NL-12-0659, Fifteenth Maintenance/Refueling Outage Steam Generator Tube Inspection Report
| ML12093A048 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 03/30/2012 |
| From: | Ajluni M Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-12-0659 | |
| Download: ML12093A048 (10) | |
Text
Mark J. Ajluni. P.E. Southern Nuclear Nuclea r Lice nsing Director Operating Company. Inc.
40 Invern ess Center Parkway Post Office Box 1295 Birm ingham, Alabama 3520 1 Tel 205.992.7673 March 30 , 2012 Fax 205.992.7885 Docket Nos.: 50-425 SOUTHERN . \
COMPANY U. S. Nuclear Regulatory Commission NL-12-0659 ATTN : Document Control Desk Washington , D. C. 20555-0001 Vogtle Electric Generating Plant - Unit 2 Fifteenth 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 2 fifteenth maintenance/refueling outage (2R 15). Entry into Mode 4 occurred on October 9, 2011 .
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 MJAlRMJ/lac Enclosure : 2R15 Steam Generator Tube Inspection Report cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski , Chairman , President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. T. E. Tynan , Vice President - Vogtle Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President _. Fleet Operations RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. P. G. Boyle, NRR Senior Project Manager - Vogtle Mr. L. M. Cain, Senior Resident Inspector - Vogtle
Vogtle Electric Generating Plant - Unit 2 Fifteenth MaintenancelRefueling Outage Steam Generator Tube Inspection Report Enclosure 2R15 Steam Generator Tube Inspection Report
Enclosure Vogtle Electric Generating Plant - Unit 2 2R15 Steam Generator Tube Inspection Report Introduction The 2R15 outage was conducted after cumulative service equivalent to - 20.0 EFPY (effective full power years); the Cycle 15 power generation was -1.4 EFPY. Analyses based on conservative assumptions used in the Condition Monitoring (CM) and Operational Assessments demonstrated that there were no tubes that exceeded the Regulatory Guide 1.121 or the NEI 97-06 Revision 3 criteria for tube integrity during Cycle 15. The eddy current inspections were performed by the Steam Generator (SG) 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). One tube (R53 C43) in SG 4 was plugged due to a 44% through wall wear indication that exceeded the Technical Specifications (TS) plugging criteria. Criteria for in-situ testing were not met for the tube. The H*
Alternate Repair Criteria was approved for implementation during 2R15. Therefore, tube end
+Point inspections below top of tubesheet (TIS) -15.2" were omitted, and the hotleg (HL) TTS inspection samples ranged from TIS +3" to TIS -15.2".
2R15 Scope The scope for 2R15 involved the scheduled inspections listed below. The inspection program, required by Revision 7 of the EPRI PWR SG Examination Guidelines, addressed the known degradation mechanisms observed in Vogtle Unit 2 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 examination of Row 1 and Row 2 U-bends from the top TSP on the HL to the top TSP on the CL in SGs 1 & 4.
- +Point examination of Special Interest locations of possible bobbin flaws in the HL and CL of SGs 1 & 4 (including U-bends).
- 50% +Point examination at HL tubes in SGs 1 & 4 from the top of tubesheet (TIS) to the licensed Temporary Alternate Repair Criteria (TARC) depth for H* (tubesheet region on HL side (TSH) +3/-15.2 inches). This inspection captured the TTS and BLG / OXP populations, as defined below, and the required periodic sample that carne with regulatory approval of TARC.
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.
- +Point examination of 50% of dents (DNT) and dings (DNG) ~2 volts in HL straight lengths and U-bends of SGs 1 & 4. This sample was taken from the total number of dents and dings identified during previous inspections and any additional identified by the bobbin program.
- Visual inspection of tube plugs in SGs 1 & 4.
- Slippage monitoring in accordance with regulatory requirements for the licensing of H* in SGs 1 & 4.
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Enclosure Vogtle Electric Generating Plant - Unit 2 2R15 Steam Generator Tube Inspection Report Damaqe Mechanisms Found and NDE Techniques Utilized All of the damage mechanisms found during 2R15 inspections were identified in previous inspections and in the 2R15 SG Degradation Assessment.
- Mechanical Wear due to a foreign object was found in SG 1. +Point and bobbin techniques were used to evaluate the wear.
- Mechanical Wear at anti-vibration bars (AVBs) was found in SGs 1 & 4. Bobbin technique was used to evaluate the wear.
Service Induced Indication Descriptions Foreign Object Wear Two sets of adjacent small amplitude potential loose part (PLP) indications at the top of the HL tubesheet (TSH) on R28 C91 and R29 C91 along with R48 C86 and R49 C86 in SG 1 were observed during Vogtle 2R15. The PLP locations in tube Column 91 were reported as No Detectible Degradation (NOD) at the 2R13 inspection. These tubes were boxed in with +Point and visual confirmation was also performed during 2R15 with no further indications of a foreign object. The PLP indications in Column 86 were reported in 2R13 and boxed in with +Point at that time. No wear was reported on any of the tubes in the boxed in area and visual inspection of Column 85-86 revealed no foreign object present. A +Point box in inspection was also performed during 2R15 of tubes surrounding the PLP indications in SG 1 tubes R48 C86 and R49 C86. As a result of the +Point box in of these PLPs, a foreign object wear call was made on SG 1 R47 C85 at 8% through-wall (%TW). A subsequent +Point box in of SG 1 R47 C85 showed no further evidence of foreign object interaction in adjacent tubes.
Visual confirmation of the PLP indications in SG 1 R48 C86 and R49 C86 and the wear indication at R47 C85 has been performed during the 2R15 SG secondary side inspections. The region, including in-between tube Columns 84-85, 85-86 and 86-87, was visually inspected prior to TIS sludge lance cleaning. Although the wear scar at R47 C85 was visible in some instances, there were no foreign objects present in the inspected region. As this location is approaching the tube bundle periphery, there was no significant buildup of tubesheet deposits that would mask the presence of a foreign object. Therefore, based on the available eddy current and visual inspection data, it has been concluded that the wear indication in SG 1 R47 C85 is most likely the result of a transient foreign object which is no longer present at this or adjacent locations.
+Point testing has been performed of all tubes adjacent to those listed in the table below in conjunction with a secondary side visual inspection of the locations to confirm there is no degradation and/or foreign objects associated with the corresponding PLP and tube wear calls.
Based on the inspection data, these indications did not exceed the CM limits and did not require in-situ proof of pressure testing to demonstrate tube integrity. Table 1 presents the foreign object wear and PLP indications identified in SG 1.
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Enclosure Vogtle Electric Generating Plant - Unit 2 2R15 Steam Generator Tube Inspection Report Tabl e 1 Vogt Ie 1 PLP/Forelgn Ob"IJect Wear f or2R15 SG Row Column Degree Volts Indication %TWD Location 1 29 91 80 0.14 PLP - TSH 1 28 91 80 0.15 PLP - TSH 1 47 85 96 0.09 peT 8 TSH 1 49 86 33 0.27 PLP - TSH 1 49 86 78 0.19 PLP - TSH 1 48 86 49 0.42 PLP - TSH 1 48 86 82 0.37 PLP - TSH 1 48 86 81 0.24 PLP - TSH Where:
%TWD = Percent Through-wall Depth, PLP = Possible Loose Part, TSH :: Tubesheet region on HL side peT = Percent (Foreign Object Wear)
Anti-Vibration Bar (A VB) Wear AVB wear continued to be identified in Vogtle 2R15 in SG 1 and SG 4. AVB wear identified in SG 1 is presented in Table 2. AVB wear identified in SG 4 is presented in Table 3.
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Enclosure Vogtle Electric Generating Plant - Unit 2 2R15 Steam Generator Tube Inspection Report Ta bl e 2 Vogt e 2 R 15 SG 1AV 8 Wear Indications 1
Row Col Location 2R15 % Row Column Location1 2R15%
30 10 AV2 10 37 33 AV3 10 30 10 AV6 12 53 33 AV4 18 34 13 AV2 13 53 34 AV3 14 34 13 AV4 14 53 34 AV4 12 35 14 AV4 13 37 35 AV3 9 41 20 AVl 11 47 36 AVl 11 41 20 AV2 21 47 36 AV3 12 41 20 AV3 13 49 36 AV2 17 41 20 AV4 17 49 36 AV5 22 41 20 AV5 16 37 39 AV4 8 41 20 AV6 9 55 39 AV2 10 42 20 AV2 22 55 39 AV3 12 43 21 AV3 12 46 43 AV2 11 43 21 AV4 12 54 50 AV2 14 44 22 AV4 17 54 50 AV3 11 44 22 AV6 13 54 50 AV4 11 41 23 AV5 16 58 53 AVl 15 41 23 AV6 12 59 68 AVl 13 44 23 AV2 14 44 72 AV6 10 44 23 AV3 19 58 72 AVl 14 44 23 AV4 17 58 73 AVl 12 44 23 AV5 27 35 74 AV4 13 46 24 AV4 15 55 78 AVl 11 34 25 AVl 9 55 81 AV2 10 46 26 AV4 18 53 89 AV5 13 41 27 AV5 13 50 92 AV2 14 44 27 AV2 12 50 93 AV3 15 44 27 AV3 15 44 94 AV5 15 44 27 AV5 11 48 96 AV2 12 47 27 AV2 24 41 99 AV2 15 48 27 AV2 11 41 99 AV5 14 48 27 AV3 17 43 100 AV2 13 48 28 AV2 17 43 100 AV3 18 49 29 AV6 10 43 100 AV4 21 50 29 AV5 16 43 100 AV5 11 46 32 AV3 16 29 105 AV2 11 46 32 AV4 19 32 106 AV5 13 46 32 AV5 14 29 112 AV2 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 2 2R15 Steam Generator Tube Inspection Report Ta bl e 3 Vog tl e 2R15 SG4 AVB Wid" ear n Icatlons Row Col Location 2R15% Row Col Location 1 2R15 %
30 9 AV5 19 55 41 AV5 14 29 14 AV6 8 44 42 AV3 11 36 14 AV2 14 44 42 AV4 17 43 21 AV5 12 44 42 AV5 23 43 21 AV6 12 44 42 AV6 14 43 22 AV4 14 30 9 AV5 19 45 22 AV2 10 51 54 AV3 12 45 22 AV3 12 51 54 AV4 24 45 23 AV2 8 51 54 AV5 12 45 23 AV3 10 50 55 AV3 8 45 23 AV5 9 51 55 AV2 12 39 26 AV3 9 51 55 AV3 20 46 26 AV4 12 42 56 AV6 10 46 26 AV6 13 48 57 AV3 10 44 29 AV3 17 48 57 AV4 10 44 29 AV4 17 48 57 AV5 16 46 31 AV2 11 58 57 AV3 9 46 31 AV3 23 58 57 AV4 9 46 31 AV4 14 43 58 AV4 12 46 31 AV5 16 43 58 AV5 10 48 31 AV3 9 45 58 AV3 23 48 31 AV4 13 45 58 AV4 11 51 31 AV4 16 45 58 AV5 18 45 32 AV3 25 48 58 AV4 10 52 33 AV2 16 44 59 AV1 12 52 33 AV3 18 44 59 AV3 14 52 33 AV4 18 44 59 AV4 12 52 33 AV5 38 51 60 AV3 14 52 33 AV6 16 59 63 AV6 9 53 34 AV2 13 39 64 AV1 14 53 34 AV6 12 39 64 AV2 22 43 35 AV2 14 39 64 AV3 29 51 35 AV4 17 39 64 AV4 14 54 35 AV4 13 39 64 AV5 11 54 35 AV5 22 39 64 AV6 20 54 35 AV6 12 43 65 AV4 16 15 36 AV6 8 45 66 AV2 16 43 36 AV2 16 45 66 AV3 13 47 36 AV4 14 45 66 AV5 17 53 36 AV5 14 52 66 AV1 9 54 37 AV1 13 52 66 AV2 18 54 37 AV6 12 52 66 AV3 11 38 39 AV4 10 59 66 AV6 11 51 39 AV2 13 43 68 AV3 18 51 39 AV3 13 43 68 AV4 22 51 39 AV4 18 43 68 AV5 21 47 41 AV2 14 43 69 AV5 17 47 41 AV3 12 50 70 AV3 16 1 AV# - Location of AVB intersection with the tube (there are up to 6)
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Enclosure Vogtle Electric Generating Plant - Unit 2 2R15 Steam Generator Tube Inspection Report Table 3: Vogtle 2R15 SG4 AVe Wear Indications (continued) 1 Row Column Location 2R15% Row Col Location 2R15 %
43 71 AV4 11 49 53 AV3 10 52 71 AV1 11 49 53 AV4 8 52 71 AV2 21 50 53 AV3 8 52 71 AV3 25 44 54 AV1 12 57 71 AV6 13 44 54 AV2 16 52 72 AV2 27 44 54 AV5 25 52 72 AV3 14 43 76 AV5 18 57 73 AV2 15 51 76 AV4 17 37 74 AV3 12 51 76 AV5 16 53 73 AV4 14 57 76 AV5 14 58 75 AV2 11 52 78 AV4 13 51 54 AV3 12 57 78 AV2 13 45 42 AV4 21 57 78 AV4 11 56 42 AV6 12 57 78 AV6 13 51 43 AV3 11 27 79 AV5 8 51 43 AV4 14 37 79 AV1 10 51 43 AV5 15 38 79 AV1 8 53 43 AV1 11 40 79 AV1 10 53 43 AV2 14 48 79 AV2 9 53 43 AV3 44 48 79 AV3 7 53 43 AV4 25 53 80 AV5 13 53 43 AV5 25 34 81 AV1 9 53 43 AV6 11 35 81 AV1 9 44 44 AV3 17 37 81 AV1 11 53 44 AV3 15 38 81 AV1 10 52 45 AV2 11 48 81 AV1 8 52 45 AV3 17 56 82 AV2 14 52 45 AV4 18 49 83 AV3 16 52 45 AV5 13 54 83 AV5 11 56 45 AV4 14 55 83 AV5 13 56 45 AV5 12 43 85 AV4 13 15 46 AV1 7 44 85 AV3 9 43 47 AV2 12 52 85 AV1 10 56 47 AV3 20 42 87 AV3 9 58 47 AV5 13 46 88 AV3 10 58 47 AV6 13 53 89 AV6 11 57 48 AV2 15 51 92 AV1 13 57 48 AV3 20 49 93 AV4 20 57 48 AV4 14 49 93 AV5 24 57 48 AV5 35 49 96 AV2 13 57 48 AV6 13 48 97 AV2 11 42 51 AV6 10 48 97 AV3 13 43 51 AV6 11 40 106 AV1 11 46 51 AV6 12 40 106 AV3 10 43 53 AV3 8 32 109 AV6 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 2 2R15 Steam Generator Tube Inspection Report Mechanical Wear and Wall Loss from Secondary Side Cleaning There are two previously unidentified indications in SG 1 at R1 C42 and R1 C45 sized at 8%
TW and 12% TW, respectively. Bobbin testing of both tubes was performed in 2R13. The indication on R1 C45 had been resolved as a No Degradation Found (NDF) result from +Point examination and R1 C42 was resolved as 1\100. An engineering review by SNC, Westinghouse and NDE Technologies of the available 2R13 data show an essentially identical bobbin signal response for R1 C42 and +Point response for R1 C45 in comparison to the 2R15 NDE data.
Therefore, no apparent growth of these indications has occurred between the 2R13 and 2R15 inspections. Based on the inspection data, these indications did not exceed the CM limits and did not require in-situ proof of pressure testing to demonstrate tube integrity.
Slippage Monitoring Bobbin data from SG 1 and SG 4 was screened for tubesheet indications of great than 50 volts with a phase angle between 25 and 50 degrees, and no tube severance indications were found.
There was no leakage present during Cycle 15. Therefore, the performance criteria for Cycle 15 with respect to TARC have been satisfied.
Number of Tubes Plugged Table 4 presents a summary list of the SG 4 tube plugged in 2R15 and the related degradation mechanism.
Ta ble 4 2R15 PI uggedTube SG Row Column Indication Degradation Mechanism 4 53 43 peT AVB Wear >40% TW Total plugging in the SGs after 2R15 is as follows.
SG 1- 6 tubes for a total of .11 % tubes plugged SG 2- 14 tubes for a total of .25% tubes plugged SG 3- 4 tubes for a total of .07% tubes plugged SG 4- 22 tubes for a total of .39% tubes plugged Condition Monitoring Conclusions No indications were found to exceed the CM limits specified in the Degradation Assessment.
This included +Point testing of the following: I-code indications; the tubesheet H* region; the top of the tubesheet; the BLG/OXP population; DNG/DNT locations; and small radius U-bends. No tubes exhibited degradation that required in-situ pressure testing to demonstrate structural or leakage integrity.
None of the AVB wear indications in either SG 1 or SG 4 exceed the CM limits as given in the 2R15 Degradation Assessment. One tube in SG 4 was plugged due to AVB wear indications that exceeded the Technical Specifications plugging criteria.
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Enclosure Vogtle Electric Generating Plant - Unit 2 2R15 Steam Generator Tube Inspection Report No secondary side tube damage attributable to loose parts/foreign objects in excess of the Vogtle 2 CM limits was identified from the foreign object search and retrieval (FOSAR) and visual inspections.
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 SGs 1 & 4, which produced no exceptions to expected conditions.
Evaluation of the indications found in the 2R15 inspections confirms that the tube integrity structural and leakage performance criteria eM requirements as speci"fied in NEI-97-06 Revision 3 are satisfied. The evaluation for SGs 1 & 4 in 2R15 is applicable through Cycle 17. The evaluation of the indications, found in 2R14, remain valid for Cycle 16 for SGs 2 & 3.
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