View source for RS-16-215, Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques in Lieu of Radiography

{{Adams
| number = ML16307A253
| issue date = 11/02/2016
| title = Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques in Lieu of Radiography
| author name = Helker D
| author affiliation = Exelon Generation Co, LLC
| addressee name = 
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000220, 05000237, 05000244, 05000249, 05000254, 05000265, 05000277, 05000278, 05000289, 05000317, 05000318, 05000352, 05000353, 05000373, 05000374, 05000410, 05000454, 05000455, 05000456, 05000457
| license number = DPR-018, DPR-019, DPR-025, DPR-029, DPR-030, DPR-044, DPR-050, DPR-053, DPR-056, DPR-063, DPR-069, NPF-011, NPF-018, NPF-037, NPF-039, NPF-066, NPF-069, NPF-072, NPF-077, NPF-085
| contact person = 
| case reference number = RS-16-215
| document type = Letter type:RS
| page count = 15
}}

=Text=
{{#Wiki_filter:Exelon Generation@                                         200 Exelon Way Kennett Square. PA 19348 www.exeloncorp.com 10 CFR 50.55a RS-16-215 November 2, 2016 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRG Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-37 and NPF-66 N RC Docket Nos. STN 50-454 and STN 50-455 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 N RC Docket Nos. 50-317 and 50-318 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRG Docket Nos. 50-237 and 50-249 LaSalle County Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRG Docket Nos. 50-373 and 50-374 Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRG Docket Nos. 50-352 and 50-353 Nine Mile Point Nuclear Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-63 and NPF-69 NRG Docket Nos. 50-220 and 50-41 O Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRG Docket Nos. 50-277 and 50-278 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and DPR-30 N RC Docket Nos. 50-254 and 50-265

U.S. Nuclear Regulatory Commission Relief Request Encoded PAUT in lieu of Radiography November 2, 2016 Page 2 R. E. Ginna Nuclear Power Plant Renewed Facility Operating License No. DPR-18 NRG Docket No. 50-244 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 NRG Docket No. 50-289

==Subject:==
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography Pursuant to 10 CFR 50.55a(z)(1 ), Exelon Generation Company, LLC (Exelon) requests Nuclear Regulatory Commission (NRG) approval of a proposed alternative to radiography performed on construction welds in ferritic piping. American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel (B&PV) Section Ill requires that certain ferritic circumferential pipe weld joints be examined using radiographic examination techniques to satisfy nondestructive examination requirements. Exelon requests approval to use encoded Phased Array Ultrasonic Examination Techniques (PAUT) as an alternative to radiographic examination. Exelon considers the proposed alternative would provide an acceptable level of quality and safety. The supporting basis for this request is contained in the attachment to this letter.
Exelon requests approval of the proposed alternative to support fall 2017 refueling outages. Approval is requested by October 1, 2017.
The basis for this request is provided in the Attachment. There are no commitments contained in this submittal.
If you have any questions regarding this submittal, please contact Stephanie Hanson at 610-765-5143.
Respectfully, David P. Helker Manager - Licensing and Regulatory Affairs Exelon Generation Company, LLC

U.S. Nuclear Regulatory Commission Relief Request Encoded PAUT in lieu of Radiography November 2, 2016 Page 3

==Attachment:==
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography cc:     Regional Administrator - NRC Region I Regional Administrator - NRC Region Ill NRC Senior Resident Inspector - Braidwood Station NRC Senior Resident Inspector - Byron Station NRC Senior Resident Inspector - Calvert Cliffs Nuclear Power Plant NRC Senior Resident Inspector - Dresden Nuclear Power Station NRC Senior Resident Inspector - LaSalle County Station NRC Senior Resident Inspector - Limerick Generating Station NRC Senior Resident Inspector - Nine Mile Point Nuclear Station NRC Senior Resident Inspector - Peach Bottom Atomic Power Station NRC Senior Resident Inspector - Quad Cities Nuclear Power Station NRC Senior Resident Inspector - R.E. Ginna Nuclear Power Plant NRC Senior Resident Inspector - Three Mile Island Nuclear Station, Unit 1 NRC Project Manager - Braidwood Station NRC Project Manager - Byron Station NRC Project Manager - Calvert Cliffs Nuclear Power Plant NRC Project Manager - Dresden Nuclear Power Station NRC Project Manager - LaSalle County Station NRC Project Manager - Limerick Generating Station NRC Project Manager - Nine Mile Point Nuclear Station NRC Project Manager - Peach Bottom Atomic Power Station NRC Project Manager - Quad Cities Nuclear Power Station NRC Project Manager - R.E. Ginna Nuclear Power Plant NRC Project Manager - Three Mile Island Nuclear Station, Unit 1 S. T. Gray, State of Maryland A. L. Peterson, NYSERDA Illinois Emergency Management Agency - Division of Nuclear Safety R. R. Janati - Bureau of Radiation Protection, Commonwealth of Pennsylvania

ATTACHMENT Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 1 of 11)
: 1. ASME Code Component(s) Affected:
All American Society of Mechanical Engineers (ASME), Boiler & Pressure Vessel (B&PV)
Code, Section XI, ISi ferritic piping butt welds requiring radiography during repair/replacement activities.

===2. Applicable Code Edition and Addenda===
PLANT            INTERVAL         EDITION               START                END Braidwood Station,                 2001 Edition, through   July 29, 2008      July 28, 2018 Third Units 1 and 2                      2003 Addenda       October 17, 2008   October 16, 2018 Byron Station,                  2007 Edition, through Fourth                            July 16, 2016      July 15, 2025 Units 1 and 2                      2008 Addenda Calvert Cliffs Nuclear Power Fourth        2004 Edition      October 10, 2009     June 30, 2019 Plant, Units 1 and 2 Dresden Nuclear Power                 2007 Edition, through Fifth                          January 20, 2013   January 19, 2023 Station, Units 2 and 3                  2008 Addenda 2007 Edition, through LaSalle Units 1 and 2     Fourth                           October 1, 2017  September 30, 2027 2008 Addenda Limerick Generating Station,             2007 Edition, through Fourth                          February 1, 2017   January 31, 2027 Units 1 and 2                      2008 Addenda Nine Mile Point Nuclear Fourth        2004 Edition       August23,2009      August22,2019 Station, Unit 1 Nine Mile Point Nuclear Third        2004 Edition         April 5, 2008     June 15, 2018 Station, Unit 2 Peach Bottom Atomic Power                2001 Edition, through Fourth                          November 5, 2008 December 31, 2018 Station, Units 2 and 3                 2003 Addenda Quad Cities Nuclear Power               2007 Edition, through Fifth                             April 2, 2013      April 1, 2023 Station, Units 1 and 2                 2008 Addenda R. E. Ginna Nuclear Power     Fifth        2004 Edition       January 1, 201 O December 31, 2019 Plant Three Mile Island Nuclear Fourth        2004 Edition        April 20, 2011     April 19, 2022 Station, Unit 1

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 2 of 11)

===3. Applicable Code Requirement===
10 CFR 50.55a(b)(2)(xx)(B) requires that "The NDE provision in IWA-4540(a)(2) of the 2002 Addenda of Section XI must be applied when performing system leakage tests after repair and replacement activities performed by welding or brazing on a pressure retaining boundary using the 2003 Addenda through the latest edition and addenda incorporated by reference in paragraph (a)(1 )(ii) of this section." IWA-4540(a)(2) of the 2002 Addenda of Section XI requires that the nondestructive examination method and acceptance criteria of the 1992 Edition or later of Section Ill be met prior to return to service in order to perform a system leakage test in lieu of a system hydrostatic test. The examination requirements for ASME Section Ill, circumferential butt welds are contained in the ASME Code, Section Ill, subarticle NB-5200, NC-5200 and ND-5200. The acceptance standards for radiographic examination are specified in subarticle NB-5300, NC-5300 and ND-5300.

===4. Reason for Request===
Replacement of piping is periodically performed in support of the Flow Accelerated Corrosion (FAG) program as well as other repair and replacement activities. The use of encoded Phased Array Ultrasonic Examination Techniques (PAUT) in lieu of radiography (RT) to perform the required examinations of the replaced welds would eliminate the safety risk associated with performing RT, which includes the planned exposure and the potential for accidental personnel exposure. PAUT minimizes the impact on other outage activities normally involved with performing RT such as limited access to work locations and the need to control system fill status because RT would require a line to remain fluid empty in order to obtain adequate examination sensitivity and resolution. In addition, encoded PAUT has been demonstrated to be adequate for detecting and sizing critical flaws.
Exelon Generation Company, LLC (Exelon) requests approval of this proposed alternative to support anticipated piping repair and replacement activities starting in the fall 2017 outage season. The duration of the proposed alternative request is for the remainder of the ISi Interval for the plants defined in Section 2 of this relief request.
: 5. Proposed Alternative and Basis for Use:
Exelon is proposing the use of encoded PAUT in lieu of the code-required RT examinations for ASME ferritic piping repair/replacement welds. Similar techniques are being used throughout the nuclear industry for examination of dissimilar metal welds and overlaid welds, as well as other applications including ASME 831.1 piping replacements. This proposed alternative request includes requirements that provide an acceptable level of quality and safety that satisfy the requirements of 10 CFR 50.55a(z)(1 ). The capability of the alternative technique is comparable to the examination methods documented in the ASME Code Sections Ill, VIII, and IX, and associated code cases (References 1, 3, 5, 6, 8, 9, 1o, 11, 12 and 13) related to using ultrasonic examination techniques for weld acceptance. The examinations will be performed using personnel and procedures qualified with the requirements of Section 5.1 below.
The electronic data files for the PAUT examinations will be stored as part of the archival-quality records. In addition, hard copy prints of the data will also be included as part of the PAUT examination records to allow viewing without the use of hardware or software.

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 3 of 11) 5.1 Proposed Alternative Exelon is proposing to perform encoded PAUT examination techniques using demonstrated procedures, equipment and personnel in accordance with the process documented below:
(1)  The welds to be examined shall meet the surface conditioning requirements of the demonstrated ultrasonic procedure.
(2)  The welds to be examined shall be conditioned such that transducers properly couple with the scanning surface with no more than a 1/32 in. (0.8 mm) gap between the search unit and the scanning surface.
(3)  The ultrasonic examination shall be performed with equipment, procedures, and personnel qualified by performance demonstration.
(4)  The examination volume shall include 100% of the weld volume and the weld-to-base-metal interface.
(a) Angle beam examination of the complete examination volume for fabrication flaws oriented parallel to the weld joint shall be performed.
(b)   Angle beam examination for fabrication flaws oriented transverse to the weld joint shall be performed to the extent practical. Scan restrictions that limit complete coverage shall be documented.
(c}   A supplemental straight beam examination shall be performed on the volume of base metal through which the angle beams will travel to locate any reflectors that can limit the ability of the angle beam to examine the weld. Detected reflectors that may limit the angle beam examination shall be recorded and evaluated for impact on examination coverage. The straight beam examination procedure, or portion of the procedure, is required to be qualified in accordance with ASME Section V, Article 4 and may be performed using non-encoded techniques.
(5} All detected flaw indications from (4)(a} and (4)(b} above shall be considered planar flaws and compared to the preservice acceptance standards for volumetric examination in accordance with IWB-3000, IWC-3000 or IWD-3000. Preservice acceptance standards shall be applied. Analytical evaluation for acceptance of flaws in accordance with IWB-3600, IWC-3600 or IWD-3600 is permitted for flaws that exceed the applicable acceptance standards and are confirmed by surface or volumetric examination to be non-surface connected.
(6) Flaws exceeding the applicable acceptance standards and when analytical evaluation has not been performed for acceptance, shall be reduced to an acceptable size or removed and repaired, and the location of the repair shall be reexamined using the same ultrasonic examination procedure that detected the flaw.

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 4 of 11)
(7)  The ultrasonic examination shall be performed using encoded UT technology that produces an electronic record of the ultrasonic responses indexed to the probe position, permitting off-line analysis of images built from the combined data.
(a)    Where component configuration does not allow for effective examination for transverse flaws, (e.g., pipe-to-valve, tapered weld transition, weld shrinkage, etc.) the use of non-encoded UT technology may be used for transverse flaws.
The basis for the non-encoded examination shall be documented.
(8)  A written ultrasonic examination procedure qualified by performance demonstration shall be used. The qualification shall be applicable to the scope of the procedure, e.g., flaw detection and/or sizing (length or through-wall height), encoded or non-encoded, single and/or dual side access, etc. The procedure shall:
(a)    contain a statement of scope that specifically defines the limits of procedure applicability (e.g., minimum and maximum thickness, minimum and maximum diameter, scanning access);
(b)    specify which parameters are considered essential variables, and a single value, a range of values or criteria for selecting each of the essential variables; (c)    list the examination equipment, including manufacturer and model or series; (d)    define the scanning requirements; such as beam angles, scan patterns, beam direction, maximum scan speed, extent of scanning, and access; (e)    contain a description of the calibration method (i.e., actions required to ensure that the sensitivity and accuracy of the signal amplitude and time outputs of the examination system, whether displayed, recorded, or automatically processed, are repeated from examination to examination);
(f)     describe the method and criteria for discrimination of indications (e.g.,
geometric indications versus indications of flaws and surface versus subsurface indications); and (g)    describe the surface preparation requirements.
(9)  Performance demonstration specimens shall conform to the following requirements:
(a)    The specimens shall be fabricated from ferritic material with the same inside surface cladding process, if applicable, with the following exceptions:
(i) Demonstration with shielded metal arc weld (SMAW) single-wire cladding is transferable to multiple-wire or strip-clad processes; (ii) Demonstration with       multiple-wire or strip-clad process is considered equivalent but is not transferable to SMAW type cladding processes.
(b)    The demonstration specimens shall contain a weld representative of the joint to be ultrasonically examined, including the same welding processes.

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 5 of 11)
(c)  The demonstration set shall include specimens not thicker than 0.1 in. (2.5 mm) more than the minimum thickness, nor thinner than 0.5 in. (13 mm) less than the maximum thickness for which the examination procedure is applicable.
The demonstration set shall include the minimum, within 112 inch of the nominal pipe size (NPS), and maximum pipe diameters for which the examination procedure is applicable. If the procedure is applicable to outside diameter (O.D.) piping of 24 in. (600 mm) or larger, the specimen set must include at least one specimen 24 in. O.D. (600 mm) or larger but need not include the maximum diameter.
(d) The demonstration specimen scanning and weld surfaces shall be representative of the surfaces to be examined.
(e) The demonstration specimen set shall include geometric conditions that require discrimination from flaws (e.g., counterbore, weld root conditions, or weld crowns) and limited scanning surface conditions for single-side access, when applicable.
(f) The demonstration specimens shall include both planar and volumetric fabrication flaws (e.g., lack of fusion, crack, incomplete penetration, slag inclusions) representative of the welding process or processes of the welds to be examined. The flaws shall be distributed throughout the examination volume.
(g)  Specimens shall be divided into flawed and unflawed grading units.
(i) Flawed grading units shall be the actual flaw length, plus a minimum of 0.25 in. (6 mm) on each end of the flaw. Unflawed grading units shall be at least 1 in. (25 mm). *
(ii) The number of unflawed grading units shall be at least 1-1/2 times the number of flawed grading units.
(h)  Demonstration specimen set flaw distribution shall be as follows:
(i) For thickness greater than 0.50 in. (13 mm); at least 20% of the flaws shall be distributed in the outer third of the specimen wall thickness, at least 20% of the flaws shall be distributed in the middle third of the specimen wall thickness and at least 40% of the flaws shall be distributed in the inner third of the specimen wall thickness. For thickness 0.50 in. (13mm) and less, at least 20% of the flaws shall be distributed in the outer half of the specimen wall thickness and at least 40% of the flaws shall be distributed in the inner half of the specimen wall thickness.
(ii) At least 30% of the flaws shall be classified as surface planar flaws in accordance with IWA-3310. At least 40% of the flaws shall be classified as subsurface planar flaws in accordance with IWA-3320.

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 6 of 11)
(iii) At least 50% of the flaws shall be planar flaws, such as lack of fusion, incomplete penetration, or cracks. At least 20% of the flaws shall be volumetric flaws, such as slag inclusions.
(iv)The flaw through-wall heights shall be based on the applicable acceptance standards for volumetric examination in accordance with IWB-3400, IWC-3400 or IWD-3400. At least 30% of the flaws shall be classified as acceptable planar flaws, with the smallest flaws being at least 50% of the maximum allowable size based on the applicable a/I aspect ratio for the flaw. Additional smaller flaws may be included in the specimens to assist in establishing a detection threshold, but shall not be counted as a missed detection if not detected. At least 30% of the flaws shall be classified as unacceptable in accordance with the applicable acceptance standards. Welding fabrication flaws are typically confined to a heigtt of a single weld pass. Flaw through- wall height distribution shall range from approximately one to four weld pass thicknesses, based on the welding process used.
(v) If applicable, at least two flaws, but no more than 30% of the flaws, shall be oriented perpendicular to the weld fusion line and the remaining flaws shall be circumferentially oriented.
(vi) For demonstration of single-side-access capabilities, at least 30% of the flaws shall be located on the far side of the weld centerline and at least 30%
of the planar flaws shall be located on the near side of the weld centerline.
The remaining flaws shall be distributed on either side of the weld.
(10) Ultrasonic examination procedures shall be qualified by performance demonstration in accordance with the following requirements.
(a) The procedure shall be demonstrated using either a blind or a non-blind demonstration.
(b) The non-blind performance demonstration is used to assist in optimizing the examination procedure. When applying the non-blind performance demonstration process, personnel have access to limited knowledge of specimen flaw information during the demonstration process. The non-blind performance demonstration process consists of an initial demonstration without any flaw information, an assessment of the results and feedback on the performance provided to the qualifying candidate. After an assessment of the initial demonstration results, limited flaw information may be shared with the candidate as part of the feedback process to assist in enhancing the examination procedure to improve the procedure performance. In order to maintain the integrity of the specimens for blind personnel demonstrations, only generalities of the flaw information may be provided to the candidate. Procedure modifications or enhancements made to the procedure, based on the feedback process, shall be applied to all applicable specimens based on the scope of the changes.

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 7 of 11)
(c) Objective evidence of a flaw's detection, length and through-wall height sizing, in accordance with the procedure requirements, shall be provided to the organization administering the performance demonstration.
(d) The procedure demonstration specimen set shall be representative of the procedure scope and limitations (e.g., thickness range, diameter range, material, access, surface condition).
(e) The demonstration set shall include specimens to represent the minimum and maximum diameter and thickness covered by the procedure. If the procedure spans a range of diameters and thicknesses, additional specimens shall be included in the set to demonstrate the effectiveness of the procedure throughout the entire range.
(f) The procedure demonstration specimen set shall include at least 30 flaws and shall meet the requirements of (9) above.
(g) Procedure performance demonstration acceptance criteria (i) To be qualified for flaw detection, all flaws in the demonstration set that are not I es s than 50% of the maximum allowable size, based on the applicable a// aspect ratio for the flaw, shall be detected. In addition, when performing blind procedure demonstrations, no more than 20% of the non-flawed grading units may contain a false call. Any non-flaw condition (e.g., geometry) reported as a flaw shall be considered a false call.
(ii) To be qualified for flaw length sizing, the root mean square (RMS) error of the flaw lengths estimated by ultrasonics, as compared with the true lengths, shall not exceed 0.25 in. (6 mm) for diameters of NPS 6.0 in.
(DN150) and smaller, and 0.75 in. (18 mm) for diameters greater than NPS 6.0 in. (DN150).
(iii) To be qualified for flaw through-wall height sizing, the RMS error of the flaw through-wall heights estimated by ultrasonics, as compared with the true through-wall heights, shall not exceed 0.125 in. (3 mm).
(iv) RMS error shall be calculated as follows:
RMS=
n

10 CFR 50.SSa RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 8 of 11) where:
m; = measured flaw size n = number of flaws measured t; =true flaw size (h)   Essential variables may be changed during successive personnel performance demonstrations. Each examiner need not demonstrate qualification over the entire range of every essential variable.
(11) Ultrasonic examination personnel shall be qualified in accordance with IWA- 2300. In addition, examination personnel shall demonstrate their capability to detect and size flaws by performance demonstration using the qualified procedure in accordance with the following requirements:
(a) The personnel performance demonstration shall be conducted in a blind fashion (flaw information is not provided).
(i) The demonstration specimen set shall contain at least 1O flaws and shall meet the flaw distribution requirements of (9)(h) above, with the exception of (9)(h)(v). When applicable, at least one flaw, but no more than 20% of the flaws, shall be oriented perpendicular to the weld fusion line and the remaining flaws shall be circumferentially oriented.
(b) Personnel performance demonstration acceptance criteria:
(i) To be qualified for flaw detection, personnel performance demonstration shall meet the requirements of the following table for both detection and false calls. Any non-flaw condition (e.g., geometry) reported as a flaw shall be considered a false call.

10 CFR 50.SSa RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 9 of 11)
Performance Demonstration Detection Test Acceptance Criteria Detection Test Acceptance               False Call Test Acceptance Criteria                              Criteria No. of            Maximum No. of Flawed             Minimum Unflawed            Number of Grading Units         Detection Criteria Grading Units         False Calls 10                 8                  15                   2 11                 9                  17                   3 12                 9                  18                   3 13                 10                 20                   3 14                 10                 21                   3 15                 11                 23                   3 16                 12                 24                   4 17                 12                 26                   4 18                 13                 27                   4 19                 13                 29                   4 20                  14                 30                   5 Note 1: Flaws ~ 50% of the maximum allowable size, based on the applicable alt aspect ratio for the flaw.
(ii)   To be qualified for flaw length sizing, the RMS error of the flaw lengths estimated by ultrasonics, as compared with the true lengths, shall not exceed 0.25 in. (6 mm) for NPS 6.0 in. (DN150) and smaller, and 0.75 in. (18 mm) for diameters larger than NPS 6.0 in. (DN150).
(iii)  To be qualified for flaw through-wall height sizing, the RMS error of the flaw through-wall heights estimated by ultrasonics, as compared with the true through-wall heights, shall not exceed 0.125 in. (3 mm).
(12) Documentation of the qualifications of procedures and personnel shall be maintained. Documentation shall include identification of personnel, NOE procedures, equipment and specimens used during qualification, and results of the performance demonstration.
(13) The pre-service examinations will be performed per ASME Section XI (Reference 4).

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 1O of 11) 5.2 Basis for use The overall basis for this proposed alternative is that encoded PAUT is equivalent or superior to RT for detecting and sizing critical (planar) flaws. In this regard, the basis for the proposed alternative was developed from numerous codes, code cases, associated industry experience, articles, and the results of RT and encoded PAUT examinations. The examination procedure and personnel performing examinations are qualified using representative piping conditions and flaws that demonstrate the ability to detect and size flaws that are both acceptable and unacceptable to the defined acceptance standards. The demonstrated ability of the examination procedure and personnel to appropriately detect and size flaws provides an acceptable level of quality and safety alternative as allowed by 10 CFR 50.55a(z)(1 ).
: 6. Duration of Proposed Alternative:
This relief request will be applied for the duration of the inservice inspection intervals defined in Section 2 of this relief request.
: 7. Precedence:
: 1. Oconee Request for Relief No. 2006-0N-01, dated February 2, 2006, requested an alternative for examination of butt welds between the Pressurizer Level and Sample Tap nozzles and their respective Safe Ends. The reason for the request was based on the difficulty to perform the code required radiography. The alternative was to perform ultrasonic examination per similar requirements to Code Case N-659-1.
(ADAMS Accession No. ML060450464)
: 2. Wolf Creek 10 CFR 50.55a Request ET 06-0029, dated September 1, 2006, requested an alternative for examination of main steam and feedwater piping welds being replaced due to flow assisted corrosion. The reason for the request was based on the acceptability of the proposed ultrasonic examination alternative process, radiation exposure reduction, outage costs and duration, and radiography exposure risk. (ADAMS Accession No. ML062500093)
: 3. Palo Verde Nuclear Generating Station Relief Request 48, dated August 1, 2012 (ADAMS Accession No. ML12229A046). NRG approval dated April 12, 2013 (ADAMS Accession No. ML13091A177).
: 4. Millstone Power Station Unit 2 Alternative Request RR-04-16, dated August 1, 2013 (ADAMS Accession No. ML13220A019). NRG approval dated April 4, 2014 (ADAMS Accession No. ML14091A973).
: 5. Millstone Power Station Units 2 and 3 Alternative Requests RR-04-21 and IR-3-25, dated October 6, 2014 (ADAMS Accession No. ML14283A128). NRG approval dated September 21, 2015 (ADAMS Accession No. ML15257A005).

10 CFR 50.55a RELIEF REQUEST:
Proposed Alternative for the Use of Encoded Phased Array Ultrasonic Examination Techniques In Lieu of Radiography (Page 11 of 11)
: 8. 

==References:==
: 1. ASME Section Ill Code Case N-659-2, "Use of Ultrasonic Examination in Lieu of Radiography for Weld Examination Section Ill, Divisions 1 and 3," dated June 9, 2008.
: 2. Pacific Northwest National Laboratory Report PNNL-19086, "Replacement of Radiography with Ultrasonics for the Nondestructive Inspection of Welds -
Evaluation of Technical Gaps -An Interim Report," dated April 2010.
: 3. ASME 831.1, Case 168, "Use of Ultrasonic Examination in Lieu of Radiography for 831. 1 Application," dated June 1997.
: 4. ASME Section XI Code Editions and Addenda applicable to every site.
: 5. ASME Section Ill, Code Case N-818, "Use of Analytical Evaluation approach for Acceptance of Full Penetration Butt Welds in Lieu of Weld Repair," dated December 6, 2011.
: 6. ASME Code Case 2235-9, "Use of Ultrasonic Examination in Lieu of Radiography Section I, Section VIII, Divisions 1 and 2, and Section XII," dated October 11, 2005.
: 7. Journal of Pressure Vessel Technology, "Technical Basis for ASME Section VIII Code Case 2235 on Ultrasonic Examination of Welds in Lieu of Radiography;" Rana, Hedden, Cowfer and Boyce, Volume 123, dated August 2001.
: 8. ASME Code Case 2326, "Ultrasonic Examination in Lieu of Radiographic Examination for Welder Qualification Test Coupons Section IX," dated January 20, 2000.
: 9. ASME Code Case 2541, "Use of Manual Phased Array Ultrasonic Examination Section V," pated January 19, 2006.
: 10. ASME Code Case 2558, "Use of Manual Phased Array E-Scan Ultrasonic Examination per Article 4 Section V," dated December 30, 2006.
: 11. ASME Code Case 2599, "Use of Linear Phased Array E-Scan Ultrasonic Examination per Article 4 Section V," dated January 29, 2008.
: 12. ASME Code Case 2600, "Use of Linear Phased Array S-Scan Ultrasonic Examination Per Article 4 Section V," dated January 29, 2008.
: 13. ASME Code Case N-713, "Ultrasonic Examination in Lieu of Radiography Section XI, Division 1," dated November 10, 2008.}}