NL-12-1790, Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspections

Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspections

ML12243A249
Person / Time
Site:	Vogtle
Issue date:	08/29/2012
From:	Ajluni M Southern Co, Southern Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
NL-12-1790
Download: ML12243A249 (9)

Text

Mark J. Ajluni. P.E. Southern Nuclear Nuclear Licensing Director Operaling Company. Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.7673 Fax 205.992.7885 August 29, 2012 SOUTHERN'\'

COMPANY Docket Nos. : 50-425 NL-12-1790 U. S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant - Unit 2 Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspections Ladies and Gentlemen:

By letter dated March 30, 2012 (Agencywide Documents Access and Management System (ADAMS), Accession Number ML12093A048), Southern Nuclear Operating Company (SNC) submitted information summarizing the results of the 2011 steam generator tube inspection performed at Vogtle Electric Generating Plant (VEGP), Unit 2, during refueling outage 15 (2R15). On August 1, 2012, the Nuclear Regulatory Commission (NRC) provided SNC with a Request for Additional Information (RAI) letter (ADAMS Accession No. ML12213A292) containing questions regarding the VEGP 2R15 Steam Generator Tube Inspection Report. The August 1,2012 letter requested responses to these questions within 30 days. contains the SNC responses to the NRC questions from the August 1, 2012 letter. Enclosure 2 contains the corrected Tables 2 & 3 from the VEGP 2R15 Maintenance / Refueling Outage Steam Generator Tube Inspection Report.

These tables list the antivibration bar (AVB) wear indications identified during 2R15.

This letter contains no NRC commitments. If you have any questions, please contact me at (205) 992-7673.

Respectfully submitted ,

M. J. Ajluni Nuclear Licensing Director MJAlRMJ/Iac

Regulatory Commission

1. Response to RAI Questions Revised Tables 2 & 3 from the VEGP 2R15 ....to." .....

Tube Inspection Report cc: Southern Nuclear Operating Company Mr. Kuczynski, Chairman, President &

Mr. D. Bost, Executive Vice President & Chief Nuclear Mr. 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. R Martin, NRR Senior Project Manager -

Mr. L. M. Cain, Senior Resident Inspector - Vogtle Mr. M.O. Miller, Senior Project Engineer, NRC II

Vogtle Generating Plant - Unit 2 Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspections Enclosure 1 Response to RAI Questions to NL-12-1790 Response to RAI Questions NRC Question 1:

Please discuss the scope and results of any secondary side inspections (e.g., upper bundle, steam drum) performed in the SGs during 2R15 (Fall 2011).

SNC Response:

Secondary side maintenance and inspection activities performed at the Vogtle Electric Generating Plant (VEGP), Unit 2, during refueling outage 15 (2R15) in Fall 2011 included top of tubesheet (TIS) sludge lancing, foreign object search and retrieval (FOSAR), and upper internal steam drum inspections of all four steam generators (SGs). FOSAR inspections included the following regions:

• Annulus and tubelane region including periphery tubes

• Possible loose parts (PLPs) from eddy current tube inspections Sludge lancing removed a total of 17.5 pounds of material from all four SGs. After FOSAR, 22 objects remained in the SGs. All the objects remaining in the SGs were classified as Category 3 and are not expected to cause significant tube wear over long term operation. This classification is taken from EPRI Report Number 1019039, "Steam Generator Management Program: Foreign Object Prioritization Strategy for Square Pitch Steam Generators," May 2009.

Upper Internals/Steam Drum inspections included secondary moisture separators, primary moisture separators, downcomer barrel and tangential nozzle assemblies, all deck plates, and the feedwater distribution rings. Wall thickness measurements of all four feedwater rings was taken using ultrasonic testing (UT). Additional visual inspections were performed within the feedwater rings and their J-nozzles, as well as visual inspection of the weld backing rings.

All components were found to have a uniform coating of tightly adhering magnetite. None of the weld backing rings observed during the VEGP 2R15 inspections revealed changes from the VEGP Unit 2 refueling outage 9 (2R9) inspections. Visual inspections within all four SG feedwater rings revealed early signs of feedwater ring base material loss on a limited number of feedwater ring to J-nozzle joints. UT thickness measurements of the feedwater rings also identified several areas of local thinning. An engineering evaluation concluded that, for all of the VEGP Unit 2 SGs, the identified conditions are not expected to adversely affect the thermal performance function and structural integrity of the feedwater rings or other upper steam drum components. Also, the identified conditions are not expected to develop loose fragments within the SGs which would subsequently impact the SG tubes.

E1-1 to i'JL-1 790 Response to RAI Questions I-I'II!Uilll:1!> confirm the Table 3 there at one duplicate entry (row 30, column 9), and the order is not discernible (neither rows nor columns are in ascending order).

In SNC dated March 30, 201 Table 2 and anti-vibration wear indications identified in 1 and SG 4 during 2R15. Both were reviewed for accuracy and reformatted with tube column number in ascending order. Table 2 reported row 47, column 99 with two AVB percent wear indications instead of row 41, column 99 with two AVB percent wear indications. 3 contained two (row 30, column 9 and row 51, column 54). Table 3 also should have reported row 53, column with a single AVB wear indication instead of row column 73 with a single AVB percent wear indication. Table 2 and Table 3 been corrected and are given as Enclosure errors have documented in the SNC corrective action program.

NRC Question 3:

Please confirm that there was no evident in bobbin and +Point' data between 2R13 and 2R15 for the tubes in row 1, column 42 and row 1, column in SG 1.

Bobbin testing of 1 row 1, column and 1 row 1, column 45 was performed in VEGP Unit 2 refueling outage 13 (2R13). Additional +Point examination was performed on SG 1 row 1, column 45. The indication on row 1, column was resolved as a No Detectable Degradation (NDD) indication code based on the bobbin testing. indication on row 1, column had resolved as a No Degradation Found (NDF) indication from +Point examination. An engineering review of the 3 data, in comparison the 2R15 non destructive data, showed an essentially identical bobbin response for row 1, column 42 and showed an essentially identical +Point response for row 1, column Therefore, no apparent growth of these indications occurred between the 3 and 2R15 inspections.

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VogUe Electric Generating Plant - Unit 2 Response to Request for Additional Information Regarding the 2011 Steam Generator Tube Inspections Enclosure 2 Revised Tables 2 & 3 from the VEGP 2R15 Steam Generator Tube Report

2 to NL-1 790 2 & 3 from the VEGP 2R15 Steam Generator Tube Inspection Report Anti-Vibration Bar {A VB) Wear AVB wear continued to be identified in Vogtle 5in 1 and AVB wear identified in SG 1 is presented in Table AVB wear identified in SG 4 is presented in Table Row Row Column location 2R15%

30 37 33 AV3 10 30 53 33 AV4 18 53 14 53 12 37 9 11 47 11 21 47 12 13 49 17 17 49 36 AV5 22 16 37 39 8 9 55 10 22 55 39 12 12 46 11 12 54 14 17 54 11 44 13 54 11 41 16 58 AV1 15 41 12 59 AV1 13 44 14 44 72 AV6 10 19 58 72 14 17 58 73 27 35 74 15 55 78 9 55 81 18 53 89 13 50 12 50 93 AV3 15 44 94 27 AV5 11 48 96 AV2 12 27 AV2 24 47 99 AV2 15 27 AV2 11 47 99 14 27 AV3 17 43 100 13 17 43 100 18 10 43 100 21 16 43 100 11 16 29 105 11 19 32 106 13 14 29 AV2 10 to NL-1 Revised Tables 2 & 3 from the 2R15 Generator Tube Inspection Report 5 SG4 AVa Wear Indications Row Col 2R15%

55 41 44 42 11 17 23 14 14 21 10 12 12 8

10 9

9 12 13 17 17 11 44 17 23 53 15 14 52 11 16 52 17 9 52 18 13 14 12 14 17 13 57 22 42 12 43 8 46 16 43 14 49 AV3 49 AV4 50 AV3 44 AV1 44 AV2 16 AV5 25 AV3 12 54 AV4 24 AV5 12 47 AV3 8 are up to 6)

E2-2

Enclosure 2 to I\IL-1 790 Revised Tables 2 & 3 from the 2R15 Steam Generator Tube Inspection Report Table 3: Vogtle 2R15 SG4 AVe Wear Indications (continued)

~

Row Column locationl n.

Col location 1 2R15 %

51 55 AV2 52 72 AV3 14 51 55 AV3 20 57 73 AV2 15 42 56 AV6 I 10 37 74 AV3 12 48 57 AV3 10 53 74 AV4 14 48 57 AV4 10 58 75 AV2 11 48 57 AV5 16 43 76 AV5 18 58 58 57 57 AV3 AV4 9 9

-+-- 51 51 76 H==AVS AV4 17 16 43 58 AV4 12 57 7 AV5 14 43 58 AV5 10 AV4 13

~

45 48 44 58 58 59 AV3 AV4 AV5 AV4 AV1 23 11 18 10 12 tt4 27 37 78 78 78 79 79 AV2 AV4 AV6 AV5 AV1 13 11 13 8

10

~p AV3 14 38 79 AV1 8 44 AV4 12 40 79 AV1 10 51 59 39 63 64 AV3 AV6 AV1 14 9

14 48 48 53 79 79 80 AV2 AV3 AV5 H

13 39 64 AV2 34 81 AV1 9 L 39 39 64 64 AV3 AV4 ~ 35 37 81 81 AV1 AV1 9

11 39 39

~

64 I AV5 AV6 11 20 38 48 81 81 AV1 AV1 ~ 10 8

43 65 AV4 16 56 82 AV2 14 16 45 45 45 66 66 66 AV2 AV3 AV5 16 17 3

49 54 55 H83 AV3 AV5 AV5 11 13

! 52 66 AV1 9 43 85 AV4 13 52 66 AV2 18 44 85 AV3 9 52 66 AV3 11 52 85 AV1 10 59 66 AV6 11 42 87 AV3 9 43 AV3 18 46 88 AV3 10 43 68 AV4 22 53 89 AV6 11 43 68 AV5 21 51 92 AV1 13 43 69 AV5 17 49 93 AV4 20

~D 50 AV3 16 I 49 93 I AV5 24 43 AV4 49 96 AV2 13 I 52 71 AV1 11 48 97 AV2 11 52 71 AV2 21 48 97 AV3 13 52 71 AV3 25 40 106 AV1 11 57 71 AV6 13 40 106 AV3 10 52 72 AV2 27 32 109 AV6 10 1 AV# - Location of AVB the Ibe are u p to 6