CNL-22-109, Steam Generator Tube Inspection Report to Reflect TSTF-577 Reporting Requirements

From kanterella
Jump to navigation Jump to search
Steam Generator Tube Inspection Report to Reflect TSTF-577 Reporting Requirements
ML22356A149
Person / Time
Site: Watts Bar Tennessee Valley Authority icon.png
Issue date: 12/22/2022
From: Rymer S
Tennessee Valley Authority
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
CNL-22-109
Download: ML22356A149 (1)
v • d • e


Text

1101 Market Street, Chattanooga, Tennessee 37402 CNL-22-109 December 22, 2022 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating Licenses No. NPF-90 NRC Docket No. 50-390

Subject:

Watts Bar Nuclear Plant, Unit 1, Steam Generator Tube Inspection Report to Reflect TSTF-577 Reporting Requirements

References:

1. TVA letter to NRC, CNL-22-001, Application to Revise Technical Specifications to Adopt TSTF-577, Revised Frequencies for Steam Generator Tube Inspections (SQN-TS-21-03 and WBN-TS-21-08), dated April 4, 2022 (ML22095A023)
2. NRC letter to TVA, Sequoyah Nuclear Plant, Units 1 and 2; and Watts Bar Nuclear Plant, Units 1 and 2 - Issuance of Amendment Nos. 359, 353, 155, and 63 Regarding Adoption of Technical Specification Task Force Traveler TSTF-577, Revised Frequencies for Steam Generator Tube Inspections (EPID L-2022-LLA-0051), dated October 24, 2022 (ML22276A161)
3. TVA letter to NRC, Watts Bar Nuclear Plant (WBN) Unit 1 - Cycle 14 Steam Generator Tube lnspection Report, dated July 28, 2017 (ML17209A554)

In Reference 1, Tennessee Valley Authority (TVA) submitted a request for an amendment to Renewed Facility Operating License Nos. DPR-77 and DPR-79 for the Sequoyah Nuclear Plant (SQN), Units 1 and 2 and Facility Operating License Nos. NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN), Units 1 and 2, respectively, to adopt Technical Specifications Task Force (TSTF)-577, Revised Frequencies for Steam Generator Tube Inspections. Reference 1 was approved by the Nuclear Regulatory Commission (NRC) in Reference 2. As noted in Reference 1, TVA will submit a SG Tube Inspection Report for WBN Unit 1 meeting the revised TS 5.9.9 requirements within 30 days after implementation of the license amendment. Reference 2 was implemented on November 30, 2022; therefore, the required WBN Unit 1 steam generator (SG) tube inspection report to reflect the TSTF-577 reporting requirements is required to be submitted to NRC by December 30, 2022.

U.S. Nuclear Regulatory Commission CNL-22-109 Page 2 December 22, 2022 Accordingly, the enclosure provides the revised 180-day report with the revised WBN Unit 1 TS 5.9.9 reporting requirements in accordance with References 1 and 2. Each WBN Unit 1 TS 5.9.9 reporting requirement is listed below along with the associated information based on the inspection performed during the WBN Unit 1 Cycle 14 spring 2017 refueling outage (U1R14), which was the last inspection of the WBN Unit 1 replacement steam generators (RSG) (Reference 3).

The SG tube inspection reports for SQN Units 1 and 2 will be submitted under separate correspondence. As noted in Reference 1, The WBN Unit 2 SGs were replaced during the U2R4 outage in spring 2022. Therefore, the initial inspection period described in the SG Program, paragraph d.2 will not commence until the WBN U2R5 refueling outage, scheduled for fall 2023, where there is a required 100% inspection of the WBN Unit 2 replacement SGs. Therefore, there is no revised 180-day inspection report required for the WBN Unit 2 5SG.

There are no new regulatory commitments associated with this submittal. Please address any questions regarding this request to slrymer@tva.gov.

Respectfully, Digitally signed by Rymer, Stuart Loveridge Date: 2022.12.22 10:41:00 -05'00' Stuart L. Rymer Director (Acting), Nuclear Regulatory Affairs

Enclosure:

Watts Bar Nuclear Plant, Unit 1 Steam Generator Tube Inspection Report cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant

Enclosure Watts Bar Nuclear Plant, Unit 1 Steam Generator Tube Inspection Report Introduction In Reference 1, Tennessee Valley Authority (TVA) submitted a request for an amendment to Facility Operating License No. NPF-90 for the Watts Bar Nuclear Plant (WBN), Unit 1 to adopt Technical Specifications Task Force (TSTF)-577, "Revised Frequencies for Steam Generator Tube Inspections." Reference 1 was approved by the Nuclear Regulatory Commission (NRC) in Reference 2. As noted in Reference 1, TVA will submit a SG Tube Inspection Report for WBN Unit 1 meeting the revised technical specification (TS) 5.9.9 requirements within 30 days after implementation of the license amendment. Reference 2 was implemented on November 30, 2022.

WBN Unit 1 Technical Specification (TS) 5.9.9, Steam Generator Tube Inspection Report, states, A report shall be submitted within 180 days after the initial entry into MODE 4 following completion of an inspection performed in accordance with the Specification 5.7.2.12, Steam Generator (SG) Program. This enclosure provides the revised 180-day report with the revised WBN Unit 1 TS 5.9.9 reporting requirements in accordance with References 1 and 2. Each WBN Unit 1 TS 5.9.9 reporting requirement is listed below along with the associated information based on the inspection performed during the WBN Unit 1 Cycle 14 spring 2017 refueling outage (U1R14), which was the last inspection of the WBN Unit 1 replacement steam generators (RSG) (Reference 3). This report follows the template provided in Appendix G to the Electric Power Research Institute (EPRI) Steam Generator Management Program: Steam Generator Integrity Assessment Guidelines, Revision 5 (Reference 4), which provides additional information beyond the WBN Unit 1 TS 5.9.9 reporting requirements.

TVA submitted the condition monitoring and operational assessment (CMOA) for WBN Unit 1 Cycle 14 to the NRC in Reference 5. TVA discovered a one percent (%) error in the effective full power years (EFPY) utilized for the generation of the CMOA. The CMOA was revised, and this report contains the corrected values provided in Sections 6 and 8 to this enclosure. The 3P performance criteria burst pressure is 3798 pounds per square inch (psi).

1. Design and operating parameters The WBN Unit 1 RSGs were installed in 2006. The RSGs are Westinghouse Model 68AXP with thermally treated alloy 690 tubing (690TT). U1R14 was the third inspection since installation of the RSGs and the RSGs had operated for three fuel cycles since the previous inspection (U1R11). The RSGs have operated for seven fuel cycles since replacement.

Table 1 provides the WBN Unit 1 SG design and operating parameter information.

CNL-22-109 E1 of 32

Enclosure Table 1 Steam Generator Design and Operating Parameters SG Model / Tube Material / Westinghouse Model 68AXP / Alloy 690TT/ 4 Number of SGs per Unit Number of tubes per SG / 5128 / 0.75 in. / 0.043 in.

Nominal Tube Diameter / tube thickness Support Plate Style / Material Advance Tube Support Grid / 409 stainless Steel Last Inspection Date fall 2012 (U1R11)

EFPM Since Last Inspection 48.36 (4.03 EFPY) (as of U1R14)

Total Cumulative SG EFPY 9.29 EFPY (as of U1R14)

Mode 4 Initial Entry 4/25/2017 Observed Primary-to-Secondary Below detection Leak Rate Nominal Thot at Full Power 617ºF Operation Loose Parts Strainer The Model 68AXP has a feedwater flow distribution box with small diameter holes acting as strainers to prevent the introduction of significant foreign objects into the SGs Degradation Mechanism There are no sets of tubing designated as degradation Sub-Population mechanism sub-populations in the U1R14 CMOA.

SG program guideline deviations None since last Inspection SG Schematic See Figure 1 CNL-22-109 E2 of 32

Enclosure Figure 1 WBN Unit 1 RSG Schematic CNL-22-109 E3 of 32

Enclosure

2. The scope of the inspections performed on each SG (TS 5.9.9.a) and if applicable, a discussion of the reason for scope expansion The U1R14 outage included a combination array/bobbin probe inspections of 100% of the full length in the in-service tubes except for low tubes. Low rows had their straight legs examined with the combination array/bobbin probe from both the hot leg tube end (HTE) and the cold leg tube end (CTE). The remainder of the low row tubes (U-bend region) were inspected with a singular bobbin probe due to dimensional clearance restrictions in the U-bend region. As a result, the inspection included the tubes with prior indications of degradation and the tubes not inspected during the previous SG in-service inspection.

Table 2 summarizes the number and type of eddy current examinations performed during U1R14. No scope expansion occurred in U1R14.

Table 2 U1R14 Steam Generator Eddy Current Inspection Scope Eddy Current Exam Type SG 1 SG 2 SG 3 SG 4 Total 0.610 HL Array-Bobbin VS3-HTE 4998 4996 4994 4987 19975 0.610 CL Array-Bobbin VS3-CTE 4998 4996 4994 4987 19975 0.610 HL Array-Bobbin H11-HTE (R1-2) 127 127 127 127 508 0.610 CL Array-Bobbin C12-CTE (R1-2) 127 127 127 127 508 0.610/0.590 HL/CL Bobbin (U-bend 127 127 127 127 508 Region R1-2)

In addition to the eddy current inspections, visual inspections were also performed on both the primary and secondary sides. Primary side visual inspections included the previously installed tube plugs, the channel head bowl cladding, and the divider plate. Secondary side visual inspections were performed at the top of the tubesheet for the detection of foreign objects, assessment of hard deposit buildup in the tube bundle interior kidney region and for determining the effectiveness of the tubesheet cleaning performed in the four SGs.

3. The nondestructive examination techniques utilized for tubes with increased degradation susceptibility (TS 5.9.9.b)

No tubes were designated as having increased degradation susceptibility during the U1R14 inspection.

4. The nondestructive examination technique utilized for each degradation mechanism found (TS 5.9.9.c.1)

Table 3 provides the nondestructive examination (NDE) techniques that were used for the detection of each degradation mechanism that was considered as existing or potential for the U1R14 inspection.

CNL-22-109 E4 of 32

Enclosure Table 3 NDE Techniques for Each Existing or Potential Degradation Mechanism EPRI Examination Degradation Mechanism Detection Technique Technique Specification Sheets (ETSS)

Bobbin 96004.1, Revision 13 Array 11956.1, Revision 2 U-Bend Support Structure Array 11956.2, Revision 2 Wear Array 11956.3, Revision 2 Array 11956.4, Revision 2 Bobbin 96004.1, Revision 13 Array 11956.1, Revision 2 Horizontal Tube Support Array 11956.2, Revision 2 Grid Wear Array 11956.3, Revision 2 Array 11956.4, Revision 2 Bobbin 27091.2, Revision 2 Array 11956.1, Revision 2 Foreign Object Wear Array 11956.2, Revision 2 Array 11956.3, Revision 2 Array 11956.4, Revision 2 Tube-to-Tube Wear Bobbin 96010.1, Revision 7

5. The location, orientation (if linear), measured size (if available), and voltage response for each indication. For tube wear at support structures less than 20 percent through-wall, only the total number of indications needs to be reported (TS 5.9.9.c.2)

Wear at support structures was the only degradation mechanism detected during the U1R14 inspection. The wear indications detected were located at either U-bend or horizontal tube support structures. Table 4 provides the number of indications reported during the U1R14 inspection.

Table 4 Number of Indications Detected for Each Degradation Mechanism Degradation Mechanism SG 1 SG 2 SG 3 SG 4 Total U-bend Support Structure Wear 13 11 23 12 59 Horizontal Tube Support Grid Wear 74 139 83 123 419 Tables 5 and 6 provide a listing of the service-induced indications reported during the U1R14 inspection including the estimated depths from the bobbin coil. Indications of tube wear at support structures are provided regardless of percent through-wall depth.

CNL-22-109 E5 of 32

Enclosure Table 5 U1R14 U-bend Support Structure Wear Indications - All SGs

% through SG Row Col Loc Inch Volts Indic wall (TW) Characterization Resolution U-bend Support Remain In-1 53 74 VS4 -1.15 0.21 PCT 15 Structure Wear Service U-bend Support Remain In-1 58 47 VS3 -0.96 0.27 PCT 16 Structure Wear Service U-bend Support Remain In-1 58 47 VS3 1.29 0.25 PCT 16 Structure Wear Service U-bend Support Remain In-1 66 65 VS4 0.86 0.42 PCT 19 Structure Wear Service U-bend Support Remain In-1 77 56 VS3 -0.91 0.38 PCT 18 Structure Wear Service U-bend Support Remain In-1 77 82 VS3 -1.12 0.3 PCT 17 Structure Wear Service U-bend Support Remain In-1 82 83 VS4 -1.01 0.35 PCT 18 Structure Wear Service U-bend Support Remain In-1 95 58 VS2 -0.61 0.24 PCT 15 Structure Wear Service U-bend Support Remain In-1 105 68 DS2 -0.23 0.24 PCT 15 Structure Wear Service U-bend Support Remain In-1 105 68 DS2 0.62 0.49 PCT 21 Structure Wear Service U-bend Support Remain In-1 105 68 VS2 -0.72 0.34 PCT 18 Structure Wear Service U-bend Support Remain In-1 105 68 VS2 -0.03 0.4 PCT 19 Structure Wear Service U-bend Support Remain In-1 105 68 VS4 -1.03 0.3 PCT 17 Structure Wear Service U-bend Support Remain In-2 65 98 VS2 1.24 0.33 PCT 17 Structure Wear Service U-bend Support Remain In-2 67 96 VS2 1.05 0.17 PCT 14 Structure Wear Service U-bend Support Remain In-2 75 54 VS4 0.86 0.58 PCT 22 Structure Wear Service U-bend Support Remain In-2 90 67 VS2 -0.85 0.15 PCT 12 Structure Wear Service U-bend Support Remain In-2 90 67 VS4 -0.76 0.39 PCT 18 Structure Wear Service U-bend Support Remain In-2 91 58 VS2 0.8 0.47 PCT 20 Structure Wear Service U-bend Support Remain In-2 96 63 VS3 -0.64 0.62 PCT 22 Structure Wear Service U-bend Support Remain In-2 99 58 VS4 0.8 0.39 PCT 18 Structure Wear Service U-bend Support Remain In-2 100 63 VS2 -0.75 0.78 PCT 24 Structure Wear Service U-bend Support Remain In-2 100 63 VS2 0.55 0.34 PCT 18 Structure Wear Service U-bend Support Remain In-2 101 52 VS1 -0.93 0.15 PCT 13 Structure Wear Service U-bend Support Remain In-3 24 69 DS4 -0.03 0.75 PCT 23 Structure Wear Service CNL-22-109 E6 of 32

Enclosure Table 5 U1R14 U-bend Support Structure Wear Indications - All SGs

% through SG Row Col Loc Inch Volts Indic wall (TW) Characterization Resolution U-bend Support Remain In-3 43 78 VS3 -1.2 0.24 PCT 16 Structure Wear Service U-bend Support Remain In-3 50 85 VS3 -0.38 0.45 PCT 20 Structure Wear Service U-bend Support Remain In-3 53 82 VS3 -0.12 0.43 PCT 19 Structure Wear Service U-bend Support Remain In-3 63 82 VS3 1.35 0.29 PCT 17 Structure Wear Service U-bend Support Remain In-3 64 81 VS3 1.82 0.29 PCT 17 Structure Wear Service U-bend Support Remain In-3 81 56 VS4 0.89 1.11 PCT 27 Structure Wear Service U-bend Support Remain In-3 82 43 VS2 -0.95 0.38 PCT 18 Structure Wear Service U-bend Support Remain In-3 96 67 VS2 -0.78 0.28 PCT 16 Structure Wear Service U-bend Support Remain In-3 97 56 VS3 0.74 0.47 PCT 20 Structure Wear Service U-bend Support Remain In-3 97 56 VS3 1.21 0.4 PCT 19 Structure Wear Service U-bend Support Remain In-3 97 64 DS3 -0.83 0.42 PCT 19 Structure Wear Service U-bend Support Remain In-3 98 71 VS4 0.73 0.48 PCT 20 Structure Wear Service U-bend Support Remain In-3 99 50 DS3 0.82 0.35 PCT 18 Structure Wear Service U-bend Support Remain In-3 99 58 VS4 0.03 0.32 PCT 17 Structure Wear Service U-bend Support Remain In-3 99 58 VS4 0.96 0.52 PCT 21 Structure Wear Service U-bend Support Remain In-3 100 55 VS2 -0.75 0.45 PCT 20 Structure Wear Service U-bend Support Remain In-3 100 63 DS3 0.8 0.3 PCT 17 Structure Wear Service U-bend Support Remain In-3 100 67 DS3 0.75 0.35 PCT 18 Structure Wear Service U-bend Support Remain In-3 101 58 DS2 -0.8 0.49 PCT 21 Structure Wear Service U-bend Support Remain In-3 101 58 VS3 -0.31 0.31 PCT 17 Structure Wear Service U-bend Support Remain In-3 101 58 VS4 0.84 0.42 PCT 19 Structure Wear Service U-bend Support Remain In-3 102 73 VS1 -0.91 0.43 PCT 19 Structure Wear Service U-bend Support Remain In-4 92 81 VS2 0.9 0.71 PCT 23 Structure Wear Service U-bend Support Remain In-4 93 70 VS2 -0.82 0.39 PCT 18 Structure Wear Service U-bend Support Remain In-4 93 70 VS2 0.06 0.37 PCT 18 Structure Wear Service CNL-22-109 E7 of 32

Enclosure Table 5 U1R14 U-bend Support Structure Wear Indications - All SGs

% through SG Row Col Loc Inch Volts Indic wall (TW) Characterization Resolution U-bend Support Remain In-4 93 70 VS2 0.92 0.4 PCT 19 Structure Wear Service U-bend Support Remain In-4 93 80 VS2 0.2 0.31 PCT 17 Structure Wear Service U-bend Support Remain In-4 93 80 VS2 0.96 0.51 PCT 21 Structure Wear Service U-bend Support Remain In-4 96 83 DS2 -0.83 0.45 PCT 20 Structure Wear Service U-bend Support Remain In-4 97 72 VS3 -0.24 0.37 PCT 18 Structure Wear Service U-bend Support Remain In-4 98 47 VS2 0.82 0.21 PCT 15 Structure Wear Service U-bend Support Remain In-4 101 70 VS3 0.61 0.44 PCT 19 Structure Wear Service U-bend Support Remain In-4 102 57 DS2 -0.76 0.5 PCT 21 Structure Wear Service U-bend Support Remain In-4 102 57 VS3 -1.14 0.66 PCT 22 Structure Wear Service Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-1 1 48 H04 -1.06 0.37 PCT 18 Horizontal Grid Wear Service Remain In-1 1 48 H07 0.19 0.32 PCT 17 Horizontal Grid Wear Service Remain In-1 1 116 C04 -0.88 0.35 PCT 18 Horizontal Grid Wear Service Remain In-1 7 64 H09 0.66 0.42 PCT 19 Horizontal Grid Wear Service Remain In-1 7 88 H06 -0.97 0.61 PCT 22 Horizontal Grid Wear Service Remain In-1 7 102 H08 0.63 0.37 PCT 18 Horizontal Grid Wear Service Remain In-1 8 99 H09 -1.06 0.42 PCT 19 Horizontal Grid Wear Service Remain In-1 8 127 C05 -0.67 0.31 PCT 17 Horizontal Grid Wear Service Remain In-1 9 100 C10 -0.87 0.41 PCT 19 Horizontal Grid Wear Service Remain In-1 9 100 C11 0.76 0.36 PCT 18 Horizontal Grid Wear Service Remain In-1 9 104 H07 -0.92 0.65 PCT 22 Horizontal Grid Wear Service Remain In-1 18 103 H07 -0.92 0.47 PCT 20 Horizontal Grid Wear Service Remain In-1 23 84 C11 0.78 0.4 PCT 19 Horizontal Grid Wear Service CNL-22-109 E8 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-1 26 123 C06 -0.7 0.41 PCT 19 Horizontal Grid Wear Service Remain In-1 27 124 C06 -0.84 0.46 PCT 20 Horizontal Grid Wear Service Remain In-1 28 45 C11 0.67 0.39 PCT 19 Horizontal Grid Wear Service Remain In-1 29 124 C05 -0.9 0.33 PCT 17 Horizontal Grid Wear Service Remain In-1 29 124 C06 0.77 0.48 PCT 20 Horizontal Grid Wear Service Remain In-1 34 123 C05 -0.87 0.4 PCT 19 Horizontal Grid Wear Service Remain In-1 59 112 C06 -0.67 0.3 PCT 17 Horizontal Grid Wear Service Remain In-1 60 115 C05 -0.67 0.38 PCT 18 Horizontal Grid Wear Service Remain In-1 67 112 C06 0.83 0.44 PCT 19 Horizontal Grid Wear Service Remain In-1 68 111 C06 0.75 0.36 PCT 18 Horizontal Grid Wear Service Remain In-1 71 110 C06 0.81 0.42 PCT 19 Horizontal Grid Wear Service Remain In-1 76 107 C06 0.62 0.61 PCT 22 Horizontal Grid Wear Service Remain In-1 77 106 C06 0.72 0.39 PCT 18 Horizontal Grid Wear Service Remain In-1 79 104 C03 -0.84 0.34 PCT 17 Horizontal Grid Wear Service Remain In-1 82 103 C04 -0.74 0.24 PCT 15 Horizontal Grid Wear Service Remain In-1 83 26 C03 0.73 0.39 PCT 19 Horizontal Grid Wear Service Remain In-1 83 102 C03 -0.76 0.41 PCT 19 Horizontal Grid Wear Service Remain In-1 83 102 C06 0.67 0.32 PCT 17 Horizontal Grid Wear Service Remain In-1 84 99 C03 -0.76 0.4 PCT 19 Horizontal Grid Wear Service Remain In-1 84 99 C04 0.75 0.61 PCT 22 Horizontal Grid Wear Service Remain In-1 84 99 C07 1 0.39 PCT 18 Horizontal Grid Wear Service Remain In-1 85 30 C03 0.73 0.51 PCT 21 Horizontal Grid Wear Service Remain In-1 85 94 C03 -1 0.35 PCT 18 Horizontal Grid Wear Service Remain In-1 85 98 C04 0.81 0.39 PCT 18 Horizontal Grid Wear Service Remain In-1 85 100 C03 -0.79 1.04 PCT 27 Horizontal Grid Wear Service CNL-22-109 E9 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-1 86 97 C04 0.56 0.31 PCT 17 Horizontal Grid Wear Service Remain In-1 86 99 C03 -0.9 0.37 PCT 18 Horizontal Grid Wear Service Remain In-1 87 30 C02 0.73 0.5 PCT 21 Horizontal Grid Wear Service Remain In-1 87 96 C04 -0.87 0.4 PCT 19 Horizontal Grid Wear Service Remain In-1 87 98 C03 0.76 0.53 PCT 21 Horizontal Grid Wear Service Remain In-1 88 31 C03 0.78 0.34 PCT 17 Horizontal Grid Wear Service Remain In-1 88 95 C03 -0.87 0.66 PCT 22 Horizontal Grid Wear Service Remain In-1 88 97 C03 0.78 0.5 PCT 21 Horizontal Grid Wear Service Remain In-1 89 94 C04 0.73 0.36 PCT 18 Horizontal Grid Wear Service Remain In-1 89 96 C03 -0.79 1.95 PCT 33 Horizontal Grid Wear Service Remain In-1 90 93 C03 -0.75 0.45 PCT 20 Horizontal Grid Wear Service Remain In-1 90 95 C03 -0.78 0.56 PCT 21 Horizontal Grid Wear Service Remain In-1 90 95 C04 0.59 0.58 PCT 22 Horizontal Grid Wear Service Remain In-1 91 90 C04 -0.98 0.41 PCT 19 Horizontal Grid Wear Service Remain In-1 91 92 C03 -0.9 0.41 PCT 19 Horizontal Grid Wear Service Remain In-1 91 94 C06 0.64 0.47 PCT 20 Horizontal Grid Wear Service Remain In-1 92 91 C03 -0.9 0.37 PCT 18 Horizontal Grid Wear Service Remain In-1 92 93 C03 -0.79 0.82 PCT 24 Horizontal Grid Wear Service Remain In-1 95 88 C03 0.75 0.6 PCT 22 Horizontal Grid Wear Service Remain In-1 96 89 C03 -0.93 0.39 PCT 18 Horizontal Grid Wear Service Remain In-1 97 84 C03 -0.79 0.47 PCT 20 Horizontal Grid Wear Service Remain In-1 97 84 C07 0.78 0.51 PCT 21 Horizontal Grid Wear Service Remain In-1 98 85 C03 0.73 0.45 PCT 20 Horizontal Grid Wear Service Remain In-1 98 85 C05 -0.92 0.66 PCT 22 Horizontal Grid Wear Service Remain In-1 100 83 C03 0.75 0.66 PCT 22 Horizontal Grid Wear Service CNL-22-109 E10 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-1 100 83 C05 -0.95 0.73 PCT 23 Horizontal Grid Wear Service Remain In-1 101 66 C03 0.78 0.32 PCT 17 Horizontal Grid Wear Service Remain In-1 101 78 C03 -0.95 0.47 PCT 20 Horizontal Grid Wear Service Remain In-1 102 71 C03 -0.81 0.3 PCT 17 Horizontal Grid Wear Service Remain In-1 102 71 C04 -1 0.26 PCT 16 Horizontal Grid Wear Service Remain In-1 102 79 C03 0.73 0.72 PCT 23 Horizontal Grid Wear Service Remain In-1 103 54 C03 0.95 0.36 PCT 18 Horizontal Grid Wear Service Remain In-1 103 74 C03 0.95 0.37 PCT 18 Horizontal Grid Wear Service Remain In-1 104 63 C03 0.78 0.39 PCT 18 Horizontal Grid Wear Service Remain In-1 105 64 C03 0.75 0.45 PCT 20 Horizontal Grid Wear Service Remain In-1 105 64 C05 -0.92 0.63 PCT 22 Horizontal Grid Wear Service Remain In-2 1 42 H04 -0.8 0.25 PCT 16 Horizontal Grid Wear Service Remain In-2 1 44 H04 -0.86 0.16 PCT 13 Horizontal Grid Wear Service Remain In-2 1 44 H08 -0.91 0.28 PCT 16 Horizontal Grid Wear Service Remain In-2 1 48 H04 0.91 0.3 PCT 17 Horizontal Grid Wear Service Remain In-2 1 70 H05 -0.95 0.25 PCT 16 Horizontal Grid Wear Service Remain In-2 1 74 H04 -0.6 0.37 PCT 18 Horizontal Grid Wear Service Remain In-2 2 31 H06 -0.99 0.43 PCT 19 Horizontal Grid Wear Service Remain In-2 2 41 H07 -0.94 0.33 PCT 17 Horizontal Grid Wear Service Remain In-2 2 53 H05 -0.72 0.28 PCT 16 Horizontal Grid Wear Service Remain In-2 2 69 H04 -0.94 0.33 PCT 17 Horizontal Grid Wear Service Remain In-2 2 73 H04 -0.88 0.25 PCT 16 Horizontal Grid Wear Service Remain In-2 2 101 H06 0.86 0.34 PCT 17 Horizontal Grid Wear Service Remain In-2 6 1 C03 0.81 0.33 PCT 17 Horizontal Grid Wear Service Remain In-2 8 1 C03 0.56 0.37 PCT 18 Horizontal Grid Wear Service CNL-22-109 E11 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-2 8 77 H07 -1.01 0.53 PCT 21 Horizontal Grid Wear Service Remain In-2 8 77 H08 -0.98 0.92 PCT 25 Horizontal Grid Wear Service Remain In-2 8 127 C03 0.76 0.58 PCT 21 Horizontal Grid Wear Service Remain In-2 8 127 C04 0.82 0.66 PCT 22 Horizontal Grid Wear Service Remain In-2 10 127 C03 0.75 0.56 PCT 21 Horizontal Grid Wear Service Remain In-2 14 123 C03 0.92 0.32 PCT 17 Horizontal Grid Wear Service Remain In-2 18 73 H07 -1.04 0.41 PCT 19 Horizontal Grid Wear Service Remain In-2 19 124 C03 0.76 0.32 PCT 17 Horizontal Grid Wear Service Remain In-2 19 124 C05 -0.93 0.39 PCT 18 Horizontal Grid Wear Service Remain In-2 19 126 C03 0.79 0.33 PCT 17 Horizontal Grid Wear Service Remain In-2 20 123 C03 0.86 0.39 PCT 18 Horizontal Grid Wear Service Remain In-2 21 122 C09 -1.04 0.46 PCT 20 Horizontal Grid Wear Service Remain In-2 22 123 C03 0.73 1.4 PCT 30 Horizontal Grid Wear Service Remain In-2 22 123 C05 0.64 0.38 PCT 18 Horizontal Grid Wear Service Remain In-2 22 123 C06 -1.07 0.36 PCT 18 Horizontal Grid Wear Service Remain In-2 22 123 C07 -0.92 0.71 PCT 23 Horizontal Grid Wear Service Remain In-2 22 123 C07 0.76 0.67 PCT 23 Horizontal Grid Wear Service Remain In-2 22 125 C03 0.7 0.37 PCT 18 Horizontal Grid Wear Service Remain In-2 22 125 C06 0.73 0.37 PCT 18 Horizontal Grid Wear Service Remain In-2 23 44 C12 0.67 0.46 PCT 20 Horizontal Grid Wear Service Remain In-2 23 48 C12 -0.84 0.33 PCT 17 Horizontal Grid Wear Service Remain In-2 23 122 C03 0.76 0.62 PCT 22 Horizontal Grid Wear Service Remain In-2 25 28 C12 -0.79 0.16 PCT 13 Horizontal Grid Wear Service Remain In-2 25 122 C03 0.76 0.74 PCT 23 Horizontal Grid Wear Service Remain In-2 26 123 C03 -0.95 0.34 PCT 18 Horizontal Grid Wear Service CNL-22-109 E12 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-2 26 123 C03 0.65 0.58 PCT 21 Horizontal Grid Wear Service Remain In-2 26 123 C04 0.64 0.42 PCT 19 Horizontal Grid Wear Service Remain In-2 26 125 C03 0.7 0.38 PCT 18 Horizontal Grid Wear Service Remain In-2 27 4 C06 -1.04 0.21 PCT 15 Horizontal Grid Wear Service Remain In-2 27 124 C03 0.81 0.5 PCT 21 Horizontal Grid Wear Service Remain In-2 27 124 C05 -0.98 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 28 119 C06 -0.82 0.51 PCT 21 Horizontal Grid Wear Service Remain In-2 28 123 C03 0.78 0.98 PCT 26 Horizontal Grid Wear Service Remain In-2 30 7 C06 0.76 0.26 PCT 16 Horizontal Grid Wear Service Remain In-2 30 123 C03 0.73 0.94 PCT 26 Horizontal Grid Wear Service Remain In-2 30 123 C04 0.65 0.39 PCT 18 Horizontal Grid Wear Service Remain In-2 30 123 C05 -0.89 0.71 PCT 23 Horizontal Grid Wear Service Remain In-2 30 123 C06 -0.84 0.46 PCT 20 Horizontal Grid Wear Service Remain In-2 30 123 C06 0.84 1.05 PCT 27 Horizontal Grid Wear Service Remain In-2 30 123 C07 -0.86 1.12 PCT 27 Horizontal Grid Wear Service Remain In-2 31 54 C12 -1.03 0.59 PCT 22 Horizontal Grid Wear Service Remain In-2 32 121 C03 0.73 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 32 121 C05 -0.93 0.36 PCT 18 Horizontal Grid Wear Service Remain In-2 33 122 C03 -0.9 0.42 PCT 19 Horizontal Grid Wear Service Remain In-2 33 122 C04 0.73 0.39 PCT 18 Horizontal Grid Wear Service Remain In-2 33 122 C07 0.53 0.36 PCT 18 Horizontal Grid Wear Service Remain In-2 36 7 C06 -0.84 0.35 PCT 18 Horizontal Grid Wear Service Remain In-2 36 121 C03 -0.92 0.45 PCT 20 Horizontal Grid Wear Service Remain In-2 37 8 C03 0.75 0.35 PCT 18 Horizontal Grid Wear Service Remain In-2 38 7 C03 0.94 0.27 PCT 16 Horizontal Grid Wear Service CNL-22-109 E13 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-2 39 8 C07 -1.07 0.2 PCT 15 Horizontal Grid Wear Service Remain In-2 47 10 C03 0.88 0.39 PCT 19 Horizontal Grid Wear Service Remain In-2 50 9 C04 -0.9 0.42 PCT 19 Horizontal Grid Wear Service Remain In-2 51 118 C03 -0.98 0.34 PCT 18 Horizontal Grid Wear Service Remain In-2 53 118 C03 -0.89 0.5 PCT 21 Horizontal Grid Wear Service Remain In-2 59 114 C04 0.62 0.22 PCT 15 Horizontal Grid Wear Service Remain In-2 60 115 C03 -0.96 0.41 PCT 19 Horizontal Grid Wear Service Remain In-2 60 115 C06 -1.12 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 60 115 C07 -1.01 0.32 PCT 17 Horizontal Grid Wear Service Remain In-2 62 15 C04 -1.03 0.31 PCT 17 Horizontal Grid Wear Service Remain In-2 62 15 C05 0.67 0.42 PCT 19 Horizontal Grid Wear Service Remain In-2 62 113 C03 -0.95 0.35 PCT 18 Horizontal Grid Wear Service Remain In-2 62 113 C04 0.62 0.37 PCT 18 Horizontal Grid Wear Service Remain In-2 62 113 C07 -0.98 0.88 PCT 25 Horizontal Grid Wear Service Remain In-2 63 114 C03 -1.04 0.29 PCT 17 Horizontal Grid Wear Service Remain In-2 63 114 C06 0.64 0.2 PCT 15 Horizontal Grid Wear Service Remain In-2 64 113 C03 -0.87 0.31 PCT 17 Horizontal Grid Wear Service Remain In-2 71 110 C05 0.65 0.28 PCT 16 Horizontal Grid Wear Service Remain In-2 72 109 C03 -1.2 0.48 PCT 20 Horizontal Grid Wear Service Remain In-2 76 107 C03 0.65 0.28 PCT 16 Horizontal Grid Wear Service Remain In-2 77 104 C03 -0.76 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 77 104 C04 -1.01 0.37 PCT 18 Horizontal Grid Wear Service Remain In-2 78 105 C03 -0.82 0.37 PCT 18 Horizontal Grid Wear Service Remain In-2 79 104 C03 -1.04 0.37 PCT 18 Horizontal Grid Wear Service Remain In-2 79 104 C04 -0.96 0.31 PCT 17 Horizontal Grid Wear Service CNL-22-109 E14 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-2 80 103 C06 -0.95 0.42 PCT 19 Horizontal Grid Wear Service Remain In-2 83 100 C04 0.54 0.48 PCT 20 Horizontal Grid Wear Service Remain In-2 85 100 C04 0.65 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 85 100 C06 -0.99 0.51 PCT 21 Horizontal Grid Wear Service Remain In-2 85 100 C07 -1.22 0.34 PCT 18 Horizontal Grid Wear Service Remain In-2 86 97 C03 0.68 0.31 PCT 17 Horizontal Grid Wear Service Remain In-2 86 97 C04 0.89 0.36 PCT 18 Horizontal Grid Wear Service Remain In-2 86 99 C04 0.7 0.63 PCT 22 Horizontal Grid Wear Service Remain In-2 87 30 C03 0.74 0.38 PCT 18 Horizontal Grid Wear Service Remain In-2 87 32 C06 -1.72 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 87 94 C04 0.73 0.46 PCT 20 Horizontal Grid Wear Service Remain In-2 87 98 C03 -0.95 0.71 PCT 23 Horizontal Grid Wear Service Remain In-2 87 98 C04 0.67 0.41 PCT 19 Horizontal Grid Wear Service Remain In-2 87 98 C06 -0.95 1.35 PCT 30 Horizontal Grid Wear Service Remain In-2 88 95 C03 -1.04 2.46 PCT 37 Horizontal Grid Wear Service Remain In-2 88 95 C03 0.53 0.27 PCT 16 Horizontal Grid Wear Service Remain In-2 88 95 C06 0.78 0.26 PCT 16 Horizontal Grid Wear Service Remain In-2 89 32 C03 -0.94 0.42 PCT 19 Horizontal Grid Wear Service Remain In-2 89 32 C03 0.82 0.28 PCT 16 Horizontal Grid Wear Service Remain In-2 89 94 C03 -0.98 0.87 PCT 25 Horizontal Grid Wear Service Remain In-2 89 96 C06 -1.04 0.29 PCT 17 Horizontal Grid Wear Service Remain In-2 90 95 C04 0.73 0.75 PCT 23 Horizontal Grid Wear Service Remain In-2 90 95 C07 -0.95 0.35 PCT 18 Horizontal Grid Wear Service Remain In-2 91 94 C03 -0.92 0.87 PCT 25 Horizontal Grid Wear Service Remain In-2 92 35 C03 -0.92 0.26 PCT 16 Horizontal Grid Wear Service CNL-22-109 E15 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-2 92 35 C04 -0.86 0.32 PCT 17 Horizontal Grid Wear Service Remain In-2 92 93 C04 0.73 0.38 PCT 18 Horizontal Grid Wear Service Remain In-2 92 93 C06 -0.88 0.36 PCT 18 Horizontal Grid Wear Service Remain In-2 92 93 C07 -0.87 0.41 PCT 19 Horizontal Grid Wear Service Remain In-2 95 82 C03 -1.15 0.33 PCT 17 Horizontal Grid Wear Service Remain In-2 96 85 C06 0.89 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 96 85 C07 -1.06 0.33 PCT 17 Horizontal Grid Wear Service Remain In-2 96 87 C03 -0.82 0.39 PCT 18 Horizontal Grid Wear Service Remain In-2 97 86 C03 -1.12 0.43 PCT 19 Horizontal Grid Wear Service Remain In-2 97 88 C03 -0.96 0.47 PCT 20 Horizontal Grid Wear Service Remain In-2 98 43 C05 0.71 0.49 PCT 20 Horizontal Grid Wear Service Remain In-2 98 79 C03 -1.12 0.4 PCT 19 Horizontal Grid Wear Service Remain In-2 98 83 C03 -1.18 0.39 PCT 18 Horizontal Grid Wear Service Remain In-2 99 84 C02 0.62 0.24 PCT 16 Horizontal Grid Wear Service Remain In-2 100 81 C04 0.78 0.76 PCT 23 Horizontal Grid Wear Service Remain In-2 101 78 C03 -1.15 0.49 PCT 20 Horizontal Grid Wear Service Remain In-2 101 80 C03 -1.2 0.45 PCT 20 Horizontal Grid Wear Service Remain In-2 103 62 C03 0.92 0.34 PCT 17 Horizontal Grid Wear Service Remain In-2 103 66 C05 0.67 0.59 PCT 22 Horizontal Grid Wear Service Remain In-2 103 74 C03 -1.15 0.41 PCT 19 Horizontal Grid Wear Service Remain In-2 104 61 C06 -0.9 0.25 PCT 16 Horizontal Grid Wear Service Remain In-2 104 69 C05 0.7 0.39 PCT 19 Horizontal Grid Wear Service Remain In-2 105 66 C03 0.72 0.68 PCT 23 Horizontal Grid Wear Service Remain In-2 105 66 C05 0.67 0.34 PCT 17 Horizontal Grid Wear Service Remain In-2 105 68 C03 0.75 0.49 PCT 20 Horizontal Grid Wear Service CNL-22-109 E16 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-3 1 72 H04 -0.88 0.23 PCT 15 Horizontal Grid Wear Service Remain In-3 1 72 H04 0.91 0.16 PCT 13 Horizontal Grid Wear Service Remain In-3 1 72 H05 -0.96 0.19 PCT 14 Horizontal Grid Wear Service Remain In-3 1 78 H04 -0.91 0.45 PCT 20 Horizontal Grid Wear Service Remain In-3 1 86 H04 -0.85 0.2 PCT 15 Horizontal Grid Wear Service Remain In-3 7 2 C03 0.83 0.27 PCT 16 Horizontal Grid Wear Service Remain In-3 9 106 C06 -0.78 0.36 PCT 18 Horizontal Grid Wear Service Remain In-3 10 1 C03 0.72 0.7 PCT 23 Horizontal Grid Wear Service Remain In-3 10 1 C05 -0.92 0.31 PCT 17 Horizontal Grid Wear Service Remain In-3 13 4 C03 0.75 0.37 PCT 18 Horizontal Grid Wear Service Remain In-3 14 51 C11 -1.06 0.32 PCT 17 Horizontal Grid Wear Service Remain In-3 14 51 H10 0.68 0.36 PCT 18 Horizontal Grid Wear Service Remain In-3 14 81 H06 -0.9 0.35 PCT 18 Horizontal Grid Wear Service Remain In-3 15 2 C03 0.83 0.32 PCT 17 Horizontal Grid Wear Service Remain In-3 15 2 C04 -0.97 0.46 PCT 20 Horizontal Grid Wear Service Remain In-3 15 4 C06 -0.91 0.4 PCT 19 Horizontal Grid Wear Service Remain In-3 17 102 C12 -1.06 0.48 PCT 20 Horizontal Grid Wear Service Remain In-3 17 102 C12 0.66 0.37 PCT 18 Horizontal Grid Wear Service Remain In-3 18 53 C12 -0.89 0.33 PCT 17 Horizontal Grid Wear Service Remain In-3 19 2 C04 -0.98 0.75 PCT 23 Horizontal Grid Wear Service Remain In-3 20 61 C10 -0.98 0.42 PCT 19 Horizontal Grid Wear Service Remain In-3 23 124 C06 0.69 0.73 PCT 23 Horizontal Grid Wear Service Remain In-3 24 3 C05 0.8 0.35 PCT 18 Horizontal Grid Wear Service Remain In-3 26 5 C03 -0.8 0.38 PCT 18 Horizontal Grid Wear Service Remain In-3 28 119 C12 -0.86 0.37 PCT 18 Horizontal Grid Wear Service CNL-22-109 E17 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-3 32 5 C03 -0.89 0.36 PCT 18 Horizontal Grid Wear Service Remain In-3 34 5 C03 -1 0.46 PCT 20 Horizontal Grid Wear Service Remain In-3 53 118 C06 0.69 0.29 PCT 16 Horizontal Grid Wear Service Remain In-3 59 14 C03 -1.03 0.56 PCT 21 Horizontal Grid Wear Service Remain In-3 61 114 C06 -0.75 0.33 PCT 17 Horizontal Grid Wear Service Remain In-3 61 114 C06 0.83 0.98 PCT 26 Horizontal Grid Wear Service Remain In-3 64 17 C03 -0.89 0.29 PCT 16 Horizontal Grid Wear Service Remain In-3 64 111 C04 -0.77 0.36 PCT 18 Horizontal Grid Wear Service Remain In-3 64 111 C07 -1 0.18 PCT 14 Horizontal Grid Wear Service Remain In-3 65 18 C03 -0.98 0.38 PCT 18 Horizontal Grid Wear Service Remain In-3 67 112 C06 -1.11 0.28 PCT 16 Horizontal Grid Wear Service Remain In-3 68 19 C03 0.63 0.36 PCT 18 Horizontal Grid Wear Service Remain In-3 71 104 C03 0.87 0.3 PCT 17 Horizontal Grid Wear Service Remain In-3 76 107 C04 0.75 0.56 PCT 21 Horizontal Grid Wear Service Remain In-3 76 107 C06 0.8 0.44 PCT 20 Horizontal Grid Wear Service Remain In-3 77 22 C03 0.72 0.26 PCT 16 Horizontal Grid Wear Service Remain In-3 79 24 C03 0.75 0.36 PCT 18 Horizontal Grid Wear Service Remain In-3 82 25 C03 0.69 0.25 PCT 16 Horizontal Grid Wear Service Remain In-3 82 27 C03 0.67 0.28 PCT 16 Horizontal Grid Wear Service Remain In-3 83 26 C03 0.95 0.24 PCT 15 Horizontal Grid Wear Service Remain In-3 84 29 C03 0.72 0.45 PCT 20 Horizontal Grid Wear Service Remain In-3 84 95 C05 0.91 0.27 PCT 16 Horizontal Grid Wear Service Remain In-3 84 99 C03 -0.92 0.31 PCT 17 Horizontal Grid Wear Service Remain In-3 85 28 C03 0.75 0.58 PCT 21 Horizontal Grid Wear Service Remain In-3 85 96 C03 0.8 0.34 PCT 18 Horizontal Grid Wear Service CNL-22-109 E18 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-3 85 98 C02 -0.94 0.66 PCT 22 Horizontal Grid Wear Service Remain In-3 86 31 C03 0.66 0.3 PCT 17 Horizontal Grid Wear Service Remain In-3 86 95 C03 0.71 0.46 PCT 20 Horizontal Grid Wear Service Remain In-3 86 97 C02 -0.82 0.58 PCT 22 Horizontal Grid Wear Service Remain In-3 86 99 C02 -0.85 0.53 PCT 21 Horizontal Grid Wear Service Remain In-3 86 99 C03 -0.89 0.29 PCT 17 Horizontal Grid Wear Service Remain In-3 86 99 C04 0.62 0.38 PCT 18 Horizontal Grid Wear Service Remain In-3 86 99 C05 0.74 0.66 PCT 22 Horizontal Grid Wear Service Remain In-3 89 32 C03 0.69 0.38 PCT 18 Horizontal Grid Wear Service Remain In-3 89 96 C03 -0.92 0.66 PCT 22 Horizontal Grid Wear Service Remain In-3 90 33 C03 0.66 0.57 PCT 21 Horizontal Grid Wear Service Remain In-3 90 93 C04 -0.97 0.22 PCT 15 Horizontal Grid Wear Service Remain In-3 90 95 C03 -0.8 0.32 PCT 17 Horizontal Grid Wear Service Remain In-3 90 95 C04 -0.85 0.38 PCT 18 Horizontal Grid Wear Service Remain In-3 91 34 C03 -0.92 0.91 PCT 25 Horizontal Grid Wear Service Remain In-3 92 35 C03 -0.98 0.93 PCT 25 Horizontal Grid Wear Service Remain In-3 92 91 C03 -0.83 0.42 PCT 19 Horizontal Grid Wear Service Remain In-3 92 91 C05 -0.95 0.27 PCT 16 Horizontal Grid Wear Service Remain In-3 92 93 C04 -0.98 0.31 PCT 17 Horizontal Grid Wear Service Remain In-3 93 36 C03 -0.89 0.37 PCT 18 Horizontal Grid Wear Service Remain In-3 93 36 C04 0.69 0.38 PCT 18 Horizontal Grid Wear Service Remain In-3 93 90 C03 0.8 0.39 PCT 19 Horizontal Grid Wear Service Remain In-3 94 37 C06 -0.92 0.43 PCT 19 Horizontal Grid Wear Service Remain In-3 94 41 C07 -1.12 0.55 PCT 21 Horizontal Grid Wear Service Remain In-3 94 89 C03 -0.92 0.37 PCT 18 Horizontal Grid Wear Service CNL-22-109 E19 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-3 95 38 C02 -0.77 0.43 PCT 19 Horizontal Grid Wear Service Remain In-3 95 38 C04 0.69 0.33 PCT 17 Horizontal Grid Wear Service Remain In-3 96 85 C06 0.79 0.43 PCT 19 Horizontal Grid Wear Service Remain In-3 97 40 C04 0.72 0.29 PCT 16 Horizontal Grid Wear Service Remain In-3 97 42 C04 0.69 1.03 PCT 26 Horizontal Grid Wear Service Remain In-3 97 42 C06 0.86 0.28 PCT 16 Horizontal Grid Wear Service Remain In-3 100 75 C03 0.72 0.37 PCT 18 Horizontal Grid Wear Service Remain In-3 101 68 C03 0.8 0.52 PCT 21 Horizontal Grid Wear Service Remain In-4 3 42 C11 -0.96 0.75 PCT 23 Horizontal Grid Wear Service Remain In-4 3 42 C12 -1.09 0.42 PCT 19 Horizontal Grid Wear Service Remain In-4 6 37 C11 -1.01 0.32 PCT 17 Horizontal Grid Wear Service Remain In-4 6 73 H07 -0.87 0.53 PCT 21 Horizontal Grid Wear Service Remain In-4 6 127 C03 0.76 0.75 PCT 23 Horizontal Grid Wear Service Remain In-4 9 40 C11 -0.96 0.29 PCT 17 Horizontal Grid Wear Service Remain In-4 9 42 H06 0.62 0.8 PCT 24 Horizontal Grid Wear Service Remain In-4 9 42 H07 0.72 0.31 PCT 17 Horizontal Grid Wear Service Remain In-4 10 41 C09 -0.87 0.41 PCT 19 Horizontal Grid Wear Service Remain In-4 10 61 H07 -1.12 0.38 PCT 18 Horizontal Grid Wear Service Remain In-4 12 71 H06 -0.86 0.61 PCT 22 Horizontal Grid Wear Service Remain In-4 12 71 H07 -1.23 0.61 PCT 22 Horizontal Grid Wear Service Remain In-4 13 78 C10 0.64 1.57 PCT 31 Horizontal Grid Wear Service Remain In-4 14 3 C04 0.69 0.44 PCT 20 Horizontal Grid Wear Service Remain In-4 18 63 C11 0.64 0.53 PCT 21 Horizontal Grid Wear Service Remain In-4 18 63 C12 0.61 0.71 PCT 23 Horizontal Grid Wear Service Remain In-4 22 123 C03 -1.1 0.37 PCT 18 Horizontal Grid Wear Service CNL-22-109 E20 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-4 23 124 C03 -0.88 0.55 PCT 21 Horizontal Grid Wear Service Remain In-4 23 124 C06 -0.84 0.56 PCT 21 Horizontal Grid Wear Service Remain In-4 24 91 H06 -0.22 0.43 PCT 19 Horizontal Grid Wear Service Remain In-4 24 125 C03 0.87 0.76 PCT 24 Horizontal Grid Wear Service Remain In-4 24 125 C06 0.75 0.35 PCT 18 Horizontal Grid Wear Service Remain In-4 25 62 C11 0.67 0.48 PCT 20 Horizontal Grid Wear Service Remain In-4 26 35 C12 -0.92 0.31 PCT 17 Horizontal Grid Wear Service Remain In-4 26 123 C03 -0.9 0.37 PCT 18 Horizontal Grid Wear Service Remain In-4 26 123 C04 0.76 0.5 PCT 21 Horizontal Grid Wear Service Remain In-4 26 123 C08 -0.93 0.42 PCT 19 Horizontal Grid Wear Service Remain In-4 27 124 C03 -0.93 0.72 PCT 23 Horizontal Grid Wear Service Remain In-4 28 123 C04 -0.87 0.44 PCT 20 Horizontal Grid Wear Service Remain In-4 30 5 C05 -0.78 0.35 PCT 18 Horizontal Grid Wear Service Remain In-4 31 124 C03 -0.93 0.45 PCT 20 Horizontal Grid Wear Service Remain In-4 32 5 C02 0.76 0.32 PCT 17 Horizontal Grid Wear Service Remain In-4 32 7 C02 0.82 0.46 PCT 20 Horizontal Grid Wear Service Remain In-4 32 7 C03 0.73 0.39 PCT 18 Horizontal Grid Wear Service Remain In-4 33 8 C03 0.94 0.36 PCT 18 Horizontal Grid Wear Service Remain In-4 35 122 C03 0.97 0.46 PCT 20 Horizontal Grid Wear Service Remain In-4 43 8 C04 0.98 0.41 PCT 19 Horizontal Grid Wear Service Remain In-4 44 9 C06 -0.7 0.38 PCT 18 Horizontal Grid Wear Service Remain In-4 44 121 C03 1 0.62 PCT 22 Horizontal Grid Wear Service Remain In-4 45 8 C03 -0.82 0.38 PCT 18 Horizontal Grid Wear Service Remain In-4 49 110 C12 -0.48 0.38 PCT 18 Horizontal Grid Wear Service Remain In-4 50 87 H01 -1.22 0.41 PCT 19 Horizontal Grid Wear Service CNL-22-109 E21 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-4 53 118 C02 -0.87 0.5 PCT 21 Horizontal Grid Wear Service Remain In-4 60 115 C07 0.9 0.39 PCT 18 Horizontal Grid Wear Service Remain In-4 63 114 C06 -1.11 0.52 PCT 21 Horizontal Grid Wear Service Remain In-4 65 112 C05 -0.84 0.44 PCT 19 Horizontal Grid Wear Service Remain In-4 71 108 C06 0.73 0.27 PCT 16 Horizontal Grid Wear Service Remain In-4 77 104 C03 0.71 1.01 PCT 26 Horizontal Grid Wear Service Remain In-4 78 103 C03 0.8 0.36 PCT 18 Horizontal Grid Wear Service Remain In-4 83 98 C03 0.71 0.35 PCT 18 Horizontal Grid Wear Service Remain In-4 83 98 C04 -0.9 0.27 PCT 16 Horizontal Grid Wear Service Remain In-4 83 100 C03 0.72 0.45 PCT 20 Horizontal Grid Wear Service Remain In-4 84 97 C03 0.74 0.4 PCT 19 Horizontal Grid Wear Service Remain In-4 84 97 C04 -0.94 0.45 PCT 20 Horizontal Grid Wear Service Remain In-4 84 101 C02 0.68 0.45 PCT 20 Horizontal Grid Wear Service Remain In-4 84 101 C03 0.71 0.53 PCT 21 Horizontal Grid Wear Service Remain In-4 84 101 C04 -0.94 0.62 PCT 22 Horizontal Grid Wear Service Remain In-4 84 101 C06 -0.91 0.36 PCT 18 Horizontal Grid Wear Service Remain In-4 85 28 C03 -0.86 0.62 PCT 22 Horizontal Grid Wear Service Remain In-4 85 94 C03 -0.84 0.47 PCT 20 Horizontal Grid Wear Service Remain In-4 85 96 C04 -0.95 0.39 PCT 18 Horizontal Grid Wear Service Remain In-4 85 100 C04 -0.86 0.45 PCT 20 Horizontal Grid Wear Service Remain In-4 87 92 C04 0.78 0.41 PCT 19 Horizontal Grid Wear Service Remain In-4 87 96 C03 -0.89 0.81 PCT 24 Horizontal Grid Wear Service Remain In-4 87 96 C05 -0.72 0.43 PCT 19 Horizontal Grid Wear Service Remain In-4 87 98 C04 -0.89 0.49 PCT 20 Horizontal Grid Wear Service Remain In-4 88 31 C03 -0.95 0.61 PCT 22 Horizontal Grid Wear Service CNL-22-109 E22 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-4 88 95 C03 -0.75 0.3 PCT 17 Horizontal Grid Wear Service Remain In-4 89 94 C05 0.66 0.3 PCT 17 Horizontal Grid Wear Service Remain In-4 89 96 C03 -0.89 0.68 PCT 23 Horizontal Grid Wear Service Remain In-4 89 96 C05 0.71 0.36 PCT 18 Horizontal Grid Wear Service Remain In-4 90 35 C03 -1.18 0.41 PCT 19 Horizontal Grid Wear Service Remain In-4 90 39 C04 0.88 0.33 PCT 17 Horizontal Grid Wear Service Remain In-4 90 91 C04 -0.92 0.36 PCT 18 Horizontal Grid Wear Service Remain In-4 91 34 C03 -0.89 0.82 PCT 24 Horizontal Grid Wear Service Remain In-4 91 34 C05 0.74 0.49 PCT 20 Horizontal Grid Wear Service Remain In-4 91 36 C03 -1.2 0.52 PCT 21 Horizontal Grid Wear Service Remain In-4 91 36 C04 0.71 0.58 PCT 22 Horizontal Grid Wear Service Remain In-4 91 38 C03 -0.92 0.59 PCT 22 Horizontal Grid Wear Service Remain In-4 91 92 C04 -0.8 0.49 PCT 20 Horizontal Grid Wear Service Remain In-4 91 94 C03 0.71 0.7 PCT 23 Horizontal Grid Wear Service Remain In-4 92 37 C03 -0.86 0.85 PCT 25 Horizontal Grid Wear Service Remain In-4 92 91 C03 0.65 0.29 PCT 17 Horizontal Grid Wear Service Remain In-4 92 93 C03 0.74 0.46 PCT 20 Horizontal Grid Wear Service Remain In-4 93 36 C03 -0.74 0.59 PCT 22 Horizontal Grid Wear Service Remain In-4 93 36 C05 0.68 0.52 PCT 21 Horizontal Grid Wear Service Remain In-4 94 37 C03 -1.17 1.99 PCT 34 Horizontal Grid Wear Service Remain In-4 94 39 C03 -0.86 0.59 PCT 22 Horizontal Grid Wear Service Remain In-4 94 39 C07 -0.92 0.37 PCT 18 Horizontal Grid Wear Service Remain In-4 94 41 C03 -0.92 0.71 PCT 23 Horizontal Grid Wear Service Remain In-4 95 40 C05 0.71 0.4 PCT 19 Horizontal Grid Wear Service Remain In-4 95 40 C06 -1.03 0.37 PCT 18 Horizontal Grid Wear Service CNL-22-109 E23 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-4 95 42 C03 -0.83 0.96 PCT 26 Horizontal Grid Wear Service Remain In-4 95 86 C03 0.68 0.78 PCT 24 Horizontal Grid Wear Service Remain In-4 96 41 C03 0.71 0.64 PCT 22 Horizontal Grid Wear Service Remain In-4 96 41 C05 -0.98 0.4 PCT 19 Horizontal Grid Wear Service Remain In-4 96 43 C03 -0.95 0.43 PCT 19 Horizontal Grid Wear Service Remain In-4 96 45 C03 -0.92 0.52 PCT 21 Horizontal Grid Wear Service Remain In-4 96 81 C03 0.92 0.38 PCT 18 Horizontal Grid Wear Service Remain In-4 97 42 C05 -0.97 0.66 PCT 22 Horizontal Grid Wear Service Remain In-4 97 78 C03 0.81 0.5 PCT 21 Horizontal Grid Wear Service Remain In-4 97 86 C03 0.74 0.94 PCT 25 Horizontal Grid Wear Service Remain In-4 97 88 C03 -0.74 0.35 PCT 18 Horizontal Grid Wear Service Remain In-4 97 88 C03 0.8 0.51 PCT 21 Horizontal Grid Wear Service Remain In-4 97 88 C07 -0.86 0.36 PCT 18 Horizontal Grid Wear Service Remain In-4 98 43 C03 -0.95 0.36 PCT 18 Horizontal Grid Wear Service Remain In-4 98 43 C07 0.77 0.4 PCT 19 Horizontal Grid Wear Service Remain In-4 98 45 C03 -0.94 1.41 PCT 30 Horizontal Grid Wear Service Remain In-4 98 81 C03 0.59 0.39 PCT 18 Horizontal Grid Wear Service Remain In-4 98 85 C03 0.71 0.73 PCT 23 Horizontal Grid Wear Service Remain In-4 99 44 C03 0.88 0.43 PCT 19 Horizontal Grid Wear Service Remain In-4 99 44 C06 0.79 0.3 PCT 17 Horizontal Grid Wear Service Remain In-4 99 44 C08 0.71 0.31 PCT 17 Horizontal Grid Wear Service Remain In-4 99 46 C03 -0.89 0.59 PCT 22 Horizontal Grid Wear Service Remain In-4 100 81 C03 0.7 0.39 PCT 18 Horizontal Grid Wear Service Remain In-4 100 83 C03 -0.86 0.51 PCT 21 Horizontal Grid Wear Service Remain In-4 100 83 C07 -1.17 0.35 PCT 18 Horizontal Grid Wear Service CNL-22-109 E24 of 32

Enclosure Table 6 U1R14 Horizontal Tube Support Grid Wear Indications - All SGs SG Row Col Loc Inch Volts Indic %TW Characterization Resolution Remain In-4 101 80 C03 0.7 0.45 PCT 20 Horizontal Grid Wear Service Remain In-4 102 49 C03 0.8 0.56 PCT 21 Horizontal Grid Wear Service Remain In-4 102 51 C04 0.78 0.43 PCT 19 Horizontal Grid Wear Service Remain In-4 102 79 C03 0.73 0.4 PCT 19 Horizontal Grid Wear Service Remain In-4 103 76 C03 0.67 0.51 PCT 21 Horizontal Grid Wear Service Remain In-4 104 71 C03 -0.9 0.75 PCT 23 Horizontal Grid Wear Service

6. A description of the condition monitoring assessment and results, including the margin to the tube integrity performance criteria and comparison with the margin predicted to exist at the inspection by the previous forward-looking tube integrity assessment (TS 5.9.9.c.3). Discuss any degradation that was not bounded by the prior operational assessment in terms of projected maximum flaw dimensions, minimum burst strength, and/or accident induced leak rate. Provide details of any in situ pressure test.

A condition monitoring (CM) assessment was performed as required by the WBN Unit 1 SG program. The only tube degradation detected during the U1R14 inspection was wear at tube support structures. This can be sub-divided into U-bend support structure wear and advanced tube support grid (ATSG) wear.

The bobbin probe sizing of the largest U-bend support structure wear indication observed during U1R14 was measured at 27%TW in SG3 tube R81C56 at VS4+0.89 inch. The U1R11 operational assessment (OA) projection was made assuming a duration of 8.6 EFPY between inspections. Using the actual operating interval between inspections of 4.03 EFPY, the worst-case projected U-bend wear indication would have been 31%TW at the U1R14 inspection. Therefore, the growth rate projection method applied in the prior OA is validated. Satisfaction of structural integrity implies satisfaction of leakage integrity at accident condition because steam line break accident condition pressure differential for pop-through is much smaller than 3PNO for pressure-only loading of volumetric flaws.

Therefore, CM has been satisfied for degradation associated with U-bend support structure wear indications during the U1R14 inspection.

The bobbin probe sizing of the largest ATSG wear indication observed during U1R14 was measured at 37%TW, which occurred in SG2 Tube R88C95 at C03-1.04 inches. The U1R11 OA projection was made assuming duration of 8.6 EFPY between inspections.

Using the actual operating interval between inspections of 4.03 EFPY, the worst-case projected horizontal ATSG wear indication would have been 45%TW at the U1R14 inspection. Therefore, the growth rate projection methods applied in the prior OA are validated. Satisfaction of structural integrity implies satisfaction of leakage integrity at accident conditions because steam line break accident condition pressure differential for pop-through is much smaller than 3PNO for pressure-only loading of volumetric flaws.

Therefore, CM has been satisfied for degradation associated with ATSG support structure CNL-22-109 E25 of 32

Enclosure wear indications for the WBN U1R14 inspection.

No in-situ pressure testing was performed, and the indications were bounded by the prior operational assessment.

7. The number of tubes plugged during the inspection outage (TS 5.9.9.c.4). Also, provide the tube location and reason for plugging.

There were no tubes required to be plugged or repaired during U1R14.

8. An analysis summary of the tube integrity conditions predicted to exist at the next scheduled inspection (the forward-looking tube integrity assessment) relative to the applicable performance criteria, including the analysis methodology, inputs, and results (TS 5.9.9.d). The effective full power months of operation permitted for the current operational assessment.

For consistency with the other sections in this enclosure and the U1R14 CMOA, the information in this section is provided in EFPY rather than EFPM. In order to determine growth rates for U-bend support structure wear, an eddy current data history review was performed by the lead eddy current analyst for the U-bend support structure wear indications measuring 20%TW or greater and a sampling of indications below this threshold.

The purpose was to determine whether a measurable precursor signal was present, but unreported in the prior inspection and to determine the associated growth rate for use on the OA projections. As previously noted, TVA discovered a 1% error in the EFPY utilized for the generation of the CMOA (i.e., 4.07 EFPY, the correct value is 4.03 EFPY). The 3P performance criteria burst pressure is 3798 pounds per square inch (psi).

The growth rates are determined based on an operating duration of 4.03 EFPY from U1R11 to U1R14 and normalizing to a %TW/EFPY basis. A summary of growth rates for the U-bend support structure wear indications in the four SGs is provided in Table 7.

Table 7 U-bend Support Structure Wear Growth Comparison SG Number of Max Ave Growth Standard Upper 95th Indications Indication (%TW/EFPY) Deviation Percentile

(%TW) (%TW/EFPY) (%TW/EFPY) 1 13 21 4.57 0.54 5.46 2 11 24 1.99 2.13 5.50 3 23 27 3.90 2.00 7.18 4 12 23 2.90 2.26 6.62 All 59 27 3.42 2.06 6.81 The Westinghouse software W-VOL was utilized to determine an inspection interval. The W-VOL code applies a volume-based approach towards calculating wear over time. This method can project a flaw growth that is based on the applicable work function that actually occurs with the mechanical wear experienced in the SGs. The U1R14 U-bend support structure wear population are assumed to be of flat wear morphology and conservatively assumed to be 2.5 inches in length. Many of the U-bend support structure wear indications have an axial extent far less than this bounding length. From a review of the eddy current CNL-22-109 E26 of 32

Enclosure testing (ECT) graphic for the indication at R81C56 VS4 in SG3, the actual axial extent of the flaw was measured to be 0.4 inches. Because this was the limiting flaw in SG3, and the OA for this SG was close in margin to the performance criteria when using the bounding length (i.e., 2.5 inches) for the indications, the length for this indication only was reduced to be 1.2 inches (0.4 inches for the measured length plus 0.1 in/EFPY of growth, for 7.1 EFPY, rounded up to the assumed length of 1.2 inches). The bounding flaw length of 2.5 inches was used for the other U-bend support structure wear indications in the SGs. Table 8 provides the calculated burst pressures for each SG.

Table 8 95/50 Burst Pressures from W-Vol Cases for U-Bend Structural Support Wear Largest Max Projected U1R14 95/50 Beginning End of Flaw Growth Indication Projection Burst SG of Growth Growth (including EFPY Remaining EFPY Pressure Period Period NDE In-Service (psi)

Uncertainty)

(%TW)

(%TW) 1 R11 R14 4.03 21 7.1 49.6 4707 2 R11 R14 4.03 24 7.1 51.5 4577 3 R11 R14 4.03 27 7.1 61.3 3912 4 R11 R14 4.03 23 7.1 51.5 4500 In order to determine ATSG support structure wear growth rates, a data history review was performed by the lead eddy current analyst for each new ATSG wear indication measuring 20%TW or greater and a sampling of indications below this threshold. The purpose was to determine whether a measurable precursor signal was present but unreported in the prior inspection and to determine the associated growth rate for use on the OA projections. The growth rates are determined given an operating duration of 4.03 EFPY from U1R11 to U1R14 and normalizing to a %TW/EFPY basis. A summary of growth rates for the ATSG support structure wear indications in the SGs is summarized below in Table 9.

Table 9 ATSG Wear Growth Comparison Max. Standard Upper 95th Number of Avg Growth SG Indication Deviation Percentile Indications (%TW/EFPY)

(%TW) (%TW/EFPY) (%TW/EFPY) 1 74 33 2.10 1.53 4.62 2 139 37 1.95 1.47 4.37 3 83 26 2.45 1.84 5.48 4 123 34 2.61 1.88 5.70 The Westinghouse software W-VOL was utilized to support the license amendment for WBN Unit 1 permitting five cycles of operation between SG inspections (Reference 5). The W-VOL code applies a volume-based approach towards calculating wear over time. The method models a reduced volume removal rate over time due to less surface contact CNL-22-109 E27 of 32

Enclosure duration between the wear-initiating support structure and the tube. Therefore, this method can project a flaw growth that is based on the applicable work function that occurs with the mechanical wear experienced in the SGs, and thus removes excess conservativism when calculated using wear depth methods. Ultimately, this method can demonstrate an increased operational assessment interval in which the SG performance criteria is maintained for a flaw distribution set.

The WBN ATSG support structure wear flaws have been observed to be primarily tapered wear, as opposed to flat (or uniform depth) wear. To distinguish flat wear from tapered wear it is necessary to review terrain map graphics from rotating probe or non-rotating array probe inspections. In the volume-based approach the type of wear is important because at a given maximum depth flat wear will result in a greater volume of material that has worn away than tapered wear with the same maximum depth. It is conservative to assume that ATSG wear is flat wear. It is conservatively assumed that the ATSG wear is flat wear two inches wide. The initial runs of the W-VOL model only projected 5.4 EFPY of operation before burst pressure and probability of burst criteria would be exceeded. A review of the data showed that two wear indications that were left in service are the cause of the 5.4 EFPY limitation in the projection:

x SG2-R88C95-C03 with depth of 37%TW at U1R14 and 21%TW at U1R11 x SG4-R94C37-C03 with depth of 34%TW at U1R14 and 16%TW at U1R11 These indications are relatively deep and have relatively large growth rates for extended projections of operation. Eddy current graphics for both of these indications were reviewed and it was shown that both indications are tapered wear. Despite both flaws being very small in axial length, the bounding flaw length of two inches had been applied in the OA calculation, which resulted in 5.4 EFPY limitation. Review of array data from U1R14 shows that the flaw at SG2 R88C95 C03 is 0.31 inches long and the flaw at SG4 R94C37 C03 is 0.23 inches long. When these two indications are appropriately input as tapered wear, and it is conservatively assumed that the other ATSG wear is flat wear, the SG performance criteria is met for 5 cycles (7.1 EFPY) of operation using the volume-based W-VOL model.

The burst pressure results of the volume-based OA calculations are summarized below in Table 10.

Table 10 95/50 Burst Pressure from W-Vol Cases for Wear at ATSGs Largest Max Projected U1R14 95/50 Beginning End of Flaw Growth Indication Projection Burst SG of Growth Growth (including EFPY Remaining EFPY Pressure Period Period NDE In-Service (psi)

Uncertainty)

(%TW)

(%TW) 1 R11 R14 4.03 33 7.1 59.2 3972 2 R11 R14 4.03 37 7.1 59.4 4054 3 R11 R14 4.03 26 7.1 52.4 4419 4 R11 R14 4.03 34 7.1 56.7 3984 CNL-22-109 E28 of 32

Enclosure

9. The number and percentage of tubes plugged to date, and the effective plugging percentage in each SG (TS 5.9.9.e).

The percentage and effective percentage are the same for WBN Unit 1. Table 11 provides the numbers of tubes plugged for each degradation mechanism detected and the percentage of tubes currently plugged.

Table 11 Number of Tubes Plugged for Each Degradation Mechanism SG 1 SG 2 SG 3 SG 4 Total Plugged Tubes prior to U1R14 3 5 7 14 29 Plugged for U-bend Support Structure Wear 0 0 0 0 0 Plugged for Horizontal Grid Wear 0 0 0 0 0 Total Plugged to Date 3 5 7 14 29 Percentage Plugged to Date 0.06% 0.10% 0.14% 0.27% 0.14%

10. The results of any SG secondary-side inspection (TS 5.9.9.f). The number, type, and location (if available) of loose parts that could damage tubes removed or left in service in each SG.

A total of twelve foreign objects were discovered during U1R14 during foreign object search and retrieval (FOSAR). Six foreign objects were removed from the top of the tubesheet region, and six objects remain on the secondary side among the four SGs. The foreign objects remaining are small pieces of metal, wires, and bristles. Any foreign objects not able to be retrieved were characterized and an analysis performed to demonstrate acceptability of continued operation without exceeding the performance criteria.

Table 12 is a listing of the number of foreign objects discovered, retrieved, and removed.

Table 12 Foreign Objects Identified U1R14 SG Number Identified Number Retrieved Number Remaining 1 2 0 2 2 1 0 1 3 1 0 1 4 8 6 2 All 12 6 6 x SG1: Two foreign objects were identified in SG1 during the secondary side FOSAR inspection at the top-of-tubesheet (TTS). Retrieval attempts were made on both these objects but neither was able to be retrieved. The objects remaining are small with the largest being a 0.375 inch piece of either weld slag or hardened sludge.

x SG2: One foreign object was identified in SG2 during the secondary side FOSAR inspection at the TTS which was not retrieved. This object was a 0.375 inch long small diameter wire bristle fixed in the hardened sludge.

CNL-22-109 E29 of 32

Enclosure x SG3: One foreign object was identified in SG3 during the secondary side FOSAR inspection at the TTS which was not retrieved. This object was described as a 0.25 inch by 0.25 inch metallic tube remnant likely from a feedwater heater.

x SG4: Eight foreign objects were identified in SG4 during the secondary side FOSAR inspection at the TTS. Six of these objects were retrieved. The two objects remaining are small diameter wire bristles with the longest being 1.25 inches long.

An additional finding during the U1R14 FOSAR of SG4 was that an object, which was identified during U1R11 as an approximately 3.0 inch long weld wire, was no longer present. This object was previously located at tube row 24 between columns 20 and 21 and was not retrieved after multiple attempts during U1R11. It could not be conclusively determined that this object had been removed from the SG during U1R14 after searching the areas surrounding the last known location during FOSAR, reviewing the tubesheet sludge lance screens, and finding no associated loose part indications from the 100% eddy current inspection. The object was conservatively evaluated as though it remained in the SG secondary side following U1R14.

Table 13 is a listing of the largest items remaining in each SG with their locations.

Table 13 Largest Foreign Objects Left within each Steam Generator Estimated Object Dimensions (inch)

SG Description TTS Location Length Width Height 1 Weld Slag1 HL R41C66 0.375 0.170 0.125 2 Bristle HL R18C65 0.375 0.03 0.03 3 Tube Remnant CL R70C57 0.25 0.080 0.25 4 Bristle CL AN C9 1.25 0.005 0.005 4 Weld Wire Unknown2 3.0 0.05 0.05 TTS - Top-of-tubesheet, HL - Hot Leg, CL Cold Leg, AN - Annulus

1. Object is either weld slag or hardened sludge based on visual inspections but will conservatively be evaluated as weld slag.
2. Previously located at tube Row 24 between Columns 20 and 21 on the CL side but could not be re-located during U1R14
11. The scope, method, and results of secondary-side cleaning performed in each SG A TTS deposit/sludge removal process (i.e., sludge lancing) was performed in the four SGs during WBN U1R14. There are two purposes of the cleaning process. The first is to remove sludge and hardened deposits that preferentially form at the top of the tubesheet.

The second is to facilitate the discovery of any loose parts or foreign objects that have migrated to the SG secondary side during operation. The mass of deposit material and debris removed by the top of tubesheet cleaning process is summarized in Table 14.

CNL-22-109 E30 of 32

Enclosure Table 14 Top-of-Tubesheet Cleaning SG Quantity (lbs) 1 8.5 2 7.5 3 9.5 4 7.0 Total 32.5

12. The results of primary side component visual inspections performed in each SG Primary side inspections included visual inspections of the channel head bowl cladding and the divider plate. The installed tube plug inspections showed no conditions indicative of improper installation or in-service degradation. The visual inspections of the channel head bowl cladding and the divider plate showed no visually apparent evidence of degradation of the cladding, divider plate, or divider plate welds.

Visual inspections have been performed of the SG channel head bowl in the vicinity of the drain line in the SGs during U1R14. These inspections are performed based on industry operating experience and guideline requirements discussed in the degradation assessment.

Visual inspections of the SG hot leg and cold leg divider plate, inclusive of the entire divider plate-to-channel head weld and the visible clad surfaces, were performed in accordance with Westinghouse NSAL-12-1. This inspection was performed using the SG manway channel head bowl cameras. Satisfactory inspection results were observed in the SGs with no indications of cladding surface degradation.

13. Any plant specific reporting requirements, if applicable.

WBN Unit 1 TS 5.9.9 does not have any plant specific reporting requirements.

References

1. TVA letter to NRC, CNL-22-001, Application to Revise Technical Specifications to Adopt TSTF-577, Revised Frequencies for Steam Generator Tube Inspections (SQN-TS-21-03 and WBN-TS-21-08), dated April 4, 2022 (ML22095A023)
2. NRC letter to TVA, Sequoyah Nuclear Plant, Units 1 and 2; and Watts Bar Nuclear Plant, Units 1 and 2 - Issuance of Amendment Nos. 359, 353, 155, and 63 Regarding Adoption of Technical Specification Task Force Traveler TSTF-577, Revised Frequencies for Steam Generator Tube Inspections (EPID L-2022-LLA-0051), dated October 24, 2022 (ML22276A161)
3. TVA letter to NRC, Watts Bar Nuclear Plant (WBN) Unit 1 - Cycle 14 Steam Generator Tube lnspection Report, dated July 28, 2017 (ML17209A554)
4. Steam Generator Management Program: Steam Generator Integrity Assessment GuidelinesRevision 5. EPRI, Palo Alto, CA: 2021. 3002020909.

CNL-22-109 E31 of 32

Enclosure

5. TVA letter to NRC, CNL-20-078, Supplement to Application to Revise Watts Bar Nuclear Plant (WBN), Unit 1 Technical Specifications for Steam Generator Tube Inspection Frequency and to Adopt TSTF-510, Revision to Steam Generator Program Inspection Frequencies and Tube Sample Selection, (WBN-390-TS-20-012) (EPID L-2020-LLA-0161),

dated October 13, 2020 (ML20287A569)

6. NRC letter to TVA, Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment No. 147 Regarding Change to Steam Generator Tube Inspection Frequency and Adoption of Technical Specification Task Force (TSTF) Traveler TSTF-510 (EPID L-2020-LLA-0161),

dated July 26, 2021 (ML21153A049)

CNL-22-109 E32 of 32

Retrieved from "https://kanterella.com/w/index.php?title=CNL-22-109,_Steam_Generator_Tube_Inspection_Report_to_Reflect_TSTF-577_Reporting_Requirements&oldid=3524409"