NL-07-1888, Twelfth Maintenance/Refueling Outage Steam Generator Tube Inspection Report
| ML072880102 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 10/12/2007 |
| From: | George B Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-07-1888 | |
| Download: ML072880102 (7) | |
Text
Southern Nuclear Operating Company, Inc.
Post Office Box 1295 Birmingham, Alabama 35201-1295 Tel 205.992.5000 October 12, 2007 SOUTHERN"\\.
COMPANY Energy to Serve Your World SM Docket No.:
50-425 NL-07-1888 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant Unit 2 Twelfth 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 twelfth maintenance/refueling outage (2R12). Also included in this report are the results of the chemical cleaning process applied to the Vogtle 2 steam generators during 2R12. Initial entry into Mode 4 occurred on April 18, 2007.
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely,
~~~
Manager, Nuclear Licensing BJG/DRG/phr
Enclosure:
2R12 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 Dr. W. D. Travers, Regional Administrator Mr. S. P. Lingam, NRR Project Manager - Vogtle Mr. G. J. McCoy, Senior Resident Inspector - Vogtle
Vogtle Electric Generating Plant Unit 2 Enclosure 2R12 Steam Generator Tube Inspection Report
Enclosure Vogtle Electric Generating Plant - Unit 2 2R12 Steam Generator Tube Inspection Report Introduction The Vogtle Electric Generating Plant Unit 2 twelfth maintenance/refueling outage (2R12) was conducted after a cumulative service equivalent to -16 EFPY (effective full power years); the Cycle 12 power generation was -1.4 EFPY.
Analyses based on conservative assumptions used in the Condition Monitoring and Operation 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 steam generator (SG) tubing eddy current inspections were performed by the Steam Generator Maintenance Services Group of the Westinghouse Nuclear Services Division. Secondary data analysis was performed by ANATEC under direct contract with Southern Nuclear.
2R12 Inspection Scope The base scope for 2R12 involved the scheduled inspections listed below in SGs 2 and 3.
o Bobbin examination of the full length of 100% of the tubes except for the U-bends of Rows 1 and 2, which were inspected from tube end to TSP#7 from both Hl and CL.
o 50% +PointlM RPC (mid-range) examination of small radius U-bends (Row 1 and Row 2).
o
~ 50% +PoinPM RPC (mid-range) examination top of tubesheet region (TIS) on Hl side +/- 3.00" plus areas of special interest arising from the 1R13 inspection (low Row, High Column area 216 tubes).
o +PointlM RPC (mid-range) tests of special interest, Hl and Cl, possible bobbin flaw locations (including U-bends).
o 100% +PointlM RPC examination of dents/dings ~5 Volts in U..,bends and hot leg straight length, not previously inspected during the current inspection period.
o 100% +PointlM RPC inspection of expanded tubesheet section bUlges (BlGs) and overexpansions (OXPs), TSH-17" to TSH+3" SG 2 (31 tubes) and SG 3 (25 tUbes).
o +PointlM RPC examination of areas of special interest related to possible loose parts.
o Visual inspection of tube plugs.
No scope expansions were required during the 2R12 steam generator tube inspection.
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Enclosure Vogtle Electric Generating Plant - Unit 2 2R12 Steam Generator Tube Inspection Report Damage Mechanisms Found and NDE Techniques Utilized The following damage mechanisms were discovered in Vogtle Unit 2 SG 2 and SG 3 during 2R12:
o Antivibration bar (AVB) wear was found in SG 2 (116 locations) and SG 3 (26 locations). AVB wear is identified during the bobbin inspection except for rows 1 and 2 which were inspected with +PoinPM RPC. Only one of the AVB wear indications was not seen in 2R10.
o One non-pluggable volumetric indication (VOL) was identified in SG 2 by special interest +PoinPM RPC testing of a possible bobbin Haw indication.
Service Induced Indication Descriptions The VOL indication was found during Vogtle 2R12 in SG 2 in the tube at location Row 1, Column 46. at approximately 11 inches above the top of the tubesheet (ITS) on the cold leg (CL) side. This VOL indication data is provided in the following table. The location was visually inspected and no indications of foreign objects were detected. No tubes were plugged as a result of this VOL indication.
The AVB wear data identified during Vogtle 2R12 is provided in the following tables. No tubes were plugged as a result of AVB wear.
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Enclosure Vogtle Electric Generating Plant - Unit 2 2R12 Steam Generator Tube Inspection Report Vogtle 2 Steam Generator 2 AVB Indications for 2R12 Row Column Location
% Depth Row Column Location
% Depth 29 10 AV5 10 58 70 AV2 9
34 12 AV3 7
51 71 AV6 11 36 14 AV4 7
44 72 AV5 15 38 15 AV2 11 51 72 AV2 9
42 19 AV3 14 51 72 AV3 11 42 19 AV4 14 51 72 AV4 9
42 19 AV5 13 51 72 AV5 11 43 20 AV1 9
57 72 AV1 14 43 20 AV2 14 40 73 AV5 15 50 29 AV6 16 40 73 AV6 13 49 32 AV4 13 43 73 AV4 24 52 35 AV6 14 52 73 AV2 9
54 38 AV1 12 52 73 AV3 21 54 38 AV4 10 52 73 AV4 39 38 39 AV3 13 52 73 AV5 29 38 39 AV4 13 52 73 AV6 31 38 39 AV5 19 38 74 AV2 14 39 43 AV2 17 38 74 AV3 17 39 43 AV3 19 38 74 AV4 12 39 43 AV4 15 38 74 AV5 10 39 43 AV5 11 38 74 AV6 9
39 43 AV6 10 42 74 AV2 29 39 44 AV3 10 42 74 AV3 24 39 44 AV5 11 42 74 AV4 11 39 44 AV6 9
42 74 AV5 10 40 48 AV4 19 42 74 AV6 11 40 48 AV5 11 49 74 AV3 21 57 49 AV6 13 51 74 AV3 16 42 50 AV2 13 51 74 AV4 12 42 50 AV3 10 51 74 AV5 9
42 50 AV4 9
51 74 AV6 9
40 54 AV3 12 57 79 AV3 10 59 56 AV4 14 57 79 AV4 10 40 58 AV2 19 38 81 AV2 12 40 58 AV3 30 38 81 AV5 14 40 58 AV4 15 38 81 AV6 10 40 58 AV5 34 56 82 AV5 10 40 58 AV6 12 55 84 AV1 7
40 63 AV3 11 55 84 AV4 11 43 64 AV1 11 54 86 AV4 11 E-3
Enclosure Vogtle Electric Generating Plant - Unit 2 2R12 Steam Generator Tube Inspection Report Vogtle 2 Steam Generator 2 AVa Indications for 2R12 (continued)
Row Column Location % Depth Row Column Location % Depth I I
87 51 AV2 17 AV6 10 53 90 51 87 AV3 19 91 AV2 49 22 51 87 AV4 21 49 11 91 AV3 51 87 AV5 29 50 91 AV4 12 39 88 AV4 14 51 91 AV3 10 42 88 AV2 11 91 AV4 11 51 53 88 AV4 11 51 91 AV5 13 53 88 AV5 16 51 91 AV6 13 50 89 AV3 11 52 91 AV4 13 50 89 AV4 12 38 100 AV3 14 50 89 AV5 11 36 106 AV3 10 50 89 AV6 36 AV4 11 106 10 51 89 AV4 17 36 106 AV5 12 51 89 AV5 26 36 106 AV6 9
51 89 AV6 39 107 17 AV2 9
51 90 AV4 14 AV1 28 115 13 51 90 AV5 14 28 115 AV6 18 53 90 AV4 10 12 121 AV6 10 Vogtle 2 Steam Generator 3 AVa Indications for 2R12 Row Column Location % Depth Row Column Location % Depth 12 32 AV2 11 AV1 58 49 13 I
32 12 AV5 18 49 AV5 15 58 34 AV5 13 18 58 AV6 14 49 41 19 AV4 13 42 AV4 8
53 44 23 AV3 10 11 39 72 AV2 50 29 AV4 10 72 39 AV3 14 48 37 AV3 39 72 AV4 12 14 51 38 AV5 10 41 77 AV4 23 54 38 77 18 AV5 17 41 AV5 57 48 AV4 11 57 78 AV2 10 57 48 AV5 AV2 21 14 56 82 57 48 AV6 16 56 82 AV3 30 57 49 AV4 11 21 82 AV4 56 E-4
Enclosure Vogtle Electric Generating Plant - Unit 2 2R12 Steam Generator Tube Inspection Report Number of Tubes Plugged No tubes were plugged during 2R12.
Total plugging in the Vogtle 2 SGs after 2R12 is as follows:
SG 1 - 5 tubes for a total of.09% tubes plugged SG 2 -12 tubes for a total of.21% tubes plugged SG 3 - 4 tubes for a total of.07% tubes plugged SG 4 - 21 tubes for a total of.37% tubes plugged Chemical Cleaning The chemical cleaning process applied to the Vogtle 2 SGs during 2R12 was recognized as part of the planned maintenance activities in the 2R12 Steam Generator Degradation Assessment. The compositions of the iron removal solutions were optimized based on the anticipated sludge and tube deposits inventories. As applied, this chemical cleaning operation incorporated elements of the EPRIISGOG process and employed several phases, wherein temperature adjustments were made to facilitate dissolution in specific regions of the bundle, such as TSP crevices and the ITS sludge region. Residual iron stage chemicals were removed by multiple rinse operations prior to the copper removal phase of the cleaning process. The process was completed after similar rinse steps following the copper removal step. All four SGs were subjected to chemical cleaning during 2R12.
Condition Monitoring Results No indications were found to exceed the condition monitoring limits specified in the Degradation Assessment.
The VOL indication in SG 2 did not exceed the plugging criteria or the Condition Monitoring limits as given in the 2R12 Degradation Assessment. Additionally, in situ pressure testing for leakage and for proof of pressure capability was not required since the VOL indication maximum depth does not support a potential for leakage and the bobbin amplitude (1.93 volts) did not approach the leak testing criteria from industry guidelines for wear morphologies.
None of the AVB wear indications in either SG 2 or SG 3 exceeded the plugging criteria. They did not exceed the Condition Monitoring limits as given in the 2R12 Degradation Assessment. The growth rates are essentially negligible.
Evaluation of the indications found during the 2R12 inspection indicate that the condition monitoring requirements for structural and leakage integrity as specified in NEI-97-06 Revision 2 are satisfied. No SG tube samples were pulled for laboratory examination during 2R12.
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