ML17292B295

Relief from the Requirements of the American Society of Mechanical Engineers Code (CAC No. MF8515; EPID L-2016-LLR-0003)

ML17292B295
Person / Time
Site:	Watts Bar
Issue date:	10/28/2017
From:	Undine Shoop Plant Licensing Branch II
To:	James Shea Tennessee Valley Authority
Robert Schaaf, NRR/DORL/LPL2-2
References
CAC MF8515, EPID L-2016-LLR-0003
Download: ML17292B295 (17)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 28, 2017 Mr. Joseph W. Shea Vice President, Nuclear Regulatory Affairs and Support Services Tennessee Valley Authority 1101 Market Street, LP 3R-C Chattanooga, TN 37402-2801

SUBJECT:

WATTS BAR NUCLEAR PLANT, UNIT 2-RELIEF FROM THE REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE (CAC NO. MF8515; EPID L-2016-LLR-0003)

Dear Mr. Shea:

By letter dated October 5, 2016, as supplemented by letter dated July 14, 2017, Tennessee Valley Authority (the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for relief from certain American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," Subarticle IWB-2200, "Preservice Examination," ASME Code Class 1, Table IWB-2500-1, and ASME Code Class 2, Table IWC-2500-1 requirements at Watts Bar Nuclear Plant, Unit 2.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (1 O CFR) 50.55a(g)(6)(i),

the licensee requested relief and to use alternative requirements (if necessary) for inservice inspection items on the basis that the Code requirement is impractical.

The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6)(i). Therefore, the NRC grants relief for the subject ASME Section XI Class 1 and 2 weld examinations for the preservice inspection period for Watts Bar, Unit 2, that ended on June 3, 2016, at initial turbine-generator synchronization after initial criticality.

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

If you have any questions, please contact the Project Manager, Robert Schaaf, at 301-415-6020 or by email to Robert.Schaaf@nrc.gov.

Docket No. 50-391

Enclosure:

Safety Evaluation cc w/

Enclosure:

Distribution via Listserv Sincerely, Undine Shoop, Chief Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 FOR RELIEF REQUEST WBN-2/PSl-1 I REVISION 1 EXAMINATIONS FOR PRESERVICE INSPECTION

1.0 INTRODUCTION

WATTS BAR NUCLEAR PLANT, UNIT 2 TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-391 By letter dated October 5, 2016, as supplemented by letter dated July 14, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML16293A334 and ML17206A192, respectively) Tennessee Valley Authority (the licensee) submitted Relief Request WBN-2/PSl-1, Revision 1, from the "essentially" 100 percent volumetric coverage requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, Rules for lnservice Inspection of Nuclear Power Plant Components for the preservice inspections (PSls) due to access limitations at the Watts Bar Nuclear Plant, Unit 2 (Watts Bar, Unit 2).

Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii),

the licensee requested relief from the "essentially 100 percent" volumetric coverage requirements of ASME Code Section XI for the subject welds on the basis that the Code requirement is impractical.

2.0 REGULATORY EVALUATION

The licensee has requested relief from ASME Code requirements pursuant to 10 CFR 50.55a(g)(5)(iii). Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in ASME Code Section XI to the extent practical, within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code, which was 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)(5)(iii) of 10 CFR, states in, part, that licensees may determine that conformance with certain ASME Code requirements is impractical and that the licensee shall notify the U.S. Nuclear Regulatory Commission (NRC or the Commission) and submit information in support of the determination. Determination of impracticality in accordance with this section must be based on the demonstrated limitations experienced when attempting to comply with the Code requirements during the inservice inspection (ISi) interval for which the Enclosure request is being submitted. Requests for relief made in accordance with this section must be submitted to the NRC no later than 12 months after the expiration of the initial 120-month inspection interval or subsequent 120-month inspection interval for which relief is sought.

Section 50.55a(g)(6)(i) of 10 CFR states that the Commission will evaluate determinations under paragraph (g)(5) of this section that Code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements as it determines are authorized by law and will not endanger life or property or the common defense and security and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

Based on the above, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the Commission to grant relief and impose such alternative requirements as it determines are authorized by law, will not endanger life or property or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

3.0 TECHNICAL EVALUATION

3.1 Licensee's Relief Request Code of Record The ASME Boiler and Pressure Vessel Code,Section XI, 2001 Edition through 2003 Addenda, was the code of record, as conditioned by 10 CFR 50.55a, for the PSI period for Watts Bar, Unit 2.

Components Covered by Relief Request The following tables list the subject Watts Bar, Unit 2, ASME Section XI, Code Class 1 and 2 welds that are addressed in Relief Request WBN-2/PSl-1, Revision 1.

T bl 1 C t B Fii f

It 85 70W Id a e. a egory -

nspec1on em e 5 Component ID System Diameter/Thickness Coverage Achieved Reactor Coolant System RCF-E1-2-SE (RCS) 28.94" ID I 2.33" 39%

RCF-G1-1-SE RCS 27.44" ID I 2.21" 30%

RCF-E2-2-SE RCS 28.94" ID I 2.33" 27%

RCF-G2-1-SE RCS 27.44" ID I 2.21" 31%

RCF-E3-2-SE RCS 28.94" ID I 2.33" 26%

RCF-G3-1-SE RCS 27.44" ID I 2.21" 29%

RCF-E4-2-SE RCS 28.94" ID I 2.33" 33%

RCF-G4-1-SE RCS 27.44" ID I 2.21" 28%

T bl 2 C t BJ I t"

It 8911 W Id a e. a egory -

nspec1on em e s Component ID System Diameter/Thickness Coveraqe Achieved RCF-C2-2 RCS 27.5" I 2.21" 75%

RCF-C3-2 RCS 27.5" I 2.21" 75%

RCF-0145-05 RCS 4" I 0.531" 90%

RCF-0145-0B RCS 4" I 0.531" 50%

RCF-G1-4 RCS 31" I 2.48" 75%

RCF-G2-4 RCS 31" I 2.48" 75%

RCF-G3-4 RCS 31" I 2.48" 75%

RCF-G4-4 RCS 31" I 2.48" 75%

RCS-011 RCS 6" I 0.719" 75%

RCS-018 RCS 6"/0.719" 75%

Reactor Vessel 2-085-W001-A5-1-0 (RV) 4" I 0.67" 73%

2-085-W001-E15-1-0 RV 4" I 0.67" 74%

2-085-W001-L 1-1-0 RV 4" I 0.67" 74%

2-085-W001-L 15-1-0 RV 4" I 0.67" 74%

2-085-W001-R11-1-0 RV 4" I 0.67" 74%

2-087B-W001-01 RCS 6.28" I 0.64 73%

2-087B-W001-02 RCS 6.28" I 0.64 74%

2-087B-W001-03 RCS 6.28" I 0.64 74%

2-087B-W001-04 RCS 6.28" I 0.64 74%

Residual Heat Removal RHRF-0031-04 System (RHRS) 14" I 1.250" 76%

RHRF-0031-13 RHRS 14" I 1.250" 83%

RHRF-0031-14 RHRS 10" I 1.00" 90%

RHRF-0032-12 RHRS 6"/0.719" 26%

RHRS-015 RHRS 10" I 1.00" 88%

Safety Injection SIF-0196-03 System (SIS) 10" I 1.00" 68%

SIF-0196-05 SIS 10" I 1.00" 73%

SIF-0196-06 SIS 10" I 1.00" 75%

SIF-0196-07 SIS 6" I 0.719" 73%

SIF-0196-10 SIS 10" I 1.00" 73%

SIF-0196-11 SIS 10" I 1.00" 75%

SIF-0197-03 SIS 1O"I1.00" 75%

SIF-0197-04 SIS 10" I 1.00" 74%

SIF-0197-05 SIS 10" I 1.00" 73%

SIF-0197-06 SIS 6" I 0.719" 69%

SIF-0197-08 SIS 10" I 1.00" 74%

SIF-0197-09 SIS 10" I 1.00" 74%

SIF-0197-11 SIS 6" I 0.719" 29%

SIF-D197-11A SIS 6"/0.719" 50%

SIF-0198-03 SIS 10" I 1.00" 75%

SIF-0198-04 SIS 10" I 1.00" 75%

SIF-0198-05 SIS 1O"I1.00" 75%

SIF-0198-06 SIS 6" I 0.719" 75%

Component ID System Diameter/Thickness CoveraQe Achieved SIF-0198-09 SIS 1O"I1.00" 50%

SIF-0198-10 SIS 1O"I1.00" 75%

SIF-0199-03 SIS 1O"I1.00" 57%

SIF-0199-05 SIS 10" I 1.00" 74%

SI F-0199-06 SIS 10" I 1.00" 75%

SIF-0199-07 SIS 6" I 0.719" 70%

SIF-0199-10 SIS 10" I 1.00" 73%

SIF-0199-11 SIS 10" I 1.00" 73%

SIF-0199-15 SIS 6" I 0.719" 61%

RCF-C4-1 RCS 27.44" ID I 2.21" 50%

RCF-C3-1 RCS 27.44" ID I 2.21" 50%

RCF-C2-1 RCS 27.44" ID I 2.21" 50%

RCF-Cl-1 RCS 27.44" ID I 2.21" 50%

RCF-Cl-2 RCS 27.5" ID I 2.21" 75%

RCF-C4-2 RCS 27.5" ID I 2.21" 62%

RCF-0145-03 RCS 4" I 0.531" 50%

RCF-0145-04 RCS 4" I 0.531" 50%

RCF-0145-09 RCS 4" I 0.531" 75%

T bl 3 C a e. ategory 8 JI f

It 89 22 W Id nspec1on em e s Component ID System Diameter/Thickness Coveraqe Achieved SIF-B-T076-06 SIS 1.5" I 0.281" 50%

SI F-B-T076-23 SIS 1.5" I 0.281" 50%

SIF-8-T077-01 SIS 1.5" I 0.281" 75%

SIF-8-T095-01 SIS 1.5" I 0.281" 50%

SI F-8-T097-12 SIS 1.5" I 0.281" 50%

SI F-8-T097-13 SIS 1.5" I 0.281" 50%

SIF-8-T107-04 SIS 1.5" I 0.281" 50%

SIF-8-T107-05 SIS 1.5" I 0.281" 50%

SIF-8-T107-26 SIS 1.5" I 0.281" 75%

SIF-8-T142-01 SIS 1.5" I 0.281" 49%

SI F-B-TI 42-24 SIS 1.5" I 0.281" 50%

SIF-8-TI 42-25 SIS 1.5" I 0.281" 50%

SIF-B-T154-01 SIS 1.5" I 0.281" 71%

SIF-0193-03 SIS 3" I 0.281" 70%

SIF-0193-08 SIS 2.5" I 0.375" 50%

SIF-0193-13 SIS 2.5" I 0.375" 50%

c 8 JI f

It 89 31 W Id Table 4:

ategory -

nspec1on em e s Component ID System Diameter/Thickness Coverage Achieved RCS-1-6 RCS 6" I 2.33" 50%

RCS-2-6 RCS 6" I 2.33" 50%

RCS-3-6 RCS 6" I 2.33" 50%

RCS-4-6 RCS 14" I 2.33 84%

RCS-P-1 RCS 14" I 2.33 68%

RCW-01 RCS 4"/2.21" 46%

HCW-02 RCS 4" I 2.21" 41%

T bl c

CF 11 t"

It CS 11 W Id a es:

ategory --

nspec1on em.

e s Component ID System Diameter/Thickness Coverage Achieved RHRF-0033-01 RHRS 8" I 0.906" 89%

SIF-0123-05 SIS 14" I 0.500 50%

SIF-0194-15 SIS 8" I 0.906 75%

SIF-0195-13 SIS 6

11 I 0.719 74%

Chemical and Volume Control CVCF-0007-12 System (CVCS) 8" I 0.322" 75%

T bl 6 C a e ategory CF 11 t"

It CS 21 W Id nspec1on em e s Component ID System Diameter/Thickness Coverage Achieved CVCF-A-T122-40 eves 2" I 0.343" 73%

CVCF-A-T122-41 eves 2" I 0.343" 73%

CVCF-0011-01 eves 4" I 0.237" 75%

SIF-B-T071-0S SIS 2" I 0.343" 75%

SIF-B-T071-09 SIS 2" I 0.343" 75%

SI F-B-T090-06 SIS 2" I 0.343" 75%

SI F-B-T090-07 SIS 2" I 0.343" 75%

SIF-0116-010 SIS 3" I 0.300" 75%

SIF-0116-06 SIS 4" I 0.337 86%

SIF-0118-02 SIS 4"/5.31" 75%

SIF-0118-13A SIS 4" I 5.31" 75%

SIF-0119-03 SIS 4" I 0.237" 75%

SIF-0120-10 SIS 4" I 0.237" 75%

T bl 7 C t CF 21 t"

It CS S1 W Id a e. a egory - -

nspec1on em e s Component ID System Diameter/Thickness Coverage Achieved Feedwater FWF-0212-04 System (FWS) 6" I 0.432" 84%

FWF-0213-03 FWS 6

11 I 0.432" 82%

c BAI t"

It 8111 W Id Table 8:

ategory -

nspec1on em e

Component ID System Dia./Thickness Coveraoe Achieved W02-03 Reactor 173" I 5.392" 88%

Pressure Vessel (RPV)

Com onent ID S stem Diameter/Thickness Covera e Achieved W08-09 RPV 173" I 7.30" 69%

T bl 10 C t B DI t"

It 83 90W Id a e. a egory -

nspec1on em e s Component ID System Diameter/Thickness Coverage Achieved N-15 RPV 31" I 10.98" 84%

N-16 RPV 31" I 10.98" 84%

N-17 RPV 31" I 10.98" 83%

N-18 RPV 31"/10.98" 83%

T bl 11 C t B DI t"

It 83 110 W Id a e. a egory -

nspec1on em e s Component ID System Diameter!Thickness Coverage Achieved WP-10 Pressurizer 14" I 3.35" 56%

(PZR)

WP-11 PZR 4" I 2.85" 66%

WP-12 PZR 6" I 2.85" 56%

WP-13 PZR 6" I 2.85" 59%

WP-14 PZR 6" I 2.85" 59%

WP-15 PZR 6" I 2.85" 60%

T bl 12 C t CAI t"

It C1 20 W Id a e. a egory -

nspec1on em e s Component ID System Diameter!Thickness CoveraQe Achieved BIT-2 Boron Injection 53" I 2.0" Head, 3.12" 61%

Tank (BIT)

Shell BIT-3 BIT 53" I 2.0" Head, 3.12" 61%

Shell RHRHX-1-2B Residual Heat 37" I 1.00" 73%

Removal Heat Exchanger (RHRHX)

RHRHX-2-2B RHRHX 37" I 1.00" 75%

SWIFLTR-62-96 Seal Water 4" I 0.674" 75%

Injection Filter T bl 13 C a e ategory CAI t"

It C1 30 W Id nspec1on em e

Component ID System Diameter!Thickness Coverage Achieved SG-2-3-2 Steam Generator 135" I 3.35" 89%

1. 2 T

I 14 C C Bl t"

It C2 21 W Id abe.

ategory -

nspec1on em e s Component ID System Diameter!Thickness Coverage Achieved BIT-1 BIT 6" I 2.0" 75%

BIT-4 BIT 6" I 2.0" 75%

T bl 15 C t CCI t"

It C310W Id a e. a egory -

nspec1on em e s Component ID System Diameter!Thickness CoveraQe Achieved BIT-5-IA BIT 53" I 0.625" 77%

BIT-6-IA BIT 53" I 0.625" 77%

BIT-7-IA BIT 53" I 0.625" 77%

BIT-8-IA BIT 53" I 0.625" 77%

Com onent ID S stem Diameter!Thickness Cevera e Achieved CCPH-2B-B-IA CVCS I Centrifugal 18" I 1" 83%

Char in Pum s 21.6" I 1" ASME Code Requirements ASME Section XI, Subarticle IWB-2200 requires preservice examination of essentially 100 percent of the pressure retaining welds in all Class 1 components. ASME Section XI, Subarticle IWB-2500 states that components shall be examined and tested as specified in Table IWB-2500-1, which also requires either a volumetric examination of essentially 100 percent of the weld volume or a surface examination of essentially 100 percent of the weld area. The specific item numbers from Table IWB-2500-1 are shown in Table 1.

ASME Code Class 2, Table IWC-2500-1 requires either a volumetric examination of essentially 100 percent of the weld volume or a surface examination of essentially 100 percent of the weld area. The specific item numbers from Table IWC-2500-1 are shown in Table 1.

The licensee invoked ASME Section XI, Code Case N-460, which determines that examination coverage of greater than 90 percent is considered acceptable for the essentially 100 percent Code-required coverage.

Licensee's Basis for Relief As stated by the licensee and summarized in the tables above, Tennessee Valley Authority was not able to achieve the required examination coverage (i.e., greater than 90 percent) for the subject ASME Section XI, Code Class 1 and 2 welds. The examination limitations described in the licensee's submittal are inherent in the components' design, geometry, and materials of construction that were acceptable as of the original construction permit date for Watts Bar, Unit 2, dated January 23, 1973.

ASME Section XI, IWB-2200 requires that preservice examinations include essentially 100 percent of the pressure retaining welds in all of ASME Code Class 1 components; therefore, the licensee was not able to select alternate Class 1 welds for examination.

Additionally, ASME Section XI, IWC-2200 requires that all preservice examinations required for those ASME Code Class 2 components initially selected for examination for ISi, and not exempt, shall be completed prior to initial plant startup as a PSI. Meeting these examination requirements would either require modifications to the plant to reposition or remove obstructions, or redesign or replacement of plant components where geometry is inherent to its design.

The licensee stated that the subject welds were examined to the maximum possible extent utilizing qualified/certified personnel, qualified equipment, and approved procedures to meet the PSI acceptance standards of ASME Section XI, 2001 Edition through 2003 Addenda. Surface conditioning of the piping welds was performed to the extent necessary to preclude a reduction in coverage associated with weld crowns, weld shrinkage, and/or surface roughness. The welds have not yet been in service and were developed to the construction code standards for installation. Additionally, the welds were subjected to ASME Code Section Ill hydrostatic pressure testing prior to initial startup.

The licensee requested that the proposed relief request be authorized pursuant to 1 O CFR 50.55a(g)(6)(i) for the PSI period for Watts Bar, Unit 2, that ended on June 3, 2016, at initial turbine-generator synchronization after initial criticality.

3.2

NRC Staff Evaluation

The NRC staff's review of the components in the relief request confirms for each weld that the designs of the welded components prevented the licensee from achieving the ASME Code-required coverage. In order to effectively increase the examination coverage, the welds would require design modifications or replacement. The licensee has shown that it is impractical to meet the ASME Code Section XI required preservice volumetric examination coverage for the subject replacement welds due to the geometry of the components. This would place a burden on the licensee. Each ASME Code Section XI weld inspection category and item number is evaluated below to determine if the inspections are sufficient for preservice examinations.

Category 8-A Inspection Item 81.11 Weld The licensee reported 88 percent total coverage of the weld by performing automated underwater ultrasonic testing (UT) exams utilizing phased array (PA) 60°-80° longitudinal waves (L), PA 40°-50° shear waves (S), PA 30°-60° L, and PA 50° L. Full examination of this weld was precluded due to the proximity of core support lugs to the weld. The accessible area of examination was limited to the sections of the weld directly below the support lugs. One hundred percent examination coverage of the weld regions between the lugs was achieved. No recordable indications were identified during the exams. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRC staff determined that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category 8-A Inspection Item 81.40 Weld The licensee initially reported 75 percent coverage of the weld obtained by performing 0° L, 45° S, and 60° S manual UT exams. Further examination was prevented due to the positioning of three lifting lugs and the proximity of the weld to the curvature of the flange. In the NRC staff's request for additional information (RAI), dated April 20, 2017 (ADAMS Accession No. ML17112A045), RAI 2 requested that the licensee define what scan directions (axial in or out, circumferential clockwise, or counterclockwise) of the W08-09 weld were associated with items 6 through 9 of the licensee's submittal {labeled only as directions 1 - 4), and to resubmit the figures highlighting the examination volume obtained with each scan and the obstructions preventing further examination. In its July 14, 2017, response, the licensee noted that scan directions 1, 2, 3, and 4, respectively, refer to axial from the flange surface, axial from the RPV head surface, circumferential (clockwise) around the exam volume, and circumferential (counter clockwise) around the exam volume. During the development of the licensee's response to the RAI, the licensee determined that the initially reported coverage contained errors, and the reported coverage has been changed to 69.3 percent. The recalculation was due to the addition of the 0° coverage and changes to the coverage obtained due to the lifting lug obstructions. Additionally, the licensee updated its figures to show what coverages were obtained with each scan, and no recordable identifications were found during the exams.

Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRC staff has determined that the licensee has performed the examinations to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category 8-D Inspection Item 83.90 Welds Examinations of welds N-15, N-16, N-17, and N-18 were performed parallel to the weld from the nozzle bore and both parallel and transverse to the weld from the inner diameter of the vessel wall. The licensee was able to achieve 100 percent coverage of all four welds from the nozzle bore examinations. Parallel and transverse examinations of the welds from the inner wall diameter were limited due to the proximity of the nozzle integral extension. Specifically, the integral extension limits the parallel wall exams to 67.6 percent coverage in all four welds, the transverse wall exams to 85.9 percent coverage in the N-15 and N-16 welds, and 82.3 percent coverage in the N-17 and N-18 welds. In total, the licensee was able to obtain 83.5 percent to 84.5 percent coverage of these welds by performing automated underwater UT exams utilizing PA 60°-80° L, PA 40°-50° S, PA 30°-60° L, PA 50° L, PA 5°-40° L, and PA 35°-45° S.

Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. No recordable indications were identified during the exams.

The NRC staff determined that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category 8-D Inspection Item 83.11 O Welds RAI 2 of the NRC staff's April 20, 2017, e-mail requested that the licensee provide scan direction reports for welds WP-11, WP-12, WP-13, WP-14, and WP-15 to define which scan directions (radial in or out, circumferential clockwise, or counterclockwise) were associated with items 6 through 9 of each applicable attachment to the licensee's submittal (labeled only as directions 1 - 4). The licensee reported that, for all of the welds, scan directions 1, 2, 3, and 4, respectively, refer to radial towards the nozzle, radial away from the nozzle, circumferential (clockwise) around the exam volume, and circumferential (counter clockwise) around the exam volume.

The NRC staff also requested clarification on how scans performed with different angles produced contradicting levels of coverage while exposed to the same limitations. First, Attachments 3 and 4 of Report Number R_P1283 for WP-11 indicated the same coverage was achieved using the 45° and 60° examinations when scanning radially away from the nozzle.

Secondly, Attachments 3 and 4 of Report Number R_P1282 for WP-12 note that greater coverage was obtained in both the radial in and radial out directions with the 60° scans than with the 45° scans. Lastly, Attachments 3 and 4 of Report Number R_P1280 for WP-15 indicated the same coverage was achieved using the 45° and 60° examinations when scanning radially towards the nozzle. In response to the inconsistencies, the licensee noted which angles/directions were incorrect and revised the final obtained coverages of the WP-11, WP-12, and WP-15 welds to 65.72 percent, 55.64 percent, and 60.4 percent, respectively. These changes are provided in further detail in the licensee's RAI response letter dated July 14, 2017.

The NRC staff requested that the licensee resubmit the figures highlighting the examination volume obtained with each scan and the obstructions preventing further examination. The revised figures submitted by the licensee provided more comprehensive detail of the coverage obtained during the exams and were in agreement with the revised coverage calculations reported. The licensee was able to obtain between 55 percent and 69 percent coverage of the welds by performing 0° L, 45° S, and 60° S manual UT exams. No recordable identifications were found during any of the exams. Further examination was prevented due to the configuration of the nozzle and heater penetrations. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRC staff finds that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category B-F Inspection Item B5.70 Welds The licensee was able to obtain between 26 percent and 39 percent coverage of the welds by performing 45° L UT exams. Further examination was prevented due to the configuration of the geometry of the welds. While the welds are described as "nozzle to safe end" welds in the letter dated October 5, 2016, the letter dated July 14, 2017, showed that these welds are nozzle-to-pipe or nozzle-to-elbow welds with no safe end. The weld metal used is ER308, which is an austenitic stainless steel, not a nickel alloy.

The examinations were largely through cast stainless steel using 1 megahertz (MHz) search units and were not spatially encoded. The inspections meet the requirements for the 2001 Edition through 2003 Addenda of ASME Code Section XI. Based on NUREG/CR-6933, "Assessment of Crack Detection in Heavy-Walled Cast Stainless Steel Piping Welds Using Advanced Low-Frequency Ultrasonic Methods," non-encoded inspections using 1 MHz transducers are not expected to be able to detect flaws with any reliability through cast stainless steel. Operational experience with Category B-F welds made with stainless steel weld material (as opposed to nickel alloys) has shown this category of welds to resist inservice degradation.

Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. These factors provide reasonable assurance of leaktightness and structural integrity for the current 10-year ISi interval.

Category B-J Inspection Item B9.11 Welds The licensee was able to obtain between 29 and 90 percent coverage of the welds by a variety of UT exams. Further examination was prevented due to the configuration of the components.

For the components constructed using wrought stainless steel, the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations. Similar to the Inspection Category B-F welds, welds RCF-C2-2, RCF-C3-2, RCF-C4-1, RCF-C3-1, RCF-C2-1, RCF-C1-2, RCF-C1-1, and RCF-C4-2 were primarily inspected through cast stainless steel. Based on NUREG/CR-6933, non-encoded inspections using 1 MHz transducers are not expected to be able to detect flaws with any reliability through cast stainless steel. Operational experience with similar welds in the operating fleet shows that they are not susceptible to inservice degradation in the first 10 years of operation. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. These factors provide reasonable assurance of leaktightness and structural integrity for the current 10-year ISi interval.

Category B-J Inspection Item 89.22 Welds The licensee was able to obtain between 49 and 75 percent coverage of the welds by performing UT exams. Further examination was prevented due to the configuration of the components. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Operational experience with similar welds in the operating fleet shows that they are not susceptible to inservice degradation in the first 1 O years of operation. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. These factors provide reasonable assurance of leaktightness and structural integrity for the current 10-year ISi interval. The examinations have been performed to the greatest possible extent using the applicable code of record and, therefore, are acceptable as baseline examinations.

Category B-J Inspection Item 89.31 Welds The licensee was able to obtain between 29 and 90 percent coverage of the welds by a variety of UT exams. Further examination was prevented due to the configuration of the components.

Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Similar to the Inspection Category B-F welds, welds RCS-1-6, RCS-2-6, RCS-3-6, RCS-4-6, and RCW-02 were primarily inspected through cast stainless steel. Based on NUREG/CR-6933, non-encoded inspections using 1 MHz transducers are not expected to be able to detect flaws with any reliability through cast stainless steel. Operational experience with similar welds in the operating fleet shows that they are not susceptible to inservice degradation in the first 10 years of operation. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. These factors provide reasonable assurance of leaktightness and structural integrity for the current 10-year ISi interval.

Category C-F-1 Inspection Item C5.11 Welds The licensee was able to obtain between 49 and 75 percent coverage of the welds by performing UT exams. Further examination was prevented due to the configuration of the components. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. The examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category C-F-1 Inspection Item C5.21 Welds The licensee was able to obtain between 49 and 75 percent coverage of the welds by performing UT exams. Further examination was prevented due to the configuration of the components. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. The examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category C-F-2 Inspection Item C5.51 Welds The licensee was able to obtain between 49 and 75 percent coverage of the welds by performing UT exams. Further examination was prevented due to the configuration of the components. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. The examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category C-A Inspection Item C1.20 Welds The licensee was able to obtain between 61 percent and 75 percent coverage of the welds by performing 0° L, 45° S, and 60° S and 60° refracted longitudinal manual UT exams. No recordable identifications were found during any of the exams, and further examination was prevented due to the configuration of the component and material limitations. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRC staff finds that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category C-A Inspection Item C1.30 Weld The licensee was able to obtain 89 percent coverage of the weld by performing 0° L, 45° S, and 60° S manual UT exams. Further examination was prevented due to the configuration of the component. No recordable indications were found during the examinations of the weld.

Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRC staff has determined that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category C-B Inspection Item C2.21 Welds The licensee was able to obtain 75 percent coverage of these welds performing 0° L, 45° S, and 60° refracted longitudinal manual UT exams. Further examination was prevented due to the proximity of the weld to the curvature of the nozzle. Examinations of the welds produced no recordable indications. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity.

Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRC staff has determined that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category C-C Inspection Item C3.1 O Weld The licensee was able to obtain 77 percent coverage of these welds utilizing manual penetrant test (PT) exams. Further examination was prevented due to four support legs that cover portions of the support pads, which are welded to the vessel. Examinations of the welds produced no recordable indications. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity.

Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRG staff has determined that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

Category C-C Inspection Item C3.30 Weld The licensee initially reported that 75 percent coverage was obtained utilizing manual PT exams. The staff requested in its RAI that the licensee provide the exam sheets detailing scan diagrams, the coverage obtained, coverage calculations, and obstructions inhibiting further examination. In its response, the licensee stated that the coverage for CCPH-28-B-IA had been recalculated to 82.6 percent. The licensee explained that the CCPH-28-B-IA weld is installed and mounted at four points to the pump case (assembly) and welded around the entire perimeter. The pump assembly is bolted to the pump pedestal at these same locations. Further examination of the weld is limited because the intersection of the pump assembly to the pump pedestal does not allow for examination of the bottom horizontal 6 inches of the weld. of the licensee's RAI response provided the schematic and dimensions of the weld, as well as the coverage calculations to confirm their new coverage value. The staff has reviewed the licensee's response and determined that the information provided is accurate, and the licensee performed the examinations to the maximum practical extent. No recordable indications were found in the examinations. Operating experience with preservice examinations with similar volumetric coverage on similar components using less-advanced ultrasonic inspection methods has proven to provide reasonable assurance of leaktightness and structural integrity. Additionally, there is reasonable assurance that any large flaws would have been detected by the Section Ill radiography previously performed on the welds. The NRG staff determined that the examinations have been performed to the greatest possible extent and, therefore, are acceptable as baseline examinations.

4.0 CONCLUSION

As set forth above, the NRG staff has determined that granting relief pursuant to 1 O CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest, given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

Accordingly, the NRG staff determines that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6)(i). Therefore, the NRG grants relief for the subject ASME Section XI Class 1 and 2 weld examinations for the PSI period for Watts Bar, Unit 2, which ended on June 3, 2016, at initial turbine-generator synchronization after initial criticality.

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

Principal Contributors: S. Cumblidge A. Young Date: October 28, 2017

SUBJECT:

WATTS BAR NUCLEAR PLANT, UNIT 2 - RELIEF FROM THE REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE (CAC NO. MF8515; EPID L-2016-LLR-0003) DATED OCTOBER 28, 2017 DISTRIBUTION:

PUBLIC LPL2-2 R/F RidsNrrDorlLpl2-2 Resource RidsNrrDmlrMphb Resource RidsNrrDmlrMvib Resource RidsNrrLABClayton Resource RidsNrrPMWattsBar Resource RidsRgn2MailCenter Resource RidsACRS_MailCTR Resource SCumblidge, NRR AYoung, NRR JBowen, OEDO ADAMS A ccess1on N ML172928295 o.:

• b >Y e-ma1 OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/PM* NRR/DORL/LPL2-2/LA NRR/DE/EPNB/BC*

NAME NJordan RSchaaf BClayton DAiiey (LRonewicz for)

DATE 10/24/2017 10/25/2017 10/25/2017 10/09/2017 OFFICE NRR/DORL/LPL2-2/BC NAME UShoop DATE 10/28/2017 OFFICIAL RECORD COPY