NL-20-1086, Refueling Outage 1R22 Steam Generator Tube Inspection Report
| ML20262G974 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 09/17/2020 |
| From: | Gayheart C Southern Nuclear Company |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-20-1086 IR22 | |
| Download: ML20262G974 (26) | |
Text
A Southern Nuclear Cheryl A. Gayheart Regulatory Affairs Director 3535 Colonnade Parkway Birmingham, AL 35243 205 992 5316 cagayhea@southernco.com September 17, 2020 Docket Nos.: 50-424 NL-20-1086 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant - Unit 1 Refueling Outage 1R22 Steam Generator Tube Inspection Report Ladies and Gentlemen:
In accordance with the requirements of Vogtle Electric Generating Plant Technical Specification 5.6.10, Southern Nuclear Operating Company submits the enclosed report of the steam generator tube inspections performed during the twenty second refueling outage on Unit 1 (1R22).
This letter contains no NRC commitments. If you have any questions, please contact Jamie Coleman at 205.992.6611.
Respectfully submitted, Cheryl A. Gayheart Regulatory Affairs Director CAG/dsp/sm
Enclosure:
1R22 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 Refueling Outage 1R22 Steam Generator Tube Inspection Report Enclosure 1R22 Steam Generator Tube Inspection Report
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report Introduction The Vogtle Electric Generating Plant (VEGP) twenty-second refueling outage on Unit 1 (1R22) outage was conducted after Steam Generator (SG) service equivalent to 1.41 effective full power years (EFPY) from previous SG eddy current inspections. During this operational interval, no tube leakage was reported. Approximately 57.64 effective full power months (EFPM) of the 72 EFPM in the fourth sequential period have been accrued at Vogtle 1R22. VEGP 1R22 is the fourth 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 22.
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 1R22, a total of four 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 (TTS) -15.2 inches. TTS inspections ranged from TTS +3 inches to TTS -15.2 inches. The scope and results of inspections on each SG, are described below.
Vogtle 1R22 SG Scope The scope for 1R22 involved the scheduled inspections listed below. In accordance with the EPRI PWR SG Examination Guidelines, Revision 8, the 1R22 program addressed Vogtle 1 degradation mechanisms observed from prior inspections as well as those regarded as potential degradation mechanisms. In-service inspection (ISI) examination used Bobbin and Rotating Pancake Coil (RPC) +Point' Eddy Current Testing (ECT) inspection methods. Scope during 1R22 included:
Full-length bobbin of 53% of all inservice tubes in all SGs, but the amount varied by SG; 52%, 45%, 57%, and 57% in SGs 1, 2, 3 and 4 respectively. Bobbin coil inspection is full length except for Rows 1 and 2, which are inspected from tube end to the top TSP from both HL and CL. This inspection included all previously detected indications of degradation and all tubes containing high residual stress.
+POINT probe examination of 100% for Row 1 and 50% for Row 2 U-bends from the top tube support plate (TSP) on the hot leg (HL) side to the top TSP on the cold leg (CL) side in all SGs.
100% +POINT' probe examination of HL tubes in SG1 and SG2 and 50% in SG3 and SG4 from the TTS 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*.
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Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report 100% +POINT of the HL tube bulge (BLG) and overexpansion (OXP) populations in SG1 and SG2 and 50% in SG3 and SG4. This scope was captured as part of the HL tubesheet inspection scope.
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.
100% +POINT probe examination of the 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.
+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 listed in the degradation assessment and any existing possible loose part (PLP) indications from the most recent inspection were boxed-in by at least one tube with +POINT probe. There were no new PLP signals reported in 1R22.
25% +POINT probe examination of dents and dings 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.
25% +POINT probe examination of dents and dings >5 volts in CL straight length tubing in all SGs.
100% +POINT probe examination of all HL and CL TSP intersections, HL and CL TTS expansion transitions and all dents and dings 2 volts of high residual 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.
No Secondary Side activities performed during 1R22.
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Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report Inspection Expansion Vogtle 1R22 SG in-service inspections (ISI) required no scope expansions.
Damage Mechanisms Found and NDE Techniques Utilized Many of the damage mechanisms found during 1R22 inspections were identified in previous inspections and in the 1R22 SG Degradation Assessment. 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 SGs 1 and 2. + 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 SGs 1 and 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 1R22.
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 no new reported PLP signals in 1R22. No evidence of tube wear associated with these PLP signals was detected through eddy current testing.
Table 2 lists tube wear indications attributable to foreign objects in 1R22. The majority of the indications with percent through-wall (PCT) identified have been present for several cycles showing no apparent growth or change outside of measurement uncertainties. The exceptions are two foreign object indications at SG1, Row 1 Column 2 (R1C2) and R23C28. R1C2 indication has not been previously reported, but lookback showed a precursor signal. For R23C28, there was no precursor signal found in the prior inspection of this tube at 1R20. There E-3
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report was no evidence of a foreign object associated with this indication at this tube or surrounding tubes detected using eddy current testing. Secondary side visual inspection of the affected tube and vicinity was not performed during 1R22. The SG1, R23C28 tube was preventatively removed from service.
In 1R22, the largest volumetric wear flaw was measured at 32% through-wall (TW). The through-wall depth is less than the volumetric wear condition monitoring limit of 48% TW at 3PNO. 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 3PNO. Based on the inspection data,1R22 condition monitoring (CM) has been met for degradation associated with foreign object wear indications.
Table 1: Vogtle 1R22 Possible Loose Part Indications (PLP)
SG Row Column Indication (1) Location 1 25 8 PLP TSH + 0.67 1 25 9 PLP TSH +0.56 1 1 55 PLP (2) TSH+0.26 1 36 87 PLP TSH+0.07 1 36 88 PLP TSH+0.11 1 14 112 PLP TSH+1.55 1 15 112 PLP TSH+1.59 2 18 8 PLP TSH +0.84 2 19 8 PLP TSH +0.94 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 INR TSH +1.49 4 31 18 INR TSH +1.69 (1) PLP - Possible Loose Part, INR - Indication Not Reportable (2) Historic PLP, last reported 1R17 TSH- Tubesheet region on HL side TSC-Tubesheet region on CL side E-4
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report Table 2: Vogtle 1R22 Foreign Object Wear Indications (PCT)
SG Row Column Indication Percent1 Location 1 1 2 PCT 11 BPH+15.88 1 23 28 PCT 27 TSH+0.4 1 24 66 PCT 7 3C +27.33 1 39 100 PCT 13 TSH +0.34 1 41 97 PCT 23 TSC +0.09 1 41 100 PCT 15 TSH +0.26 1 41 100 PCT 32 TSH +0.2 1 41 101 PCT 24 TSH +0.14 1 41 102 PCT 19 TSH +0.15 1 41 103 PCT 21 TSH +0.45 1 55 82 PCT 24 BPH +0.54 1 56 82 PCT 5 BPH +0.68 2 6 1 PCT 6 1C +1.22 2 53 48 PCT 9 TSC +0.34 2 54 46 PCT 13 TSC +0.1 3 29 111 PCT 10 BPH -0.22 3 30 111 PCT 31 BPH +0.88 4 38 104 PCT 12 BPH +0.18 4 40 57 PCT 10 6H +13.25 4 49 89 PCT 8 BPH +0.32 1
Indicates the tube percent through wall depth measured by a qualified bobbin or +Point technique.
TSH Tubesheet region on HL side 1C Tube Support Plate 1 on CL side TSCTubesheet 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 AVB Supports The complete listing of AVB wear locations and eddy current signals is provided in Table 3 through 6. All tubes with previous AVB wear locations in each SG have been examined. There was one wear location (SG2 R39C103 AV5) which exceeded the Technical Specification plugging limit of 40% TW.
During 1R22, the maximum AVB wear indication reported was 41% TW which occurred at one location; SG2 at R39C103 AV5. The largest depth AVB wear indication of 41% TW satisfies the 67% TW condition monitoring limit at 3PNO. CM has been met at the 1R22 inspection for degradation associated with AVB wear.
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Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report Table 3 : Vogtle 1R22 SG1 AVB Wear Indications SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 1 23 40 7 AV6 1 38 108 8 AV1 1 23 116 11 AV5 1 38 108 10 AV6 1 24 116 13 AV2 1 39 48 15 AV2 1 24 116 14 AV5 1 39 48 24 AV3 1 26 115 12 AV2 1 39 48 25 AV4 1 26 115 10 AV5 1 39 48 16 AV5 1 26 116 15 AV2 1 39 87 8 AV4 1 26 116 22 AV5 1 39 90 9 AV2 1 27 100 9 AV5 1 39 90 11 AV3 1 27 115 11 AV1 1 39 95 11 AV3 1 27 115 13 AV6 1 39 104 11 AV4 1 28 114 10 AV2 1 40 20 15 AV4 1 28 115 16 AV1 1 40 34 10 AV2 1 28 115 26 AV6 1 40 34 12 AV3 1 32 104 10 AV6 1 40 34 17 AV4 1 34 107 10 AV1 1 40 34 9 AV6 1 34 107 16 AV3 1 40 38 12 AV3 1 35 16 18 AV4 1 40 38 14 AV4 1 35 18 11 AV6 1 40 47 32 AV3 1 35 34 8 AV3 1 40 47 34 AV4 1 35 34 10 AV4 1 40 47 10 AV5 1 35 104 11 AV3 1 40 47 11 AV6 1 35 104 9 AV4 1 40 62 20 AV3 1 36 49 6 AV3 1 40 62 12 AV4 1 36 105 12 AV3 1 40 62 11 AV5 1 37 77 15 AV3 1 40 75 10 AV3 1 37 77 12 AV6 1 40 94 9 AV4 1 37 100 13 AV5 1 40 104 16 AV3 1 37 102 22 AV5 1 40 104 16 AV4 1 37 102 11 AV6 1 41 18 10 AV4 1 38 16 20 AV1 1 41 18 10 AV5 1 38 16 21 AV2 1 41 18 17 AV6 1 38 16 19 AV3 1 41 23 10 AV2 1 38 16 31 AV4 1 41 23 19 AV3 1 38 16 11 AV5 1 41 23 14 AV4 1 38 16 11 AV6 1 41 34 6 AV4 1 38 62 12 AV4 1 41 44 24 AV2 E-6
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 1 41 44 37 AV3 1 44 75 11 AV6 1 41 50 10 AV4 1 44 80 9 AV3 1 41 50 10 AV5 1 44 80 12 AV4 1 41 51 8 AV2 1 44 80 10 AV5 1 41 51 12 AV4 1 44 102 10 AV2 1 41 80 11 AV3 1 45 26 14 AV3 1 41 96 10 AV4 1 45 26 12 AV5 1 41 96 10 AV6 1 45 30 16 AV3 1 42 34 15 AV4 1 45 30 14 AV5 1 42 37 13 AV6 1 45 36 12 AV5 1 42 43 10 AV2 1 45 90 18 AV2 1 42 43 9 AV3 1 45 90 11 AV3 1 42 43 12 AV4 1 46 41 5 AV1 1 42 43 13 AV5 1 46 75 11 AV6 1 42 47 9 AV6 1 47 99 10 AV2 1 42 97 13 AV3 1 48 97 12 AV1 1 42 97 13 AV4 1 49 28 20 AV4 1 43 21 8 AV2 1 49 28 24 AV5 1 43 21 12 AV3 1 49 88 9 AV4 1 43 21 33 AV4 1 50 28 11 AV3 1 43 21 35 AV5 1 50 29 15 AV1 1 43 21 7 AV6 1 50 29 11 AV2 1 43 23 11 AV4 1 51 45 10 AV6 1 43 75 11 AV6 1 52 33 21 AV2 1 43 78 17 AV5 1 52 33 22 AV3 1 43 81 13 AV4 1 52 39 19 AV2 1 43 81 10 AV5 1 52 39 25 AV3 1 43 82 16 AV3 1 52 39 33 AV4 1 43 83 9 AV1 1 52 39 11 AV5 1 43 83 19 AV2 1 52 44 21 AV4 1 43 83 20 AV3 1 52 44 11 AV5 1 43 83 21 AV4 1 52 91 11 AV1 1 43 83 14 AV5 1 53 39 12 AV6 1 43 85 14 AV2 1 53 43 7 AV2 1 43 91 32 AV2 1 53 43 8 AV5 1 43 91 19 AV3 1 53 43 11 AV6 1 43 91 16 AV4 1 53 87 9 AV3 1 44 21 17 AV3 1 53 90 13 AV3 1 44 21 17 AV4 1 53 90 17 AV6 1 44 21 20 AV5 1 54 36 13 AV2 E-7
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 1 54 37 18 AV1 1 57 45 11 AV5 1 54 37 12 AV5 1 57 45 13 AV6 1 54 37 12 AV6 1 57 47 9 AV3 1 54 41 11 AV4 1 57 47 11 AV5 1 54 41 11 AV6 1 57 47 11 AV6 1 54 45 8 AV2 1 57 57 11 AV6 1 54 53 9 AV2 1 58 49 14 AV5 1 54 53 9 AV3 1 58 49 13 AV6 1 54 83 10 AV1 1 58 51 13 AV6 1 54 83 12 AV6 1 58 75 13 AV1 1 55 41 11 AV4 1 58 76 13 AV6 1 55 41 12 AV6 1 59 59 12 AV5 1 57 45 17 AV2 1 59 62 12 AV6 1 57 45 39 AV3 1% TWD-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-20-1086 1R22 Steam Generator Tube Inspection Report Table 4: Vogtle 1R22 SG2 AVB Wear Indications SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 2 26 49 11 AV2 2 37 97 13 AV3 2 27 115 9 AV2 2 38 89 11 AV2 2 27 115 10 AV5 2 38 89 10 AV3 2 28 12 8 AV2 2 38 89 10 AV4 2 28 112 10 AV2 2 38 89 14 AV5 2 28 112 11 AV6 2 38 89 9 AV6 2 30 110 10 AV2 2 38 92 10 AV6 2 32 12 6 AV1 2 38 99 7 AV3 2 32 12 22 AV3 2 38 105 11 AV5 2 32 37 8 AV6 2 38 106 30 AV5 2 33 74 10 AV3 2 38 107 13 AV3 2 34 106 14 AV3 2 38 107 10 AV4 2 34 108 17 AV4 2 38 107 10 AV6 2 35 13 11 AV3 2 38 108 10 AV3 2 35 13 12 AV4 2 38 108 11 AV4 2 35 13 12 AV5 2 39 18 14 AV4 2 35 13 10 AV6 2 39 20 13 AV3 2 35 14 16 AV3 2 39 22 15 AV3 2 35 14 14 AV5 2 39 38 19 AV2 2 35 16 11 AV2 2 39 92 10 AV6 2 35 17 14 AV3 2 39 100 9 AV5 2 35 18 11 AV6 2 39 103 10 AV4 2 35 25 11 AV3 2 39 103 41 AV5 2 35 32 12 AV4 2 39 105 16 AV2 2 35 32 9 AV6 2 39 105 15 AV3 2 35 83 11 AV3 2 39 105 24 AV5 2 35 83 7 AV4 2 40 22 12 AV3 2 35 83 19 AV5 2 40 22 11 AV4 2 35 83 13 AV6 2 40 30 9 AV4 2 35 100 9 AV5 2 40 37 15 AV4 2 35 101 12 AV5 2 40 39 10 AV4 2 35 104 11 AV3 2 40 41 11 AV2 2 35 105 14 AV5 2 40 41 15 AV3 2 35 105 8 AV6 2 40 41 11 AV4 2 36 13 7 AV3 2 40 93 17 AV2 2 36 42 10 AV2 2 40 93 8 AV3 2 36 42 10 AV4 2 40 93 20 AV5 2 36 108 10 AV6 2 40 95 8 AV3 2 37 34 8 AV2 2 40 98 25 AV5 E-9
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 2 40 105 14 AV2 2 42 94 25 AV4 2 40 105 11 AV3 2 42 94 14 AV5 2 40 105 26 AV5 2 42 95 10 AV2 2 41 33 26 AV4 2 42 96 13 AV2 2 41 33 23 AV5 2 42 96 14 AV3 2 41 39 9 AV3 2 42 96 18 AV4 2 41 39 14 AV4 2 42 96 16 AV5 2 41 42 17 AV2 2 42 97 12 AV2 2 41 42 9 AV3 2 42 97 23 AV3 2 41 42 28 AV4 2 42 97 36 AV4 2 41 42 33 AV5 2 42 97 12 AV5 2 41 92 10 AV6 2 42 100 19 AV3 2 41 100 10 AV3 2 42 100 23 AV4 2 41 100 17 AV5 2 42 101 10 AV2 2 41 103 26 AV5 2 42 101 18 AV4 2 42 56 9 AV2 2 42 101 16 AV5 2 42 66 12 AV3 2 43 63 18 AV4 2 42 72 17 AV2 2 43 68 14 AV3 2 42 72 19 AV3 2 43 68 15 AV5 2 42 72 11 AV5 2 43 81 9 AV5 2 42 76 7 AV1 2 43 84 13 AV3 2 42 76 29 AV2 2 43 84 15 AV5 2 42 76 20 AV3 2 43 87 13 AV2 2 42 76 20 AV4 2 43 87 17 AV3 2 42 76 37 AV5 2 43 87 10 AV4 2 42 76 19 AV6 2 43 87 21 AV5 2 42 84 14 AV3 2 43 88 11 AV2 2 42 84 10 AV4 2 43 88 19 AV3 2 42 84 15 AV5 2 43 88 19 AV5 2 42 86 15 AV3 2 43 91 29 AV2 2 42 87 10 AV2 2 43 91 18 AV3 2 42 87 10 AV4 2 43 91 9 AV4 2 42 88 20 AV4 2 43 91 27 AV5 2 42 91 10 AV2 2 43 91 13 AV6 2 42 91 17 AV4 2 43 93 14 AV2 2 42 92 11 AV3 2 43 93 20 AV3 2 42 92 16 AV4 2 43 93 20 AV4 2 42 92 15 AV5 2 43 93 13 AV5 2 42 92 10 AV6 2 43 94 10 AV2 2 42 94 20 AV3 2 43 94 11 AV3 E-10
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 2 43 94 10 AV4 2 49 89 10 AV6 2 43 94 10 AV5 2 49 91 8 AV5 2 43 95 15 AV4 2 50 83 13 AV2 2 43 95 14 AV5 2 50 83 10 AV3 2 43 95 11 AV6 2 50 84 13 AV2 2 43 96 10 AV3 2 50 84 31 AV3 2 43 96 13 AV5 2 50 84 35 AV4 2 44 96 8 AV5 2 50 84 13 AV5 2 44 100 9 AV4 2 50 89 18 AV2 2 45 94 9 AV3 2 50 89 16 AV3 2 46 49 11 AV2 2 50 89 34 AV4 2 46 49 24 AV3 2 50 92 15 AV2 2 46 49 20 AV4 2 50 92 20 AV3 2 46 50 27 AV1 2 50 92 11 AV4 2 46 50 37 AV2 2 51 81 13 AV2 2 46 50 32 AV3 2 51 81 13 AV4 2 46 50 33 AV4 2 52 79 7 AV4 2 46 50 25 AV5 2 52 91 19 AV2 2 46 50 14 AV6 2 52 91 10 AV5 2 46 53 13 AV5 2 53 61 9 AV5 2 46 53 11 AV6 2 53 79 15 AV2 2 46 58 28 AV2 2 53 79 21 AV3 2 46 58 10 AV3 2 53 87 12 AV5 2 46 58 13 AV4 2 54 36 9 AV2 2 46 58 14 AV5 2 54 75 11 AV5 2 46 94 9 AV4 2 54 84 9 AV2 2 46 96 12 AV2 2 54 84 24 AV3 2 46 98 11 AV5 2 54 84 22 AV4 2 47 90 8 AV3 2 54 84 32 AV5 2 48 86 14 AV4 2 54 84 13 AV6 2 48 86 11 AV5 2 55 83 18 AV5 2 48 94 10 AV5 2 55 84 22 AV5 2 48 98 15 AV4 2 56 72 9 AV2 2 48 98 20 AV5 2 56 72 10 AV3 2 48 98 23 AV6 2 57 72 9 AV1 2 49 89 12 AV3 2 57 79 11 AV4 2 49 89 22 AV4 2 57 79 14 AV5 2 49 89 21 AV5 1% TWD-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-20-1086 1R22 Steam Generator Tube Inspection Report Table 5: Vogtle 1R22 SG3 AVB Wear Indications SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 3 25 115 8 AV2 3 39 17 10 AV1 3 25 115 10 AV5 3 39 17 13 AV2 3 28 8 14 AV1 3 39 17 29 AV3 3 28 8 20 AV6 3 39 17 24 AV4 3 28 51 6 AV5 3 39 17 10 AV5 3 30 10 10 AV2 3 39 17 31 AV6 3 30 10 10 AV5 3 39 20 10 AV4 3 32 52 7 AV1 3 39 21 13 AV2 3 34 110 12 AV4 3 39 21 14 AV5 3 35 16 12 AV1 3 39 21 13 AV6 3 35 16 20 AV3 3 39 26 34 AV2 3 35 16 14 AV4 3 39 26 14 AV5 3 35 16 11 AV5 3 39 29 16 AV2 3 36 13 12 AV5 3 39 32 9 AV3 3 36 29 7 AV2 3 39 35 11 AV2 3 36 34 9 AV2 3 39 35 27 AV3 3 36 34 12 AV5 3 39 35 19 AV4 3 36 34 10 AV6 3 39 35 13 AV5 3 36 44 10 AV2 3 39 48 7 AV4 3 36 44 11 AV5 3 39 51 10 AV3 3 37 106 10 AV6 3 39 57 6 AV2 3 37 107 17 AV1 3 39 62 7 AV4 3 37 107 11 AV4 3 39 63 15 AV3 3 37 107 12 AV5 3 39 63 8 AV5 3 37 108 10 AV1 3 39 66 15 AV3 3 37 108 11 AV2 3 39 66 13 AV4 3 37 108 13 AV6 3 39 66 17 AV5 3 38 17 12 AV6 3 39 67 11 AV3 3 38 34 9 AV2 3 39 67 12 AV4 3 38 34 12 AV4 3 39 74 11 AV4 3 38 34 8 AV5 3 39 82 8 AV5 3 38 35 12 AV5 3 39 102 20 AV2 3 38 69 10 AV3 3 39 102 30 AV5 3 38 89 11 AV3 3 40 18 6 AV3 3 38 106 17 AV3 3 40 18 8 AV4 3 38 106 12 AV5 3 40 18 9 AV6 3 38 106 16 AV6 3 40 19 9 AV1 3 38 107 13 AV4 3 40 19 16 AV2 3 38 107 12 AV6 3 40 19 10 AV4 E-12
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 3 40 19 19 AV5 3 41 99 12 AV4 3 40 19 13 AV6 3 41 99 30 AV5 3 40 30 23 AV5 3 41 100 13 AV2 3 40 30 11 AV6 3 41 100 12 AV4 3 40 35 13 AV4 3 41 102 29 AV2 3 40 38 10 AV6 3 41 102 36 AV3 3 40 41 8 AV3 3 41 102 33 AV4 3 40 91 10 AV3 3 41 102 16 AV5 3 40 96 9 AV3 3 41 102 11 AV6 3 40 97 15 AV3 3 41 103 12 AV5 3 40 97 11 AV4 3 41 103 10 AV6 3 40 98 15 AV2 3 41 104 14 AV2 3 40 98 7 AV3 3 41 104 13 AV4 3 40 98 10 AV4 3 42 21 17 AV2 3 40 100 21 AV2 3 42 21 16 AV3 3 40 100 10 AV4 3 42 21 17 AV4 3 40 100 15 AV5 3 42 21 20 AV5 3 40 101 12 AV2 3 42 22 8 AV2 3 40 101 11 AV5 3 42 22 7 AV4 3 40 102 29 AV2 3 42 22 10 AV5 3 40 102 13 AV6 3 42 22 9 AV6 3 40 104 15 AV2 3 42 23 6 AV2 3 40 104 20 AV4 3 42 23 10 AV3 3 40 104 11 AV5 3 42 23 30 AV4 3 40 104 21 AV6 3 42 23 14 AV5 3 40 105 15 AV6 3 42 25 13 AV4 3 40 106 15 AV6 3 42 25 8 AV5 3 41 19 14 AV3 3 42 26 20 AV4 3 41 19 19 AV4 3 42 26 19 AV5 3 41 19 33 AV5 3 42 27 15 AV2 3 41 19 11 AV6 3 42 27 10 AV4 3 41 20 17 AV4 3 42 27 28 AV5 3 41 20 16 AV5 3 42 28 13 AV2 3 41 21 22 AV4 3 42 28 10 AV3 3 41 21 16 AV5 3 42 28 11 AV4 3 41 24 9 AV3 3 42 28 11 AV5 3 41 89 12 AV5 3 42 28 8 AV6 3 41 97 10 AV4 3 42 29 8 AV3 3 41 99 12 AV3 3 42 29 14 AV4 E-13
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 3 42 29 9 AV5 3 45 48 22 AV5 3 42 35 27 AV4 3 45 48 6 AV6 3 42 35 19 AV5 3 45 49 24 AV2 3 42 38 10 AV6 3 45 49 28 AV3 3 42 43 17 AV2 3 45 61 14 AV3 3 42 43 15 AV5 3 45 61 19 AV4 3 42 43 7 AV6 3 45 61 23 AV5 3 42 48 10 AV3 3 45 64 22 AV3 3 42 50 7 AV1 3 45 67 22 AV3 3 42 50 30 AV2 3 45 67 24 AV4 3 42 50 19 AV3 3 45 69 15 AV2 3 42 50 37 AV4 3 45 69 12 AV3 3 42 50 9 AV5 3 45 69 15 AV5 3 42 58 6 AV2 3 45 77 14 AV2 3 42 58 16 AV3 3 45 77 11 AV3 3 42 63 22 AV4 3 45 77 9 AV4 3 42 66 12 AV3 3 45 82 21 AV3 3 42 66 17 AV4 3 45 82 19 AV4 3 42 67 11 AV3 3 45 100 12 AV5 3 42 67 9 AV5 3 46 24 13 AV4 3 42 102 11 AV4 3 46 25 8 AV3 3 42 102 11 AV6 3 46 25 11 AV4 3 44 22 9 AV3 3 46 25 15 AV5 3 44 22 8 AV4 3 46 25 9 AV6 3 44 22 15 AV5 3 47 26 16 AV5 3 44 26 31 AV2 3 47 30 13 AV5 3 44 97 10 AV4 3 47 35 10 AV2 3 44 102 10 AV4 3 47 35 15 AV4 3 45 22 9 AV5 3 47 38 21 AV2 3 45 40 17 AV3 3 47 38 27 AV4 3 45 40 16 AV4 3 47 38 11 AV5 3 45 40 15 AV5 3 47 45 10 AV2 3 45 40 8 AV6 3 47 45 24 AV4 3 45 46 13 AV1 3 47 56 7 AV3 3 45 46 35 AV2 3 47 95 8 AV6 3 45 46 34 AV3 3 47 96 25 AV4 3 45 46 23 AV4 3 47 96 13 AV6 3 45 46 16 AV5 3 48 25 8 AV6 3 45 48 21 AV2 3 48 26 12 AV2 3 45 48 29 AV3 3 48 26 14 AV6 E-14
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 3 48 27 7 AV2 3 51 55 12 AV3 3 49 34 26 AV4 3 51 55 16 AV4 3 49 34 11 AV5 3 51 55 9 AV5 3 49 34 10 AV6 3 51 92 10 AV6 3 49 92 9 AV4 3 53 84 19 AV3 3 49 92 12 AV5 3 53 84 37 AV4 3 49 93 12 AV6 3 53 84 16 AV5 3 49 96 9 AV4 3 54 88 6 AV1 3 49 96 11 AV5 3 54 88 8 AV6 3 49 96 33 AV6 3 57 53 12 AV6 3 50 33 10 AV3 3 58 50 13 AV6 3 50 33 11 AV4 3 58 51 13 AV6 3 50 33 11 AV5 3 58 52 15 AV6 3 50 83 17 AV5 3 58 60 11 AV4 3 50 86 12 AV2 3 58 61 11 AV1 3 50 86 8 AV3 3 59 61 12 AV4 3 50 86 17 AV5 3 59 63 13 AV6 3 50 93 10 AV6 3 59 68 13 AV6 1% TWD-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-20-1086 1R22 Steam Generator Tube Inspection Report Table 6: Vogtle 1R22 SG4 AVB Wear Indications SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 4 27 8 11 AV1 4 33 108 10 AV3 4 27 8 17 AV6 4 33 110 19 AV3 4 27 9 17 AV5 4 33 110 11 AV5 4 27 43 8 AV5 4 33 110 8 AV6 4 27 51 11 AV2 4 33 111 20 AV3 4 28 40 16 AV5 4 33 111 22 AV4 4 28 65 9 AV5 4 33 111 19 AV6 4 28 82 9 AV2 4 34 15 8 AV5 4 28 82 11 AV5 4 36 13 7 AV1 4 30 9 16 AV2 4 36 13 7 AV2 4 30 9 32 AV5 4 36 14 8 AV1 4 30 9 6 AV6 4 36 39 21 AV3 4 30 20 8 AV2 4 36 79 17 AV4 4 30 40 12 AV2 4 36 104 11 AV2 4 30 40 16 AV5 4 36 104 9 AV3 4 30 40 9 AV6 4 36 104 7 AV5 4 30 85 8 AV2 4 36 105 9 AV2 4 30 113 11 AV5 4 36 105 13 AV5 4 30 114 30 AV5 4 36 105 10 AV6 4 31 111 8 AV1 4 36 106 7 AV5 4 31 111 13 AV2 4 36 106 9 AV6 4 32 106 13 AV3 4 36 107 10 AV3 4 32 106 10 AV5 4 36 109 10 AV3 4 32 107 11 AV2 4 37 80 7 AV4 4 32 110 10 AV3 4 37 107 17 AV3 4 32 111 9 AV1 4 37 107 12 AV5 4 32 111 14 AV3 4 38 19 8 AV5 4 32 111 9 AV4 4 38 35 8 AV2 4 33 12 12 AV2 4 38 52 6 AV3 4 33 12 10 AV3 4 38 52 10 AV4 4 33 12 5 AV4 4 38 55 8 AV4 4 33 12 10 AV6 4 38 74 6 AV2 4 33 34 10 AV3 4 38 76 15 AV3 4 33 34 10 AV4 4 38 76 17 AV4 4 33 34 9 AV5 4 38 76 8 AV6 4 33 91 7 AV2 4 38 78 10 AV5 4 33 91 9 AV4 4 38 86 12 AV4 4 33 107 12 AV3 4 38 96 17 AV2 4 33 107 14 AV5 4 38 96 9 AV4 E-16
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 4 38 96 10 AV5 4 40 82 12 AV2 4 38 103 13 AV4 4 40 82 26 AV3 4 38 103 11 AV5 4 40 82 39 AV4 4 38 104 8 AV3 4 40 82 21 AV5 4 38 104 20 AV4 4 40 84 14 AV2 4 38 104 12 AV5 4 40 84 12 AV5 4 38 108 16 AV4 4 40 86 11 AV4 4 39 37 10 AV2 4 40 86 8 AV5 4 39 37 10 AV3 4 40 87 16 AV4 4 39 51 13 AV4 4 40 87 18 AV5 4 39 51 11 AV5 4 40 88 15 AV3 4 39 51 15 AV6 4 40 88 22 AV4 4 39 56 12 AV2 4 40 88 15 AV5 4 39 56 17 AV3 4 40 88 12 AV6 4 39 56 14 AV4 4 40 90 9 AV3 4 39 58 10 AV2 4 40 90 15 AV4 4 39 58 12 AV3 4 40 90 7 AV5 4 39 58 23 AV4 4 40 92 9 AV3 4 39 58 12 AV6 4 40 92 15 AV5 4 39 75 16 AV5 4 40 93 18 AV2 4 39 78 9 AV5 4 40 93 13 AV5 4 39 92 10 AV3 4 40 95 13 AV2 4 39 95 10 AV2 4 40 95 13 AV3 4 39 95 12 AV4 4 40 95 26 AV4 4 39 99 10 AV5 4 40 95 12 AV5 4 39 107 10 AV3 4 40 99 10 AV5 4 40 24 13 AV5 4 40 100 12 AV2 4 40 25 7 AV3 4 40 100 8 AV3 4 40 29 12 AV2 4 40 100 10 AV4 4 40 39 16 AV3 4 40 100 9 AV5 4 40 56 16 AV3 4 40 100 10 AV6 4 40 62 23 AV2 4 40 105 11 AV2 4 40 62 30 AV3 4 40 105 20 AV4 4 40 62 24 AV4 4 40 105 20 AV5 4 40 62 10 AV5 4 40 106 12 AV2 4 40 78 17 AV2 4 40 106 22 AV3 4 40 78 15 AV3 4 40 106 20 AV4 4 40 78 10 AV5 4 40 106 28 AV5 4 40 80 9 AV3 4 40 106 12 AV6 4 40 80 9 AV5 4 41 23 9 AV2 E-17
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 4 41 97 14 AV5 4 45 101 8 AV5 4 41 99 14 AV5 4 45 101 10 AV5 4 41 105 9 AV3 4 48 97 11 AV6 4 42 20 10 AV6 4 49 95 8 AV3 4 42 100 16 AV2 4 49 95 10 AV5 4 42 100 15 AV3 4 50 63 13 AV2 4 42 100 18 AV4 4 50 63 24 AV3 4 42 100 9 AV5 4 50 63 12 AV4 4 42 100 9 AV6 4 50 63 10 AV5 4 42 101 18 AV3 4 50 76 17 AV2 4 42 101 25 AV4 4 50 76 18 AV3 4 42 101 30 AV5 4 50 76 16 AV4 4 42 104 9 AV1 4 50 76 33 AV5 4 42 104 17 AV3 4 51 87 10 AV5 4 42 104 14 AV4 4 53 89 12 AV4 4 43 46 18 AV6 4 53 90 7 AV1 4 43 66 15 AV2 4 53 90 10 AV5 4 43 66 14 AV3 4 53 90 10 AV6 4 43 85 13 AV2 4 54 36 11 AV5 4 43 92 14 AV3 4 54 38 9 AV1 4 43 93 11 AV4 4 54 38 10 AV5 4 43 93 10 AV5 4 54 38 8 AV6 4 43 101 15 AV3 4 54 87 9 AV2 4 43 101 15 AV4 4 54 87 10 AV3 4 43 101 28 AV5 4 54 87 12 AV4 4 44 91 13 AV5 4 55 40 10 AV6 4 44 96 8 AV2 4 55 82 8 AV4 4 44 96 35 AV3 4 55 82 11 AV5 4 44 96 26 AV4 4 55 83 13 AV4 4 44 96 12 AV6 4 56 41 10 AV5 4 44 97 26 AV2 4 56 81 13 AV5 4 44 97 22 AV4 4 56 81 11 AV6 4 44 97 27 AV5 4 57 55 9 AV6 4 44 99 10 AV4 4 58 48 9 AV5 4 44 99 11 AV6 4 58 65 8 AV1 4 45 22 11 AV3 4 58 73 12 AV6 4 45 22 9 AV5 4 58 74 14 AV6 4 45 98 21 AV5 4 58 76 15 AV5 4 45 101 10 AV1 4 59 55 13 AV2 E-18
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report SG Row Column % TWD1 Location2 SG Row Column %TWD1 Location2 4 59 57 14 AV5 4 59 59 13 AV5 I4 I 59 1%
I 59 9 AV2 2
11 TWD-Percent Through-wall Depth AV# Location of AVB intersection with the tube (there are up to 6)
Mechanical Wear and Wall Loss from Secondary Side Cleaning Processes Table 7 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 1R22, the largest indication of mechanical wear and wall loss from secondary side cleaning measured 39% TW. This is much smaller than the 48% TW condition monitoring limit at 3PNO 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 1R22 inspection for degradation associated with indications of wear and wall loss from secondary side cleaning processes.
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Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report Table 7: Vogtle 1R22 Tube Wall Loss from Secondary Cleaning Process SG Row Column Indication %TWD Location 1 1 83 PCT 10 TSH+18.44 1 1 87 PCT 39 TSH+19.97 1 58 70 PCT 23 BPH+0.42 2 1 70 PCT 5 TSC+11.39 2 1 70 PCT 9 TSC+9.74 2 1 70 PCT 7 TSC+8.48 2 1 78 PCT 8 TSC+9.36 2 1 78 PCT 5 TSC+8.1 2 1 82 PCT 4 TSC+8.98 2 16 6 PCT 11 BPC+0.63 2 16 7 PCT 28 BPC+0.58 2 1 91 PCT DSS1 BPC-0.38 2 10 101 PCT NDD2 BPH-0.19 1
DSS - Distorted Support Signal.
2 NDD - No Degradation Detected.
%TWDPercent Throughwall Depth BPHBaffle Plate on the HL side PCT Volumetric Indication TSCTubesheet Region on the CL side TSHTubesheet Region on the HL Side BPCBaffle Plate on the CL side Mechanical Wear at Tube Support Plate 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. Mechanical wear at the tube support plate was first identified during the 1R21 inspection when two wear indications were reported. The two previous indications of wear at broached tube support plate intersections were identified in 1R22.
During 1R22, the largest indication of mechanical wear at tube support plates measured 19%
TW. This is much smaller than the 53% TW condition monitoring limit at 3PNO and satisfies the SG structural performance criteria.
Table 8: Vogtle 1R22 Wear at Tube Support Plate Locations SG Row Column Indication %TWD Location 1 20 53 PCT 5 5H-0.63 4 44 21 PCT 19 7H-0.45 5H Tube Support Plate 5 on HL side 7H Tube Support Plate 7 on HL side E-20
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report 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 1R22 eddy current inspection scope development in accordance with the guidelines. During 1R22, there were two circumferential ODSCC indications reported. One indication was contained in SG1 Tube R7C20 at TSH-0.46 inch below the top of the tubesheet. The second indication was contained in SG2 Tube R16C61 at TSH-0.06 inch below the top of the tubesheet. Both indications were well within the condition monitoring limit of 54 PDA and critical crack length of 194 degrees. The burst and ligament tearing of the most limiting flaw (R7C20 in SG1) are 7836 psi and 7552 psi. These are above the minimum burst and leakage integrity limits of 4044 psi and 2560, respectively. Condition monitoring requirements have been satisfied at the 1R22 inspection for degradation associated with ODSCC at the hot leg expansion transitions.
There were no axial ODSCC indications identified during 1R22.
Table 9 provides a listing of the indications reported with their associated depth and extents.
Table 9: Vogtle 1R22 Circumferential ODSCC at Expansion Transitions Location Circ Ext. Percent Max (deg) Degraded SG Row Col Volts Indication Depth Area
%TWD (PDA) 1 7 20 0.10 SCI TSH-0.46 63 40 6.2 2 16 61 0.11 SCI TSH-0.06 36 36 2.9 SCI - Single Circumferential Indication
%TWDPercent Throughwall Depth 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 1R22. Therefore, condition monitoring requirements have been satisfied at the 1R22 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 1R22, no indications of PWSCC were reported.
Therefore, condition monitoring requirements have been satisfied at the 1R22 inspection for this degradation.
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Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report PWSCC at Hot Leg Expansion Transitions Axial PWSCC at hot leg tubesheet expansion transitions was first identified during the 1R20 inspection. There were no PWSCC indications reported from Hot Leg Expansion Transitions from +POINT probe analyses during 1R22. Therefore, condition monitoring requirements have been satisfied at the 1R22 inspection for degradation associated with PWSCC at the Hot Leg Expansion Transitions.
Tube Plugging/Number of Tubes Plugged Table 10 presents a summary list of all SG tubes plugged in 1R22 and the related degradation mechanism. Table 11 provides the total plugged tubes after 1R22 for Vogtle 1.
Table 10: Vogtle 1R22 Plugging List SG Row Column Indication Location Plugging Stabilizer Degradation Basis Mechanism 1 7 20 SCI TSH-0.46 Circ. Yes - HL Circ.
ODSCC TTS ODSCC at Tubesheet Expansion Transitions 1 23 28 VOL TSH+0.4 Preventative No Foreign Object Wear 2 16 61 SCI TSH-0.06 Circ. Yes - HL Circ.
ODSCC TTS ODSCC at Tubesheet Expansion Transitions 2 39 103 PCT AV5+0 AVB Wear No AVB Wear 41% TW SCI - Single Circumferential Indication HL TTS - Hot Leg Top of Tubesheet E-22
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report Table 11: Total Plugged Tubes after Vogtle 1R22 SG #Tubes 1R22 Total % Plugging
- Plugged # Plugged 1 5,626 2 31 0.55%
2 5,626 2 30 0.53%
3 5,626 0 40 0.71%
4 5,626 0 82 1.46%
Total 22,504 4 183 0.81%
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. All four SGs showed no tube severance indications reported; therefore, no indications of slippage were identified.
None of the indications reported during the Vogtle 1R22 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 1R22, visual inspections 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 1R22 and showed no discernable changes in shape or size. No other channel head degradation was observed in any SGs during 1R22.
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 E-23
Enclosure to NL-20-1086 1R22 Steam Generator Tube Inspection Report secondary leakage prior to the end of the Vogtle 1 SG inspection interval. 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 1R22 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 24 without exceeding the performance criteria. Based on worst-case flaw projection, operation until the end of 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. 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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