ML091660654

Safety Evaluation for Relief Request VEGP-ISI-Alt-01 Proposed Alternative to ASME Code Requirements for the Third Inservice Inspection Interval

ML091660654
Person / Time
Site:	Vogtle
Issue date:	07/06/2009
From:	Melanie Wong Plant Licensing Branch II
To:	Ajluni M Southern Nuclear Operating Co
Wright D, NRR/DORL, 301-415 -1864
References
TAC ME1140, TAC ME1141
Download: ML091660654 (12)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 6, 2009 Mr. Mark J. Ajluni Manager, Nuclear Licensing Southern Nuclear Operating Company, Inc.

40 Inverness Center Parkway PO Box 1295 Birmingham, AL 35201

SUBJECT:

VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2, SAFETY EVALUATION FOR RELIEF REQUEST VEGP-ISI-ALT-01 PROPOSED ALTERNATIVE TO ASME CODE REQUIREMENTS FOR THE THIRD INSERVICE INSPECTION INTERVAL (TAC NOS. ME1140 AND ME1141)

Dear Mr. Ajluni:

By letter dated April 23, 2009 (Agencywide Document Access and Management System (ADAMS) Accession No. ML091140339), to the U.S. Nuclear Regulatory Commission (NRC),

Southern Nuclear Operating Company, Inc. (the licensee) submitted a proposed alternative VEGP-ISI-ALT-01, Version 1.0, for Vogtle Electric Generating Plant, Units 1 and 2 (VEGP 1 and 2). VEGP-ISI-ALT-01, Version 1.0, proposed an alternative to selected American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code),Section XI, requirements related to the qualifications for examination of pressure retaining welds in piping at VEGP 1 and 2. Specifically, the licensee proposed using ASME Code,Section XI, Appendix VIII, Supplement 11, "Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds," as administered by the Electric Power Research Institute, Performance Demonstration Initiative (PDI) Program.

The NRC staff has determined that the use of the proposed PDI Program will provide equivalent flaw detection to that of the ASME Code requirements for piping welds. The NRC staff finds that the licensee's proposed alternative will provide an acceptable level of quality and safety.

Therefore, pursuant to Title 10 of the Code of Federal Regulations, Section 50.55a(a)(3)(i), the NRC staff authorizes the use of alternative VEGP-ISI-ALT-01 at VEGP 1 and 2. The proposed alternative is applicable for the third inservice inspection interval which began May 31, 2007, and ends May 30, 2017.

M. Ajluni

- 2 If you have any questions, please contact the Project Manager, Donna Wright, at 301-415-1864.

Sincerely, Melanie C. Wong, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos.: 50-424 and 50-425

Enclosure:

Safety Evaluation cc wi encl: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE VEGP-ISI-ALT-01, VERSION 1.0 IMPLEMENTATION OF THE PERFORMANCE DEMONSTRATION INITIATIVE PROGRAM VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 SOUTHERN NUCLEAR OPERATING COMPANY, INC.

DOCKET NOS. 50-424 AND 50-425

1.0 INTRODUCTION

By letter dated April 23, 2009 (Agencywide Document Access and Management System (ADAMS) Accession No. ML091140339), to the U.S. Nuclear Regulatory Commission (NRC),

Southern Nuclear Operating Company, Inc., (the licensee) submitted a relief request from certain qualification requirements of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code) for Vogtle Electric Generating Plant, Units 1 and 2 (VEGP 1 and 2). Specifically, the licensee proposed in request VEGP-ISI-ALT-01 to use the ASME Code,Section XI, Appendix VIII, Supplement 11, "Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds," as administered by the Electric Power Research Institute (EPRI), Performance Demonstration Initiative (PDI) Program. The request applies to both units for the remainder of the third 1O-year inservice inspection (lSI) interval which began May 31,2007, and ends May 30,2017.

2.0 REGULATORY EVALUATION

The lSI of the ASME Code Class 1, 2, and 3, components is to be performed in accordance with Section XI of the ASME Code and applicable edition and addenda as required by Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g), except where specific relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) of 10 CFR states in part that alternatives to the requirements of paragraph (g) may be used when authorized by the NRC staff, if the applicant demonstrates that: (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The licensee proposed an alternative in accordance with 10 CFR 50.55a(a)(3)(i).

Pursuant to 10 CFR Section 50.55a(g)(4), ASME Code Class 1, 2, and 3, components (including supports) will meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the Enclosure

- 2 limitations of design, geometry, and materials of constrlJction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 1O-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. Section 50.55a(g)(4)(iv) of 10 CFR states that inservice examination of components and system pressure tests may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in 10 CFR 50.55a(b), subject to the limitations and modification listed in 10 CFR 50.55a(b) and subject to Commission approval. Portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met. The code of record for the third 10-year lSI interval at VEGP 1 and 2 is the 2001 Edition through 2003 Addenda of the ASME Code.

3.0 TECHNICAL EVALUATION

3.1 Affected Components The affected components are ASME Class 1 pressure retaining welds in piping subject to ASME Code,Section XI, Appendix VIII, Supplement 11, examinations.

3.2 Applicable Code The applicable Code is the 2001 Edition of ASME Section XI, as required by 10 CFR 50.55a(b)(2)(xxiv). The ultrasonic testing (UT) examination must be performed using personnel, procedures, and equipment qualified in accordance with Appendix VIII, Supplement 11. The selected paragraphs in Supplement 11 affected by this request for relief are:

1.1(b), 1.1(d)(1), 1.1(e)(1), 1.1(e)(2), 1.1 (e)(2)(a)(1), 1.1(e)(2)(a)(2), 1.1 (e)(2)(a)(3),

1.1(e)(2)(b)(1), 1.1(e)(2)(b)(2), 1.1(e)(2)(b)(3), 1.1(f)(1), 1.1(f)(3), 1.1(f)(4), 2.0, 2.1, 2.2(d), 2.3, 3.1, 3.2(a), and 3.2(b).

3.3 Proposed Alternative In lieu of the requirements of ASME Code,Section XI, 2001 Edition, Appendix VIII, Supplement 11, the licensee shall use the requirements of the EPRI-POI Program. The major differences between the 2001 Edition of the ASME Code, Section Xi, Appendix VIII, requirements and the POI Program are in an attachment to the licensee's submittal which are discussed below.

3.4 Licensee Basis for the Alternative The requirements for selected paragraphs of ASME Code,Section XI, Appendix VIII, Supplement 11, as stated in the 2001 Edition, as required by 10 CFR 50.55a(b)(2)(xxiv), as changed and implemented by the POI program follows:

Paragraph 1.1(d)(1), requires that all base metal flaws be cracks. Implanting a crack requires excavation of the base material on at least one side of the flaw. While this may be satisfactory for ferritic materials, it does not produce a useable axial flaw in austenitic materials because the

- 3 sound beam, which normally passes only through base material, must now travel through weld material on at least one side, producing an unrealistic flaw response. To resolve this issue, the POI program revised this paragraph to allow use of alternative flaw mechanisms under controlled conditions. For example, alternative flaws shall be limited to when implantation of cracks precludes obtaining an effective UT response, flaws shall be semi-elliptical with a tip width of less than or equal to 0.002-inches, and the remainder shall be alternative flaws.

Relief is requested to allow closer spacing of flaws provided they didn't interfere with detection or discrimination. The existing specimens used to date for qualification to the Tri-party agreement [Reference 1] have a flaw population density greater than allowed by the current ASME Code requirements. These samples have been used successfully for all previous qualifications under the Tri-party agreement program. To facilitate their use and provide continuity from the Tri-party agreement program to Supplement 11, the POI Program has merged the Tri-party test specimens into their weld overlay program. For example: the requirement for using IWA-3300 for proximity flaw evaluation in paragraph 1.1 (e)(1) was excluded, instead indications will be sized based on their individual merits; paragraph 1.1(d)(1) includes the statement that intentional overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the base metal flaws; paragraph 1.1 (e)(2)(a)(1) was modified to require that a base metal grading unit include at least 1 in. of the length of the overlaid weld, rather than 3 inches; paragraph 1.1 (e)(2)(a)(3) was modified to require sufficient unflawed overlaid weld and base metal to exist on all sides of the grading unit to preclude interfering reflections from adjacent flaws, rather than the 1-inch requirement of Supplement 11, paragraph 1.1 (e)(2)(b)(1), was modified to define an overlay fabrication grading unit as including the overlay material and the base metal-to-overlay interface for a length of at least 1 inch rather than the 6 square inch requirement of Supplement 11, and paragraph 1.1(e)(2)(b)(2), states that overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 inch at both ends, rather than around its entire perimeter.

Additionally, the requirement for axially oriented overlay fabrication flaws in paragraph 1.1 (e)( 1),

was excluded from the POI Program as an improbable scenario. Weld overlays are typically applied using automated gas tungsten arc welding techniques with the filler metal being applied in a circumferential direction. Because resultant fabrication induced discontinuities would also be expected to have major dimensions oriented in the circumferential direction axial overlay fabrication flaws are unrealistic.

The POI Program revised paragraph 2.0 allowing the overlay fabrication and base metal flaw tests to be performed separately. The requirement in paragraph 3.2(b), for reporting all extensions of cracking into the overlay, is omitted from the POI Program because it is redundant to the [root mean square] RMS calculations performed in paragraph 3.2(c), and its presence adds confusion and ambiguity to depth sizing as required by paragraph 3.2(c). This also makes the weld overlay program consistent with the Supplement 2 depth sizing criteria.

To avoid confusion, several instances of the term "cracks" or "cracking" were changed to the term "flaws" because of the use of alternative flaw mechanisms [Le., cracks are a type of flaw].

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

- 4 The proposed amended requirements of Supplement 11 for the qualification of personnel, procedures, and equipment will provide an alternative with an acceptable level of quality and safety.

3.5 Licensee's Basis for Proposed Alternative and NRC Staff Evaluation The United States nuclear utilities created the POI Program to implement performance demonstration requirements contained in Appendix VIII of Section XI of the ASME Code. The POI has developed into a program for qualifying equipment, procedures, and personnel for examinations of weld overlays in accordance with the UT criteria of Appendix VIII, Supplement

11. Prior to the Supplement 11 program, EPRI maintained a performance demonstration program for weld overlay qualification under the Tri-party Agreement (Reference 1). Instead of having two programs with similar objectives, the NRC staff recognized the POI Program for weld overlay qualifications as an acceptable alternative to the Tri-party Agreement (Reference 2).

The POI Program is routinely assessed by the NRC staff for consistency with the current ASME Code and proposed changes. The POI Program does not fully comport with the eXisting requirements of Supplement 11. POI representatives presented the differences at public meetings in which the NRC staff participated (References 3 and 4). The differences are in flaw locations within test specimens and fabricated flaw tolerances. The changes in flaw location permitted using test specimens from the Tri-party Agreement, and the changes in fabricated flaw tolerances provide UT acoustic responses similar to the responses associated with intergranular stress corrosion cracking. Based on the discussions at these public meetings, the NRC staff determined that the POI Program provides an acceptable level of quality and safety.

Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee requested relief to use the EPRI-POI program for implementation of Appendix VIII, Supplement 11, requirements. Specifically, relief is requested from Supplement 11, Paragraphs 1.1(b), 1.1(d)(1), 1.1 (e)(1), 1.1(e)(2),

1.1(e)(2)(a)(1), 1.1(e)(2)(a)(2), 1.1(e)(2)(a)(3), 1.1(e)(2)(b)(1), 1.1(e)(2)(b)(2), 1.1(e)(2)(b)(3),

1.1(f)(1), 1.1(f)(3), 1.1(f)(4), 2.2(d), 2.0, 2.1, 2.2(d), 2.3,3.1, 3.2(a) and 3.2(b). The proposed alternative will be implemented through use of the EPRI-POI Program weld overlay examination qualification requirements.

The licensee's basis for the proposed alternative and the NRC staff evaluation of the differences identified in the POI Program with Supplement 11 are as follows:

Paragraph 1.1 (b) of Supplement 11 states limitations to the maximum thickness for which a procedure may be qualified. The ASME Code states that, "The specimen set must include at least one specimen with overlay thickness within minus 0.1 O-inch to plus 0.25-inch of the maximum nominal overlay thickness for which the procedure is applicable." The ASME Code requirement addresses the specimen thickness tolerance for a single specimen set, but is confusing when multiple specimen sets are used. The POI proposed alternative states that, "the specimen set shall include specimens with overlay not thicker than 0.1 O-inch more than the minimum thickness, nor thinner than 0.25-inch of the maximum nominal overlay thickness for which the examination procedure is applicable." The proposed alternative provides clarification on the application of the tolerance. The tolerance is unchanged for a single specimen set; however, the proposed alternative clarifies the tolerance for multiple specimen sets by providing tolerances for both the minimum and maximum thicknesses. The proposed wording eliminates

- 5 confusion while maintaining the intent of the overlay thickness tolerance. Therefore, the NRC staff finds that this POI Program alternative maintains the intent of the Supplement 11, requirements and is acceptable.

Paragraph 1.1 (d)(1) requires that all base metal flaws be cracks. The POI determined that certain Supplement 11 requirements pertaining to location and size of cracks would be extremely difficult to embed in test specimens. For example, flaw implantation requires excavating a volume of base material to allow a pre-cracked coupon to be welded into this area.

This process would add weld material to an area of the specimen that typically consists of only base material, and could potentially make ultrasonic examination more difficult and not representative of actual field conditions. In an effort to satisfy the requirements, POI developed a process for fabricating flaws that exhibit crack-like reflective characteristics. Instead of all flaws being cracks, as required by Paragraph 1.1 (d)(1) of Supplement 11, the POI Program for weld overlays contain at least 70 percent cracks with the remainder being fabricated flaws exhibiting crack-like reflective characteristics. The fabricated flaws are semi-elliptical with tip widths of less than 0.002-inches. The licensee provided further information describing a revision to the POI Program alternative to clarify when real cracks, as opposed to fabricated flaws, will be used; "Flaws shall be limited to the cases where implantation of cracks produces spurious reflectors that are uncharacteristic of actual flaws." The NRC staff has reviewed the flaw fabrication process, compared the reflective characteristics between actual cracks and POI fabricated flaws, and found that the fabricated flaws for this application provide assurance that the POI Program meets the intent of the Supplement 11 requirement. Therefore, the NRC staff finds that the proposed alternative to the Supplement 11 requirement is acceptable.

Paragraph 1.1 (e)(1) requires that at least 20 percent but not less than 40 percent of the flaws shall be oriented within +/-20 degrees of the axial direction (of the piping test specimen). Flaws contained in the original base metal heat-affected zone satisfy this requirement; however, POI excludes axial fabrication flaws in the weld overlay material. POI has concluded that axial flaws in the overlay material are improbable because the overlay filler material is applied in the circumferential direction (parallel to the girth weld); therefore, fabrication anomalies would also be expected to have major dimensions in the circumferential direction. The NRC staff finds that this approach to implantation of fabrication flaws is reasonable for meeting the intent of the Supplement 11 requirement. Therefore, the NRC staff concludes that the POI's application of flaws oriented in the axial direction is acceptable.

Paragraph 1.1(e)(1) also requires that the rules of IWA-3300 shall be used to determine whether closely spaced flaws should be treated as single or multiple flaws. POI treats each flaw as an individual flaw and not as part of a system of closely spaced flaws. POI controls the flaws going into a test specimen set such that the flaws are free of interfering reflections from adjacent flaws. In some cases this permits flaws to be spaced closer than what is allowed for classification as a multiple set of flaws by IWA-3300, thus potentially making the performance demonstration more challenging than the existing requirement. Hence, the NRC staff concludes that POI's application for closely spaced flaws is acceptable.

Paragraph 1.1(e)(2) requires that specimens be divided into base metal and overlay grading units. The POI Program adds clarification with the addition of the word "fabrication" and ensures that flaw identification will not be masked by other flaws with the addition of the phrase "Flaws shall not interfere with ultrasonic detection or characterization of other flaws." POI's alternative

- 6 provides clarification and assurance that the flaws are identified. Therefore. the NRC staff finds that the POI alternative to the Supplement 11 requirement is acceptable.

Paragraph 1.1 (e)(2)(a)(1) requires that a base grading unit shall include at least three inches of the length of the overlaid weld, and the base grading unit includes the outer 25 percent of the overlaid weld and base metal on both sides. The POI Program reduced the criteria to one inch of the length of the overlaid weld and eliminated from the grading unit the need to include both sides of the weld. The proposed change permits the POI Program to continue using test specimens from the existing weld overlay program which have flaws on both sides of the welds.

These test specimens have been used successfully for testing the proficiency of personnel for over 16 years. The weld overlay qualification is designed to be a near-side (relative to the weld) examination, and it is improbable that a candidate would detect a flaw on the opposite side of the weld due to the sound attenuation and re-direction caused by the weld microstructure.

However. the presence of flaws on both sides of the original weld (outside the POI grading unit) may actually provide a more challenging examination, as candidates must determine the relevancy of these flaws, if detected. The NRC staff has determined that POI's use of the one inch length of the overlaid weld base grading unit and elimination from the grading unit the need to include both sides of the weld, as described in the POI Program alternative, is an acceptable alternative to the Supplement 11 requirements. Therefore, the NRC staff finds the proposed alternative acceptable.

Paragraph 1.1 (e)(2)(a)(2) requires when base metal cracking penetrates into the overlay material, that a portion of the base grading unit shall not be used as part of the overlay grading unit. The NRC staff finds that the POI Program adjusts for the changes in Paragraph 1.1 (e)(2)(a)(2) of Supplement 11 and conservatively states that when base metal flaws penetrate into the overlay material, no portion of it shall be used as part of the overlay fabrication grading unit. The NRC staff finds that the POI Program also provided clarification by the addition of the term "Haws" for "cracks" and the addition of "fabrication" to "overlay grading unit." The NRC staff concludes that the POI Program alternative provides clarification and conservatism, and therefore, is acceptable.

Paragraph 1.1 (e)(2)(a)(3) requires that for unflawed base grading units, at least one inch of unflawed overlaid weld and base metal shall exist on either side of the base grading unit. This is to minimize the number of false identifications of extraneous reflectors. The POI Program stipulates that unflawed overlaid weld and base metal exists on all sides of the grading unit and flawed grading units must be free of interfering reflections from adjacent flaws which addresses the same concerns as the ASME Code. Hence, the NRC staff concludes that POI's application of the variable flaw-free area adjacent to the grading unit meets the intent of the Supplement 11 requirements and is, therefore, acceptable.

Paragraph 1.1 (e)(2)(b)(1) requires that an overlay grading unit shall include the overlay material and the base metal-to-overlay interface of at least six square inches. The overlay grading unit shall be rectangular, with minimum dimensions of two inches. The POI Program reduces the base metal-to-overlay interface to at least one inch (in lieu of a minimum of two inches) and eliminates the minimum rectangular dimension. This change is necessary to allow use of existing examination specimens that were fabricated in order to meet NRC Generic Letter 88-01 (Tri-party Agreement, July 1984). This criterion may be more challenging to meet than that of the ASME Code because of the variability associated with the shape of the grading unit.

- 7 Therefore, the NRC staff concludes that POI's application of the grading unit is an acceptable alternative to the Supplement 11 requirements.

Paragraph 1.1 (e)(2)(b)(2) requires that unflawed overlay grading units shall be surrounded by unflawed overlay material and unflawed base metal-to-overlay interface for at least one inch around it's entire perimeter. The POI Program redefines the area by noting unflawed overlay fabrication grading units shall be separated by at least one inch of unflawed material at both ends and sufficient area on both sides to preclude interfering reflections from adjacent flaws.

The NRC staff determined that the relaxation in the required area on the sides of the specimens, while still ensuring no interfering reflections, may provide a more challenging demonstration than required by ASME Code because of the possibility of having a parallel flaw on the opposite side of the weld. Therefore, the NRC staff concludes that POI's application is an acceptable alternative to the Supplement 11 requirements.

Paragraph 1.1(e)(2)(b)(3) requirements are retained in the POI Program. In addition, the POI Program requires that initial procedure qualification contain three times the number of flaws required for a personal qualification. To qualify new values of essential variables, the equivalent of at least one personal qualification is required. The NRC staff concludes that POI's additions enhance the ASME Code requirements and are, therefore, acceptable because it provides more stringent qualification criteria.

Paragraph 1.1 (f)(1) requirements are retained in the POI Program, with the clarification change of the term "flaws" for "cracks." In addition, the POI Program includes the requirements that sizing sets shall contain a distribution of flaw dimensions to verify sizing capabilities. The POI Program also requires that initial procedure qualification contain three times the number of flaws required for a personal qualification. To qualify new values of essential variables, the equivalent of at least one personal qualification is required. The NRC staff concludes that POI's additions enhance the ASME Code requirements and are, therefore, acceptable because it provides more stringent qualification criteria.

Paragraphs 1.1(f)(3) and 1.1 (f)(4) requirements are clarified by the POI Program replacing the term "cracking" with "flaws" because of the use of alternative flaw mechanisms. The NRC staff concludes that this clarification in the POI Program meets the intent of the ASME Code requirements and is acceptable.

Paragraph 2.0 is silent on performance demonstrations for the weld metal and overlay fabrication. The POI Program addresses the two performance demonstrations by specifying that they may be performed separately. The POI Program adds clarity to the testing criteria without changing the requirement. Therefore, the NRC staff concludes that POI's clarification is an enhancement to ASME Code requirement and is acceptable.

Paragraphs 2.1 and 2.2(d) requirements are clarified by the POI Program by the addition of the terms "metal" and "fabrication". These terms were added to clarify the description of the grading units present in a specimen. Metal was added to base to read base metal and fabrication was added to overlay to read overlay fabrication. The NRC staff determined that the clarifications provide acceptable classification of the terms they are enhancing. Therefore, the NRC staff concludes that the POI Program meets the intent of the ASME Code requirements and is acceptable.

- 8 Paragraph 2.3 requires that, for depth sizing tests, 80 percent of the flaws shall be sized at a specific location on the surface of the specimen identified to the candidate. This requires detection and sizing tests to be performed separately. The POI revised the weld overlay program to allow sizing to be conducted either in conjunction with, or separately from, the flaw detection test. If performed in conjunction with detection and the detected flaws do not meet the Supplement 11 range criteria, additional specimens will be presented to the candidate with the regions containing flaws identified. Each candidate will be required to determine the maximum depth of the flaw in each region. For separate sizing tests, the regions of interest will also be identified and the maximum depth and length of each flaw in the region will similarly be determined. In addition, POI stated that grading units are not applicable to sizing tests, and that each sizing region will be large enough to contain the target flaw, but small enough such that candidates will not attempt to size a different flaw. The NRC staff has determined that the above clarification provides a basis for implementing sizing tests in a systematic, consistent manner that meets the intent of Supplement 11. Therefore, the NRC staff concludes that the POI method is acceptable.

Paragraph 3.1 requires that examination procedures, equipment and personnel (as a complete ultrasonic system) are qualified for detection or sizing of flaws, as applicable, when certain criteria are met. The POI Program allows procedure qualification to be performed separately from personnel and equipment qualification. Historical data indicate that, if ultrasonic detection or sizing procedures are thoroughly tested, personnel and equipment using those procedures have a higher probability of successfully passing a qualification test. In an effort to increase this passing rate, POI has elected to perform procedure qualifications separately in order to assess and modify essential variables that may affect overall system capabilities. For a procedure to be qualified, the POI Program requires three times as many flaws to be detected (or sized) as shown in Supplement 11 for the entire ultrasonic system. The personnel and equipment are still required to meet the Supplement 11 requirement. Therefore, the POI Program criteria exceed the ASME Code requirements for personnel, procedures, and equipment qualifications. The NRC staff concludes that the POI Program criteria are acceptable.

Paragraph 3.2(a) of Supplement 11 refers to term the "cracking" in the base metal and "flaws" within the same acceptance criteria. The POI Program changed the term from "cracking" to "flaws" for consistency in the acceptance criteria and uniformity within the proposed alternative.

The NRC staff concludes that POI's change adds clarity and meets the intent of the ASME Code requirements, and therefore, is acceptable.

Paragraph 3.2(b) requires that all extensions of base metal cracking into the overlay material by at least 0.1 O-inch are reported as being intrusions into the overlay material. The POI Program omits this criterion because of the difficulty in actually fabricating a flaw with a 0.1 O-inch minimum extension into the overlay, while still knowing the true state of the flaw dimensions.

However, the POI program requires that cracks be depth-sized to the tolerance specified in the ASME Code which is 0.125-inches. Since the ASME Code tolerance is close to the 0.1 O-inch value of Paragraph 3.2(b), any crack extending beyond 0.10-inch into the overlay material would be identified as such from the characterized dimensions. The NRC staff has determined that reporting of an extension in the overlay material is redundant for performance demonstration testing because of the flaw sizing tolerance. Therefore, the NRC staff concludes that POI's omission of highlighting a crack extending beyond 0.10-inch into the overlay material is acceptable.

- 9

4.0 CONCLUSION

The NRC staff has reviewed the licensee's submittal and determined that, in accordance with 10 CFR 50.55a(a)(3)(i), use of the POI Program to select paragraphs in Supplement 11 provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternative VEGP-ISI-ALT-01 is authorized for the third 10-year lSI interval at VEGP 1 and 2.

All other ASME Code,Section XI, requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.

5.0 REFERENCES

1.

The Tri-party Agreement is between NRC, EPRI, and the Boiling Water Reactor Owners Group (BWROG), "Coordination Plan for NRC/EPRI/BWROG Training and Qualification Activities of NDE (Nondestructive Examination) Personnel," July 3, 1984 (ADAMS Accession No. 8407090122).

2.

Letter from William H. Bateman to Michael Bratton, "Weld Overlay Performance Demonstration Administered by PDI as an Alternative for Generic Letter 88-01 Recommendations," January 15, 2002 (ADAMS Accession No. ML020160532).

3.

Memorandum from Donald G. Naujock to Terence Chan, "Summary of Public Meeting Held January 31 - February 2,2002, with PDI Representatives," March 22, 2002 (ADAMS Accession No. ML010940402).

4.

Memorandum from Donald G. Naujock to Terence Chan, "Summary of Public Meeting Held June 12 through June 14, 2001, with PDI Representatives," November 29, 2001 (ADAMS Accession No. ML013330156).

Principal Contributor: Don Naujock, NRR Date of Issuance:

July 6, 2009

M. Ajluni

- 2 If you have any questions, please contact the Project Manager, Donna Wright, at 301-415-1864.

Sincerely, IRA!

Melanie C. Wong, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos.: 50-424 and 50-425

Enclosure:

Safety Evaluation cc w/ encl: Distribution via Listserv DISTRIBUTION:

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