NL-08-1592, Fourteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report

Fourteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report

ML082911083
Person / Time
Site:	Vogtle
Issue date:	10/17/2008
From:	Ajluni M Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-08-1592
Download: ML082911083 (13)

Text

Southern Nuclear Operating Company. Inc.

Post Office Box 1295 Birmingham. Alabama 35201-1295 Tel 205,992,5000 SOUTHERN'\

COMPANY Energy to Serve Your World'*

October 17, 2008 Docket No.: 50-424 NL-08-1592 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant - Unit 1 Fourteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report Ladies and Gentlemen:

In accordance with the requirements of Vogtle Electric Generating Plant Technical Specification 5.6.10, Southern Nuclear Operating Company submits this report of the steam generator tube inspections performed during the Unit 1 fourteenth maintenancelrefueling outage (1R14). Entry into Mode 4 occurred on April 20, 2008.

This letter contains no NRC commitments. If you have any questions, please advise.

Sincerely, fYLwl%or M. J. Ajluni Manager, Nuclear Licensing MJAlDRG/daj

Enclosure:

1R14 Steam Generator Tube Inspection Report cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. T. E. Tynan, Vice President - Vogtle Mr. D. H. Jones, 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. G. J. McCoy, Senior Resident Inspector - Vogtle

Vogtle Electric Generating Plant - Unit 1 Fourteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report Enclosure 1R14 Steam Generator Tube Inspection Report

Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report Introduction The 1R14 outage was conducted after cumulative service equivalent to ~ 18.4 EFPY (effective full power years); the Cycle 14 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. 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 to Southern Nuclear.

1R14 Base Scope The base scope for 1R14 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 1 and 4, full length except for Rows 1 and 2, which are inspected from tube end to tube support plate (TSP) #7 from both hot leg (HL) and cold leg (CL).

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

2) in SGs 1 and 4, including all Row 1 and Row 2 tubes that were not +Point inspected in the U-bend during 1R12.

• 100% +Point examination (mid-range) HL top of tube sheet (TTS), +/- 3, in all SGs.

• 25% +Point examination of the tubes in each SG from the top of tube sheet hot (TSH) -17 to TEH (the hot leg end of the tube including the tube-end weld) -

based on approval of the interim alternate repair criteria (IARC) by the NRC.

y +Point tests of Special Interest bobbin locations (including U-bends).

• 25% of SG1, SG2, and SG3 populations and 100% of SG4 population +Point inspection of expanded tubesheet section BLGs and OXPs; TSH-17 to TSH+3; response to Catawba 2 finding. The sampled extents in SG1, SG2, and SG3 for this inspection program in the 1R14 outage do not include extents which were previously examined during the last 1R12 and 1R13 outages or during the applicable sequential inspection period, with exceptions only based on specific needs of the inspection.

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 examination of dents/dings 5 volts in U-bends in SG1 and SG4.

• Visual inspection of tube plugs in all 4 SGs.

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report As a result of indications found during the base scope inspection at TEH in SG2 and SG3, the scope was expanded from 25% to 100% of TEH in SG2 and SG3.

This expansion was performed before the Interim Alternate Repair Criteria was put in place for 1R14. In addition, the expansion increased the +Point inspection of expanded tubesheet section BLGs and OXPs to 100% in SG2 and SG3.

Damage Mechanisms Found and NDE Techniques Utilized The following damage mechanisms were discovered in the Vogtle Unit 1 SGs during 1R14:

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

Primary Water Stress Corrosion Cracking (PWSCC) at the tube ends was found in SG2 and SG3. The +Point probe was used to inspect 25% of the tube ends in SG1 and SG4 and 100% of the tube ends in SG2 and SG3.

Loose parts wear was found SG1 and SG4. +Point probe sizing was used to size the wear scars. Areas with potential loose parts and/or wear are identified during the bobbin inspections.

Antivibration bar (AVB) wear was found in SG1 and SG4. AVB wear is identified during the bobbin inspection except for rows 1 and 2 which are inspected with the +Point probe.

Service Induced Indication Descriptions Outside diameter stress corrosion cracking identified in Vogtle 1R14 is provided in the following table.

Vogtle 1 ODSCC Indications for 1R14 Maximum Percent

% Depth Circumferential SG Row Col Volts Ind1 Degraded (Phase Extent Area Sizing) 3 1 6 110 0.21 MCI 94% 215° 40.4 2

1 8 112 0.14 SCI 57% 37° 5.5 2

1 10 114 0.16 SCI 70% 76° 11.8 2

1 11 118 0.21 SCI 82% 51° 9.2 2

1 13 96 0.35 SCI 34% 50° 6.3 2

2 34 104 0.16 SCI 57% 74° 6.1 2

3 6 119 0.16 SCI 66% 60° 9.4 2

3 13 107 0.24 SCI 50% 62° 8.2 2

4 12 98 0.44 SCI 54% 51° 7.3 2

4 22 51 0.38 SCI 65% 64° 11.8 4

4 11 62 0.61 SAI 95% N/A N/A 1

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 4

SAI - Single axial indication E-2

Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report The circumferential ODSCC flaws were located at the bottom of the hydraulic expansion transition at the top of the tube sheet. The axial ODSCC flaw began at the bottom of the hydraulic expansion transition and extended into the expanded section of the tube inside the tube sheet. All tubes with ODSCC flaws were removed from service.

Loose parts wear indications, either identified or re-confirmed in Vogtle 1R14, are provided in the following table. The only new indication was SG4 R38C104. No PLP indications were found in this location; therefore, visual inspection was not required. The two Row 1 tubes with shallow wear ~ 18 above the tubesheet were traced to damage caused by interaction with the sludge monorail system used several outages ago. As expected there was no change in these residual signals since the wall loss indicated did not result from in-service degradation. All of the other indications have been visually inspected during earlier outages to confirm there were no loose parts at the locations.

Vogtle 1 Loose Parts Wear Indications for 1R14 1R14 SGID Row Col Volts TWD Locn 1

1 1 83 0.67 16 TSH 1

1 1 87 2.47 31 TSH 1

1 39 100 0.19 14 TSH 1

1 41 100 0.25 13 TSH 1

1 41 100 0.75 15 TSH 1

1 41 101 0.79 29 TSH 1

1 41 102 0.43 23 TSH 1

1 41 103 0.22 20 TSH 2

4 38 104 0.33 8 BPH 1

TSH - Tubesheet region on HL side.

2 BPH - Flow distribution baffle plate (FDB) on HL side AVB wear continued to be identified in Vogtle 1R14 in SGs 1 and 4. AVB wear identified is provided in the tables below.

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report Vogtle 1R14: SG1 AVB Wear Indications Col Row Location1 1R14 Col Row Location1 1R14 16 38 AV2 16 48 39 AV2 13 16 38 AV3 15 48 39 AV3 21 16 38 AV4 31 48 39 AV4 22 16 38 AV5 12 48 39 AV5 15 18 35 AV6 14 51 41 AV4 14 18 41 AV4 11 53 54 AV2 7 18 41 AV5 13 62 40 AV5 11 18 41 AV6 14 62 59 AV6 12 20 40 AV4 11 75 40 AV3 9 21 43 AV2 10 75 58 AV1 14 21 43 AV4 19 76 58 AV6 12 21 43 AV5 25 77 37 AV3 10 21 43 AV6 11 78 57 AV6 13 21 44 AV5 14 80 41 AV3 9 23 41 AV4 10 80 44 AV3 9 27 49 AV3 10 80 44 AV4 11 29 50 AV1 11 80 44 AV5 8 29 50 AV2 11 81 43 AV4 15 30 45 AV3 14 81 43 AV5 10 33 52 AV2 18 82 43 AV3 16 33 52 AV3 18 83 43 AV1 12 34 35 AV3 12 83 43 AV3 14 34 35 AV4 12 83 43 AV4 23 34 40 AV2 8 83 43 AV5 16 34 40 AV3 11 83 54 AV1 13 34 40 AV4 16 83 54 AV6 12 34 40 AV6 8 85 43 AV2 10 34 41 AV4 12 87 39 AV4 9 34 42 AV4 15 87 53 AV3 11 36 54 AV2 10 88 49 AV4 11 37 42 AV6 14 90 39 AV2 11 37 54 AV1 12 90 39 AV3 13 37 54 AV6 14 90 45 AV2 14 39 52 AV2 21 90 45 AV3 12 39 52 AV3 27 90 53 AV6 16 39 52 AV4 26 91 43 AV2 30 39 52 AV5 13 91 43 AV3 18 39 53 AV6 15 91 43 AV4 13 41 46 AV1 13 91 52 AV1 15 1

AV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report Vogtle 1R14: SG1 AVB Wear Indications (continued)

Col Row Location1 1R14 Col Row Location1 1R14 43 42 AV2 12 97 48 AV1 14 43 42 AV3 13 99 47 AV2 13 43 42 AV4 14 100 27 AV5 8 43 42 AV5 13 102 37 AV5 16 43 53 AV2 12 104 35 AV3 11 43 53 AV5 10 104 39 AV4 11 44 41 AV2 16 104 40 AV3 14 44 41 AV3 31 104 40 AV4 13 44 52 AV4 21 105 36 AV3 11 44 57 AV4 40 108 38 AV6 12 44 57 AV5 35 115 27 AV1 10 44 57 AV6 11 115 27 AV6 11 45 54 AV2 11 115 28 AV1 15 45 57 AV2 20 115 28 AV6 27 45 57 AV3 33 116 23 AV6 11 45 57 AV5 13 116 24 AV6 11 45 57 AV6 16 116 26 AV1 12 47 40 AV3 26 116 26 AV6 19 47 40 AV4 29 47 40 AV5 10 47 40 AV6 12 1

AV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report Vogtle 1R14: SG4 AVB Wear Indications Col Row Location1 1R14 Col Row Location1 1R14 8 27 AV6 14 90 53 AV1 12 9 27 AV5 17 90 53 AV5 13 9 30 AV2 17 90 53 AV6 12 9 30 AV5 34 91 33 AV2 8 12 33 AV2 9 92 40 AV3 10 12 33 AV3 9 92 40 AV5 14 12 33 AV6 8 92 43 AV3 13 13 36 AV2 11 93 40 AV2 10 14 36 AV1 10 93 40 AV5 10 20 30 AV2 8 95 40 AV2 13 22 45 AV5 11 95 40 AV3 12 23 41 AV2 11 95 40 AV4 27 24 40 AV5 14 95 40 AV5 11 25 40 AV3 11 95 49 AV3 12 29 40 AV2 12 96 38 AV2 10 34 33 AV3 14 96 38 AV4 8 34 33 AV4 12 96 38 AV5 11 34 33 AV5 14 96 44 AV2 9 36 54 AV5 14 96 44 AV3 24 38 54 AV1 10 96 44 AV4 24 39 36 AV3 19 96 44 AV6 12 39 40 AV3 11 97 41 AV5 12 40 28 AV5 17 97 44 AV2 14 40 30 AV5 14 97 44 AV4 19 40 55 AV6 11 97 44 AV5 22 41 56 AV5 11 97 48 AV6 10 43 27 AV5 8 99 44 AV6 9 46 43 AV6 18 100 40 AV2 11 48 58 AV5 10 100 40 AV3 8 51 27 AV2 11 100 40 AV4 11 51 39 AV3 9 100 40 AV5 10 51 39 AV4 12 100 40 AV6 11 51 39 AV5 12 100 42 AV2 15 51 39 AV6 15 100 42 AV3 11 52 38 AV3 8 100 42 AV4 16 52 38 AV4 11 101 42 AV3 12 54 49 AV2 18 101 42 AV4 18 54 49 AV3 26 101 42 AV5 17 54 49 AV4 30 101 43 AV4 13 1

AV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report Vogtle 1R14: SG4 AVB Wear Indications (continued)

Col Row Location1 1R14 Col Row Location1 1R14 54 49 AV5 22 101 43 AV5 21 55 38 AV4 9 101 45 AV1 11 55 57 AV6 12 101 45 AV5 8 56 39 AV3 15 101 45 AV5 8 56 39 AV4 12 103 38 AV4 10 58 39 AV3 6 104 36 AV2 13 58 39 AV4 14 104 36 AV3 9 58 39 AV6 13 104 36 AV5 10 62 40 AV2 23 104 38 AV3 10 62 40 AV3 31 104 38 AV4 16 62 40 AV4 24 104 38 AV5 12 62 40 AV5 12 104 42 AV3 17 65 28 AV5 9 104 42 AV4 13 66 43 AV2 12 105 36 AV2 9 66 43 AV3 11 105 36 AV5 11 73 58 AV6 13 105 40 AV2 8 74 38 AV2 8 105 40 AV4 15 75 39 AV5 16 105 40 AV5 16 75 39 AV6 8 105 41 AV3 10 76 38 AV3 10 106 32 AV3 11 76 38 AV4 13 106 36 AV5 8 76 38 AV6 8 106 36 AV6 10 76 50 AV3 12 106 40 AV3 14 76 50 AV5 28 106 40 AV4 19 78 40 AV2 17 106 40 AV5 16 78 40 AV3 16 107 36 AV3 9 79 36 AV4 14 107 38 AV1 9 80 37 AV4 9 107 38 AV3 16 81 56 AV6 12 107 38 AV4 15 82 28 AV5 11 107 38 AV5 43 82 40 AV3 19 107 39 AV3 11 82 40 AV4 27 108 33 AV3 12 82 40 AV5 15 108 38 AV4 14 82 55 AV5 12 109 36 AV3 11 84 40 AV2 12 110 32 AV3 11 84 40 AV5 7 110 33 AV3 19 86 38 AV4 15 110 33 AV5 10 86 40 AV4 11 110 33 AV6 7 87 40 AV4 15 111 32 AV1 10 1

AV# - Location of AVB intersection with the tube (there are up to 6)

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report Vogtle 1R14: SG4 AVB Wear Indications (continued)

Col Row Location1 1R14 Col Row Location1 1R14 87 40 AV5 18 111 32 AV3 12 88 40 AV3 13 111 32 AV4 7 88 40 AV4 19 111 33 AV3 15 88 40 AV5 15 111 33 AV4 17 88 40 AV6 14 111 33 AV6 16 89 53 AV4 12 113 30 AV5 10 90 40 AV3 8 114 30 AV5 26 90 40 AV4 13 90 40 AV5 9 1

AV# - Location of AVB intersection with the tube (there are up to 6)

Two tubes were plugged due to AVB wear: SG1 R57 C44 and SG4 R38 C107 During 1R14, tube end inspections were performed. No indications were seen in SG1 or SG4. Indications found in SG 2 and SG3 are found in the table below.

Vogtle 1R14 Tube End Tack Zone PWSCC Indications Row Col Volts Deg Ind Per Locn Length CA SGID 1 15 2.89 29 SAI 100% TEH 0.19 2 1 24 1.38 22 SAI 67% TEH 0.21 2 1 27 2.35 26 SAI 85% TEH 0.16 2 16 116 4.55 33 MAI 100% TEH 0.16 2 22 97 4.51 33 SAI 98% TEH 0.13 2 1 76 0.49 60 SCI 81% TEH 41° 2 7 71 0.98 40 SCI 97% TEH 44° 2 14 69 1.74 47 MCI 97% TEH 71° 2 45 76 0.65 51 SCI 90% TEH 53° 2 50 40 1.18 77 MCI 100% TEH 60° 2 55 60 1.31 78 SCI 99% TEH 64° 2 1 8 4.31 24 MAI 100% TEH 0.23 3 1 12 4.69 25 SAI 98% TEH 0.10 3 1 20 6.7 34 SAI 98% TEH 0.12 3 1 21 2.29 19 SAI 100% TEH 0.10 3 1 22 1.11 24 SAI 100% TEH 0.11 3 1 53 2.26 20 MAI 100% TEH 0.08 3 1 61 2.4 37 SAI 100% TEH 0.17 3 1 65 2.4 29 SAI 100% TEH 0.08 3 1 69 6.35 37 SAI 100% TEH 0.15 3 1 73 2.92 32 SAI 100% TEH 0.12 3 1 75 4.9 34 SAI 100% TEH 0.12 3 1 76 1.26 34 SAI 100% TEH 0.08 3 1 79 5.27 34 SAI 100% TEH 0.12 3 1 84 4.35 21 MAI 100% TEH 0.14 3 1 100 2.11 24 SAI 99% TEH 0.18 3 1 102 3.34 33 SAI 100% TEH 0.14 3 E-8

Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report A single SG3 tube (R42C52) that exhibited an apparent 159° geometric discontinuity in the tube end region was preventively plugged. The initial response indicated OD origin, but upon re-test with magnetically biased +Point probe, the apparent amplitude decreased more than a factor of 2 accompanied by a phase angle shift of 20°. Although the Lead Analysts Review concluded that the signal most likely represented a geometric discontinuity, resulting in designation of the signal as a trackable anomaly (TRA), the tube was preventively plugged because of its location and circumferential character. See Table below for the NDE data R42C52. 100% of the tube ends in SG3 and SG2 were inspected.

Vogtle 1R14 Tube End Tack Zone Geometric Discontinuity Row Col Volts Deg Ind Per Locn Length CA SGID 42 52 4.03 52 TRA - TEH 159° 3 42 52 1.69 32 TRA - TEH 3 Number of Tubes Plugged The following table presents a summary list of all SG tubes plugged in Vogtle 1R14 due to inspection results and/or management determination.

Vogtle 1R14: Tubes Plugged (14)

SG Row Column Flaw Type Description 1 6 110 SCI Circumferential ODSCC 1 8 112 SCI Circumferential ODSCC 1 10 114 SCI Circumferential ODSCC 1 11 118 SCI Circumferential ODSCC 1 13 96 SCI Circumferential ODSCC 1 57 44 AVB wear 40% wear 2 34 104 SCI Circumferential ODSCC 3 6 119 SCI Circumferential ODSCC 3 13 107 SCI Circumferential ODSCC 3 42 52 Administrative Circumferential Anomaly 4 11 62 SAI Axial ODSCC 4 12 98 SCI Circumferential ODSCC 4 22 51 MCI Circumferential ODSCC 4 38 107 AVB wear 43% wear The following table lists the additional 33 tubes plugged due to the requirements of the tube pull damage recovery effort discussed in the following section.

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report Vogtle 1R14: SG4 Tube Pull Recovery Tube Plugging (33)

Column 59 Column 60 Column 61 Column 62 Column 63 Column 64 Row 6 R6C59 R6C60 Row 7 R7C59 R7C60 R7C61 Row 8 R8C59 R8C60 R8C61 R8C62 R8C63 R8C64 Row 9 R9C60 R9C61 R9C62 R9C63 R9C64 Row 10 R10C60 R10C61 R10C62 R10C63 R10C64 Row 11 R11C60 R11C61 R11C63 R11C64 Row 12 R12C60 R12C61 R12C62 R12C63 R12C64 Row 13 R13C61 R13C62 R13C63 Total plugging in the SGs after 1R14 is as follows:

SG1 - 15 tubes for a total of 0.27% tubes plugged SG2 - 15 tubes for a total of 0.27% tubes plugged SG3 - 28 tubes for a total of 0.50% tubes plugged SG4 - 63 tubes for a total of 1.12% tubes plugged Tube Pull To characterize the morphology of the OD degradation modes observed at the top of the tubesheet during 1R13and 1R14, i.e., axial and circumferential ODSCC, 2 tubes in SG4 exhibiting eddy current signals similar to those observed were selected as tube pull candidates. R11C62 presented axial ODSCC just below the top of the tubesheet. R12 C98 presented the largest amplitude of the circumferential OD indications, similar to 17 tubes plugged for this mechanism in 1R13.

During the tube pull operation, R11C62 was not completely severed, which damaged surrounding tubes. ECT was performed to determine the damage, along with secondary side visual inspection. The tube pull recovery effort required the plugging of 33 tubes, listed in the table above. The specimens were successfully removed but have not been analyzed.

Condition Monitoring Conclusions No indications, circumferential or axial, were found to exceed the in situ testing requirements or the tube integrity structural and leakage performance criteria condition monitoring requirements.

The axial and circumferential indications reported above the tube end weld zone satisfied the acceptance criteria imposed by the license amendment for Vogtle.

All of the circumferential indications reported were less than the 94° crack angle limit imposed for possible circumferential cracks in the lowest 1inch of the tube.

None of the axial indications reported interacted with the circumferential indications. One tube was plugged for a circumferentially-oriented anomaly that exceeded 150° arclength as a conservative preventive measure.

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Enclosure Vogtle Electric Generating Plant - Unit 1 1R14 Steam Generator Tube Inspection Report The number of indications including location, size, orientation, whether initiated on primary or secondary side for each service induced flaw within the thickness of the tubesheet, and the total of the circumferential components and any circumferential overlap below 17 inches from the top of the tubesheet were shown in the preceding section titled Service Induced Indication Descriptions.

There was no primary to secondary leakage during the 1R14 operating cycle.

Therefore, the calculated accident leakage, in accordance with the IARC Tech Spec change commitment, is zero.

Given the absence of operating leakage during Cycle 14, 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 identified no leakage.

Evaluation of the indications found in the 1R14 inspection confirms that the tube integrity structural and leakage performance criteria condition monitoring requirements as specified in NEI-97-06 Revision 2 are satisfied.

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