NL-10-1499, Response to Request for Additional Information Related to Fifteenth, Maintenance/Refueling Outage Steam Generator Tube Inspection Report

Response to Request for Additional Information Related to Fifteenth, Maintenance/Refueling Outage Steam Generator Tube Inspection Report

ML102210415
Person / Time
Site:	Vogtle
Issue date:	08/06/2010
From:	Ajluni M Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-10-1499
Download: ML102210415 (18)

Text

Southern Nuclear Operating Company, Inc.

40 Inverness Center Parkway Post Office Bax 1295 Birmingham, Alabama 35201-1295 Tel 205.992.5000 August 6, 2010 SOUTHERN COMPANY Docket Nos.: 50-424 NL-10-1499 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant-Unit 1 Response to Request for Additional Information Related to Fifteenth Maintenance/Refueling Outa-ge Steam Generator Tube Inspection Report Ladies and Gentlemen:

By letter dated April 13, 2010 (Agencywide Documents Access and Management System (ADAMS), Accession Number ML101040084), Southern Nuclear Operating Company, Inc. (SNC), submitted information summarizing the results of the 2009 steam generator (SG) tube inspections at Vogtle Unit 1. In addition, by letter dated February 1, 2010 (ML100560265), SNC submitted the results of the destructive examination of two tubes removed from Vogtle Unit 1 during the 2008 outage. On June 16, 2010, the NRC provided SNC with Request for Additional Information (RAI) letter (ML101620128) containing 9 questions regarding the 1 R15 Steam Generator Inspection Report and the destructive examination results for tubes pulled during 1 R14. The June 16, 2010 letter requested responses to these 9 questions within 60 days.

Enclosure 1 contains the SNC responses to the 9 NRC questions contained in the June 16, 2010 letter.

Enclosure 2 contains the revised Vogtle 1 R1 5 Steam Generator Inspection Report.

This letter contains no NRC commitments. If you have any questions, please contact Jack Stringfellow at (205)992-7037.

Respectfully submitted, M. J. Ajluni Nuclear Licensing Director MJA/TAH/lac 0 1o

U. S. Nuclear Regulatory Commission Log: NL 10-1499 Page 2

Enclosures:

1. SNC Responses to Request for Additional Information

2. Revised Vogtle 1R15 Steam Generator Inspection Report cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. T. E. Tynan, Vice President - Vogtle Ms. P. M. Marino, Vice President - Engineering RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Vogtle Mr. M. Cain, Senior Resident Inspector - Vogtle Mr. P.G. Boyle, NRR Project Manager

Vogtle Electric Generating Plant - Unit I Response to Request for Additional Information Related to Fifteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report Enclosure I Response to Request for Additional Information

Enclosure 1 Response to Request for Additional Information By letter dated April 13, 2010 (Agencywide Documents Access and Management System (ADAMS), Accession Number ML101040084), Southern Nuclear Operating Company, Inc.

(SNC), submitted information summarizing the results of the 2009 steam generator (SG) tube inspections at Vogtle Unit 1. In addition, by letter dated February 1, 2010 (ML100560265), SNC submitted the results of the destructive examination of two tubes removed from Vogtle Unit 1 during the 2008 outage. On June 16, 2010, the NRC provided SNC with Request for Additional Information (RAI) letter (ML101620128) containing 9 questions regarding the 1 R15 Steam Generator Inspection Report and the destructive examination results for tubes pulled during 1 R14. The June 16, 2010 letter requested responses to these 9 questions within 60 days.

Responses to RAI questions 1 through 9 are provided below.

NRC Question 1 Please discuss the scope and results of your secondaryside inspections.

SNC Response Secondary Side Inspection and Maintenance activities performed were Sludge Lance, Foreign Object Search and Retrieval (FOSAR), Upper Bundle/In-Bundle (UBIB), 7 th Tube Support Plate (TSP), and Upper Internals.

Sludge lancing removed a total of twenty-five pounds of material from all four generators.

After FOSAR, 16 metallic objects remained in the generators. These objects were all categorized as Category 3. Category 3 indicates that the foreign object will not cause significant tube wear. This classification is taken from EPRI Report Number 1019039, "Steam Generator Management Program: Foreign Object Prioritization Strategy for Square Pitch Steam Generators" May 2009.

The UBIB and 7 th TSP inspection in SG1 did not find any anomalous conditions.

In SG4, a 7 th TSP inspection was performed to inspect the damage from the 1 R14 tube pull.

Images from 1 R15 were compared to images from 1R14 and it was determined that no visual changes had taken place.

The Upper Internals Inspection in all four generators found mild erosion/corrosion on the swirl vanes and mild FAC on the Feed Ring. All locations were evaluated as acceptable.

NRC Question 2 SNC indicatedthat upon approvalof H* for cycle 16 that "35% at HL ITS [hot leg top of tube sheet] +/ 14" [inches] capturedthe requiredBLGIOXP [bulge and overexpansion]

locations down to the H* depth of 13.1 "." Pleaseclarify this statement. Forexample, is this statement implying that by inspecting 35% of the tubes from 3 inches above to 14 inches below the top of the tube sheet that 100% of the bulges and over expansions were inspected?

Page 1 of 4

Enclosure 1 Response to Request for Additional Information SNC Response The percentage of bulges and over expansions required for inspection were encompassed by inspecting 35% of the tubes in each SG from 3 inches above to 14 inches below the top of the tube sheet. The required inspection of bulges and over expansions was 50% in SGs 1, 2, and 3 and 100% in SG 4. 100% of the bulges and over expansions were not inspected in SGs 1, 2, and 3.

NRC Question 3 On page 3 of 10 in the April 13, 2010 letter, there is a table of the outside diameterstress corrosioncracking indicationsdetected during the 2009 outage. Please verify the voltages for the indicationslocated in the tube in row 7, column 106 of SG 1 since 13.00 volts is large and appears to contradicta statement on page 10 that indicates the maximum voltage was only 0.31 volts.

SNC Response The correct voltage for the indication in R7C106 of SG1 was 0.13V. The 1 R15 Steam Generator Tube Inspection Report (enclosure to the April 13, 2010 letter) has been revised and is contained in Enclosure 2.

NRC Question 4 On page 4 of 10 in the April 13, 2010 letter, there is a table summarizing indicationsof wear attributedto loose-parts. In referencingthe table, SNC states that the indications referenced in the table were "re-confirmed"during the 2009 outage. Please confirm that all of these indications were present in prior outages since the staff was not able to locate the prior history for the indicationsin row 1, column 70; row 1, column 78; row 1, column 82; row 1, column 91; and row 40, column 106 from its review of some of the more recent reports summarizing the inspection findings at Vogtle. In addition,the indicationin row 41, column 100 in SG 1, appears to have grown since the last inspection (i.e., more than the staff would typically expect based on normal eddy current sizing variability). Pleasediscuss whether a visual inspection was performed to confirm the absence of a loose part at this location and all other locations (even if no possible loose part signal was present since the part may be non-conducting). Please discuss whether the loose part was removed from this location. Please confirm that an analysis was performed confirming that tube integrity would be maintained until the next scheduled inspection.

SNC Response The following indications should not have been titled loose parts wear indications: SG2 R1 C70, Ri C78, R1 C82, R1 C91, and SG4 R40C1 06. They are volumetric indications, but were not caused by loose parts wear. The indications in SG2 Ri C70, Ri C78, and R1iC82 were reported in the 1 R1 3 Steam Generator Tube Inspection Report as shallow wall loss caused by cavitations during ultrasonic energy cleaning (UEC). These indications are unchanged from that report. The title of this table has been changed to Vogtle 1 Volumetric Indications for 1 R1 5 in the revised 1 R15 Steam Generator Tube Inspection Report (enclosure to the April 13, 2010 letter) and is Contained in Enclosure 2 Page 2 of 4

Enclosure 1 Response to Request for Additional Information The R1iC91 indication is attributed to pressure pulse cleaning (PPC) that was last performed during 1 R5. This indication has not exhibited a change in the last 3 inspections performed; therefore, no progression of this degradation mechanism has occurred.

A history review has been performed on the two volumetric indications in SG1 R41C100. The changes in percent through wall (TWD) are shown in the table below.

SG I Row I Col I 1R15 I 1R14 I 1R13 I 1R12 L1 141 100 31 29 30 28 1i 41 100 116 115 114 114 The differences in the results for the last 4 inspections are regarded as within the bounds of technique uncertainty and do not represent progression of the VOL indications. These indications were visually inspected in 1 R1 3 and 1 R1 4 and no loose part was present.

The indication in SG4 R40C106 was reported in 1R14 as AVB wear and has not grown. This tube was inspected in 1 R1 5 as part of the bobbin inspection surrounding the 1 R1 4 tube pull damage. The 100% bobbin inspection was performed in SG 2 and SG 3.

NRC Question 5 On page 10 of 10 in the April 13, 2010 letter, SNC indicates that no new axial outside diameterstress corrosioncracking indicationshave been found since 1R13. Please verify. Wasn't an axial indication found during 1R14 in 2008 (i.e., in row 11, column 62 in steam generator4)?

SNC Response The enclosure should have stated that no new indications have been found since 1 R1 4. There was a new Single Axial Indication (SAI) called in SG4 R11C62 in 2008. The 1 R15 Steam Generator Tube Inspection Report (enclosure to the April 13, 2010 letter) has been revised and is contained in Enclosure 2.

NRC Question 6 On page 1 of 10 in the third bullet, SNC states that several tubes have been identified with non-optimal (Seabrook-type) tube processing(through review of eddy current data).

Please discuss the extent to which cracking (atany location)has been observed in these tubes.

SNC Response One crack like indication (SG2 R1 6C116 in 2008 MAI at TEH) has been seen in the 2a tubes.

This was found at TEH +0.24".

NRC Question 7 On page 1-1 of the Westinghouse report submitted with your February 1, 2010 letter, it was indicated that the flow distributionbaffle has octofoil shaped holes; however, on page 2-3, SNC indicates that the holes are drilled (presumablyround). Please clarify the shape of the holes in the flow distributionbaffle.

Page 3 of 4

Enclosure 1 Response to Request for Additional Information SNC Response The shape of the holes in the flow distribution baffle plate is round. They are drilled.

NRC Question 8 On page 1-1 and 1-2 of the Westinghouse report submitted with your February1, 2010 letter, it was stated that all of the outside diameter stress corrosioncracking indications reportedduring your 2009 outage were present in the 2008 inspection data but were allowed to remain in service as TRA (presumablytrackable anomaly) signals. Please discuss if tubes with such flaw signals were left in service during the 2009 inspections and if so, the basis for the decision.

SNC Response After the tube pull analysis was performed, all trackable anomaly (TRA) indications that were confirmed with +Point were plugged. All TRA indications with this signal history in the future will be plugged as well.

NRC Question 9 Please explain the markings in the 225-degree portion of Figure2-7 in the Westinghouse reportsubmitted with your February 1, 2010, letter since it is not clearto the staff, where the wear indicationis located.

SNC Response As documented in Section 2.6 of the referenced letter, the markings at the 225-degree location are not wear marks. The markings in Figure 2-7 (2250) consist of six gripper marks, which are vertically orientated in the picture and a fresh scratch, which runs horizontal in the picture.

These indications are discussed in Section 2.2.2 paragraph 4 and are found at other orientations around the circumference at the elevation where the TSP1 is located. There was no service, manufacturing, maintenance or loose part induced wear present on the pulled tubes.

The gripper marks and scratches shown in Figure 2-7 are an artifact of the tube pulling operation and are not a service-induced feature. The faint band of deposits shown in Figure 2-7 (2250), that run horizontal in the picture on the lower half of the picture are the remnants of the deposits that formed in the gap between the tube and one of the quatrefoil lands of the support plate, as is indicated by the label "Land Contact". This is also discussed in Section 2.6.

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Vogtle Electric Generating Plant - Unit 1 Response to Request for Additional Information Related to Fifteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report Enclosure 2 Revised 1 R15 Steam Generator Tube Inspection Report

Enclosure 2 Revised Vogtle 1 R15 Steam Generator Inspection Report 1 R1 5 STEAM GENERATOR TUBE INSPECTION REPORT Introduction The 1 R1 5 outage was conducted after cumulative service equivalent to - 19.8 EFPY (effective full power years); the Cycle 15 power generation was -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 Reg. Guide 1.121 and NEI-97-06 Revision 2 criteria for tube integrity during Cycle 15. During shutdown, primary-to-secondary leakage below the Vogtle Technical Specification limit was detected and evaluated. One tube, (SG3 R1C20) was subjected to in situ pressure testing based on an apparent axial primary water stress corrosion cracking (PWSCC) indication near the tangent point of the U-bend, but no leakage was seen at Normal Operating differential pressure. A small amount of leakage was observed at Main Steam Line Break differential pressure and above, but all Condition Monitoring criteria were satisfied. The eddy current inspections and in situ testing 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.

1 R15 Scope The scope for 1 R1 5 involved the scheduled inspections listed below. The inspection program addressed the known degradation mechanisms observed in Vogtle Unit 1 in prior inspections, as well as those regarded as potential degradation mechanisms.

• 100% Bobbin examination of tubes in SGs 2 and 3, full length except for Rows 1 and 2, which are inspected from tube end to TSP#7 from both HL and CL.

• +Point (mid-range) examination of 50% small radius U-bends (Row 1 and Row 2) in all SGs

• +Point (mid-range) examination of Special Interest, HL and CL, of bobbin possible flaw locations including U-bends. Tubes indicating Seabrook-type U-bend offset behavior, with DSIs (TSP indications) that are not confirmed, will nonetheless be preventively plugged.

0 +Point (mid-range) examination 100% at HL TTS, +/- 3" in all SGs and 25% CL in SG2 and SG3. Upon approval of the one-cycle of H* criteria for Cycle 16, 35% at HL TTS +/-

3"/-14" captured the required BLG/OXP locations down to the H* depth of 13.1". The remaining 65% of the HL population was inspected TTS + 3, while the CL TTS inspections were unaffected.

- 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.

• Bobbin full length examination of the region in SG4 adjacent to tubes affected by the tube pull event. The scope of this testing was bobbin probe examination of a two tube box around the stabilized tubes surrounding the tube pull location at Ri 1C62 and for columns 61, 62, and 63 rows 14 through 25.

0 +Point examination of 100% of dents and dings >2 volts in HL straight length free span of SG2 and SG3.

Page 1 of 10

Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report 0 +Point examination of 100% of dents and dings -2 volts in U-Bends of SG1 and SG4.

• Visual inspection of tube plugs in all 4 SGs.

As a result of the axial indication found during the base scope inspection at R1 C20 in SG3, the scope was expanded from 50% to 100% of U-Bend RPC in all SGs, and to 20% of Row 3 U-Bends in SG3. All previous data was reviewed for a similar indication.

Damage Mechanisms Found and NDE Techniques Utilized The following damage mechanisms were discovered in the Vogtle Unit 1 SGs during 1 R1 5:

" Outside diameter stress corrosion cracking (ODSCC) at the top of the tube sheet was found in 20 tubes among the 4 SGs. The +Point probe was used to inspect 100% of the top of the tube sheet in all four SGs.

" A single axial PWSCC indication was found above the HL tangent point in SG3 (R1 C20).

The +Point probe was used for the small radius U-bend inspection.

" Antivibration bar (AVB) wear was found in SG 2 and SG3. AVB wear is identified during the bobbin inspection.

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Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report Service Induced Indication Descriptions ODSCC Outside diameter stress corrosion cracking identified in Vogtle 1R1 5 is provided in the following table:

Vog 1ODSCC Indications for 1 R15 SG Row Col Volts Ind' Max. Depth Circumferential Degraded Area

(%) Extent (deg) (%)

1 2 113 0.07 MCI' 93.0 67.0 11.40 1 3 108 0.13 MCI 85.0 73.0 8.10 1 5 110 0.10 SC12 68.0 73.0 2.20 1 7 106 0.13 SCI 97.0 73.0 3.20 1 7 106 0.13 SCI 74.0 73.0 3.00 1 7 117 0.11 SCI 42.0 67.0 2.10 1 8 115 0.09 SCI 44.0 67.0 2.00 1 8 115 0.09 SCI 32.0 67.0 1.10 1 10 104 0.16 SCI 72.0 67.0 3.20 1 10 112 0.07 MCI 90.0 73.0 19.30 1 12 120 0.14 SCI 53.0 69.0 3.10 1 15 115 0.09 SCI 40.0 67.0 2.10 2 13 62 0.31 SCI 98.0 13.0 3.90 2 22 103 0.10 SCI 73.0 73.0 3.30 3 2 109 0.11 MCI 52.0 79.0 5.40 3 3 106 0.11 SCI 76.0 81.0 2.60 3 6 114 0.25 SCI 81.0 79.0 4.30 3 7 113 0.12 SCI 88.0 81.0 2.60 4 3 105 0.10 SCI 80.0 73.0 5.40 4 4 113 0.06 SCI 10.0 77.0 <1.00 4 4 117 0.09 SCI 34.0 77.0 2.10 4 4 122 0.13 SCI 84.0 79.0 3.80 The inspection result was classified as an indication type in accordance with a convention of 3-letter codes used for grouping and tracking various types of indications.

2 SCI - Single circumferential indication 3

MCI - Multiple circumferential indication The circumferential ODSCC flaws were located at the bottom of the hydraulic expansion transition at the top of the tube sheet.

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Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report PWSCC Primary water stress corrosion cracking identified in Vogtle 1 R15 is provided in the following table:

Vogtle 1 Axial PWSCC in Small Radius U-Bend for 1R15 SG Row Col Volts Ind Max. Depth Axial Length

(%) (inches) 3 1 20 3.09 SAl 100.0 0.54 1 SAI - Single axial indication Volumetric Indications Volumetric indications re-confirmed in Vogtle 1 R1 5, are provided in the following table:

Votie 1 Volumetric Indications for 1R15 SG Row Col Volts %TWD Locn 1 39 100 0.70 13.0 TSiH 1 41 100 2.05 31.0 TSH 1 41 100 0.85 16.0 TSH 1 41 101 1.46 24.0 TSH 1 41 102 1.27 22.0 TSH 1 41 103 1.36 23.0 TSH 2 1 70 0.28 6.0 TSC 2 1 70 0.40 8.0 TSC 2 1 70 0.18 4.0 TSC 2 1 78 0.04 4.0 TSC 2 1 78 0.09 8.0 TSC 2 1 82 0.05 5.0 TSC 2 1 91 0.17 15.0 BP-C 2 6 1 0.07 7.0 1C 2 16 6 0.10 12.0 BPC 2 16 7 0.33 29.0 BPC 3 30 111 1.96 29.0 B6PH 4 40 106 0.27 16.0 A 12 TSH TSC -- Tubesheet Tubesheet region region on on HL CL side.

side 3 BPC - Flow distribution baffle plate on CL side 4 1C-Row 1 CL side 5 BPH - Flow distribution baffle plate (FDB) on HL side 6 AV - Antivibration Bar Page 4 of 10

Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report A VB Wear AVB wear continued to be identified in Vogtle 1 R15 in SG2 and SG3. AVB wear identified is provided in the tables below:

yoge1 R15: SG2 AVB Wear Indications Row Col Location' 1R15% Row Col Location 1R15 %

26 49 AV2 11.0 43 88 AV3 17.0 26 114 AV1 9.0 43 88 AV5 16.0 27 115 AV6 10.0 43 91 AV2 28.0 28 112 AV6 10.0 43 91 AV3 17.0 32 12 AV1 10.0 43 91 AV4 11.0 32 12 AV3 18.0 43 91 AV5 30.0 34 106 AV3 16.0 43 93 AV2 12.0 34 108 AV4 14.0 43 93 AV3 21.0 35 13 AV3 9.0 43 93 AV4 22.0 35 13 AV4 11.0 43 93 AV5 12.0 35 13 AV5 11.0 43 94 AV2 13.0 35 13 AV6 9.0 43 94 AV3 13.0 35 14 AV5 11.0 43 95 AV4 15.0 35 17 AV3 10.0 43 96 AV5 13.0 35 25 AV3 9.0 43 98 AV3 15.0 35 32 AV4 11.0 43 98 AV4 30.0 35 83 AV3 12.0 43 98 AV5 43.0 35 83 AV5 15.0 43 98 AV6 10.0 35 83 AV6 13.0 43 101 AV4 19.0 35 100 AV5 10.0 46 49 AV3 25.0 35 104 AV3 11.0 46 49 AV4 16.0 35 105 AV5 12.0 46 50 AV1 21.0 36 13 AV3 7.0 46 50 AV2 33.0 36 108 AV6 9.0 46 50 AV3 33.0 37 97 AV3 11.0 46 50 AV4 29.0 38 15 AV6 9.0 46 50 AV5 26.0 38 89 AV2 10.0 46 50 AV6 13.0 38 89 AV4 12.0 46 53 AV5 8.0 38 89 AV5 16.0 46 58 AV2 17.0 38 106 AV5 24.0 46 58 AV4 12.0 38 108 AV3 10.0 46 58 AV5 13.0 38 108 AV4 13.0 48 97 AV1 10.0 39 38 AV2 17.0 48 97 AV2 16.0 39 103 AV5 19.0 48 97 AV3 34.0 39 105 AV5 17.0 48 98 AV3 11.0 40 37 AV4 14.0 48 98 AV4 17.0 40 41 AV3 12.0 48 98 AV5 18.0 40 41 AV4 11.0 48 98 AV6 24.0 40 93 AV2 15.0 49 89 AV3 11.0 40 93 AV5 20.0 49 89 AV4 20.0 40 98 AV5 18.0 49 89 AV5 25.0 1 AV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report Vo tie 1R15: SG2 AVB Wear Indications (continued)

Row Col Location 1R15 % Row Col Location 1R15 %

41 33 AV4 25.0 50 83 AV2 11.0 41 33 AV5 22.0 50 84 AV2 12.0 41 42 AV2 17.0 50 84 AV3 29.0 41 42 AV3 13.0 50 84 AV4 21.0 41 42 AV4 32.0 50 84 AV5 11.0 41 42 AV5 37.0 50 89 AV2 16.0 41 102 AV3 20.0 50 89 AV3 15.0 41 102 AV5 35.0 50 89 AV4 28.0 42 76 AV1 9.0 50 92 AV2 15.0 42 76 AV2 31.0 50 92 AV3 17.0 42 76 AV3 19.0 51 81 AV2 12.0 42 76 AV4 21.0 51 81 AV4 13.0 42 76 AV5 38.0 52 91 AV2 17.0 42 76 AV6 21.0 52 91 AV5 12.0 42 86 AV3 12.0 53 61 AV5 11.0 42 92 AV4 17.0 53 79 AV2 17.0 42 92 AV5 13.0 53 79 AV3 22.0 42 94 AV3 18.0 53 83 AV2 31.0 42 94 AV4 25.0 53 83 AV3 28.0 42 94 AV5 15.0 54 84 AV2 10.0 42 96 AV3 13.0 54 84 AV3 21.0 42 96 AV4 18.0 54 84 AV4 21.0 42 96 AV5 17.0 54 84 AV5 24.0 42 97 AV2 12.0 54 85 AV2 21.0 42 97 AV3 16.0 54 85 AV3 37.0 42 97 AV4 25.0 54 85 AV4 32.0 42 100 AV3 18.0 54 85 AV5 46.0 42 100 AV4 21.0 54 85 AV6 13.0 43 68 AV3 14.0 55 59 AV3 14.0 43 68 AV5 14.0 55 59 AV3 12.0 43 87 AV2 14.0 55 59 AV5 11.0 43 87 AV3 16.0 55 83 AV5 16.0 43 87 AV4 9.0 55 84 AV5 19.0 43 87 AV5 19.0 57 72 AV1 12.0 43 88 AV2 10.0 57 79 AV5 16.0 1 AV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report

____le1 R15:SG3 AVB Wear Indications Row Col Location' 1R15 % Row Col Location 1R15 %

28 8 AV6 23 42 28 AV2 10 28 8 AV1 14 42 28 AV4 10 32 52 AV1 13 42 29 AV4 20 35 16 AV3 11 42 35 AV4 19 36 13 AV5 12 42 43 AV2 19 36 34 AV5 15 42 43 AV5 19 36 34 AV2 12 42 43 AV6 14 36 44 AV5 12 42 50 AV4 38 36 44 AV2 10 42 50 AV2 31 37 107 AVl 13 42 50 AV3 18 37 107 AV5 12 42 50 AVl 8 37 108 AV6 13 42 58 AV3 18 38 34 AV5 13 .42 58 AV2 10 38 35 AV5 12 1 42 63 AV4 16 38 69 AV3 9 42 66 AV4 18 38 106 AV3 17 42 66 AV3 13 38 106 AV6 17 42 67 AV3 12 38 106 AV5 12 44 22 AV5 15 38 107 AV4 14 44 102 AV4 12 39 17 AV3 25 45 22 AV5 12 39 17 AV6 25 45 40 AV3 16 39 17 AV4 21 45 40 AV4 15 39 17 AV2 11 45 40 AV5 15 39 20 AV4 11 45 40 AV6 9 39 26 AV2 20 45 46 AV3 28 39 35 AV3 29 45 46 AV2 27 39 35 AV4 24 45 46 AV4 20 39 35 AV5 15 45 46 AV5 13 39 48 AV4 11 45 46 AVl 10 39 51 AV3 9 45 48 AV3 26 39 62 AV4 9 45 48 AV2 17 39 63 AV3 16 45 48 AV5 15 39 66 AV3 17 45 49 AV3 24 39 66 AV5 17 45 49 AV2 20 39 66 AV4 14 45 61 AV5 22 39 67 AV3 12 45 61 AV4 19 39 67 AV4 10 45 62 AV3 35 39 102 AV2 16 45 62 AV4 35 39 102 AV5 13 45 63 AV3 33 39 104 AV5 25 45 63 AV4 20 39 104 AV4 10 45 64 AV3 14 40 19 AV5 16 45 67 AV4 18 40 19 AV4 14 45 67 AV3 17 40 19 AV6 13 45 69 AV5 12 40 30 AV5 22 45 69 AV2 10 IAV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure 2 Revised Vogtle 1 R1 5 Steam Generator Inspection Report Vogtl 1R15: SG3 AVB Wear Indications (continued)

Row Col Location 1R15 % Row Col Location 1R15 %

40 35 AV4 15 45 77 AV2 13 40 97 AV3 17 45 77 AV4 11 40 97 AV4 14 45 82 AV3 14 40 98 AV2 15 45 82 AV4 13 40 100 AV5 14 46 25 AV5 19 40 100 AV2 13 46 25 AV4 15 40 101 AV2 13 47 26 AV5 14 40 101 AV5 13 47 35 AV4 17 40 102 AV2 18 47 38 AV4 25 40 102 AV6 14 47 45 AV4 18 40 104 AV4 22 47 45 AV2 15 40 105 AV6 16 47 95 AV6 11 41 19 AV5 20 47 96 AV4 20 41 19 AV4 15 49 92 AV5 13 41 19 AV3 14 49 96 AV6 21 41 20 AV4 12 49 96 AV4 15 41 20 AV5 12 49 96 AV5 15 41 21 AV5 14 50 86 AV2 15 41 21 AV4 10 50 86 AV5 13 41 102 AV3 34 51 55 AV4 13 41 102 AV4 24 51 82 AV4 31 41 102 AV2 15 51 82 AV5 24 41 102 AV6 12 51 82 AV3 13 42 21 AV5 20 51 92 AV6 15 42 21 AV4 16 53 84 AV4 32 42 21 AV3 15 53 84 AV3 22 42 21 AV2 12 53 84 AV5 15 42 23 AV4 13 54 88 AV1 13 42 26 AV5 13 54 88 AV6 12 42 26 AV4 11 58 52 AV6 13 42 27 AV5 31 59 61 AV4 13 42 27 AV4 15 59 68 AV6 14 1 AV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report Number of Tubes Plumged Table 1 presents a summary list of all SG tubes plugged in Vogtle 1 R1 5 and the related degradation mechanism.

Table 1: 1 R15 Plugged Tubes (25)

SG Row Col Ind Degradation Mechanism 1 2 113 MCI ODSCC 1 3 108 MCI ODSCC 1 5 110 SCI ODSCC 1 7 106 SCI ODSCC 1 7 117 SCI ODSCC 1 8 115 SCI ODSCC 1 10 104 SCI ODSCC 1 10 112 MCI ODSCC 1 12 120 SCI ODSCC 1 15 115 SCI ODSCC 1 7 35 PVN Administrative 1 44 60 RRT Administrative 2 13 62 SCI ODSCC 2 22 103 SCI ODSCC 2 43 98 PCT AVB Wear.

2 54 85 PCT AVB Wear 3 1 20 SAI PWSCC 3 2 109 MCI ODSCC 3 3 106 SCI ODSCC 3 6 114 SCI ODSCC 3 7 113 SCI ODSCC 4 3 105 SCI ODSCC 4 4 113 SCI ODSCC 4 4 117 SCI ODSCC 4 4 122 SCI ODSCC Total plugging in the SGs after 1 R1 5 is as follows:

SG1 - 27 tubes for a total of 0.43% tubes plugged SG2 - 19 tubes for a total of 0.34% tubes plugged SG3 - 33 tubes for a total of 0.59% tubes plugged SG4 - 67 tubes for a total of 1.19% tubes plugged Page 9 of 10

Enclosure 2 Revised Vogtle 1R15 Steam Generator Inspection Report In Situ Testing Non-destructive evaluation (NDE) data determined the axial indication in SG3 RI C20 exceeded 80% depth over 0.28 inches in one segment and over 0.16 in a second segment. Its maximum

+Point amplitude was 3.09 volts in the longer of the 2 segments, which exceeds the threshold voltage for leakage in the EPRI Steam generator In Situ Pressure Test Guidelines, Revision 3.

The total length of the indication exceeded the proof of pressure testing criteria of 0.4 inches set forth in the 1 R1 5 Degradation Assessment.

No detectable leakage was observed at APNO (AP = 1323 psi) adjusted for temperature and gage uncertainty (actual test pressure 1700 psig). At MSLB conditions (AP= 2650 psi), adjusted to exceed 3046 psi to an actual test pressure 3200 psig, the observed leakage was 77.2 ml over 10 minutes, equivalent to 0.002 gpm. The results of the in situ test indicate that a short length of the crack is through-wall; the flaw is interrupted by part through-wall ligaments which increase the apparent strength of the tube. Since the leakage at MSLB pressure did not exceed 1gpm (0.25 gpm per worst case SG), and the tube did not burst at 3APNO, the condition monitoring requirements have been satisfied.

Condition Monitoring Conclusions No indications were found to exceed the condition monitoring limits specified in the Degradation Assessment.

No indications of axial ODSCC were reported. No new axial ODSCC indications have been found since 1 R1 4. The absence of reportable axial ODSCC for cycle 15 presents no condition monitoring concern.

Tube pull analyses confirmed circumferential ODSCC at the top of tubesheet. Twenty tubes were identified as circumferential ODSCC across all SGs. None of these tubes passed the screening for in situ testing. The largest amplitude (SG2 R1 3C62) was determined to have 0.31 volts. The largest circumferential extent (SG1 R1OCI 12) maintained a crack depth of 19.3%; far below the condition monitoring limit of 55.0%.

Primary-to-secondary leakage was not detected during the cycle. During cool down, a small amount of leakage was detected, but was not measurable. SG3 R1iC20 axial PWSCC was suspected to be responsible for the leakage and was subjected to in situ testing after exceeding length limits and +Point amplitudes. The results of the in situ testing revealed no leakage at APNO and very low leak rates at both MSLB and 3APNO conditions adjusted, which satisfied the condition monitoring criteria.

None of the AVB wear indications in either SG2 or SG3, adjusted for the sizing model and the 95% probability measurement error associated with the measurement technique, exceed the Condition Monitoring limits as given in the 1 R1 5 Degradation Assessment.

Given the absence of operating leakage during Cycle 15, it is concluded that there was no leakage from plugs. This is consistent with the video inspection of the tube plugs in all 4 SGs which produced no exceptions to expected conditions.

Evaluation of the indications found in the 1R1 5 inspections confirms that the tube integrity structural and leakage performance criteria condition monitoring requirements as specified in NEI-97-06 Revision 2 are satisfied Page 10 of 10