-ISI) program implemented during the second 10-Year interval was in accordance with ASME Code Case N-578 and EPRI topical report TR- 112657 and approved for use at NextEra per NRC SER dated February 7, 2002 (TAC No. MB11799). The RI-ISI program selected a total of 72 ASME Class 1 piping welds for examination.

(2) Please confirm that all other ASME Code, Class I piping examinations in the RI-ISI program have been completed in accordance with ASME Code volumetric requirements.

NextEra Response:

The 57 ASME Class 1 welds in the RI-ISI program not included in this request for relief were examined and met ASME Code volumetric requirements stated in approved ASME Code Case N-460 (i.e. >90% coverage).

(3) Further discuss whether additional welds could have been examined to augment the reduced volumetric coverage resulting from the limited examinations of the subject welds.

26 of 31

NextEra Response:

An Element Selection meeting was conducted and documented on September 13, 2000. The EPRI methodology requires element selection percentages of 25% for high risk categories and 10% for medium risk categories. Since within a given risk category, all elements are considered the same in terms of risk, elements were further subdivided based on the degradation mechanism type, system, pipe size and system function. This is the same type of process used in a standard ASME Section XI ISI program to distribute weld examinations between systems and line sizes. Though elements may be any part of the piping, only welds were selected.

Most selections were based on:

" Whether or not the weld had previously been examined (previously examined welds were given preference over welds that were not previously examined because the welds were known to be prepped, and had an examination history)

" Accessibility of the weld

• Radiological considerations

" Whether the weld was a dissimilar metal weld Additional unique factors were also considered. In general, branch connections and one-sided examinations (e.g., pipe-to-valve welds) were avoided when possible due to having limited coverage.

27 of 31

Figure 21R-20-03 Cross-Sectional Sketch Showing Minimum and Maximum Coverage Achieved for the <0.050" Techniques in PDI-UT-2 (Exam Limitation Sketch)

CS 0368-02 04

.J_ -- 1/3 [

RISK INFORMED ISIEXAMINATION VOLUME (INCLUDES ASME EXAM VOLUME)

CS 0366-02 04 0.44" RISK INFORMED ISI EXAMINATION VOLUME (INCLUDES ASME EXAM VOLUME)

PORTION OF REQUIRD EXAM VOLUME COVERED WITH APPENDIX VIII QUALIFIED TECHNIQUES PORTION OF REQUIRED EXAM VOLUME WHERE NO COVERAGE CREDIT IS CLAIMED REGARDLESS IF PLOTS INDICATED OTHERWISE 28 of 31

Figure 21R-20-04 Cross-Sectional Sketch Showing Minimum and Maximum Coverage Achieved for the >0.50" Techniques in PDI-UT-2 (Exam Limitation Sketch)

(1)

SI 0251-07 04 VALVE 60°S 60L 0.75" RISK INFORMED ISI EXAMINATIONVOLUME I INCLUDES ASME EXAM VOLUME)

RC 0048-03 01 70°S 45°S REDUCER 0.36, RISK INFORMED ISI EXAMINATION VOLUMI (INCLUDES ASME EXAM VOLUME)

PORTION OF REQUIRD EXAM VOLUME COVERED WITH APPENDIX VIII QUALIFIED TECHNIQUES PORTION OF REQUIRED EXAM VOLUME WHERE NO COVERAGE CREDIT IS CLAIMED REGARDLESS IF PLOTS INDICATED OTHERWISE 29 of 31

I . .

Table 21R-20-03 Examination Category R-A Pressure Retaining Welds in Austenitic Stainless Steel High Alloy Piping Coverage Limitations and UT Parameters ISI Weld Item Configuration Thickness Coverage Angle Mode Frequency Comments ID Number CS 0329- R1.20 Weld removed from relief request and ISI 04 04 Program selection.

CS 0366- RI.11 3" Valve-to- <.050" 50% 450 Shear Wave 2.25 MHz Limited examination from the pipe side only 02 04 Pipe due to close proximity of the valve taper to the 700 Shear Wave 2.25 MHz weld. No service related flaws were detected.

CS 0368- R1.1 1 3" Valve-to- <.050" 50% 450 Shear Wave 2.25 MiHz Limited examination from the pipe side only 02 04 Pipe due to close proximity of the valve taper to the 700 Shear Wave 2.25 MIHz weld. No service related flaws were detected.

RC 0013- R1.1 1 12" Pipe-to- > 0.50" 50% 450 Shear Wave 1.5 MHz Limited examination from the pipe side only 01 08 Tee Longitudinal due to close proximity of the tee fitting taper to 600 4.OMIHz the weld. No service related flaws were detected.

RC 0013- RI.1 1 12" Tee-to- > 0.50" 50% 450 Shear Wave 1.5 MI-Iz Limited examination from the pipe side only 01 09 Pipe due to close proximity of the tee fitting taper to 600 Longitudinal 4.0MHz the weld. No service related flaws were Wave detected.

RC 0048- Ri.11 4" Reducer-to- > 0.50" 50% 450 Shear Wave 2.25 MLHz Limited examination from the pipe side only 0301 Pipe due to close proximity of the reducer taper to 700 Longitudinal 4.OM]Hz the weld. No service related flaws were Wave detected.

RC0048- R1.11 Weld removed from relief request. Weld has 03 06 received full structural weld overlay and was not a limited exam in the interval.

RC 0080- R1.11 3" Pipe-to- 5.050" 50% 450 Shear Wave 2.25 MHz Limited examination from the pipe side only 02 10 Valve due to close proximity of the valve taper to the 700 Shear Wave 2.25 MHz weld. No service related flaws were detected.

30 of 31

A . .

Table 21R-20-03 Examination Category R-A Pressure Retaining Welds in Austenitic Stainless Steel High Alloy Piping COverage Limitations and UT Parameters ISI Item Configuration Thickness Coverage Angle Mode Frequency Comments Weld ID Number RC 0080- RI.11 3" Pipe-to- <.050" 50% 450 Shear Wave 2.25 MHz Limited examination from the pipe 06 10 Valve 700 Shear Wave 2.25 MHz side only due to close proximity of the ynllvp t~nr tA thp vplld NA oPryirt RC 0097- R1.20 3" Valve-to- <.050" 50% 450 Shear Wave 2.25 MHz Limited examination from the pipe 01 08 Pipe 700 Shear Wave 2.25 MHz side only due to close proximity of the vnlvP tnnpr tM thi wi-ld Nn vervice RC 0097- R1.20 3" Pipe-to- <.050" 50% 450 Shear Wave 2.25 MHz Limited examination from the pipe 01 11 Valve 600 Shear Wave 2.25 MHz side only due to close proximity of the valve taper to the weld. No service 700 Shear Wave 2.25 MHz related flaws were detected.

RH 0180- R1.11 12" Pipe-to- > 0.50" 50% 450 Shear Wave 2.25 MHz Limited examination from the pipe 0502 Tee 600 Shear Wave 2.25 MHz side only due to close proximity of the tee fitting taper to the weld. No 600 Long. Wave 4.0 MHz service related flaws were detected.

SI 0202- Ri.11 10" Valve-to- > 0.50" 50% 450 Shear Wave 2.25 MHz Limited examination from the pipe 02 17 Pipe 600 Longitudinal 2.0 MHz side only due to close proximity of the Wave valve taper to the weld. No service related flaws were detected.

SI 0251- R1.16 6" Pipe-to- > 0.50" 50% 450 Shear Wave 1.5 MHz Limited examination from the pipe 07 04 Valve 600 Shear Wave 1.5 MHz side only due to close proximity of the 60' Long. Wave 2.0 MHz valve taper to the weld. No service related flaws were detected.

SI 0251- R1.20 6" Valve-to- > 0.50" 50% 450 Shear Wave 1,5 M z Limited examination from the pipe 07 05 Pipe 600 Shear Wave 1.5 MHz side only due to close proximity of the 600 Longitudinal 2.0 MHz valve taper to the weld. No service Wave related flaws were detected.

31 of 31