NL-19-0204, R21 Steam Generator Tube Inspection Report

R21 Steam Generator Tube Inspection Report

ML19080A329
Person / Time
Site:	Vogtle
Issue date:	03/21/2019
From:	Gayheart C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-19-0204
Download: ML19080A329 (26)

Text

~ Southern Nuclear Cheryl A. Gayheart Regulatory Affairs Director 3535 Colonnade Parkway Birmingham, AL 35243 205 992 5316 tel 205 992 7601 fax cagayhea@ southernco.com MAR 2 1 2019 Docket No.: 50-424 NL-19-0204 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant- Unit 1 1R21 Steam Generator Tube Inspection Report Ladies and Gentlemen:

In accordance with the requirements of the Vogtle Electric Generating Plant Technical Specification 5.6.1 0, Southern Nuclear Operating Company submits the enclosed report of the steam generator tube inspections performed during the twenty-first refueling outage on Unit 1 (1 R21 ).

This letter contains no NRC commitments. If you have any questions, please contact Jamie Coleman at 205.992.6611.

Cheryl . ayheart Regulatory Affairs Director CAG/kgl/sm

Enclosure:

1 R21 Steam Generator Tube Inspection Report Cc: Regional Administrator NRR Project Manager- Vogtle 1 & 2 Senior Resident Inspector- Vogtle 1 & 2 RType: CVC7000

Vogtle Electric Generating Plant - Unit 1 1R21 Steam Generator Tube Inspection Report Enclosure 1R21 Steam Generator Tube Inspection Report

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report Introduction The Vogtle Electric Generating Plant (VEGP) twenty-first refueling outage on Unit 1 (1 R21) outage was conducted after Steam Generator (SG) service equivalent to 1.43 effective full power years (EFPY) from previous SG eddy current inspections. During this operational interval, no tube leakage was reported. Approximately 40.72 effective full power months (EFPM) of the 72 EFPM in the fourth sequential period have been accrued at Vogtle 1R21. VEGP 1R21 is the third inspection of the period. Analysis based on conservative assumptions used in the Condition Monitoring (CM) and Operational Assessments (OA), demonstrated that there were no tubes that exceeded the Reg. Guide 1.121 or NEI-97-06 Revision 3 criteria for tube integrity during Cycle 21.

The eddy current inspections were performed by the Steam Generator Maintenance Services Group of the Westinghouse Nuclear Services Division. Secondary data analysis was performed by NDE Technology under direct contract with Southern Nuclear Operating Company (SNC).

During VEGP 1R21, a total of three tubes were plugged. None of the indications exceeded the condition monitoring limits identified in the Degradation Assessment and therefore did not require in-situ pressure testing. Permanent H* Alternate Repair Criteria (ARC) has been approved for implementation by the NRC. Therefore, SNC and Westinghouse omitted tube end

+Point' inspections below top of tubesheet (TIS) -15.2 inches. TIS inspections ranged from TIS +3 inches to TIS -15.2 inches. The scope and results of inspections on each SG, are described below.

Voqtle 1R21 SG Scope The scope for 1R21 involved the scheduled inspections listed below. In accordance with the EPRI PWR SG Examination Guidelines, Revision 8, the 1R21 program addressed Vogtle 1 degradation mechanisms observed from prior inspections as well as those regarded as potential degradation mechanisms. In-service inspection (lSI) examination used Bobbin and Rotating Pancake Coil (RPC) +Point' Eddy Current Testing (ECT) inspection methods. Scope during 1R21 included:

• Bobbin examination of tubes with previously detected indications of degradation.

• 50% +POINT' probe examination of hot leg (HL) tubes in SGs 1/2/3 and 100% in SG4 from the top of the tubesheet (TIS) to the licensed ARC depth for H* (TSH +3/-15.2 inches). This inspection satisfies the required periodic sample that accompanies regulatory approval of H*.

• 50% +POINT of the HL tube bulge (BLG) and overexpansion (OXP) populations in all four SGs. This scope was captured as part of the HL tubesheet inspection scope.

Scope expanded to 100% in SG4 in course of the tubesheet program scope expansion.

The BLG and OXP indications are defined as follows:

BLG = differential mix diameter discontinuity signal within the tubesheet of 18 volts or greater as measured by bobbin coil probe.

OXP = a tube diameter deviation within the tubesheet of 1.5 mils or greater as measured by bobbin coil profile analysis.

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Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report

• +POINT probe examination of the HL and cold leg (CL) periphery and tubelane, excluding tubelane Columns 12 through 111, three tubes deep from TTS +3/-15.2 inches on the HL side and TTS +3/-3 inches on the CL side in all SGs.

• 50% +POINT probe examination of Row 1 and Row 2 U-bends from the top TSP on the HL side to the top TSP on the CL side in all SGs.

Scope expanded to 100% in all SGs upon discovery of Row 1 axial primary water stress corrosion cracking (PWSCC) indication in SG2.

• +POINT probe examination of Special Interest of bobbin possible flaw locations including U-bends in both the HL and CL.

• All secondary side foreign objects identified and any existing possible loose part (PLP) indications from the most recent inspection were 'boxed-in' by at least one tube with

+POINT probe. Newly reported PLPs or foreign object wear indications were 'boxed-in' by at least two tubes with +POINT probe inspection.

• 25% +POINT probe examination of dents and dings 2:2 volts in HL straight lengths and U-bends of all SGs. This sample was taken from the total number of dents and dings identified during previous inspections and any additional identified by the bobbin program.

• 100% +POINT probe examination of all HL and CL TSP intersections, HL and CL TTS expansion transitions and all dents and dings 2: 2 volts of 2-sigma high stress tubes in all SGs.

• 100% visual inspection of all installed tube plugs from the primary side in all SGs.

• 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. The known anomaly in the CL channel head of SG1, previously dispositioned, was evaluated for a change from the analyzed condition during this inspection.

Secondary Side activities performed included:

• TTS Sludge Lancing in all SGs

• Foreign Object Search and Retrieval (FOSAR) in all SGs Inspection Expansion Vogtle 1R21 SG in-service inspections (lSI) required non-destructive examination (NDE) inspection scope expansion for the low row U-bend +Point probe inspections to be increased from 50% to 100% of the Row 1 and Row 2 U-bend regions in all SGs. Scope expansion was due to detecting an indication of axial PWSCC in a Row 1 U-bend in SG2.

Damage Mechanisms Found and NDE Techniques Utilized Many of the damage mechanisms found during 1R21 inspections were identified in previous inspections and in the 1R21 SG Degradation Assessment. The only new damage mechanism E-2

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report discovered on Unit 1 was mechanical wear at tube support plate. The damage mechanisms are listed below with the associated inspection method:

• Mechanical wear due to a foreign object was found in all SGs. +Point and bobbin techniques were used to evaluate the wear.

• Mechanical wear at anti-vibration bars (AVBs) were found in all SGs. Bobbin technique was used to evaluate the wear.

• Mechanical wear and wall loss from secondary side cleaning processes found in all SGs.

+ Point techniques was used to evaluate the wear.

• Mechanical wear at tube support plate was found in SGs 1 and 4. +Point and bobbin techniques were used to evaluate the wear.

• ODSCC at the hot leg expansion transitions were found in SG 4. + Point techniques was used to evaluate the wear.

• PWSCC in the small radius U-Bends was found in SG 2. + Point techniques was used to evaluate the wear.

Service Induced Indication Descriptions Mechanical Wear due to Foreign Objects Foreign objects have been previously reported as the cause for tube wear at Vogtle Unit 1 during prior inspections. Therefore, wear due to foreign objects is classified as an existing degradation mechanism and has been addressed in the SG inspections performed during Vogtle 1R21.

Table 1, Possible Loose Part (PLP) Indications, lists the data record for the eddy current signals corresponding to a PLP. Previous historical PLP indications listed showed no significant change in eddy current signal response. There were 9 newly reported PLP signals in 2R21. Two of the newly reported PLP indications within SG4 were identified as a metallic object that was removed from the SG. No evidence of tube wear associated with these PLP signals was detected visually or through eddy current testing.

Table 2 lists tube wear indications attributable to loose parts and foreign objects in 1R21. The foreign object wear indications with percent through-wall (PCT) identified show no apparent growth or change outside of measurement uncertainties. There was 1 newly reported volumetric indication in 1R21 which measured at a depth of 9% TW. This indication was found in SG 2 at R53 C48 on top of TSC. There was no evidence of a loose part associated with this indication at this tube or surrounding tubes detected using eddy current testing.

In 1R21, the largest volumetric wear flaw was measured at 32% TW. The through-wall depth is less than the volumetric wear condition monitoring limit of 48% TW at 3~PNo. For pressure-only loading of volumetric flaws, structural integrity implies meeting leakage integrity at accident conditions since the steam line break accident condition pressure differential is much smaller E-3

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report than 3flPNo. Based on the inspection data, 1R21 condition monitoring (CM) has been met for degradation associated with foreign object wear indications.

Table 1: Vogtle 1R21 Possible Loose Part Indications (PLP)

SG Row Column Indication Location 1 25 8 PLP TSH + 0.55 1 25 9 PLP TSH +0.56 1 38 73 PLP TSH +0.15 1 28 77 PLP TSH +0.12 1 29 77 PLP TSH+0.17 1 29 78 PLP TSH +0.21 1 3 79 PLP TSC +0.08 1 32 85 PLP TSH +0.07 1 36 87 PLP TSH +0.07 1 36 88 PLP TSH +0.11 1 20 90 PLP TSH +0.19 1 14 112 PLP TSH +1.55 1 15 112 PLP TSH +1.59 2 18 8 PLP TSH +0.9 2 19 8 PLP TSH +0.75 2 50 35 PLP TSH +0.4 2 51 35 PLP TSH +0.46 2 35 106 PLP TSH +0.2 2 36 106 PLP TSH +0.18 4 30 18 PLP TSH +1.49 4 31 18 PLP TSH +1.69 4 8 107 PLP TSH +0.14 4 14 119 PLP TSC +0.15 4 14 120 PLP TSC +0.16 TSH- Tubesheet reg1on on HL side TSC-Tubesheet region on CL side E-4

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report Table 2: Vogtle 1R21 Foreign Object Wear Indications (PCT)

SG Row Column Indication Percent 1 Location 1 24 66 PCT 7 3C +24.97 1 55 82 PCT 24 BPH +0.48 1 56 82 PCT 3 BPH +0.64 1 41 97 PCT 22 TSC +0.09 1 39 100 PCT 13 TSH +0.3 1 41 100 PCT 15 TSH +0.24 1 41 100 PCT 32 TSH +0.14 1 41 101 PCT 24 TSH +0.19 1 41 102 PCT 21 TSH +0.17 1 41 103 PCT 22 TSH +0.49 2 6 1 PCT 6 1C +1.25 2 54 46 PCT 14 TSC +0.08 2 53 48 PCT 9 TSC +0.34 3 29 111 PCT 12 BPH -0.13 3 30 111 PCT 32 BPH +0.78 4 40 57 PCT 9 6H +13.11 4 49 89 PCT 9 BPH +0.37 4 38 104 PCT 12 BPH +0.15 1

lndicates the tube percent through wall depth measured by a qualified bobbin or +Point technique.

TSH- Tubesheet region on HL side lC- Tube Support Plate 1 on CL side TSC-Tubesheet region on CL side 6H- Tube Support Plate 6 on HL side 3C- Tube Support Plate 3 on CL side BPH- Baffle Plate on HL side Mechanical Wear at Anti-Vibration Bar (AVB) Supports The complete listing of AVB wear locations and eddy current signals is provided in Table 3 through 6. All AVB wear locations in each SG have been examined; there were no wear locations which exceeded the Technical Specification plugging limit of 40% through-wall (TW).

Stabilizer installation was not required for plugging.

During 1R21, the maximum AVB wear indication reported was 38% TW which occurred at two locations; SG1 at R41C44 AV3 and SG2 at R39C103 AV5. The largest depth AVB wear indication of 38% TW satisfies the 64% TW condition monitoring limit at 3~PNo. CM has been met at the 1R21 inspection for degradation associated with AVB wear.

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Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report Table 3: Vogtle 1R21 SG1 AVB Wear Indications SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 1 23 40 9 AV6 1 39 48 25 AV3 1 23 116 12 AV6 1 39 48 24 AV4 1 24 116 13 AV2 1 39 48 17 AV5 1 24 116 15 AV5 1 39 87 9 AV4 1 26 115 14 AV2 1 39 90 9 AV2 1 26 115 10 AV5 1 39 90 12 AV3 1 26 116 15 AV1 1 39 95 10 AV3 1 26 116 24 AV6 1 39 104 11 AV4 1 27 100 10 AV5 1 40 20 14 AV4 1 27 115 10 AV1 1 40 34 9 AV2 1 27 115 12 AV6 1 40 34 10 AV3 1 28 114 9 AV2 1 40 34 16 AV4 1 28 115 16 AV1 1 40 34 8 AV6 1 28 115 26 AV6 1 40 38 13 AV3 1 32 104 10 AV6 1 40 38 15 AV4 1 34 107 11 AV1 1 40 47 31 AV3 1 34 107 15 AV3 1 40 47 34 AV4 1 35 16 15 AV4 1 40 47 10 AV5 1 35 18 12 AV6 1 40 47 12 AV6 1 35 34 7 AV3 1 40 62 19 AV3 1 35 34 7 AV4 1 40 62 11 AV4 1 35 104 12 AV3 1 40 62 10 AV5 1 35 104 9 AV4 1 40 75 10 AV3 1 36 49 8 AV3 1 40 94 10 AV4 1 36 105 13 AV3 1 40 104 16 AV3 1 37 77 15 AV3 1 40 104 16 AV4 1 37 77 13 AV6 1 41 18 12 AV4 1 37 100 13 AV5 1 41 18 10 AV5 1 37 102 23 AV5 1 41 18 17 AV6 1 38 16 18 AV1 1 41 23 15 AV3 1 38 16 20 AV2 1 41 23 12 AV4 1 38 16 17 AV3 1 41 34 7 AV4 1 38 16 31 AV4 1 41 44 25 AV2 1 38 16 11 AV5 1 41 44 38 AV3 1 38 16 10 AV6 1 41 51 8 AV2 1 38 62 11 AV4 1 41 51 11 AV4 1 38 108 8 AV1 1 41 80 11 AV3 E-6

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 1 38 108 10 AV6 1 41 96 10 AV4 1 39 48 16 AV2 1 41 96 10 AV6 1 42 34 15 AV4 1 45 30 13 AVS 1 42 37 12 AV6 1 45 36 11 AVS 1 42 43 11 AV2 1 45 90 17 AV2 1 42 43 11 AV3 1 45 90 10 AV3 1 42 43 13 AV4 1 46 41 5 AV1 1 42 43 14 AVS 1 46 75 11 AV6 1 42 47 9 AV6 1 47 99 11 AV2 1 42 97 13 AV3 1 48 97 13 AVl 1 42 97 12 AV4 1 49 28 19 AV4 1 43 21 9 AV2 1 49 28 23 AVS 1 43 21 10 AV3 1 49 88 9 AV4 1 43 21 30 AV4 1 so 29 13 AVl 1 43 21 33 AVS 1 so 29 10 AV2 1 43 21 10 AV6 1 51 45 10 AV6 1 43 75 11 AV6 1 52 33 20 AV2 1 43 78 16 AVS 1 52 33 20 AV3 1 43 81 13 AV4 1 52 39 22 AV2 1 43 81 10 AVS 1 52 39 29 AV3 1 43 82 16 AV3 1 52 39 30 AV4 1 43 83 9 AVl 1 52 39 12 AVS 1 43 83 19 AV2 1 52 44 22 AV4 1 43 83 19 AV3 1 52 44 11 AVS 1 43 83 20 AV4 1 52 91 13 AV1 1 43 83 12 AVS 1 53 39 11 AV6 1 43 85 14 AV2 1 53 43 7 AV2 1 43 91 32 AV2 1 53 43 8 AVS 1 43 91 18 AV3 1 53 43 11 AV6 1 43 91 15 AV4 1 53 87 10 AV3 1 44 21 15 AV3 1 53 90 11 AV3 1 44 21 17 AV4 1 53 90 13 AV6 1 44 21 19 AVS 1 54 36 13 AV2 1 44 75 11 AV6 1 54 37 15 AVl 1 44 80 8 AV3 1 54 37 11 AVS 1 44 80 13 AV4 1 54 37 13 AV6 1 44 80 9 AVS 1 54 45 9 AV2 1 44 102 11 AV2 1 54 53 12 AV2 1 45 26 13 AV3 1 54 53 10 AV3 E-7

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 1 45 26 11 AV5 1 54 83 10 AVl 1 45 30 15 AV3 1 54 83 11 AV6 1 57 45 21 AV2 1 58 49 13 AV5 1 57 45 36 AV3 1 58 49 13 AV6 1 57 45 11 AV5 1 58 51 13 AV6 1 57 45 14 AV6 1 58 75 13 AVl 1 57 47 9 AV3 1 58 76 10 AV6 1 57 47 9 AV5 1 59 62 12 AV6 E-8

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report Table 4: Vogtle 1R21 SG2 AVB Wear Indications SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 2 26 49 11 AV2 2 38 89 13 AV2 2 27 115 9 AV2 2 38 89 13 AV3 2 27 115 9 AV5 2 38 89 14 AV4 2 28 12 8 AV2 2 38 89 17 AV5 2 28 112 12 AV2 2 38 89 11 AV6 2 28 112 12 AV6 2 38 99 7 AV3 2 30 110 11 AV2 2 38 105 10 AV5 2 32 12 6 AV1 2 38 106 28 AV5 2 32 12 20 AV3 2 38 107 12 AV3 2 32 37 8 AV6 2 38 107 11 AV6 2 33 74 13 AV3 2 38 108 9 AV3 2 34 106 14 AV3 2 38 108 11 AV4 2 34 108 16 AV4 2 39 18 12 AV4 2 35 13 12 AV3 2 39 20 11 AV3 2 35 13 13 AV4 2 39 38 21 AV2 2 35 13 12 AV5 2 39 100 8 AV5 2 35 13 10 AV6 2 39 103 38 AV5 2 35 14 14 AV3 2 39 105 15 AV2 2 35 14 12 AV5 2 39 105 14 AV3 2 35 17 12 AV3 2 39 105 23 AV5 2 35 18 9 AV6 2 40 22 11 AV3 2 35 25 10 AV3 2 40 22 10 AV4 2 35 32 11 AV4 2 40 30 8 AV4 2 35 32 10 AV6 2 40 37 17 AV4 2 35 83 15 AV3 2 40 39 13 AV4 2 35 83 9 AV4 2 40 41 13 AV2 2 35 83 21 AV5 2 40 41 15 AV3 2 35 83 15 AV6 2 40 41 14 AV4 2 35 100 8 AV5 2 40 93 19 AV2 2 35 101 11 AV5 2 40 93 13 AV3 2 35 104 14 AV3 2 40 93 23 AV5 2 35 105 16 AV5 2 40 95 7 AV3 2 35 105 13 AV6 2 40 98 23 AV5 2 36 13 6 AV3 2 40 105 13 AV2 2 36 42 10 AV2 2 40 105 10 AV3 2 36 42 10 AV4 2 40 105 23 AV5 2 36 108 9 AV6 2 41 33 25 AV4 2 37 34 9 AV2 2 41 33 21 AV5 E-9

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 2 37 97 12 AV3 2 41 39 11 AV3 2 41 39 16 AV4 2 42 97 35 AV4 2 41 42 18 AV2 2 42 97 11 AVS 2 41 42 10 AV3 2 42 100 17 AV3 2 41 42 29 AV4 2 42 100 20 AV4 2 41 42 34 AVS 2 42 101 9 AV2 2 41 100 9 AV3 2 42 101 16 AV4 2 41 100 14 AVS 2 42 101 14 AVS 2 41 103 21 AVS 2 43 63 19 AV4 2 42 56 8 AV2 2 43 68 13 AV3 2 42 66 15 AV3 2 43 68 14 AVS 2 42 72 17 AV2 2 43 81 10 AVS 2 42 72 18 AV3 2 43 84 13 AV3 2 42 72 10 AVS 2 43 84 14 AVS 2 42 76 7 AV1 2 43 87 17 AV2 2 42 76 28 AV2 2 43 87 19 AV3 2 42 76 19 AV3 2 43 87 12 AV4 2 42 76 19 AV4 2 43 87 25 AVS 2 42 76 36 AVS 2 43 88 13 AV2 2 42 76 19 AV6 2 43 88 20 AV3 2 42 84 12 AV3 2 43 88 20 AVS 2 42 84 8 AV4 2 43 91 31 AV2 2 42 84 13 AVS 2 43 91 21 AV3 2 42 86 14 AV3 2 43 91 13 AV4 2 42 87 9 AV2 2 43 91 31 AVS 2 42 88 17 AV4 2 43 91 15 AV6 2 42 91 10 AV2 2 43 93 17 AV2 2 42 91 17 AV4 2 43 93 24 AV3 2 42 92 15 AV4 2 43 93 23 AV4 2 42 92 13 AVS 2 43 93 16 AVS 2 42 94 18 AV3 2 43 94 12 AV2 2 42 94 24 AV4 2 43 94 13 AV3 2 42 94 12 AVS 2 43 94 11 AV4 2 42 95 10 AV2 2 43 95 17 AV4 2 42 96 12 AV2 2 43 95 16 AVS 2 42 96 12 AV3 2 43 95 12 AV6 2 42 96 16 AV4 2 43 96 11 AV3 2 42 96 14 AVS 2 43 96 15 AVS 2 42 97 11 AV2 2 44 96 8 AVS E-10

Enclosure to NL-19-0204 1 R21 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 2 42 97 22 AV3 2 44 100 8 AV4 2 45 94 11 AV3 2 so 92 14 AV2 2 46 49 10 AV2 2 so 92 19 AV3 2 46 49 25 AV3 2 so 92 10 AV4 2 46 49 18 AV4 2 51 81 12 AV2 2 46 so 24 AV1 2 51 81 12 AV4 2 46 so 34 AV2 2 52 79 10 AV4 2 46 so 33 AV3 2 52 91 21 AV2 2 46 so 31 AV4 2 52 91 14 AVS 2 46 so 25 AVS 2 53 61 12 AVS 2 46 so 12 AV6 2 53 79 18 AV2 2 46 53 12 AVS 2 53 79 23 AV3 2 46 53 10 AV6 2 53 87 14 AV5 2 46 58 27 AV2 2 54 36 8 AV2 2 46 58 10 AV3 2 54 75 10 AVS 2 46 58 12 AV4 2 54 84 8 AV2 2 46 58 15 AVS 2 54 84 23 AV3 2 46 94 12 AV4 2 54 84 20 AV4 2 46 96 14 AV2 2 54 84 30 AVS 2 46 98 14 AVS 2 54 84 12 AV6 2 47 90 8 AV3 2 55 83 21 AV5 2 48 86 13 AV4 2 55 84 25 AVS 2 48 86 10 AVS 2 56 72 13 AV2 2 48 98 11 AV3 2 56 72 14 AV3 2 48 98 17 AV4 2 57 72 8 AV1 2 48 98 21 AVS 2 57 79 14 AV4 2 48 98 25 AV6 2 57 79 16 AVS 2 49 89 12 AV3 2 so 89 37 AV4 2 49 89 22 AV4 2 49 89 23 AVS 2 49 91 9 AVS 2 50 83 12 AV2 2 so 83 10 AV3 2 50 84 11 AV2 2 so 84 30 AV3 2 50 84 33 AV4 2 50 84 13 AVS 2 so 89 20 AV2 2 50 89 18 AV3 E-11

Enclosure to NL-19-0204 1 R21 Steam Generator Tube Inspection Report Table 5: Vogtle 1 R21 SG3 AVB Wear Indications SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 3 20 55 9 AV2 3 39 17 9 AV5 3 25 115 7 AV2 3 39 17 27 AV6 3 25 115 10 AV5 3 39 20 11 AV4 3 28 8 16 AV1 3 39 21 11 AV2 3 28 8 21 AV6 3 39 21 12 AV5 3 28 51 8 AV5 3 39 26 32 AV2 3 32 52 6 AV1 3 39 26 13 AV5 3 34 110 9 AV4 3 39 29 17 AV2 3 35 16 11 AV1 3 39 32 9 AV3 3 35 16 17 AV3 3 39 35 12 AV2 3 35 16 12 AV4 3 39 35 27 AV3 3 35 16 11 AV5 3 39 35 20 AV4 3 36 13 11 AV5 3 39 35 13 AV5 3 36 29 7 AV2 3 39 48 6 AV4 3 36 34 9 AV2 3 39 51 11 AV3 3 36 34 11 AV5 3 39 57 7 AV2 3 36 34 10 AV6 3 39 62 7 AV4 3 36 44 8 AV2 3 39 63 17 AV3 3 36 44 10 AV5 3 39 63 9 AV5 3 37 106 8 AV6 3 39 66 16 AV3 3 37 107 17 AV1 3 39 66 11 AV4 3 37 107 13 AV4 3 39 66 16 AV5 3 37 107 13 AV5 3 39 67 14 AV3 3 37 108 10 AV1 3 39 67 15 AV4 3 37 108 10 AV2 3 39 82 10 AV5 3 37 108 12 AV6 3 39 102 17 AV2 3 38 17 12 AV6 3 39 102 24 AV5 3 38 34 9 AV2 3 40 18 8 AV3 3 38 34 11 AV4 3 40 18 9 AV4 3 38 34 8 AV5 3 40 18 10 AV6 3 38 35 11 AV5 3 40 19 9 AV1 3 38 69 10 AV3 3 40 19 15 AV2 3 38 106 16 AV3 3 40 19 10 AV4 3 38 106 10 AV5 3 40 19 19 AV5 3 38 106 16 AV6 3 40 19 13 AV6 3 38 107 15 AV4 3 40 30 23 AV5 3 39 17 11 AV2 3 40 30 11 AV6 3 39 17 26 AV3 3 40 35 11 AV4 E-12

Enclosure to NL-19-0204 1 R21 Steam Generator Tube Inspection Report SG Row Column  % TWD 1 Location 2 SG Row Column %TWD 1 Location 3 39 17 21 AV4 3 40 38 9 AV6 3 40 41 10 AV3 3 41 102 10 AV6 3 40 91 13 AV3 3 41 103 14 AVS 3 40 96 10 AV3 3 41 103 12 AV6 3 40 97 17 AV3 3 42 21 15 AV2 3 40 97 15 AV4 3 42 21 15 AV3 3 40 98 16 AV2 3 42 21 16 AV4 3 40 98 8 AV3 3 42 21 17 AVS 3 40 98 10 AV4 3 42 22 11 AV2 3 40 100 17 AV2 3 42 22 9 AV4 3 40 100 10 AV4 3 42 22 10 AVS 3 40 100 12 AVS 3 42 22 11 AV6 3 40 101 13 AV2 3 42 23 7 AV2 3 40 101 12 AVS 3 42 23 10 AV3 3 40 102 24 AV2 3 42 23 29 AV4 3 40 102 12 AV6 3 42 23 14 AVS 3 40 104 11 AV2 3 42 25 12 AV4 3 40 104 20 AV4 3 42 25 8 AVS 3 40 104 11 AVS 3 42 26 17 AV4 3 40 104 15 AV6 3 42 26 18 AVS 3 40 105 14 AV6 3 42 27 14 AV2 3 40 106 15 AV6 3 42 27 11 AV4 3 41 19 12 AV3 3 42 27 25 AVS 3 41 19 17 AV4 3 42 28 12 AV2 3 41 19 29 AVS 3 42 28 9 AV3 3 41 19 11 AV6 3 42 28 10 AV4 3 41 20 16 AV4 3 42 28 9 AVS 3 41 20 15 AVS 3 42 28 10 AV6 3 41 21 17 AV4 3 42 29 9 AV3 3 41 21 14 AVS 3 42 29 14 AV4 3 41 24 10 AV3 3 42 29 9 AVS 3 41 89 13 AVS 3 42 35 26 AV4 3 41 99 14 AV3 3 42 35 18 AVS 3 41 99 29 AVS 3 42 38 9 AV6 3 41 100 11 AV2 3 42 43 15 AV2 3 41 100 10 AV4 3 42 43 13 AVS 3 41 102 23 AV2 3 42 43 6 AV6 3 41 102 32 AV3 3 42 48 9 AV3 3 41 102 29 AV4 3 42 50 6 AV1 E-13

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 3 41 102 13 AVS 3 42 so 27 AV2 3 42 so 16 AV3 3 45 69 12 AV2 3 42 so 34 AV4 3 45 69 10 AV3 3 42 so 8 AVS 3 45 69 17 AVS 3 42 58 11 AV2 3 45 77 14 AV2 3 42 58 19 AV3 3 45 77 11 AV3 3 42 63 23 AV4 3 45 77 9 AV4 3 42 66 12 AV3 3 45 82 23 AV3 3 42 66 17 AV4 3 45 82 18 AV4 3 42 67 12 AV3 3 45 100 12 AVS 3 42 67 11 AVS 3 46 24 11 AV4 3 42 102 11 AV4 3 46 25 7 AV3 3 42 102 11 AV6 3 46 25 11 AV4 3 44 22 9 AV3 3 46 25 14 AVS 3 44 22 9 AV4 3 46 25 10 AV6 3 44 22 14 AVS 3 47 26 16 AVS 3 44 26 31 AV2 3 47 30 11 AVS 3 44 102 9 AV4 3 47 35 9 AV2 3 45 22 12 AVS 3 47 35 13 AV4 3 45 40 18 AV3 3 47 38 18 AV2 3 45 40 13 AV4 3 47 38 28 AV4 3 45 40 16 AVS 3 47 38 10 AVS 3 45 40 9 AV6 3 47 45 9 AV2 3 45 46 12 AV1 3 47 45 20 AV4 3 45 46 35 AV2 3 47 56 11 AV3 3 45 46 34 AV3 3 47 95 9 AV6 3 45 46 23 AV4 3 47 96 25 AV4 3 45 46 19 AVS 3 48 25 9 AV6 3 45 48 17 AV2 3 48 27 8 AV2 3 45 48 26 AV3 3 49 34 28 AV4 3 45 48 18 AVS 3 49 34 13 AVS 3 45 48 7 AV6 3 49 92 10 AV4 3 45 49 27 AV2 3 49 92 13 AVS 3 45 49 30 AV3 3 49 93 11 AV6 3 45 61 13 AV3 3 49 96 12 AV4 3 45 61 18 AV4 3 49 96 14 AVS 3 45 61 21 AVS 3 49 96 31 AV6 3 45 64 22 AV3 3 so 33 10 AV3 3 45 67 22 AV3 3 so 33 11 AV4 E-14

Enclosure to NL-19-0204 1 R21 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 3 45 67 24 AV4 3 50 33 10 AV5 3 50 83 17 AV5 3 53 84 13 AV5 3 50 86 13 AV2 3 54 88 9 AV1 3 50 86 9 AV3 3 54 88 9 AV6 3 50 86 16 AV5 3 57 53 11 AV6 3 51 55 11 AV3 3 58 52 15 AV6 3 51 55 13 AV4 3 58 61 10 AV1 3 51 55 9 AV5 3 59 61 14 AV4 3 51 92 12 AV6 3 59 63 14 AV6 3 53 84 20 AV3 3 59 68 15 AV6 3 53 84 31 AV4 E-15

Enclosure to NL-19-0204 1 R21 Steam Generator Tube Inspection Report Table 6: Vogtle 1 R21 SG4 AVB Wear Indications SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 4 27 8 16 AV6 4 33 111 19 AV3 4 27 9 20 AV5 4 33 111 22 AV4 4 27 43 9 AV5 4 33 111 18 AV6 4 27 51 12 AV2 4 34 15 8 AV5 4 28 40 18 AV5 4 36 13 8 AVl 4 28 65 10 AV5 4 36 13 8 AV2 4 28 82 10 AV2 4 36 14 8 AVl 4 28 82 11 AV5 4 36 39 21 AV3 4 30 9 19 AV2 4 36 79 15 AV4 4 30 9 36 AV5 4 36 104 14 AV2 4 30 9 6 AVG 4 36 104 10 AV3 4 30 20 9 AV2 4 36 104 10 AV5 4 30 40 12 AV2 4 36 105 9 AV2 4 30 40 16 AV5 4 36 105 12 AV5 4 30 40 9 AV6 4 36 106 8 AV5 4 30 85 9 AV2 4 36 106 9 AV6 4

• 30 113 10 AV5 4 36 107 10 AV3 4 30 114 31 AV5 4 36 109 10 AV3 4 31 111 8 AV1 4 37 80 6 AV4 4 31 111 11 AV2 4 37 107 15 AV3 4 32 106 12 AV3 4 37 107 12 AV5 4 32 107 10 AV2 4 38 19 8 AV5 4 32 110 11 AV3 4 38 35 9 AV2 4 32 111 9 AV1 4 38 52 9 AV3 4 32 111 14 AV3 4 38 52 12 AV4 4 32 111 9 AV4 4 38 55 9 AV4 4 33 12 13 AV2 4 38 74 9 AV2 4 33 12 11 AV3 4 38 76 14 AV3 4 33 12 6 AV4 4 38 76 16 AV4 4 33 12 11 AV6 4 38 76 8 AV6 4 33 34 11 AV3 4 38 86 15 AV4 4 33 34 11 AV4 4 38 96 15 AV2 4 33 34 11 AV5 4 38 96 7 AV4 4 33 91 7 AV2 4 38 96 9 AV5 4 33 91 10 AV4 4 38 103 12 AV4 4 33 108 12 AV3 4 38 103 10 AV5 4 33 110 21 AV3 4 38 104 11 AV3 4 33 110 12 AV5 4 38 104 22 AV4 E-16

Enclosure to NL-19-0204 1 R21 Steam Generator Tube Inspection Report SG Row Column  % TWD 1 Location 2 SG Row Column %TWD 1 Location 4 33 110 8 AV6 4 38 104 14 AV5 4 38 108 14 AV4 4 40 87 15 AV4 4 39 37 11 AV2 4 40 87 17 AV5 4 39 37 11 AV3 4 40 88 14 AV3 4 39 51 13 AV4 4 40 88 19 AV4 4 39 51 11 AV5 4 40 88 14 AV5 4 39 51 15 AV6 4 40 88 12 AV6 4 39 56 12 AV2 4 40 90 7 AV3 4 39 56 17 AV3 4 40 90 14 AV4 4 39 56 14 AV4 4 40 90 8 AV5 4 39 58 10 AV2 4 40 92 9 AV3 4 39 58 23 AV4 4 40 92 13 AV5 4 39 58 13 AV6 4 40 93 17 AV2 4 39 75 16 AV5 4 40 93 12 AV5 4 39 78 10 AV5 4 40 95 12 AV2 4 39 95 10 AV2 4 40 95 12 AV3 4 39 95 11 AV4 4 40 95 25 AV4 4 39 107 11 AV3 4 40 95 12 AVS 4 40 24 13 AVS 4 40 100 14 AV2 4 40 25 10 AV3 4 40 100 8 AV3 4 40 29 11 AV2 4 40 100 11 AV4 4 40 39 16 AV3 4 40 100 9 AVS 4 40 56 16 AV3 4 40 100 11 AV6 4 40 62 26 AV2 4 40 105 9 AV2 4 40 62 35 AV3 4 40 105 19 AV4 4 40 62 28 AV4 4 40 105 20 AVS 4 40 62 12 AVS 4 40 106 12 AV2 4 40 78 18 AV2 4 40 106 22 AV3 4 40 78 16 AV3 4 40 106 18 AV4 4 40 78 9 AVS 4 40 106 29 AVS 4 40 80 10 AV3 4 41 23 10 AV2 4 40 80 10 AVS 4 41 97 15 AVS 4 40 82 11 AV2 4 41 99 14 AVS 4 40 82 23 AV3 4 41 105 9 AV3 4 40 82 36 AV4 4 42 20 10 AV6 4 40 82 19 AVS 4 42 100 18 AV2 4 40 84 16 AV2 4 42 100 15 AV3 4 40 84 9 AV5 4 42 100 18 AV4 4 40 86 12 AV4 4 42 100 11 AV5 E-17

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 4 40 86 9 AVS 4 42 100 11 AV6 4 42 101 17 AV3 4 so 76 15 AV4 4 42 101 24 AV4 4 so 76 29 AVS 4 42 101 29 AVS 4 53 89 12 AV4 4 42 104 10 AV1 4 53 90 9 AV1 4 42 104 17 AV3 4 53 90 11 AVS 4 42 104 11 AV4 4 53 90 11 AV6 4 43 46 20 AV6 4 54 36 12 AVS 4 43 66 14 AV2 4 54 38 8 AV1 4 43 66 13 AV3 4 54 38 10 AVS 4 43 85 12 AV2 4 54 38 8 AV6 4 43 92 15 AV3 4 54 87 9 AV2 4 43 93 11 AV4 4 54 87 10 AV3 4 43 101 14 AV3 4 54 87 12 AV4 4 43 101 15 AV4 4 55 40 10 AV6 4 43 101 27 AVS 4 55 82 10 AV4 4 44 91 15 AVS 4 55 82 11 AVS 4 44 96 8 AV2 4 56 41 10 AVS 4 44 96 31 AV3 4 56 81 11 AV6 4 44 96 23 AV4 4 57 55 10 AV6 4 44 96 14 AV6 4 58 48 9 AVS 4 44 97 24 AV2 4 58 65 10 AV1 4 44 97 22 AV4 4 58 73 12 AV6 4 44 97 26 AVS 4 58 76 14 AVS 4 44 99 10 AV4 4 59 57 14 AVS 4 44 99 10 AV6 4 59 59 10 AV2 4 45 22 11 AV3 4 59 59 12 AVS 4 45 22 10 AVS 4 so 76 16 AV3 4 45 98 19 AVS 4 45 101 9 AV1 4 45 101 6 AVS 4 45 101 9 AVS 4 48 97 10 AV6 4 49 95 8 AV3 4 so 63 17 AV2 4 so 63 23 AV3 4 so 63 18 AV4 4 so 63 11 AVS 4 so 76 12 AV2 1% TWO-Percent Through-wall Depth 2 AV#- Location of AVB intersection with the tube (there are up to 6)

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Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report Mechanical Wear and Wall Loss from Secondary Side Cleaning Processes Table ?lists tube locations and volumetric indications associated with the ultrasonic energy cleaning (UEC) and pressure pulse cleaning (PPC) secondary side cleaning processes. The examinations performed to address this existing degradation mechanism are an element of the bobbin inspection program and+ POINT probe for sizing. Based on these NDE uncertainty levels and the results, it is apparent that there has been no measurable progression in the wall loss associated with these historical indications. Further, the mechanisms that caused this form of degradation are no longer applied and therefore no wear progression can occur. The lack of growth confirms that degradation exceeding the structural and leakage integrity limits is unlikely during the inspection interval of up to three cycles.

The reported Row 1 volumetric indications tubes have also been observed by visual inspection in prior outages. Visually they too resembled tube oxide removal patterns observed in qualification testing for UEC. No foreign objects have been determined to be associated with these tube wear indications. These tubes have been left in service for several inspection intervals with no indications of tube wall loss outside of NDE measurement uncertainties.

During 1R21, the largest indication of mechanical wear and wall loss from secondary side cleaning measured 37% TW. This is much smaller than the 48% TW condition monitoring limit at 3~PNo and meets the SG structural performance criteria. Based on the inspection data presented in Table 7 in comparison to the limits, CM has been met at the 1R21 inspection for degradation associated with indications of wear and wall loss from secondary side cleaning processes.

Table 7: Vogtle 1R21 Tube Wall Loss from Secondary Cleaning Process SG Row Column Volts Indication %TWO Location 1 1 83 0.1 PCT 10 TSH 1 1 87 0.56 PCT 37 TSH 1 58 70 0.26 PCT 22 BPH 2 1 70 0.04 PCT 4 TSC 2 1 70 0.08 PCT 8 TSC 2 1 70 0.05 PCT 5 TSC 2 1 78 0.09 PCT 9 TSC 2 1 78 0.05 PCT 5 TSC 2 1 82 0.04 PCT 4 TSC 2 1 91 0.41 PCT DSS 1 BPC 2 10 101 0.36 PCT INR2 BPH 2 16 6 0.12 PCT 11 BPC 2 16 7 0.34 PCT 27 BPC 1

DSS- Distorted Support Signal. No Degradation Found {NDF) with +POINT Probe 2

1NR -Indication Not Reportable . No Degradation Found {NDF) with +POINT Probe

%TWO-Percent Through-wall Depth BPH-Baffle Plate on the HL side PCT- Volumetric Indication TSC-Tubesheet Region on the CL side TSH-Tubesheet Region on the HL Side BPC-Baffle Plate on the CL side E-19

Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report Mechanical Wear at Tube Support Plate Mechanical wear at the tube support plate is a new damage mechanism reported during 1R21 .

Flow-induced vibrations that cause tube support wear are governed primarily by thermal hydraulic characteristics and the sizes of the as-built tube-to-support gaps. This suggests that the occurrence and wear rates are subject to SG specific conditions and will vary between plants and between SGs at a specific plant.

The bobbin coil is the detection technique for TSP wear flaws. However, with the implementation of the alternate inspection program, not all tubes received full length bobbin coil examination. Table 8 shows the wear at tube support plate locations. The mechanical wear at Tube R20C53 TSP 05H in SG 1 was measured at 5% TW and the wear indicated at Tube R44C21 TSP 07H was measured at 18% TW. Both wear indications were detected by the

+POINT probe.

During 1R21, the largest indication of mechanical wear and wall loss from secondary side cleaning measured 18% TW. This is much smaller than the 53% TW condition monitoring limit at 3~PNo and satisfies the SG structural performance criteria.

Table 8: Vogtle 1 R21 Wear at Tube Support Plate Locations SG Row Column Volts Indication %TWO Location 1 20 53 0.1 PCT 5 5H 1 44 21 0.16 PCT 18 7H SH- Tube Support Plate 5 on HL side 7H- Tube Support Plate 7 on HL side PCT- Foreign Object Wear ODSCC at the Hot Leg Expansion Transitions ODSCC at the hot leg expansion transitions is an existing degradation mechanism for Vogtle 1, and this experience has been considered in the Vogtle 1R21 eddy current inspection scope development in accordance with the guidelines. During 1R21, there were three axial ODSCC indications reported by the +POINT probe analysis in two tubes located at the top of the tubesheet hot leg expansion transition location. Two flaws were contained in Tube R5C90 at TSH-0.24 inch and TSH-0.3 inch below the top of the tubesheet at the bottom of the expansion transition. These two axial ODSCC flaws in Tube R5C90 are circumferentially separated by approximately 150 degrees and are not considered to be interactive since the flaw separation is greater than the 0.25 inch criteria for multiple flaw interaction. In addition, an axial indication was reported in Tube R16C65 at TSH-0.27 inch below the top of the tubesheet. Condition monitoring requirements have been satisfied at the 1R21 inspection for degradation associated with ODSCC at the hot leg expansion transitions.

Table 9 provides a listing of the indications reported with their associated depth and extents.

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Enclosure to N L-19-0204 1R21 Steam Generator Tube Inspection Report Table 9: Vogtle 1R21 Axial ODSCC at Expansion Transitions Max Circ Ext.

Circ Ext.

SG Row Col Volts lnd Depth (deg)

(inches)

%TWO 4 5 90 0.38 SAl 62.3 45 0.27 4 5 90 0.24 SAl 67.7 40 0.24 4 16 65 0.67 SAl 71.0 51 0.30 SAl- Single Axial Indication

%TWO-Percent Through-wall Depth Ind.- Indication Circ. Ext.- Circumferential Extent PWSCC at Tube Bulge and Overexpansion Locations Within Tubesheet There were no PWSCC indications reported from the inspection at tube bulge and overexpansion locations within tubesheet from +POINT probe analyses during 1R21. Therefore, condition monitoring requirements have been satisfied at the 1R21 inspection for tube bulge and overexpansion locations within tubesheet.

PWSCC in the Small Radius U-Bends Axial PWSCC in the Row 1 and 2 U-bends is classified as an existing degradation mechanism in the Vogtle Unit 1 SGs. Both axial and circumferential PWSCC at the U-bends are detectable by +POINT probe inspections.

During 1R21 , an axial PWSCC indication was detected in the U-bend of Tube R 1C58 in SG2.

The location of the indication was near the U-bend apex at TSP 07H+5.05 and was coincident with a geometric anomaly. The maximum depth of the indication was measured at 55% TW with a conservative length of 0.40 inch. The tube was plugged and no stabilizer was installed as there is no potential for future tube severance with axial SCC degradation in the low row U-bend. Table 10 provides a listing of the indication reported with its associated depth and extents.

The critical crack length for which 100% TW axial flaw would satisfy the 3L'lPNoP structural integrity performance criteria is 0.38 inch. The axial length of the indication was 0.40 inch as measured by depth profiling, thus exceeding the critical crack length criteria by a small margin.

The condition monitoring limit for a 0.40 inch axiaiiD part-through-wall flaw is 62% TW. The axiaiiD indication measured in Tube R1 C58 was 55% TW which satisfies the 62% TW condition monitoring limit. The burst pressure for this flaw measuring 55% TW with an axial length of 0.40 inch is 4481 psi, which is in excess of the minimum acceptable 3flPNoP burst pressure limit of 4044 psi. Therefore, condition monitoring structural integrity requirements have been satisfied during 1R21 inspection for degradation associated with PWSCC at the tube small radius U-bends.

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Enclosure to NL-19-0204 1R21 Steam Generator Tube Inspection Report Table 10: Vogtle 1R21 Axial PWSCC in the Small Radius U-Bends Max Circ Ext.

Circ Ext.

SG Row Col Volts lnd Depth (deg)

(inches)

%TWO 2 1 58 1.47 SAl 55 63 0.38 SAl- Single Axial Indication

%TWO-Percent Through-wall Depth Ind.- Indication Circ. Ext.- Circumferential Extent PWSCC at Hot Leg Expansion Transitions Axial PWSCC at hot leg tubesheet expansion transitions was first identified during the last inspection in 1R20. There were no PWSCC indications reported from Hot Leg Expansion Transitions from +POINT probe analyses during 1R21.Therefore, condition monitoring requirements have been satisfied at the 1R21 inspection for degradation associated with PWSCC at the Hot Leg Expansion Transitions.

Tube Plugging/Number of Tubes Plugged Table 11 presents a summary list of all SG tubes plugged in 1R21 and the related degradation mechanism.

Table 11: Vogtle 1 R21 Plugging List SG Row Column Indication Location Plugging Stabilizer Degradation Basis Mechanism 2 1 58 SAl TSP Axial No PWSCC in 7H+5.05 PWSCC the Small Radius U-Bends 4 5 90 SAl TSH -0.24 Axial Yes- HL Axial ODSCC TTS ODSCC at 4 5 90 SAl TSH -0.30 Axial Yes- HL Tubesheet ODSCC TTS Expansion 4 16 65 SAl TSH -0.27 Axial Yes- HL Transitions ODSCC TTS SAl -Single Axial Indication HL TIS- Hot Leg Top of Tubesheet E-22

Enclosure to N L-19-0204 1R21 Steam Generator Tube Inspection Report Table 12: Total Plugged Tubes after Vogtle 1R21 SG #Tubes 1R21 Total %Plugging

1. Plugged #Plugged 1 5,626 0 29 0.52%

2 5,626 1 28 0.50%

3 5,626 0 40 0.71%

4 5,626 2 82 1.46%

Total 22,504 3 179 0.80%

Tube Slippage Monitoring and Leakage Considerations The bobbin data collected have been screened for large amplitude tubesheet indications of greater than 50 volts with a phase angle between 25° and sao suggestive of tube severance from all four SGs showed no tube severance indications reported; therefore, no indications of slippage were identified.

None of the indications reported during the Vogtle 1R21 SG inspections were evaluated to have primary to secondary leakage under accident induced conditions. There was no leakage from the portion of tubing within the H* depth for which to apply the leak rate factor associated with the alternate repair criteria. Since there was no calculated leakage from any other sources none of the Vogtle 1 SGs installed tube plugs require leakage calculations. Therefore, for these indications the accident induced leakage rate would be zero, satisfying the accident induced leakage performance criteria.

Other Inspections SG Channel Head Primary Side Bowl Inspections During Vogtle 1R21, a visual inspection of the SG channel head bowl of the SG hot leg and cold leg divider plate and drain line areas, inclusive of the entire divider plate to channel head weld and all visible clad surfaces, were performed in accordance with Westinghouse NSAL-12-1 and industry operating experience. This inspection was performed using the SG manway channel head bowl cameras. The cladding anomaly previously detected during 1R20 was visually re-inspected during 1R21 and showed no discernable changes in shape or size. No other channel head degradation was observed in any SGs during 1R21.

Secondary Side Activities Discussion During Vogtle 1R21, TIS deposit cleaning sludge lancing was performed in all four SGs. A total of 31.45 pounds of sludge was removed from all four SGs. FOSAR inspections were conducted in the secondary side of all SGs during VEGP 1R21. These FOSAR inspections were performed at the TIS region around the annulus as well as the no-tube lane through the center of the tube bundle. The FOSAR scope also included known E-23

Enclosure to N L-19-0204 1R21 Steam Generator Tube Inspection Report foreign object locations from prior inspections. Secondary side visual inspections were also conducted at locations of historical PLP indications and any new PLP indications identified by the eddy current program.

Condition Monitoring Conclusions Based on the inspection data and the condition monitoring (CM) assessment, no tubes exhibited degradation in excess of the condition monitoring limits. No tubes required in situ pressure testing to demonstrate structural and leakage integrity. There was no reported SG primary to secondary leakage prior to the end of the Vogtle 1 SG inspection interval. No new indications of secondary side tube degradation attributable to foreign objects have been identified. All indications detected in this inspection were below the calculated integrity limits and therefore met the condition monitoring requirements provided. A final OA has been performed considering the indications detected during 1R21 and degradation growth rates. The final OA concludes that steam generator tube structural and leakage integrity will be maintained until the end of the inspection interval when all SGs will be inspected again. Based on application of conservative AVB wear growth rates, the condition of the Vogtle Unit 1 SG tubes has been analyzed with respect to continued operability of the SGs until the end of Cycle 22 without exceeding the performance criteria. The first occurrence of mechanical wear at TSP locations was detected during 1R21. Flaw growth projections for the detected and assumed undetected flaws show that no TSP wear degradation exceeding the structural and leakage integrity limits is anticipated at 1R22.Based on worst-case flaw projection, operation until the end of Cycle 22 is not expected to produce assumed undetected sec flaws that exceed the performance criteria for structural and leakage integrity. This conclusion has been reached based on conservatively applied degradation growth rates using a combination of deterministic and probabilistic methods.

Therefore, the SG performance criteria for structural and leakage integrity were satisfied for the preceding Vogtle 1 SG operating interval for all four SGs.

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