View source for WBL-21-028, Cycle 3 Steam Generator Tube Inspection Report

{{Adams
| number = ML21130A040
| issue date = 05/10/2021
| title = Cycle 3 Steam Generator Tube Inspection Report
| author name = Williams A
| author affiliation = Tennessee Valley Authority
| addressee name = 
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000391
| license number = NPF-096
| contact person = 
| case reference number = WBL-21-028
| document type = Inservice/Preservice Inspection and Test Report, Letter type:WBL
| page count = 18
}}

=Text=
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TEN.NE.SSEE VALLEY AUTHORITY Post Office Box 2000, Spring City, Tennessee 37381 WBL-21-028 May 10, 2021 10 CFR 50.4 ATTN: Document Control Desk U,S, Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391

==Subject:==
Watts Bar Nuclear Plant (WBN) Unit 2 - Cycle 3 Steam Generator Tube Inspection Report In accordance with the requirements of WBN Technical Specification (TS) 5.9.9, "Steam Generator Tube Inspection Report", the Enclosure provides the 180 Day Steam Generator Inspection Report for Unit 2 Cycle 3. This report is required to be submitted within 180 days after the initial entry into MODE 4 following the completion of an inspection performed in accordance with TS 5.7.2.12, "Steam Generator (SG) Program." The report provides the complete results of the tube inspections.
There are no regulatory commitments contained in this letter. Please direct any questions concerning this matter to Tony Brown, WBN Licensing Manager, at (423) 365-7720.
Anthony L. Williams IV Site Vice President Watts Bar Nuclear Plant

U.S. Nuclear Regulatory Commission WBL-21-028 Page 2 May 10, 2021

==Enclosure:==

Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report cc: (w/o Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant

ENCLOSURE Tennessee Valley Authority Watts Bar Nuclear Plant Unit 2 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report

Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report Author:                            Signature / Date              For Pages 4/28/2021 Jesse S. Baron                                                       All SG Program Engineer Reviewers:                         Signature / Date              For Pages Jeremy W. Mayo                                                       All SG Program Manager 4/30/2021 Daniel P. Folsom                                                     All NDE Eddy Current Level III Managers Name:                    Signature / Date              For Pages Anne Robinson-Givens                                                 All Senior Programs Manager TVA EWR WO 122088253 Revision 0                                   April 2021 Page 1 of 15

Table of Contents 1.0 Introduction ...................................................................................................................................................... 3 2.0 180 Day Steam Generator Tube Inspection Report ......................................................................................... 4
: a. The Scope of Inspections Performed on each SG .......................................................................................... 4
: b. Degradation Mechanisms Found .................................................................................................................... 5
: c. Nondestructive Examination (NDE) Techniques Utilized for Each Degradation Mechanism ...................... 6
: d. Location, Orientation (if Linear), and Measured Sizes (if Available) of Service Induced Indications .......... 8
: e. Number of Tubes Plugged or Repaired During the Inspection Outage for Each Degradation Mechanism . 13
: f. The Number and Percentage of Tubes Plugged or Repaired to Date and the Effective Plugging Percentage in each SG .................................................................................................................................................... 14
: g. The Results of Condition Monitoring, Including the Results of Tube Pulls and In-Situ Testing ................ 14
: h. Repair Method Utilized and the Number of Tubes Repaired by Each Repair Method ................................ 15 List of Tables and Figures Figure 1-1: Tube Support Arrangement for Watts Bar Unit 2 Model D3 Steam Generators ................................. 3 Table 2-1: Watts Bar U2R3 Steam Generator Eddy Current Inspection Scope...................................................... 5 Table 2-2: Number of Indications Detected for Each Degradation Mechanism during U2R3 ............................... 6 Table 2-3: NDE Techniques for Each Degradation Mechanism ............................................................................ 7 Table 2-4: Watts Bar U2R3 Pre-Service Volumetric Indications - All SGs ........................................................... 8 Table 2-5: Watts Bar U2R3 Anti-Vibration Bar Wear Indications - All SGs ......................................................... 9 Table 2-6: Watts Bar U2R3 Tube Support Plate Wear Indications - All SGs....................................................... 10 Table 2-7: Watts Bar U2R3 Circumferential ODSCC at HTS Indications - All SGs ........................................... 11 Table 2-8: Watts Bar U2R3 Axial ODSCC at TSP Indications Excluded from GL 95 All SGs ................... 13 Table 2-9: Watts Bar U2R3 Axial ODSCC at HTS Indications - All SGs ........................................................... 13 Table 2-10: Watts Bar U2R3 Axial ODSCC at Tube Freespan Dings - All SGs.................................................. 13 Table 2-11: Watts Bar U2R3 Circumferential ODSCC at Tube Freespan Dings - All SGs ................................. 13 Table 2-12: Watts Bar U2R3 Axial PWSCC at HTS Indications - All SGs ......................................................... 13 Table 2-13: Number of Tubes Plugged for each Degradation Mechanism........................................................... 14 TVA EWR WO 122088253 Revision 0                                                                                                                              April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                                                                             Page 2 of 15

1.0     Introduction The third in-service inspections (ISI) of the Watts Bar Unit 2 (WBN2) steam generators (SGs) were performed during the fall 2020 refueling outage designated as U2R3. The U2R3 inspection was performed after 3.354 effective full power years (EFPY) of plant operation. The inspections included eddy current testing of the SG tubing as well as primary side visual inspections, secondary side visual inspections, and secondary side cleanings.
This report documents the Watts Bar U2R3 180-Day Steam Generator Tube Inspection Report as required by the WBN2 Technical Specifications. The steam generators at WBN2 are a Westinghouse Model D3 preheater-type design where the majority of the feedwater enters the tube bundle on the cold leg side and the tubing is made from mill annealed Alloy 600 (Alloy 600MA) material. Figure 1-1 below provides the arrangement and location designation of the tube support structures for the WBN2 SGs.
Figure 1-1: Tube Support Arrangement for Watts Bar Unit 2 Model D3 Steam Generators Notes: H/C/AV = Hot Leg Support/Cold Leg Support/Anti-Vibration Bar (AVB) Location HTS/CTS = Hot Leg Top of Tubesheet/Cold Leg Top of Tubesheet HTE/CTE = Hot Leg Tube End/Cold Leg Tube End TVA EWR WO 122088253 Revision 0                                                                April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                Page 3 of 15

2.0     180 Day Steam Generator Tube Inspection Report In accordance with WBN2 Technical Specification Section 5.7.2.12 Steam Generator Program and Technical Specification Section 5.9.9 Steam Generator Tube Inspection Report, this report documents the scope and results of the Watts Bar U2R3 SG inspections. There are eight specific reporting requirements associated with the Technical Specification. Each lettered reporting requirement listed below is followed with the associated information based on the inspections performed during U2R3.
: a. The Scope of Inspections Performed on each SG The inspection program addressed the known degradation observed in the Watts Bar Unit 2 SGs during the pre-service inspection, in-service inspections, and potential SG tube degradation mechanisms relevant to the design and material of the Watts Bar Unit 2 SG tubing. The inspections were performed with qualified non-destructive examination (NDE) techniques for each existing and potential mechanism. The defined base scope and expansion scope that was implemented in all four SGs included:
* 100% bobbin inspection of all open tubes in all four SGs full length and tube rows 1 through 4 to the top tube support plate from both the hot leg (HL) and cold leg (CL) sides.
* 100% +POINT probe inspection of tube Rows 1 through 4 from the top tube support plate on the HL side to the top tube support plate on the CL side.
        *  +POINT probe Special Interest inspections of tube locations with non-resolved bobbin and/or Array probe signals.
* 100% +POINT probe inspection of the hot leg top of tubesheet region from HTS+2/-2 inches.
* 50% Combination bobbin and Array probe inspection from C06 to CTS-2 inches in a checkerboard pattern. This inspection included all CL peripheral tubes two tubes deep, all tubes not inspected by the U2R2 cold leg combination bobbin and Array probe program and all possible loose part (PLP) indications detected as part of the combination bobbin and Array probe scope in the U2R2 inspections.
* 100% +POINT or Array probe inspection of all DNTs > 2 Volts
* 100% +POINT or Array probe inspection of all DNGs > 5 Volts in the HL straight lengths, U-bends and the top TSP on the CL side x Scope expanded to 100% +POINT or Array probe inspection of all DNGs > 2 Volts in SG2 x Scope expanded to 100% +POINT probe inspection of all DNGs > 5 Volts in SG4.
DNGs < 5 Volts were inspected with the 100% full length bobbin base scope program. The bobbin coil probe is qualified for axial ODSCC at DNGs.
* 25% +POINT or Array probe inspection of all DNGs > 2 Volts.
x Scope was expanded to 100% +POINT or Array probe inspection of all DNGs > 2 Volts in SG2.
x Scope was expanded to 100% +POINT probe inspection of all DNGs > 5 Volts in SG4. DNGs < 5 Volts were inspected with the 100% full length bobbin base scope program. The bobbin coil is qualified for axial ODSCC at DNGs.
* 100% +POINT probe inspection of any DNT or DNG signal located within 1.0 inch or less of a manufacturing burnish mark (MBM).
* 100% +POINT probe inspection of TSP mix residual signals that could cause a 1.0 Volt bobbin signal to be missed or misread as required by NRC Generic Letter 95-05.
        *  +POINT or Array probe inspection of tubes surrounding known locations of foreign objects from the pre-service inspections.
TVA EWR WO 122088253 Revision 0                                                                   April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                   Page 4 of 15

        * +POINT or Array probe inspection of all tubes within a two-tube pitch of the region surrounding any foreign object wear or PLP locations.
        * +POINT probe inspection of SG3 tube Row 47 Column 48 at H01 and all tubes within one tube of this location at the same elevation.
        * +POINT probe inspection of bobbin tube-to-tube proximity (PRO or PRX) signals >1.25 Volts with corresponding adjacent PRO or PRX signals.
* 100% visual inspection of all installed tube plugs from the primary side on both the HL and CL side.
* Visual inspection in all SGs of channel head primary side HL and CL inclusive of the entire divider plate to channel head weld and all visible clad surfaces. A follow-up inspection of the channel head clad anomaly in the hot leg of SG1 was also performed to confirm that the assessment of the condition remains applicable.
The Watts Bar U2R3 inspection included all tubes with prior indications of degradation. The table below summarizes the number and type of eddy current examinations performed during U2R3.
Table 2-1: Watts Bar U2R3 Steam Generator Eddy Current Inspection Scope Eddy Current Exam Type                SG 1      SG 2    SG 3  SG 4 Full Length Bobbin               4198      4190    4206  4199 CL R1-R4 Low Row Bobbin                451       450     454   454 HL R1-R4 Low Row Bobbin                451       450     454   454 U-Bend +Point R1-R4                 461       450     454   454 HL +Point Tubesheet               4649      4640    4660  4653 CL Straight Leg Array Probe 2701      2676    2686  2649 C06 to CTS-2 inch Ghent Probe Special Interest            4         5       3     1
                   +Point Straight Section Special Interest    905       930     649  353a Array Probe Special Interest           199       210      80    87 U-bend +Point Special Interest           23        10      9     7 Dent/Ding +Point Expansion              0        582      0     0 Note a: Includes SG4 scope expansion to all DNGs > 5 Volts In addition to the NDE and primary side inspections discussed, visual inspection was performed of the secondary side in all SGs in order to determine the deposit and foreign object removal effectiveness of the tubesheet cleaning process applied. This was followed by a secondary side foreign object search and retrieval (FOSAR) inspection performed at the top of the tubesheet in all four SGs. No visual inspections were performed of the SG upper internal components during U2R3 since the upper internals of all four SGs have been inspected between the U2R1 and U2R2 refueling outages.
: b. Degradation Mechanisms Found The following degradation mechanisms were detected during the U2R3 inspection:
          - Volumetric Indications due to Tube Fabrication and Installation (Pre-Service)
          - Mechanical Wear at Anti-Vibration Bars (AVBs)
          - Mechanical Wear at Tube Support Plates (TSPs)
TVA EWR WO 122088253 Revision 0                                                                  April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                  Page 5 of 15

           - Circumferential Outer Diameter Stress Corrosion Cracking (ODSCC) at the Hot Leg Tubesheet Expansion Transition
           -  Axial ODSCC at the Hot Leg TSP Intersections
           -  Axial ODSCC at Hot Leg Expansion Transitions/Sludge Pile - New Mechanism
           -  Axial ODSCC at Tube Freespan Dings - New Mechanism
           -  Circumferential ODSCC at Tube Freespan Dings - New Mechanism
           -  Axial Primary Water Stress Corrosion Cracking (PWSCC) at Hot Leg Tubesheet Expansion Transitions - New Mechanism Volumetric indications generated during tube manufacture and bundle assembly and initially detected during the pre-service inspections were also detected during U2R3. These indications are not considered an active or ongoing in-service degradation mechanism but are listed for completeness.
All of the in-service volumetric wear indications detected were located at tube intersections with either TSPs or AVBs. Axial ODSCC at Hot Leg Expansion Transitions/Sludge Pile, PWSCC at Hot Leg Expansion Transitions, and Axial and Circumferential ODSCC at Freespan Dings are new degradation mechanisms first observed during Watts Bar U2R3.
Table 2-2 below shows the number of indications reported for each degradation mechanism during the U2R3 inspections.
Table 2-2: Number of Indications Detected for Each Degradation Mechanism during U2R3 Degradation Mechanism            SG1       SG2       SG3       SG4      Total Volumetric Indications (Pre-Service)   13        2         7          14      36 Wear at Anti-Vibration Bars       10        13        3          28      54 Wear at Tube Support Plates        0         0         49         3       52 Circumferential ODSCC 6         1         44         18      69 at HL TTS Expansion Transition Axial ODSCC at Tube Support Plates    200       313       390        325     1228 Axial ODSCC at Tube Support Plates 0         1         10          1      12
                 > Upper Voltage Repair Limit Axial ODSCC at Tube Support Plates 0         0         3           0       3 Excluded from GL 95-05 Axial ODSCC 0         0         3           1       4 at HL TTS Expansion Transition Axial ODSCC 0         1         0           1       2 at Tube Freespan Ding Circumferential ODSCC 0         2         0           0       2 at Tube Freespan Ding Axial PWSCC 0         1         0           0       1 at HL TTS Expansion Transition
: c. Nondestructive Examination (NDE) Techniques Utilized for Each Degradation Mechanism Table 2-3 provides the NDE techniques that were used for the detection of each degradation mechanism considered as existing or potential for the U2R3 inspection. NDE techniques are also listed which were available for diagnostic testing, resolution, and confirmation of anomalous indications. All of the examination technique specification sheets (ETSSs) used during U2R3 are from the electric power research institute (EPRI) database. In some cases, a variable X is used in the listing of techniques in Table 2-3 which is in reference to a series of ETSSs.
TVA EWR WO 122088253 Revision 0                                                                    April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                    Page 6 of 15

Table 2-3: NDE Techniques for Each Degradation Mechanism Degradation Mechanism         ETSS Detection Technique Volumetric Indications due to             B: 27091.1 Tube Fabrication and Installation           B: 27091.2 B: 96041.1
                                                                 +Pt: 10908.4 Wear at                        A: 17908.1 AVBs                          A: 17908.2 A: 17908.4 A: 17908.5 B: 96042.1 A: 11956.1 Wear at A: 11956.2 Tube Support Plates A: 11956.3 A: 11956.4 B: 27091.1 Wear due to                     +Pt: 21998.1 Foreign Objects                   A: 1790X.1 A: 1790X.3 Tube-to-Tube B: 13091.2 Contact Wear B: 96005.3 OD Pitting of the Tube Material          +Pt: 21998.1 A: 24998.1
                                                               +Pt: 20511.1 Ax Axial and Circumferential            +Pt: I11524 Cir PWSCC at the TTS                   A: 20501.1 Ax A: 20500.1 Cir
                                                               +Pt: I28424 Ax Axial and Circumferential
                                                               +Pt: I28425 Ax ODSCC at the TTS
                                                               +Pt: 21410.1 Cir and Sludge Pile A: 20400.1 Ax/Cir Axial ODSCC                       B: I28411 at Tube                       +Pt: I28424 Support Plates                    A: 20402.1 Axial and Circumferential              +Pt: 96511.2 PWSCC in the                          or Low Row U-bends                     +Pt: 99997.1 ODSCC B: I28411 or B: 24013.1 B: 10013.1 ODSCC at                       +Pt: 22401.1 Tube Dents and Dings and Axial            +Pt: 21410.1 PWSCC at Dents                      A: 20400.1 A: 20403.1 PWSCC B: 96012.1 A: 20500.1 ODSCC
                                                               +Pt: I28424 Ax
                                                               +Pt: I28425 Ax
                                                               +Pt: 21410.1 Cir ODSCC and PWSCC at Tube A: 20400.1 Ax/Cir Bulges and Overexpansions PWSCC
                                                               +Pt: 20511.1 Ax
                                                               +Pt: I11524 Cir TVA EWR WO 122088253 Revision 0                                                     April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                     Page 7 of 15

Degradation Mechanism                   ETSS Detection Technique A: 20501.1 Ax A: 20500.1 Cir B: I28412 Axial ODSCC in the Freespan                            B: I28413 A: 20403.1 ODSCC at Dents and Dings                           +Pt: 22401.1 Coincident with an MBM                            +Pt: 21410.1 Diagnostic                             ETSS Technique Gh: 20406.1 Gh: 20407.1 Anomalous Gh: 20507.1 Indications Gh: 20508.1 Gh: 20509.1 Acronym Definitions for Table 2-3
             +Pt: +POINT Probe                                       Gh: Ghent Probe A: Array Probe                                          MBM: Manufacturing Burnish Mark AVB: Anti-Vibration Bar                                 OD: Outer Diameter Ax: Axial                                               ODSCC: Outer Diameter Stress Corrosion Cracking B: Bobbin Probe                                         PWSCC: Primary Water Stress Corrosion Cracking Cir: Circumferential                                    SCC: Stress Corrosion Cracking ETSS: Eddy current Technique Specification Sheet        TTS: Top of the Tubesheet
: d. Location, Orientation (if Linear), and Measured Sizes (if Available) of Service Induced Indications Table 2-4 through Table 2-12 provide a listing of all pre-service and service-induced indications reported during the U2R3 inspection. The tables also provide the estimated depths from the associated NDE technique and an indication of whether the tube has been plugged.
Implementation of GL 95-05 voltage-based alternate repair criteria for axial ODSCC degradation at TSP intersections excludes certain tubes and locations from application of the criteria.
Indications of axial ODSCC at TSPs in excluded tube locations are identified in Table 2-8. The remaining indications of axial ODSCC at TSPs which have been addressed by GL 95-05 requirements are provided in NRC Accession Number ML21042B342.
Table 2-4: Watts Bar U2R3 Pre-Service Volumetric Indications - All SGs SG         Row         Col         Location     Inch1       Indication         %TW             Plugged?
1            6         74            HTS        -0.19          VOL              30           Yes - U2R2 1            3         99            C14        0.08           VOL              17                No 1           10         38            C12         -2.5          VOL              23                No 1           10         55            C13       32.84           VOL              11                No 1           14         18            AV1          3.8          VOL              14                No 1           14         98            C14        1.69           VOL              18                No 1           28         83            C14        0.49           VOL              46       Yes - Pre-Service 1           30         73            C13       28.64           VOL               5                No 1           31         80            C14        1.84           VOL              24                No 1           32         65            C01          2.4          VOL               8                No 1           32         96            C14        0.52           VOL              27                No 1           34         77            C14        1.52           VOL               6                No 1           34         87            C14          0.2          VOL              41       Yes - Pre-Service 1           35         48            H08       25.26           VOL              18                No 1           38         72            AV4       29.55           VOL              39       Yes - Pre-Service 1           39         72            C14       -2.74           VOL              17                No 1           41         73            C14        0.58           VOL              30                No 2            5        103            H01        0.62           VOL              14                No 2            5        110            H01        0.44            SVI             46           Yes - U2R1 2           21         16            H03       33.19           VOL              11                No 2           25         28            C10       13.37           VOL              48       Yes - Pre-Service 2           27         31            C01       12.32           VOL              57       Yes - Pre-Service 3           19         37            C13        2.74           VOL              14                No 3           21         41            C01        3.88           VOL              20                No TVA EWR WO 122088253 Revision 0                                                                                             April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                                             Page 8 of 15

SG     Row      Col      Location    Inch1    Indication   %TW        Plugged?
3      22       43        C01        1.46        VOL        15          No 3      32       46        H01        4.89        VOL        32          No 3      38       42        H01        1.75        VOL        21          No 3      38       42        H01        1.12        VOL        11          No 3      38       58        H06       40.09        VOL        21          No 3      40       42        H01        1.97        VOL        38  Yes - Pre-Service 4       1       87        H01        2.96        VOL        21          No 4       3      106        C11       12.01        VOL        10          No 4       8       84        H04       21.84        VOL        20          No 4       9       44        H07       30.94        VOL        10          No 4      20       46        H07       22.43        VOL        10          No 4      21       31        H06        9.99        VOL        18          No 4      21       31        H06        2.03        VOL        14          No 4      21       31        H06       17.06        VOL        7           No 4      23       77        C09        7.31        VOL        13          No 4      27       46        H04       22.89        VOL        20          No 4      28       95        H04        25.6        VOL        16          No 4      29      100        C13        36.1        VOL        30          No 4      30       14        C10        9.02        VOL        20          No 4      30       35        C10         8.8        VOL        23          No 4      38       84        H04        3.39        VOL        15          No Table 2-5: Watts Bar U2R3 Anti-Vibration Bar Wear Indications - All SGs SG        Row        Col       Location    Inch1         Ind    %TW         Plugged?
1         24        108         AV4        0.13         PCT       14          No 1         35         14         AV2        0.16         PCT       10          No 1         36         91         AV3        0.12         PCT       21          No 1         40         79         AV2        0.19         PCT       13          No 1         42         90         AV3        0.05         PCT       17          No 1         43         54         AV3           0         PCT       12          No 1         47         64         AV2           0         PCT       12          No 1         48         73         AV2           0         PCT       10          No 1         48         79         AV2           0         PCT       10          No 1         48         81         AV3           0         PCT       11          No 2         20          6         AV1       -0.17         PCT       13          No 2         22          8         AV3        0.16         PCT       12          No 2         23          6         AV4          0.2        PCT       16          No 2         24          8         AV2        0.19         PCT       15          No 2         25          9         AV2        0.26         PCT       17          No 2         27         21         AV4        -0.05        PCT       10          No 2         30         23         AV4        0.13         PCT       11          No 2         32         15         AV2        0.15         PCT       10          No 2         35         85         AV3        0.19         PCT       18          No 2         35         93         AV2          0.1        PCT       11          No 2         36         79         AV3        -0.19        PCT       13          No 2         37         38         AV3        0.17         PCT       11          No 2         47         41         AV1        0.12         PCT       10          No 3         30        105         AV3         -0.1        PCT        9          No 3         42         93         AV4        0.04         PCT       10          No 3         43         73         AV2        0.16         PCT       16          No 4         28         79         AV3           0         PCT        8          No 4         29         79         AV3        0.14         PCT       9           No 4         29         90         AV1        0.34         PCT       12          No 4         33         14         AV3        0.09         PCT       10          No 4         34         13         AV2        0.17         PCT       10          No 4         35         68         AV2        0.16         PCT       11          No 4         38         21         AV3        0.14         PCT       15          No 4         41         24         AV2        0.16         PCT       10          No 4         41         24         AV3        0.23         PCT       14          No 4         41         74         AV3        0.17         PCT       14          No TVA EWR WO 122088253 Revision 0                                                                   April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                   Page 9 of 15

SG        Row        Col      Location     Inch1      Ind       %TW       Plugged?
4         41         88        AV3         -0.07    PCT          10         No 4         41         90        AV4         -0.02    PCT           7         No 4         41         94        AV3         0.24     PCT          12         No 4         42         29        AV2         0.25     PCT          19         No 4         42         29        AV3         0.16     PCT          12         No 4         42         36        AV3           0      PCT          21         No 4         42         40        AV2         0.21     PCT          13         No 4         42         40        AV3         0.32     PCT          18         No 4         42         64        AV1           0      PCT          11         No 4         42         65        AV3         0.14     PCT          14         No 4         42         78        AV3         -0.02    PCT          11         No 4         44         28        AV3         0.14     PCT          13         No 4         44         40        AV3           0      PCT          10         No 4         44         78        AV3         -0.02    PCT          10         No 4         46         75        AV3         0.07     PCT          10         No 4         49         59        AV1         0.12     PCT          15         No 4         49         60        AV3           0      PCT          14         No 4         49         60        AV4           0      PCT          14         No Table 2-6: Watts Bar U2R3 Tube Support Plate Wear Indications - All SGs SG    Row   Col    Location   Inch1       Ind    %TW      Plugged?
3     45    63      C06       -0.24      PCT      4          No 3     46    56      C05       0.02       PCT      5          No 3     46    56      C06       -0.28      PCT      9          No 3     46    57      C06          0       PCT      6          No 3     46    58      C06       -0.24      PCT      7          No 3     46    59      C05          0       PCT      6          No 3     46    60      C06       -0.24      PCT      4          No 3     46    61      C05       -0.02      PCT     13          No 3     46    61      C06       -0.03      PCT      4          No 3     46    65      C06       -0.21      PCT      8          No 3     47    56      C06       -0.28      PCT      8          No 3     47    57      C06       -0.16      PCT      6          No 3     47    58      C05       0.36       PCT      3          No 3     47    59      C02          0       PCT      7          No 3     47    59      C05         0.3      PCT     11          No 3     47    59      C06       -0.23      PCT      3          No 3     47    60      C03         0.3      PCT      4          No 3     47    60      C06       -0.16      PCT     26          No 3     47    62      C06       -0.21      PCT      7          No 3     47    63      C05          0       PCT     17          No 3     47    63      C06       -0.19      PCT      5          No 3     47    64      C05       -0.02      PCT      5          No 3     47    64      C06       -0.19      PCT     10          No 3     47    65      C05          0       PCT      9          No 3     48    51      C06       0.44       PCT      5          No 3     48    53      C05       -0.26      PCT      5          No 3     48    55      C05       -0.09      PCT      4          No 3     48    55      C06        -0.2      PCT      3          No 3     48    56      C05          0       PCT      5          No 3     48    56      C06          0       PCT      6          No 3     48    58      C03       0.14       PCT      5          No 3     48    58      C05       -0.02      PCT      6          No 3     48    60      C05       0.33       PCT      7          No 3     48    60      C06       -0.14      PCT     26          No TVA EWR WO 122088253 Revision 0                                                                 April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                 Page 10 of 15

SG     Row    Col    Location    Inch1        Ind       %TW       Plugged?
3      48    61       C02        0.02        PCT        10          No 3      48    61       C05        0.07        PCT        16          No 3      48    61       C06        -0.14       PCT         7          No 3      48    63       C05        -0.26       PCT         4          No 3      48    63       C06        -0.21       PCT         4          No 3      48    64       C05          0         PCT        20          No 3      48    64       C06        -0.21       PCT         8          No 3      48    65       C05          0         PCT        27          No 3      48    66       C05         -0.2       PCT         3          No 3      48    66       C06        0.02        PCT        22          No 3      49    59       C05        -0.23       PCT         7          No 3      49    59       C06        -0.14       PCT         8          No 3      49    60       C02          0         PCT         5          No 3      49    60       C06        -0.19       PCT        21          No 3      49    61       C06        -0.14       PCT        16          No 4      48    46       C06        -0.28       PCT        10          No 4      48    77       C05        0.15        PCT         7          No 4      49    74       C06        -0.26       PCT         5          No Table 2-7: Watts Bar U2R3 Circumferential ODSCC at HTS Indications - All SGs Indication Summary                         Resolution Sizing                          Depth Profiling Sizing            Plugged?
                                      +POINT     Maximum Segment          Quick               Maximum Segment          Depth Depth SG Row    Col     Ind   Locn   Inch1   300kHz      Depth,        Arc,     Screen                Depth,       Arc,      Profile Profiled?
Vpp        %TW         Deg.       PDA                  %TW          Deg.       PDA 1  3      70     SCI   HTS     -0.04    0.09        79         55.4        7.2      Yes         79           65       13.81      Yes 1  4      57     SCI   HTS     -0.05    0.09        44         32.3        2.3       No          -            -          -       Yes 1  4      65     SCI   HTS     -0.03    0.1         61         115.4      11.5      Yes         44          114        9.54      Yes 1  30     77     SCI   HTS     -0.16    0.27        90         163.1      24.1      Yes         86          172       35.42      Yes 1  41     39     SCI   HTS     -0.17    0.15        15         56.9        1.9       No          -            -          -       Yes 1  44     30     SCI   HTS     -0.02    0.19        90          67.7      10.0      Yes         96           81       19.91      Yes 2  45     65     SCI   HTS     -0.06    0.11        50         84.6        6.9       No          -            -          -       Yes 3  5      96     SCI   HTS     -0.12    0.18       NQI1         66.2       2.2       No          -            -          -       Yes 3  6      21     SCI   HTS     -0.02    0.28         9         116.9       3.8       No          -            -          -       Yes 3  9      70     SCI   HTS     -0.03    0.22        63         61.5        6.3       No          -            -          -       Yes 3  9      98     SCI   HTS     -0.11    0.19        45         86.2        6.4       No          -            -          -       Yes 1
3  10     78     SCI   HTS     -0.15    0.2        NQI          81.5       2.7       No          -            -          -       Yes 3  12     67     MCI   HTS     -0.08    0.17        53          83.1       7.2       No          -            -          -       Yes 3  12    100     SCI   HTS     -0.07    0.33        30         166.2       8.2       No          -            -          -       Yes 3  12    105     SCI   HTS     -0.11    0.16        36         90.8        5.4       No          -            -          -       Yes 3  13     88     SCI   HTS     -0.09    0.16        26         52.3        2.2       No          -            -          -       Yes 3  14     55     SCI   HTS     -0.15    0.25       NQI1        109.2       3.6       No          -            -          -       Yes 3  14     57     SCI   HTS     -0.17    0.13        53         49.2        4.3       No          -            -          -       Yes 3  14     91     MCI   HTS     -0.05    0.21        31         123.1       6.3       No          -            -          -       Yes 3  14     98     SCI   HTS     -0.08    0.18        67         66.2        7.3       No          -            -          -       Yes 3  14     99     SCI   HTS      -0.1    0.29        73          87.7      10.5      Yes         45          101        8.91      Yes 3  14    101     SCI   HTS     -0.05    0.29        48         116.9       9.2       No          -            -          -       Yes 3  15     82     SCI   HTS     -0.04    0.17        31          116        5.9       No          -            -          -       Yes 3  16     71     SCI   HTS     -0.15    0.14        12         43.1        1.4       No          -            -          -       Yes 3  17     44     SCI   HTS     -0.04    0.41         0         198.5       6.5      Yes         20          194        11.3      Yes 3  19     57     SCI   HTS     -0.09    0.19        35          160        9.2       No          -            -          -       Yes 3  21     56     SCI   HTS     -0.04    0.29        45         113.8       8.4       No          -            -          -       Yes 3  22     62     SCI   HTS     -0.05    0.31        35         184.6      10.6       No          -            -          -       Yes TVA EWR WO 122088253 Revision 0                                                                              April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                            Page 11 of 15

Indication Summary                            Resolution Sizing                             Depth Profiling Sizing                Plugged?
                                               +POINT     Maximum Segment          Quick                  Maximum Segment            Depth Depth SG     Row     Col      Ind Locn     Inch1    300kHz       Depth,        Arc,     Screen                   Depth,         Arc,      Profile Profiled?
Vpp        %TW          Deg.       PDA                     %TW           Deg.        PDA 3      22      66      SCI HTS       -0.1      0.62        39          186.2      11.9        Yes           52           212       26.61        Yes 3      22      84      SCI HTS      -0.11      0.11        22           72.3       2.6        No              -            -          -         Yes 3      23      56     MCI  HTS      -0.06      0.27        27           197        8.7        Yes           75           319       28.29        Yes 3      23      85      SCI HTS      -0.04      0.14        68          166.2      18.5        Yes           86           177       29.66        Yes 3      25      60      SCI HTS      -0.23      0.32        36          135.4       8.0        No              -            -          -         Yes 3      26      45      SCI HTS       -0.1      0.28        18           95.4       3.1        No              -            -          -         Yes 3      26      71      SCI HTS      -0.09      0.2         21           90.8       3.1        No              -            -          -         Yes 3      29      21      SCI HTS       -0.1      0.19       NQI1         118.5        3.9       No              -            -          -         Yes 3      32      57      SCI HTS      -0.05      0.15        70           83.1       9.5        No              -            -          -         Yes 3      38      59     MCI  HTS      -0.04      0.15        78          144.6      18.5        Yes           48           161       21.79        Yes 3      39      28      SCI HTS      -0.05      0.11        14            80         2.6       No              -            -          -         Yes 3      40      64     MCI  HTS      -0.05      0.27        33          150.8       8.2        No              -            -          -         Yes 3      41      71      SCI HTS       -0.1      0.15        39            60        3.8        No              -            -          -         Yes 3      43      25      SCI HTS      -0.08      0.26        52           67.7       5.8        No              -            -          -         Yes 26A      SCI HTS      -0.05      0.16        51           73.8       6.2        Yes          51.0           89        8.41        Yes 3      44 26B      SCI HTS      -0.05      0.26        52           100        8.5        Yes           76           110        16.9        Yes 3      45      28      SCI HTS      -0.08      0.22        55           76.9       6.9        No              -            -          -         Yes 3      45      38      SCI HTS      -0.03      0.13        34          143.1       8.0        No              -            -          -         Yes 3      46      74     MCI  HTS      -0.14      0.18        50           84.6       6.9        No              -            -          -         Yes 3      46      83      SCI HTS      -0.05      0.17        16           55.4       1.8        No              -            -          -         Yes 3      47      73      SCI HTS      -0.07      0.18        28           100         4.6       No              -            -          -         Yes 3      49      31      SCI HTS      -0.04      0.26       NQI1         146.2        4.8       No              -            -          -         Yes 3      49      79      SCI HTS      -0.04      0.17       NQI1          61.5        2.0       No              -            -          -         Yes 38A     MCI  HTS      -0.05      0.21        44          116.9       8.4        Yes          40.0          114        8.23        Yes 3      49 38B     MCI  HTS      -0.06      0.18        81            60        8.0        Yes           84            63       11.32        Yes 4       5      76      SCI HTS       0.07      0.17        21          163.1       5.6        No              -            -          -         Yes 4       6      82      SCI HTS       0.04      0.24        21          166.2       5.7        No              -            -          -         Yes 4       6      84      SCI HTS        0        0.2         32          232.3      12.2        Yes           60           251       20.41        Yes 4      10      82      SCI HTS      -0.15      0.19        35           58.5       3.4        No              -            -          -         Yes 4      11      56      SCI HTS       -0.1      0.17        27           95.4       4.7        No              -            -          -         Yes 4      15     104      SCI HTS      -0.06      0.24        26          144.6       6.2        No              -            -          -         Yes 4      15     105      SCI HTS      -0.06      0.2         11          107.7       3.5        No              -            -          -         Yes 4      16      55      SCI HTS      -0.13      0.25        21          110.8       3.8        No              -            -          -         Yes 4      16      79      SCI HTS      -0.03      0.26        42           95.4       6.6        No              -            -          -         Yes 4      17      67      SCI HTS      -0.71      0.21        39          133.8       8.6        No              -            -          -         Yes 4      18      66      SCI HTS      -0.21      0.27        50          190.8      15.6        Yes           62           192       13.51        Yes 4      19      68      SCI HTS       -0.1      0.24        58           67.7       6.4        No              -            -          -         Yes 4      19      77      SCI HTS       -0.1      0.24        24           56.9       2.2        No              -            -          -         Yes 4      20      68      SCI HTS      -0.01      0.3         26          196.9       8.4        Yes           64           190       20.15        Yes 4      21      57      SCI HTS      -0.01      0.36        43           180        12.7       Yes           65           204       27.38        Yes 4      21      67      SCI HTS      -0.03      0.21        28          136.9       6.3        No              -            -          -         Yes 4      21      74      SCI HTS      -0.19      0.18        39           67.7       4.3        No              -            -          -         Yes 4      22      57      SCI HTS -0.34           0.41        28          116.9       5.4        Yes           39           147       11.71        Yes Note 1: An NQI is a non-quantifiable indication where the eddy current data analysts believe the indication is flaw-like although the associated depth is not measurable.
TVA EWR WO 122088253 Revision 0                                                                                       April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                                     Page 12 of 15

Table 2-8: Watts Bar U2R3 Axial ODSCC at TSP Indications Excluded from GL 95 All SGs Axial SG         Row            Col       Location     Inch1        Ind        %TW                       Plugged?
Ext. (in.)
3          21             37          H01        0.13        SAI          58.2         0.26          Yes 3          27             47          H01        0.11       MAI           48.6         0.24          Yes 3          47             87          H04        -0.01       SAI          51.7         0.39          Yes Note: The remaining indications of axial ODSCC at TSPs which have been addressed by GL 95-05 requirements are provided in ML21042B342.
Table 2-9: Watts Bar U2R3 Axial ODSCC at HTS Indications - All SGs Axial SG         Row            Col       Location     Inch1        Ind        %TW                      Plugged?
Ext. (in.)
3           23            56          HTS          0.5       SAI         47.6          0.45         Yes 3           23            66          HTS          0.2       SAI         52.8          0.23         Yes 3           24            65          HTS          0.6       SAI         48.1          0.20         Yes 4           22            69          HTS        -0.11       SAI         60.0          0.10         Yes Table 2-10: Watts Bar U2R3 Axial ODSCC at Tube Freespan Dings - All SGs Flaw       Ding         Ding Axial       Axial      Bobbin SG        Row        Col        Location      Inch1       Ind     %TW                                           Plugged?
Ext.       Ext.         Vpp (in.)      (in.)      (Volts) 2          9         86           H02          1.27     SAI        65        0.29       0.96          13          Yes 4         49         84           AV2          1.32     SAI        70        0.19       0.79          16          Yes Table 2-11: Watts Bar U2R3 Circumferential ODSCC at Tube Freespan Dings - All SGs Flaw       Ding         Ding Circ       Circ       Bobbin SG        Row        Col        Location      Inch1       Ind     %TW                                           Plugged?
Ext.       Ext.         Vpp (Deg.)     (Deg.)      (Volts) 2         17        109           C14         -2.02     SCI        66         57         168          26          Yes 2          7         58           H02         -1.95     SCI        67         25         101          27          Yes Table 2-12: Watts Bar U2R3 Axial PWSCC at HTS Indications - All SGs Axial SG         Row            Col       Location     Inch1        Ind        %TW                       Plugged?
Ext. (in.)
2          17            100          HTS         0.04       SAI           68          0.11          Yes
: e. Number of Tubes Plugged or Repaired During the Inspection Outage for Each Degradation Mechanism There were 189 tubes plugged during the Watts Bar U2R3 SG in-service inspection. Table 2-13 below provides the numbers and percentages of tubes plugged following U2R3.
TVA EWR WO 122088253 Revision 0                                                                                April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                               Page 13 of 15

Table 2-13: Number of Tubes Plugged for each Degradation Mechanism SG1       SG2         SG3          SG4     Total Plugged Tubes prior to U2R3            25        34          14           21       94 Plugging Reason                          Tubes Plugged during U2R3 Volumetric Indication from Pre-Service       0         0           0           0         0 Wear at AVBs                     0         0           0           0         0 Wear at TSPs                    0         0           0           0         0 Circumferential ODSCC at HTS             6          1          44           18       69*
Axial ODSCC at HL TSPs                3*         17         75          17*      112*
Axial ODSCC at HTS                   0         0           3           1         4 Axial ODSCC at Tube Freespan Dings           0         1           0           1        2*
Circumferential ODSCC at Tube 0         2           0           0         2 Freespan Dings Axial PWSCC at HTS                   0         1           0           0         1 Preventive                     1         0           0           0         1 Total Plugged Following U2R3            34*       56         136          57*      283*
Effective Tube Percentage 0.73%     1.20%       2.91%       1.22%     1.51%
Plugged Following U2R3
          *Two tubes had pluggable indications by two different degradation mechanisms. The Total Plugged Following U2R3 line item total has been adjusted to reflect this distinction.
One of the tubes plugged in SG1 was preventively plugged due to tube material pilgering chatter along the inner diameter observable by the bobbin probe inspection. The remaining tubes were plugged due to indications of cracking degradation in accordance with the requirements of the Watts Bar Unit 2 Technical Specification. There were no tubes repaired during the Watts Bar U2R3 refueling outage inspections.
: f. The Number and Percentage of Tubes Plugged or Repaired to Date and the Effective Plugging Percentage in each SG Table 2-13 provides the number and percentage of tubes plugged to date along with the effective tube plugging percentage in each SG and overall. No tubes have been repaired at Watts Bar Unit 2 to date.
: g. The Results of Condition Monitoring, Including the Results of Tube Pulls and In-Situ Testing Condition Monitoring, Tube Pulls and In-Situ Testing A condition monitoring (CM) assessment was performed as required by the Watts Bar Unit 2 steam generator program. Based on the Watts Bar U2R3 SG inspection data, all tubes with observed degradation satisfied the condition monitoring criteria for structural and leakage integrity with the exception of axial ODSCC at tube support intersections evaluated in accordance with NRC GL 95-05 voltage-based alternate repair criteria. Evaluation of axial ODSCC at tube support intersections against GL 95-05 is provided separately in ML21042B342.
In situ pressure testing was not required to demonstrate structural and leakage integrity. There was no detectable primary-to-secondary leakage during the operating interval prior to the Watts Bar U2R3 SG inspections. No indications of degradation addressed by this report were found to be in excess of the CM limits. The SG performance criteria for operating leakage and structural integrity TVA EWR WO 122088253 Revision 0                                                                         April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                         Page 14 of 15

were satisfied for the preceding Watts Bar Unit 2 SG inspection interval. No tube pulls were planned or performed during U2R3.
Primary and Secondary Side Visual Inspection Results Visual inspections were performed on both the primary and secondary sides during U2R3 in all four SGs. Primary side inspections performed in accordance with Westinghouse Nuclear Safety Advisory Letter NSAL-12-1 included the hot leg and cold leg divider plate, inclusive of the divider plate-to-channel head weld, and all visible clad surfaces of the SG channel head. The NSAL-12-1 examinations performed during U2R1 showed visually apparent evidence of minor indications of degradation of the cladding in SG1 located on the hot leg side just above the primary manway opening. This indication was re-inspected during U2R3. The conclusion of the engineering evaluation performed after U2R1 was that acceptable margin exists for maintenance of structural integrity of the SG channel head base metal for at least six cycles of operation. This conclusion was considered to remain applicable following the U2R3 inspection. No new indications were reported from the visual examinations of the channel head cladding.
All previously installed tube plugs were visually inspected from the primary side in all four SGs.
The inspection results were satisfactory and showed no indication of tube plug leakage or failure.
Prior to the secondary side FOSAR inspections, sludge, scale, foreign objects, and other deposit accumulations at the top of the tubesheet were removed as part of the top of tubesheet sludge lancing process. A total of 55.2 pounds of deposit was removed as a result of sludge lancing from all four SGs in total.
The secondary side FOSAR inspections performed in all four SGs included visual examination of tube bundle periphery tubes from the hot leg and cold leg annulus and center no-tube lane inclusive of the blowdown pipe connections with the tubesheet. A total of nineteen foreign objects were identified, six of which were removed from the top of the tubesheet region. The foreign objects retrieved consist of wire bristles, sludge rocks, and hardened scale. Of the thirteen objects remaining in the SG secondary side, only two of them are believed to be metallic. These include a 0.5 inch long 0.015 inch diameter metal bristle and a small metal object measuring 0.75 x 0.3 x 0.2 inch. Foreign objects remaining in the SGs were characterized and an analysis performed to demonstrate acceptability of continued operation without exceeding the tube integrity performance criteria.
Visual inspections of the steam drum upper internal components were not performed during U2R3.
: h. Repair Method Utilized and the Number of Tubes Repaired by Each Repair Method No tubes have been repaired at Watts Bar Unit 2 to date.
TVA EWR WO 122088253 Revision 0                                                                  April 2021 Watts Bar U2R3 180 Day Steam Generator Tube Inspection Report                                  Page 15 of 15}}