Vogtle, Unit 1 - Eighteenth Maintenance/Refueling …Regulatory Affairs Director Operating Company,...

Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35201

October 3, 2014

Tel 205.992.7872 Fax 205.992.7601 SOUT RN «\

COM aNY

Docket Nos.: 50-424 NL-14-1520

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001

Vogtle Electric Generating Plant- Unit 1 Eighteenth Maintenance/Refueling Outage 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 this report of the steam generator tube inspections performed during the Unit 1 eighteenth maintenance/refueling outage (1 R18). Entry into Mode 4 occurred on April 7, 2014.

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

Respectfully submitted,

C. fl.~ C. R. Pierce Regulatory Affairs Director

CRP/GLS/Iac

Enclosure: 1 R18 Steam Generator Tube Inspection Report

cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, Executive Vice President & Chief Nuclear Officer Mr. D. R. Madison, Vice President- Vogtle 1 & 2 Mr. B. L. lvey, Vice President- Regulatory Affairs Mr. B. J. Adams, Vice President- Engineering Mr. T. E. Tynan , Vice President- Fleet Operations Mr. G. W. Gunn, Regulatory Affairs Manager- Vogtle 1 & 2 (Acting) RType: CVC7000

U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager- Vogtle 1 & 2 Mr. L. M. Cain, Senior Resident Inspector- Vogtle 1 & 2

Vogtle Electric Generating Plant- Unit 1 Eighteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report

Enclosure

1 R18 Steam Generator Tube Inspection Report

Enclosure

Vogtle Electric Generating Plant- Unit 1 1 R18 Steam Generator Tube Inspection Report

Introduction

The Vogtle 1 R18 outage was conducted after cumulative steam generator (SG) service equivalent to approximately 24 effective full power years (EFPY); the Cycle 18 power generation was approximately 1.4 EFPY. Analyses, based on conservative assumptions used in the Condition Monitoring and Operational Assessments, demonstrated that there were no tubes that exceeded the Regulatory Guide 1.121 or NEI-97-06 Revision 3 criteria for tube integrity during Cycle 18. 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). Ten tubes were plugged in Steam Generator 4. One tube (R49C54) was plugged due to 40% through wall (TW) wear at anti-vibration bar 3 (AVB3) that met the Technical Specifications (TS) plugging criteria. One tube (R11 C75) was stabilized and plugged due to a primary water stress corrosion crack (PWSCC) indication at a tubesheet expansion bulge. Eight tubes were stabilized and plugged due to outer diameter stress corrosion crack (ODSCC) indications at the hot leg top of tubesheet tube expansion transition region. None of the indications exceeded the condition monitoring limits identified in the Degradation Assessment and therefore did not require in situ proof of pressure testing to demonstrate tube integrity. Permanent H* Alternate Repair Criteria has been approved by the NRC for implementation (Reference ADAMS Accession Number ML 12216A056). Therefore, tube end +Point inspections below top of tubesheet (TTS)-15.2 inches were omitted, and the TTS inspections ranged from TTS +3 inches to TTS -15.2 inches.

1R18 Scope

The scope for 1 R18 involved the scheduled inspections listed below. The inspection program, required by Revision 7 of the Electric Power Research Institute (EPRI) Pressurized Water Reactor (PWR) SG Examination Guidelines, addressed the known degradation mechanisms observed in Vogtle Unit 1 in prior inspections, as well as those regarded as potential degradation mechanisms.

• 1 00% Bobbin examination of tubes in SGs 1 and 4, full length except for Rows 1 and 2, which were inspected from the tube end to the top tube support plate (TSP) from both hot leg (HL) and cold leg (CL).

• 1 00% +Point examination of Row 1 and 2 U-bends from the top TSP on the HL to the top TSP on the CL in all SGs.

• +Point examination of Special Interest of bobbin possible flaw locations including UBends in both the HL and CL.

• 100% +Point examination of HL tubes in all SGs from the TTS to the licensed ARC depth for H* (TSH +3/-15.2 inches). This inspection captured 100% of the TTS and BLG/OXP populations, as defined below, along with the periodic sample that comes with regulatory approval of the Permanent Alternate Repair Criteria.

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

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Enclosure

Vogtle Electric Generating Plant - Unit 1 1 R 18 Steam Generator Tube Inspection Report

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

• 25% +Point examination of dents (DNT) and dings (DNG) ~ 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. Verification has been made that 100% of the HL straight length and U-bend dent and ding locations~ 2 volts have been +Point tested in all SGs since 1 R15 in the fall of 2009.

• 1 00% visual inspection of tube plugs.

• Visual inspection of all SGs channel head on HL and CL side inclusive of the divider plate to channel head weld and all visible clad surfaces.

No Secondary Side work was performed during 1 R18.

Damage Mechanisms Found and NDE Techniques Utilized

All of the damage mechanisms found during the 1 R18 inspections were identified in previous inspections and in the 1 R18 SG Degradation Assessment.

• Bobbin techniques were used to evaluate the following degradation mechanisms. o Mechanical Wear at AVB Supports. o Mechanical Wear and Wall loss from secondary side cleaning processes.

• +Point techniques were used to evaluate the following degradation mechanisms. o Mechanical Wear due to Foreign Objects. o ODSCC at the hot Leg expansion transitions. o PWSCC at tube bulge and overexpansion locations.

Service Induce Indication Descriptions

Foreign Objects Wear

Foreign object wear, while not affecting a large population of tubes, is an existing degradation mechanism in a majority of operating SGs including those at Vogtle Unit 1. Foreign objects have also been reported as the cause for tube wear at Vogtle Unit 1 in prior inspections. Therefore, wear due to foreign objects is classified as an existing degradation mechanism and has been addressed in the SG inspection plan for 1 R18. Table 1 lists the data record for the eddy current signals corresponding to a possible loose part (PLP) or a foreign object wear indication. All PLP signals in Table 1 are historical, have been visually inspected during prior outages, show no significant change in eddy current signal response and therefore did not require a secondary side inspection during 1 R18. Additionally, no new foreign object wear associated with known foreign objects in the SG secondary side was observed.

The Percent Code (PCT) indications in SG1 tube rows 24, 39 and 41 have been present for several cycles with no apparent growth or change in character outside of NDE measurement uncertainties. A new wear indication measuring 24% TW has been reported in SG1 at tube R55C82. A +Point expansion of at least two tubes in all directions, including all tubes out to the tube bundle periphery, was performed at the baffle plate and identified an additional4% TW indication on tube R56C82. No foreign object was identified adjacent to any of the tubes

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Enclosure

Vogtle Electric Generating Plant - Unit 1 1 R18 Steam Generator Tube Inspection Report

examined in this region. Although a majority of the indications in Table 1 are located in SG1, both the PLPs and PCT wear indications are mainly historical in nature and it is judged that this SG is no more likely than any of the others to be affected by foreign objects during future operation. The PCT indications in SG2 and SG3 listed in Table 1 show no change outside of NDE measurement uncertainties. The indications in SG4 have been present in history with no change in eddy current response for at least two cycles of operation. A history review was performed on SG4 tube locations R40C57 and R49C89, these locations exhibited similar bobbin response signals during the 1 R 16 inspections and were conservatively assigned a % TW at 1 R 18. Based on the inspection data, Condition Monitoring assessment has been met at the 1 R18 inspection for the degradation associated with foreign objects.

Table 1 Vogtle 1R18 PLP/Foreign Object Wear Indications

SG Row Column 1 25 8 1 25 9 1 36 87 1 36 88 1 14 112 1 15 112 1 24 66 1 55 82 1 56 82 1 41 97 1 39 100 1 41 100 1 41 100 1 41 101 1 41 102 1 41 103 2 18 8 2 19 8 2 50 35 2 51 35 2 35 106 2 36 106 2 6 1 3 30 111 4 30 18 4 31 18 4 40 57 4 49 89 4 38 104

1 % TWD- Percent Through-Wall Depth 2 PLP - Possible Loose Part 3 TSH - Tubesheet region on HL side

Indication PLP2

PLP PLP PLP PLP PLP PCT4

PCT PCT PCT PCT PCT PCT PCT PCT PCT PLP PLP PLP PLP PLP PLP PCT PCT PLP PLP PCT PCT PCT

4 PCT- Volumetric Indication Foreign Object Wear 5 3C - Tube Support Plate 3 on the Cold Leg side 6 BPH - Flow Distribution Baffle Plate on the Hot Leg side

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%TWD1

------9 24 4 24 12 15 29 22 22 22 ------7 33 --9 10 14

Location TSH3

TSH TSH TSH TSH TSH 3C!)

BPH6

BPH TSC7

TSH TSH TSH TSH TSH TSH TSH TSH TSH TSH TSH TSH 1C8

BPH TSH TSH 6H!:I BPH BPH

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7 TSC- Tubesheet region on the Cold Leg side 8 1 C - Tube Support Plate 1 on the Cold Leg side 9 6H - Tube Support Plate 6 on the Hot Leg side

Mechanical Wear at AVB Supports

Anti-vibration bar (AVB) wear identified during Vogtle 1 R 18 in SG 1 and SG 4 is provided in Tables 3 and 4 below. All AVB wear locations have been examined in SG1 and SG4 and only one of the wear locations exceeded the technical specification plugging criteria of 40% TW. Table 2 below indicates the NDE character of the plugged tube location and the associated percent through-wall flaw measurement. The corresponding inspection of AVB wear locations in SG2 and SG3 was last performed during 1 R17 and assessed for operation through 1 R19. None of the indications observed exceeded the condition monitoring assessment limits for AVB wear identified in the degradation assessment. The maximum AVB wear indication reported during 1 R 18 was in SG4 at R49C54 AV3 measuring 40% TW. This indication is less than the maximum projected 49.3% TW depth for AVB wear indications at the end of Cycle 18 calculated in the Vogtle 1 R16 Condition Monitoring and Operational Assessment Report.

Table 2 Vogtle 1 R18 Pluggable AVB Wear Indications

SG Row Column Volts Location 4 49 54 . 2.25 AV3

1 %TWO - Percent Through-wall Depth 2 PCT- Volumetric Indication, anti-vibration bar wear

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Table 3 Vogtle 1 R18 AVB Wear Indications in SG 1

Row Column Indication %TWD1 Location2 Row Column Indication %TWD1 Location2

23 40 PCT3 10 AV6 40 34 PCT3 12 AV3 23 116 PCT 14 AV6 40 34 PCT 17 AV4 24 116 PCT 14 AV6 40 34 PCT 10 AV6 26 116 PCT 16 AV1 40 38 PCT 10 AV4 26 116 PCT 23 AV6 40 47 PCT 33 AV3 27 100 PCT 10 AVS 40 47 PCT 35 AV4 27 115 PCT 11 AV1 40 47 PCT 9 AVS 27 115 PCT 14 AV6 40 47 PCT 9 AV6 28 115 PCT 16 AV1 40 62 PCT 12 AV3 28 115 PCT 28 AV6 40 62 PCT 8 AVS 32 104 PCT 12 AV6 40 75 PCT 10 AV3 34 107 PCT 10 AV1 40 94 PCT 10 AV4 34 107 PCT 15 AV3 40 104 PCT 16 AV3 35 16 PCT 13 AV4 40 104 PCT 16 AV4 35 18 PCT 11 AV6 41 18 PCT 10 AV4 35 34 PCT 8 AV3 41 18 PCT 9 AVS 35 34 PCT 9 AV4 41 18 PCT 14 AV6 35 104 PCT 14 AV3 41 23 PCT 10 AV4 35 104 PCT 10 AV4 41 34 PCT 9 AV4 36 105 PCT 11 AV3 41 44 PCT 19 AV2 37 77 PCT 11 AV3 41 44 PCT 32 AV3 37 102 PCT 22 AVS 41 51 PCT 12 AV4 38 16 PCT 10 AV1 41 80 PCT 11 AV3 38 16 PCT 17 AV2 42 34 PCT 16 AV4 38 16 PCT 15 AV3 42 37 PCT 11 AV6 38 16 PCT 31 AV4 42 43 PCT 10 AV2 38 16 PCT 10 AVS 42 43 PCT 10 AV3 38 108 PCT 11 AV1 42 43 PCT 11 AV4 38 108 PCT 12 AV6 42 43 PCT 13 AVS 39 48 PCT 13 AV2 43 21 PCT 7 AV2 39 48 PCT 21 AV3 43 21 PCT 23 AV4 39 48 PCT 22 AV4 43 21 PCT 27 AVS 39 48 PCT 13 AVS 43 21 PCT 9 AV6

39 87 PCT 9 AV4 43 81 PCT 13 AV4

39 90 PCT 9 AV2 43 81 PCT 8 AVS

39 90 PCT 12 AV3 43 82 PCT 14 AV3

39 104 PCT 11 AV4 43 83 PCT 9 AVl

40 20 PCT 12 AV4 43 83 PCT 14 AV2

40 34 PCT 9 AV2 43 83 PCT 15 AV3

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Enclosure


Table 3 continued Vogtle 1R18 AVB Wear Indications in SG 1

Row Column Indication %TWD1 Location2 Row Column Indication %TWD1

43 83 PCT3 20 AV4 52 39 PCT3 27 43 83 PCT 13 AVS 52 39 PCT 11 43 85 PCT 10 AV2 52 44 PCT 22 43 91 PCT 30 AV2 52 91 PCT 12 43 91 PCT 17 AV3 53 39 PCT 9 43 91 PCT 14 AV4 53 43 PCT 6 44 21 PCT 15 AVS 53 43 PCT 7 44 80 PCT 8 AV3 53 87 PCT 10 44 80 PCT 11 AV4 53 90 PCT 16 44 80 PCT 10 AVS 54 36 PCT 10 44 102 PCT 13 AV2 54 37 PCT 12 45 26 PCT 12 AV3 54 37 PCT 11 45 30 PCT 13 AV3 54 45 PCT 7 45 36 PCT 9 AVS 54 53 PCT 11 45 90 PCT 16 AV2 54 83 PCT 11 45 90 PCT 10 AV3 54 83 PCT 11 46 41 PCT 8 AV1 57 45 PCT 21 47 99 PCT 11 AV2 57 45 PCT 35 48 97 PCT 11 AV1 57 45 PCT 9

49 88 PCT 9 AV4 57 45 PCT 11 so 29 PCT 11 AV1 57 78 PCT 14

so 29 PCT 9 AV2 58 75 PCT 13

52 33 PCT 17 AV2 58 76 PCT 12

52 33 PCT 17 AV3 59 62 PCT 10

52 39 PCT 21 AV2 52 39 PCT 30 AV3

1 %TWO -Percent Through-wall Depth 2 Location: AV# - Location of anti-vibration bar intersection with the tube (there are up to 6) 3 PCT- Volumetric Indication

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Location2

AV4 AVS AV4 AV1 AV6 AV2 AVS AV3 AV6 AV2 AV1 AV6 AV2 AV2 AV1 AV6 AV2 AV3 AVS AV6 AV6 AV1 AV6 AV6

Enclosure


Table 4 Vogtle 1R18 AVB Wear Indications in SG 4


27 8 PCT3 17 AV6 36 14 PCT3 10 AV1 27 9 PCT 17 AV5 36 39 PCT 23 AV3 27 43 PCT 10 AV5 36 79 PCT 18 AV4 27 51 PCT 10 AV2 36 104 PCT 14 AV2 28 40 PCT 17 AV5 36. 104 PCT 10 AV3 28 65 PCT 9 AV5 36 104 PCT 11 AV5 28 82 PCT 13 AV5 36 105 PCT 9 AV2 30 9 PCT 17 AV2 36 105 PCT 12 AV5 30 9 PCT 34 AV5 36 106 PCT 9 AV5 30 20 PCT 9 AV2 36 106 PCT 10 AV6 30 40 PCT 15 AV5 36 107 PCT 11 AV3 30 40 PCT 11 AV6 36 109 PCT 11 AV3 30 113 PCT 11 AV5 37 80 PCT 8 AV4 30 114 PCT 29 AV5 37 107 PCT 12 AV3 31 111 PCT 9 AV1 38 19 PCT 10 AV5 31 111 PCT 11 AV2 38 35 PCT 9 AV2 32 106 PCT 14 AV3 38 52 PCT 8 AV3 32 110 PCT 12 AV3 38 52 PCT 12 AV4 32 111 PCT 9 AV1 38 55 PCT 9 AV4 32 111 PCT 14 AV3 38 74 PCT 9 AV2 32 111 PCT 10 AV4 38 76 PCT 14 AV3 33 12 PCT 11 AV2 38 76 PCT 16 AV4 33 12 PCT 10 AV3 38 76 PCT 6 AV6 33 12 PCT 6 AV4 38 86 PCT 16 AV4 33 12 PCT 10 AV6 38 96 PCT 13 AV2 33 34 PCT 9 AV3 38 96 PCT 8 AV4 33 34 PCT 10 AV4 38 96 PCT 10 AV5 33 34 PCT 12 AV5 38 103 PCT 12 AV4 33 91 PCT 6 AV2 38 103 PCT 10 AV5 33 108 PCT 12 AV3 38 104 PCT 12 AV3 3,3 110 PCT 22 AV3 38 104 PCT 22 AV4 33 110 PCT 12 AV5 38 104 PCT 14 AV5 33 110 PCT 8 AV6 38 108 PCT 16 AV4 33 111 PCT 19 AV3 39 37 PCT 11 AV3 33 111 PCT 22 AV4 39 51 PCT 13 AV4 33 111 PCT 18 AV6 39 51 PCT 12 AV5 34 15 PCT 7 AV5 39 51 PCT 16 AV6 36 13 PCT 9 AV1 39 56 PCT 11 AV2 36 13 PCT 9 AV2 39 56 PCT 17 AV3

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Enclosure




39 56 PCT3 14 AV4 40 93 PCT3 14 AV5 39 58 PCT 11 AV2 40 95 PCT 12 AV2 39 58 PCT 22 AV4 40 95 PCT 13 AV3 39 58 PCT 16 AV6 40 95 PCT 27 AV4 39 75 PCT 17 AV5 40 95 PCT 13 AV5 39 78 PCT 11 AV5 40 100 PCT 14 AV2 39 107 PCT 12 AV3 40 100 PCT 8 AV3 40 24 PCT 15 AV5 40 100 PCT 11 AV4 40 25 PCT 12 AV3 40 100 PCT 10 AV5 40 29 PCT 12 AV2 40 100 PCT 12 AV6 40 39 PCT 15 AV3 40 105 PCT 10 AV2 40 56 PCT 17 AV3 40 105 PCT 19 AV4 40 62 PCT 28 AV2 40 105 PCT 20 AV5 40 62 PCT 35 AV3 40 106 PCT 17 AV3 40 62 PCT 27 AV4 40 106 PCT 20 AV4 40 62 PCT 12 AV5 40 106 PCT 28 AV5 40 78 PCT 18 AV2 41 23 PCT 10 AV2 40 78 PCT 17 AV3 41 97 PCT 13 AV5 40 78 PCT 10 AV5 41 99 PCT 12 AV5 40 82 PCT 12 AV2 41 105 PCT 9 AV3 40 82 PCT 23 AV3 42 20 PCT 12 AV6 40 82 PCT 34 AV4 42 100 PCT 17 AV2 40 82 PCT 19 AV5 42 100 PCT 14 AV3 40 84 PCT 15 AV2 42 100 PCT 18 AV4 40 84 PCT 9 AV5 42 100 PCT 12 AV6 40 86 PCT 13 AV4 42 101 PCT 17 AV3 40 86 PCT 10 AV5 42 101 PCT 23 AV4 40 87 PCT 18 AV4 42 101 PCT 26 AV5 40 87 PCT 20 AV5 42 104 PCT 18 AV3 40 88 PCT 14 AV3 42 104 PCT 14 AV4 40 88 PCT 20 AV4 43 46 PCT 20 AV6 40 88 PCT 15 AV5 43 66 PCT 16 AV2 40 88 PCT 13 AV6 43 66 PCT 15 AV3 40 90 PCT 8 AV3 43 85 PCT 13 AV2 40 90 PCT 15 AV4 43 92 PCT 13 AV3 40 90 PCT 9 AV5 43 93 PCT 10 AV4 40 92 PCT 10 AV3 43 101 PCT 15 AV4 40 92 PCT 14 AV5 43 101 PCT 26 AV5 40 93 PCT 15 AV2 44 91 PCT 15 AV5

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Enclosure



Row Column Indication %TWD1 Location2 Row Column Indication %TWD1

44 96 PCT3 9 AV2 50 76 PCT3 15 44 96 PCT 29 AV3 50 76 PCT 29 44 96 PCT 23 AV4 53 89 PCT 12 44 96 PCT 15 AV6 53 90 PCT 11

44 97 PCT 22 AV2 53 90 PCT 13

44 97 PCT 21 AV4 53 90 PCT 13

44 97 PCT 26 AV5 54 36 PCT 13

44 99 PCT 11 AV6 54 38 PCT 10 45 22 PCT 11 AV5 54 38 PCT 10 45 101 PCT 11 AV1 54 38 PCT 9 45 101 PCT 9 AV5 55 40 PCT 11 45 101 PCT 10 AV5 55 82 PCT 12 48 97 PCT 11 AV6 55 82 PCT 12 49 54 PCT 20 AV2 56 41 PCT 10 49 54 PCT 40 AV3 56 81 PCT 12

49 54 PCT 32 AV4 57 55 PCT 11

49 54 PCT 24 AV5 58 48 PCT 10

49 95 PCT 11 AV3 58 65 PCT 11

50 63 PCT 16 AV2 58 73 PCT 12

50 63 PCT 23 AV3 59 57 PCT 15

50 63 PCT 17 AV4 59 59 PCT 13

50 76 PCT 16 AV3

1 % TWD -Percent Through-wall Depth 2 Location: AV# - Location of anti-vibration bar intersection with the tube (there are up to 6) 3 PCT- Volumetric Indication

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Location2

AV4 AV5 AV4 AV1 AV5 AV6 AV5 AV1 AV5 AV6 AV6 AV4 AV5 AV5 AV6 AV6 AV5 AV1 AV6 AV5 AV2

Enclosure


Mechanical Wear and Wall Loss from Secondary Side Cleaning Process

The tube locations and volumetric indications associated with the ultrasonic energy cleaning (UEC) and pressure pulse cleaning (PPC) secondary side cleaning processes are listed in Table 5. The examinations required to be performed to address this existing degradation mechanism are an element of the bobbin inspection program which alternates two SGs each inspection. Since 100% bobbin inspection in SG1 and SG4 were scheduled, the tubes listed in these SGs were required to be examined during 1 R18. An examination of some indications in SG2 has been conservatively performed during 1 R 18.

During 1 R 13, the volumetric indications reported in Row 1 tubes in the cold leg of SG2 were also observed by visual inspection. They have been reported to visually resemble tube oxide removal patterns observed in qualification testing for UEC. No foreign objects have been determined to be associated with these tube wear indications. There tubes have been left in service for several inspection intervals with no indications of tube wall loss outside of ECT measurement uncertainties.

Percent Code (PCT) calls in SG1 on R1C83 and R1C87 are legacy remnants of the sludge monorail issues. The PCT call in SG1 at R58C70 is attributable to the PPC process and has been present as a volumetric defect as far back as 1 R8 and succeeding inspections suggest no growth outside of NDE measurement uncertainties. The baffle plate indications in SG2 have also been present at prior cycles with no significant growth. The SG2 indications in tubes R1 C91 and R1 OC1 01 will be tested as part of the bobbin and +Point programs during 1 R19. Based on the inspection data in comparison with the limits, Condition monitoring assessment has been met at the 1 R18 inspection for the degradation associated with wear and wall loss from the secondary side cleaning process.

Table 5 Vogtle 1 R18 Tube Wall Loss from Secondary Side Cleaning Process

SG Row Column 1 1 83 1 1 87 1 58 70 2 1 70 2 1 70 2 1 70 2 1 78 2 1 78 2 1 82 2 1 91 2 10 101 2 16 6 2 16 7

1% TWO - Percent Through-wall Depth 2PCT- Volumetric Indication

Volts 0.11 0.53 0.33 0.07 0.08 0.05 0.05 0.09 0.05 0.49 0.4 0.14 0.38

3TSH - Tubesheet Region on the Hot Leg Side_

Indication %TWD1 Location PCTZ 11 TSH3

PCT 37 TSH PCT 26 BPH4

PCT 7 TSC5

PCT 8 TSC PCT 5 TSC PCT 5 TSC PCT 9 TSC PCT 5 TSC PCT - BPC PCT - BPH PCT 13 BPC PCT 29 BPC

4BPH - Baffle Plate on the Hot Leg Side 5TSC - Tubesheet Region on the Cold Leg Side

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Enclosure


ODSCC at the Hot Leg Expansion Transitions

Experience of both axial and circumferential Outside Diameter Stress Corrosion Cracking (ODSCC) at the HL TIS expansion transitions has been broad for SGs with Alloy 600MA tube material and recently has been observed in several plants with Alloy 600TI tubing. ODSCC at the hot leg expansion transitions is an existing degradation mechanism for Vogtle Unit 1 and this experience has been considered in the Vogtle 1 R18 eddy current inspection scope development in accordance with the Steam Generator Management Program: EPRI Pressurized Water Reactor Steam Generator Examination Guidelines, Revision 7.

Table 61ists ODSCC signals reported at or near the top of the tubesheet from +Point analyses during 1 R18. The maximum voltage for each of these flaws is less than the initial 0.5 Volt screen for structural integrity and the 1.01 Volt screen for leakage integrity in accordance with the Steam Generator Management Program: EPRI Steam Generator In Situ Pressure Test Guideline, Revision 4, indicating that condition monitoring has been met. As a measure of conservatism, NDE profiling was performed in the field for three of the indications and the rest were profiled following the outage. In addition, these flaws are consistent in character with those observed in prior inspections including that of the tube pulled from SG4 HL location R12C98. The laboratory examinations showed that this tube had a circumferential ODSCC flaw at the HL expansion transition of greater significance than those observed during 1 R18. Laboratory destructive burst and leakage testing of the R12C98 flaw indicated that the performance criteria were met with measurable margin. Therefore, based on both laboratory and collected NDE data in comparison with the limits, condition monitoring assessment has been met at the 1 R18 inspection for ODSCC at the hot leg expansion transition.

Table 6 Vogtle 1 R18 HL TIS Expansion Transition Indications

SG Row Column

4 9 106 4 6 108 4 8 109 4 6 111 4 9 111 4 7 112 4 6 113 4 4 116

1SCI- Single Circumferential Indication 2MCI- Multiple Circumferential Indication

Indication Crack Angle (Degrees)

scP 87 MCI2 58 SCI 120 SCI 118 MCI 129 SCI 87 SCI 102 SCI 121

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Max Depth Stabilized? (%) 40 Yes 72 Yes 40 Yes 44 Yes 40 Yes 59 Yes 42 Yes 40 Yes

Enclosure


PWSCC at Tube Bulge and Overexpansion Locations

Primary water stress corrosion cracking (PWSCC) indications related to profile changes resulting from tube expansion performed to seal the tubesheet crevice during SG assembly has been observed in hydraulically expanded Alloy 600TT tubing. PWSCC in tubesheet joint profile anomalies, such as bulges (BLGs) and over expansions (OXPs), is an existing degradation mechanism in the Vogtle Unit 1 SGs. This mechanism was last observed in 1 R12 and a single new indication has been identified in the 1 R18 inspection. Table 7 lists the signal reported at a tubesheet BLG from +Point analyses.

The bulge associated with the SG4 R 11 C75 PWSCC indication measured 198 Volts and is among the most substantial in all four SGs. Sizing of the indication shows an angular extent of 26 degrees which is significantly less than the structural limit of 265 degrees for a 1 00% through-wall crack. The indication is also restrained within the tubesheet which precludes a structural burst. A 26 degree circumferential crack presents negligible potential for exceeding the leakage-based performance criteria. This is confirmed by evaluating the R11 C75 indication maximum voltage of 0.42 volts against the threshold voltage of 0.97 volts for leak testing of circumferentiaiiD cracks. No measureable primary to secondary leakage was identified during the current operating cycle and therefore application of the H* leak rate factor discussed in the Vogtle 1 R18 Steam Generator Degradation Assessment is not applicable. Based on the inspection data in comparison with the limits, condition monitoring has been met at the 1 R 18 inspection for the degradation associated with PWSCC at tube bulge and overexpansion locations.

Table 7 Vogtle 1 R18 PWSCC at BLG/OXP indications or Anomalies

SG Row Column Indication Location Crack Angle Max Depth Stabilized? (degree~ lo/~

4 11 75 SCI 1 TSH-3.04 20 94 Yes inches2

1SCI- Single Circumferential Indication ~SH - Tubesheet region on the Hot Leg side

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Enclosure


Number of tubes Plugged

Table 8 presents a summary list of all SG tubes plugged in 1 R18 and the related degradations.

Table 8 Vogtle 1 R18 Plugging list

SG Row Column Indication 4 49 54 PCT1

4 11 75 SCI~

4 9 106 SCI 4 6 108 MCI6

4 8 109 SCI 4 6 111 SCI 4 9 111 MCI 4 7 112 SCI 4 6 113 SCI 4 4 116 SCI

1PCT- Volumetric Wear Indication 2AVB- Anti-vibration Bar 3SCI -Single Circumferential Indication

Degradation Mechanism AVB2 wear PWSCC4 at tubesheet bulqe ODSCC0 at HL overexpansion transition ODSCC at HL overexpansion transition ODSCC at HL overexpansion transition ODSCC at HL overexpansion transition ODSCC at HL overexpansion transition ODSCC at HL overexpansion transition ODSCC at HL overexpansion transition ODSCC at HL overexpansion transition

4PWSCC- Primary Water Stress Corrosion Cracking Indication 50DSCC- Outside Diameter Stress Corrosion Cracking Indication 6MCI - Multiple Circumferential Indication

Total plugging per Steam Generator is as follows:

SG 1 - 28 tubes for a total of 0.50% tubes plugged SG2 - 21 tubes for a total of 0.37% tubes plugged SG3 - 34 tubes for a total of 0.60% tubes plugged SG4 - 78 tubes for a total of 1.38% tubes plugged Total tubes plugged for all Unit 1 SGs: 161; 0.72%

Tube slippage Monitoring and Leakage Considerations

The bobbin data collected from SG1 and SG4 have been scrutinized for large amplitude tubesheet indications of greater than 50 volts with a phase angle between 25 and 50 degrees suggestive of tube severance. Both manual and automated data screenings have been performed with tube sever indications (SVR) as the code to report should a sever-type signal be detected. No SVR call was made for the entirety of the bobbin data collected.

For condition monitoring, primary to secondary side leakage attributable to the portion of tubing below the alternate repair criteria depth must be multiplied by a factor of 2.48 and added to the total leakage from any other source. This sum is then to be compared to the allowable accident induced leakage. There was no SG primary to secondary side leakage present during Cycle 18 and therefore the performance criteria relative to the permanent alternate repair criteria have been satisfied.

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Enclosure


Condition Monitoring Conclusions

Based on the inspection data and the condition monitoring 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 inspection interval. No secondary side tube degradation attributable to known foreign objects has been identified and all PLPs identified have been confirmed as historical and unchanged.

No anomalous conditions, such as a degraded tube plug or surrounding boron deposits, were reported during the visual inspections of the tube plugs in all four SGs. No operating leakage was reported during the previous cycle; therefore, the calculated accident induced leakage rate is zero.

Evaluation of the indications found in the 1 R18 inspections confirms that the SG tube integrity performance criteria for structural integrity, accident induced leakage, and operational leakage performance criteria condition monitoring requirements specified in Regulatory Guide 1.121 and NEI 97-06, revision 3, are satisfied and will be maintained.

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