Text

Relief Request 11-ON-002 Request for Additional Information (RAI) Response
	ML12270A372
Person / Time
Site:	Oconee
Issue date:	09/21/2012
From:	Gillespie T P; Duke Energy Carolinas
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	RR 11-ON-002
	Download: ML12270A372 (19)
	v • d • e

Duke T. PRESTON GILLESPIE, JR.Vice President PahEnergy Oconee Nuclear Station Duke Energy ONO VP / 7800 Rochester Hwy.Seneca, SC 29672 864-873-4478 864-873-4208 fax September 21, 2012 T. Gillespie@duke-energy.

com U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Duke Energy Carolinas, LLC (Duke Energy)Oconee Nuclear Station Units 2 and 3 Docket Numbers 50-270, -287 Relief Request 11-ON-002 Request for Additional Information (RAI) Response On February 29, 2012, Duke Energy submitted Relief Request 1 1-ON-002 (ADAMS Accession No. ML12066A1

75) pursuant to 10 CFR 50.55a(g)(5)(iii), requesting NRC approval from the requirement to examine 100% of the volume specified by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section Xl, Rules for Inservice Inspection of Nuclear Power Plant Components, 1998 Edition with 2000 Addenda (as modified by Code Case N-460).On August 11, 2012, the NRC Staff electronically requested additional information regarding this relief request. Duke Energy's response to the RAI is provided in the enclosure.

This submittal document contains no regulatory commitments.

If you have any questions or require additional information, please contact Corey Gray at (864) 873-6325.Sincerely, T. Preston Gillespie Jr, Site Vice President

Enclosure:

Oconee Nuclear Station Unit 2 and 3 Duke Response to Request for Additional Information (RAI) Relief Request 1 1-ON-002 2EOC-23, 3EOC-24, and 3EOC25 Limited Weld Exam AO70 www. duke-energy.

com U. S. Nuclear Regulatory Commission September 21, 2012 Page 2 xc (w/enclosure):

Victor Mcree Region II Administrator U. S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, Ga 30303-1257 John Boska Project Manager (by electronic mail only)U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation 11555 Rockville Pike Rockville, MD 20852 NRC Senior Resident Inspector Oconee Nuclear Station Susan Jenkins Section Manager Division of Waste Management Bureau of Land and Waste Management SC Dept. of Health & Environment Control 2600 Bull St.Columbia, SC 29201 cc: (w/o enclosure)

Enclosure Oconee Nuclear Station Unit 2 and 3 Duke Response to Request for Additional Information (RAI)Relief Request 11-ON-002 2EOC-23, 3EOC-24 and 3EOC-25 Limited Weld Examinations RAI # 11-ON-002 Response Page 1 RAI # 11-ON-002 Response Page 1 2.0 REQUESTS FOR ADDITIONAL INFORMATION Question 2.1 Requests for Relief 11-ON-002, Part A, ASME Code,Section XI, Examination Category B-B, Item B2.51, Pressure Retaining Welds in Vessels Other than Reactor Vessels (ON, Unit 3)2.1.1 The Letdown Cooler Inlet Channel Body-to-Chemical Connector Welds N32389-3 WJ-32 and N32389-3 WJ-35 required preservice examination.

Briefly describe nondestructive examinations that were performed on the subject welds during the replacement process, including examinations for construction code acceptance and/or preservice inspection in accordance with ASME Code Section X1. Please state whether any indications, discovered as a result of ASME Code-required construction and/or preservice examinations, could interfere with inservice ultrasonic (UT)examinations of the subject welds.Duke Response: Welds WJ-32 and WJ-35 (sections 25 and 27 of 1 1-ON-002) were preservice examinations.

These welds were procured by Duke Energy as part of a code stamped pressure vessel manufactured to the 1989 Edition of ASME Code Section III, Division I, Subsection ND (Class 3). The vessel manufacturer supplied an ASME form N-i, as required by the code. The data report certifies the manufacturer performed all construction code required examinations.

The examinations required by the construction code for these welds are radiography and hydrostatic testing. Per the data report, all examinations were acceptable under the construction code. The preservice examinations were UT and the results are included in the Relief Request 1 1-ON-002.

There were no indications discovered during construction or pre-service examination that are known to interfere with in-service UT examinations of the subject welds using current techniques.

2.1.2 The examination data sheets show a check mark next to "Yes" under indication, but there was no mention of these indications in the written description.

State what type, size, and how many indications were detected, as a result of ASME Code-required examination, and how these indications have been dispositioned.

Duke Response: The three indications listed for each of these two welds were dispositioned by examiners as two geometric indications from the weld root and one geometric reflector from the offset on the ID surface for each UT examination.

The indications detected during the examination were not associated with flaws within the component weld. The indications were acceptable without further evaluation.

The indications were *dispositioned using procedure guidance on probe skewing, use of higher angles, and indication plotting.RAI # 11-ON-002 Response Page 2 RAI # 11-ON-002 Response Page 2 2.2 Request for Relief 11-ON-002, Part B, ASME Code,Section XI, Examination Category B-D, Items B3.110 and B3.150, Full Penetration Welded Nozzles in Vessels (ON, Units 2 and 3)2.2.1 For the pressurizer (PZR) heater belt and upper shell-to-sampling nozzle welds (Item B3. 110), the licensee stated in section X. 4 (where X is a specific relief request section number) that the "scanning requirements described in ASME Code,Section V, Article 4, T-441.1.2(a), T-441.1.3, T-441.1.4, T-441.1.5, and T-441.1.6 could not be met." Besides not meeting the ASME Code, Section X1 volumetric code coverage, specifically describe which, if any, other requirements could not be met under ASME Code,Section V, Article 4.Duke Response: The reference to ASME Code,Section V, Article 4, T-441.1.2(a), T-441.1.3, T-441.1.4, T-441.1.5, and T-441.1.6 listed above is specific to scanning requirements only. All other examination requirements of ASME Section V, Article 4, except as noted in the relief request, were fully met.2.2.2 For some of the ASME Code, Section X1, Examination Category B-D welds, there was conflicting information presented in the written descriptions and the examination data.Section X. 7 (where X is a specific relief request section number) of the written description stated "acceptable results" and the examination data sheets had a check mark next to"Reject" under results, even when there was a check mark next to "No" indications found.In other cases, the examination data had a check mark next to "No" for indications and"Accept" under results. Clarify the inconsistencies as noted above. State whether any indications were discovered as a result of ASME Code-required examinations.

If any, state what type, size, and how many indications were detected, as a result of ASME Code-required examination, and how these indications have been dispositioned.

Duke Response: Current Duke Energy procedures require ASME Code, Section Xl examinations that do not meet the requirements of Code Case N-460 be marked "reject" for tracking purposes, regardless of whether indications were detected.

This process was implemented in August 2007. The B-D welds listed in Appendix C were PSI inspections performed in 2006.There were no recordable indications from these inspections.

At that time the reject box was not checked when Code coverage was not met. All other B-D welds listed in Appendix A and B were inspected following the procedure revision in 2007, and were properly marked as "reject" due to the Code coverage requirements not being met.2.2.3 In the Impracticality of Compliance section for all ASME Code, Examination Category B-D welds, the limitations are described as "...not allowing scanning from Surface 2." Provide a description of Surface 2 for each of the subject welds and the obstructions that prevent examination of Surface 2 for each of the subject welds.Duke Response: Pressurizer Nozzle to Shell welds were examined to the maximum extent practical for the nozzle geometries.

Coverage calculations and sketches illustrating the areas were provided in Attachments A and B in Relief Request 1 1-ON-002.

Surface 2 is identified as the nozzle for each weld.RAT # 11-ON-002 Response Page 3 RAI # 11-ON-002 Response Page 3 Letdown Nozzle to Channel Body welds were examined to the maximum extent practical for the nozzle geometries.

Coverage calculations and sketches illustrating the areas were provided in Attachments B and C in Relief Request 1 1-ON-002.

Surface 2 is identified as the nozzle for each weld.The coverage limitations for all category B-D welds were caused by the curvature of the scanning surface in the nozzle as it transitions from pipe to vessel. The curvature does not allow the sound wave to be directed into the entire required examination volume. To obtain the required coverage, the nozzle would need to be redesigned and replaced.

This is impractical.

2.2.4 The Letdown Cooler Outlet Nozzle-to-Channel Body Welds N32389-3 WJ-33 and N32389-3 WJ-36 required preservice examination.

Briefly describe the nondestructive examinations that were performed on the subject welds during the replacement process, including examinations for construction code acceptance and/or preservice inspection in accordance with ASME Code, Section X1.State whether or not any indications were discovered as a result of ASME Code-required construction and/or preservice examinations.

If any, describe how these indications would interfere with inservice UT examinations of the subject welds.Duke Response: The welds WJ-33 and WJ-36 (RFR sections 26 and 28) were preservice examinations.

These welds were procured by Duke Energy as part of a code stamped pressure vessel manufactured to the 1989 Edition of ASME Code Section III, Division I, Subsection ND (Class 3). The vessel manufacturer supplied an ASME form N-i, as required by the code. The data report certifies the manufacturer performed all construction code required examinations.

The examinations required by the construction code for these welds are radiography and hydrostatic testing. Per the data report, all examinations were acceptable under the construction code. The preservice examinations were UT and the results are included in the Relief Request 11-ON-002.

There were no indications discovered during construction or pre-service examination that are known to interfere with in-service UT examinations of the subject welds using current techniques.

2.3 Request for Relief 11-ON-002, Part C. ASME Code. Section Xl, Examination Category B-J. Item B9.11, Pressure Retaining Welds in PiDing (ON, Units 2 and 3)2.3.1 For Pipe-to- Valve 2LP- I Weld 2-53A- 10-3, the licensee did not provide a description of the limitation causing impracticality of performing the examination.

The license only provided a burden statement for modifications required to perform the ASME Code-required examination volume. Provide a description of the limitation causing the impracticality of performing the ASME Code examination of 100 percent of the weld volume for Pipe-to- Valve 2LP- 1 Weld 2-53A- 10-3.a) Include detailed descriptions (written and/or sketches, as necessary) of the interferences to the applied nondestructive examination (NDE) techniques.

RAI # 11-ON-002 Response Page 4 b) As applicable, describe NDE equipment (UT scanning apparatus), details of the listed obstructions (size, shape, proximity to the weld, etc.) to demonstrate accessibility limitations, and discuss whether or not any approved ASME Code, Section X1, Appendix VIII alternative methods or advanced technologies will be employed to maximize ASME Code coverage during the next 10-year ISI interval.Duke Response:

Section 5.4 of 1 1-ON-002 identifies the component as a cast stainless valve welded to a stainless steel pipe.This component was scanned manually with conventional methods.Scanning requirements are described in 10 CFR 50.55a(b)(2)(xv)(A)(1).

These requirements describe and are specific to scanning components in two axial and two circumferential directions.

This component was scanned to the extent possible to meet these requirements.

Best effort supplemental scanning was also performed using 600 refracted longitudinal waves for interrogation of the inner 1/3 of the wall thickness on the valve side, but is not qualified to be calculated into the above claimed coverage.

The supplemental refracted longitudinal waves were only used for interrogation in the axial direction per procedural direction.

Supplemental scanning is not performed in the circumferential direction.

The impracticality was caused by the taper configuration and cast stainless material of the valve body which cannot be effectively interrogated by ultrasound.

There are currently no examination techniques that have been qualified through Appendix VIII for examining cast stainless steel. Therefore no coverage could be obtained by scanning from the valve side. In order to scan all of the volume for this weld, the valve would have to be redesigned and replaced, which is impractical.

Attachment A in 1 1-ON-002 provides sketches for this configuration along with the coverage obtained to the extent possible.This weld was examined using procedures, equipment and personnel qualified in accordance with ASME Section XI, Appendix VIII.Radiography (RT) is not a desired option because RT is limited in the ability to detect service induced flaws and has not been qualified through performance demonstration.

Use of other manual or automated techniques, whether conventional or phased array, were considered, but would not increase coverage due to the limitation created by the cast stainless material.

The use of any other technique available would incur the same physical scanning limitations.

2.3.2 State whether a full surface examination was performed on each of the Reactor Coolant Pump (RCP) Casing Nozzle-to-Safe End Welds 3-PIA2-8, 3-PIB1-8, and 3-PDBI-1 and state whether any indications were discovered as a result of the surface examinations on each of the welds. If any, state what type, size, and how many indications were detected, as a result of ASME Code-required examination, and how these indications have been dispositioned.

RAI # 11-ON-002 Response Page 5 Duke Response: Welds 3-PIA2-8, 3-P1B1-8, and 3-PDBl-1 (original relief request sections 29, 30, and 33) did not receive a surface examination based on application of ASME Code Case N 663, Alternative Requirements for Classes 1 and 2 Surface Examinations,Section XI, Division 1. Since no surface examinations were performed, no surface indications were discovered.

2.3.3 For some ASME Code, Section Xl, Category B-J welds, there was conflicting information presented in the written descriptions and the examination data.Section X. 7 (where X is a specific relief request section number) of the written description stated"acceptable results" and the examination data sheets had a check mark next to "Reject" under results even when there was a check mark next to "No" indications found. In other cases the examination data had a check mark next to "No" for indications and "Accept" under results. State whether or not any indications were discovered as a result of ASME Code-required examination.

If any, state what type, size, and how many indications were detected, as a result of ASME Code-required examination, and how these indications have been dispositioned.

Duke Response: Duke Energy procedures require ASME Code,Section XI examinations that do not meet the requirement of Code Case N-460 to be markedreject" for tracking purposes regardless of whether indications were noted. Therefore, limited exams without indications were marked "reject".The process was implemented in August 2007. All Category B-J welds in this relief request were inspected in 2009 and 2010. All B-J welds were inspected with either PDI-UT-2 or NDE-600, which are the Appendix VIII, Supplement 2 piping procedures used for primary interrogation.

Data sheets listing these procedures are all correctly marked as "reject" due to the Code limited coverage.

These reports also include data sheets for NDE-830 for the "Best Effort" examination of the upper 2/3 region within the cast stainless steel valve side and/or NDE-640 for straight beam inspection of laminations.

These data sheets were each correctly marked as acceptable as neither provide Code required coverage calculated into the coverage obtained.No indications were recorded during any of these examinations.

2.3.4 The RCP 2B1 Casing Nozzle-to-Safe End Weld 2PIB1-8 and Pipe-to-Valve 2LP-1 Weld 2-53A-10-3 appear to be preservice examinations from the provided data sheets (Attachment A, Pages 17 through 30) but the written descriptions and Table 1 of the licensee's submittal dated February 29, 2012 indicate this is an inservice examination.

Please clarify what type of examination was performed for the subject welds.If these examinations were pre-service examinations, briefly describe nondestructive examinations that were performed on the subject welds during the replacement process, including examinations for construction code acceptance and/or preservice inspection in accordance with ASME Code Section X1. State whether any indications, were discovered as a result of ASME Code-required construction and/or preservice examinations, that could interfere with inservice UT examinations of the subject welds. In addition, Attachment A, pages 17 and 25, indicate that greater than 90 percent coverage was obtained, but in Attachment A, pages 19 and 27, the data sheets state that less than 90 percent coverage was obtained.

Please explain why the data sheets provided contain conflicting information, and clarify or correct this RAI # 11-ON-002 Response IPage 6 information.

If greater than 90 percent coverage was actually obtained for these welds, relief is not required and the licensee should formally withdraw these welds from this request for relief Duke Response:

02.B9.11.0058/2PIB1-8 was an ISI examination, as documented on Page 19 of 81 in Attachment A (UT Pipe Weld Examination).

No recordable indications were recorded from the inspection.

02.B9.11.0067/2-53A-10-3 was an ISI examination, as documented on Page 27 of 81 in Attachment A (UT Pipe Weld Examination).

No recordable indications were recorded from the inspection.

Attachment A, page 17 and 25 are properly marked as the UT Pipe Weld Examination forms are for NDE-640 which pertains only to the inspection of laminations, and therefore was not considered a limited examination.

Attachment A, page 19 and 27 are properly marked as these forms are for NDE-600 inspections which pertain to the actual Supplement 2 examinations that did not obtain the Code required coverage.2.4 Request for Relief 11-ON-002, Part D. ASME Code. Section Xl, Examination Category C-F-I. Items C5.11 and C5.21. Pressure Retaining Welds in Austenitic Stainless Steel or High Alloy PiDing (ON. Units 2 and 3)2.4.1 For ON, Unit 2, the licensee did not provide a description of the limitation(s) for each of the subject welds. The license only provided a burden statement for modifications required to perform the ASME Code-required examination volume. Provide a description of the limitations causing the impracticality of performing the ASME Code examination of 100 percent of the weld volume for the subject welds.a) Include detailed descriptions (written and/or sketches, as necessary) of the interferences to the applied NDE techniques.

b) As applicable, describe NDE equipment (UT scanning apparatus), details of the listed obstructions (size, shape, proximity to the weld, etc.) to demonstrate accessibility limitations, and discuss whether or not any approved ASME Code, Section X1, Appendix VIII alternative methods or advanced technologies will be employed to maximize ASME Code coverage during the next 10-year ISI Interval.Duke Response:

Section 6.4 of 1 1-ON-002 identifies the component as a cast stainless valve welded to a stainless steel pipe.This component was scanned manually with conventional methods.Scanning requirements are described in 10 CFR 50.55a(b)(2)(xv)(A)(1).

These requirements describe and are specific to scanning components in two axial and two circumferential directions.

This component was scanned to the extent possible to meet these requirements.

Best effort supplemental scanning was also performed using 600 refracted longitudinal waves for interrogation of the inner 1/3 of the wall thickness on the valve side, but is not qualified to be calculated into the claimed coverage.

The supplemental refracted longitudinal waves were RAI # 11-ON-002 Response Page 7 only used for interrogation in the axial direction per procedural direction.

Supplemental scanning is not performed in the circumferential direction.

The impracticality was caused by the taper configuration and cast stainless material of the valve body which cannot be effectively interrogated by ultrasound.

There are currently no examination techniques that have been qualified through Appendix VIII for examining cast stainless steel. Therefore, no coverage could be obtained by scanning from the valve side. In order to scan all of the volume for this weld, the valve would have to be redesigned and replaced, which is impractical.

Attachment A in 1 1-ON-002 provides sketches for this configuration along with the coverage obtained to the extent possible.This weld was examined using procedures, equipment and personnel qualified in accordance with ASME Section XI, Appendix VIII.Radiography (RT) is not a desired option because RT is limited in the ability to detect service induced flaws, and has not been qualified through performance demonstration.

Use of other manual or automated techniques, whether conventional or phased array, were considered, but would not increase coverage due to the limitation created by the cast stainless material.

The use of any other technique available would incur the same physical scanning limitations.

Section 7.4 of 1 1-ON-002 identifies the component as a forged stainless valve welded to a stainless steel pipe.This component was scanned manually with conventional methods.Scanning requirements are described in 10 CFR 50.55a(b)(2)(xv)(A)(1).

These requirements describe and are specific to scanning components in two axial and two circumferential directions.

This component was scanned to the extent possible to meet these requirements.

Best effort supplemental scanning was also performed using 600 refracted longitudinal waves for interrogation of the inner 1/3 of the wall thickness on the valve side, but is not qualified to be calculated into the above claimed coverage.

The supplemental refracted longitudinal waves were only used for interrogation in the axial direction per procedural direction.

Supplemental scanning is not performed in the circumferential direction.

The impracticality was caused by the taper configuration of the valve body which cannot be effectively interrogated by ultrasound.

Therefore, no coverage could be obtained by scanning from the valve side. In order to scan all of the volume for this weld, the valve would have to be redesigned and replaced, which is impractical.

Attachment A in 1 1-ON-002 provides sketches for this configuration along with the coverage obtained to the extent possible.RAI # 11-ON-002 Response Page 8 RAI # 11-ON-002 Response Page 8 This weld was examined using procedures, equipment and personnel qualified in accordance with ASME Section XI, Appendix VIII.Radiography (RT) is not a desired option because RT is limited in the ability to detect service induced flaws, and has not been qualified through performance demonstration.

Use of other manual or automated techniques, whether conventional or phased array, were considered, but would not increase coverage due to the limitation created by component configuration.

The use of any other technique available would incur the same physical scanning limitations.

Section 8.4 of 1 1-ON-002 identifies the component as a cast stainless valve welded to a stainless steel pipe.This component was scanned manually with conventional methods.Scanning requirements are described in 10 CFR 50.55a(b)(2)(xv)(A)(1).