NL-17-1641, Submittal of 1R20 Steam Generator Tube Inspection Report

Submittal of 1R20 Steam Generator Tube Inspection Report

ML17270A321
Person / Time
Site:	Vogtle
Issue date:	09/27/2017
From:	Hutto J Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-17-1641
Download: ML17270A321 (28)

Text

-A Southern Nuclear J. J. Hutto Regulatory Affairs Director 40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 205 992 5872 tel 205 992 7601 fax SEP 2 7 2017 jjhutto@southernco.com Docket Nos.: 50-424 NL-17-1641 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant- Unit 1 1 R20 Steam Generator Tube Inspection Report Ladies and Gentlemen:

In accordance with the requirements of 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 twentieth refueling outage on Unit 1 (1 R20.)

This letter contains no NRC commitments. If you have any questions, please contact Ken McElroy at (205) 992-7369.

Respectfully submitted, fjo/VC?

J. J. Hutto Regulatory Affairs Director JJH/kgl/cg

Enclosure:

1R20 Steam Generator Tube Inspection Report cc: Regional Administrator, Region II NRR Project Manager- Vogtle 1 & 2 Senior Resident Inspector- Vogtle 1 & 2 RType: CVC7000

Vogtle Electric Generating Plant- Unit 1 1R20 Steam Generator Tube Inspection Report Enclosure 1R20 Steam Generator Tube Inspection Report

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Introduction The Vogtle Electric Generating Plant (Vogtle) twentieth refueling outage on Unit 1 (1 R20) was conducted after Steam Generator (SG) service equivalent to 1.36 effective full power years (EFPY) from previous SG eddy current inspections. At Vogtle 1R20, approximately 23.6 effective full power months (EFPM) of the 72 EFPM in the fourth sequential period have been accrued. At the conclusion of Vogtle 1R20, all tubes in-service at the beginning of the period have been inspected. No tube leakage was reported during the operating interval.

Condition Monitoring (CM) and Operational Assessments (OA) analyses based on conservative assumptions demonstrated that no tubes exceeded Regulatory Guide 1.121 or NEI-97-06 Revision 3 criteria for tube integrity during the cycle.

The Westinghouse Nuclear Services Division Steam Generator Maintenance Services Group performed eddy current inspections. NDE Technology performed secondary data analysis under direct contract with Southern Nuclear Operating Company (SNC). During Vogtle 1R20, a total of 12 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.

Vogtle 1R20 SG Scope The 1R20 scope involved the scheduled inspections listed below. In accordance with the EPRI PWR SG Examination Guidelines, Revision 7, the 1R20 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 1R20 included:

• 100% Bobbin examination of tubes in all SGs, full length except for Rows 1 and 2, which are inspected from tube end to the top tube support plate (TSP) from both the hot leg (HL) and the cold leg (CL).

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

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

• 50% +POINT probe examination of HL tubes in all SGs from the top of the tubesheet (TIS) to the licensed alternate repair criteria (ARC) depth for H* (TSH +3/-15.2 inches). This inspection satisfies the required periodic E- 1

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report sample that accompanies regulatory approval of H*. The region encompassed by tube Columns 95 through 122 and Rows 1 through 17 was inspected 100% with +POINT probe from TSH +3/-15.2 inches in SG4 only.

• Scope expanded from 50% to 100% in all four SGs (see below).

• +POINT probe examination of HL and 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. Additionally, all secondary side foreign objects were 'boxed-in' by one tube with +POINT probe TTS +3/-3 inches.

• 50% of the HL tube bulge (BLG)/overexpansion (OXP) populations in all four SGs. This scope is captured as part of the HL tubesheet inspection scope. The BLG and OXP indications are defined as follows:

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

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

• Twenty-five percent {25%) +POINT probe examination of dents and dings

~ 2 Volts in HL straight lengths and U-bends of all SGs. This sample should be taken from the total number of dents and dings identified during previous inspections and any additional identified by the bobbin program.

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

Secondary Side activities performed included:

• Steam Drum inspections in SG1, SG2, and SG3.

Inspection Expansion Vogtle 1R20 SG in-service inspections (lSI) required non-destructive examination (NDE) inspection scope expansion for the hot leg top of tubesheet +POINT probe inspection (+3 inches I -15.21 inches) to be increased from 50% to 100% in each of the four SGs, due to detecting the following degradation mechanisms:

• Circumferential Outer Diameter Stress Corrosion Cracking (ODSCC) at the hot leg top of tubesheet expansion transition.

• Circumferential Pressurized Water Stress Corrosion Cracking (PWSCC) within the hot leg tubesheet region.

• Axial PWSCC at the hot leg top of tubesheet expansion transition.

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Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report This scope expansion also encompasses 100% of the hot leg apparent diameter increase/overexpansion population in each SG located within the H* region (TTS

+3/-15.2 inches).

Damage Mechanisms Found and NDE Techniques Utilized Based on SG eddy current data, the existing degradation mechanisms in the Vogtle 1 SGs are below. With the exception of Axial PWSCC, damage mechanisms found during 1R20 were identified in previous inspections. The 1R20 SG Degradation Assessment identified all of the damage mechanisms found during 1R20 and are listed below with the associated inspection method:

• Mechanical Wear due to Foreign Objects o +Point' and bobbin techniques

• Mechanical Wear at Anti-Vibration Bar (AVB) Supports o Bobbin techniques

• Mechanical Wear and Wall Loss from Secondary Side Cleaning Processes o Bobbin and +Point' techniques

• Circumferential ODSCC at Hot Leg Tubesheet Expansion Transitions o +Point' techniques

• PWSCC at Tube Bulge and Overexpansion Locations and Within Tubesheet o +Point' techniques

• PWSCC at Hot Leg Expansion Transitions (Previously Classified as Potential) o +Point' techniques Service Induced Indication Descriptions Mechanical Wear due to Foreign Objects Foreign objects have been 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 1R20.

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. Additionally, no new foreign object wear associated with known foreign objects in the SG secondary side was observed. During the past outages, visual inspections revealed only sludge and deposits observed.

No new visually observed wear was associated with foreign objects in the SG secondary side that required further analysis. The majority of Table 1 PLP E-3

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report indications are located in SG1 and SG2 and they are all historical. During future operation, these SGs are no more likely to be affected by foreign objects than the others. No PLP signals in Table 1 required SG secondary side visual inspection to determine whether a loose part could be found that was responsible. No indications required SG entry on the secondary side for retrieval during 1R20.

Table 2 lists tube wear indications attributable to loose parts and foreign objects in 1R20. The foreign object wear indications with percent through-wall (PCT) identified show no apparent growth or change outside of measurement uncertainties. During 1 R20, one new volumetric indication was reported in SG2 at Row 54 Column 46 (R54C46) on top of cold leg tubesheet (TSC) . This indication was measured at 15% TW. Review of historical raw +POINT probe data indicates the indication was present during 1R19 with no change. There was no evidence of a PLP associated with this indication. 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 than 36PNO. Based on the inspection data, 1 R20 condition monitoring (CM) has been met for degradation associated with foreign object wear indications.

Table 1: Vogtle 1R20 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 20 60 INA TSH+0.24 1 3 79 PLP TSC+0.08 1 53 80 INA TSC+0.18 1 36 87 PLP TSH+0.08 1 36 88 PLP TSH+0.11 1 14 112 PLP TSH+1.55 1 15 112 PLP TSH+1.59 1 18 116 INA TSC+0.3 1 19 116 INA TSC+0.18 2 18 8 PLP TSH+0.9 2 19 8 PLP TSH+0.75 2 50 35 PLP TSH+0.37 2 51 35 PLP TSH+0.46 2 10 44 INA TSH+0.09 2 35 106 PLP TSH+0.2 2 36 106 PLP TSH+0.18 4 30 18 PLP TSH+1.65 4 31 18 PLP TSH+1 .58 TSH- Tubesheet reg1on on HL s1de 1C- Tube Support Plate 1 on CL s1de 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 INR- Indication Not Reportable E-4

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Table 2: Vogtle 1R20 Foreign Object Wear Indications (PCD SG Row Column Indication Percent 1 Location 1 24 66 PCT 10 3C+27.16 1 55 82 PCT 24 BPH+0.49 1 56 82 PCT 4 BPH+0.62 1 41 97 PCT 25 TSC+0.07 1 39 100 PCT 11 TSH+0.29 1 41 100 PCT 13 TSH+0.18 1 41 100 PCT 29 TSH+0.11 1 41 101 PCT 23 TSH+0.15 1 41 102 PCT 17 TSH+0.15 1 41 103 PCT 22 TSH+0.39 2 6 1 PCT 8 1C+1.25 2 54 46 PCT 152 TSC+0.08 3 29 111 PCT 12 BPH-0.15 3 30 111 PCT 31 BPH+0.77 4 40 57 PCT 5 6H+13.84 4 49 89 PCT 11 BPH+0.34 4 38 104 PCT 14 BPH+0.17 1 lnd1cates ..

the tube percent through wall depth measured by a quahf1ed bobb1n or +Po1nt techmque .

2 Newly reported in 1R20. Indication was sized at 15% TW by +POINT probe in 1R19 based on eddy current raw data review TSH- Tubesheet region on HL side 1C- Tube Support Plate 1 on CL side TSC-Tubesheet region on CL side 6H- Tube Support Plate 6 on HL side 3C- Tube s,upport 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; two of the wear locations exceeded the Technical Specification plugging limit of 40% through-wall (TW). Stabilizer installation was not required for plugging.

During 1R20, the maximum AVB wear indication reported was 43% TW, which occurred in SG3 at R39C104 Antivibration Bar #5 (AV5). Additionally, Tube R51C82 AV4 in SG3 was reported at 41% TW. Both these tubes were plugged because the measured degradation exceeded the Vogtle SG Technical Specification requirement for tube plugging of 40% TW or greater.

These indications had grown in depth by 5% TW and 2% TW, respectively, from the prior inspection. The largest depth AVB wear indication of 43% TW satisfies the 64% TW condition monitoring limit at 3llPNO. CM has been met at the 1R20 inspection for degradation associated with AVB wear.

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Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Table 3: Vogtle 1 R20 SG1 AVB Wear Indications SG Row Column %TWD 1 Location 2 ~

SG Row Column %TWD 1 Location 1 35 16 14 AV4 1 42 37 11 AV6 1 38 16 15 AV1 1 54 37 13 AV1 1 38 16 18 AV2 1 54 37 11 AV5 1 38 16 16 AV3 1 54 37 11 AV6 1 38 16 32 AV4 1 40 38 10 AV4 1 38 16 11 AV5 1 52 39 20 AV2 1 35 18 9 AV6 1 52 39 28 AV3 1 41 18 10 AV4 1 52 39 28 AV4 1 41 18 10 AV5 1 52 39 11 AV5 1 41 18 14 AV6 1 53 39 10 AV6 1 40 20 11 AV4 1 23 40 7 AV6 1 43 21 8 AV2 1 46 41 7 AV1 1 43 21 26 AV4 1 42 43 11 AV2 1 43 21 29 AV5 1 42 43 10 AV3 1 43 21 9 AV6 1 42 43 12 AV4 1 44 21 10 AV3 1 42 43 13 AV5 1 44 21 13 AV4 1 53 43 6 AV2 1 44 21 18 AV5 1 53 43 7 AV5 1 41 23 13 AV3 1 53 43 11 AV6 1 41 23 11 AV4 1 41 44 21 AV2 1 45 26 12 AV3 1 41 44 36 AV3 1 45 26 12 AV5 1 52 44 22 AV4 1 49 28 16 AV4 1 51 45 11 AV6 1 49 28 19 AV5 1 54 45 8 AV2 1 50 29 11 AV1 1 57 45 20 AV2 1 50 29 10 AV2 1 57 45 37 AV3 1 45 30 14 AV3 1 57 45 12 AV5 1 45 30 12 AV5 -

1 57 45 12 AV6 1 52 33 18 AV2 1 40 47 32 AV3 1 52 33 19 AV3 1 40 47 34 AV4 1 35 34 7 AV3 1 40 47 10 AV5 1 35 34 9 AV4 1 40 47 12 AV6 1 40 34 9 AV2 1 42 47 11 AV6 1 40 34 10 AV3 1 57 47 10 AV3 1 40 34 15 AV4 1 57 47 10 AV5 1 40 34 9 AV6 1 39 48 11 AV2 1 41 34 8 AV4 1 39 48 19 AV3 E-6

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 1 42 34 14 AV4 1 39 48 20 AV4 1 45 36 10 AV5 1 36 49 10 AV3 1 54 36 10 AV2 1 58 49 13 AV5 1 58 49 14 AV6 1 52 91 13 AV1 1 41 51 11 AV4 1 40 94 10 AV4 1 58 51 13 AV6 1 39 95 10 AV3 1 54 53 11 AV2 1 41 96 11 AV4 1 54 53 10 AV3 1 41 96 10 AV6 1 40 62 18 AV3 1 42 97 14 AV3 1 40 62 11 AV4 1 48 97 12 AV1 1 40 62 12 AV5 1 47 99 11 AV2 1 59 62 13 AV6 1 27 100 10 AV5 1 40 75 11 AV3 1 37 100 12 AV5 1 58 75 13 AV1 1 37 102 23 AV5 1 58 76 10 AV6 1 44 102 11 AV2 1 37 77 14 AV3 1 32 104 11 AV6 1 43 78 13 AV5 1 35 104 12 AV3 1 41 80 11 AV3 1 35 104 10 AV4 1 44 80 8 AV3 1 39 104 12 AV4 1 44 80 12 AV4 1 40 104 16 AV3 1 44 80 10 AV5 1 40 104 17 AV4 1 43 81 13 AV4 1 36 105 12 AV3 1 43 81 10 AV5 1 34 107 12 AV1 1 43 82 15 AV3 1 34 107 16 AV3 1 43 83 9 AV1 1 38 108 10 AV1 1 43 83 18 AV2 1 38 108 11 AV6 1 43 83 19 AV3 1 28 114 10 AV2 1 43 83 20 AV4 *L.oo-1 26 115 11 AV2 1 43 83 13 AV5 1 26 115 10 AV5 1 54 83 11 AV1 1 27 115 12 AV1 1 54 83 12 AV6 1 27 115 14 AV6 1 43 85 13 AV2 1 28 115 15 AV1 1 39 87 9 AV4 1 28 115 27 AV6 1 53 87 10 AV3 1 23 116 11 AV6 1 49 88 10 AV4 1 24 116 10 AV2 1 39 90 9 AV2 1 24 116 12 AV5 1 39 90 11 AV3 1 26 116 13 AV1 1 45 90 18 AV2 1 26 116 19 AV6 1 45 90 10 AV3 E-7

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column  % TWD 1 Location 2 SG Row Column %TWD 1 Location 1 53 90 15 AV6 1 43 91 32 AV2 1 43 91 18 AV3 1 43 91 15 AV4 E-8

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Table 4: Vogtle 1R20 SG2 AVB Wear Indications SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 2 28 12 11 AV2 2 46 49 11 AV2 2 32 12 7 AV1 2 46 49 24 AV3 2 32 12 19 AV3 2 46 49 19 AV4 2 35 13 10 AV3 2 46 50 25 AV1 2 35 13 11 AV4 2 46 50 35 AV2 2 35 13 10 AV5 2 46 50 34 AV3 2 35 13 8 AV6 2 46 50 31 AV4 2 36 13 6 AV3 ~ 2 46 50 26 AV5 2 35 14 15 AV3 2 46 50 14 AV6 2 35 14 13 AV5 2 46 53 13 AV5 2 35 17 12 AV3 2 46 53 10 AV6 2 35 18 11 AV6 2 42 56 9 AV2 2 39 18 16 AV4 2 46 58 24 AV2 2 39 20 12 AV3 2 46 58 9 AV3 2 40 22 9 AV3 l 2 46 58 11 AV4 2 40 22 9 AV4 2 46 58 13 AV5 2 35 25 9 AV3 2 53 61 10 AV5 2 40 30 12 AV4 ,,_., 2 43 63 15 AV4 2 35 32 12 AV4 2 42 66 11 AV3 2 35 32 10 AV6 2 43 68 12 AV3 2 41 33 25 AV4 2 43 68 13 AV5 2 41 33 21 AV5 2 42 72 17 AV2 2 37 34 8 AV2 2 42 72 19 AV3 2 54 36 10 AV2 2 42 72 15 AV5 2 32 37 10 AV6 ~ --1 2 56 72 12 AV2 2 40 37 14 AV4 2 56 72 14 AV3 2 39 38 19 AV2 2 57 72 9 AV1 2 40 39 10 AV4

--- 2 33 74 11 AV3 2 41 39 10 AV3 2 54 75 9 AV5 2 41 39 14 AV4 2 42 76 9 AV1 2 40 41 9 AV2 2 42 76 30 AV2 2 40 41 13 AV3 2 42 76 22 AV3 2 40 41 10 AV4 2 42 76 21 AV4 2 36 42 12 AV2 2 42 76 37 AV5 2 36 42 12 AV4 2 42 76 20 AV6 2 41 42 20 AV2 2 52 79 10 AV4 2 41 42 12 AV3 2 53 79 12 AV2 2 41 42 30 AV4 2 53 79 17 AV3 E-9

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 2 41 42 36 AV5 2 57 79 11 AV4 2 26 49 10 AV2 2 57 79 11 AV5 2 43 81 8 AV5 2 38 89 12 AV2 2 51 81 12 AV2 2 38 89 10 AV3 2 51 81 15 AV4 2 38 89 12 AV4 2 35 83 13 AV3 2 38 89 17 AV5 2 35 83 10 AV4 2 38 89 11 AV6 2 35 83 19 AV5 2 49 89 13 AV3 2 35 83 14 AV6 2 49 89 23 AV4 2 50 83 12 AV2 2 49 89 23 AV5 2 50 83 10 AV3 2 50 89 16 AV2 2 53 83 32 AV2 2 50 89 15 AV3 2 53 83 28 AV3 2 50 89 34 AV4 2 53 83 12 AV4 2 47 90 9 AV3 2 55 83 15 AV5 2 42 91 18 AV4 2 42 84 15 AV3 2 43 91 28 AV2 2 42 84 10 AV4 2 43 91 18 AV3 2 42 84 16 AV5 2 43 91 8 AV4 2 43 84 11 AV3 2 43 91 25 AV5 2 43 84 13 AV5 2 43 91 11 AV6 2 50 84 11 AV2 2 49 91 10 AV5 2 50 84 30 AV3 2 52 91 17 AV2 2 50 84 32 AV4 2 52 91 10 AV5 2 50 84 12 AV5 2 42 92 17 AV4 2 54 84 9 AV2 2 42 92 14 AV5 2 54 84 19 AV3 I 2 50 92 14 AV2 2 54 84 18 AV4 2 50 92 18 AV3 2 54 84 27 AV5 2 50 92 10 AV4 2 55 84 24 AV5 2 40 93 19 AV2 2 42 86 16 AV3 2 40 93 10 AV3 2 48 86 12 AV4 2 40 93 22 AV5 2 48 86 10 AV5 2 43 93 13 AV2 2 42 87 11 AV2 2 43 93 19 AV3 2 43 87 12 AV2 2 43 93 18 AV4 2 43 87 16 AV3 2 43 93 12 AV5 2 43 87 10 AV4 2 42 94 20 AV3 2 43 87 21 AV5 2 42 94 26 AV4 2 53 87 11 AV5 2 42 94 14 AV5 2 42 88 19 AV4 2 43 94 8 AV2 E- 10

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column  % TWD 1 Location 2 SG Row Column %TWD 1 Location 2 43 88 9 AV2 2 43 94 10 AV3 2 43 88 17 AV3 2 43 94 8 AV4 2 43 88 17 AV5 2 45 94 7 AV3 2 46 94 8 AV4 2 35 105 14 AV5 2 40 95 8 AV3 2 35 105 10 AV6 2 42 95 11 AV2 2 38 105 10 AV5 2 43 95 14 AV4 2 39 105 16 AV2 2 43 95 12 AV5 2 39 105 14 AV3 2 43 95 9 AV6 2 39 105 23 AV5 2 42 96 14 AV2 2 40 105 12 AV2 2 42 96 15 AV3 r< 2 40 105 10 AV3 2 42 96 18 AV4 1 2 40 105 22 AV5 2 42 96 17 AV5 2 34 106 13 AV3 2 43 96 10 AV3 2 38 106 28 AV5 2 43 96 12 AV5 2 38 107 13 AV3 2 44 96 9 AV5 2 38 107 12 AV6 2 46 96 11 AV2 2 34 108 15 AV4 2 37 97 13 AV3 2 36 108 9 AV6 2 42 97 13 AV2 2 38 108 9 AV3 2 42 97 24 AV3 2 38 108 9 AV4 2 42 97 36 AV4 2 30 110 10 AV2 2 42 97 12 AV5 2 28 112 9 AV2 2 40 98 23 AV5 2 28 112 11 AV6 2 46 98 11 AV5 2 27 115 11 AV2 2 48 98 8 AV3 I~ 2 27 115 10 AV5 2 48 98 13 AV4 2 48 98 17 AV5 2 48 98 22 AV6 2 38 99 8 AV3 2 35 100 9 AV5 2 39 100 9 AV5 2 41 100 10 AV3 2 41 100 14 AV5 2 42 100 17 AV3 2 42 100 20 AV4 2 44 100 9 AV4 2 35 101 11 AV5 2 42 101 8 AV2 2 42 101 15 AV4 E- 11

Enclosure to NL-17-1641 VEGP 1 R20 Steam Generator Tube Inspection Report SG Row Column  % TWD 1 Location 2 SG Row Column %TWD 1 Location 2 42 101 14 AVS 2 39 103 36 AVS 2 41 103 19 AVS 2 35 104 11 AV3 E -12

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Table 5: Vogtle 1R20 SG3 AVB Wear Indications SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 3 28 8 16 AV1 3 44 22 12 AV4 3 28 8 20 AV6 3 44 22 18 AV5 3 36 13 15 AV5 3 45 22 13 AV5 3 35 16 11 AV1 3 42 23 7 AV2 3 35 16 17 AV3 3 42 23 10 AV3 3 35 16 12 AV4 3 42 23 28 AV4 3 35 16 12 AV5 3 42 23 14 AV5 3 38 17 12 AV6 3 41 24 11 AV3 3 39 17 12 AV2 3 46 24 15 AV4 3 39 17 27 AV3 3 42 25 11 AV4 3 39 17 21 AV4 3 42 25 8 AV5 3 39 17 10 AV5 3 46 25 8 AV3 3 39 17 28 AV6 3 46 25 12 AV4 3 40 18 10 AV3 3 46 25 15 AV5 3 40 18 12 AV4 3 46 25 10 AV6 3 40 18 12 AV6 3 48 25 10 AV6 3 40 19 9 AV1 3 39 26 31 AV2 3 40 19 15 AV2 3 39 26 13 AV5 3 40 19 10 AV4 3 42 26 17 AV4 3 40 19 19 AV5 f!'j 3 42 26 18 AV5 3 40 19 13 AV6 3 44 26 30 AV2 3 41 19 13 AV3  : 3 47 26 17 AV5 3 41 19 17 AV4 3 42 27 14 AV2 3 41 19 30 AV5 3 42 27 11 AV4 3 39 20 15 AV4 3 42 27 27 AV5 3 41 20 17 AV4 3 48 27 8 AV2 3 41 20 16 AV5 3 42 28 12 AV2 3 39 21 11 AV2 3 42 28 9 AV3 3 39 21 12 AV5 3 42 28 12 AV4 3 41 21 18 AV4 3 42 28 9 AV5 3 41 21 14 AV5 3 42 28 12 AV6 3 42 21 18 AV2 3 36 29 10 AV2 3 42 21 15 AV3 3 39 29 18 AV2 3 42 21 17 AV4 3 42 29 10 AV3 3 42 21 19 AV5 3 42 29 15 AV4 3 42 22 9 AV2 3 42 29 10 AV5 3 42 22 8 AV4 3 40 30 21 AV5 3 42 22 8 AV5 3 40 30 10 AV6 E- 13

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location2 SG Row Column %TWD 1 Location 3 42 22 11 AV6 3 47 30 11 AV5 3 44 22 11 AV3 3 39 32 11 AV3 3 50 33 10 AV3 3 45 46 21 AV4 3 50 33 13 AV4 3 45 46 21 AV5 3 36 34 12 AV2 3 39 48 7 AV4 3 36 34 15 AV5 3 42 48 12 AV3 3 36 34 12 AV6 3 45 48 19 AV2 3 38 34 10 AV2 3 45 48 28 AV3 3 38 34 15 AV4 3 45 48 19 AV5 3 38 34 11 AV5 3 45 48 10 AV6 3 49 34 30 AV4 3 45 49 23 AV2 3 49 34 13 AV5 3 45 49 26 AV3 3 38 35 11 AV5 3 42 50 8 AV1 3 39 35 12 AV2 3 42 50 29 AV2 3 39 35 28 AV3 3 42 50 16 AV3 3 39 35 20 AV4 3 42 50 36 AV4 3 39 35 14 AV5 3 42 50 10 AV5 3 40 35 13 AV4 3 28 51 9 AV5 3 42 35 28 AV4 3 39 51 8 AV3 3 42 35 19 AV5 3 32 52 8 AV1 3 47 35 10 AV2 3 58 52 16 AV6 3 47 35 17 AV4 3 57 53 10 AV6 3 40 38 11 AV6 3 20 55 10 AV2 3 42 38 10 AV6 3 51 55 10 AV3 3 47 38 20 AV2 3 51 55 13 AV4 3 47 38 33 AV4 3 51 55 6 AV5 3 47 38 13 AV5 3 47 56 12 AV3 3 45 40 22 AV3 3 39 57 6 AV2 3 45 40 15 AV4 3 42 58 11 AV2 3 45 40 18 AV5 3 42 58 22 AV3 3 45 40 11 AV6 3 45 61 14 AV3 3 40 41 9 AV3 3 45 61 19 AV4 3 42 43 17 AV2 3 45 61 25 AV5 3 42 43 15 AV5 3 58 61 13 AV1 3 42 43 8 AV6 3 59 61 14 AV4 3 36 44 12 AV2 3 39 62 7 AV4 3 36 44 15 AV5 3 39 63 16 AV3 3 47 45 7 AV2 3 39 63 10 AV5 3 47 45 19 AV4 3 42 63 21 AV4 E- 14

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 3 45 46 11 AV1 3 59 63 14 AV6 3 45 46 35 AV2 3 45 64 26 AV3 3 3

-o<j 45 46 33 AV3 39 66 17 AV3 3 39 66 12 AV4 3 49 96 13 AV4 3 39 66 17 AV5 3 49 96 15 AV5 3 42 66 12 AV3 3 49 96 33 AV6 3 42 66 17 AV4 3 40 97 15 AV3 3 39 67 13 AV3 3 40 97 12 AV4 3 39 67 14 AV4 3 40 98 18 AV2 3 42 67 12 AV3 3 40 98 10 AV3 3

3 45 45 67 67 23 25 AV3 AV4 I 3 3

40 41 98 99 11 11 AV4 AV3 3 59 68 14 AV6 3 41 99 24 AV5 3 38 69 9 AV3 3 40 100 19 AV2 3 45 69 12 AV2 3 40 100 12 AV4 3 45 69 19 AV5 3 40 100 15 AV5 3 45 77 14 AV2 3 41 100 12 AV2 3 45 77 11 AV3 3 41 100 12 AV4 3 45 77 11 AV4 3 45 100 12 AV5 3 39 82 10 AV5 3 40 101 11 AV2 3 45 82 22 AV3 3 40 101 10 AV5 3 45 82 18 AV4 3 39 102 19 AV2 3 51 82 10 AV2 3 39 102 27 AV5 3 51 82 21 AV3 3 40 102 26 AV2 3 51 82 41 AV4 3 40 102 13 AV6 3 51 82 23 AV5 3 41 102 26 AV2 3 50 83 17 AV5 3 41 102 35 AV3 3 53 84 22 AV3 3 41 102 32 AV4 3 53 84 33 AV4 3 41 102 13 AV5 3 53 84 14 AV5 3 41 102 12 AV6 3 50 86 14 AV2 3 42 102 11 AV4 3 50 86 11 AV3 3 42 102 12 AV6 3 50 86 17 AV5 3 44 102 12 AV4 3 54 88 10 AV1 3 41 103 13 AV5 3 54 88 12 AV6 3 41 103 11 AV6 3 41 89 12 AV5 3 39 104 9 AV3 3 40 91 10 AV3 3 39 104 12 AV4 3 49 92 14 AV5 3 39 104 43 AV5 3 51 92 14 AV6 3 40 104 11 AV2 E -15

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 3 49 93 11 AV6 3 40 104 21 AV4 3 47 95 11 AV6 3 40 104 11 AV5 3 40 96 10 AV3 3 40 104 16 AV6 3 47 96 26 AV4 3 40 105 13 AV6 3 37 106 10 AV6 3 38 106 17 AV3 3 38 106 12 AV5 3 38 106 17 AV6 3 40 106 15 AV6 3 37 107 14 AV1 3 37 107 11 AV4 3 37 107 12 AV5 3 38 107 12 AV4 3 37 108 10 AV1 3 37 108 11 AV2 3 37 108 13 AV6 3 34 110 12 AV4 3 25 115 7 AV2 .._.

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Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Table 6: Vogtle 1R20 SG4 AVB Wear Indications SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 4 27 8 18 AV6 4 54 36 9 AV5 4 27 9 16 AV5 4 39 37 10 AV2 4 30 9 18 AV2 4 39 37 10 AV3 4 30 9 36 AV5 4 54 38 9 AV1 4 33 12 12 AV2 4 54 38 10 AV5 4 33 12 11 AV3 4 54 38 6 AV6 4 33 12 7 AV4 4 36 39 22 AV3 4 33 12 11 AV6 4 40 39 15 AV3 4 36 13 9 AV1 4 28 40 19 AV5 4 36 13 9 AV2 4 30 40 11 AV2 4 36 14 10 AV1 4 30 40 16 AV5 4 34 15 8 AV5 4 30 40 10 AV6 4 38 19 10 AV5 4 55 40 11 AV6 4 30 20 10 AV2 4 56 41 10 AV5 4 42 20 10 AV6 4 27 43 10 AV5 4 45 22 12 AV5 4 43 46 22 AV6 4 41 23 11 AV2 4 58 48 8 AV5 4 40 24 13 AV5 4 27 51 11 AV2 4 40 25 10 AV3 4 39 51 13 AV4 4 40 29 12 AV2 4 39 51 12 AV5 4 33 34 11 AV3 4 39 51 15 AV6 4 33 34 10 AV4 4 38 52 8 AV3 4 33 34 11 AV5 4 38 52 12 AV4 4 38 35 9 AV2 4 38 55 8 AV4 4 39 56 10 AV2 4 28 82 10 AV2 4 39 56 17 AV3 4 28 82 12 AV5 4 39 56 13 AV4 4 40 82 12 AV2 4 40 56 16 AV3 4 40 82 23 AV3 4 59 57 16 AV5 4 40 82 35 AV4 4 39 58 10 AV2 4 40 82 19 AV5 4 39 58 23 AV4 4 55 82 11 AV4 4 39 58 13 AV6 4 55 82 13 AV5 4 59 59 12 AV2 4 40 84 14 AV2 4 40 62 25 AV2 4 40 84 10 AV5 4 40 62 35 AV3 4 30 85 10 AV2 4 40 62 28 AV4 4 43 85 12 AV2 4 40 62 12 AV5 4 38 86 13 AV4 4 50 63 18 AV2 4 40 86 11 AV4 E- 17

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 4 50 63 26 AV3 4 40 86 9 AV5 4 50 63 19 AV4 4 40 87 15 AV4 4 50 63 13 AV5 4 40 87 18 AV5 4 28 65 10 AV5 4 54 87 10 AV2 4 58 65 12 AV1 4 54 87 13 AV4 4 43 66 17 AV2 4 40 88 13 AV3 4 43 66 15 AV3 4 40 88 19 AV4 4 58 73 13 AV6 4 40 88 15 AV5 4 38 74 10 AV2 4 40 88 13 AV6 4 39 75 15 AV5 4 53 89 13 AV4 4 38 76 16 AV3 4 40 90 8 AV3 4 38 76 19 AV4 4 40 90 15 AV4 4 38 76 7 AV6 4 40 90 8 AV5 4 50 76 12 AV2 4 53 90 9 AV1 4 50 76 15 AV3 4 53 90 11 AV5 4 50 76 15 AV4 4 53 90 10 AV6 4 50 76 29 AV5 4 33 91 8 AV2 4 58 76 13 AV5 4 44 91 13 AV5 4 39 78 10 AV5 4 40 92 9 AV3 4 40 78 18 AV2 4 40 92 13 AV5 4 40 78 17 AV3 4 43 92 13 AV3 4 40 78 10 AV5 4 40 93 15 AV2 4 36 79 19 AV4 4 40 93 12 AV5 4 37 80 7 AV4 4 43 93 10 AV4 4 40 80 12 AV3 4 39 95 11 AV4 4 56 81 13 AV6 4 40 95 11 AV2 4 40 95 25 AV4 4 36 104 9 AV5 4 40 95 11 AV5 4 38 104 9 AV3 4 49 95 10 AV3 4 38 104 19 AV4 4 38 96 15 AV2 4 38 104 12 AV5 4 38 96 8 AV4 4 42 104 16 AV3 4 38 96 10 AV5 4 42 104 9 AV4 4 44 96 7 AV2 4 36 105 8 AV2 4 44 96 31 AV3 4 36 105 11 AV5 4 44 96 23 AV4 4 40 105 9 AV2 4 44 96 13 AV6 4 40 105 17 AV4 4 41 97 13 AV5 4 40 105 18 AV5 4 44 97 22 AV2 4 41 105 9 AV3 4 44 97 22 AV4 4 32 106 12 AV3 E -18

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report SG Row Column %TWD 1 Location 2 SG Row Column %TWD 1 Location 4 44 97 25 AV5 4 36 106 7 AV5 4 48 97 10 AV6 4 36 106 9 AV6 4 45 98 16 AV5 4 40 106 10 AV2 4 41 99 13 AV5 4 40 106 18 AV3 4 44 99 10 AV6 4 40 106 19 AV4 4 40 100 12 AV2 4 40 106 29 AV5 4 40 100 9 AV3 4 32 107 10 AV2 4 40 100 11 AV4 4 36 107 10 AV3 4 40 100 10 AV5 4 37 107 15 AV3 4 40 100 8 AV6 4 39 107 9 AV3 4 42 100 16 AV2 4 33 108 12 AV3 4 42 100 14 AV3 4 38 108 15 AV4 4 42 100 17 AV4 4 36 109 10 AV3 4 42 100 11 AV6 4 32 110 10 AV3 4 42 101 15 AV3 4 33 110 22 AV3 4 42 101 21 AV4 4 33 110 11 AV5 4 42 101 25 AV5 4 33 110 7 AV6 4 43 101 13 AV3 4 31 111 9 AV1 4 43 101 14 AV4 4 31 111 11 AV2 4 43 101 26 AV5 4 32 111 8 AV1 4 45 101 9 AV1 4 32 111 13 AV3 4 45 101 9 AV5 4 32 111 9 AV4 4 45 101 7 AV5 4 33 111 18 AV3 4 38 103 11 AV4 4 33 111 19 AV4 4 38 103 8 AV5 4 33 111 17 AV6 4 36 104 12 AV2 4 30 113 10 AV5 4 36 104 7 AV3 4 30 114 28 AV5 10

/o lWD-Percent Through-wall Depth 2 AV#- Location of AVB intersection with the tube (there are up to 6)

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. 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.

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Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report 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. Based on the inspection data presented in Table 7 in comparison to the limits, CM has been met at the 1R20 inspection for degradation associated with indications of wear and wall loss from secondary side cleaning processes.

Table 7: Vogtle 1 R20 Tube Wall Loss from Secondary Cleaning Process SG Row Column Volts Indication %TWO Location 1 1 83 0.13 PCT 12 TSH 1 1 87 0.57 PCT 37 TSH 1 58 70 0.31 PCT 24 BPH 2 1 70 0.06 PCT 7 TSC 2 1 70 0.08 PCT 8 TSC 2 1 70 0.04 PCT 5 TSC 2 1 78 0.05 PCT 5 TSC 2 1 78 0.1 PCT 10 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 13 BPC 2 16 7 0.37 PCT 30 BPC 1DSS- Distorted Support S1gnal. No Degradation Found (NDF) w1th +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 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 1R20 eddy current inspection scope development in accordance with the guidelines. No indications of axial ODSCC in the HL expansion transitions were detected in the 100% +POINT probe examination in all four SGs during Vogtle 1R20.

A total of five circumferential ODSCC indications in the HL expansion transitions were detected in SG2, SG3, and SG4 by the 100% +POINT probe examination.

Condition monitoring requirements have been satisfied at the 1R20 inspection for degradation associated with ODSCC at the hot leg expansion transitions.

Table 8 provides a listing of the indications reported with their associated depth and extents.

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Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Table 8: Vogtle 1 R20 Circumferential ODSCC at Expansion Transitions Max Circ PDA Depth Ext. Circ Ext.

SG Row Col Volts lnd

%TW (deg) (inches)

D 2 15 62 0.6 SCI 43 40 0.24 4.8 2 38 72 0.1 SCI 21 52 0.31 3.0 3 19 103 0.16 SCI 31 35 0.22 3.0 4 31 86 0.22 SCI 63 32 0.10 5.6 4 32 88 0.17 SCI 53 35 0.18 5.2

%lWD-Percent Through-wall Depth Ind. - Indication SCI - Single circumferential indication Circ. Ext.- Circumferential Extent PDA - Percent degraded area PWSCC at Tube Bulge and Overexpansion Locations Within Tubesheet During 1R20, four (4) indications of circumferential PWSCC were detected during the 100% +POINT probe hot leg tubesheet inspection program. The indications were not associated with a known BLG/OXP location, but were located at areas of smaller non-reportable geometric anomalies. All indications were confirmed with the Ghent probe. The largest indication was measured at 69% TW with a 29-degree circumferential extent.

No measurable primary to secondary leakage was identified during the current operating interval, therefore the H* leak rate factor does not apply. Therefore, condition monitoring requirements have been satisfied at the Vogtle 1R20 inspection for degradation associated with PWSCC at the tube bulge and overexpansion locations and locations within the tubesheet. The largest indication (SG2 R40C78), located 15.52 inches below the TTS, which is just below the H* distance of 15.21 inches, was treated conservatively. Due to close H* proximity and measurement uncertainty for eddy current probe travel distance, this tube was preventatively plugged.

Table 9: Vogtle 1 R20 Circumferential PWSCC Within the Tubesheet Circ Circ PDA Ext. Ext.

SG Row Col Volts lnd %TWO (deg) (inche s) 1 14 3 0.15 SCI 34 31 0.18 2.9 2 40 78 0.19 SCI 69 29 0.18 5.6 2 53 83 0.18 SCI 11 28 0.17 1.0 3 29 83 0.14 SCI 0 28 0.17 0

%lWD-Percent Through-wall Depth SCI - Single circumferential indication Circ. Ext.- Circumferential Extent PDA - Percent degraded area E- 21

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report PWSCC in the Small Radius U-Bends There were no PWSCC indications reported from the inspection of small radius U-bends from +POINT probe analyses during 1R20. None have been identified since 1R 15. Therefore, condition monitoring requirements have been satisfied at the 1R20 inspection for degradation associated with PWSCC at the tube small radius U-bends.

PWSCC at Hot Leg Expansion Transitions (Previously Classified as Potential)

The 1R20 degradation assessment identified PWSCC at hot leg tubesheet expansion transitions as a potential degradation mechanism. Vogtle Unit 1 had not experienced this degradation mechanism prior to 1R20. The basis for a potential degradation mechanism was the Surry Unit 1 experience. During the 2009 SG inspection, Surry Unit 1 identified one indication attributed to axial PWSCC at the HL expansion transition in an Alloy 600TT tube.

During the Vogtle 1R20 SG hot leg top of tubesheet +POINT probe inspection program, one axial PWSCC indication at the hot leg expansion transition was detected, confirmed with the Ghent probe. This is the first occurrence of PWSCC at hot leg tubesheet expansion transitions detected in the Vogtle Unit 1 SGs. The indication was depth sized at 85% TW with an axial extent of 0.24 inch. The critical crack length for condition monitoring of axial PWSCC is 0.386 inch, with a structural limit of 0.46 inch. The critical crack length is the length of an axial crack which satisfies the structural performance criteria regardless of its depth (i.e., up to 100% TW). Since the flaw detected had a measured axial extent of 0.24 inch and is less than the critical crack length of 0.386 inch, the structural performance criteria for condition monitoring is met. For the axial indication detected during 1R20 the ligament tearing pressure is 3419 psi, with all NDE, material and burst relation uncertainties included at 0.95 probability and 50% confidence level. This is in excess of the limiting accident differential pressure of 2560 psi. Therefore, no leakage would be expected at accident conditions and the SG AILPC criteria have also been satisfied.

Therefore, condition monitoring requirements have been satisfied at the 1R20 inspection for degradation associated with axial PWSCC at the hot leg expansion transitions.

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Enclosure to NL-17-1641 VEGP 1 R20 Steam Generator Tube Inspection Report Table 10: Vogtle 1R20 Axial PWSCC at Tubesheet Expansion Transitions Axial SG Row Col Volts lnd %TWO Extent (inches) 2 2 68 0.58 SAl 85 0.24

%TWO-Percent Through-wall Depth Ind. - Indication SAl - Single Axial Indication PDA - Percent degraded area Tube Plugging/Number of Tubes Plugged A 100% visual inspection of tube plugs in all four SGs has been performed from the primary side during Vogtle 1R20. No anomalous conditions, such as a degraded tube plug or surrounding boron deposits, were reported during performance of these visual inspections.

During Vogtle 1R20, in total twelve (12) tubes were plugged including one (1) in SG1, five (5) in SG2, four (4) in SG3 and two (2) in SG4. Two tubes in SG3 were plugged due to anti-vibration bar (AVB) wear, which met the Vogtle Unit 1 SG Technical Specification limit for plugging of 40% through-wall (TW). Five tubes were plugged due to circumferential outer diameter stress corrosion cracking (ODSCC) at the hot leg top of tubesheet expansion transition. Four tubes were plugged due to circumferential primary water stress corrosion cracking (PWSCC) contained within the hot leg tubesheet. One tube was plugged in SG2 for axial PWSCC at the hot leg tubesheet expansion transition. The total number of plugged tubes in each SG is summarized in Table 11. The status of the total tubes plugged at Vogtle Unit 1 after the outage is presented in Table 12.

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Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Table 11: Vogtle 1R20 Plugging List SG Row Column Indication Location Plugging Stabilizer Basis 1 14 3 SCI TSH-13.08" Circ PWSCC Yes 2 15 62 SCI TSH-0.01" Circ ODSCC Yes 2 2 68 SAl TSH-0.17" Axial Yes PWSCC 2 38 72 SCI TSH-0.06" Circ ODSCC Yes 2 40 78 SCI TSH-15.52" Circ PWSCC Yes 2 53 83 SCI TSH-13.62 Circ PWSCC Yes 3 51 82 PCT AV4 AVB Wear No 3 29 83 SCI TSH-0.3" Circ PWSCC Yes 3 19 103 SCI TSH-0.09" Circ ODSCC Yes 3 39 104 PCT AVS AVB Wear No 4 31 86 SCI TSH-0.13" Circ ODSCC Yes 4 32 88 SCI TSH-0.13" Circ ODSCC Yes SCI - Smgle c1rcumferent1al 1nd1cat1on SAl - Single Axial Indication PCT- Volumetric Indication Circ. Ext.- Circumferential Extent TSH - Tubesheet Region on the HL Side Table 12: Total Plugged Tubes after Vogtle 1R19 SG #Tubes 1R20 Total %Plugging

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

2 5,626 5 27 0.48%

3 5,626 4 40 0.71%

4 5,626 2 80 1.42%

Total 22,504 12 176 0.78%

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 50° 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 1 R20 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.

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Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report Other Inspections SG Channel Head Primary Side Bowl Inspections During Vogtle 1R20, 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.

As result of the channel head visual inspections, a cladding anomaly was noted in the SG 1 cold leg channel head. The anomaly was located approximately 14 inches from the divider plate and almost 4 inches below the primary face of the tubesheet. It measured approximately 7/16 inch long and 1/8 inch to 3/16 inch wide. Westinghouse Engineering evaluated the anomaly as acceptable for continued operation with no repair required in 1R20. The Westinghouse Engineering evaluation requires that the anomaly be monitored in the future during planned visual inspections of the SG 1 channel head to demonstrate continued compliance with Section XI of the ASME Code.

Secondary Side Activities Upper Steam Drum Inspection An SG steam drum upper internals and feedring inspection was performed during Vogtle 1R20 in SG1, SG2, and SG3. The upper internals of SG4 were not inspected during 1R20, but rather were inspected during 1R19. There were no structurally significant anomalies observed during the inspection of SG1, SG2 and SG3 upper internals. Minor areas of ongoing degradation in the form of pipe base metal wall loss were identified through the UT wall thickness measurements of the feedring piping. None of these conditions presented an immediate concern to the continued operation of these components or the integrity of the SG tubing.

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 1R20 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 E- 25

Enclosure to NL-17-1641 VEGP 1R20 Steam Generator Tube Inspection Report 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 21 and to the end of Cycle 23, without exceeding the performance criteria. Based on worst-case flaw projection, operation until the end of Cycle 21 and Cycle 23 is not expected to produce assumed undetected SCC 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. The condition of the Vogtle SG upper internal components has been found acceptable for the continued operation and presents no concerns to the integrity of the SG tubing.

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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